479 research outputs found
On the Spectra of Real and Complex Lam\'e Operators
We study Lam\'e operators of the form with and a
half-period of . For rectangular period lattices, we can choose
and such that the potential is real, periodic and regular. It is
known after Ince that the spectrum of the corresponding Lam\'e operator has a
band structure with not more than gaps. In the first part of the paper, we
prove that the opened gaps are precisely the first ones. In the second
part, we study the Lam\'e spectrum for a generic period lattice when the
potential is complex-valued. We concentrate on the case, when the
spectrum consists of two regular analytic arcs, one of which extends to
infinity, and briefly discuss the case, paying particular attention to
the rhombic lattices
Evaluation of Bone Remodeling in Hemodialysis Patients: Serum Biochemistry, Circulating Cytokines and Bone Histomorphometry
BACKGROUND: To optimize the noninvasive evaluation of bone remodeling, we evaluated, besides routine serum markers, serum levels of several cytokines involved in bone turnover.
METHODS: A transiliac bone biopsy was performed in 47 hemodialysis patients. Serum levels of intact parathyroid hormone (iPTH; 1-84), total alkaline phosphatases (tAP), calcium, phosphate and aluminum (Al) were measured. Circulating levels of interleukin-6 (IL-6), IL-1 receptor antagonist (IL-1Ra) and soluble IL-6 receptor (sIL-6r) were determined using ELISA. Circulating IL-1beta, IL-6, IL-8, IL-10, IL-12p70 and tumor necrosis factor-alpha (TNF-alpha) were simultaneously quantified by flow cytometric immunoassay.
RESULTS: Patients with low/normal bone formation rate (L/N-BFR) had significantly lower serum iPTH (p300 pg/mL in association with tAP >120 U/L showed low sensitivity (58.8%) and low negative predictive value (44.0%) for the diagnosis of high BFR disease. An iPTH <300 pg/mL in association with normal or low tAP, <120 U/L, was associated with low sensitivity (66.7%) but high specificity (97.1%) for the diagnosis of L/N-BFR. Serum IL-1, IL-6, IL-12p70 and TNF-alpha were positively correlated with BFR, serum IL1-Ra and IL-10 with bone area, and by multiple regression analysis, tAP and IL-6 were independently predictive of BFR.
CONCLUSIONS: Significant associations were found between several circulating cytokines and bone histomorphometry in dialysis patients. The usefulness of these determinations in the noninvasive evaluation of bone remodeling needs to be confirmed in larger dialysis populations
The semi-presidential system of Cape Verde: the relationship between the executive and the legislative powers = O sistema semi-presidencialista caboverdiano: a relação entre os poderes executivo e legislativo
e article analyses the relationship established between the executive
and legislative powers in the Cape Verdean government system
where researchers seek to understand it, taking into account their theoretical
and constitutional setting practice. It should be noted the prominence
of the debate and studies undertaken to understand how the scienti c
academy seeks to eradicate this problem. Two issues are relevant in this
debate: the rst reporting to the theoretical and constitutional con guration
of Cape Verdean government system and the other to its policy and
legislative practice.
Keywords: Cape Verde. Semi-presidential System. Systems of Government.
Legislative and Executive Powers.O artigo procura analisar a relação que se estabelece entre o poder
executivo e legislativo no sistema de governo cabo-verdiano, onde Investigadores
buscam compreendê-lo, tendo em conta a sua con guração
prática, teórica e constitucional. Há que realçar a proeminência do debate
e dos estudos realizados no sentido de compreender como é que a academia
cientí ca procura debelar esta problemática. Duas questões são
pertinentes neste debate: a primeira refere-se à con guração teórico-constitucional
do sistema de governo cabo-verdiano e a outra à prática política
e legislativa.
Palavras-chave: Cabo Verde. Sistema Semi-presidencialista. Sistemas de Governo.
Poder legislativo e Poder Executivo
Fission Yeast Does Not Age under Favorable Conditions, but Does So after Stress
SummaryBackgroundMany unicellular organisms age: as time passes, they divide more slowly and ultimately die. In budding yeast, asymmetric segregation of cellular damage results in aging mother cells and rejuvenated daughters. We hypothesize that the organisms in which this asymmetry is lacking, or can be modulated, may not undergo aging.ResultsWe performed a complete pedigree analysis of microcolonies of the fission yeast Schizosaccharomyces pombe growing from a single cell. When cells were grown under favorable conditions, none of the lineages exhibited aging, which is defined as a consecutive increase in division time and increased death probability. Under favorable conditions, few cells died, and their death was random and sudden rather than following a gradual increase in division time. Cell death correlated with the inheritance of Hsp104-associated protein aggregates. After stress, the cells that inherited large aggregates aged, showing a consecutive increase in division time and an increased death probability. Their sisters, who inherited little or no aggregates, did not age.ConclusionsWe conclude that S. pombe does not age under favorable growth conditions, but does so under stress. This transition appears to be passive rather than active and results from the formation of a single large aggregate, which segregates asymmetrically at the subsequent cell division. We argue that this damage-induced asymmetric segregation has evolved to sacrifice some cells so that others may survive unscathed after severe environmental stresses
Stochastic Reconstruction and Interpolation of Precipitation Fields Using Combined Information of Commercial Microwave Links and Rain Gauges
For the reconstruction and interpolation of precipitation fields, we present the application of a stochastic approach called Random Mixing. Generated fields are based on a data set consisting of rain gauge observations and path-averaged rain rates estimated using Commercial Microwave Link (CML) derived information. Precipitation fields are received as linear combination of unconditional spatial random fields, where the spatial dependence structure is described by copulas. The weights of the linear combination are optimized such that the observations and the spatial structure of the precipitation observations are reproduced. The innovation of the approach is that this strategy enables the simulation of ensembles of precipitation fields of any size. Each ensemble member is in concordance with the observed path-averaged CML derived rain rates and additionally reflects the observed rainfall variability along the CML paths. The ensemble spread allows additionally an estimation of the uncertainty of the reconstructed precipitation fields. The method is demonstrated both for a synthetic data set and a real-world data set in South Germany. While the synthetic example allows an evaluation against a known reference, the second example demonstrates the applicability for real-world observations. Generated precipitation fields of both examples reproduce the spatial precipitation pattern in good quality. A performance evaluation of Random Mixing compared to Ordinary Kriging demonstrates an improvement of the reconstruction of the observed spatial variability. Random Mixing is concluded to be a beneficial new approach for the provision of precipitation fields and ensembles of them, in particular when different measurement types are combined
Posterior musculofascial reconstruction after radical prostatectomy: an updated systematic review and a meta-analysis
To evaluate the influence of posterior musculofascial plate reconstruction (PR) on early return of continence after radical prostatectomy (RP); an updated systematic review of the literature. A systematic review of the literature was performed in June 2015, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and searching Medline, Embase, Scopus and Web of Science databases. We searched the terms posterior reconstruction prostatectomy, double layer anastomosis prostatectomy across the 'Title' and 'Abstract' fields of the records, with the following limits: humans, gender (male), and language (English). The authors reviewed the records to identify studies comparing cohorts of patients who underwent RP with or without restoration of the posterior aspect of the rhabdosphincter. A meta-analysis of the risk ratios estimated using data from the selected studies was performed. In all, 21 studies were identified, including three randomised controlled trials. The overall analysis of comparative studies showed that PR improved early continence recovery at 3-7, 30, and 90 days after catheter removal, while the continence rate at 180 days was statistically but not clinically affected. Statistically significantly lower anastomotic leakage rates were described after PR. There were no significant differences for positive surgical margins rates or for complications such as acute urinary retention and bladder neck stricture. The analysis confirms the benefits at 30 days after catheter removal already discussed in the review published in 2012, but also shows a significant advantage in terms of urinary continence recovery in the first 90 days. A multicentre prospective randomised controlled trial is currently being conducted in several institutions around the world to better assess the effectiveness of PR in facilitating an earlier recovery of postoperative urinary continence
GaMin’11 – an International Inter-laboratory Comparison for Geochemical CO2 - Saline Fluid - Mineral Interaction Experiments
Due to the strong interest in geochemical CO2-fluid-rock interaction in the context of geological storage of CO2 a growing number of research groups have used a variety of different experimental ways to identify important geochemical dissolution or precipitation reactions and – if possible – quantify the rates and extent of mineral or rock alteration. In this inter-laboratory comparison the gas-fluid-mineral reactions of three samples of rock-forming minerals have been investigated by 11 experimental labs. The reported results point to robust identification of the major processes in the experiments by most groups. The dissolution rates derived from the changes in composition of the aqueous phase are consistent overall, but the variation could be reduced by using similar corrections for changing parameters in the reaction cells over time. The comparison of experimental setups and procedures as well as of data corrections identified potential improvements for future gas-fluid-rock studies
Accommodating heterogeneous missing data patterns for prostate cancer risk prediction
Objective: We compared six commonly used logistic regression methods for
accommodating missing risk factor data from multiple heterogeneous cohorts, in
which some cohorts do not collect some risk factors at all, and developed an
online risk prediction tool that accommodates missing risk factors from the
end-user. Study Design and Setting: Ten North American and European cohorts
from the Prostate Biopsy Collaborative Group (PBCG) were used for fitting a
risk prediction tool for clinically significant prostate cancer, defined as
Gleason grade group greater or equal 2 on standard TRUS prostate biopsy. One
large European PBCG cohort was withheld for external validation, where
calibration-in-the-large (CIL), calibration curves, and
area-underneath-the-receiver-operating characteristic curve (AUC) were
evaluated. Ten-fold leave-one-cohort-internal validation further validated the
optimal missing data approach. Results: Among 12,703 biopsies from 10 training
cohorts, 3,597 (28%) had clinically significant prostate cancer, compared to
1,757 of 5,540 (32%) in the external validation cohort. In external validation,
the available cases method that pooled individual patient data containing all
risk factors input by an end-user had best CIL, under-predicting risks as
percentages by 2.9% on average, and obtained an AUC of 75.7%. Imputation had
the worst CIL (-13.3%). The available cases method was further validated as
optimal in internal cross-validation and thus used for development of an online
risk tool. For end-users of the risk tool, two risk factors were mandatory:
serum prostate-specific antigen (PSA) and age, and ten were optional: digital
rectal exam, prostate volume, prior negative biopsy,
5-alpha-reductase-inhibitor use, prior PSA screen, African ancestry, Hispanic
ethnicity, first-degree prostate-, breast-, and second-degree prostate-cancer
family history
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