Proximate controls on semiarid soil greenhouse gas fluxes across 3 million years of soil development

Soils are important sources and sinks of three greenhouse gases (GHGs): carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). However, it is unknown whether semiarid landscapes are important contributors to global fluxes of these gases, partly because our mechanistic understanding of soil GHG fluxes is largely derived from more humid ecosystems. We designed this study with the objective of identifying the important soil physical and biogeochemical controls on soil GHG fluxes in semiarid soils by observing seasonal changes in soil GHG fluxes across a three million year substrate age gradient in northern Arizona. We also manipulated soil nitrogen (N) and phosphorus availability with 7 years of fertilization and used regression tree analysis to identify drivers of unfertilized and fertilized soil GHG fluxes. Similar to humid ecosystems, soil N2O flux was correlated with changes in N and water availability and soil CO2 efflux was correlated with changes in water availability and temperature. Soil CH4 uptake was greatest in relatively colder and wetter soils. While fertilization had few direct effects on soil CH4 flux, soil nitrate was an important predictor of soil CH4 uptake in unfertilized soils and soil ammonium was an important predictor of soil CH4 uptake in fertilized soil. Like in humid ecosystems, N gas loss via nitrification or denitrification appears to increase with increases in N and water availability during ecosystem development. Our results suggest that, with some exceptions, the drivers of soil GHG fluxes in semiarid ecosystems are often similar to those observed in more humid ecosystems

Strain-stiffening in random packings of entangled granular chains

Random packings of granular chains are presented as a model polymer system to investigate the contribution of entanglements to strain-stiffening in the absence of Brownian motion. The chain packings are sheared in triaxial compression experiments. For short chain lengths, these packings yield when the shear stress exceeds a the scale of the confining pressure, similar to packings of spherical particles. In contrast, packings of chains which are long enough to form loops exhibit strain-stiffening, in which the effective stiffness of the material increases with strain, similar to many polymer materials. The latter packings can sustain stresses orders-of-magnitude greater than the confining pressure, and do not yield until the chain links break. X-ray tomography measurements reveal that the strain-stiffening packings contain system-spanning clusters of entangled chains.Comment: 4 pages, 4 figures. submitted to Physical Review Letter

Localized Structures in Indented Shells: A Numerical Investigation

We present results from a numerical investigation of the localization of deformation in thin elastomeric spherical shells loaded by differently shaped indenters. Beyond a critical indentation, the deformation of the shell ceases to be axisymmetric and sharp structures of localized curvature form, referred to as “s-cones,” for “shell-cones.” We perform a series of numerical experiments to systematically explore the parameter space. We find that the localization process is independent of the radius of the shell. The ratio of the radius of the shell to its thickness, however, is an important parameter in the localization process. Throughout, we find that the maximum principal strains remain below 6%, even at the s-cones. As a result, using either a linear elastic (LE) or hyperelastic constitutive description yields nearly indistinguishable results. Friction between the indenter and the shell is also shown to play an important role in localization. Tuning this frictional contact can suppress localization and increase the load-bearing capacity of the shell under indentation.National Science Foundation (U.S.) (1122374)National Science Foundation (U.S.) (CMMI-1351449

Cardiovascular risk markers in patients with primary aldosteronism: A systematic review and meta-analysis of literature studies

Background/objectives: Several studies reported an increased cardiovascular (CV) morbidity and mortality in patients with primary aldosteronism (PA). We performed a meta-analysis on the impact of PA on major markers of CV risk. Methods: Studies on the relationship between PA and common carotid artery intima-media thickness (CCA-IMT), prevalence of carotid plaques, flow-mediated dilation (FMD), nitrate-mediated dilation (NMD), pulse-wave velocity (PWV), augmentation index (AIx), and ankle-brachial index (ABI) were systematically searched in the PubMed, Web of Science, Scopus and EMBASE databases. Results: 12 case-control studies (445 cases, 472 controls) were included. Compared to subjects with essential hypertension (EH), PA patients showed a higher CCA-IMT (MD: 0.12 mm; 95% CI: 0.09, 0.16; P<0.00001), and a higher aortic-PWV (272 cases and 240 controls, MD: 1.39 m/s; 95% CI: 0.90, 1.87; P<0.00001). In contrast, non-significant differences were found in AIx and AIx normalized to a heart rate of 75 beats per minute (AIx@75). When compared to normotensive subjects, PA patients showed significantly higher CCA-IMT (MD: 0.16 mm; 95% CI: 0.05, 0.27; P=0.004), aortic-PWV (MD: 3.74 m/s; 95% CI: 3.43, 4.05; P<0.00001), AIx@75 (MD: 8.59%; 95% CI: 0.69, 16.50; P=0.03), and a significantly lower FMD (MD: -2.52%; 95% CI: -3.64, -1.40; P<0.0001). Sensitivity and subgroup analyses substantially confirmed our results. Metaregression models showed that male gender, diabetes, and smoking habit impact on the observed results. Conclusions: PA appears significantly associated with markers of subclinical atherosclerosis and CV risk. These findings could help establish more specific CV prevention strategies in this clinical setting

Cross Sections From Scalar Field Theory

A one pion exchange scalar model is used to calculate differential and total cross sections for pion production through nucleon- nucleon collisions. The collisions involve intermediate delta particle production and decay to nucleons and a pion. The model provides the basic theoretical framework for scalar field theory and can be applied to particle production processes where the effects of spin can be neglected

Population genomics of an endemic Mediterranean fish: differentiation by fine scale dispersal and adaptation

The assessment of the genetic structuring of biodiversity is crucial for management and conservation. For species with large effective population sizes a low number of markers may fail to identify population structure. A solution of this shortcoming can be high-throughput sequencing that allows genotyping thousands of markers on a genome-wide approach while facilitating the detection of genetic structuring shaped by selection. We used Genotyping-by-Sequencing (GBS) on 176 individuals of the endemic East Atlantic peacock wrasse (Symphodus tinca), from 6 locations in the Adriatic and Ionian seas. We obtained a total of 4,155 polymorphic SNPs and we observed two strong barriers to gene flow. The first one differentiated Tremiti Islands, in the northwest, from all the other locations while the second one separated east and south-west localities. Outlier SNPs potentially under positive selection and neutral SNPs both showed similar patterns of structuring, although finer scale differentiation was unveiled with outlier loci. Our results reflect the complexity of population genetic structure and demonstrate that both habitat fragmentation and positive selection are on play. This complexity should be considered in biodiversity assessments of different taxa, including non-model yet ecologically relevant organisms

Delayed Treatment and Missed Opportunities for Limb Salvage in Patients with Peripheral Arterial Embolism

BACKGROUND: The peripheral arterial embolism (PAE) is a sudden decrease in limb perfusion due to acute occlusion of peripheral artery which leads to ischemic tissue damage, that can threaten the limb of a patient and requires immediate revascularization. It is estimated that the incidence of acute limb emoblism in the general population is around 14/100,000 inhabitants per year. Accurate and timely diagnosis is crucial to salvage the patient’s limb and sometimes the patient’s life. In cases of complete arterial occlusion and absence of collateral perfusion, irreversible damage can occur within 4 to 6 hours. The fundamental definition for treatment of acute peripheral arterial embolism is revascularisation. Revascularisation is either performed endovascularly or by an open surgical approach. A suspicion of acute ischemia based on history and physical examination warrants heparin administration and vascular surgery consultation. Delays in the management of acute peripheral arterial ischemia due to an embolism are common and associated with poor limb - salvage outcomes. AIM: Our study aims to identify medical consultations and cardiovascular assessments undergone by patients in the period prior to being hospitalised, in order to evaluate for missed or delayed opportunities for diagnosis. METHODS: Retrospective cohort study, utilising the medical documentation and previous outpatiently or inhospital consultations. Adult patients undergone treatment due to peripheral arterial embolism were identified and analyzed. Patients were identified through the administrative hospital database using the International Classification of Diseases. Hospitalised patients with those medcodes between 1st January 2010 - 1st March 2020 were recorded. RESULTS: Following exclusion, 424 patients (mean age 68.5 ± 5.85 years) were included. 159 patients (66.8%) had visited their family doctors or other medical specialist before admission and in all of the cases was initiated therapeutic approach. The rest of the cohort 79 patients (33.2%) presented lately due to other social reasons. The group of 159 patients that admitted lately due to medical indications - diagnostic, healthcare - administrative or treatment related problems are subject of our study. The largest group including 113 (71%) patients were treated outpatientley by vascular surgeons with preventative medications.17 patients (10.6%) were directed outpatientley to orthopaedic surgeon due to suspicion of trauma.15 patients (9.4%) were treated by their family doctors with pain relief medications. The rest of the 14 patients (8.8%) were treated by neurosurgeons or neurologists due to a suspicion of cauda eniqua and other neuropathies. The majority of the patients 108 (67.9%) were free of complains at the discharge, 11.3% of the studied cohort were with minimal post-treatment complains (numbness, coldness, absent peripheral pulsations, insignificant claudicatio). Amputation rate was 14.4%, incidence of rethrombosis 8.8% and recurrent embolism frequency around 3.7%. Death was registered in 21 cases (13.2%). CONCLUSION: The consequences of acute limb embolism such as prolonged hospitalization, major limb amputation, and/or death have a profound socioeconomic impact. Unrecognition of this vascular pathology and differential diagnosis difficulties are possibly leading factors for delayed or missed treatment

Ultrasound diagnosis of appendiceal tumor with synchronous liver metastasis mimicking acute appendicitis and liver abscess

Appendiceal tumors (AT) are rare gastrointestinal cancers with high incidence of synchronous and metachronous colorectal cancer metastases. AT are rarely associated with hepatic metastases. Sometimes, metastases are the first evidence of the tumor. We report the clinical, surgical and imaging records of a female patient, 81 years old, admitted for a suspect liver abscess, only subsequently diagnosed as metastasis from an undiagnosed AT. Ultrasound (US) based imaging techniques, such as Color-Doppler Ultrasound, Contrast enhanced US, US-guided biopsy of the hepatic nodule played an important role in the assessment of the definitive diagnosis

Neutrophil - Lymphocyte Ratio as a Reliable Predictor of Postoperative Outcome And Mortality In Delayed Cases Of Peripheral Arterial Embolism

Introduction: Peripheral arterial embolism (PAE) continues to pose a challenge to vascular surgeons and remains to be characterized by high morbidity, limb threat and mortality, often requiring urgent revascularization. Contemporary untreated arterial embolism is among the leading causes of morbidity and mortality within the vascular field. Detection of a fast and reliable biomarker for risk stratification and early post-treatment prognosis is important for those with PAE, so that individuals at high risk can be accurately treated and targeted for prevention. Complete blood count is inexpensive, comparatively routine, and is a practical laboratory test that gives important information about the patient’s formed blood contents. Routine peripheral blood counts may be useful in diagnosis and prognosis of many disorders, including peripheral vascular ischemic incidents. Neutrophil - lymphocyte ratio (NLR) has been shown to be an independent predictor of early and midterm amputation in patients with acute limb ischemia after revascularisation. Methods: Data was collected retrospectively from hospitalised patients, in the Vascular Surgery Clinic of University Hospital, Stara Zagora, Bulgaria, who had a diagnosis of PAE, from January 2010 to January 2019. Inclusion criteria were clinical data of an ischemic embolic incident of the limbs, untreated at least 12 hours from the onset of symptoms. Results: A single cutoff point was chosen to better inform clinical practice at a value of NLR 4.55, to maximize sensitivity and specificity. The majority of patients from the group Who had a NLR under 4.55 had mild symptoms. Older patients however, were significantly more likely to have an elevated NLR. The incidence of diabetes and hypertension were not significantly higher in any group. There was a higher incidence of primary major amputations in the elevated NLR group. Of the 25 deaths during the course of the study, which were specifically attributed to cardiac causes, twelve (13.8%) occurred within the elevated NLR group and thirteen (8.7%) in the low NLR group. Conclusion: NLR is an easily accessible biomarker that conveys important information about the patient’s inflammatory activity and can be easily calculated from the differential WBC count, which is routinely performed on admission and is universally available. An elevated NLR could potentially be included in addition to the most common risk factors for mortality and poor post-treatment outcome including cardiac causes, age &gt;70 years, history of stroke or previous MI, renal failure, and smoking history (at any time)

Distal junctional kyphosis in patients with Scheuermann’s disease: a retrospective radiographic analysis

Purpose To investigate the relationship between preoperative and postoperative spinopelvic alignment and occurrence of DJK/DJF. Study design/setting This was a retrospective observational cohort study. Patient sample The sample included 40 patients who underwent posterior correction of SK from January 2006 to December 2014. Outcome measures Correlation analysis between the preoperative and postoperative spinopelvic alignment parameters and development of DJK over the course of the study period were studied. Methods Whole spine X-rays obtained before surgery, 3 months after surgery and at the latest follow-up were analyzed. The following parameters were measured: maximum of thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lower instrumented vertebra (LIV) and LIV plumb line. Development of DJK was considered as the primary end point of the study. The patient population was split into a control and DJK group, with 34 patients and 6 patients, respectively. Statistic analysis was performed using unpaired t test for normal contribution and Mann–Whitney test for skew distributed values. The significance level was set to 0.05. Results DJK occurred in 15% (n = 6) over the study period. There was a significantly lower postoperative TK for the group with DJK (42.4 ± 5.3 vs 49.8 ± 6.7, p = 0.015). LIV plumb line showed higher negative values in the DJK group (−43.6 ± 25.1 vs −2.2 ± 17.8, p = 0.0435). Furthermore, postoperative LL changes were lower for the DJK group (33.84 ± 13.86% vs 31.77 ± 14.05, p < 0.0001.) The age of the patients who developed DJK was also significantly lower than that of the control group (16.8 ± 1.7 vs 19.6 ± 4.9, p = 0.0024.) Conclusions SK patients who developed DJK appeared to have a significantly higher degree of TK correction and more negative LIV plumb line. In addition, there may be a higher risk for DJK in patients undergoing corrective surgery at a younger age