Coherent vs incoherent interlayer transport in layered metals

The magnetic-field, temperature, and angular dependence of the interlayer magnetoresistance of two different quasi-two-dimensional (2D) organic superconductors is reported. For $\kappa$-(BEDT-TTF)$_2$I$_3$ we find a well-resolved peak in the angle-dependent magnetoresistance at $\Theta = 90^\circ$ (field parallel to the layers). This clear-cut proof for the coherent nature of the interlayer transport is absent for $\beta$''-(BEDT-TTF)$_2$SF$_5$CH$_2$CF$_2$SO$_3$. This and the non-metallic behavior of the magnetoresistance suggest an incoherent quasiparticle motion for the latter 2D metal.Comment: 4 pages, 4 figures. Phys. Rev. B, in pres

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Development of a Wien filter electron polarimeter

According to current ideas only left-handed fermion currents participate in the weak interaction. However there exist left-right symmetric variants of electroweak theory with right-handed currents which couple with equal intrinsic strength, whose contribution is suppressed by the presumed relatively greater mass of the mediating vector bosons. One route to detecting the presence of right-handed currents is to measure the velocity-dependence of the polarization of electrons from mixed Fermi/Gamow-Teller #beta#-transitions. This thesis describes the theory, construction and operation of a Wien filter which is a system of crossed uniform electric and magnetic fields which transmits electrons of velocity v = E/B, and is therefore an ideal instrument for precise velocity measurements. The filter is based on a 2.5 meter long uniform field electromagnet purpose built at Oak Ridge some thirty years ago to study the electric and magnetic dipole moments of the neutron. The thesis comes in two parts: the first part presents the exact theory of relativistic electron motion in an ideal crossed field system, together with numerical programs for examining the effects of imperfections of which electric field non-uniformity and remnant magnetism turn out to be the most important. This is followed by the constructional details of the velocity filter including electric and magnetic field measurements, vacuum performance and the method for detecting and processing electron signals. This part concludes with an account of the successful testing of the filter using 62.5 keV and 84.5 keV internal conversion electrons from an electron-capture source of 453 day "1"0"9Cd. The second part of the thesis deals with the dynamics of electron spin motion in crossed fields; in particular with spin rotation from longitudinal to transverse orientation which is necessary for applying the method of Mott scattering from heavy nuclei for electron polarization determination. This part also describes the Mott-scattering chamber arid the electron detection system used to measure the left-right counting asymmetry which is characteristic of electron polarization. An initial attempt to detect a scattering asymmetry using electrons from the pure Gamow-Teller of 24-day "3"3P was largely unsuccessful, mainly because of the short-lived nature of the source combined with misalignment and background problems. (author)SIGLEAvailable from British Library Document Supply Centre-DSC:DXN028931 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

A Histopathologic Study on Pulp Response to Glass Ionomer Cements in Human Teeth

Statement of Problem: Despite the wide range of new dental materials, there is still a need for biomaterials demonstrating high biocompatibility, antimicrobial effects and ideal mechanical properties.Purpose: The aim of this study was to histologically evaluate the pulpal response to a conventional glass ionomer, a resin modified glass ionomer and a calcium hydroxide in human teeth.Materials and Methods: Fifty five deep class V cavities were prepared in premolars of 31 patients and were divided into 3 groups based on application of the following liners:resin modified glass ionomer (Vivaglass Liner), conventional glass ionomer (ChembondSuperior) and calcium hydroxide (Dycal). After applying varnish, teeth were filled with amalgam. Each group was further divided into three subgroups according to time intervals of 7, 30 and 60 days. Teeth were then extracted and their crowns were fixed in formalin. Each sample was assessed microscopically for odontoblastic changes,inflammatory cell infiltration, reactionary dentin formation, remaining dentinal thickness and presence of microorganisms. Statistical analysis including Kruskal Wallis and Mann Whitney was carried out for comparison of mean ranks. (P=0.05).Results: In the Vivaglass Liner group, pulpal response was significantly higher on day 7 as compared to days 30 and 60 (P<0.05). Reactionary dentin production was significantly lower after 7 days than after 60 days for all materials (P<0.05). There wasno statistically significant difference in pulpal responses among the three groups during the same time intervals (P>0.05). There was no correlation between pulpal responses with micro-organisms and remaining dentin thickness (P>0.05).Conclusion: According to the results of this study, light-cured glass ionomer as well as the other tested lining materials were determined to be biologically compatible with vital pulps in deep cavities of sound human teeth

A Comparison between Amalgam and MTA in Repairing Furcal Perforation

Objective: The purpose of this study was to investigate the histological response to delib-erate perforation repaired using amalgam or MTA either immediately or with delay on cats’ molars.Materials and Methods: Twenty-eight molar teeth from four cats were used in this ex-perimental randomized study. After preparing the access cavity, the floor of pulp cham-bers were deliberately perforated with a round bur No. 5. The teeth were randomly divided into four groups of seven. In groups one and two,the perforation was immediately sealed with amalgam and MTA, respectively. In groups three and four, the perforations were leftexposed to saliva for six weeks and then sealed with amalgam or MTA. The animals were sacrificed four months later and the specimens processed. The samples were blindly exam-ined for inflammatory reaction and healing process under light microscope. The data were analyzed with Mann-Whitney U and Fisher exact tests.Results: The type of the materials used has no significant effect on the severity of in-flammation; while, immediate or delayed repair of furcal perforation has, and immediate application of, MTA produced less inflammation than that of amalgam (P<0.05). No dif-ferences were found in vasodilatation, abscess formation or healing process between the immediate and the delayed repair groups (P=0.13).Conclusion: MTA is a more suitable material than amalgam for perforation repair, par-ticularly when used immediately after perforation

Role of Calcium to Citrate Ratio in Predicting Stone Formation in Idiopathic Hypercalciuria Children (2-12 Years Old)

Objective: Considering the predictive role of the relatively low urinary citrate for stone formation, especially in hypercalciuric patients, this study is aimed at comparing urine calcium to citrate (Ca/Cit) ratio in 3 groups of children, including patients with idiopathic hypercalciuria with and without renal stone as well as the healthy children. Methods: This study was carried out on 96 children (2 to 12 years old) referred to a pediatric nephrology clinic in the city of Ahvaz, Southwest Iran. All the children underwent renal ultrasonography, urinalysis, and measurement of random nonfasting urine Ca, Cr, and citrate. Those with secondary hypercalciuria, urinary tract malformations, and/or functional abnormalities of the gastrointestinal tract were excluded from the study. Results: The mean Ca/Cit. ratio (mg/mg) in the three groups, including children with hypercalciuric with and without renal stones and the healthy children (control group), was 0.44 ± 0.14, 0.39 ± 0.13, and 0.19 ± 0.08, respectively, which showed a significant difference (P <.001). There was also a significant difference in Ca/Cit ratio between the first and the control group by Tukey's range test (P <.001). Mean urinary Ca/Cit ratio in those with a positive family history of urolithiasis within three groups was 0.42 ± 0.17 and in those with a negative family history was 0.32 ± 0.16 (P =.013). Mean Ca/Cit. ratio (mg/mg) of 0.25 showed a sensitivity of 90.6 (confidence interval: 75.7-96.7) and a specificity of 81.2 (confidence interval: 64.7-91.1) to differentiate between the renal stone group and the control group. Conclusion: High Ca/Cit ratio can predict stones formation in hypercalciuric patients, especially in those with a positive family history of urolithiasis. The present study found the cutoff level of 0.25 for Ca/Cit. ratio as the highest prognostic value for renal stone formation. © 2018 National Kidney Foundation, Inc

Histologic evaluation of repair of mechanical furcal perforations in dog premolars, using gray MTA, white MTA &amp; Portland cement

Background and Aim: Furcal perforation has a great impact on prognosis of endodontic treatments, requiring immediate and proper intervention. Gray MTA is applied as material of choice in repairing perforations. The aim of this study was to evaluate the repair of mechanical furcal perforations, histologically using white MTA and Portland cement and compare them with gray MTA. Materials and Methods: In this experimental study, second to fourth mandibular and maxillary premolar teeth of five dogs received endodontic treatment, then the furcation area of the teeth were perforated and repaired as follow: gray MTA in group1, white MTA in group 2, Portland cement in group 3 and cotton pellet in group 4 (control). Animals were controlled for 4 months and sacrificed using an over dosage of sodium thiopental intravenous injection and perfusion of 10% formaldehyde. Chi-square and Fisher exact tests were used to compare hard tissue formation between groups and between each two groups, respectively. Non-parametric Kruskall Wallis and Dunn procedure were also used to compare degree of inflammation among groups and between each two groups, respectively. Results: Gray MTA had more favorable results (90.9% hard tissue formation and only 9.1% severe inflammation) but the difference between gray MTA, white MTA and Portland cement was not statistically significant. Conclusion: The difference between gray MTA, white MTA and Portland cement groups was not statistically significant for degree of inflammation and hard tissue formation. In conclusion both white MTA and Portland cement can be used instead of gray MTA to repair perforations in accordance to esthetic considerations