115 research outputs found
Resistance effects due to magnetic guiding orbits
The Hall and magnetoresistance of a two dimensional electron gas subjected to
a magnetic field barrier parallel to the current direction is studied as
function of the applied perpendicular magnetic field. The recent experimental
results of Nogaret {\em et al.} [Phys. Rev. Lett. {\bf 84}, 2231 (2000)] for
the magneto- and Hall resistance are explained using a semi-classical theory
based on the Landauer-B\"{u}ttiker formula. The observed positive
magnetoresistance peak is explained as due to a competition between a decrease
of the number of conducting channels as a result of the growing magnetic field,
from the fringe field of the ferromagnetic stripe as it becomes magnetized, and
the disappearance of snake orbits and the subsequent appearance of cycloidlike
orbits.Comment: 7 pages, 7 figure
Diagnostic criteria for cancer cachexia: Reduced food intake and inflammation predict weight loss and survival in an international, multi-cohort analysis
Abstract Background Cancerâassociated weight loss (WL) associates with increased mortality. International consensus suggests that WL is driven by a variable combination of reduced food intake and/or altered metabolism, the latter often represented by the inflammatory biomarker Câreactive protein (CRP). We aggregated data from Canadian and European research studies to evaluate the associations of reduced food intake and CRP with cancerâassociated WL (primary endpoint) and overall survival (OS, secondary endpoint). Methods The data set included a total of 12,253 patients at risk for cancerâassociated WL. Patientâreported WL history (% in 6 months) and food intake (normal, moderately, or severely reduced) were measured in all patients; CRP (mg/L) and OS were measured in N = 4960 and N = 9952 patients, respectively. All measures were from a baseline assessment. Clinical variables potentially associated with WL and overall survival (OS) including age, sex, cancer diagnosis, disease stage, and performance status were evaluated using multinomial logistic regression MLR and Cox proportional hazards models, respectively. Results Patients had a mean weight change of â7.3% (±7.1), which was categorized as: ±2.4% (stable weight; 30.4%), 2.5â5.9% (19.7%), 6.0â10.0% (23.2%), 11.0â14.9% (12.0%), â„15.0% (14.6%). Normal food intake, moderately, and severely reduced food intake occurred in 37.9%, 42.8%, and 19.4%, respectively. In MLR, severe WL (â„15%) (vs. stable weight) was more likely (P  100 mg/L: OR 2.30 (95% CI 1.62â3.26)]. Diagnosis, stage, and performance status, but not age or sex, were significantly associated with WL. Median OS was 9.9 months (95% CI 9.5â10.3), with median followâup of 39.7 months (95% CI 38.8â40.6). Moderately and severely reduced food intake and CRP independently predicted OS (P < 0.0001). Conclusions Modelling WL as the dependent variable is an approach that can help to identify clinical features and biomarkers associated with WL. Here, we identify criterion values for food intake impairment and CRP that may improve the diagnosis and classification of cancerâassociated cachexia
36. A prospective, randomized study to compare the value of two fractionation schemes of palliative radiotherapy for inoperable non-small cell lung cancer
A prospective, randomized study was conducted in eight Polish institutions to compare the value of two fractionation schemes of palliative radiotherapy for inoperable non-small cell lung cancer. Assessed was the impact of either treatment on the degree and duration of relief of tumor-related symptoms and on patient's performance status. Secondary endpoints included treatment side-effects, objective response and overall survival. One hundred patients were randomly assigned to the dose of 20 Gy/5Ă/5 days (Arm A) or 16 Gy/2Ă/8 days (Arm B). There were 90 men and 10 women aged between 47 and 79 (mean 66). Eighty four patients had locally advanced tumor and 16 patients had metastatic disease. Squamous cell carcinoma was diagnosed in 65 patients, adenocarcinoma â in 9 patients, large cell carcinoma â in 1 patient and unspecified non-small cell carcinoma â in 25 patients. Fifty five patients were assigned to Arm A and 45 â to Arm B. Ninety eight patients received assigned treatment whereas two patients died before the end of treatment. The final results of the study will be presented at the conference
A cost-effectiveness analysis of a preventive exercise program for patients with advanced head and neck cancer treated with concomitant chemo-radiotherapy
In recent years, concomitant chemo-radiotherapy (CCRT) has become an indispensable organ preserving treatment modality for advanced head and neck cancer, improving local control and overall survival in several anatomical sites [1]. Unfortunately, CCRT can have a detrimental effect on many functions of the upper respiratory and digestive system. Sequellae such as pain, oedema, xerostomia and fibrosis negatively affect mouth opening (trismus), chewing, swallowing and speech [1]. Several studies investigating long-term effects of CCRT have concluded that swallowing and nutritional dysfunction tend to be persistent and can be severe [2-4]. Not surprisingly, therefore, CCRT can have a negative effect on patientsâ quality of life (QoL) [2]. Moreover, even before onset of treatment patients may already present with pain, impaired swallowing, trismus, aspiration, dietary restrictions and tube dependency, and loss of body weight, because the tumour may disrupt the normal anatomy and thus interfere with normal function [1]. Many studies refer to the importance of rehabilitation after, and even during treatment, in order to support and improve those functions [2]. However, as yet, few studies have investigated the effects of (preventive) rehabilitation exercises on the predictable and inevitable swallowing and mouth opening problems for this patient group. In addition, little is known about the costs and benefits of such exercise programs for head and neck cancer. As the clinical effectiveness is established [4], it is now relevant to embark on cost-effectiveness as a contribution to decision making on coverage. The aim of this study was to analyze the incremental cost-effectiveness for a preventive exercise program (PREP) versus usual care (UC) for patients with advanced head and neck cancer treated at the Netherlands Cancer Institute - Antoni van Leeuwenhoek Hospital (NKI-AVL)
Malnutrition in patients treated for oral or oropharyngeal cancerâprevalence and relationship with oral symptoms: an explorative study
This study aimed to assess prevalence of malnutrition after treatment for oral/oropharyngeal cancer and to explore how oral symptoms relate to malnutrition after treatment. In this cross-sectional study, malnutrition (weight loss a parts per thousand yenaEuro parts per thousand 10% in 6 months or a parts per thousand yen5% in 1 month), oral symptoms (EORTC QLQ-H&N35 questionnaire and additional questions to assess chewing problems), dental status, trismus and dietary intake were assessed in 116 adult patients treated for oral/oropharyngeal cancer. Prevalence of malnutrition was 16% (95%CI: 10% to 23%). Prevalence of malnutrition in the period 0-3 months after treatment was significantly higher (25%) than in the periods > 3-12 months (13%) and > 12-36 months after treatment (3%, p = 0.008). Logistic multivariate regression analysis revealed that swallowing problems (p = 0.021) and insufficient protein intake were significantly related to malnutrition (p = 0.016). In conclusion, malnutrition is a considerable problem in patients treated for oral/oropharyngeal cancer, shortly after treatment. Of all oral symptoms, only swallowing problems were significantly related to malnutrition in the period after treatment for oral/oropharyngeal cancer
DoĆwiadczalna i numeryczna analiza niezatopionego wypĆywu spod zasuwy
The problem of sluice gate flow is analyzed using
two models: a simplified one, derived according
to the concept of the Potential Field (PF), and
a more complex form, based on the Reynolds
Average Navier-Stokes (RANS) equations. The
numerical solution is compared with experimental
data, including measurements performed by
authors and results acquired from literature. Despite
its simplicity, the PF model provides a satisfactory
agreement with the measurements. The
slightly worse performance of the RANS model
comes from an overestimation of energy losses.Niezatopiony
wypĆyw wody spod zasuwy opisano
dwoma modelami: uproszczonym, wyprowadzonym
na podstawie teorii pĆaskiego przepĆywu potencjalnego
(PF), i modelem o wiÄkszym stopniu
zĆoĆŒonoĆci, bazujÄ
cym na uĆrednieniu Reynoldsa
rĂłwnaĆ Naviera-Stokesa (RANS). Wyniki obliczeĆ
przepustowoĆci scharakteryzowano wspĂłĆczynnikami
wydatku i porĂłwnano z wynikami
wĆasnych pomiarĂłw hydraulicznych oraz podawanymi
w literaturze. WspĂłĆczynniki wydatku
uzyskane z modelu PF sÄ
zbliĆŒone do wynikĂłw
badaĆ eksperymentalnych. Nieco wiÄksze rĂłĆŒnice
wartoĆci wspĂłĆczynnikĂłw wydatku uzyskano
z obliczeĆ modelem RANS. Wynika to z przeszacowania
strat energii strumienia wody
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