228 research outputs found
Random subspaces for encryption based on a private shared Cartesian frame
A private shared Cartesian frame is a novel form of private shared
correlation that allows for both private classical and quantum communication.
Cryptography using a private shared Cartesian frame has the remarkable property
that asymptotically, if perfect privacy is demanded, the private classical
capacity is three times the private quantum capacity. We demonstrate that if
the requirement for perfect privacy is relaxed, then it is possible to use the
properties of random subspaces to nearly triple the private quantum capacity,
almost closing the gap between the private classical and quantum capacities.Comment: 9 pages, published versio
A Cross-Sectional Study of Myopia and Morning Melatonin Status in Northern Irish Adolescent Children
Purpose. Previous studies have demonstrated an association between melatonin status and both refractive error and axial length in young adult myopes. This study aimed to determine if this relationship extends to a younger adolescent cohort. Methods. Healthy children aged 12–15 years provided morning saliva samples before attending Ulster University (55°N) for cycloplegic autorefraction and axial length measures. Participants completed questionnaires describing recent sleep habits and physical activity. Salivary melatonin was quantified using high-performance liquid chromatography-tandem mass spectrometry. Data collection for all participants occurred over a 1-week period (April 2021). Results. Seventy participants aged 14.3 (95% CI: 14.2—14.5) years were categorised by spherical equivalent refraction [SER] (range: −5.38DS to +1.88DS) into two groups; myopic SER ≤ −0.50DS (n = 22) or nonmyopic −0.50DS < SER ≤ +2.00DS (n = 48). Median morning salivary melatonin levels were 4.52 pg/ml (95% CI: 2.60–6.02) and 4.89 pg/ml (95% CI: 3.18–5.66) for myopic and nonmyopic subjects, respectively, and did not differ significantly between refractive groups ( = 0.91). Melatonin levels were not significantly correlated with SER, axial length, sleep, or activity scores (Spearman’s rank, all > 0.39). Higher levels of physical activity were associated with higher sleep quality (Spearman’s rank, ρ = −0.28, = 0.02). Conclusion. The present study found no significant relationship between morning salivary melatonin levels and refractive error or axial length in young adolescents. This contrasts with outcomes from a previous study of adults with comparable methodology, season of data collection, and geographical location. Prospective studies are needed to understand the discrepancies between adult and childhood findings and evaluate whether melatonin levels in childhood are indicative of an increased risk for future onset of myopia and/or faster axial growth trajectories and myopia progression in established myopes. Future work should opt for a comprehensive dim-light melatonin onset protocol to determine circadian phase
Recommended from our members
Does hydrologic circulation mask frictional heat on faults after large earthquakes?
Knowledge of frictional resistance along faults is important for understanding the
mechanics of earthquakes and faulting. The clearest in situ measure of fault friction
potentially comes from temperature measurements in boreholes crossing fault zones within a
few years of rupture. However, large temperature signals from frictional heating on faults
have not been observed. Unambiguously interpreting the coseismic frictional resistance
from small thermal perturbations observed in borehole temperature profiles requires
assessing the impact of other potentially confounding thermal processes. We address several
issues associated with quantifying the temperature signal of frictional heating including
transient fluid flow associated with the earthquake, thermal disturbance caused by borehole
drilling, and heterogeneous thermal physical rock properties. Transient fluid flow is
investigated using a two‐dimensional coupled fluid flow and heat transport model to
evaluate the temperature field following an earthquake. Simulations for a range of realistic
permeability, frictional heating, and pore pressure scenarios show that high permeabilities
(>10−14 m2) are necessary for significant advection within the several years after an
earthquake and suggest that transient fluid flow is unlikely to mask frictional heat anomalies.
We illustrate how disturbances from circulating fluids during drilling diffuse quickly
leaving a robust signature of frictional heating. Finally, we discuss the utility of repeated
borehole temperature profiles for discriminating between different interpretations of thermal
perturbations. Our results suggest that temperature anomalies from even low friction should
be detectable at depths >1 km 1 to 2 years after a large earthquake and that interpretations
of low friction from existing data are likely robust.Keywords: Frictional heat on faults, Hydrologic circulationKeywords: Frictional heat on faults, Hydrologic circulatio
Recommended from our members
Re-evaluation of heat flow data near Parkfield, CA: Evidence for a weak San Andreas Fault
Improved interpretations of the strength of the San
Andreas Fault near Parkfield, CA based on thermal data
require quantification of processes causing significant
scatter and uncertainty in existing heat flow data. These
effects include topographic refraction, heat advection by
topographically-driven groundwater flow, and uncertainty
in thermal conductivity. Here, we re-evaluate the heat flow
data in this area by correcting for full 3-D terrain effects. We
then investigate the potential role of groundwater flow in
redistributing fault-generated heat, using numerical models
of coupled heat and fluid flow for a wide range of
hydrologic scenarios. We find that a large degree of the
scatter in the data can be accounted for by 3-D terrain
effects, and that for plausible groundwater flow scenarios
frictional heat generated along a strong fault is unlikely to
be redistributed by topographically-driven groundwater
flow in a manner consistent with the 3-D corrected
data.Keywords: 8150 Tectonophysics: Plate boundary-general (3040), 8164 Tectonophysics: Stresses-crust and lithosphere, 8130 Tectonophysics: Heat generation and transpor
Dual-modality gene reporter for in vivo imaging
The ability to track cells and their patterns of gene expression in living organisms can increase our understanding of tissue development and disease. Gene reporters for bioluminescence, fluorescence, radionuclide, and magnetic resonance imaging (MRI) have been described but these suffer variously from limited depth penetration, spatial resolution, and sensitivity. We describe here a gene reporter, based on the organic anion transporting protein Oatp1a1, which mediates uptake of a clinically approved, Gd(3+)-based, hepatotrophic contrast agent (gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid). Cells expressing the reporter showed readily reversible, intense, and positive contrast (up to 7.8-fold signal enhancement) in T1-weighted magnetic resonance images acquired in vivo. The maximum signal enhancement obtained so far is more than double that produced by MRI gene reporters described previously. Exchanging the Gd(3+) ion for the radionuclide, (111)In, also allowed detection by single-photon emission computed tomography, thus combining the spatial resolution of MRI with the sensitivity of radionuclide imaging
Elevated cerebrospinal fluid 5-hydroxyindoleacetic acid in macaques following early life stress and inverse association with hippocampal volume: preliminary implications for serotonin-related function in mood and anxiety disorders
Background: Early life stress (ELS) is cited as a risk for mood and anxiety disorders, potentially through altered serotonin neurotransmission. We examined the effects of ELS, utilizing the variable foraging demand (VFD) macaque model, on adolescent monoamine metabolites. We sought to replicate an increase in cerebrospinal fluid (CSF) 5-hydroxyindoleacetic acid (5-HIAA) observed in two previous VFD cohorts. We hypothesized that elevated cisternal 5-HIAA was associated with reduced neurotrophic effects, conceivably due to excessive negative feedback at somatodendritic 5-HT1A autoreceptors. A putatively decreased serotonin neurotransmission would be reflected by reductions in hippocampal volume and white matter (WM) fractional anisotropy (FA).Methods: When infants were 2-6 months of age, bonnet macaque mothers were exposed to VFD. We employed cisternal CSF taps to measure monoamine metabolites in VFD (N = 22) and non-VFD (N = 14) offspring (mean age = 2.61 years). Metabolites were correlated with hippocampal volume obtained by MRI and WM FA by diffusion tensor imaging in young adulthood in 17 males [10 VFD (mean age = 4.57 years)].Results: VFD subjects exhibited increased CSF 5-HIAA compared to non-VFD controls. An inverse correlation between right hippocampal volume and 5-HIAA was noted in VFD- but not controls. CSF HVA and MHPG correlated inversely with hippocampal volume only in VFD. CSF 5-HIAA correlated inversely with FA of the VVM tracts of the anterior limb of the internal capsule (ALIC) only in VFD.Conclusions: Elevated cisternal 5-HIAA in VFD may reflect increased dorsal raphe serotonin, potentially inducing excessive autoreceptor activation, inducing a putative serotonin deficit in terminal fields. Resultant reductions in neurotrophic activity are reflected by smaller right hippocampal volume. Convergent evidence of reduced neurotrophic activity in association with high CSF 5-HIAA in VFD was reflected by reduced FA of the ALIC.NIMHSuny Downstate Med Ctr, Nonhuman Primate Lab, Dept Psychiat & Behav Sci, Brooklyn, NY 11203 USANew York State Psychiat Inst & Hosp, New York, NY 10032 USASuny Downstate Med Ctr, Coll Med, Brooklyn, NY 11203 USAUniversidade Federal de São Paulo, Dept Psychiat & Neuroradiol, São Paulo, BrazilFranklin Beha Hlh Consultants, Bronx, NY USANew York State Psychiat Inst & Hosp, Dept Mol Imaging & Neuropathol, New York, NY 10032 USAIcahn Sch Med Mt Sinai, Dept Psychiat, New York, NY 10029 USAIcahn Sch Med Mt Sinai, Dept Neurosci, New York, NY 10029 USAIcahn Sch Med Mt Sinai, Dept Radiol, New York, NY 10029 USAIcahn Sch Med Mt Sinai, Fishberg Dept Neurosci, New York, NY 10029 USAIcahn Sch Med Mt Sinai, Friedman Brain Inst, New York, NY 10029 USAYale Univ, Sch Med, Dept Psychiat, New Haven, CT USAMichael E Debakey VA Med Ctr, Mental Hlth Care Line, Houston, TX USABaylor Coll Med, Menninger Dept Psychiat & Behav Sci, Houston, TX 77030 USAYale Univ, Sch Med, Ctr Child Study, New Haven, CT 06510 USAUniversidade Federal de São Paulo, Dept Psychiat & Neuroradiol, São Paulo, BrazilNIMH: R21MH066748NIMH: R01 MH059990Web of Scienc
Discovery and Follow-up Observations of the Young Type Ia Supernova 2016coj
The Type~Ia supernova (SN~Ia) 2016coj in NGC 4125 (redshift ) was
discovered by the Lick Observatory Supernova Search 4.9 days after the fitted
first-light time (FFLT; 11.1 days before -band maximum). Our first detection
(pre-discovery) is merely day after the FFLT, making SN 2016coj one
of the earliest known detections of a SN Ia. A spectrum was taken only 3.7 hr
after discovery (5.0 days after the FFLT) and classified as a normal SN Ia. We
performed high-quality photometry, low- and high-resolution spectroscopy, and
spectropolarimetry, finding that SN 2016coj is a spectroscopically normal SN
Ia, but with a high velocity of \ion{Si}{2} 6355 (\,\kms\
around peak brightness). The \ion{Si}{2} 6355 velocity evolution can
be well fit by a broken-power-law function for up to a month after the FFLT. SN
2016coj has a normal peak luminosity ( mag), and it
reaches a -band maximum \about16.0~d after the FFLT. We estimate there to be
low host-galaxy extinction based on the absence of Na~I~D absorption lines in
our low- and high-resolution spectra. The spectropolarimetric data exhibit weak
polarization in the continuum, but the \ion{Si}{2} line polarization is quite
strong () at peak brightness.Comment: Submitte
Recommended from our members
A high-resolution map of human evolutionary constraint using 29 mammals.
The comparison of related genomes has emerged as a powerful lens for genome interpretation. Here we report the sequencing and comparative analysis of 29 eutherian genomes. We confirm that at least 5.5% of the human genome has undergone purifying selection, and locate constrained elements covering ∼4.2% of the genome. We use evolutionary signatures and comparisons with experimental data sets to suggest candidate functions for ∼60% of constrained bases. These elements reveal a small number of new coding exons, candidate stop codon readthrough events and over 10,000 regions of overlapping synonymous constraint within protein-coding exons. We find 220 candidate RNA structural families, and nearly a million elements overlapping potential promoter, enhancer and insulator regions. We report specific amino acid residues that have undergone positive selection, 280,000 non-coding elements exapted from mobile elements and more than 1,000 primate- and human-accelerated elements. Overlap with disease-associated variants indicates that our findings will be relevant for studies of human biology, health and disease
Kretzoiarctos gen. nov., the Oldest Member of the Giant Panda Clade
The phylogenetic position of the giant panda, Ailuropoda melanoleuca (Carnivora: Ursidae: Ailuropodinae), has been one of the most hotly debated topics by mammalian biologists and paleontologists during the last century. Based on molecular data, it is currently recognized as a true ursid, sister-taxon of the remaining extant bears, from which it would have diverged by the Early Miocene. However, from a paleobiogeographic and chronological perspective, the origin of the giant panda lineage has remained elusive due to the scarcity of the available Miocene fossil record. Until recently, the genus Ailurarctos from the Late Miocene of China (ca. 8–7 mya) was recognized as the oldest undoubted member of the Ailuropodinae, suggesting that the panda lineage might have originated from an Ursavus ancestor. The role of the purported ailuropodine Agriarctos, from the Miocene of Europe, in the origins of this clade has been generally dismissed due to the paucity of the available material. Here, we describe a new ailuropodine genus, Kretzoiarctos gen. nov., based on remains from two Middle Miocene (ca. 12–11 Ma) Spanish localities. A cladistic analysis of fossil and extant members of the Ursoidea confirms the inclusion of the new genus into the Ailuropodinae. Moreover, Kretzoiarctos precedes in time the previously-known, Late Miocene members of the giant panda clade from Eurasia (Agriarctos and Ailurarctos). The former can be therefore considered the oldest recorded member of the giant panda lineage, which has significant implications for understanding the origins of this clade from a paleobiogeographic viewpoint
- …