441 research outputs found
Detection of arbitrarily-shaped clusters using a neighbor-expanding approach: A case study on murine typhus in South Texas
<p>Abstract</p> <p>Background</p> <p>Kulldorff's spatial scan statistic has been one of the most widely used statistical methods for automatic detection of clusters in spatial data. One limitation of this method lies in the fact that it has to rely on scan windows with predefined shapes in the search process, and therefore it cannot detect cluster with arbitrary shapes. We employ a new neighbor-expanding approach and introduce two new algorithms to detect cluster with arbitrary shapes in spatial data. These two algorithms are called the maximum-likelihood-first (MLF) algorithm and non-greedy growth (NGG) algorithm. We then compare the performance of these two new algorithms with the spatial scan statistic (SaTScan), Tango's flexibly shaped spatial scan statistic (FlexScan), and Duczmal's simulated annealing (SA) method using two datasets. Furthermore, we utilize the methods to examine clusters of murine typhus cases in South Texas from 1996 to 2006.</p> <p>Result</p> <p>When compared with the SaTScan and FlexScan method, the two new algorithms were more flexible and sensitive in detecting the clusters with arbitrary shapes in the test datasets. Clusters detected by the MLF algorithm are statistically more significant than those detected by the NGG algorithm. However, the NGG algorithm appears to be more stable when there are no extreme cluster patterns in the data. For the murine typhus data in South Texas, a large portion of the detected clusters were located in coastal counties where environmental conditions and socioeconomic status of some population groups were at a disadvantage when compared with those in other counties with no clusters of murine typhus cases.</p> <p>Conclusion</p> <p>The two new algorithms are effective in detecting the location and boundary of spatial clusters with arbitrary shapes. Additional research is needed to better understand the etiology of the concentration of murine typhus cases in some counties in south Texas.</p
Andreev Reflection without Fermi surface alignment in High T-Topological heterostructures
We address the controversy over the proximity effect between topological
materials and high T superconductors. Junctions are produced between
BiSrCaCuO and materials with different Fermi
surfaces (BiTe \& graphite). Both cases reveal tunneling spectra
consistent with Andreev reflection. This is confirmed by magnetic field that
shifts features via the Doppler effect. This is modeled with a single parameter
that accounts for tunneling into a screening supercurrent. Thus the tunneling
involves Cooper pairs crossing the heterostructure, showing the Fermi surface
mis-match does not hinder the ability to form transparent interfaces, which is
accounted for by the extended Brillouin zone and different lattice symmetries
Evidence for a New Excitation at the Interface Between a High-Tc Superconductor and a Topological Insulator
High-temperature superconductors exhibit a wide variety of novel excitations.
If contacted with a topological insulator, the lifting of spin rotation
symmetry in the surface states can lead to the emergence of unconventional
superconductivity and novel particles. In pursuit of this possibility, we
fabricated high critical-temperature (Tc ~ 85 K) superconductor/topological
insulator (Bi2Sr2CaCu2O8+delta/Bi2Te2Se) junctions. Below 75 K, a zero-bias
conductance peak (ZBCP) emerges in the differential conductance spectra of this
junction. The magnitude of the ZBCP is suppressed at the same rate for magnetic
fields applied parallel or perpendicular to the junction. Furthermore, it can
still be observed and does not split up to at least 8.5 T. The temperature and
magnetic field dependence of the excitation we observe appears to fall outside
the known paradigms for a ZBCP
Fluctuations of the Condensate in Ideal and Interacting Bose Gases
We investigate the fluctuations of the condensate in the ideal and weakly
interacting Bose gases confined in a box of volume V within canonical ensemble.
Canonical ensemble is developed to describe the behavior of the fluctuations
when different methods of approximation to the weakly interacting Bose gases
are used. Research shows that the fluctuations of the condensate exhibit
anomalous behavior for the interacting Bose gas confined in a box.Comment: RevTex, 4 Figs,E-mail:[email protected], corrected typo
Anomalous particle-number fluctuations in a three-dimensional interacting Bose-Einstein condensate
The particle-number fluctuations originated from collective excitations are
investigated for a three-dimensional, repulsively interacting Bose-Einstein
condensate (BEC) confined in a harmonic trap. The contribution due to the
quantum depletion of the condensate is calculated and the explicit expression
of the coefficient in the formulas denoting the particle-number fluctuations is
given. The results show that the particle-number fluctuations of the condensate
follow the law and the fluctuations vanish when
temperature approaches to the BEC critical temperature.Comment: RevTex, 4 page
Treatment of port wastes according to the paradigm of the circular economy
The problem of the presence of waste in the marine environment has recently taken on the dimensions of a complex and global challenge. In an effort to reduce both the economic and environmental costs of managing port waste, many ports are looking for sustainable solutions for marine waste management.
Plasma-assisted gasification (PAG) is an innovative combination of two technologies, namely plasma treatment and gasification, which can be used to efficiently convert carbon-containing wastes to a clean syngas (H2 + CO). The latter can be used to generate electricity directly in gas engines, dual-fuel generators, gas turbines or fuel cells. PAG provides several key benefits which allow removing all the environmental, regulatory and commercial risks typically associated with the potential eco-toxicity of leachable bottom ash produced by incinerators or other thermal processes. PAG does not produce any waste (zero waste), reduces the need for landfilling of waste, and produces a high-value construction material (Plasmarok) which is recognized as a product. All these reasons make PAG a technology capable of optimally solving waste management in ports in line with a circular economy logic.
This study is based upon the IMPATTI-NO Project (Interreg IT-FR Maritime Program 2014–2020) which implements several laboratory applications aimed at the chemical-physical treatment of the non-recyclable waste containing plastics deriving from the collection of beached waste and wastes collected by fishermen’s trawls and passenger ships. To demonstrate the effectiveness of PAG for the treatment of port waste, IMPATTI-NO performs experimental tests that simulate PAG pilot plants using artificial samples representative of port waste.
This paper describes the research path developed so far and the preparatory elements that led to the definition of specifications for the sampling and collection of port waste
Prenatal smoke effect on mouse offspring Igf1 promoter methylation from fetal stage to adulthood is organ- and sex-specific
Prenatal smoke exposure (PSE) is associated with reduced birth weight, impaired fetal development, and increased risk for diseases later in life. Changes in DNA methylation may be involved, as multiple large-scale epigenome-wide association studies showed that PSE is robustly associated with DNA methylation changes in blood among offspring in early life. Insulin-like growth factor-1 (IGF1) is important in growth, differentiation, and repair processes after injury. However, no studies investigated the organ-specific persistence of PSE-induced methylation change of Igf1 into adulthood. Based on our previous studies on the PSE effect on Igf1 promoter methylation in fetal and neonatal mouse offspring, we now have extended our studies to adulthood. Our data show that basal Igf1 promoter methylation generally increased in the lung but decreased in the liver (except for 2 persistent CpG sites in both organs) across three different developmental stages. PSE changed Igf1 promoter methylation in all three developmental stages, which was organ and sex specific. The PSE effect was less pronounced in adult offspring compared with the fetal and neonatal stages. In addition, the PSE effect in the adult stage was more pronounced in the lung compared with the liver. For most CpG sites, an inverse correlation was found for promoter methylation and mRNA expression when the data of all three stages were combined. This was more prominent in the liver. Our findings provide additional evidence for sex- and organ-dependent prenatal programming, which supports the developmental origins of health and disease (DOHaD) hypothesis
Broadband Radio Spectral Observations of Solar Eclipse on 2008-08-01 and Implications on the Quiet Sun Atmospheric Model
Based on the joint-observations of the radio broadband spectral emissions of
solar eclipse on August 1, 2008 at Jiuquan (total eclipse) and Huairou (partial
eclipse) at the frequencies of 2.00 -- 5.60 GHz (Jiuquan), 2.60 -- 3.80 GHZ
(Chinese solar broadband radiospectrometer, SBRS/Huairou), and 5.20 -- 7.60 GHz
(SBRS/Huairou), the authors assemble a successive series of broadband spectrum
with a frequency of 2.60 -- 7.60 GHz to observe the solar eclipse
synchronously. This is the first attempt to analyze the solar eclipse radio
emission under the two telescopes located at different places with broadband
frequencies in the periods of total and partial eclipse. With these analyses,
the authors made a new semiempirical model of the coronal plasma density of the
quiet Sun and made a comparison with the classic models.Comment: 10 pages, 4 figures, published on Sci. China Ser. G, 2009, Vol.52,
page 1765-177
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