938 research outputs found
A preliminary evaluation of LANDSAT-4 thematic mapper data for their geometric and radiometric accuracies
Some LANDSAT thematic mapper data collected over the eastern United States were analyzed for their whole scene geometric accuracy, band to band registration and radiometric accuracy. Band ratio images were created for a part of one scene in order to assess the capability of mapping geologic units with contrasting spectral properties. Systematic errors were found in the geometric accuracy of whole scenes, part of which were attributable to the film writing device used to record the images to film. Band to band registration showed that bands 1 through 4 were registered to within one pixel. Likewise, bands 5 and 7 also were registered to within one pixel. However, bands 5 and 7 were misregistered with bands 1 through 4 by 1 to 2 pixels. Band 6 was misregistered by 4 pixels to bands 1 through 4. Radiometric analysis indicated two kinds of banding, a modulo-16 stripping and an alternate light dark group of 16 scanlines. A color ratio composite image consisting of TM band ratios 3/4, 5/2, and 5/7 showed limonitic clay rich soils, limonitic clay poor soils, and nonlimonitic materials as distinctly different colors on the image
Fermion masses and mixings in gauge theories
The recent evidence for neutrino oscillations stimulate us to discuss again
the problem of fermion masses and mixings in gauge theories. In the standard
model, several forms for quark mass matrices are equivalent. They become
ansatze within most extensions of the standard model, where also relations
between quark and lepton sectors may hold. In a seesaw framework, these
relations can constrain the scale of heavy neutrino mass, which is often
related to the scale of intermediate or unification gauge symmetry. As a
consequence, two main scenarios arise. Hierarchies of masses and mixings may be
explained by broken horizontal symmetries.Comment: 25 pages, RevTex, no figures. Few misprints corrected and two
references adde
Treatment with Antiangiogenic Drugs in Multiple Lines in Patients with Metastatic Colorectal Cancer: Meta-Analysis of Randomized Trials
Background. In metastatic colorectal cancer (mCRC), continuing antiangiogenic drugs beyond progression might provide clinical benefit. We synthesized the available evidence in a meta-analysis. Patients and Methods. We conducted a meta-analysis of studies investigating the use of antiangiogenic drugs beyond progression. Eligible studies were randomized phase II/III trials. Primary endpoints were overall survival (OS) and progression-free survival (PFS). Secondary endpoints were the impact of continuing antiangiogenic drugs (i) in subgroups, (ii) in different types of compounds targeting the VEGF-axis (monoclonal antibodies versus tyrosine kinase inhibitors), and (iii) on remission rates and prevention of progression. Results. Eight studies (3,668 patients) were included. Continuing antiangiogenic treatment beyond progression significantly improved PFS (HR 0.64; 95%-CI, 0.55-0.75) and OS (HR 0.83; 95%-CI, 0.76-0.89). PFS was significantly improved in all subgroups with comparable HR. OS was improved in all subgroups stratified by age, gender, and ECOG status. The rate of patients achieving at least stable disease was improved with an OR of 2.25 (95%-CI, 1.41-3.58). Conclusions. This analysis shows a significant PFS and OS benefit as well as a benefit regarding disease stabilization when using antiangiogenic drugs beyond progression in mCRC. Future studies should focus on the optimal sequence of administering antiangiogenic drugs
Bloodstream infections in patients with rectal colonization by Klebsiella pneumoniae producing different type of carbapenemases: a prospective, cohort study
Objective: To investigate the hypothesis that intestinal colonization by different types of carbapenemase-resistant Klebsiella pneumoniae (CR-Kp) leads to different risks for bloodstream infections (BSI) caused by the same colonizing organism.
Methods: Prospective observational study including consecutive CR-Kp rectal carriers admitted to the Pisa University Hospital (December 2018 to December 2019). Patients underwent rectal swabbing with molecular testing for the different carbapenemases at hospital admission and during hospitalization. Rectal carriers were classified as: NDM, KPC, VIM and OXA-48. The primary end point was the rate of BSI by the same colonizing organism in each study group. A multivariate logistic regression analysis was performed to identify factors independently associated with the risk for BSI by the colonizing organism.
Results: Of 677 rectal carriers, 382/677 (56.4%) were colonized by NDM, 247/677 (36.5%) by KPC, 39/677 (5.8%) by VIM and 9/677 (1.3%) by OXA-48. Dissemination of NDM-Kp was mostly sustained by ST147, while KPC-Kp belonged to ST512. A higher rate of BSI was documented in NDM rectal carriers compared with KPC rectal carriers (59/382, 15.4% versus 20/247, 8.1%, p 0.004). Incidence rates of BSI per 100 patients/month were significantly higher in the NDM group (22.33, 95% CI 17.26-28.88) than in the KPC group (9.56, 95% CI 6.17-14.82). On multivariate analysis, multi-site extraintestinal colonization, solid organ transplantation, invasive procedures, intravascular device, admission to intensive care unit, cephalosporin, fluoroquinolones and NDM rectal colonization (OR 3.27, 95% CI 1.73-6.18, p < 0.001) were independently associated with BSI.
Conclusions: NDM-Kp was associated with increased risk of BSI compared with KPC-Kp. This finding seems to be strongly related to the high-risk clone ST147
Strong and auxiliary forms of the semi-Lagrangian method for incompressible flows
We present a review of the semi-Lagrangian method for advection-diusion and incompressible Navier-Stokes equations discretized with high-order methods. In particular, we compare the strong form where the departure points are computed directly via backwards integration with the auxiliary form where an auxiliary advection equation is solved instead; the latter is also referred to as Operator Integration Factor Splitting (OIFS) scheme. For intermediate size of time steps the auxiliary form is preferrable but for large time steps only the strong form is stable
Fertility-sparing treatment for intramucous, moderately differentiated, endometrioid endometrial cancer: A gynecologic cancer inter-group (GCIG) study
Objective: ‘The Endometrial Cancer Conservative Treatment (E.C.Co.). A multicentre archive’ is a worldwide project endorsed by the Gynecologic Cancer Inter-Group, aimed at registering conservatively treated endometrial cancer (EC) patients. This paper reports the oncological and reproductive outcomes of intramucous, G2, endometrioid EC patients from this archive. Methods: Twenty-three patients (Stage IA, G2, endometrioid EC) were enrolled between January 2004 and March 2019. Primary and secondary endpoints were, respectively, complete regression (CR) and recurrence rates, and pregnancy and live birth rates. Results: A median follow-up of 35 months (9–148) was achieved. Hysteroscopic resection (HR) plus progestin was adopted in 74% (17/23) of cases. Seventeen patients showed CR (median time to CR, 6 months; 3-13). Among the 6 non-responders, one showed persistence and 5 progressed, all submitted to definitive surgery, with an unfavorauble outcome in one. The recurrence rate was 41.1%. Ten (58.8%) complete responders attempted to conceive, of whom 3 achieved at least one pregnancy with a live-birth. Two out of the 11 candidate patients underwent definitive surgery, while the remaining 9 have so far refused. To date, 22 patients show no evidence of disease, and one is still alive with disease. Conclusions: Fertility-sparing treatment seems to be feasible even in G2 EC, although caution should be kept considering the potential pathological undergrading or non-endometrioid histology misdiagnosis. The low rate of attempt to conceive and of compliance to definitive surgery underline the need for a ‘global’ counselling extended to the follow-up period
Atypical COVID-19 dynamics in a patient with mantle cell lymphoma exposed to rituximab
Patients with non-hodgkin lymphomas (NHL) represent a population of special interest during the current Coronavirus disease-19 (COVID-19) pandemics. NHLs are associated with disease- and treatment-related immunodeficiencies which may generate unusual COVID-19 dynamics and pose unique management challenges. We report the unusual clinical course of COVID-19 in a patient with mantle cell lymphoma (MCL) exposed to nine doses of Rituximab shortly before infection with severe acute respiratory syndrome corona virus 2 (SARS-CoV-2). He had a prolonged asymptomatic phase, with negative molecular and antibody testing for SARS-CoV-2, followed by a rapidly progressive evolution to severe COVID-19. Despite detection of viral RNA overlapped with first symptoms occurrence, anti-SARS-CoV-2 antibodies displayed an asynchronous pattern, with IgG first appearing 2Â days after RNA positivity and IgM never being detected throughout the entire clinical course. While disease-associated immune derangements and/or previous treatments involving anti-CD20 antibodies might have contributed to COVID-19 dynamics in our patient, data suggests that antibody testings, without concurrent molecular assessment for SARS-CoV-2, may turn inadequate for monitoring of MCL patients, and in general NHL patients heavily exposed to anti-CD20 antibodies, during the current pandemics. We suggest that repeated molecular testing of nasopharyngeal swab should be implemented in these subjects despite a negative serology and absence of symptoms of SARS-CoV-2 infection. For the same reasons, a customized strategy needs to be developed for patients exposed to anti-CD20 antibodies, based on different features and mechanism of action of available SARS-CoV-2 vaccines and novel vaccinomics developments
The early X-ray afterglows of optically bright and dark Gamma-Ray Bursts
A systematical study on the early X-ray afterglows of both optically bright
and dark gamma-ray bursts (B-GRBs and D-GRBs) observed by Swift has been
presented. Our sample includes 25 GRBs. Among them 13 are B-GRBs and 12 are
D-GRBs. Our results show that the distributions of the X-ray afterglow fluxes
(), the gamma-ray fluxes (), and the ratio ()
for both the D-GRBs and B-GRBs are similar. The differences of these
distributions for the two kinds of GRBs should be statistical fluctuation.
These results indicate that the progenitors of the two kinds of GRBs are the
same population. Their total energy explosions are comparable. The suppression
of the optical emissions from D-GRBs should results from circumburst but not
their central engine.Comment: 10 pages, 3 figures, 1 table; accepted by ChJA
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