4,727 research outputs found
Trapping reactions with subdiffusive traps and particles characterized by different anomalous diffusion exponents
A number of results for reactions involving subdiffusive species all with the
same anomalous exponent gamma have recently appeared in the literature and can
often be understood in terms of a subordination principle whereby time t in
ordinary diffusion is replaced by t^gamma. However, very few results are known
for reactions involving different species characterized by different anomalous
diffusion exponents. Here we study the reaction dynamics of a (sub)diffusive
particle surrounded by a sea of (sub)diffusive traps in one dimension. We find
rigorous results for the asymptotic survival probability of the particle in
most cases, with the exception of the case of a particle that diffuses normally
while the anomalous diffusion exponent of the traps is smaller than 2/3.Comment: To appear in Phys. Rev.
The Potential of Restarts for ProbSAT
This work analyses the potential of restarts for probSAT, a quite successful
algorithm for k-SAT, by estimating its runtime distributions on random 3-SAT
instances that are close to the phase transition. We estimate an optimal
restart time from empirical data, reaching a potential speedup factor of 1.39.
Calculating restart times from fitted probability distributions reduces this
factor to a maximum of 1.30. A spin-off result is that the Weibull distribution
approximates the runtime distribution for over 93% of the used instances well.
A machine learning pipeline is presented to compute a restart time for a
fixed-cutoff strategy to exploit this potential. The main components of the
pipeline are a random forest for determining the distribution type and a neural
network for the distribution's parameters. ProbSAT performs statistically
significantly better than Luby's restart strategy and the policy without
restarts when using the presented approach. The structure is particularly
advantageous on hard problems.Comment: Eurocast 201
Patient-reported aesthetic outcomes of upper blepharoplasty:a randomized controlled trial comparing two surgical techniques
It is not yet established whether additional orbicularis oculi muscle excision leads to better patient-reported aesthetic outcomes (PRO) compared to a skin-only resection blepharoplasty. A double-blind randomized controlled trial of upper blepharoplasty, with or without muscle excision, was performed on 54 White European patients who assessed the procedure via PRO. FACE-Q questionnaires covering eyes in general, upper eyelids, forehead and eyebrows, overall face, age appearance appraisal, age appraisal, social functioning, satisfaction with the outcome, and adverse effects were completed preoperatively and at 6 and 12 months after upper blepharoplasty. The Patient and Observer Scar Assessment Scale was used to assess scarring. The FACE-Q scores for skin-only and skin/muscle upper blepharoplasty were similar regarding the upper eyelids, forehead and eyebrows, overall face, patient perceived aging and age, social functioning, and satisfaction with the results, and also increased for both procedures with time. The FACE-Q score regarding the eyes in general was higher in the skin-only group at the 12-month follow-up. Scarring and adverse effects did not differ between the groups. Additional muscle resection does not seem to influence patient satisfaction. Thus, when performing an upper blepharoplasty, there is no need for additional muscle resection as a routine procedure to improve patient satisfaction
The target problem with evanescent subdiffusive traps
We calculate the survival probability of a stationary target in one dimension
surrounded by diffusive or subdiffusive traps of time-dependent density. The
survival probability of a target in the presence of traps of constant density
is known to go to zero as a stretched exponential whose specific power is
determined by the exponent that characterizes the motion of the traps. A
density of traps that grows in time always leads to an asymptotically vanishing
survival probability. Trap evanescence leads to a survival probability of the
target that may be go to zero or to a finite value indicating a probability of
eternal survival, depending on the way in which the traps disappear with time
Geometric and dynamic perspectives on phase-coherent and noncoherent chaos
Statistically distinguishing between phase-coherent and noncoherent chaotic
dynamics from time series is a contemporary problem in nonlinear sciences. In
this work, we propose different measures based on recurrence properties of
recorded trajectories, which characterize the underlying systems from both
geometric and dynamic viewpoints. The potentials of the individual measures for
discriminating phase-coherent and noncoherent chaotic oscillations are
discussed. A detailed numerical analysis is performed for the chaotic R\"ossler
system, which displays both types of chaos as one control parameter is varied,
and the Mackey-Glass system as an example of a time-delay system with
noncoherent chaos. Our results demonstrate that especially geometric measures
from recurrence network analysis are well suited for tracing transitions
between spiral- and screw-type chaos, a common route from phase-coherent to
noncoherent chaos also found in other nonlinear oscillators. A detailed
explanation of the observed behavior in terms of attractor geometry is given.Comment: 12 pages, 13 figure
Reproducibility of 3D scanning in the periorbital region
The reproducibility of scanning in the periorbital region with 3D technology to enable objective evaluations of surgical treatment in the periorbital region was assessed. Facial 3D-scans of 15 volunteers were captured at different time points with a handheld Artec Space Spider structured light scanner. Two scans were made with a one minute interval and repeated after 1 year; for both a natural head position and with the head in a fixation-device. On assessing the area between the eyelashes and eyebrows, the medians of the average deviations between the various cross-sections of the one minute interval 3D-scans ranged from 0.17 to 0.21 mm at baseline, and from 0.10 to 0.11 mm when the minute-interval scanning was repeated one year later. The systematic differences when scanning in a natural head position and fixated position were comparable. The reproducibility of the 3D processing was excellent (intraclass correlation coefficient > 0.9). The repeated scanning deviations (baseline versus one year data) were well within the accepted clinical threshold of 1 mm. Scanning with a hand-held 3D-scanning device (Artec Space Spider) is a promising tool to assess changes in the periorbital region following surgical treatment since the median deviations are well below the clinically accepted 1 mm measuring error, for both the natural head and fixated positions
Cognitive Impairment among Older Adults in the Emergency Department
Background: Within the next 30 years, the number of visits older adults will make to emergency departments (EDs) is expected to double from 16 million, or 14% of all visits, to 34 million and comprise nearly a quarter of all visits.Objective: The objectives of this study were to determine prevalence rates of cognitive impairment among older adults in the ED and to identify associations, if any, between environmental factors unique to the ED and rates of cognitive impairment.Methods: A cross-sectional observational study of adults 65 and older admitted to the ED of a large, urban, tertiary academic health center was conducted between September 2007 and May 2008. Patients were screened for cognitive impairment in orientation, recall and executive function using the Six-Item Screen (SIS) and the CLOX1, clock drawing task. Cognitive impairment among this ED population was assessed and both patient demographics and ED characteristics (crowding, triage time, location of assessment, triage class) were compared through adjusted generalized linear models.Results: Forty-two percent (350/829) of elderly patients presented with deficits in orientation and recall as assessed by the SIS. An additional 36% of elderly patients with no impairment in orientation or recall had deficits in executive function as assessed by the CLOX1. In full model adjusted analyses patients were more likely to screen deficits in orientation and recall (SIS) if they were 85 years or older (Relative Risk [RR]=1.63, 95% Confidence Interval [95% CI]=1.3-2.07), black (RR=1.85, 95% CI=1.5-2.4) and male (RR=1.42, 95% CI=1.2-1.7). Only age was significantly associated with executive functioning deficits in the ED screened using the clock drawing task (CLOX1) (75-84 years: RR=1.35, 95% CI= 1.2-1.6; 85+ years: RR=1.69, 95% CI= 1.5-2.0).Conclusion: These findings have several implications for patients seen in the ED. The SIS coupled with a clock drawing task (CLOX1) provide a rapid and simple method for assessing and documenting cognition when lengthier assessment tools are not feasible and add to the literature on the use of these tools in the ED. Further research on provider use of these tools and potential implication for quality improvement is needed. [West J Emerg Med. 2011; 12(1):56-62.
Analysis of phosphatases in ER-negative breast cancers identifies DUSP4 as a critical regulator of growth and invasion.
Estrogen receptor (ER)-negative cancers have a poor prognosis, and few targeted therapies are available for their treatment. Our previous analyses have identified potential kinase targets critical for the growth of ER-negative, progesterone receptor (PR)-negative and HER2-negative, or "triple-negative" breast cancer (TNBC). Because phosphatases regulate the function of kinase signaling pathways, in this study, we investigated whether phosphatases are also differentially expressed in ER-negative compared to those in ER-positive breast cancers. We compared RNA expression in 98 human breast cancers (56 ER-positive and 42 ER-negative) to identify phosphatases differentially expressed in ER-negative compared to those in ER-positive breast cancers. We then examined the effects of one selected phosphatase, dual specificity phosphatase 4 (DUSP4), on proliferation, cell growth, migration and invasion, and on signaling pathways using protein microarray analyses of 172 proteins, including phosphoproteins. We identified 48 phosphatase genes are significantly differentially expressed in ER-negative compared to those in ER-positive breast tumors. We discovered that 31 phosphatases were more highly expressed, while 11 were underexpressed specifically in ER-negative breast cancers. The DUSP4 gene is underexpressed in ER-negative breast cancer and is deleted in approximately 50 % of breast cancers. Induced DUSP4 expression suppresses both in vitro and in vivo growths of breast cancer cells. Our studies show that induced DUSP4 expression blocks the cell cycle at the G1/S checkpoint; inhibits ERK1/2, p38, JNK1, RB, and NFkB p65 phosphorylation; and inhibits invasiveness of TNBC cells. These results suggest that that DUSP4 is a critical regulator of the growth and invasion of triple-negative breast cancer cells
Statistical mechanics of error exponents for error-correcting codes
Error exponents characterize the exponential decay, when increasing message
length, of the probability of error of many error-correcting codes. To tackle
the long standing problem of computing them exactly, we introduce a general,
thermodynamic, formalism that we illustrate with maximum-likelihood decoding of
low-density parity-check (LDPC) codes on the binary erasure channel (BEC) and
the binary symmetric channel (BSC). In this formalism, we apply the cavity
method for large deviations to derive expressions for both the average and
typical error exponents, which differ by the procedure used to select the codes
from specified ensembles. When decreasing the noise intensity, we find that two
phase transitions take place, at two different levels: a glass to ferromagnetic
transition in the space of codewords, and a paramagnetic to glass transition in
the space of codes.Comment: 32 pages, 13 figure
On the exchange of intersection and supremum of sigma-fields in filtering theory
We construct a stationary Markov process with trivial tail sigma-field and a
nondegenerate observation process such that the corresponding nonlinear
filtering process is not uniquely ergodic. This settles in the negative a
conjecture of the author in the ergodic theory of nonlinear filters arising
from an erroneous proof in the classic paper of H. Kunita (1971), wherein an
exchange of intersection and supremum of sigma-fields is taken for granted.Comment: 20 page
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