An Untriggered Search for Optical Bursts

We present an untriggered search for optical bursts with the ROTSE-I telephoto array. Observations were taken which monitor an effective 256 square degree field continuously over 125 hours to m_{ROTSE}=15.7. The uniquely large field, moderate limiting magnitude and fast cadence of $\sim$10 minutes permits transient searches in a new region of sensitivity. Our search reveals no candidate events. To quantify this result, we simulate potential optical bursts with peak magnitude, m_{p}, at t=10 s, which fade as f=(\frac{t}{t_{0}}) ^{\alpha_{t}}, where \alpha_t < 0. Simple estimates based on observational evidence indicate that a search of this sensitivity begins to probe the possible region occupied by GRB orphan afterglows. Our observing protocol and image sensitivity result in a broad region of high detection efficiency for light curves to the bright and slowly varying side of a boundary running from [\alpha_{t},m_{p}]=[-2.0,6.0] to [-0.3,13.2]. Within this region, the integrated rate of brief optical bursts is less than 1.1\times 10^{-8} {\rm s}^{-1} {\rm deg}^{-2}. At $\sim$22 times the observed GRB rate from BATSE, this suggests a limit on \frac{\theta_{opt}}{\theta_{\gamma}}\lesssim 5 where \theta_{opt} and \theta_{\gamma} are the optical and gamma-ray collimation angles, respectively. Several effects might explain the absence of optical bursts, and a search of the kind described here but more sensitive by about 4 magnitudes should offer a more definitive probe.Comment: 8 pages, 6 figures, 1 tabl

A Search for Early Optical Emission from Short and Long Duration Gamma-ray Bursts

Gamma-ray bursts of short duration may harbor vital clues to the range of phenomena producing bursts. However, recent progress from the observation of optical counterparts has not benefitted the study of short bursts. We have searched for early optical emission from six gamma-ray bursts using the ROTSE-I telephoto array. Three of these events were of short duration, including GRB 980527 which is among the brightest short bursts yet observed. The data consist of unfiltered CCD optical images taken in response to BATSE triggers delivered via the GCN. For the first time, we have analyzed the entire 16 degree by 16 degree field covered for five of these bursts. In addition, we discuss a search for the optical counterpart to GRB 000201, a well-localized long burst. Single image sensitivities range from 13th to 14th magnitude around 10 s after the initial burst detection, and 14 - 15.8 one hour later. No new optical counterparts were discovered in this analysis suggesting short burst optical and gamma-ray fluxes are uncorrelated.Comment: 8 pages, 2 figures, subm. to ApJ Let

Prompt Optical Observations of Gamma-ray Bursts

The Robotic Optical Transient Search Experiment (ROTSE) seeks to measure simultaneous and early afterglow optical emission from gamma-ray bursts (GRBs). A search for optical counterparts to six GRBs with localization errors of 1 square degree or better produced no detections. The earliest limiting sensitivity is m(ROTSE) > 13.1 at 10.85 seconds (5 second exposure) after the gamma-ray rise, and the best limit is m(ROTSE) > 16.0 at 62 minutes (897 second exposure). These are the most stringent limits obtained for GRB optical counterpart brightness in the first hour after the burst. Consideration of the gamma-ray fluence and peak flux for these bursts and for GRB990123 indicates that there is not a strong positive correlation between optical flux and gamma-ray emission.Comment: 4 pages, 3 figures, submitted to ApJ Letter

Transnational agricultural land acquisitions threaten biodiversity in the Global South

Agricultural large-scale land acquisitions have been linked with enhanced deforestation and land use change. Yet the extent to which transnational agricultural large-scale land acquisitions (TALSLAs) contribute to—or merely correlate with—deforestation, and the expected biodiversity impacts of the intended land use changes across ecosystems, remains unclear. We examine 178 georeferenced TALSLA locations in 40 countries to address this gap. While forest cover within TALSLAs decreased by 17% between 2000 and 2018 and became more fragmented, the spatio-temporal patterns of deforestation varied substantially across regions. While deforestation rates within initially forested TALSLAs were 1.5 (Asia) to 2 times (Africa) higher than immediately surrounding areas, we detected no such difference in Europe and Latin America. Our findings suggest that, whereas TALSLAs may have accelerated forest loss in Asia, a different mechanism might emerge in Africa where TALSLAs target areas already experiencing elevated deforestation. Regarding biodiversity (here focused on vertebrate species), we find that nearly all (91%) studied deals will likely experience substantial losses in relative species richness (−14.1% on average within each deal)—with mixed outcomes for relative abundance—due to the intended land use transitions. We also find that 39% of TALSLAs fall at least partially within biodiversity hotspots, placing these areas at heightened risk of biodiversity loss. Taken together, these findings suggest distinct regional differences in the nature of the association between TALSLAs and forest loss and provide new evidence of TALSLAs as an emerging threat to biodiversity in the Global South

The Vascular Impairment of Cognition Classification Consensus Study

H. Jokinen työryhmän jäsenenä.Introduction: Numerous diagnostic criteria have tried to tackle the variability in clinical manifestations and problematic diagnosis of vascular cognitive impairment (VCI) but none have been universally accepted. These criteria have not been readily comparable, impacting on clinical diagnosis rates and in turn prevalence estimates, research, and treatment. Methods: The Vascular Impairment of Cognition Classification Consensus Study (VICCCS) involved participants (81% academic researchers) from 27 countries in an online Delphi consensus study. Participants reviewed previously proposed concepts to develop new guidelines. Results: VICCCS had a mean of 122 (98-153) respondents across the study and a 67% threshold to represent consensus. VICCCS redefined VCI including classification of mild and major forms of VCI and subtypes. It proposes new standardized VCI-associated terminology and future research priorities to address gaps in current knowledge. Discussion: VICCCS proposes a consensus-based updated conceptualization of VCI intended to facilitate standardization in research. (C) 2016 the Alzheimer's Association. Published by Elsevier Inc. All rights reserved.Peer reviewe

The ROTSE detection of early optical light from GRB 990123

An overview is given of the Robotic Optical Transient Search Experiment, a ground-based observational astronomy project intended to detect visible radiation from gamma-ray bursts. The major result of the project was the detection of an early bright optical transient from a GRB. (AIP) © 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87569/2/82_1.pd

Analysis of common and rare VPS13C variants in late-onset Parkinson disease

Objective We aimed to study the role of coding VPS13C variants in a large cohort of patients with lateonset Parkinson disease (PD) (LOPD). Methods VPS13C and its untranslated regions were sequenced using targeted next-generation sequencing in 1,567 patients with PD and 1,667 controls from 3 cohorts. Association tests of rare potential homozygous and compound heterozygous variants and burden tests for rare heterozygous variants were performed. Common variants were analyzed using logistic regression adjusted for age and sex in each of the cohorts, followed by a meta-analysis. Results No biallelic carriers of rare VPS13C variants were found among patients, and 2 carriers of compound heterozygous variants were found in 2 controls. There was no statistically significant burden of rare (minor allele frequency [MAF] <1%) or very rare (MAF <0.1%) coding VPS13C variants in PD. A VPS13C haplotype including the p.R153H-p.I398I-p.I1132V-p.Q2376Q variants was nominally associated with a reduced risk for PD (meta-analysis of the tagging SNP p.I1132V [odds ratio = 0.48, 95% confidence interval = 0.28–0.82, p = 0.0052]). This haplotype was not in linkage disequilibrium with the known genome-wide association study top hit. Conclusions Our results do not support a role for rare heterozygous or biallelic VPS13C variants in LOPD. Additional genetic replication and functional studies are needed to examine the role of the haplotype identified here associated with reduced risk for PD

Progress toward standardized diagnosis of vascular cognitive impairment: Guidelines from the Vascular Impairment of Cognition Classification Consensus Study

INTRODUCTION: Progress in understanding and management of vascular cognitive impairment (VCI) has been hampered by lack of consensus on diagnosis, reflecting the use of multiple different assessment protocols. A large multinational group of clinicians and researchers participated in a two-phase Vascular Impairment of Cognition Classification Consensus Study (VICCCS) to agree on principles (VICCCS-1) and protocols (VICCCS-2) for diagnosis of VCI. We present VICCCS-2. METHODS: We used VICCCS-1 principles and published diagnostic guidelines as points of reference for an online Delphi survey aimed at achieving consensus on clinical diagnosis of VCI. RESULTS: Six survey rounds comprising 65-79 participants agreed guidelines for diagnosis of VICCCS-revised mild and major forms of VCI and endorsed the National Institute of Neurological Disorders-Canadian Stroke Network neuropsychological assessment protocols and recommendations for imaging. DISCUSSION: The VICCCS-2 suggests standardized use of the National Institute of Neurological Disorders-Canadian Stroke Network recommendations on neuropsychological and imaging assessment for diagnosis of VCI so as to promote research collaboration

New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele