2,526 research outputs found
Masculinity and Disproportionate Risk of Contact with the Criminal Justice System: Findings from a Select Sample of Low-Income Black Males in New York City
Official statistics document that Black males experience disproportionate contact with the criminal justice system (CJS). Existing theory and research suggest that this contact may be attributed to unique attributes of Black masculine behavior. Utilizing a meta-analysis of Black masculinity studies and content analysis of narratives from a select sample of Black males, ages 19-50, the current study examines the similarities and differences between the construction and performance of normative or traditional masculinity, as measured by Mahalik et als’ CMNI and the attributes of Black masculinity as defined in the literature. A goal of the study was to assess whether Black males’ risk for disproportionate contact with the CJS is attributable to unique ways in which they construct, define, and engage masculine identities; or whether their risk for disproportionate contact with the CJS is substantially attributable to structural responses and impediments to their fulfillment of typical (normative) rather than atypical masculine roles
Account Management in Proof of Stake Ledgers
Blockchain protocols based on Proof-of-Stake (PoS) depend — by nature — on the active participation of stakeholders. If users are offline and abstain from the PoS consensus mechanism, the system’s security is at risk, so it is imperative to explore ways to both maximize the level of participation and minimize the effects of non-participation. One such option is stake representation, such that users can delegate their participation rights and, in the process, form stake pools . The core idea is that stake pool operators always participate on behalf of regular users, while the users retain the ownership of their assets. Our work provides a formal PoS wallet construction that enables delegation and stake pool formation. While investigating the construction of addresses in this setting, we distil and explore address malleability, a security property that captures the ability of an attacker to manipulate the delegation information associated with an address. Our analysis consists of identifying multiple levels of malleability, which are taken into account in our paper’s core result. We then introduce the first ideal functionality of a PoS wallet’s core which captures the PoS wallet’s capabilities and is realized as a secure protocol based on standard cryptographic primitives. Finally, we cover how to use the wallet core in conjunction with a PoS ledger, as well as investigate how delegation and stake pools affect a PoS system’s security
Active Stars in the Spectroscopic Survey of Mid-to-Late M Dwarfs Within 15pc
We present results from the volume-complete spectroscopic survey of
0.1-0.3M M dwarfs within 15pc. This work discusses the active sample
without close binary companions, providing a comprehensive picture of these 123
stars with H emission stronger than -1\unicode{xC5}. Our analysis
includes rotation periods (including 31 new measurements), H
equivalent widths, rotational broadening, inclinations, and radial velocities,
determined using high-resolution, multi-epoch spectroscopic data from the TRES
and CHIRON spectrographs supplemented by photometry from TESS and MEarth. Using
this volume-complete sample, we establish that the majority of active, low-mass
M dwarfs are very rapid rotators: specifically, 744% have rotation periods
shorter than 2 days, while 194% have intermediate rotation periods of 2-20
days, and the remaining 83% have periods longer than 20 days. Among the
latter group, we identify a population of stars with very high H
emission, which we suggest is indicative of dramatic spindown as these stars
transition from the rapidly to slowly rotating modes. We are unable to
determine rotation periods for six stars and suggest that some of the stars
without measured rotation periods may be viewed pole-on, as such stars are
absent from the distribution of inclinations we measure; this lack
notwithstanding, we recover the expected isotropic distribution of spin axes.
Our spectroscopic and photometric data sets also allow us to investigate
activity-induced radial-velocity variability, which we show can be estimated as
the product of rotational broadening and the photometric amplitude of spot
modulation.Comment: Accepted for publication in AJ; 18 pages, 12 figures, 3 table
Four-Round Concurrent Non-Malleable Commitments from One-Way Functions
How many rounds and which assumptions are required for concurrent non-malleable commitments? The above question has puzzled researchers for several years. Pass in [TCC 2013] showed a lower bound of 3 rounds for the case of black-box reductions to falsifiable hardness assumptions with respect to polynomial-time adversaries. On the other side, Goyal [STOC 2011], Lin and Pass [STOC 2011] and Goyal et al. [FOCS 2012] showed that one-way functions (OWFs) are sufficient with a constant number of rounds. More recently Ciampi et al. [CRYPTO 2016] showed a 3-round construction based on subexponentially strong one-way permutations. In this work we show as main result the first 4-round concurrent non-malleable commitment scheme assuming the existence of any one-way function. Our approach builds on a new security notion for argument systems against man-in-the-middle attacks: Simulation-Witness-Independence. We show how to construct a 4-round one-many simulation-witnesses-independent argument system from one-way functions. We then combine this new tool in parallel with a weak form of non-malleable commitments constructed by Goyal et al. in [FOCS 2014] obtaining the main result of our work
HST/WFC3 Light Curve Confirms the Closest Exoplanet to Transit an M Dwarf is Terrestrial
Previous studies of the exoplanet LTT 1445Ac concluded that the light curve
from the Transiting Exoplanet Survey Satellite (TESS) was consistent with both
grazing and non-grazing geometries. As a result, the radius and hence density
of the planet remained unknown. To resolve this ambiguity, we observed the LTT
1445 system for six spacecraft orbits of the Hubble Space Telescope (HST) using
WFC3/UVIS imaging in spatial scan mode, including one partial transit of LTT
1445Ac. This imaging produces resolved light curves of each of the three stars
in the LTT 1445 system. We confirm that the planet transits LTT 1445A and that
LTT 1445C is the source of the rotational modulation seen in the TESS light
curve, and we refine the estimate of the dilution factor for the TESS data. We
perform a joint fit to the TESS and HST observations, finding that the transit
of LTT 1445Ac is not grazing with 97% confidence. We measure a planetary radius
of 1.10 R. Combined with previous radial velocity
observations, our analysis yields a planetary mass of M
and a planetary density of 5.6 g cm. LTT 1445Ac is an
Earth analog with respect to its mass and radius, albeit with a higher
instellation, and is therefore an exciting target for future atmospheric
studies.Comment: Submitted to AJ. 9 pages, 7 figures, 3 table
Mid-to-Late M Dwarfs Lack Jupiter Analogs
Cold Jovian planets play an important role in sculpting the dynamical
environment in which inner terrestrial planets form. The core accretion model
predicts that giant planets cannot form around low-mass M dwarfs, although this
idea has been challenged by recent planet discoveries. Here, we investigate the
occurrence rate of giant planets around low-mass (0.1-0.3M) M dwarfs.
We monitor a volume-complete, inactive sample of 200 such stars located within
15 parsecs, collecting four high-resolution spectra of each M dwarf over six
years and performing intensive follow-up monitoring of two candidate
radial-velocity variables. We use TRES on the 1.5 m telescope at the Fred
Lawrence Whipple Observatory and CHIRON on the Cerro Tololo Inter-American
Observatory 1.5 m telescope for our primary campaign, and MAROON-X on Gemini
North for high-precision follow-up. We place a 95%-confidence upper limit of
1.5% (68%-confidence limit of 0.57%) on the occurrence of sin1M giant planets out to the water snow line and provide additional
constraints on the giant planet population as a function of sin
and period. Beyond the snow line ( K K), we place
95%-confidence upper limits of 1.5%, 1.7%, and 4.4% (68%-confidence limits of
0.58%, 0.66%, and 1.7%) for 3MsinM,
0.8MsinM, and 0.3MsinM giant planets; i.e., Jupiter analogs are rare around
low-mass M dwarfs. In contrast, surveys of Sun-like stars have found that their
giant planets are most common at these Jupiter-like instellations.Comment: Accepted for publication in AJ; 19 pages, 5 figures, 2 table
(No) Quantum space-time tradeoff for USTCON
Undirected st-connectivity is important both for its applications in network problems, and for its theoretical connections with logspace complexity. Classically, a long line of work led to a time-space tradeoff of T = Oe(n2/S) for any S such that S = Ω(log(n)) and S = O(n2/m). Surprisingly, we show that quantumly there is no nontrivial time-space tradeoff: there is a quantum algorithm that achieves both optimal time Oe(n) and space O(log(n)) simultaneously. This improves on previous results, which required either O(log(n)) space and Oe(n1.5) time, or Oe(n) space and time. To complement this, we show that there is a nontrivial time-space tradeoff when given a lower bound on the spectral gap of a corresponding random walk
Implementation of routine outcome measurement in child and adolescent mental health services in the United Kingdom: a critical perspective
The aim of this commentary is to provide an overview of clinical outcome measures that are currently recommended for use in UK Child and Adolescent Mental Health Services (CAMHS), focusing on measures that are applicable across a wide range of conditions with established validity and reliability, or innovative in their design. We also provide an overview of the barriers and drivers to the use of Routine Outcome Measurement (ROM) in clinical practice
Incidence, healthcare-seeking behaviours, antibiotic use and natural history of common infection syndromes in England: results from the Bug Watch community cohort study
Background: Better information on the typical course and management of acute common infections in the
community could inform antibiotic stewardship campaigns. We aimed to investigate the incidence, management,
and natural history of a range of infection syndromes (respiratory, gastrointestinal, mouth/dental, skin/soft tissue,
urinary tract, and eye).
Methods: Bug Watch was an online prospective community cohort study of the general population in England
(2018–2019) with weekly symptom reporting for 6 months. We combined symptom reports into infection
syndromes, calculated incidence rates, described the proportion leading to healthcare-seeking behaviours and
antibiotic use, and estimated duration and severity.
Results: The cohort comprised 873 individuals with 23,111 person-weeks follow-up. The mean age was 54 years
and 528 (60%) were female. We identified 1422 infection syndromes, comprising 40,590 symptom reports. The
incidence of respiratory tract infection syndromes was two per person year; for all other categories it was less than
one. 194/1422 (14%) syndromes led to GP (or dentist) consultation and 136/1422 (10%) to antibiotic use. Symptoms
usually resolved within a week and the third day was the most severe.
Conclusions: Most people reported managing their symptoms without medical consultation. Interventions
encouraging safe self-management across a range of acute infection syndromes could decrease pressure on
primary healthcare services and support targets for reducing antibiotic prescribing
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