323 research outputs found
Resectable Pancreatic Cancer: Is Surgery the Best First Step?
 Controversy exist regarding the potential benefit of the neoadjuvant approach to pancreatic cancer as limited retrospective data exists comparing pre- with post-operative chemoradiation. The optimal treatment approach remains unclear as we await prospective randomized clinical trials evaluating the hypothesized benefit of the neoadjuvant therapy for resectable pancreatic cancer and as there has been no proven survival benefit to date. Here we summarize the data presented at the 2012 American Society of Clinical Oncology (ASCO) Gastrointestinal Cancers Symposium providing additional insight into the potential of neoadjuvant therapy in the treatment of pancreatic cancer. (Abstracts #156, #162, #168 and #177).
Master singular behavior from correlation length measurements for seven one-component fluids near their gas-liquid critical point
We present the master (i.e. unique) behavior of the correlation length, as a
function of the thermal field along the critical isochore, asymptotically close
to the gas-liquid critical point of xenon, krypton, argon, helium 3, sulfur
hexafluoride, carbon dioxide and heavy water. It is remarkable that this
unicity extends to the correction-to-scaling terms. The critical parameter set
which contains all the needed information to reveal the master behavior, is
composed of four thermodynamic coordinates of the critical point and one
adjustable parameter which accounts for quantum effects in the helium 3 case.
We use a scale dilatation method applied to the relevant physical variables of
the onecomponent fluid subclass, in analogy with the basic hypothesis of the
renormalization theory. This master behavior for the correlation length
satisfies hyperscaling. We finally estimate the thermal field extent, where the
critical crossover of the singular thermodynamic and correlation functions
deviate from the theoretical crossover function obtained from field theory.Comment: Submitted to Physical Review
Comparison of the diagnostic accuracy of three current guidelines for the evaluation of asymptomatic pancreatic cystic neoplasms.
Asymptomatic pancreatic cysts are a common clinical problem but only a minority of these cases progress to cancer. Our aim was to compare the accuracy to detect malignancy of the 2015 American Gastroenterological Association (AGA), the 2012 International Consensus/Fukuoka (Fukuoka guidelines [FG]), and the 2010 American College of Radiology (ACR) guidelines.We conducted a retrospective study at 3 referral centers for all patients who underwent resection for an asymptomatic pancreatic cyst between January 2008 and December 2013. We compared the accuracy of 3 guidelines in predicting high-grade dysplasia (HGD) or cancer in resected cysts. We performed logistic regression analyses to examine the association between cyst features and risk of HGD or cancer.A total of 269 patients met inclusion criteria. A total of 228 (84.8%) had a benign diagnosis or low-grade dysplasia on surgical pathology, and 41 patients (15.2%) had either HGD (n = 14) or invasive cancer (n = 27). Of the 41 patients with HGD or cancer on resection, only 3 patients would have met the AGA guideline\u27s indications for resection based on the preoperative cyst characteristics, whereas 30/41 patients would have met the FG criteria for resection and 22/41 patients met the ACR criteria. The sensitivity, specificity, positive predictive value, negative predictive value of HGD, and/or cancer of the AGA guidelines were 7.3%, 88.2%, 10%, and 84.1%, compared to 73.2%, 45.6%, 19.5%, and 90.4% for the FG and 53.7%, 61%, 19.8%, and 88% for the ACR guidelines. In multivariable analysis, cyst size \u3e3 cm, compared to ≤3 cm, (odds ratio [OR] = 2.08, 95% confidence interval [CI] = 1.11, 4.2) and each year increase in age (OR = 1.07, 95% CI = 1.03, 1.11) were positively associated with risk of HGD or cancer on resection.In patients with asymptomatic branch duct-intraductal papillary mucinous neoplasms or mucinous cystic neoplasms who underwent resection, the prevalence rate of HGD or cancer was 15.2%. Using the 2015 AGA criteria for resection would have missed 92.6% of patients with HGD or cancer. The more inclusive FG and ACR had a higher sensitivity for HGD or cancer but lower specificity. Given the current deficiencies of these guidelines, it will be important to determine the acceptable rate of false-positives in order to prevent a single true-positive
The LCLS-II Gun & Buncher LLRF Controller Upgrade
LCLS-II is currently in its commissioning phase at SLAC. It is an X-ray FEL
driven by a CW superconducting LINAC. The beam injector plays a crucial role in
the overall performance of the accelerator, and is critical to the final
electron beam performance parameters. The LCLS-II injector comprises of a 185.7
MHz VHF copper gun cavity, and a 1.3 GHz two-cell L-band copper buncher cavity.
The FPGA-based controller employs feedback and Self-Excited Loop logic in order
to regulate the cavity fields. It also features several other functionalities,
such as live detune computation, active frequency tracking, and waveform
recording. The LLRF system drives the cavities via two 60 kW SSAs through two
power couplers, and thus stabilizes the fields inside the plant. This paper
provides an outline of the general functionalities of the system, alongside a
description of its hardware, firmware and software architecture, before
finalizing with the current status of the project and its future goals.Comment: Poster presented at LLRF Workshop 2022 (LLRF2022, arXiv:2208.13680
Craters Hosting Radar-Bright Deposits in Mercury's North Polar Region: Areas of Persistent Shadow Determined from MESSENGER Images
Radar-bright features near Mercury's poles were discovered in Earth-based radar images and proposed to be water ice present in permanently shadowed areas. Images from MESSENGER's one-year primary orbital mission provide the first nearly complete view of Mercury’s north polar region, as well as multiple images of the surface under a range of illumination conditions. We find that radar-bright features near Mercury's north pole are associated with locations persistently shadowed in MESSENGER images. Within 10 degrees of the pole, almost all craters larger than 10 km in diameter host radar-bright deposits. There are several craters located near Mercury's north pole with sufficiently large diameters to enable long-lived water ice to be thermally stable at the surface within regions of permanent shadow. Craters located farther south also host radar-bright deposits and show a preference for cold-pole longitudes; thermal models suggest that a thin insulating layer is required to cover these deposits if the radar-bright material consists predominantly of longlived water ice. Many small (less than 10 km diameter) and low-latitude (extending southward to 66 degrees N) craters host radar-bright material, and water ice may not be thermally stable in these craters for ~1 Gy, even beneath an insulating layer. The correlation of radar-bright features with persistently shadowed areas is consistent with the deposits being composed of water ice, and future thermal modeling of small and low-latitude craters has the potential to further constrain the nature, source, and timing of emplacement of the radar-bright material
Placement decisions and disparities among Aboriginal groups: An application of the Decision Making Ecology through multi-level analysis
a b s t r a c t Objective: This paper examined the relative influence of clinical and organizational characteristics on the decision to place a child in out-of-home care at the conclusion of a child maltreatment investigation. It tested the hypothesis that extraneous factors, specifically, organizational characteristics, impact the decision to place a child in out-of-home care. A secondary aim was to identify possible decision making influences related to disparities in placement decisions tied to Aboriginal children. Research suggests that the Aboriginal status of the child and structural risk factors affecting the family, such as poverty and poor housing, substantially account for this overrepresentation. Methods: The decision to place a child in out-of-home care was examined using data from the Canadian Incidence Study of Reported Child Abuse and Neglect. This child welfare dataset collected information about the results of nearly 5,000 child maltreatment investigations as well as a description of the characteristics of the workers and organization responsible for conducting those investigations. Multi-level statistical models were developed using MPlus software, which can accommodate dichotomous outcome variables, which are more reflective of decision making in child welfare. Mplus allows the specific case of the logistic link function for binary outcome variables under maximum likelihood estimation. Results: Final models revealed the importance of the number of Aboriginal reports to an organization as a key second level predictor of the placement decision. It is the only second level factor that remains in the final model. This finding was very stable when tested over several different levels of proportionate caseload representation ranging from greater than 50% to 20% of the caseload. Conclusions: Disparities among Aboriginal children in child welfare decision making were identified at the agency level. Practice implications: The study provides additional evidence supporting the possibility that one source of overrepresentation of Aboriginal children in the Canadian foster care system is a lack of appropriate resources at the agency or community level
Station report on the Goddard Space Flight Center (GSFC) 1.2 meter telescope facility
The 1.2 meter telescope system was built for the Goddard Space Flight Center (GSFC) in 1973-74 by the Kollmorgen Corporation as a highly accurate tracking telescope. The telescope is an azimuth-elevation mounted six mirror Coude system. The facility has been used for a wide range of experimentation including helioseismology, two color refractometry, lunar laser ranging, satellite laser ranging, visual tracking of rocket launches, and most recently satellite and aircraft streak camera work. The telescope is a multi-user facility housed in a two story dome with the telescope located on the second floor above the experimenter's area. Up to six experiments can be accommodated at a given time, with actual use of the telescope being determined by the location of the final Coude mirror. The telescope facility is currently one of the primary test sites for the Crustal Dynamics Network's new UNIX based telescope controller software, and is also the site of the joint Crustal Dynamics Project / Photonics Branch two color research into atmospheric refraction
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