Manhattan orbifolds

We investigate a class of metrics for 2-manifolds in which, except for a discrete set of singular points, the metric is locally isometric to an L_1 (or equivalently L_infinity) metric, and show that with certain additional conditions such metrics are injective. We use this construction to find the tight span of squaregraphs and related graphs, and we find an injective metric that approximates the distances in the hyperbolic plane analogously to the way the rectilinear metrics approximate the Euclidean distance.Comment: 17 pages, 15 figures. Some definitions and proofs have been revised since the previous version, and a new example has been adde

Schöne neue Mathewelt – eine Klarstellung

Auch auf die Gefahr hin den Leser bzw. die Leserin mit einem weiteren Diskussionsbeitrag zur (österreichischen) Zentralmatura zu langweilen, fühlen wir uns verpflichtet, offensichtliche Missverständnisse im Artikel von Kühnel und Bandelt in Heft 102 auszuräumen

SEQUENCING AND COMPARATIVE ANALYSIS OF THE MITOCHONDRIAL CYTOCHROME B GENE IN THE MARION UPLANDS FLORIDA SAND SKINK (PLESTIODON REYNOLDSI)

The Florida sand skink (Plestiodon reynoldsi)—a small (~10 cm) lizard endemic to the peninsula—is a ‘sand-swimming’ specialist restricted to Florida scrub habitat on the state’s central highland ridges. Florida scrub has been severely fragmented through urban growth and citrus farming, and less than 10% of this ecosystem remains. Given the skink’s limited geographic range and extensive population fragmentation, P. reynoldsi was listed as a federally threatened species in 1987. I surveyed skink populations from the Marion Uplands, where suitable lizard habitat is naturally (and has been historically) isolated from scrub on nearby Mt. Dora and Lake Wales ridges. I wanted to determine genetic relatedness of Marion Uplands skinks to those inhabiting these two ridges and hypothesized that Marion populations should be more similar genetically to those on the Mt. Dora ridge, given their geographic proximity. Mitochondrial DNA sequence analysis confirmed this hypothesis but also revealed unexpectedly high levels of genetic divergence between the Marion and Mt. Dora populations. Indeed, observed genetic divergence was comparable to that detected between Marion and Lake Wales populations

Molecular phylogeny of the hominoids

Početci istraživanja ljudskog filogenetskog stabla su se zasnivali na subjektivnoj metodi koja je koristila morfološka obilježja za njegovu rekonstrukciju. U 20. st. genetika i molekularna biologija uvode ljudski genom kao osnovu istraživanja evolucijskih odnosa. Osnovne metode postaju DNA hibridizacija i sekvencioniranje genoma. Zahvaljujući tim metodama za našu najbližu sestrinsku grupu stavljamo čimpanze. Pažnja se posvećuje i manjim DNA sekvencama poput mitohondrijske DNA ili Y kromosoma. To nam je omogućilo ne samo bolji uvid u našu evolucijsku granu rodoslovnog stabla, već i praćenje ekspanzije ljudskih populacija kroz povijest. Korijen naše civilizacije se nalazi u Africi te se preko Europe i Azije širi u ostatak svijeta. To je potkrijepljeno i teorijom „out of Africa“ koja sugerira razvoj i ekspanziju modernih ljudi iz Afrike u ostatak svijeta. Danas se najveće polemike vode oko “karike koja nedostaje” i njenih dosad pronađenih kandidata.The beginning of scientific research of human phylogenetic tree was based upon the subjective method which applied morphologic characteristics for its reconstruction. In 20. century genetic and molecular biology introduced human genome as the base for evolution relationship research. DNA hybridization and genome sequencing became basic methods. Owing to those methods we put chimpanzee as our nearest sister group. We also put our focus on smaller DNA sequences such as mitochondrial DNA or Y chromosome. That provided not only a better insight to our evolution branch of human family tree, but also to track expansions of human populations during history. The root of our civilization lies in Africa and spreads over Europe and Asia to the rest of the world. That point of view is also supported by „out of Africa“ theory which suggested that modern humans developed in Africa and then spread to the rest of the world. Today, the biggest controversy is the “missing link” and the candidates that represent it