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Han, M. Zhu, Y. Li, and and L. Chen, Lower Cambrian vertebrates from south China. Cartwright P, H. Published online August Vergara-Silva, F.


Philos, p. Miller, R. Biology of Fertilization, Vol. Yoshida, M. Inaba, and M. Morisawa, Sperm chemotaxis during the process of fertilization in the ascidians Ciona savignyi and Ciona intestinalis. Dev Biol, Ward, G. J Cell Biol, Kamei, N. Genes Dev, Alberts, B. Evans, J. Florman, The state of the union: the cell biology of fertilization. Nat Cell Biol, Yuan, R. Primakoff, and D. Myles, A role for the disintegrin domain of cyritestin, a sperm surface protein belonging to the ADAM family, in mouse sperm-egg plasma membrane adhesion and fusion.

Hamilton, B. Whittaker, and S. Daniel, Influenza virus-mediated membrane fusion: determinants of hemagglutinin fusogenic activity and experimental approaches for assessing virus fusion. Viruses, Plotch, S. J Virol, Bagai, S. Capelson, M. Doucet, and M. Hetzer, Nuclear pore complexes: guardians of the nuclear genome. Wilson, G. Nucleic Acids Res, Murray, Restriction and modification systems. Annu Rev Genet, Jurka, J. Bao, and K. Kojima, Families of transposable elements, population structure and the origin of species.

Biol Direct, Doebley, J. Stec, and L. Hubbard, The evolution of apical dominance in maize. Wang, H. JPG, Active site as seen in the induced fit model of enzyme action. Logsdon, J. Doolittle, Origin of antifreeze protein genes: a cool tale in molecular evolution. Cui, L. Genome Res, Pennisi, E. Genome duplications: the stuff of evolution? Science, Ronshaugen, M. McGinnis, and W. McGinnis, Hox protein mutation and macroevolution of the insect body plan.

Lenski, R. Evolutionary Genetics: Concepts and Case Studies. Microbiology Today, 31 : p. Holmes, E. PLoS Biol, Iyer, L. Virus Res, Simonsen, L. Mol Biol Evol, Fostinis, Y. Biochem Cell Biol, Queitsch, C. Sangster, and S. Lindquist, Hsp90 as a capacitor of phenotypic variation.

Rutherford, S. Lindquist, Hsp90 as a capacitor for morphological evolution. Wagner, G. Chiu, and T. Hansen, Is Hsp90 a regulator of evolvability? J Exp Zool, Mackay, T. Stone, and J. Ayroles, The genetics of quantitative traits: challenges and prospects. Nat Rev Genet, Paran, I. Zamir, Quantitative traits in plants: beyond the QTL. Trends Genet, Plomin, R. Haworth, and O. Davis, Common disorders are quantitative traits. Dodd, D. Evolution, Huber, S. Grant P. Evolution, 48 : p. Grant, P.

Mallarino, R. Bell, M. Chouard, T. Hart, A. Curr Biol, Urban, M. Losos, J. Genetica, Linville, B. J Comp Physiol B, Petren, K. Mol Ecol, Tebbich, S. Sterelny, and I. Teschke, The tale of the finch: adaptive radiation and behavioural flexibility. Albrich, W.

Monnet, and S. Harbarth, Antibiotic selection pressure and resistance in Streptococcus pneumoniae and Streptococcus pyogenes.

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Emerg Infect Dis, Bennett, P. Br J Pharmacol, Chen, R. Quinones-Mateu, and L. Mansky, Drug resistance, virus fitness and HIV-1 mutagenesis. Curr Pharm Des, Yim, H. Hepatology, Nature, Mar Wright, Juno is the egg Izumo receptor and is essential for mammalian fertilisation. Nature, Apr Yang, Z. Pingoud, V. J Biol Chem, Singh, T. Pardasani, In silico analysis of evolutionary patterns in restriction endonucleases. In Silico Biol, Brown, K. Dalton, R. Banister, C. Craig and Nicholas C.

Epigenetics, Casadesus, J. Low, Epigenetic gene regulation in the bacterial world. Microbiol Mol Biol Rev, Chahwan, R. Wontakal, and S. Roa, The multidimensional nature of epigenetic information and its role in disease. Discov Med, Marcotte, E. List of figures Figure:1 Evolution chandelier. Figure:4 Neo-darwinian speciation.

Figure:5 Photograph and interpretive drawing of Middle Cambrian cnidarian jellyfish in lateral view. Figure:8 The molecules on the sperm surface, such as fertilin and cyritestin, may be involved in sperm—egg binding; Okabe and colleagues find that Izumo is essential for membrane fusion. Figure Nuclear pore complexes on the nuclear membranes of frog oocytes as seen from the cytoplasm. Figure Codon usage rose plots for two representatives of different species of Vibrio. Figure Direct repeats excising DNA.

Figure A simple regulatory region of DNA located upstream of the gene. Figure Eukaryotic promoters are extremely diverse and are difficult to characterize. Figure Most eukaryotic genes, coding regions exons are interrupted by non-coding regions introns. These duplications are most likely brought about by a heightened activity of transposons and small scale recombination events through repetitive elements.

Figure Crossover recombination at the chromosomal level between repeated DNA sequences at non-allelic positions can generate a deletion, a duplication, an inversion or an isodicentric chromosome. Figure Genome duplication: Hox clusters are indicative of whole-genome duplication events which happened across life forms.

Figure The circulating influenza-A viruses change by mutation, so antibodies become less effective at neutralizing the virus. Figure A taller breed of dog with one of the smallest breeds… Figure Some of the different breeds of dogs… Figure Inbreeding evasion experiment as observed by Diane Dodd in fruit flies. Figure The beak of the sharp-beaked finch, G. Figure Three spined stickle back. Figure The standard in vitro fertilization procedure.

Figure Liger. Figure Leopon. Figure Mule. Figure Hinny. Figure Zorse. Figure Zonkey. Figure Cama. Figure The names of the hybrids, formed between the different Equus species. Figure A picture of Mouse and Rat. Figure A picture of the different Camelids and their hybridization pattern. Figure Picture of a goat and sheep pair. Figure As visible both the restriction enzymes differ only slightly in their cleavage sites. Figure Macro-Species Branding among Restriction enzymes.

Figure An illustration of micro- and macro-evolution from the phenotypic perspective. Acknowledgements: I am very grateful to my Ph. D guide Prof. Michael Schleicher for his constant support and motivation; especially more so for his kindness. I am very fortunate to have had him as my doctor father; who according to me belongs to a rare breed of human individuals, who make decisions by not only listening to their brains but also to their hearts.

I am very thankful to my friend Dr. Arasada Rajesh. Pandey and other good hearts. I am also thankful to my earlier teachers and professors who have developed in me a thirst for life-sciences; namely Mr. Saravana Rajan, Mr. Radha Krishnan, Prof. Krishna Swamy, Prof. Dharmalingam, Prof. Shanmuga Sundaram. I also acknowledge the support I had received from all my friends around the world, many of whom, I unfortunately am not in constant touch.

Gnanashekar, Danush Jeyan and late Mr. Jawaharlal Paul. Most of all, I cherish the support and motivation I received from my family members; my mother I. Daisy Mary, my father V. M Joseph, my sister Sophia Jegan, my uncle Prof. Henry Louis, Aunt Jesintha and other dear ones. Pictures of the different primates, whose sequences have been used in this section.

This suggests that Neandertals could have interbreed with the Modern day humans. There are a total of three mismatches in both the proteins. These mismatches have most-likely played an important role in the branding of the Human species. They show multiple mismatches, and in certain cases at least a minimum of a single mismatch. The mismatches indicate the important role played by these branding factors, in the origination of new primate species. Following which new features will be added to it related to rules, no of players, types of coins etc so as to distinguish this game from any other previously known game…!

Up- ctly what is wrong with religion, be it starts songs have much more depth thaan Christian or Satanic. It breeds passive- any S. D, song, all S. Well just thought I What makes you think that Social D. I mean: look- society offers you a choice of conforming to the straight realm of society or to toe druggie real- m of society. I happen to be very close friends with a fe v. And I can also assure you that these are not the type who sympathise with punk because it's the in tiling, mon!

It becomes stupid to judge people by their hair legnth. I think the answer Is neither - think about that!! I agree that most churches and stuff are wrong in the way they conduct their actions but I don't agree that anyone should put down God. God never condones war!!

So all you dumbfucks you blame him for war shove it up your ass!!!! For proof that he does exist you only need to look at the Book of Revealations in the Bible. I'm not saying be an angel, 1 sin just as much as any of you, but 1 believe in God and try to love everyone!! Tracy Slater, Wa. PS: A very sad fact is that L.

Change J tiie word order, anything. In you last issue I read the interview with some third rate band named. The Condemned or Moral Decay, and it just doubled my discontent with people who bite off more tlan they can chew in the socio-political philosophy department. He Slid everything 1 would have and saved me the trouble of trying to get it all in another letter!. But what they fail to realize is that they are over generalizing and making anybody who wears a mohawk, leather, studs, spiked wrist bands etc sound like a total asshole or a jock.

You people have been fooled by the press just like the American public has been fooled about punk rock! Thanks - Tracy Slater, Wa. Which I think was accomplished. Maybe you can learn something about yourself from this experience. Sincerely, Michele F. Dear Flipside: Just a note to let you know how truely sorry I am about the letter you reciev- ed from our singer Joni. By the way, your reply was perfect!!

Biss - bass player - Savage Circle Dear Flipside: I just want to be among those who tell you you are geniuses for doing an all comic issue.! Really great! Really funny! TOP 6 1. Hardcore is about change through anger and power not about pounding the fuck out of each other like lemmings marching to the sea. I know by far punks are headed in the? Anarchy is not about chaos, that's what we liave now. What is your source of frustration. Frustration: Who is the real enemy?

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By next time we should have this all worked out. Stuart, Fresno, Ca. Lamont Drive, Cortland, N. B L. Point Trr. Miami, Fla. Yarmouth, Mass. Joseph St. Bissel, Chicago, Ill. Roscoe, Chicago, ni. Box , Santa Monica, Ca. Tioga St. SE, Grand Rapids, Mi. High St. Be more than a witness - publish a fanzine!!!!! Highland, Hollywood, Ca. An off-the-wall package well worth the bucks. And as an anthropological document of the early eighties, it captures a mood and tension felt nowhere else but in the headaches of struggling L.

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Featured are poets Bukowski. Hit list! Set your skin on fire Hit list!

From their mutant desire. Watch us burn!!!!! And on top of this good news is re still places to play locally well sometimes is better t at all and people are having parties again. And then there was 'foo's, as the story goes: Ritz man- Chuck moved his location erton calling it Mr. Consequently Chuck lost?

Boofoo's snide owners said no more p. However curent rumor has it that Fullerton's finest stepped HsBB. Speaking of Chuck and the Ritz, alot of O. Why should O. I call that r? Send your reply or death threats to our P. And we have a new x ollf J resident: a political pessimist named appropriately: Political Ron- from Michigan. Welcome to O. By the way, after much. Big movie plans 4. This is a! Boon trying his hand at being SPK. Tony Platon and Debt Z Tapes. They call this thrash, but if you of Nature. Records, is really a convienance because now you don 1!

Anyway, this tape has some really ycto Zgood stuff on it too bad most of these Jld What? I bands have broken up. In fact the only to mention some Uhreleased Skulls! Check it out today! Starts off with DOA. Just like the Woodstock album. Also great Z hits the nail right on the head! New Allia- Z are the Jonses wife their speeded ftp. All bands are recorded real [crude practical anarchy they say but come off quite powerful, sounding a lot like their western counterparts.

Sorry, no adress! But what direction will Jeff Dahl go? The b side has some decent, short punk tunes. They all suck, but YOU might like them, you scents do a couple songs off their first demo before Posh, before Frontier Battalion of Sa-. Legal Weapon. Great package too. LIF E. I was a bit disappoi- is Anally out also. I also hope familiar songs from their old demo.

Neat record. From bands. The same goes for the Crewd, some fairly good ideas here, good songs! Red Beret has cuts on both sides, real strong and heavy sounding a t parage Techno pop for all the niceTids. More music to shit your pants to. If you can believe that! Oh, they are jyou say. Oh well No way. A Jiice fun hateful ep. ZNow for something a little different, a. They even have their own alphabet and language.

An interesting band. Also on NLP is the Outsiders , who are. Pufrimr Pillnikk langements to the messages. The other ; you already know that! The group IS; Oh, the intros cool, damn good noise band. Now back to A1 for which is distributed over here by Green- ; some more tapes! Brilliant package, but for me ; only a few of the bands make it. Eastland St. Recomended highly. All kinds a shit here! Check it out. Ticonderoga Ln. Knoxville, Term. Willoughby, Ohio Yes we have books!

P from the unpredictable Red Cross. All 3 due out by Nov. H, or they can si. It has evolved its own kind of she would teve a et to say. She DID! It s a different world, always done alot of art. Took ait lessons Different kinds of corora derie and rivalry, as a kid. My grandmother is a painter. I There are small fangs and bigger gangs. It'S very exciting to me.

I want to. Helen: What about drugs? I stopped doing every- '10? RBp f? Tennis, swimming, running. Helen: Did affhtone approach you to do a recording? Raw 1 have friends who are doing my record and I trust them w- s Setter late than never How new wave! It start dressing like that I met you last summer in Ocean City, Maryland. Send records tapes anyUungt!! Folk Shows. For more info write: Media just doing it in a different way. Call I Phranc: It becomes a problem. Send records, tapes and telephone numbers for booking. N9, 1 Phranc: No. We inai was me stair 01 u.

Kindly quite a while Sorry and thanks, Chris and Kevin and Steve of she write songs about international g g politics. A Whittier ca gher attitude fairry well Keyboardist, guitarist needed - tapes from various noise makers for possible inclusion on Francine Lake this C affair. I like Minor Threat,. Hamilton Ave, State College, Pa. Raven X 23fc2nd St. Send 20? State topics -or- send 1 blank tape and 75? Three diff.

Noise, elect- you can rest assured that is not because he is too lazy or ronics rock. Constant Cause Arbor Ln. If you know of a cheap costing hall contact and giving him a chance to return it. Will pay from 25? Pet Puddv Will pay one dollar each. Contact: Disorderly , send to Flyers 7th St. Chicago, IU. Valentinos Haddonfieid Rd. Contact Mike or write Cedar Ave. N9, Andalusiu, Pa. We have a file with names, addresses and amounts of money sent to us but we need to know what you ordered. NO heavy druggies, burnouts, I hippies or bums, call before 4pm or write ; Chris Fresquez Comstock Av.

My name is Champ from New Orleans fanzine Christian Lecture, anyone interested in writing an article on the see scene where you live would be appreciated. When people heard the record that wasJ. We il your onlv opening now, 1 James: I mean some kind of unity behind. Mike heard our record on Rodney g and loved it. S ch I thought was great!! Have you been in his. Pete: What are your songs about? Sue: Is there any more beer? Sue: It varies but there is still a basic meaning. Rodney: Would you consider Phil Spector producing you? Mike heard our record on Rodney girls club!!

I ch I thought was great!! Annette: No way, I got kicked out!! Have you been in his w Vicky: Yeah, yeah our periods happen Debbie: No clooege for me! Al: Do they ever all coincide? H ah ha.. And Sal. Which face when you drum. Army practices under all those shirts!!! The head Sue: Siichi. I Pete: Would you play with the Gogos? Al: That would be too tacky Al: When ya gonna do an album? Vicky: In the fall we;ll put out an e.

I er me though. To be happy! Debbies a bum. Debbie: No clooege for me! Talk goes on to fleas, cockroaches, dogs cats and rabbits Vickie: Peanut butter!! Sue: Suchi. Pete: Would you play with the Gogos? Al: If you were on toe cover of Rolling Stone would you be in yer underwear? Sue: No. Vickie: Of course. Annette: Only if I had a bra on. Just kidding. Vicky: No, we gotta out do them. Sue: Anywazy James wants to know what our ultimate musical goals are. Ebooks

Vickey: Could it be any kind of goals? Personal goals? Hygenic goals? Rodney: Are you still teenagers? Vicky: I know, I take a lot of vitimins giggles hormone shots, steroids!!! Pooch: And you thought youu were short! Sue: I thought I was short! Hardy har har. Every block had one so for awhile I was real fascinated by like Fender guitars. A lot of the! There is a place for that but 5 there are other things to write about than I be bop stip stop plop bop. Some of those guys show gup at Blasters shows!

If you put anything an any sort of Oddish sense it becomes a fad and when you Took at the so called roc. S: But is the audience as sincere as you are about it? S: Too many cobblestone roads! S: And in America they sit on their butts waiting for an English band to come Dave: Exactly! S: That could be because it costs at least seven bucks to go see a show. John: We let me state right here that WE. Our hit record was just a crazy fluke.

No kidding, we shit in - our pants before every show. Hey we were in 5 Easy Rider magazine!! They put on a real intense show by playing ndn-stop. The night - HI ended in a haze as the beer was free! I laivry ami. Ultimately ij 8n product it can cope with - ultiif E r e are a. Won can you make for that? Jaz: K Eurcffi befoJ? Jaz: We have too rj ideas we started f twist everything. Al: What do you have to do? Will it be done as Killing Joke? Jaz: Sure, leave a mark. I maybe? Therefore why make a solitary effort except in personal development. Killing Joke. Jaz: Slaves. Slaves to themselves.

And that I con- of nature - survival of the fittest. What determines only tell. We all have strong imaginations along those jould come up with remarkable things. Most of all is using our will. Will is a key to? For example when a ratio- anything that is un realistic, they have automa- R cistance as far as m myself.

If I will e. If it is an indiv- Jd in 3 - 4 weeks ing can stop film from following that out. The endless potential - everything depends on the true will of the individual. I consider I tfi mwidual way to lo t the mercy of. Yet he pert! Which is fine because in one sense Killing Joke has always used fear of the elements, fear of that which is beyond and taken that orally more than any other unit. We first examine the host galaxy of SN if, an important member of the subclass of SNe Ia whose extreme brightnesses indicate a progenitor that exceeded the canonical Chandrasekhar-mass value presumed for normal SNe Ia , and show that the host galaxy of this SN is composed of very young stars and has extremely low metallicity, providing important constraints on progenitor scenarios for this SN.

We then utilize the full sample of SNfactory host galaxy masses measured from photometry and metallicities derived from optical spectroscopy to examine several global properties of SN Ia progenitors: i we show that SN Ia hosts show tight agreement with the normal galaxy mass-metallicity relation; ii comparing the observed distribution of SN Ia host galaxy masses to a theoretical model that couples galaxy physics to the SN Ia delay time distribution DTD , we show the power of the SN Ia host mass distribution in constraining the SN Ia DTD; and iii we show that the lack of ultra-low metallicities in the SNfactory SN Ia host sample gives provisional support for the theorized low-metallicity inhibition of.

Neill, James D. Christopher; Barlow, Tom A. Our data corroborate well-known features that have been seen in other SN Ia samples. Specifically, hosts with active star formation produce brighter and slower SNe Ia on average, and hosts with luminosity-weighted ages older than 1 Gyr produce on average more faint, fast, and fewer bright, slow SNe Ia than younger hosts.

A low host extinction subsample hints at a residual trend in peak luminosity with host age, after correcting for light-curve shape, giving the appearance that older hosts produce less-extincted SNe Ia on average. This has implications for cosmological fitting of SNe Ia , and suggests that host age could be useful as a parameter in the fitting.

Converting host mass to metallicity and computing 56 Ni mass from the supernova light curves, we find that our local sample is consistent with a model that predicts a shallow trend between stellar metallicity and the 56 Ni mass that powers the explosion, but we cannot rule out the absence of a trend. We measure a correlation between 56 Ni mass and host age in the local universe that is shallower and not as significant as that seen at higher redshifts. Progenitors of Type Ia supernovae SNe have been predicted to modify their ambient circumstellar CSM and interstellar environments through the action of their powerful winds.

While there is X-ray and optical evidence for circumstellar interaction in several remnants of Type Ia SNe , widespread evidence for such interaction in Type Ia SNe themselves has been lacking. Such shells are most easily detected in Na I absorption lines. The distance of the shell from the SN can be determined by measuring the timescale for line variability. Burns, Christopher R. We introduce a new light-curve parameter very similar to stretch that is better suited for fast-declining events, and find that these peculiar types can be seen as extensions to the population of 'normal' SNe Ia.

With a larger number of objects, an updated fit to the Lira relation is presented along with evidence for a dependence on the late-time slope of the B — V light-curves with stretch and color. The photometric data continue to favor low values of R V , though with large variations from event to event, indicating an intrinsic distribution. We confirm the findings of other groups that there appears to be a correlation between the derived reddening law, R V , and the color excess, E B — V , such that larger E B — V tends to favor lower R V. The intrinsic u-band colors show a relatively large scatter that cannot be explained by variations in R V or by the Goobar power-law for circumstellar dust, but rather is correlated with spectroscopic features of the supernova and is therefore likely due to metallicity effects.

Recent observational and theoretical progress has favored merging and helium-accreting sub-Chandrasekhar mass white dwarfs WDs in the double-degenerate and the double-detonation channels, respectively, as the most promising progenitors of normal Type Ia supernovae SNe Ia. Thus the fate of rapidly accreting Chandrasekhar mass WDs in the single-degenerate channel remains more mysterious then ever. In this paper, we clarify the nature of ignition in Chandrasekhar-mass single-degenerate SNe Ia by analytically deriving the existence of a characteristic length scale which establishes a transition from central ignitions to buoyancy-driven ignitions.

Using this criterion, combined with data from three-dimensional simulations of convection and ignition, we demonstrate that the overwhelming majority of ignition events within Chandrasekhar-mass WDs in the single-degenerate channel are buoyancy-driven, and consequently lack a vigorous deflagration phase. We establish that the rates predicted from both the population of supersoft X-ray sources SSSs and binary population synthesis models of the single-degenerate channel are broadly consistent with the observed rates of overluminous SNe Ia , and suggest that the population of SSSs are the dominant stellar progenitors of SNe T-like events.

We conclude with a range of observational tests of overluminous SNe Ia which will either support or strongly constrain the single-degenerate scenario. However, the post-maximum behavior of other UV-bright SNe Ia can also be modeled in a similar manner, including objects with UV spectroscopy or pre-maximum photometry which is inconsistent with this model. This suggests that similar UV luminosities can be intrinsic or caused by other forms of shock interaction.

The effect of peculiar velocities on supernova cosmology. We analyze the effect that peculiar velocities have on the cosmological inferences we make using luminosity distance indicators, such as Type Ia supernovae. In particular we study the corrections required to account for 1 our own motion, 2 correlations in galaxy motions, and 3 a possible lo Correcting supernova SN redshifts for the cosmic microwave background CMB dipole slightly overcorrects Type Ia supernovae, standardizable candles, and gravity. Type Ia supernovae SNe Ia are generally accepted to act as standardizable candles, and their use in cosmology led to the first confirmation of the as yet unexplained accelerated cosmic expansion.

Many of the theoretical models to explain the cosmic acceleration assume modifications to Einsteinian general relativity which accelerate the expansion, but the question of whether such modifications also affect the ability of SNe Ia to be standardizable candles has rarely been addressed. This paper is an attempt to answer this question. For this we adopt a semianalytical model to calculate SNe Ia light curves in non-standard gravity. We use this model to show that the average rescaled intrinsic peak luminosity—a quantity that is assumed to be constant with redshift in standard analyses of Type Ia supernova SN Ia cosmology data—depends on the strength of gravity in the supernova's local environment because the latter determines the Chandrasekhar mass—the mass of the SN Ia 's white dwarf progenitor right before the explosion.

This means that SNe Ia are no longer standardizable candles in scenarios where the strength of gravity evolves over time, and therefore the cosmology implied by the existing SN Ia data will be different when analysed in the context of such models. Huterer, Dragan; Shafer, Daniel L. Peculiar velocities of objects in the nearby universe are correlated due to the gravitational pull of large-scale structure.

By measuring these velocities, we have a unique opportunity to test the cosmological model at the lowest redshifts. We perform this test, using current data to constrain the amplitude of the ''signal'' covariance matrix describing the velocities and their correlations. We consider a new, well-calibrated ''Supercal'' set of low-redshift SNe Ia as well as a set of distances derived from the fundamental plane relation of 6dFGS galaxies.

Uddin, Syed A. We study the variation of these relationships with redshift and detect no evolution. We split SNe Ia into pairs of subsets that are based on the properties of the hosts and fit cosmological models to each subset. Including both systematic and statistical uncertainties, we do not find any significant shift in the best-fit cosmological parameters between the subsets. Impact of cosmic inhomogeneities on SNe observations. We study the impact of cosmic inhomogeneities on the interpretation of SNe observations. We build an inhomogeneous universe model that can confront supernova data and yet is reasonably well compatible with the Copernican Principle.

Our model combines a relatively small local void, that gives apparent acceleration at low redshifts, with a meatball model that gives sizeable lensing dimming at high redshifts. Together these two elements, which focus on different effects of voids on the data, allow the model to mimic the concordance model. Clues on Type Ia Supernovae Progenitors. We show that in the framework of canonical stellar evolution it is hard, if not impossible, to determine the growth in mass of a CO White Dwarf, up to the Chandrasekhar limit by means of mass transfer from its companion in a binary system.

This is the case either if matter is accreted from a normal companion with an H-rich envelope or if direct CO accretion occurs from a CO WD companion. At variance, we show that if the effects of rotation are taken into account in modeling the accretion process, a CO WD can increase its mass at the expenses of the degenerate CO companion up and beyond 1. In such a case the internal spread in the observational properties of type Ia SNe may be interpreted as a consequence of different total masses; hence differences between SNe Ia in nearby elliptical galaxies and the majority of those in spirals should be expected and the current use of type Ia SNe as cosmological distance indicators should be justified.

To understand how best to use observations of Type Ia supernovae SNe Ia to obtain precise and accurate distances, we investigate the relations between spectra of SNe Ia and their intrinsic colors. Ca II H and K does not have a linear relation with intrinsic color, but lower-velocity SNe tend to be intrinsically bluer. Combining the spectroscopic measurements does not improve intrinsic color inference. The intrinsic color scatter is larger for higher-velocity SNe Ia—even after removing a linear trend with velocity—indicating that lower-velocity SNe Ia are more 'standard crayons'.

Employing information derived from SN Ia spectra has the potential to improve the measurements of extragalactic distances and the cosmological properties inferred from them. Truran, James W. The utility of Type Ia supernovae, not simply as probes of the distance scale but also as a means of constraining the properties of dark energy, demands a significant improvement in theoretical predictions of their properties in outburst.

To this end, we have given substantial effort to quantifying the energetics and nucleosynthesis properties of deflagration fronts in the interiors of the putative carbon-oxygen white dwarf progenitors of Type Ia thermonuclear supernovae. We briefly review some essential features of our flame model and its properties in this paper and discuss its implications both for our multidimensional numerical simulations of SNe Ia and for nucleosynthesis specifically 56Ni production in SNe Ia and Galactic chemical evolution.

Testing cosmic transparency with the latest baryon acoustic oscillations and type Ia supernovae data. It has been suggested that this observed phenomenon can also be explained using light absorption instead of dark energy. Thus, cosmic opacity is not sufficient to account for the present observations and dark energy or modified gravity is still required. The birthrate from this channel would be too low to account for all observed SNe Ia were it not for some mechanism to enhance the rate of accretion on to the white dwarf. A tidally enhanced stellar wind, of the type which has been postulated to explain many phenomena related to giant star evolution in binary systems, can do this.

Compared to mass stripping, this model extends the space of SNe Ia progenitors to longer orbital periods and hence increases the birthrate to about 0. Two symbiotic stars, T CrB and RS Oph, considered to be the most likely progenitors of SNe Ia through the symbiotic channel, are well inside the period-companion mass space predicted by our models.

Due to their extreme luminosities at maximum light, type Ia supernovae SNe Ia have long been considered among the most attractive cosmological standard candles. Although nearly all work to date has been devoted to attempts to use these objects to determine the local rate of expansion of the universe Ho , SNe Ia also provide one of the few direct techniques for measuring the deceleration parameter qo. Such a range in peak luminosity could introduce a subtantial Malmquist bias into searches for distant z rate of the B light curve.

Interestingly, the most luminous SNe in our sample all occurred in spiral galaxies, which is true for Phillips' sample of nearby SNe Ia as well. This is opposite to what one would expect if dust extinction were important. These findings are consistent with recent speculations that the progenitors of SNe Ia are white dwarfs covering a range of masses, and also suggest that the brightest events may be found in galaxies which are still actively forming stars. The implications for the use of SNe Ia to measure qo are briefly discussed. Stritzinger, Maximilian D.

Presented here is the second data release of nearby SN Ia photometry consisting of 50 objects, with a subset of 45 having near-infrared follow-up observations. Thirty-three objects have optical pre-maximum coverage with a subset of 15 beginning at least five days before maximum light. In the near-infrared, 27 objects have coverage beginning before the epoch of B-band maximum, with a subset of 13 beginning at least five days before maximum. Theoretical uncertainties of the Type Ia supernova rate.

Two main evolutionary channels are proposed for the WD to reach the critical density required for a thermonuclear explosion: the single degenerate SD scenario, in which a CO WD accretes from a. We construct a hierarchical Bayesian framework, incorporating several uncertainties including photometric error, peculiar velocities, dust extinction, and intrinsic variations, for principled and coherent statistical inference.

SN Ia light-curve inferences are drawn from the global posterior probability of parameters describing both individual supernovae and the population conditioned on the entire SN Ia NIR data set. The logical structure of the hierarchical model is represented by a directed acyclic graph. Fully Bayesian analysis of the model and data is enabled by an efficient Markov Chain Monte Carlo algorithm exploiting the conditional probabilistic structure using Gibbs sampling.

A new light-curve model captures the observed J-band light-curve shape variations. We describe the first quantitative evidence for correlations between the NIR absolute magnitudes and J-band light-curve shapes, and demonstrate their utility for distance estimation. The new application of bootstrap cross-validation to SN Ia light-curve inference tests the sensitivity of the statistical model fit to the finite sample and estimates the prediction error at 0.

These results demonstrate that SN Ia NIR light curves are as effective as corrected optical light curves, and, because they are less vulnerable to dust absorption, they have great potential as precise and accurate cosmological distance indicators. Despite the importance of thermonuclear or Type Ia supernovae SNe as standard candles in astrophysics, the physical mechanisms behind Type Ia SNe are still poorly constrained. Theoretically, the nucleosynthetic yields from Type Ia SNe can distinguish among different models of Type Ia explosions.

For example, neutron-rich elements such as manganese Mn are sensitive probes of the physics of Type Ia SNe because their abundances are correlated to the density of the progenitor white dwarf. Since dwarf galaxies' chemical evolution is dominated by Type Ia SNe at late times, Type Ia nucleosynthetic yields can be indirectly inferred from stellar abundances in dwarf galaxies. However, previous measurements of Mn in dwarf galaxies are too incomplete to draw definitive conclusions on the Type Ia explosion mechanism. We report average Type Ia Mn yields computed from these abundances, and we discuss the implications for Type Ia supernova physics.

The spectacular success of Type Ia supernovae SNe Ia in SN-cosmology is based on the assumption that their photometric and spectroscopic properties are invariant with redshift. However, this fundamental assumption needs to be tested with observations of high-z SNe Ia. To date, the majority of SNe Ia observed at moderate to large redshifts 0. In rare cases, however, the Universe offers a helping hand: To date a few SNe Ia have been observed that have had their luminosities magnified by intervening galaxies and galaxy clusters acting as gravitational lenses.

Two populations of progenitors for Type Ia supernovae? We use recent observations of the evolution of the Type Ia supernova SN Ia rate with redshift, the dependence of the SN Ia rate on the colours of the parent galaxies, and the enhancement of the SN Ia rate in radio-loud early-type galaxies to derive on robust empirical grounds, the delay time distribution DTD between the formation of the progenitor star and its explosion as an SN.

We discuss the cosmological implications of this result and make simple predictions, which are testable with future instrumentation. Type Ia supernovae SNe Ia play an important role in the study of cosmic evolution, especially in cosmology. There are several progenitor models for SNe Ia proposed in the past years. According to these calculations, we mapped out the initial and final parameters for SNe Ia in the orbital period-secondary mass log P i - M i 2 plane for various WD masses for this channel.

We discussed the influence of the variation of the duty cycle value on the regions for producing SNe Ia. Similar to previous studies, this work also indicates that the long-period dwarf novae offer possible ways for producing SNe Ia. Meanwhile, we find that the surviving companion stars from this channel have a low mass after the SN explosion, which may provide a means for the formation of the population of single low-mass WDs o-dot.

Double-detonation model of type Ia supernovae with a variable helium layer ignition mass. Although Type Ia supernovae SNe Ia play an important role in the study of cosmology, their progenitors are still poorly understood. Thermonuclear explosions from the helium double-detonation sub-Chandrasekhar mass model have been considered as an alternative method for producing SNe Ia. By adopting the assumption that a double detonation occurs when a He layer with a critical ignition mass accumulates on the surface of a carbon—oxygen white dwarf CO WD , we perform detailed binary evolution calculations for the He double-detonation model, in which a He layer from a He star accumulates on a CO WD.

According to these calculations, we obtain the initial parameter spaces for SNe Ia in the orbital period and secondary mass plane for various initial WD masses. We implement these results into a detailed binary population synthesis approach to calculate SN Ia birthrates and delay times. This indicates that the double-detonation model only produces part of the SNe Ia. The metallicity of a star strongly affects both its evolution and the properties of the stellar remnant that results from its demise. However, it is often tacitly assumed that metallicity has no effect on the rate of SNe Ia.

We propose that a consequence of the effects of metallicity is to significantly increase the SN Ia rate in lower-metallicity galaxies, in contrast to previous expectations. This is because lower-metallicity stars leave behind higher-mass white dwarfs, which should be easier to bring to explosion. We first model SN Ia rates in relation to galaxy masses and ages alone, finding that the elevation in the rate of SNe Ia in lower-mass galaxies measured by Lick Observatory SN Search is readily explained.

However, we then see that models incorporating this effect of metallicity agree just as well. We suggest that this degeneracy warrants more detailed examination of host galaxy metallicities. Kistler, Matthew D. Using the same parameters to estimate the cosmic SN Ia rate, we again find good agreement with data up to z Almost-Equal-To 2. However, only one, iPTF16geu, has been found to date, and many more are needed to achieve these goals. To increase the multiply imaged SN Ia discovery rate, we present a simple algorithm for identifying gravitationally lensed SN Ia candidates in cadenced, wide-field optical imaging surveys.

Importantly, this purely photometric method does not require the ability to resolve the lensed images for discovery. Active galactic nuclei, the primary sources of contamination that affect the method, can be controlled using catalog cross-matches and color cuts. Highly magnified core-collapse SNe will also be discovered as a byproduct of the method. Using a Monte Carlo simulation, we forecast that the Large Synoptic Survey Telescope can discover up to multiply imaged SNe Ia using this technique in a 10 year z -band search, more than an order of magnitude improvement over previous estimates.

We also predict that the Zwicky Transient Facility should find up to 10 multiply imaged SNe Ia using this technique in a 3 year R -band search—despite the fact that this survey will not resolve a single system. The SN Ia sample was originally used by Wang et al.

Together, this evidence indicates a difference in intrinsic color for the subsamples. Accounting for this intrinsic color difference reduces the scatter in Hubble residuals from 0. We explain the correlation between ejecta velocity and color as increased line blanketing in the High-Velocity SNe Ia , causing them to become redder. We discuss some implications of this result, and stress the importance of spectroscopy for future SN Ia cosmology surveys, with particular focus on the design of WFIRST.

Goldstein, Daniel A. SNE 's methodological basis - web-based software in entrepreneurial surveys. This overhead based paper gives an introduction to the research methodology applied in the surveys carried out in the SNE -project The model of pulsar emission through superluminally induced polarization currents, SLIP , predicts that pulsations produced by such currents at many light cylinder radii by a rotating, magnetized body, will drive pulsations close to the axis of rotation. The axially driven pulsations enforce a toroidal geometry onto all early SNRs, rendering even SNe Ia unsuitable as standard candles.

The numbers for Sco X-1's jet are identical, while those for SS are lower 0. Type Ia supernovae SNe Ia are valuable distance indicators for cosmology and the elements they eject are are important for nucleosynthesis. They appear to be thermonuclear disruptions of carbon-oxygen white dwarfs that accrete from companion stars until they approach the Chandrasekbar mass, and there is a suspicion that the propagation of the nuclear burning front involves a transition from a deflagration to a detonation.

Comparison of synthetic and observed spectra provides information on the temperature, density, velocity, and composition of the ejected matter and thus constrain hydrodynamical models. In addition, the expanding photosphere method yields distances to individual events that are independent of distances based on the decay of 56Ni in SNe Ia and of Cepheid variable stars in the parent galaxies.

This thesis is broken down into 4 major sections, each highlighting a different way with which to use spectrum synthesis to analyze SNe Ia. Chapter 4 examines spectral correlations with luminosity in SNe Ia and provides a plausible explanation for these correlations via spectrum synthesis. Cataclysmic Variables as Supernova Ia Progenitors. Directory of Open Access Journals Sweden. Full Text Available Although the identification of the progenitors of type Ia supernovae SNeIa remains controversial, it is generally accepted that they originate from binary star systems in which at least one component is a carbon-oxygen white dwarf WD; those systems are grouped under the wide umbrella of cataclysmic variables.

However, the specifics of this scenario are far from being understood or defined, allowing for a wealth of theories fighting for attention and a dearth of observations to support them. I discuss the latest attempts to identify and study those controversial SNeIa progenitors.

I also introduce the most promising progenitor in hand and I present observational diagnostics that can reveal more members of the category. Elemental gas-phase abundances of intermediate redshift type Ia supernova star-forming host galaxies. Moreno-Raya, M. The maximum luminosity of type Ia supernovae SNe Ia depends on the oxygen abundance of the regions of the host galaxies, where they explode.

This metallicity dependence reduces the dispersion in the Hubble diagram HD when included with the traditional two-parameter calibration of SN Ia light-curve parameters and absolute magnitude. We also derive electronic temperature with the direct method for a small fraction of objects for consistency. We find a trend of decreasing oxygen abundance with increasing redshift for the most massive galaxies. Moreover, we study the dependence of the HD residuals HR with galaxy oxygen abundance obtaining a correlation in line with those found in other works.

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In particular, the HR versus oxygen abundance shows a slope of This implies smaller distance modulii after corrections for SNe Ia in metal-rich galaxies. Based on our previous results on local SNe Ia , we propose this dependence to be due to the lower luminosity of the SNe Ia produced in more metal-rich environments. For ejecta whose outer parts have a power-law density structure, we compare synchrotron emission with radio observations. This conclusion also holds if the progenitor of SN J was a rigidly rotating white dwarf WD with a main-sequence MS or red giant companion. However, if the tenuous medium is due to a recurrent nova, it is difficult from our model to predict synchrotron luminosities.

Although the formation channels of SNe fe and J are not clear, the null detection in radio wavelengths could point toward a low amplification efficiency for magnetic fields in SN shocks. Gonzalez-Gaitan, S. We use the aggregate light curves of spectroscopic and photometrically identified SNe Ia to fit the rising part of the light curve with a simple quadratic model. We obtain a light curve shape corrected, i. We search for variations among different populations, particularly subluminous objects, by dividing the sample in stretch. Our conclusions are the same for the single-stretch and two-stretch parameterizations of the light curve.

Brown, Peter J. The effect of metallicity on the observed light of Type Ia supernovae SNe Ia could lead to systematic errors as the absolute magnitudes of local and distant SNe Ia are compared to measure luminosity distances and determine cosmological parameters.

The UV light may be especially sensitive to metallicity, though different modeling methods disagree as to the magnitude, wavelength dependence, and even the sign of the effect. We find that the scatter in the mid-UV to near-UV colors is larger than predicted by changes in metallicity alone and is not consistent with reddening. We demonstrate that a recently employed method to determine relative abundances using UV spectra can be done using UVOT photometry, but we warn that accurate results require an accurate model of the cause of the variations.

The abundance of UV photometry now available should provide constraints on models that typically rely on UV spectroscopy for constraining metallicity, density, and other parameters. Nevertheless, UV spectroscopy for a variety of supernova explosions is still needed to guide the creation of accurate models.

A better understanding of the influences affecting the UV is important for using SNe Ia as cosmological probes, as the UV light may test whether SNe Ia are significantly affected by evolutionary effects. The outer density structure, 56Ni, and to a lesser degree asphericity, also impact the UV. The outer density structure, 56 Ni, and to a lesser degree asphericity, also impact the UV. Is there a main channel for the production of SNe Ia? If so, are these elusive progenitors single degenerate or double degenerate systems?

Although most participants seemed to favor the single degenerate channel, there was no general agreement on the type of binary system at play. An observational puzzle that was highlighted was the apparent paucity of supersoft sources in our Galaxy and also in external galaxies. The single degenerate channel and as it was pointed out, quite possibly also the double degenerate channel requires the binary system to pass through a phase of steady nuclear burning.

However, the observed number of supersoft sources falls short by a factor of up to in explaining the estimated birth rates of SNe Ia. Thus, are these supersoft sources somehow hidden away and radiating at different wavelengths, or are we missing some important pieces of this puzzle that may lead to the elimination of a certain class of progenitor?

Another unanswered question concerns the dependence of SNe Ia luminosities on the age of their host galaxy. Several hypotheses were put forward, but none was singled out as the most likely explanation. It is fair to say that at the end of the symposium the definitive answer to the vexed progenitor question remained well and truly wide open. Wang, X. Applying such an absorption-correction dichotomy to SNe Ia of these two groups remarkably reduces the dispersion in their peak luminosity from 0. This sample can then be compared with the existing 18 SN Ia distances from Cepheids. Through these comparisons, we will determine if there are any discrepancies between the SBF distance scale, which is extended into the Hubble flow using early-type galaxies, and the SNIa distance scale, for which local calibrators are scarce and host galaxy types and SN environments are heterogenous.

Since recent measurements of UV-optical colors suggest that SN Ia properties do depend on galaxy type and environment, it is essential that SNe Ia in all galaxy types are included when extending SN Ia distances to the distant Hubble flow. Since the conclusion that universal expansion is accelerating was originally based on SNe Ia distances, and because recent measurements of UV-optical colors suggest that SN Ia properties do depend on galaxy type and environment, it is essential to measure the same types of SNe in the same types of galaxies.

SBF is the only distance measurement technique with statistical uncertainties comparable to SN Ia that can be applied to the early-type of galaxies in which the majority of the high-redshift SNIa occur. Type Ia supernovae SNe Ia ; exploding white-dwarf stars were the key to the Nobel-worthy discovery and subsequent verification that the expansion of the Universe is accelerating, driven by the effects of dark energy. Understanding the nature of this mysterious, yet dominant, component of the Universe is at the forefront of research in cosmology and fundamental physics.

SNe Ia will continue to play a leading role in this enterprise, providing precise cosmological distances that improve constraints on the nature of dark energy. However, for this effort to succeed, we need to more thoroughly understand relatively nearby SNe Ia , because our conclusions come only from comparisons between them and distant high-redshift SNe Ia. Thus, detailed studies of relatively nearby SNe Ia are the focus of this research program. Many interesting results were obtained during the course of this project; these were published in 32 refereed research papers that acknowledged the grant.

We have determined the most accurate rates for SNe of different types in large, nearby galaxies in the present-day Universe, and these can be compared with SN rates far away and hence long ago in the past to set constraints on the types of stars that explode. Another major accomplishment was the publication of the light curves brightness vs. We have conducted intensive investigations of a number of individual SNe Ia , including quite unusual examples that allow us to probe the entire range of SN explosions and provide unique insights into these objects and the stars before they explode.

My team's studies have also. Peculiar Supernovae. What makes a supernova truly " peculiar? Type II proposed by Minkowski Publ. A handful of noteworthy examples are highlighted to illustrate a general theme: classes of supernovae that were once thought to be peculiar are later seen as logical branches of standard events. This is not always the case, however, and we discuss ASASSNlh as an example of a transient with an origin that remains contentious.

We remark on how late-time observations at all wavelengths radio-through-X-ray that probe 1 the kinematic and chemical properties of the supernova ejecta and 2 the progenitor star system's mass loss in the terminal phases preceding the explosion, have often been critical in understanding the nature of seemingly unusual events. The identity of the progenitor systems of type- Ia supernovae SNe Ia is a major unsolved problem in astrophysics. SN Ia rates are providing some striking clues.

We review the basics of SN rate measurement, preach about some sins of SN rate measurement and analysis, and illustrate one of these sins with an analogy about Martian scientists. We review the recent progress in measuring SN Ia rates in various environments and redshifts, and their use to reconstruct the SN Ia delay-time distribution DTD - the SN rate versus time that would follow a hypothetical brief burst of star formation.

A good number of DTD measurements, using a variety of methods, appear to be converging. The DTD peaks at the shortest delays probed. This result supports the idea of a double-degenerate progenitor origin for SNe Ia. Single-degenerate progenitors may still play a role in producing short-delay SNe Ia , or perhaps all SNe Ia , if the red-giant donor channel is more efficient than is found by most theoretical models. We point to some future directions that should lead to progress in the field, including measurement of the bivariate delay and stretch SN Ia response function.

The sample of low-redshift type Ia supernovae SNe Ia with 0. We show that the LF of SNe Ia host galaxies matches well with that of galaxies in the general field, suggesting that the occurrence of SNe Ia does not favor a particular type of galaxy but is predominantly proportional to the luminosity of galaxies. The evidence is weak that the SNe rate varies with the color of host galaxies.

In our low-redshift sample, the component of type Ia SN rate that is proportional to star formation activity is not evident in the integrated SN rate, while our observation is compatible with the current two-component models. The sample contains eight SNe Ia whose host galaxies were not identified, but it is shown that their occurrence is consistent with them occurring in low-luminous galaxies beyond the survey. The Gaussian distribution becomes tighter if the ratio of extinction to reddening, R V , is lower than the characteristic value for the Milky Way and if luminosity is corrected for the light-curve shape.

This color excess does not vary with the distance of the SNe from the center of the host galaxy to 15 kpc. This suggests that the major part of the color excess appears to be either intrinsic or reddening that arises in the immediate environment of SNe , rather than interstellar.