Spacetime Noncommutativity and Antisymmetric Tensor Dynamics in the Early Universe

This paper investigates the possible cosmological implications of the presence of an antisymmetric tensor field related to a lack of commutatitivity of spacetime coordinates at the Planck era. For this purpose, such a field is promoted to a dynamical variable, inspired by tensor formalism. By working to quadratic order in the antisymmetric tensor, we study the field equations in a Bianchi I universe in two models: an antisymmetric tensor plus scalar field coupled to gravity, or a cosmological constant and a free massless antisymmetric tensor. In the first scenario, numerical integration shows that, in the very early universe, the effects of the antisymmetric tensor can prevail on the scalar field, while at late times the former approaches zero and the latter drives the isotropization of the universe. In the second model, an approximate solution is obtained of a nonlinear ordinary differential equation which shows how the mean Hubble parameter and the difference between longitudinal and orthogonal Hubble parameter evolve in the early universe.Comment: 25 pages, Revtex file, 4 figures in attachmen

Massive stars exploding in a He-rich circumstellar medium - IX. SN 2014av, and characterization of Type Ibn SNe

We present spectroscopic and photometric data of the Type Ibn supernova (SN) 2014av, discovered by the Xingming Observatory Sky Survey. Stringent pre-discovery detection limits indicate that the object was detected for the first time about 4 d after the explosion. A prompt follow-up campaign arranged by amateur astronomers allowed us to monitor the rising phase (lasting 10.6 d) and to accurately estimate the epoch of the maximum light, on 2014 April 23 (JD = 245 6771.1 ± 1.2). The absolute magnitude of the SN at the maximum light is MR = −19.76 ± 0.16. The post-peak light curve shows an initial fast decline lasting about three weeks, and is followed by a slower decline in all bands until the end of the monitoring campaign. The spectra are initially characterized by a hot continuum. Later on, the temperature declines and a number of lines become prominent mostly in emission. In particular, later spectra are dominated by strong and narrow emission features of He I typical of Type Ibn supernovae (SNe), although there is a clear signature of lines from heavier elements (in particular O I, Mg II and Ca II). A forest of relatively narrow Fe II lines is also detected showing P-Cygni profiles, with the absorption component blueshifted by about 1200 km s−1. Another spectral feature often observed in interacting SNe, a strong blue pseudo-continuum, is seen in our latest spectra of SN 2014av. We discuss in this paper the physical parameters of SN 2014av in the context of the Type Ibn SN variety

Presynaptically Localized Cyclic GMP-Dependent Protein Kinase 1 Is a Key Determinant of Spinal Synaptic Potentiation and Pain Hypersensitivity

Electrophysiological and behavioral experiments in mice reveal that a cGMP-dependent kinase amplifies neurotransmitter release from peripheral pain sensors, potentiates spinal synapses, and leads to exaggerated pain

A meta-analysis of genome-wide data from five European isolates reveals an association of COL22A1, SYT1, and GABRR2 with serum creatinine level

<p>Abstract</p> <p>Background</p> <p>Serum creatinine (S_CR) is the most important biomarker for a quick and non-invasive assessment of kidney function in population-based surveys. A substantial proportion of the inter-individual variability in S_CRlevel is explicable by genetic factors.</p> <p>Methods</p> <p>We performed a meta-analysis of genome-wide association studies of S_CRundertaken in five population isolates ('discovery cohorts'), all of which are part of the European Special Population Network (EUROSPAN) project. Genes showing the strongest evidence for an association with S_CR(candidate loci) were replicated in two additional population-based samples ('replication cohorts').</p> <p>Results</p> <p>After the discovery meta-analysis, 29 loci were selected for replication. Association between S_CRlevel and polymorphisms in the collagen type XXII alpha 1 (<it>COL22A1</it>) gene, on chromosome 8, and in the synaptotagmin-1 (<it>SYT1</it>) gene, on chromosome 12, were successfully replicated in the replication cohorts (p value = 1.0 × 10^-6and 1.7 × 10^-4, respectively). Evidence of association was also found for polymorphisms in a locus including the gamma-aminobutyric acid receptor rho-2 (<it>GABRR2</it>) gene and the ubiquitin-conjugating enzyme E2-J1 (<it>UBE2J1</it>) gene (replication p value = 3.6 × 10^-3). Previously reported findings, associating glomerular filtration rate with SNPs in the uromodulin (<it>UMOD</it>) gene and in the schroom family member 3 (<it>SCHROOM3</it>) gene were also replicated.</p> <p>Conclusions</p> <p>While confirming earlier results, our study provides new insights in the understanding of the genetic basis of serum creatinine regulatory processes. In particular, the association with the genes <it>SYT1 </it>and <it>GABRR2 </it>corroborate previous findings that highlighted a possible role of the neurotransmitters GABA_Areceptors in the regulation of the glomerular basement membrane and a possible interaction between GABA_Areceptors and synaptotagmin-I at the podocyte level.</p

Massive stars exploding in a He-rich circumstellar medium - IX. SN 2014av, and characterization of Type Ibn SNe

We present spectroscopic and photometric data of the Type Ibn supernova (SN) 2014av, discovered by the Xingming Observatory Sky Survey. Stringent pre-discovery detection limits indicate that the object was detected for the first time about 4 d after the explosion. A prompt follow-up campaign arranged by amateur astronomers allowed us to monitor the rising phase (lasting 10.6 d) and to accurately estimate the epoch of the maximum light, on 2014 April 23 (JD = 245 6771.1 ± 1.2). The absolute magnitude of the SN at the maximum light is MR = -19.76 ± 0.16. The post-peak light curve shows an initial fast decline lasting about three weeks, and is followed by a slower decline in all bands until the end of the monitoring campaign. The spectra are initially characterized by a hot continuum. Later on, the temperature declines and a number of lines become prominent mostly in emission. In particular, later spectra are dominated by strong and narrow emission features of He I typical of Type Ibn supernovae (SNe), although there is a clear signature of lines from heavier elements (in particular O I, Mg II and Ca II). A forest of relatively narrow Fe II lines is also detected showing P-Cygni profiles, with the absorption component blueshifted by about 1200 km s-1. Another spectral feature often observed in interacting SNe, a strong blue pseudo-continuum, is seen in our latest spectra of SN 2014av. We discuss in this paper the physical parameters of SN 2014av in the context of the Type Ibn SN variety

Platelet Activating Factor Blocks Interkinetic Nuclear Migration in Retinal Progenitors through an Arrest of the Cell Cycle at the S/G2 Transition

Nuclear migration is regulated by the LIS1 protein, which is the regulatory subunit of platelet activating factor (PAF) acetyl-hydrolase, an enzyme complex that inactivates the lipid mediator PAF. Among other functions, PAF modulates cell proliferation, but its effects upon mechanisms of the cell cycle are unknown. Here we show that PAF inhibited interkinetic nuclear migration (IKNM) in retinal proliferating progenitors. The lipid did not, however, affect the velocity of nuclear migration in cells that escaped IKNM blockade. The effect depended on the PAF receptor, Erk and p38 pathways and Chk1. PAF induced no cell death, nor a reduction in nucleotide incorporation, which rules out an intra-S checkpoint. Notwithstanding, the expected increase in cyclin B1 content during G2-phase was prevented in the proliferating cells. We conclude that PAF blocks interkinetic nuclear migration in retinal progenitor cells through an unusual arrest of the cell cycle at the transition from S to G2 phases. These data suggest the operation, in the developing retina, of a checkpoint that monitors the transition from S to G2 phases of the cell cycle

DNA Barcode Sequence Identification Incorporating Taxonomic Hierarchy and within Taxon Variability

For DNA barcoding to succeed as a scientific endeavor an accurate and expeditious query sequence identification method is needed. Although a global multiple–sequence alignment can be generated for some barcoding markers (e.g. COI, rbcL), not all barcoding markers are as structurally conserved (e.g. matK). Thus, algorithms that depend on global multiple–sequence alignments are not universally applicable. Some sequence identification methods that use local pairwise alignments (e.g. BLAST) are unable to accurately differentiate between highly similar sequences and are not designed to cope with hierarchic phylogenetic relationships or within taxon variability. Here, I present a novel alignment–free sequence identification algorithm–BRONX–that accounts for observed within taxon variability and hierarchic relationships among taxa. BRONX identifies short variable segments and corresponding invariant flanking regions in reference sequences. These flanking regions are used to score variable regions in the query sequence without the production of a global multiple–sequence alignment. By incorporating observed within taxon variability into the scoring procedure, misidentifications arising from shared alleles/haplotypes are minimized. An explicit treatment of more inclusive terminals allows for separate identifications to be made for each taxonomic level and/or for user–defined terminals. BRONX performs better than all other methods when there is imperfect overlap between query and reference sequences (e.g. mini–barcode queries against a full–length barcode database). BRONX consistently produced better identifications at the genus–level for all query types