13,219 research outputs found
Challenges to smartphone applications for melanoma detection
This commentary addresses the emerging market for health-related smartphone applications. Specific to dermatology, there has been a significant increase not only in applications that promote skin cancer awareness and education but also in those meant for detection. With evidence showing that 365 dermatology-related applications were available in 2014--up from 230 in 2012--and that 1 in 5 patients under the age of 50 have used a smartphone to help diagnose a skin problem, there is clearly a large subset of patients participating in this growing trend. Therefore, we are obligated to take a closer look into this phenomenon. Studies have shown that applications are inferior to in-person consultations with one study showing that 3 out of 4 applications incorrectly classified 30% or more melanomas as low-risk lesions. Although the FDA gained regulatory oversight over mobile health applications in 2012 and recently released their statement in 2015, their reach only extends to cover a selected portion of these applications, leaving many unregulated as they continue to be marketed toward our patients. Dermatologists should be updated on our current situation in order to properly counsel patients on the risks and benefits of these applications and whether they are acceptable for use. © 2016 by the article author(s)
Semileptonic decays in the limit of a heavy daughter quark
The rate of the semileptonic decay b to c l v is calculated with order
alphas^2 accuracy, as an expansion around the limit of equal masses of the b
and c quarks. Recent results obtained around the limit of the c-quark much
lighter than b are confirmed. Details of the new expansion method are
described.Comment: 7 pages, 5 figure
Semi-Leptonic b-decay at Intermediate Recoil
We compute the O(\alpha_s^2) corrections to the differential rate of the
semileptonic decay b -> clv at the "intermediate recoil" point, where the
c-quark mass and the invariant mass of the leptons are equal. The calculation
is based on an expansion around two opposite limits of the quark masses
m_{b,c}: m_c ~ m_b and m_c << m_b. The former case was previously studied; we
correct and extend that result. The latter case is new. The smooth matching of
both expansions provides a check of both. We clarify the discrepancy between
the recent determinations of the full NNLO QCD correction to the semileptonic b
-> c rate, and its earlier estimate.Comment: 9 pages, 6 figures, Replaced figures, small format and typo
corrections, added appendix and reference
Great Bay Nitrogen Non-Point Source Study
The Great Bay Estuary is 21 square miles of tidal waters located in southeastern New Hampshire. It is one of 28 “estuaries of national significance” established under the Environmental Protection Agency’s National Estuary Program. The estuary is experiencing the signs of eutrophication, specifically, low dissolved oxygen, macroalgae blooms, and declining eelgrass habitat (DES, 2012).
Sixty-eight percent of the nitrogen that ends up in the Great Bay Estuary originates from sources spread across the watershed; the remainder derives from direct discharges of municipal wastewater treatment facilities (DES, 2010; PREP, 2013). In this report, these sources of nitrogen are called non-point sources and consist of atmospheric deposition, fertilizers, human waste disposed into septic systems, and animal waste. The purpose of this study is to determine how much nitrogen each non-point source type contributes to the estuary. The nitrogen loads from municipal wastewater treatment facilities have been reported elsewhere (DES, 2010; PREP, 2012; PREP, 2013) and, therefore, are not included in this study except to provide context.
The intended use of this study is for planning purposes, and is not meant for regulatory allocations or specific reduction requirements. The results of the model may be useful for towns or watershed groups for prioritizing nitrogen reduction efforts or as a starting point for more detailed studies of non-point sources. However, more detailed inventories of non-point sources will be needed to track the effects of nitrogen reduction efforts in smaller areas. In addition, the model makes no conclusions about the benefits of nitrogen reductions to receiving waters or overall estuarine health
Selling a Single Item with Negative Externalities
We consider the problem of regulating products with negative externalities to
a third party that is neither the buyer nor the seller, but where both the
buyer and seller can take steps to mitigate the externality. The motivating
example to have in mind is the sale of Internet-of-Things (IoT) devices, many
of which have historically been compromised for DDoS attacks that disrupted
Internet-wide services such as Twitter. Neither the buyer (i.e., consumers) nor
seller (i.e., IoT manufacturers) was known to suffer from the attack, but both
have the power to expend effort to secure their devices. We consider a
regulator who regulates payments (via fines if the device is compromised, or
market prices directly), or the product directly via mandatory security
requirements.
Both regulations come at a cost---implementing security requirements
increases production costs, and the existence of fines decreases consumers'
values---thereby reducing the seller's profits. The focus of this paper is to
understand the \emph{efficiency} of various regulatory policies. That is,
policy A is more efficient than policy B if A more successfully minimizes
negatives externalities, while both A and B reduce seller's profits equally.
We develop a simple model to capture the impact of regulatory policies on a
buyer's behavior. {In this model, we show that for \textit{homogeneous}
markets---where the buyer's ability to follow security practices is always high
or always low---the optimal (externality-minimizing for a given profit
constraint) regulatory policy need regulate \emph{only} payments \emph{or}
production.} In arbitrary markets, by contrast, we show that while the optimal
policy may require regulating both aspects, there is always an approximately
optimal policy which regulates just one
Exotic Gapless Mott Insulators of Bosons on Multi-Leg Ladders
We present evidence for an exotic gapless insulating phase of hard-core
bosons on multi-leg ladders with a density commensurate with the number of
legs. In particular, we study in detail a model of bosons moving with direct
hopping and frustrating ring exchange on a 3-leg ladder at filling.
For sufficiently large ring exchange, the system is insulating along the ladder
but has two gapless modes and power law transverse density correlations at
incommensurate wave vectors. We propose a determinantal wave function for this
phase and find excellent comparison between variational Monte Carlo and density
matrix renormalization group calculations on the model Hamiltonian, thus
providing strong evidence for the existence of this exotic phase. Finally, we
discuss extensions of our results to other -leg systems and to -layer
two-dimensional structures.Comment: 5 pages, 4 figures; v3 is the print version; supplemental material
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Winning versus losing during gambling and its neural correlates
Humans often make decisions which maximize an internal utility function. For
example, humans often maximize their expected reward when gambling and this is
considered as a "rational" decision. However, humans tend to change their
betting strategies depending on how they "feel". If someone has experienced a
losing streak, they may "feel" that they are more likely to win on the next
hand even though the odds of the game have not changed. That is, their
decisions are driven by their emotional state. In this paper, we investigate
how the human brain responds to wins and losses during gambling. Using a
combination of local field potential recordings in human subjects performing a
financial decision-making task, spectral analyses, and non-parametric cluster
statistics, we investigated whether neural responses in different cognitive and
limbic brain areas differ between wins and losses after decisions are made. In
eleven subjects, the neural activity modulated significantly between win and
loss trials in one brain region: the anterior insula (). In particular,
gamma activity (30-70 Hz) increased in the anterior insula when subjects just
realized that they won. Modulation of metabolic activity in the anterior insula
has been observed previously in functional magnetic resonance imaging studies
during decision making and when emotions are elicited. However, our study is
able to characterize temporal dynamics of electrical activity in this brain
region at the millisecond resolution while decisions are made and after
outcomes are revealed
Stable Electromyographic Sequence Prediction During Movement Transitions using Temporal Convolutional Networks
Transient muscle movements influence the temporal structure of myoelectric
signal patterns, often leading to unstable prediction behavior from
movement-pattern classification methods. We show that temporal convolutional
network sequential models leverage the myoelectric signal's history to discover
contextual temporal features that aid in correctly predicting movement
intentions, especially during interclass transitions. We demonstrate
myoelectric classification using temporal convolutional networks to effect 3
simultaneous hand and wrist degrees-of-freedom in an experiment involving nine
human-subjects. Temporal convolutional networks yield significant
performance improvements over other state-of-the-art methods in terms of both
classification accuracy and stability.Comment: 4 pages, 5 figures, accepted for Neural Engineering (NER) 2019
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