2,954 research outputs found
The Parton Structure of the Nucleon and Precision Determination of the Weinberg Angle in Neutrino Scattering
A recently completed next-to-leading-order program to calculate neutrino
cross sections, including power-suppressed mass correction terms, has been
applied to evaluate the Paschos-Wolfenstein relation, in order to
quantitatively assess the validity and significance of the NuTeV anomaly. In
particular, we study the shift of obtained in
calculations with a new generation of PDF sets that allow , enabled by recent neutrino dimuon data from CCFR and NuTeV, as
compared to the previous parton distribution functions like
CTEQ6M. The extracted value of is closely
correlated with the strangeness asymmetry momentum integral
. We also consider isospin violating effects
that have recently been explored by the MRST group. The results of our study
suggest that the new dimuon data, the Weinberg angle measurement, and other
data sets used in global QCD parton structure analysis can all be consistent
within the Standard Model.Comment: 4 page
Time-lapse monitoring of root water uptake using electrical resistivity tomography and mise-Ă -la-masse: a vineyard infiltration experiment
Abstract. This paper presents a time-lapse application of
electrical methods (electrical resistivity tomography, ERT; and
mise-Ă -la-masse, MALM) for monitoring plant roots and their activity
(root water uptake) during a controlled infiltration experiment. The use of
non-invasive geophysical monitoring is of increasing interest as these
techniques provide time-lapse imaging of processes that otherwise can only
be measured at few specific spatial locations. The experiment here described was conducted in a vineyard in Bordeaux (France) and was focused on the
behaviour of two neighbouring grapevines. The joint application of ERT and
MALM has several advantages. While ERT in time-lapse mode is sensitive to
changes in soil electrical resistivity and thus to the factors controlling
it (mainly soil water content, in this context), MALM uses DC current
injected into a tree stem to image where the plant root system is in effective
electrical contact with the soil at locations that are likely to be the same
where root water uptake (RWU) takes place. Thus, ERT and MALM provide
complementary information about the root structure and activity. The
experiment shows that the region of likely electrical current sources
produced by MALM does not change significantly during the infiltration time
in spite of the strong changes of electrical resistivity caused by changes
in soil water content. Ultimately, the interpretation of the current source
distribution strengthened the hypothesis of using current as a proxy for
root detection. This fact, together with the evidence that current injection
in the soil and in the stem produces totally different voltage patterns,
corroborates the idea that this application of MALM highlights the active
root density in the soil. When considering the electrical resistivity
changes (as measured by ERT) inside the stationary volume of active roots
delineated by MALM, the overall tendency is towards a resistivity increase
during irrigation time, which can be linked to a decrease in soil water
content caused by root water uptake. On the contrary, when considering the
soil volume outside the MALM-derived root water uptake region, the
electrical resistivity tends to decrease as an effect of soil water content
increase caused by the infiltration. The use of a simplified infiltration
model confirms at least qualitatively this behaviour. The monitoring results
are particularly promising, and the method can be applied to a variety of
scales including the laboratory scale where direct evidence of root
structure and root water uptake can help corroborate the approach. Once
fully validated, the joint use of MALM and ERT can be used as a valuable
tool to study the activity of roots under a wide variety of field
conditions
Survey of hepatitis B knowledge and stigma among chronically infected patients and uninfected persons in Beijing, China
Background & AimsHepatitis B virus (HBV) infection carries substantial stigma in China. We surveyed HBV knowledge and stigma among chronic hepatitis B (CHB) patients and persons without HBV infection in Beijing, China.MethodsFour hundred and thirty five CHB patients and 801 controls at Peking University Peopleâs Hospital were surveyed.ResultsChronic hepatitis B patients were older (mean 46 vs. 39 years) and more often men (71 vs. 48%) than controls. Mean knowledge score was 11.9/15 for CHB and 9.3/15 for control patients (P < 0.001). Average stigma score was 22.1/39 for CHB and 19.2/30 for control patients. Controls expressed discomfort with close contact (45%) or sharing meals with CHB patients (39%) and believed CHB patients should not be allowed to work in restaurants (58%) or childcare (44%). Chronic hepatitis B patients felt that they were undesirable as spouses (33 vs. 17%) and brought trouble to their families (58 vs. 34%) more often than controls. Despite legal prohibitions, 40% of CHB patients were required to undergo preâemployment HBV testing, and 29% of these individuals thought that they lost job opportunities because of their disease status. 16% of CHB patients regretted disclosing their HBV status and disclosure was inversely associated with stigma. Higher stigma was associated with older age, lower education and lower knowledge score among controls; and with lower education, younger age, having undergone preâemployment HBV testing and regret disclosing their HBV status among CHB patients.ConclusionDespite high prevalence of CHB in China, our study shows knowledge is limited and there is significant societal and internalized stigma associated with HBV infection.See Editorial on Page 1582Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134440/1/liv13168_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134440/2/liv13168.pd
Type and dose of radiotherapy used for initial treatment of non-metastatic prostate cancer
BACKGROUND: We sought to describe patterns of initial radiotherapy among non-metastatic prostate cancer (PC) patients by recurrence risk groups.
METHODS: Medical records were abstracted for a sample of 9017 PC cases diagnosed in 2004 as a part of the Center for Disease Control and Prevention\u27s Prostate and Breast Patterns of Care Study in seven states. Non-metastatic PC cases are categorized as low-risk (LR), intermediate-risk (IR) or high-risk (HR) groups based on pretreatment PSA, tumor stage, and Gleason score per 2002 NCCN guidelines. Univariate and multivariate analyses were employed to determine factors associated with the type and dose of radiotherapy by the risk groups.
RESULTS: Of the 9,017 patients, 3153 who received definitive radiotherapy either alone or in combination with hormone therapy (HT) were selected for in-depth analysis. Multivariate models showed that LR patients were more likely to receive seed implant brachytherapy (BT) than those in higher risk groups. Those in the IR group were most likely to receive external beam radiotherapy (EBRT) combined with BT or high-dose radiotherapy. Use of HT in combination with radiotherapy was more common in the IR and HR groups than for LR patients. Intensity modulated radiation treatment (IMRT) was used to treat 32.6% of PC patients treated with EBRT, with the majority (60.6%) treated with high-dose radiotherapy.
CONCLUSIONS: Radiotherapy types and dosage utilization varied by PC risk groups. Patients in IR were more likely than those in LR or HR to receive high-dose radiotherapy. IMRT was used in about one third of patients to deliver high-dose radiotherapy
Properties of a Fetal Multipotent Neural Stem Cell (NEP Cell)
AbstractMultipotent neural stem cells (NSCs) present in the developing neural tube (E10.5, neuroepithelial cells; NEP) were examined for the expression of candidate stem cell markers, and the expression of these markers was compared with later appearing precursor cells (E14.5) that can be distinguished by the expression of embryonic neural cell adhesion molecule (E-NCAM) and A2B5. NEP cells possess gap junctions, express connexins, and appear to lack long cilia. Most candidate markers, including Nestin, Presenilin, Notch, and Numb, were expressed by both NEP cells as well as other cell populations. Fibroblast growth factor receptor 4 (FGFR4), Frizzled 9 (Fz9), and SRY box-containing gene 2 (Sox2) as assessed by immunocytochemistry and in situ hybridization are markers that appear to distinguish NSCs from other precursor cells. Neither Hoechst 33342 nor rhodamine-123 staining, telomerase (Tert) expression, telomerase activity, or breakpoint cluster region protein 1 (Bcrp1) transporter expression could be used to distinguish NEP stem cells from other dividing cells. NEP cells, however, lacked expression of several lineage markers that are expressed by later appearing cells. These included absence of expression of CD44, E-NCAM, A2B5, epidermal growth factor receptor (EGFR), and platelet-derived growth factor receptor-alpha (PDGFRα), suggesting that negative selection using cell surface epitopes could be used to isolate stem cell populations from mixed cultures of cells. Using mixed cultures of cells isolated from E14.5 stage embryos, we show that NEP cells can be enriched by depleting differentiating cells that express E-NCAM or A2B5 immunoreactivity. Overall, our results show that a spectrum of markers used in combination can reliably distinguish multipotent NSCs from other precursor cells as well as differentiated cells present in the CNS
A Review of Target Mass Corrections
With recent advances in the precision of inclusive lepton--nuclear scattering
experiments, it has become apparent that comparable improvements are needed in
the accuracy of the theoretical analysis tools. In particular, when extracting
parton distribution functions in the large-x region, it is crucial to correct
the data for effects associated with the nonzero mass of the target. We present
here a comprehensive review of these target mass corrections (TMC) to structure
functions data, summarizing the relevant formulas for TMCs in electromagnetic
and weak processes. We include a full analysis of both hadronic and partonic
masses, and trace how these effects appear in the operator product expansion
and the factorized parton model formalism, as well as their limitations when
applied to data in the x->1 limit. We evaluate the numerical effects of TMCs on
various structure functions, and compare fits to data with and without these
corrections.Comment: 41 pages, 13 figures; minor updates to match published versio
Pharmacogenetic testing affects choice of therapy among women considering tamoxifen treatment
Abstract Background Pharmacogenetic testing holds major promise in allowing physicians to tailor therapy to patients based on genotype. However, there is little data on the impact of pharmacogenetic test results on patient and clinician choice of therapy. CYP2D6 testing among tamoxifen users offers a potential test case of the use of pharmacogenetic testing in the clinic. We evaluated the effect of CYP2D6 testing in clinical practice to determine whether genotype results affected choice of hormone therapy in a prospective cohort study. Methods Women planning to take or currently taking tamoxifen were considered eligible. Participants were enrolled in an informational session that reviewed the results of studies of CYP2D6 genotype on breast cancer recurrence. CYP2D6 genotyping was offered to participants using the AmpliChip CYP450 Test. Women were classified as either poor, intermediate, extensive or ultra-rapid metabolizers. Results were provided to clinicians without specific treatment recommendations. Follow-up was performed with a structured phone interview 3 to 6 months after testing to evaluate changes in medication. Results A total of 245 women were tested and 235 completed the follow-up survey. Six of 13 (46%) women classified as poor metabolizers reported changing treatment compared with 11 of 218 (5%) classified as intermediate, extensive or ultra-rapid metabolizers (P < 0.001). There was no difference in treatment choices between women classified as intermediate and extensive metabolizers. In multi-variate models that adjusted for age, race/ethnicity, educational status, method of referral into the study, prior knowledge of CYP2D6 testing, the patients' CYP2D6 genotype was the only significant factor that predicted a change in therapy (odds ratio 22.8; 95% confidence interval 5.2 to 98.8). Genetic testing did not affect use of co-medications that interact with CYP2D6. Conclusions CYP2D6 genotype testing led to changes in therapy among poor metabolizers, even in the absence of definitive data that an alternative medicine improved outcomes. Pharmacogenetic testing can affect choice of therapy, even in the absence of definitive data on clinical impact
Performance of ICDâ10âCM diagnosis codes for identifying children with Sickle Cell Anemia
ObjectiveTo develop, test, and validate the performance of ICDâ10âCM claimsâbased case definitions for identifying children with sickle cell anemia (SCA).Data SourcesMedicaid administrative claims (2016) for children <18 years with potential SCA (any D57x diagnosis code) and newborn screening records from Michigan and New York State.Study DesignThis study is a secondary data analysis.Data Collection/Extraction MethodsUsing specific SCAârelated (D5700, D5701, and D5702) and nonspecific (D571) diagnosis codes, 23 SCA case definitions were applied to Michigan Medicaid claims (2016) to identify children with SCA. Measures of performance (sensitivity, specificity, area under the ROC curve) were calculated using newborn screening results as the gold standard. A parallel analysis was conducted using New York State Medicaid claims and newborn screening data.Principal FindingsIn Michigan Medicaid, 1597 children had â„1 D57x claim; 280 (18 percent) were diagnosed with SCA. Measures of performance varied, with sensitivities from 0.02 to 0.97 and specificities from 0.88 to 1.0. The case definition of â„1 outpatient visit with a SCAârelated or D571 code had the highest area under the ROC curve, with a sensitivity of 95 percent and specificity of 92 percent. The same definition also had the highest performance in New York Medicaid (n = 2454), with a sensitivity of 94 percent and specificity of 86 percent.ConclusionsChildren with SCA can be accurately identified in administrative claims using this straightforward case definition. This methodology can be used to monitor trends and use of health services after transition to ICDâ10âCM.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154614/1/hesr13257.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154614/2/hesr13257_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154614/3/hesr13257-sup-0001-Authormatrix.pd
Small-scale characterization of vine plant root water uptake via 3-D electrical resistivity tomography and mise-Ă -la-masse method
The investigation of plant roots is inherently difficult and often neglected.
Being out of sight, roots are often out of mind. Nevertheless, roots play a key role
in the exchange of mass and energy between soil and the atmosphere, in addition to
the many practical applications in agriculture. In this paper, we propose a
method for roots imaging based on the joint use of two electrical
noninvasive methods: electrical resistivity tomography (ERT) and
mise-Ă -la-masse (MALM). The approach is based on the key assumption that the
plant root system acts as an electrically conductive body, so that injecting
electrical current into the plant stem will ultimately result in the injection
of current into the subsoil through the root system, and particularly through
the root terminations via hair roots. Evidence from field data, showing that
voltage distribution is very different whether current is injected into the
tree stem or in the ground, strongly supports this hypothesis. The proposed
procedure involves a stepwise inversion of both ERT and MALM data that
ultimately leads to the identification of electrical resistivity (ER)
distribution and of the current injection root distribution in the
three-dimensional soil space. This, in turn, is a proxy to the active (hair)
root density in the ground. We tested the proposed procedure on synthetic
data and, more importantly, on field data collected in a vineyard, where the
estimated depth of the root zone proved to be in agreement with literature on
similar crops. The proposed noninvasive approach is a step forward towards a
better quantification of root structure and functioning.</p
- âŠ