Low tropical diversity during the adaptive radiation of early land plants.

The latitudinal biodiversity gradient, with tropical regions acting as 'evolutionary cradles', is a cornerstone of current biogeographical and ecological theory1. In the modern world floral biodiversity and biomass are overwhelmingly concentrated in the tropics, and it is often assumed that the tropics were evolutionary cradles throughout land plant evolutionary history. For example, the origination and diversification of angiosperms is believed to have taken place in the Cretaceous tropics2 and modern gymnosperms in the Permian tropics3. Here, we show that during the first major diversification of land plants, in the Late Silurian-Early Devonian, land plant biodiversity was much lower at the equator compared to medium-high southern latitudes. Throughout this crucial interval of plant evolution, tropical vegetation remained depauperate and of very low taxonomic biodiversity, although with similar morphological disparity to the more diverse higher latitude floras. Possible explanations for this low tropical floral biodiversity include palaeocontinental configuration or adverse palaeotropical environmental conditions. We discount the possibility that it was simply a fortuitous feature of the biogeographical spread of the earliest vascular land plants.National Geographi

Efficient recycling strategies for preparing large Fock states from single-photon sources: Applications to quantum metrology

© 2016 American Physical Society. Fock states are a fundamental resource for many quantum technologies such as quantum metrology. While much progress has been made in single-photon source technologies, preparing Fock states with a large photon number remains challenging. We present and analyze a bootstrapped approach for nondeterministically preparing large photon-number Fock states by iteratively fusing smaller Fock states on a beamsplitter. We show that by employing state recycling we are able to exponentially improve the preparation rate over conventional schemes, allowing the efficient preparation of large Fock states. The scheme requires single-photon sources, beamsplitters, number-resolved photodetectors, fast-feedforward, and an optical quantum memory

Prospects for finding the mechanisms of sex differences in addiction with human and model organism genetic analysis.

Despite substantial evidence for sex differences in addiction epidemiology, addiction-relevant behaviors and associated neurobiological phenomena, the mechanisms and implications of these differences remain unknown. Genetic analysis in model organism is a potentially powerful and effective means of discovering the mechanisms that underlie sex differences in addiction. Human genetic studies are beginning to show precise risk variants that influence the mechanisms of addiction but typically lack sufficient power or neurobiological mechanistic access, particularly for the discovery of the mechanisms that underlie sex differences. Our thesis in this review is that genetic variation in model organisms are a promising approach that can complement these investigations to show the biological mechanisms that underlie sex differences in addiction

An Exactly Solvable Model for the Integrability-Chaos Transition in Rough Quantum Billiards

A central question of dynamics, largely open in the quantum case, is to what extent it erases a system's memory of its initial properties. Here we present a simple statistically solvable quantum model describing this memory loss across an integrability-chaos transition under a perturbation obeying no selection rules. From the perspective of quantum localization-delocalization on the lattice of quantum numbers, we are dealing with a situation where every lattice site is coupled to every other site with the same strength, on average. The model also rigorously justifies a similar set of relationships recently proposed in the context of two short-range-interacting ultracold atoms in a harmonic waveguide. Application of our model to an ensemble of uncorrelated impurities on a rectangular lattice gives good agreement with ab initio numerics.Comment: 29 pages, 5 figure

Variable Baseline Papio cynocephalus Endogenous Retrovirus (PcEV) Expression Is Upregulated in Acutely SIV-Infected Macaques and Correlated to STAT1 Expression in the Spleen

Retroviral replication leaves a DNA copy in the host cell chromosome, which over millions of years of infection of germline cells has led to 5% of the human genome sequence being comprised of endogenous retroviruses (ERVs), distributed throughout an estimated 100,000 loci. Over time these loci have accrued mutations such as premature stop codons that prevent continued replication. However, many loci remain both transcriptionally and translationally active and ERVs have been implicated in interacting with the host immune system. Using archived plasma and tissue samples from past macaque studies, experimentally infected with simian immunodeficiency virus (SIV), the expression of one macaque ERV in response to acute viral infection was explored together with a measure of the innate immune response. Specifically, RNA levels were determined for (a) Papio cynocephalus Endogenous Retrovirus (PcEV), an ERV (b) STAT1, a key gene in the interferon signaling pathway, and (c) SIV, an exogenous pathogen. Bioinformatic analysis of DNA sequences of the PcEV loci within the macaque reference genome revealed the presence of open reading frames (ORFs) consistent with potential protein expression but not ERV replication. Quantitative RT-PCR analysis of DNase-treated RNA extracts from plasma derived from acute SIV-infection detected PcEV RNA at low levels in 7 of 22 macaques. PcEV RNA levels were significantly elevated in PBMC and spleen samples recovered during acute SIV infection, but not in the thymus and lymph nodes. A strong positive correlation was identified between PcEV and STAT1 RNA levels in spleen samples recovered from SIV-positive macaques. One possibility is that SIV infection induces PcEV expression in infected lymphoid tissue that contributes to induction of an antiviral response

Associations between age and sleep apnea risk among newborn infants

ObjectiveAmong older children, sleep‐disordered breathing (SDB) is associated with measurable neurocognitive consequences. However, diagnostic SDB thresholds are lacking for infants < 12 months. We sought to evaluate the relationship between SDB indices, gestational age (GA), and postmenstrual age (PMA) for infants who underwent clinically‐indicated polysomnograms at a tertiary care center.MethodsEvery infant < 3‐months chronological age whose first clinically‐indicated polysomnogram was between 2/2012 and 2/2017 was included. Linear regression was used to evaluate associations between apnea‐hypopnea index (AHI), obstructive‐apnea index (OAI), and GA and PMA for infants with and without obvious clinical risk factors for SDB (eg, micrognathia and cleft palate).ResultsFor 53 infants without obvious SDB risk factors (GA 35.6 ± 4.5 weeks; PMA 41.2 ± 4.0 weeks), mean AHI was 27 ± 18 and OAI 2.9 ± 4.5. There was a weak inverse relationship between AHI and PMA (r2 = 0.12, P = 0.01), but AHI was not predicted by GA (r2 = 0.04, P = 0.13). Conversely, OAI was more strongly associated with GA (r2 = 0.33, P < 0.0001) than PMA (r2 = 0.08, P = 0.036). For 28 infants with congenital structural anomalies that predispose to SDB (GA 38.0 ± 3.1 weeks, PMA 43.1 ± 3.3 weeks, AHI 37.7 ± 30, OAI 8.2 ± 11.8), neither AHI nor OAI were related to PMA or GA.ConclusionsAmong infants who received clinically‐indicated polysomnograms but did not have obvious structural risk for SDB, AHI declined with advancing PMA, but obstructive‐apnea was best predicted by prematurity. In contrast, the SDB risk did not improve with increasing GA or PMA for infants with congenital structural risk factors; such infants may not outgrow their risk for SDB.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150552/1/ppul24354_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150552/2/ppul24354.pd

Abnormalities in autonomic function in obese boys at-risk for insulin resistance and obstructive sleep apnea.

Study objectivesCurrent evidence in adults suggests that, independent of obesity, obstructive sleep apnea (OSA) can lead to autonomic dysfunction and impaired glucose metabolism, but these relationships are less clear in children. The purpose of this study was to investigate the associations among OSA, glucose metabolism, and daytime autonomic function in obese pediatric subjects.MethodsTwenty-three obese boys participated in: overnight polysomnography; a frequently sampled intravenous glucose tolerance test; and recordings of spontaneous cardiorespiratory data in both the supine (baseline) and standing (sympathetic stimulus) postures.ResultsBaseline systolic blood pressure and reactivity of low-frequency heart rate variability to postural stress correlated with insulin resistance, increased fasting glucose, and reduced beta-cell function, but not OSA severity. Baroreflex sensitivity reactivity was reduced with sleep fragmentation, but only for subjects with low insulin sensitivity and/or low first-phase insulin response to glucose.ConclusionsThese findings suggest that vascular sympathetic activity impairment is more strongly affected by metabolic dysfunction than by OSA severity, while blunted vagal autonomic function associated with sleep fragmentation in OSA is enhanced when metabolic dysfunction is also present

Genome wide analysis of gene expression changes in skin from patients with type 2 diabetes

Non-healing chronic ulcers are a serious complication of diabetes and are a major healthcare problem. While a host of treatments have been explored to heal or prevent these ulcers from forming, these treatments have not been found to be consistently effective in clinical trials. An understanding of the changes in gene expression in the skin of diabetic patients may provide insight into the processes and mechanisms that precede the formation of non-healing ulcers. In this study, we investigated genome wide changes in gene expression in skin between patients with type 2 diabetes and non-diabetic patients using next generation sequencing. We compared the gene expression in skin samples taken from 27 patients (13 with type 2 diabetes and 14 non-diabetic). This information may be useful in identifying the causal factors and potential therapeutic targets for the prevention and treatment of diabetic related diseases