18,730 research outputs found
Leveraging bluetooth as a second factor in two-factor authentication
Passwords have been the dominant single-factor authentication method for decades but are no longer sufficient to validate a user\u27s identity. The simplistic nature of passwords perpetuate their existence and makes them an easy attack vector. However, Two-Factor Authentication (2FA) augments passwords and adds a layer of security. Although 2FA has the potential to increase security, traditional second factors require user interaction at every login attempt, which may contribute to slow adaptation. Traditional second factors drastically alter the user authentication experience and typically require the user to navigate away from the login screen. Therefore, we present a new second-factor method that leverages Bluetooth technology called Ambient-Discovery. Our protocol is designed to provide security assurances comparable to or greater than the traditional second factors while keeping the user experience the same as password-based authentication. There is no user interaction, as the second factor restricts communication between a mobile application and a computer browser. Therefore, Ambient-Discovery provides an additional layer of security while limiting user interaction
Leveraging bluetooth as a second factor in two-factor authentication
Passwords have been the dominant single-factor authentication method for decades but are no longer sufficient to validate a user\u27s identity. The simplistic nature of passwords perpetuate their existence and makes them an easy attack vector. However, Two-Factor Authentication (2FA) augments passwords and adds a layer of security. Although 2FA has the potential to increase security, traditional second factors require user interaction at every login attempt, which may contribute to slow adaptation. Traditional second factors drastically alter the user authentication experience and typically require the user to navigate away from the login screen. Therefore, we present a new second-factor method that leverages Bluetooth technology called Ambient-Discovery. Our protocol is designed to provide security assurances comparable to or greater than the traditional second factors while keeping the user experience the same as password-based authentication. There is no user interaction, as the second factor restricts communication between a mobile application and a computer browser. Therefore, Ambient-Discovery provides an additional layer of security while limiting user interaction
GRB optical afterglow and redshift selection effects: The learning curve effect at work
We show how the observed gamma ray burst (GRB) optical afterglow (OA) and
redshift distributions are changing in time from selection effects. For a
subset of {\it Swift} triggered long duration bursts, we show that the mean
time taken to acquire spectroscopic redshifts for a GRB OA has evolved to
shorter times. We identify a strong correlation between the mean time taken to
acquire a spectroscopic redshift and the measured redshift. This correlation
reveals that shorter response times favour smaller redshift bursts. This is
compelling evidence for a selection effect that biases longer response times
with relatively brighter high redshift bursts. Conversely, for shorter response
times, optically fainter bursts that are relatively closer are bright enough
for spectroscopic redshifts to be acquired. This selection effect could explain
why the average redshift, measured in 2005, has evolved to
, by mid 2008. Understanding these selection effects provides an
important tool for separating the contributions of intrinsically faint bursts,
those obscured by host galaxy dust and bursts not seen in the optical because
their OAs are observed at late times. The study highlights the importance of
rapid response telescopes capable of spectroscopy, and identifies a new
redshift selection effect that has not been considered previously, namely the
response time to measure the redshift.Comment: 5 pages, 4 figures, MNRAS Letter (accepted
Damped Lyman Alpha Systems at z<1.65: The Expanded SDSS HST Sample
We present results of our HST Cycle 11 Survey for low-redshift (z<1.65) DLAs
in the UV spectra of quasars selected from the SDSS Early Data Release. These
quasars have strong intervening MgII-FeII systems which are known signatures of
high column density neutral gas. In total, UV observations of Ly-alpha
absorption in 197 MgII systems with z<1.65 and rest equivalent width (REW)
W2796 \ge 0.3A have now been obtained. The main results are: (1) 36(+/- 6)% of
systems with W2796 \ge 0.5 A and FeII W2600 \ge 0.5 A are DLAs. This increases
to 42(+/- 7)% for systems with W2796/W2600 0.1 A. (2) The
mean N(HI) of MgII systems with 0.3 A \le W2796 < 0.6 A is a factor of ~36
lower than that of systems with W2796 \ge 0.6 A. (3) The DLA incidence per unit
redshift is consistent with no evolution for z <~ 2 (Omega_L=0.7, Omega_M =
0.3), but exhibits significant evolution for z >~ 2. (4) Omega_{DLA} is
constant for 0.5<z<5.0 to within the uncertainties. This is larger than
Omega_{gas}(z=0) by a factor of ~2. (5) The slope of the N(HI) distribution
does not change significantly with redshift. However, the low redshift
distribution is marginally flatter due to the higher fraction of high N(HI)
systems in our sample. (6) Finally, using the precision of MgII survey
statistics, we find that there may be evidence of a decreasing Omega_{DLA} from
z=0.5 to z=0. We reiterate the conclusion of Hopkins, Rao, & Turnshek that very
high columns of neutral gas might be missed by DLA surveys because of their
very small cross sections, and therefore, that Omega_{DLA} might not include
the bulk of the neutral gas mass in the Universe. (Abridged)Comment: Accepted for publication in ApJ. 22 pages, 22 figure
A temperate former West Antarctic ice sheet suggested by an extensive zone of bed channels
Several recent studies predict that the West Antarctic Ice Sheet will become increasingly unstable under warmer conditions. Insights on such change can be assisted through investigations of the subglacial landscape, which contains imprints of former ice-sheet behavior. Here, we present radio-echo sounding data and satellite imagery revealing a series of ancient large sub-parallel subglacial bed channels preserved in the region between the Möller and Foundation Ice Streams, West Antarctica. We suggest that these newly recognized channels were formed by significant meltwater routed along the icesheet bed. The volume of water required is likely substantial and can most easily be explained by water generated at the ice surface. The Greenland Ice Sheet today exemplifies how significant seasonal surface melt can be transferred to the bed via englacial routing. For West Antarctica, the Pliocene (2.6â5.3 Ma) represents the most recent sustained period when temperatures could have been high enough to generate surface melt comparable to that of present-day Greenland. We propose, therefore, that a temperate ice sheet covered this location during Pliocene warm periods
CDAO-Store: Ontology-driven Data Integration for Phylogenetic Analysis
<p>Abstract</p> <p>Background</p> <p>The <it>Comparative Data Analysis Ontology (CDAO) </it>is an ontology developed, as part of the EvoInfo and EvoIO groups supported by the National Evolutionary Synthesis Center, to provide semantic descriptions of data and transformations commonly found in the domain of phylogenetic analysis. The core concepts of the ontology enable the description of phylogenetic trees and associated character data matrices.</p> <p>Results</p> <p>Using CDAO as the semantic back-end, we developed a triple-store, named <it>CDAO</it>-<it>Store</it>. CDAO-Store is a RDF-based store of phylogenetic data, including a complete import of TreeBASE. CDAO-Store provides a programmatic interface, in the form of web services, and a web-based front-end, to perform both user-defined as well as domain-specific queries; domain-specific queries include search for nearest common ancestors, minimum spanning clades, filter multiple trees in the store by size, author, taxa, tree identifier, algorithm or method. In addition, CDAO-Store provides a visualization front-end, called <it>CDAO</it>-<it>Explorer</it>, which can be used to view both character data matrices and trees extracted from the CDAO-Store. CDAO-Store provides import capabilities, enabling the addition of new data to the triple-store; files in PHYLIP, MEGA, <monospace>nexml</monospace>, and NEXUS formats can be imported and their CDAO representations added to the triple-store.</p> <p>Conclusions</p> <p>CDAO-Store is made up of a versatile and integrated set of tools to support phylogenetic analysis. To the best of our knowledge, CDAO-Store is the first semantically-aware repository of phylogenetic data with domain-specific querying capabilities. The portal to CDAO-Store is available at <url>http://www.cs.nmsu.edu/~cdaostore</url>.</p
Fingerprint of Climate Change on Southern Ocean Carbon Storage
The Southern Ocean plays a critical role in the uptake, transport, and storage of carbon by the global oceans. It is the ocean's largest sink of CO2, yet it is also among the regions with the lowest storage of anthropogenic carbon. This behavior results from a unique combination of high winds driving the upwelling of deep waters and the subduction and northward transport of surface carbon. Here we isolate the direct effect of increasing anthropogenic CO2 in the atmosphere from the indirect effect of climate variability and climate change on the reorganization of carbon in the Southern Ocean interior using a combination of modeling and observations. We show that the effect of climate variability and climate change on the storage of carbon in the Southern Ocean is nearly as large as the effect of anthropogenic CO2 during the period 1998â2018 compared with the climatology around the year 1995. We identify a distinct climate fingerprint in dissolved inorganic carbon (DIC), with elevated DIC concentration in the ocean at 300â600 m that reinforces the anthropogenic CO2 signal, and reduced DIC concentration in the ocean around 2,000 m that offsets the anthropogenic CO2 signal. The fingerprint is strongest at lower latitudes (30°â55°S). This fingerprint could serve to monitor the highly uncertain evolution of carbon within this critical ocean basin, and better identify its drivers.publishedVersio
A far UV study of interstellar gas towards HD34078: high excitation H2 and small scale structure - Based on observations performed by the FUSE mission and at the CFHT telescope
To investigate the presence of small scale structure in the spatial
distribution of H2 molecules we have undertaken repeated FUSE UV observations
of the runaway O9.5V star, HD34078. In this paper we present five spectra
obtained between January 2000 and October 2002. These observations reveal an
unexpectedly large amount of highly excited H2. Column densities for H2 levels
from (v = 0, J = 0) up to (v = 0, J = 11) and for several v = 1 and v = 2
levels are determined. These results are interpreted in the frame of a model
involving essentially two components: i) a foreground cloud (unaffected by
HD34078) responsible for the H2 (J = 0, 1), CI, CH, CH+ and CO absorptions; ii)
a dense layer of gas (n = 10E4 cm-3) close to the O star and strongly
illuminated by its UV flux which accounts for the presence of highly excited
H2. Our model successfully reproduces the H2 excitation, the CI fine-structure
level populations as well as the CH, CH+ and CO column densities. We also
examine the time variability of H2 absorption lines tracing each of these two
components. From the stability of the J = 0, 1 and 2 damped H2 profiles we
infer a 3 sigma upper limit on column density variations Delta(N(H2))/N(H2) of
5% over scales ranging from 5 to 50 AU. This result clearly rules out any
pronounced ubiquitous small scale "density" structure of the kind apparently
seen in HI. The lines from highly excited gas are also quite stable (equivalent
to Delta(N)/N <= 30%) indicating i) that the ambient gas through which HD34078
is moving is relatively uniform and ii) that the gas flow along the shocked
layer is not subject to marked instabilitie
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