2,008 research outputs found
A systematic review of the nutritional consequences of esophagectomy
Background & aims
As improved outcomes after esophagectomy have been observed over the last two decades, the focus on care has shifted to survivorship and quality of life. The aim of this review was to determine changes in nutrition after esophagectomy and to assess the evidence for extended nutrition support.
Methods
A search strategy was developed to identify primary research reporting change in nutritional status a minimum of one month after esophagectomy.
Results
Changes in nutritional parameters reported by 18 studies indicated a weight loss of 5â12% at six months postoperatively. More than half of patients lost >10% of body weight at 12 months. One study reported a persistent weight loss of 14% from baseline three years after surgery. Three studies reporting on longer term follow up noted that 27%â95% of patients failed to regain their baseline weight. Changes in dietary intake (three studies) indicated inadequate energy and protein intake up to three years after surgery. Global quality of life scores reported in one study correlated with better weight preservation. There were a high frequency of gastrointestinal symptoms reported in six studies, most notably in the first year after surgery, but persisting up to 19 years. Extended enteral nutrition on a selective basis has been reported in several studies.
Conclusions
Nutritional status is compromised in the months/years following oesophagectomy and may never return to baseline levels. The causes/consequences of weight loss/impaired nutritional intake require further investigation. The role of extended nutritional support in this population remains unclear
Evaluating the correspondence between face-, scene-, and object-selectivity and retinotopic organization within lateral occipitotemporal cortex
Tracing groundwater flow and sources of organic carbon in sandstone aquifers using fluorescence properties of dissolved organic matter (DOM)
The fluorescence properties of groundwaters from sites in two UK aquifers, the Penrith Sandstone of Cumbria and the Sherwood Sandstone of South Yorkshire, were investigated using excitation-emission matrix (EEM) fluorescence spectroscopy. Both aquifers are regionally important sources of public supply water and are locally impacted by anthropogenic pollution. The Penrith Sandstone site is in a rural setting while the Sherwood Sandstone site is in suburban Doncaster. Fluorescence analysis of samples from discrete sample depths in the Penrith Sandstone shows decreasing fulvic-like intensities with depth and also shows a good correlation with CFC-12, an anthropogenic groundwater tracer. Tryptophan- like fluorescence centres in the depth profile may also provide evidence of rapid routing of relatively recent applications of organic slurry along fractures. Fluorescence analysis of groundwater sampled from multi-level piezometers installed within the Sherwood Sandstone aquifer also shows regions of tryptophan-like and relatively higher fulvic-like signatures. The fluorescence intensity profile in the piezometers shows tryptophan-like peaks at depths in excess of 50 metres and mirrors the pattern exhibited by microbial species and CFCs highlighting the deep and rapid penetration of modern recharge due to rapid fracture flow. Fluorescence analysis has allowed the rapid assessment of different types and relative abundances of dissolved organic matter (DOM), and the fingerprinting of different sources of organic carbon within the groundwater system. The tryptophan:fulvic ratios found in the Penrith Sandstone were found to be between (0.5â3.0) and are characteristic of ratios from sheep waste sources. The Sherwood Sandstone has the lowest ratios (0.2â0.4) indicating a different source of DOM, most likely a mixture of terrestrial and microbial sources, although there is little evidence of pollution from leaking urban sewage systems. Results from these two studies suggest that intrinsic fluorescence may be used as a proxy for, or complimentary tool to, other groundwater investigation methods in helping provide a conceptual model of groundwater flow and identifying different sources of DOM within the groundwater system
Global patterns in the divergence between phylogenetic diversity and species richness in terrestrial birds
Aim The conservation value of sites is often based on species richness (SR).However, metrics of phylogenetic diversity (PD) reïŹect a communityâs evolu-tionary potential and reveal the potential for additional conservation valueabove that based purely on SR. Although PD is typically correlated with SR,localized differences in this relationship have been found in different taxa.Here, we explore geographical variation in global avian PD. We identify wherePD is higher or lower than expected (from SR) and explore correlates of thosedifferences, to ïŹnd communities with high irreplaceability, in terms of theuniqueness of evolutionary histories.Location Global terrestrial.Methods Using comprehensive avian phylogenies and global distributionaldata for all extant birds, we calculated SR and Faithâs PD, a widely appliedmeasure of community PD, across the terrestrial world. We modelled the rela-tionship between avian PD for terrestrial birds and its potential environmentalcorrelates. Analyses were conducted at a global scale and also for individualbiogeographical realms. Potential explanatory variables of PD included SR,long-term climate stability, climatic diversity (using altitudinal range as aproxy), habitat diversity and proximity to neighbouring realms.Results We identiïŹed areas of high and low relative PD (rPD; PD relative tothat expected given SR). Areas of high rPD were associated with deserts andislands, while areas of low rPD were associated with historical glaciation. Ourresults suggest that rPD is correlated with different environmental variables indifferent parts of the world.Main conclusions There is geographical variation in avian rPD, much ofwhich can be explained by putative drivers. However, the importance of thesedrivers shows pronounced regional variation. Moreover, the variation in avianrPD differs substantially from patterns found for mammals and amphibians.We suggest that PD adds additional insights about the irreplaceability of com-munities to conventional metrics of biodiversity based on SR, and could beusefully included in assessments of site valuation and prioritizatio
Almost sure exponential stability of numerical solutions for stochastic delay differential equations
Using techniques based on the continuous and discrete semimartingale convergence theorems, this paper investigates if numerical methods may reproduce the almost sure exponential stability of the exact solutions to stochastic delay differential equations (SDDEs). The important feature of this technique is that it enables us to study the almost sure exponential stability of numerical solutions of SDDEs directly. This is significantly different from most traditional methods by which the almost sure exponential stability is derived from the moment stability by the Chebyshev inequality and the BorelâCantelli lemma
Scaling functions for O(4) in three dimensions
Monte Carlo simulation using a cluster algorithm is used to compute the
scaling part of the free energy for a three dimensional O(4) spin model. The
results are relevant for analysis of lattice studies of high temperature QCD.Comment: 12 pages, 6 figures, uses epsf.st
Subsoiling and surface tillage effects on soil physical properties and forage oat stand and yield
Much of New Zealand's agriculture integrates animal and crop production on poorly drained,
easily compacted soils. We hypothesized that soil properties affecting forage oat (Avena sativa,
cv Awapuni) establishment on land compacted by 15 years of conventional cropping might be
influenced by various subsoiling and surface tillage combinations. Plots on a Moutoa silty clay
(Typic Haplaquoil) were paraplowed (P), deep subsoiled (V), shallow subsoiled (5), or were left
as non-subsoiled controls (C). Subsequently, the surface 15 cm was surface-tilled (T) using a
power rotary-tiller and firmed with a Cambridge roller or were not tilled (N). Oats were then sown
with a cross-slot drill. Subsoiling greatly reduced soil strength. Cone indices showed disruption to
40cm with P, 36 cm for V, and 30 cm for S. Approximately 60% of profile cone indices to a depth
of 0.5 m from subsoiled treatments were less than 1.5 MPa, compared to approximately 30% for C.
T slightly improved strength distribution in non-subsoiled controls but had little effect in subsoiled
treatments. Subsoiling without T continued to show improved profile cone index cumulative
frequency 233 days after subsoiling, Subsoiling after T in this high rainfall climate eliminated
most of the separation in cumulative frequency of soil profile cone index values by two weeks
after T. T reduced emergence from 142 to 113 plants per square meter and reduced yield from
5318 to 3679 kg ha-1. Forage yield increased from 3974 to 4674 kg ha-1 with subsoiling. Soil
porosity, saturated and slightly unsaturated hydraulic conductivities (KSAT and K_40 ) and air
permeability were highly variable but generally increased with subsoiling. Oxygen diffusion rate
(ODR) (using Pt microelectrodes) was also variable, but N and C treatments had consistently
lower ODRs than T or subsoiled treatments. Generally, subsoiling without T produced better soil
conditions and oat crop performance than the prevailing New Zealand practice of T without subsoiling
An integral method for solving nonlinear eigenvalue problems
We propose a numerical method for computing all eigenvalues (and the
corresponding eigenvectors) of a nonlinear holomorphic eigenvalue problem that
lie within a given contour in the complex plane. The method uses complex
integrals of the resolvent operator, applied to at least column vectors,
where is the number of eigenvalues inside the contour. The theorem of
Keldysh is employed to show that the original nonlinear eigenvalue problem
reduces to a linear eigenvalue problem of dimension .
No initial approximations of eigenvalues and eigenvectors are needed. The
method is particularly suitable for moderately large eigenvalue problems where
is much smaller than the matrix dimension. We also give an extension of the
method to the case where is larger than the matrix dimension. The
quadrature errors caused by the trapezoid sum are discussed for the case of
analytic closed contours. Using well known techniques it is shown that the
error decays exponentially with an exponent given by the product of the number
of quadrature points and the minimal distance of the eigenvalues to the
contour
Lysosomal and phagocytic activity is increased in astrocytes during disease progression in the SOD1 G93A mouse model of amyotrophic lateral sclerosis
Astrocytes are key players in the progression of amyotrophic lateral sclerosis (ALS). Previously, gene expression profiling of astrocytes from the pre-symptomatic stage of the SOD1G93A model of ALS has revealed reduced lactate metabolism and altered trophic support. Here, we have performed microarray analysis of symptomatic and late-stage disease astrocytes isolated by laser capture microdissection (LCM) from the lumbar spinal cord of the SOD1G93A mouse to complete the picture of astrocyte behavior throughout the disease course. Astrocytes at symptomatic and late-stage disease show a distinct up-regulation of transcripts defining a reactive phenotype, such as those involved in the lysosome and phagocytic pathways. Functional analysis of hexosaminidase B enzyme activity in the spinal cord and of astrocyte phagocytic ability has demonstrated a significant increase in lysosomal enzyme activity and phagocytic activity in SOD1G93A vs. littermate controls, validating the findings of the microarray study. In addition to the increased reactivity seen at both stages, astrocytes from late-stage disease showed decreased expression of many transcripts involved in cholesterol homeostasis. Staining for the master regulator of cholesterol synthesis, SREBP2, has revealed an increased localization to the cytoplasm of astrocytes and motor neurons in late-stage SOD1G93A spinal cord, indicating that down-regulation of transcripts may be due to an excess of cholesterol in the CNS during late-stage disease possibly due to phagocytosis of neuronal debris. Our data reveal that SOD1G93A astrocytes are characterized more by a loss of supportive function than a toxic phenotype during ALS disease progression and future studies should focus upon restorative therapies
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