Regional coherence evaluation in mild cognitive impairment and Alzheimer's disease based on adaptively extracted magnetoencephalogram rhythms

This study assesses the connectivity alterations caused by Alzheimer's disease (AD) and mild cognitive impairment (MCI) in magnetoencephalogram (MEG) background activity. Moreover, a novel methodology to adaptively extract brain rhythms from the MEG is introduced. This methodology relies on the ability of empirical mode decomposition to isolate local signal oscillations and constrained blind source separation to extract the activity that jointly represents a subset of channels. Inter-regional MEG connectivity was analysed for 36 AD, 18 MCI and 26 control subjects in δ, θ, α and β bands over left and right central, anterior, lateral and posterior regions with magnitude squared coherence—c(f). For the sake of comparison, c(f) was calculated from the original MEG channels and from the adaptively extracted rhythms. The results indicated that AD and MCI cause slight alterations in the MEG connectivity. Computed from the extracted rhythms, c(f) distinguished AD and MCI subjects from controls with 69.4% and 77.3% accuracies, respectively, in a full leave-one-out cross-validation evaluation. These values were higher than those obtained without the proposed extraction methodology

Characterizing CO Fourth Positive Emission in Young Circumstellar Disks

Carbon Monoxide is a commonly used IR/sub-mm tracer of gas in protoplanetary disks. We present an analysis of ultraviolet CO emission in {HST}-COS spectra for 12 Classical T Tauri stars. Several ro-vibrational bands of the CO A^1\Pi - X^1\Sigma^+ (Fourth Positive) electronic transition system are spectrally resolved from emission of other atoms and H_2. The CO A^1\Pi v'=14 state is populated by absorption of Ly\alpha photons, created at the accretion column on the stellar surface. For targets with strong CO emission, we model the Ly\alpha radiation field as an input for a simple fluorescence model to estimate CO rotational excitation temperatures and column densities. Typical column densities range from N_{CO} = 10^{18} - 10^{19} cm^{-2}. Our measured excitation temperatures are mostly below T_{CO} = 600 K, cooler than typical M-band CO emission. These temperatures and the emission line widths imply that the UV emission originates in a different population of CO than that which is IR-emitting. We also find a significant correlation between CO emission and the disk accretion rate M_{acc} and age. Our analysis shows that ultraviolet CO emission can be a useful diagnostic of CTTS disk gas

The Far-Ultraviolet "Continuum" in Protoplanetary Disk Systems II: CO Fourth Positive Emission and Absorption

We exploit the high sensitivity and moderate spectral resolution of the $HST$-Cosmic Origins Spectrograph to detect far-ultraviolet spectral features of carbon monoxide (CO) present in the inner regions of protoplanetary disks for the first time. We present spectra of the classical T Tauri stars HN Tau, RECX-11, and V4046 Sgr, representative of a range of CO radiative processes. HN Tau shows CO bands in absorption against the accretion continuum. We measure a CO column density and rotational excitation temperature of N(CO) = 2 +/- 1 $\times$ 10$^{17}$ cm$^{-2}$ and T_rot(CO) 500 +/- 200 K for the absorbing gas. We also detect CO A-X band emission in RECX-11 and V4046 Sgr, excited by ultraviolet line photons, predominantly HI LyA. All three objects show emission from CO bands at $\lambda$ $>$ 1560 \AA, which may be excited by a combination of UV photons and collisions with non-thermal electrons. In previous observations these emission processes were not accounted for due to blending with emission from the accretion shock, collisionally excited H$_{2}$, and photo-excited H2; all of which appeared as a "continuum" whose components could not be separated. The CO emission spectrum is strongly dependent upon the shape of the incident stellar LyA emission profile. We find CO parameters in the range: N(CO) 10$^{18-19}$ cm$^{-2}$, T_{rot}(CO) > 300 K for the LyA-pumped emission. We combine these results with recent work on photo- and collisionally-excited H$_{2}$ emission, concluding that the observations of ultraviolet-emitting CO and H2 are consistent with a common spatial origin. We suggest that the CO/H2 ratio in the inner disk is ~1, a transition between the much lower interstellar value and the higher value observed in solar system comets today, a result that will require future observational and theoretical study to confirm.Comment: 12 pages, 7 figures, 3 tables. ApJ - accepte

Movement Patterns for a Critically Endangered Species, the Leatherback Turtle (Dermochelys coriacea), Linked to Foraging Success and Population Status

Foraging success for pelagic vertebrates may be revealed by horizontal and vertical movement patterns. We show markedly different patterns for leatherback turtles in the North Atlantic versus Eastern Pacific, which feed on gelatinous zooplankton that are only occasionally found in high densities. In the Atlantic, travel speed was characterized by two modes, indicative of high foraging success at low speeds (<15 km d−1) and transit at high speeds (20–45 km d−1). Only a single mode was evident in the Pacific, which occurred at speeds of 21 km d−1 indicative of transit. The mean dive depth was more variable in relation to latitude but closer to the mean annual depth of the thermocline and nutricline for North Atlantic than Eastern Pacific turtles. The most parsimonious explanation for these findings is that Eastern Pacific turtles rarely achieve high foraging success. This is the first support for foraging behaviour differences between populations of this critically endangered species and suggests that longer periods searching for prey may be hindering population recovery in the Pacific while aiding population maintenance in the Atlantic

Background Determination for the LUX-ZEPLIN (LZ) Dark Matter Experiment

The LUX-ZEPLIN experiment recently reported limits on WIMP-nucleus interactions from its initial science run, down to $9.2\times10^{-48}$ cm$^2$ for the spin-independent interaction of a 36 GeV/c$^2$ WIMP at 90% confidence level. In this paper, we present a comprehensive analysis of the backgrounds important for this result and for other upcoming physics analyses, including neutrinoless double-beta decay searches and effective field theory interpretations of LUX-ZEPLIN data. We confirm that the in-situ determinations of bulk and fixed radioactive backgrounds are consistent with expectations from the ex-situ assays. The observed background rate after WIMP search criteria were applied was $(6.3\pm0.5)\times10^{-5}$ events/keV$_{ee}$/kg/day in the low-energy region, approximately 60 times lower than the equivalent rate reported by the LUX experiment.Comment: 25 pages, 15 figure

A search for new physics in low-energy electron recoils from the first LZ exposure

The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on a dual-phase xenon time projection chamber. We report searches for new physics appearing through few-keV-scale electron recoils, using the experiment's first exposure of 60 live days and a fiducial mass of 5.5t. The data are found to be consistent with a background-only hypothesis, and limits are set on models for new physics including solar axion electron coupling, solar neutrino magnetic moment and millicharge, and electron couplings to galactic axion-like particles and hidden photons. Similar limits are set on weakly interacting massive particle (WIMP) dark matter producing signals through ionized atomic states from the Migdal effect.Comment: 13 pages, 10 figures. See https://tinyurl.com/LZDataReleaseRun1ER for a data release related to this pape

First Dark Matter Search Results from the LUX-ZEPLIN (LZ) Experiment

The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on a dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility in Lead, South Dakota, USA. This Letter reports results from LZ's first search for Weakly Interacting Massive Particles (WIMPs) with an exposure of 60 live days using a fiducial mass of 5.5 t. A profile-likelihood ratio analysis shows the data to be consistent with a background-only hypothesis, setting new limits on spin-independent WIMP-nucleon, spin-dependent WIMP-neutron, and spin-dependent WIMP-proton cross-sections for WIMP masses above 9 GeV/c$^2$. The most stringent limit is set at 30 GeV/c$^2$, excluding cross sections above 5.9$\times 10^{-48}$ cm$^2$ at the 90\% confidence level.Comment: 9 pages, 6 figures. See https://tinyurl.com/LZDataReleaseRun1 for a data release related to this pape

Type 2 Diabetes Variants Disrupt Function of SLC16A11 through Two Distinct Mechanisms

Type 2 diabetes (T2D) affects Latinos at twice the rate seen in populations of European descent. We recently identified a risk haplotype spanning SLC16A11 that explains ∼20% of the increased T2D prevalence in Mexico. Here, through genetic fine-mapping, we define a set of tightly linked variants likely to contain the causal allele(s). We show that variants on the T2D-associated haplotype have two distinct effects: (1) decreasing SLC16A11 expression in liver and (2) disrupting a key interaction with basigin, thereby reducing cell-surface localization. Both independent mechanisms reduce SLC16A11 function and suggest SLC16A11 is the causal gene at this locus. To gain insight into how SLC16A11 disruption impacts T2D risk, we demonstrate that SLC16A11 is a proton-coupled monocarboxylate transporter and that genetic perturbation of SLC16A11 induces changes in fatty acid and lipid metabolism that are associated with increased T2D risk. Our findings suggest that increasing SLC16A11 function could be therapeutically beneficial for T2D. Video Abstract [Figure presented] Keywords: type 2 diabetes (T2D); genetics; disease mechanism; SLC16A11; MCT11; solute carrier (SLC); monocarboxylates; fatty acid metabolism; lipid metabolism; precision medicin