140 research outputs found
A Summer Camp in Engineering Physics for Incoming Freshman to Improve Retention and Student Success
Summer camps have proven to be a valuable tool to attract and recruit students interested in pursuing a career in the STEM field. They have been also used to spark their curiosity in areas like mathematics. However, these camps do not help with issues that appear after the student has been admitted at the university. It is well known that many students are shocked when they transition from high-school to college. Many of them do not know how to handle their academic freedom; they start without any friends, and they do not know the campus and the resources available. By realizing this situation a 1-week resident summer camp for incoming freshman has been created at . The goal of this is camp is to help them with their transition from high-school to college. During the summer camp, they review concepts related to Math and Science, they are introduced to the campus and resources available, and they meet other students who are also interested in pursuing a career in the STEM field. The students stay at the dormitories located in campus; they eat in the cafeteria, and they collaborate with the professors in classroom and laboratory settings
Aligning AI With Shared Human Values
We show how to assess a language model's knowledge of basic concepts of
morality. We introduce the ETHICS dataset, a new benchmark that spans concepts
in justice, well-being, duties, virtues, and commonsense morality. Models
predict widespread moral judgments about diverse text scenarios. This requires
connecting physical and social world knowledge to value judgements, a
capability that may enable us to steer chatbot outputs or eventually regularize
open-ended reinforcement learning agents. With the ETHICS dataset, we find that
current language models have a promising but incomplete ability to predict
basic human ethical judgements. Our work shows that progress can be made on
machine ethics today, and it provides a steppingstone toward AI that is aligned
with human values.Comment: ICLR 2021; the ETHICS dataset is available at
https://github.com/hendrycks/ethics
X-ray/UVOIR Frequency-resolved Time Lag Analysis of Mrk 335 Reveals Accretion Disk Reprocessing
UV and optical continuum reverberation mapping is powerful for probing the
accretion disk and inner broad-line region. However, recent reverberation
mapping campaigns in the X-ray, UV, and optical have found lags consistently
longer than those expected from the standard disk reprocessing picture. The
largest discrepancy to-date was recently reported in Mrk 335, where UV/optical
lags are up to 12 times longer than expected. Here, we perform a
frequency-resolved time lag analysis of Mrk 335, using Gaussian processes to
account for irregular sampling. For the first time, we compare the Fourier
frequency-resolved lags directly to those computed using the popular
Interpolated Cross-Correlation Function (ICCF) method applied to both the
original and detrended light curves. We show that the anticipated disk
reverberation lags are recovered by the Fourier lags when zeroing in on the
short-timescale variability. This suggests that a separate variability
component is present on long timescales. If this separate component is modeled
as reverberation from another region beyond the accretion disk, we constrain a
size-scale of roughly 15 light-days from the central black hole. This is
consistent with the size of the broad line region inferred from H
reverberation lags. We also find tentative evidence for a soft X-ray lag, which
we propose may be due to light travel time delays between the hard X-ray corona
and distant photoionized gas that dominates the soft X-ray spectrum below 2
keV.Comment: Accepted for publication in ApJ, 8 figure
Protecting browsers from dns rebinding attacks
DNS rebinding attacks subvert the same-origin policy of browsers, converting them into open network proxies. Using DNS rebinding, an attacker can circumvent organizational and personal firewalls, send spam email, and defraud pay-per-click advertisers. We evaluate the cost effectiveness of mounting DNS rebinding attacks, finding that an attacker requires less than $100 to hijack 100,000 IP addresses. We analyze defenses to DNS rebinding attacks, including improvements to the classic “DNS pinning, ” and recommend changes to browser plug-ins, firewalls, and Web servers. Our defenses have been adopted by plug-in vendors and by a number of open-source firewall implementations
Recommended from our members
Repurposing the GNAT Fold in the Initiation of Polyketide Biosynthesis.
Natural product biosynthetic pathways are replete with enzymes repurposed for new catalytic functions. In some modular polyketide synthase (PKS)Â pathways, a GCN5-related N-acetyltransferase (GNAT)-like enzyme with an additional decarboxylation function initiates biosynthesis. Here, we probe two PKS GNAT-like domains for the dual activities of S-acyl transfer from coenzyme A (CoA) to an acyl carrier protein (ACP) and decarboxylation. The GphF and CurA GNAT-like domains selectively decarboxylate substrates that yield the anticipated pathway starter units. The GphF enzyme lacks detectable acyl transfer activity, and a crystal structure with an isobutyryl-CoA product analog reveals a partially occluded acyltransfer acceptor site. Further analysis indicates that the CurA GNAT-like domain also catalyzes only decarboxylation, and the initial acyl transfer is catalyzed by an unidentified enzyme. Thus, PKS GNAT-like domains are re-classified as GNAT-like decarboxylases. Two other decarboxylases, malonyl-CoA decarboxylase and EryM, reside on distant nodes of the superfamily, illustrating the adaptability of the GNAT fold
Characterization of a Novel Influenza Virus in Cattle and Swine: Proposal for a New Genus in the Orthomyxoviridae Family
We have recently reported the isolation of a novel virus, provisionally designated C/swine/Oklahoma/1334/2011 (C/OK), with 50% overall homology to human influenza C viruses (ICV), from a pig in Oklahoma. Deep RNA sequencing of C/OK virus found a matrix 1 (M1) protein expression strategy that differed from that of ICV. The novelty of C/OK virus prompted us to investigate whether C/OK virus could exist in a nonswine species. Significantly, we found that C/OK virus was widespread in U.S. bovine herds, as demonstrated by reverse transcription (RT)-PCR and serological assays. Genome sequencing of three bovine viruses isolated from two herds in different states further confirmed these findings. To determine whether swine/bovine C/OK viruses can undergo reassortment with human ICV, and to clarify the taxonomic status of C/OK, in vitro reassortment and serological typing by agar gel immunodiffusion (AGID) were conducted. In vitro reassortment using two human ICV and two swine and bovine C/OK viruses demonstrated that human ICV and C/OK viruses were unable to reassort and produce viable progeny. Antigenically, no cross-recognition of detergent split virions was observed in AGID between human and nonhuman viruses by using polyclonal antibodies that were reactive to cognate antigens. Taken together, these results demonstrate that C/OK virus is genetically and antigenically distinct from ICV. The classification of the new virus in a separate genus of the Orthomyxoviridae family is proposed. The finding of C/OK virus in swine and bovine indicates that this new virus may spread and establish infection in other mammals, including humans
UV/Optical disk reverberation lags despite a faint X-ray corona in the AGN Mrk 335
We present the first results from a 100-day Swift, NICER and ground-based
X-ray/UV/optical reverberation mapping campaign of the Narrow-Line Seyfert 1
Mrk 335, when it was in an unprecedented low X-ray flux state. Despite dramatic
suppression of the X-ray variability, we still observe UV/optical lags as
expected from disk reverberation. Moreover, the UV/optical lags are consistent
with archival observations when the X-ray luminosity was >10 times higher.
Interestingly, both low- and high-flux states reveal UV/optical lags that are
6-11 times longer than expected from a thin disk. These long lags are often
interpreted as due to contamination from the broad line region, however the u
band excess lag (containing the Balmer jump from the diffuse continuum) is less
prevalent than in other AGN. The Swift campaign showed a low X-ray-to-optical
correlation (similar to previous campaigns), but NICER and ground-based
monitoring continued for another two weeks, during which the optical rose to
the highest level of the campaign, followed ~10 days later by a sharp rise in
X-rays. While the low X-ray countrate and relatively large systematic
uncertainties in the NICER background make this measurement challenging, if the
optical does lead X-rays in this flare, this indicates a departure from the
zeroth-order reprocessing picture. If the optical flare is due to an increase
in mass accretion rate, this occurs on much shorter than the viscous timescale.
Alternatively, the optical could be responding to an intrinsic rise in X-rays
that is initially hidden from our line-of-sight.Comment: Accepted for publication in the Astrophysical Journal. 15 pages, 8
figures, 3 table
Making Place: Transit-Oriented Development for Largo, MD
Final project for ARCH700: Urban Design Studio VII(Fall 2019). University of Maryland, College Park.Largo, MD is a city of 12,000 people at the intersection of the
Beltway
and the Metropolitan DC Blue Line. It is currently
being planned as the future center of the Prince George’s
County Government and the home of the new University of
Maryland Capital Region Medical Center. The overall site
has exceptional access to transit and offers myriad ways to
travel but in itself lacks appeal as a “place”. It has developed
as a suburban “Edge City” on the outskirts of the District of
Columbia, a simple automobile-oriented pit stop in-between
the jobs and sights of the national capital and the dwellings of
those who work and visit.
As part of the Partnership for Action Learning in Sustainability
(PALS), The Prince George’s County Department of
Planning approached the University of Maryland’s Program
in Architecture with a request to investigate the Largo metro
site as a more fully realized transit-oriented development
hosting a full mix of uses, from the new seat of the county’s
government to the new hospital and residential development.
The studio focused on questions of place, development, and
identity while grappling with the fragmented pattern of development
that currently defines Largo. The studio proposals
demonstrate the potential of a new identity for the area using
transit oriented design principles, restoration of the natural
environment, and making Largo a “green jewel of a town” at
the heart of Prince George’s County.Prince George's Count
The Impact of Earnings on the Pricing of Credit Default Swaps
This study evaluates the impact of earnings on credit risk in the Credit Default Swap (CDS) market using levels, changes, and event study analyses. We find that earnings (cash flows, accruals) of reference firms are negatively and significantly correlated with the level of CDS premia, consistent with earnings (cash flows, accruals) conveying information about default risk. Based on the changes analysis, a 1 percent increase in ROA decreases CDS rates significantly by about 5 percent. We also find that (1) CDS premia are more highly correlated with below-median earnings than with above-median earnings and (2) CDS premia are more highly correlated with earnings of low-rated firms than with earnings of high-rated firms. Evidence indicates further that short-window earnings surprises are negatively and significantly correlated with CDS premia changes in the three-day window surrounding the preliminary earnings announcement, although the impact is concentrated in the shorter maturities
- …