3,417 research outputs found
Assessing statistical significance of periodogram peaks
The least-squares (or Lomb-Scargle) periodogram is a powerful tool which is
used routinely in many branches of astronomy to search for periodicities in
observational data. The problem of assessing statistical significance of
candidate periodicities for different periodograms is considered. Based on
results in extreme value theory, improved analytic estimations of false alarm
probabilities are given. They include an upper limit to the false alarm
probability (or a lower limit to the significance). These estimations are
tested numerically in order to establish regions of their practical
applicability.Comment: 7 pages, 6 figures, 1 table; To be published in MNRA
Take Care- Use Antibiotics Responsibly Swine Practitioner Project
The Take Care - Use Antibrotics Responsibly® program is an antimicrobial resistance and use educat1on and awareness program for pork producers. The program is based on principles and guidelines intended to minimize the development of antimicrobial resistance whrle maximizing animal health The program was developed by the National Pork Board, but veterinarians are key in the delivery of the program on farm. Since there are many factors that contribute to the amounts and types of antimicrobrals used on farm it was decided that the best way to measure program effectiveness was through measurement of changes in the attitude and behaviors of program particrpants
The response of Kentucky bluegrass turf to insecticidal treatments
The most common insect pests of Kentucky bluegrass (Poa pratensis L.) in Tennessee are sod webworms and white grubs. Attempts to control these insects with insecticides has, at times, resulted in the entire destruction of the lawn by sod webworms. Pass (1965) has shown that applications of aldrin, chlordane, and dieldrin increased the webworm population 2-3 fold. Streu and Vasvary (1966) found the same phenomenon in chinch bug control. Both Pass and Streu believed that this population increase of the target pest may have been related to an interference in some population-limiting mechanism, such as the natural enemies, but neither investigator definitely proved this. In view of the problem that home owners have had after applying insecticides for webworm and grub control, it was decided to conduct a study to determine the overall effects of insecticides on bluegrass. The research reported herein covers only a preliminary phase of that study: the effect of insecticides on botanical composition of a bluegrass turf
Population coding by globally coupled phase oscillators
A system of globally coupled phase oscillators subject to an external input
is considered as a simple model of neural circuits coding external stimulus.
The information coding efficiency of the system in its asynchronous state is
quantified using Fisher information. The effect of coupling and noise on the
information coding efficiency in the stationary state is analyzed. The
relaxation process of the system after the presentation of an external input is
also studied. It is found that the information coding efficiency exhibits a
large transient increase before the system relaxes to the final stationary
state.Comment: 7 pages, 9 figures, revised version, new figures added, to appear in
JPSJ Vol 75, No.
Endoscopic papillectomy: risk factors for incomplete resection and recurrence during long-term follow-up
Background
Endoscopic papillectomy is increasingly used as an alternative to surgery for ampullary adenomas and other noninvasive ampullary lesions.
Objective
To measure short-term safety and efficacy of endoscopic papillectomy, define patient and lesion characteristics associated with incomplete endoscopic resection, and measure adenoma recurrence rates during long-term follow-up.
Design
Retrospective cohort study.
Setting
Tertiary-care academic medical center.
Patients
All patients who underwent endoscopic papillectomy for ampullary lesions between July 1995 and June 2012.
Intervention
Endoscopic papillectomy.
Main Outcome Measurements
Patient and lesion characteristics associated with incomplete endoscopic resection and ampullary adenoma-free survival analysis.
Results
We identified 182 patients who underwent endoscopic papillectomy, 134 (73.6%) having complete resection. Short-term adverse events occurred in 34 (18.7%). Risk factors for incomplete resection were jaundice at presentation (odds ratio [OR] 0.21, 95% confidence interval [CI] 0.07–0.69; P = .009), occult adenocarcinoma (OR 0.06, 95% CI, 0.01–0.36; P = .002), and intraductal involvement (OR 0.29, 95% CI, 0.11–0.75; P = .011). The en bloc resection technique was strongly associated with a higher rate of complete resection (OR 4.05, 95% CI, 1.71–9.59; P = .001). Among patients with ampullary adenoma who had complete resection (n = 107), 16 patients (15%) developed recurrence up to 65 months after resection.
Limitations
Retrospective analysis.
Conclusion
Jaundice at presentation, occult adenocarcinoma in the resected specimen, and intraductal involvement are associated with a lower rate of complete resection, whereas en bloc papillectomy increases the odds of complete endoscopic resection. Despite complete resection, recurrence was observed up to 5 years after papillectomy, confirming the need for long-term surveillance
On Hilberg's Law and Its Links with Guiraud's Law
Hilberg (1990) supposed that finite-order excess entropy of a random human
text is proportional to the square root of the text length. Assuming that
Hilberg's hypothesis is true, we derive Guiraud's law, which states that the
number of word types in a text is greater than proportional to the square root
of the text length. Our derivation is based on some mathematical conjecture in
coding theory and on several experiments suggesting that words can be defined
approximately as the nonterminals of the shortest context-free grammar for the
text. Such operational definition of words can be applied even to texts
deprived of spaces, which do not allow for Mandelbrot's ``intermittent
silence'' explanation of Zipf's and Guiraud's laws. In contrast to
Mandelbrot's, our model assumes some probabilistic long-memory effects in human
narration and might be capable of explaining Menzerath's law.Comment: To appear in Journal of Quantitative Linguistic
Full potential LAPW calculation of electron momentum density and related properties of Li
Electron momentum density and Compton profiles in Lithium along , and directions are calculated using Full-Potential Linear
Augmented Plane Wave basis within generalized gradient approximation. The
profiles have been corrected for correlations with Lam-Platzman formulation
using self-consistent charge density. The first and second derivatives of
Compton profiles are studied to investigate the Fermi surface breaks. Decent
agreement is observed between recent experimental and our calculated values.
Our values for the derivatives are found to be in better agreement with
experiments than earlier theoretical results. Two-photon momentum density and
one- and two-dimensional angular correlation of positron annihilation radiation
are also calculated within the same formalism and including the
electron-positron enhancement factor.Comment: 11 pages, 7 figures TO appear in Physical Review
Benchmarking Relatedness Inference Methods with Genome-Wide Data from Thousands of Relatives
Inferring relatedness from genomic data is an essential component of genetic association studies, population genetics, forensics, and genealogy. While numerous methods exist for inferring relatedness, thorough evaluation of these approaches in real data has been lacking. Here, we report an assessment of 12 state-of-the-art pairwise relatedness inference methods using a data set with 2485 individuals contained in several large pedigrees that span up to six generations. We find that all methods have high accuracy (92–99%) when detecting first- and second-degree relationships, but their accuracy dwindles to \u3c43% for seventh-degree relationships. However, most identical by descent (IBD) segment-based methods inferred seventh-degree relatives correct to within one relatedness degree for \u3e76% of relative pairs. Overall, the most accurate methods are Estimation of Recent Shared Ancestry (ERSA) and approaches that compute total IBD sharing using the output from GERMLINE and Refined IBD to infer relatedness. Combining information from the most accurate methods provides little accuracy improvement, indicating that novel approaches, such as new methods that leverage relatedness signals from multiple samples, are needed to achieve a sizeable jump in performance
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