2,570 research outputs found
Agents Play Mix-game
In mix-game which is an extension of minority game, there are two groups of
agents; group1 plays the majority game, but the group2 plays the minority game.
This paper studies the change of the average winnings of agents and
volatilities vs. the change of mixture of agents in mix-game model. It finds
that the correlations between the average winnings of agents and the mean of
local volatilities are different with different combinations of agent memory
length when the proportion of agents in group 1 increases. This study result
suggests that memory length of agents in group1 be smaller than that of agent
in group2 when mix-game model is used to simulate the financial markets.Comment: 8 pages, 6 figures, 3 table
Binary Tree Approach to Scaling in Unimodal Maps
Ge, Rusjan, and Zweifel (J. Stat. Phys. 59, 1265 (1990)) introduced a binary
tree which represents all the periodic windows in the chaotic regime of
iterated one-dimensional unimodal maps. We consider the scaling behavior in a
modified tree which takes into account the self-similarity of the window
structure. A non-universal geometric convergence of the associated superstable
parameter values towards a Misiurewicz point is observed for almost all binary
sequences with periodic tails. There are an infinite number of exceptional
sequences, however, which lead to superexponential scaling. The origin of such
sequences is explained.Comment: 25 pages, plain Te
A1C to Detect Diabetes in Healthy Adults: When should we recheck?
OBJECTIVE: To evaluate the optimal interval for rechecking A1C levels below the diagnostic threshold of 6.5% for healthy adults. RESEARCH DESIGN AND METHODS: This was a retrospective cohort study. Participants were 16,313 apparently healthy Japanese adults not taking glucose-lowering medications at baseline. Annual A1C measures from 2005 to 2008 at the Center for Preventive Medicine, a community teaching hospital in Japan, estimated cumulative incidence of diabetes. RESULTS: Mean age (+/-SD) of participants was 49.7 +/- 12.3 years, and 53% were male. Mean A1C at baseline was 5.4 +/- 0.5%. At 3 years, for those with A1C at baseline of <5.0%, 5.0-5.4%, 5.5-5.9%, and 6.0-6.4%, cumulative incidence (95% CI) was 0.05% (0.001-0.3), 0.05% (0.01-0.11), 1.2% (0.9-1.6), and 20% (18-23), respectively. CONCLUSIONS: In those with an A1C <6.0%, rescreening at intervals shorter than 3 years identifies few individuals (approximately or=6.5%.</or=1%)
Cloud condensation nuclei in pristine tropical rainforest air of Amazonia: size-resolved measurements and modeling of atmospheric aerosol composition and CCN activity
Atmospheric aerosol particles serving as cloud condensation nuclei (CCN) are
key elements of the hydrological cycle and climate. We have measured and
characterized CCN at water vapor supersaturations in the range of <i>S</i>=0.10–0.82%
in pristine tropical rainforest air during the AMAZE-08 campaign in central Amazonia.
<br><br>
The effective hygroscopicity parameters describing the influence of chemical
composition on the CCN activity of aerosol particles varied in the range of
κ≈0.1–0.4 (0.16±0.06 arithmetic mean and standard deviation).
The overall median value of κ≈0.15 was by a factor of two lower
than the values typically observed for continental aerosols in other regions
of the world. Aitken mode particles were less hygroscopic than accumulation
mode particles (κ≈0.1 at <i>D</i>≈50 nm; κ≈0.2 at
<i>D</i>≈200 nm), which is in agreement with earlier hygroscopicity tandem
differential mobility analyzer (H-TDMA) studies.
<br><br>
The CCN measurement results are consistent with aerosol mass spectrometry
(AMS) data, showing that the organic mass fraction (<i>f</i><sub>org</sub>) was
on average as high as ~90% in the Aitken mode (<i>D</i>≤100 nm) and
decreased with increasing particle diameter in the accumulation mode
(~80% at <i>D</i>≈200 nm). The κ values exhibited a negative linear
correlation with <i>f</i><sub>org</sub> (<i>R</i><sup>2</sup>=0.81), and extrapolation yielded the
following effective hygroscopicity parameters for organic and inorganic
particle components: κ<sub>org</sub>≈0.1 which can be regarded as the
effective hygroscopicity of biogenic secondary organic aerosol (SOA) and
κ<sub>inorg</sub>≈0.6 which is characteristic for ammonium sulfate and
related salts. Both the size dependence and the temporal variability of
effective particle hygroscopicity could be parameterized as a function of
AMS-based organic and inorganic mass fractions (κ<sub>p</sub>=κ<sub>org</sub>×<i>f</i><sub>org</sub>
+κ<sub>inorg</sub>×<i>f</i><sub>inorg</sub>).
The CCN number concentrations
predicted with κ<sub>p</sub> were in fair agreement with the measurement results
(~20% average deviation). The median CCN number concentrations at
<i>S</i>=0.1–0.82% ranged from <i>N</i><sub>CCN,0.10</sub>≈35 cm<sup>−3</sup> to
<i>N</i><sub>CCN,0.82</sub>≈160 cm<sup>−3</sup>, the median concentration of aerosol
particles larger than 30 nm was <i>N</i><sub>CN,30</sub>≈200 cm<sup>−3</sup>, and the
corresponding integral CCN efficiencies were in the range of
<i>N</i><sub>CCN,0.10</sub>/<i>N</i><sub>CN,30</sub>≈0.1 to <i>N</i><sub>CCN,0.82</sub>/<i>N</i><sub>CN,30</sub>≈0.8.
<br><br>
Although the number concentrations and hygroscopicity parameters were much
lower in pristine rainforest air, the integral CCN efficiencies observed
were similar to those in highly polluted megacity air. Moreover, model
calculations of <i>N</i><sub>CCN,<i>S</i></sub> assuming an approximate global average value of
κ≈0.3 for continental aerosols led to systematic overpredictions,
but the average deviations exceeded ~50% only at low water vapor
supersaturation (0.1%) and low particle number concentrations (≤100 cm<sup>−3</sup>).
Model calculations assuming a constant aerosol size distribution
led to higher average deviations at all investigated levels of
supersaturation: ~60% for the campaign average distribution and
~1600% for a generic remote continental size distribution. These
findings confirm earlier studies suggesting that aerosol particle number and
size are the major predictors for the variability of the CCN concentration
in continental boundary layer air, followed by particle composition and
hygroscopicity as relatively minor modulators.
<br><br>
Depending on the required and applicable level of detail, the information
and parameterizations presented in this paper should enable efficient
description of the CCN properties of pristine tropical rainforest aerosols
of Amazonia in detailed process models as well as in large-scale atmospheric
and climate models
Hysteresis of Electronic Transport in Graphene Transistors
Graphene field effect transistors commonly comprise graphene flakes lying on
SiO2 surfaces. The gate-voltage dependent conductance shows hysteresis
depending on the gate sweeping rate/range. It is shown here that the
transistors exhibit two different kinds of hysteresis in their electrical
characteristics. Charge transfer causes a positive shift in the gate voltage of
the minimum conductance, while capacitive gating can cause the negative shift
of conductance with respect to gate voltage. The positive hysteretic phenomena
decay with an increase of the number of layers in graphene flakes. Self-heating
in helium atmosphere significantly removes adsorbates and reduces positive
hysteresis. We also observed negative hysteresis in graphene devices at low
temperature. It is also found that an ice layer on/under graphene has much
stronger dipole moment than a water layer does. Mobile ions in the electrolyte
gate and a polarity switch in the ferroelectric gate could also cause negative
hysteresis in graphene transistors. These findings improved our understanding
of the electrical response of graphene to its surroundings. The unique
sensitivity to environment and related phenomena in graphene deserve further
studies on nonvolatile memory, electrostatic detection and chemically driven
applications.Comment: 13 pages, 6 Figure
Does shear wave ultrasound independently predict axillary lymph node metastasis in women with invasive breast cancer?
Shear wave elastography (SWE) shows promise as an adjunct to greyscale ultrasound examination in assessing breast masses. In breast cancer, higher lesion stiffness on SWE has been shown to be associated with features of poor prognosis. The purpose of this study was to assess whether lesion stiffness at SWE is an independent predictor of lymph node involvement. Patients with invasive breast cancer treated by primary surgery, who had undergone SWE examination were eligible. Data were retrospectively analysed from 396 consecutive patients. The mean stiffness values were obtained using the Aixplorer(®) ultrasound machine from SuperSonic Imagine Ltd. Measurements were taken from a region of interest positioned over the stiffest part of the abnormality. The average of the mean stiffness value obtained from each of two orthogonal image planes was used for analysis. Associations between lymph node involvement and mean lesion stiffness, invasive cancer size, histologic grade, tumour type, ER expression, HER-2 status and vascular invasion were assessed using univariate and multivariate logistic regression. At univariate analysis, invasive size, histologic grade, HER-2 status, vascular invasion, tumour type and mean stiffness were significantly associated with nodal involvement. Nodal involvement rates ranged from 7 % for tumours with mean stiffness <50 kPa to 41 % for tumours with a mean stiffness of >150 kPa. At multivariate analysis, invasive size, tumour type, vascular invasion, and mean stiffness maintained independent significance. Mean stiffness at SWE is an independent predictor of lymph node metastasis and thus can confer prognostic information additional to that provided by conventional preoperative tumour assessment and staging
Congenital anomalies in low- and middle-income countries: the unborn child of global surgery.
Surgically correctable congenital anomalies cause a substantial burden of global morbidity and mortality. These anomalies disproportionately affect children in low- and middle-income countries (LMICs) due to sociocultural, economic, and structural factors that limit the accessibility and quality of pediatric surgery. While data from LMICs are sparse, available evidence suggests that the true human and financial cost of congenital anomalies is grossly underestimated and that pediatric surgery is a cost-effective intervention with the potential to avert significant premature mortality and lifelong disability
What is the real impact of acute kidney injury?
Background: Acute kidney injury (AKI) is a common clinical problem. Studies have documented the incidence of AKI in a variety of populations but to date we do not believe the real incidence of AKI has been accurately documented in a district general hospital setting. The aim here was to describe the detected incidence of AKI in a typical general hospital setting in an unselected population, and describe associated short and long-term outcomes. Methods: A retrospective observational database study from secondary care in East Kent (adult catchment population of 582,300). All adult patients (18 years or over) admitted between 1st February 2009 and 31st July 2009, were included. Patients receiving chronic renal replacement therapy (RRT), maternity and day case admissions were excluded. AKI was defined by the acute kidney injury network (AKIN) criteria. A time dependent risk analysis with logistic regression and Cox regression was used for the analysis of in-hospital mortality and survival. Results: The incidence of AKI in the 6 month period was 15,325 pmp/yr (adults) (69% AKIN1, 18% AKIN2 and 13% AKIN3). In-hospital mortality, length of stay and ITU utilisation all increased with severity of AKI. Patients with AKI had an increase in care on discharge and an increase in hospital readmission within 30 days. Conclusions: This data comes closer to the real incidence and outcomes of AKI managed in-hospital than any study published in the literature to date. Fifteen percent of all admissions sustained an episode of AKI with increased subsequent short and long term morbidity and mortality, even in those with AKIN1. This confers an increased burden and cost to the healthcare economy, which can now be quantified. These results will furnish a baseline for quality improvement projects aimed at early identification, improved management, and where possible prevention, of AKI
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Inorganic and Radiochemical Analysis of AW-101 and AN-107 ''Diluted Feed'' Materials
This report presents the inorganic and radiochemical analytical results for AW-101 and AN-107 diluted feed materials. The analyses were conducted in support of the BNFL Proposal No. 29952/29953 Task 2.1. The inorganic and radiochemical analysis results obtained from the diluted feed materials are used to provide initial characterization information for subsequent processing testing. Quality Assurance (QA) Plan MCS-033 provides the operational and quality control protocols for the analytical activities
Isoprenoid Pathway Optimization for Taxol Precursor Overproduction in Escherichia coli
Author Manuscript February 6, 2011Taxol (paclitaxel) is a potent anticancer drug first isolated from the Taxus brevifolia Pacific yew tree. Currently, cost-efficient production of Taxol and its analogs remains limited. Here, we report a multivariate-modular approach to metabolic-pathway engineering that succeeded in increasing titers of taxadiene—the first committed Taxol intermediate—approximately 1 gram per liter (~15,000-fold) in an engineered Escherichia coli strain. Our approach partitioned the taxadiene metabolic pathway into two modules: a native upstream methylerythritol-phosphate (MEP) pathway forming isopentenyl pyrophosphate and a heterologous downstream terpenoid–forming pathway. Systematic multivariate search identified conditions that optimally balance the two pathway modules so as to maximize the taxadiene production with minimal accumulation of indole, which is an inhibitory compound found here. We also engineered the next step in Taxol biosynthesis, a P450-mediated 5α-oxidation of taxadiene to taxadien-5α-ol. More broadly, the modular pathway engineering approach helped to unlock the potential of the MEP pathway for the engineered production of terpenoid natural products
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