A Radial Basis Function Method with Improved Accuracy for Fourth Order Boundary Value Problems

Accurately approximating higher order derivatives is an inherently difficult problem. It is shown that a random variable shape parameter strategy can improve the accuracy of approximating higher order derivatives with Radial Basis Function methods. The method is used to solve fourth order boundary value problems. The use and location of ghost points are examined in order to enforce the extra boundary conditions that are necessary to make a fourth-order problem well posed. The use of ghost points versus solving an overdetermined linear system via least squares is studied. For a general fourth-order boundary value problem, the recommended approach is to either use one of two novel sets of ghost centers introduced here or else to use a least squares approach. When using either ghost centers or least squares, the random variable shape parameter strategy results in significantly better accuracy than when a constant shape parameter is used.

Local Radial Basis Function Methods: Comparison, Improvements, and Implementation

Radial Basis Function methods for scattered data interpolation and for the numerical solution of PDEs were originally implemented in a global manner. Subsequently, it was realized that the methods could be implemented more efficiently in a local manner and that the local approaches could match or even surpass the accuracy of the global implementations. In this work, three localization approaches are compared: a local RBF method, a partition of unity method, and a recently introduced modified partition of unity method. A simple shape parameter selection method is introduced and the application of artificial viscosity to stabilize each of the local methods when approximating time-dependent PDEs is reviewed. Additionally, a new type of quasi-random center is introduced which may be better choices than other quasi-random points that are commonly used with RBF methods. All the results within the manuscript are reproducible as they are included as examples in the freely available Python Radial Basis Function Toolbox.

A Filtered Milne-Simpson ODE Method with Enhanced Stability Properties

The Milne-Simpson method is a two-step implicit linear multistep method for the numerical solution of ODEs that obtains the theoretically highest order of convergence for such a method. The stability region of the method is only an interval on the imaginary axis and the method is classified as weakly stable which causes non-physical oscillations to appear in numerical solutions. For this reason, the method is seldom used in applications. This work examines filtering techniques that improve the stability properties of the Milne-Simpson method while retaining its fourth-order convergence rate. The resulting filtered Milne-Simpson method is attractive as a method of lines integrator of linear time-dependent partial differential equations.

Physician-scientists or celebrities?Kardashian-index of gastroenterologists

BACKGROUND The coronavirus disease 2019 pandemic unleashed a flood of untrustworthy information on social media platforms,resulting in the unfortunate consequence of expert scientists'opinions getting lost amidst the chaotic sea of misinformation.The question of how much influence these esteemed scientists hold on social media platforms remains elusive.To address this scientific quandary,we sought to explore the concept of the Kardashian index(K-index),a term introduced by Hall in 2014.This metric provides a rudimentary means of evaluating whether a physician scientist's popularity on social media aligns with their significant scientific contributions.AIM To evaluate if a Gastroenterologist physician's popularity on social media is at par with their scientific contributions(research articles and publications).METHODS We conducted an extensive search to identify all gastroenterologists actively practicing and associated with the top 100 hospitals as reported by the United States News.We collected specific data on a sub-group including their names,affiliations,degrees,and sub-specializations.To gauge their social media popularity,we utilized the K-index calculation which is determined by dividing the actual number of Twitter followers by the number of researcher’s citations.The expected number of followers(F)is calculated using the formula F=43.3 C^0.32,where C represents the number of citations.RESULTS Physicians affiliated with the Mayo Clinic emerged as the most prominent presence on Twitter,constituting 16%of the total.They were followed closely by physicians from Mount Sinai Hospital(9%)and the University of Michigan Hospital(9%).Surprisingly,76%of the physicians evaluated exhibited a low K-index,falling within the range of 0 to less than 2.This suggests that a significant number of highly influential physician-scientists are not receiving due recognition,as indicated by their relatively low number of followers.On the other hand,24%of the physicians had an inflated K-index,exceeding 5,which positioned them as the"Kardashians".These individuals enjoyed greater social media popularity than their actual scientific contributions.Interestingly,our analysis revealed no discernible association between sex and K-index(P value of 0.92).CONCLUSION In the gastroenterology field,our study estimated that a majority(76%)of highly researched physicians are undervalued despite their significant scientific contributions.

抗菌肽及其应用前景概述

抗菌肽是生物体产生的一种具有抗菌活性的多肽类物质,它对细菌、真菌和病毒等都具有明显的杀伤作用。抗菌肽有望开发成为防治人和动物疾病的药物,应用前景广阔。文章对抗菌肽的结构特征、作用机制及应用前景进行了综述,以期为抗菌肽的更深层次的研究与应用提供参考。

A new direction for Alzheimer's research

Despite decades of research, at present there is no curative therapy for Alzheimer＇s disease. Changes in the way new drugs are tested appear to be necessary. Three changes are presented here and will be discussed. The first change is that Alzheimer＇s disease must be considered a disease of four major pathological processes, not one. The four processes are： 1） vascular hy- poperfusion of the brain with associated mitochondrial dysfunction, 2） destructive protein inclusions, 3） uncontrolled oxidative stress, and 4） proinflammatory immune processes second- ary to microglial and astrocytic dysfunction in the brain. The second change recommended is to alter the standard cognitive measurement tools used to quantify mental decline in test patients. Specifically the Dementia Severity Rating Scale （DSRS） should supersede Mini-Mental State Examination （MMSE） and other popular tests, and a measurement scale developed in research should be used to produce a linear and non-irregular baseline. Finally, accepting the concept that four etiologies cause Alzheimer＇s disease leads to the last necessary change, that new thera- pies must be employed directed against all four causes, likely as a combination. There are drugs ready to be employed in such a combinations which are available and used clinically for other purposes so can be used ＂offlabel＂ and one such combination is suggested.

Wind-induced instabilities and monitoring of wind turbine

This paper presents real-time monitoring data and analysis results of the non-stationary vibrations of an operational wind turbine. The advanced time-frequency spectrum analysis reveals varied non-stationary vibrations with timevarying frequencies, which are correlated with certain system natural modes characterized by finite element analysis. Under the effects of strong wind load, the wind turbine system exhibits certain resonances due to blade passing excitations. The system also exhibits certain instabilities due to the coupling of the tower bending modes and blade flapwise mode with blade passing excitations under the variation of wind speed. An analytical model is used to elaborate the non-stationary and instability phenomena observed in experimental results. The properties of the nonlinear instabilities are evaluated by using Lyapunov exponent estimation.

Laboratory testing of a shuttle car canopy air curtain for respirable coal mine dust control

Canopy air curtain （CAC） technology has been developed by the National Institute for Occupational Safety and Health （NIOSH） for use on continuous miners and subsequently roof bolting machines in underground coal mines to protect operators of these machines from overexposure to respirable coal mine dust. The next logical progression is to develop a CAC for shuttle cars to protect operators from the same overexposures. NIOSH awarded a contract to Marshall University and J.H. Fletcher to develop the shuttle car CAC. NIOSH conducted laboratory testing to determine the dust control efficiency of the shuttle car CAC. Testing was conducted on two different cab configurations： a center drive similar to that on a Joy 10SC32AA cab model and an end drive similar to that on a Joy 10SC32AB cab model. Three different ventilation velocities were tested-0.61, 2.0, 4.3 rrds （120, 400, and 850 fpm）. The lowest, 0.61 m/s （120 fpm）, represented the ventilation velocity encountered during loading by the continuous miner, while the 4.3 m/s （850 fpm） velocity represented ventilation velocity airflow over the shuttle car while tramming against ventilation airflow. Test results showed an average of the dust control efficiencies ranging from 74 to 83% for 0.61 m/s （120 fpm）, 39%-43% for 2.0 m/s （400 fpm）, and 6%-16% for 4.3 m/s （850 fpm）. Incorporating an airflow spoiler to the shuttle car CAC design and placing the CAC so that it is located 22.86 cm （9 in.） forward of the operator improved the dust control efficiency to 51%-55% for 4.3 m/s （850 fpm） with minimal impact on dust control efficiencies for lower ventilation velocities. These laboratory tests demonstrate that the newly developed shuttle car CAC has the potential to successfully protect shuttle car operators from coal mine respirable dust overexposures.

Bilateral renal cortical necrosis associated with smoking synthetic cannabinoids

Synthetic cannabinoids have become a common drug of abuse in recent years and their toxicities have come to light as well. They are known to be notorious for the kidneys, with acute tubular necrosis, acute interstitial nephritis and rhabdomyolysis induced renal injury being the frequent nephrotoxic outcomes in users. We report a case of bilateral renal cortical necrosis, leading to irreversible renal damage and lifelong dialysis dependency.

Confounding factors affect the pathophysiology of eosinophilic esophagitis

Eosinophilic esophagitis is a newly diagnosed esophageal disease in adult and children. The clinical and pathological characteristics of this disease have been established and were recently summarized in the expert clinical guideline published in 2011. In spite of the wide knowledge accumulated on this disease, there are many areas where scientific data are missing, especially in regard to the disease's pathophysiology. Recent publications have suggested that other confounding factors modify the disease and may affect its clinicalphenotypic presentation. Those factors may include place of living, air pollution, race, genetic factors and other. In the present report we discussed and review those confounding factors, the new developments, and what direction we should go to further advance our knowledge of this disease.

Establishing the presence or absence of chronic kidney disease:Uses and limitations of formulas estimating the glomerular filtration rate

The development of formulas estimating glomerular filtration rate(eG FR) from serum creatinine and cystatin C and accounting for certain variables affecting the production rate of these biomarkers, including ethnicity, gender and age, has led to the current scheme of diagnosing and staging chronic kidney disease(CKD),which is based on e GFR values and albuminuria.This scheme has been applied extensively in various populations and has led to the current estimates of prevalence of CKD. In addition, this scheme is applied in clinical studies evaluating the risks of CKD and the efficacy of various interventions directed towards improving its course. Disagreements between creatinine-based and cystatin-based e GFR values and between e GFR values and measured GFR have been reported in various cohorts. These disagreements are the consequence of variations in the rate of production and in factors, other than GFR, affecting the rate of removal of creatinine and cystatin C. The disagreements create limitations for all e GFR formulas developed so far. The main limitations are low sensitivity in detecting early CKD in several subjects, e.g., those with hyperfiltration, and poor prediction of the course of CKD. Research efforts in CKD are currently directed towards identification of biomarkers that are better indices of GFR than the current biomarkers and,particularly, biomarkers of early renal tissue injury.

Polyethylene glycol 3350 based colon cleaning protocol: 2 d vs 4 d head to head comparison

AIM: To compare between 2 and 4 d colon cleansing protocols. METHODS: Children who were scheduled for colonoscopy procedure (2010-2012) for various medical reasons, were recruited from the pediatric gastroenterology clinic at Marshall University School of Medicine, Huntington, WV. Exclusion criteria were patients who were allergic to the medication used in the protocols [polyethylene glycol (PEG) 3350, Bisacodyl], or chil- dren with metabolic or renal diseases. Two PEG 3350 protocols for 4 d (A) and 2 d (B) were prescribed as previously described. A questionnaire describing the volume of PEG consumed, clinical data, and side effects were recorded. Colon preparation was graded by two observers according to previously described method. Main outcome measurements: Rate of adequate colon preparation. RESULTS: A total of 78 patients were considered for final calculation (group A: 40, group B: 38). Age and stool consistency at the last day was comparable in both groups, but the number of stools/day was significantly higher in group B (P = 0.001). Adequate colonpreparation was reached in 57.5% (A) and 73.6% (B), respectively (P = 0.206). Side effects were minimal and comparable in both groups. There was no difference in children's age, stool characteristics, or side effects between the children with adequate or inadequate colon preparation. Correlation and agreement between observers was excellent (Pearson correlation = 0.972, kappa = 1.0). CONCLUSION: No difference between protocols was observed, but the 2 d protocol was superior for its shorter time. Direct comparison between different colon cleansing protocols is crucial in order to establish the "gold standard" protocol for children.

Imaging of common bile duct by linear endoscopic ultrasound

Imaging of common bile duct(CBD) can be done by many techniques. Endoscopic retrograde cholangiopancreaticography is considered the gold standard for imaging of CBD. A standard technique of imaging of CBD by endoscopic ultrasound(EUS) has not been specifically described. The available descriptions mention different stations of imaging from the stomach and duodenum. The CBD lies closest to duodenum and choice of imaging may be restricted to duodenum for many operators. Generally most operators prefer multi station imaging during EUS and the choice of selecting the initial station varies from operator to operator. Detailed evaluation of CBD is frequently the main focus of imaging during EUS and in such situations multi station imaging with a high-resolution ultrasound scanner may provide useful information. Examination of the CBD is one of the primary indications for doing an EUS and it can be done from five stations:(1) the fundus of stomach;(2) body of stomach;(3) duodenal bulb;(4) descending duodenum; and(5) antrum. Following down the upper 1/3rd of CBD can do imaging of entire CBD from the liver window and following up the lower 1/3rd of CBD can do imaging of entire CBD from the pancreatic window. This article aims at simplifying the techniques of imaging of CBD by linear EUS.

Dashing away hypertension: Evaluating the efficacy of the dietary approaches to stop hypertension diet in controlling high blood pressure

The dietary approaches to stop hypertension(DASH) diet has been developed and popularized as a nonpharmaceutical intervention for high blood pressure reduction since 1995.However,to date,a comprehensive description of the biochemical rationale behind the diet's principal guidelines has yet to be compiled.With rising interest for healthy and reliable life-style modifications to combat cardiovascular disease,this review aims to compile the most recent and relevant studies on this topic and make an informed assessment as to the efficacy of and underlying mechanisms operant in the DASH diet.Specifically,the merits of lowering dietary intake of sodium and saturated fat,as well as increasing the intake of fruits,vegetables,fiber,and dairy,have been shown to attenuate hypertension individually.Upon review of this evidence,we conclude that the combination of dietary patterns proposed in the DASH diet is effective in attenuating high blood pressure.We also suggest that efforts to more widely implement adoption of the DASH diet would be beneficial to public health.

Hyperglycemia Induced Changes in Vascular AKT3 May Inhibit Pressure-Induced Apoptosis in the Rat Inferior Venae Cavae

Background: Vein graft failure after bypass surgery is greatly increase in patients with diabetes mellitus. The cellular mechanisms underlying the cause of this failure are largely unexplored. Protein kinase B/AKT is a mechanically sensitive regulator of cellular growth and apoptosis. Herein we examine whether diabetes affects the regulation of AKT in response to increased venous loading. Methods: Inferior venae cavae (IVC) from the non-diabetic lean (LNZ) and the diabetic obese?syndrome X Zucker(OSXZ) rats were isolated and incubated ex vivo under basal or pressurized conditions (120 mmHg). Protein expression, basal activation and the ability of increased pressure to activate AKT3 and apoptosis-related signaling were evaluated by immunoblot analysis. Results: Compared to that seen in the non-diabetic lean animals, increased venous pressure in the OSXZ rats was not characterized by increases in APAF-1 concentration, XIAP proteolysis, AIF cleavage, or Bad phosphorylation. This evidence of decreased apoptotic signaling was associated with increased basal p-AKT3 levels (+136% ± 13% P < 0.05 higher in the OSXZ vs. LNZ IVC). Conclusion: These data suggest that diabetes-associated increases in p-AKT3 may alter the ability of the IVC to undergo pressure induced apoptosis-related signaling. Further investigation is required to determine whether these changes are associated with the increased vein graft attrition seen in the diabetic population.

A multilocus molecular phylogeny for the avian genus Liocichla(Passeriformes:Leiothrichidae:Liocichla)

Background:Historically the babblers have been assigned to the family Timaliidae but several recent studies have attempted to rest the taxonomy of this diverse passerine assemblage on a more firm evolutionary footing.The result has been a major rearrangement of the group.A well?supported and comprehensive phylogeny for this widespread avian group is an important part of testing evolutionary and biogeographic hypotheses,especially in Asia where the babblers are a key component of many forest ecosystems.However,the genus Liocichla is poorly represented in these prior studies of babbler systematics.Methods:We used a multilocus molecular genetic approach to generate a phylogenetic hypothesis for all five cur?rently recognized species in the avian genus Liocichla.Multilocus DNA sequence data was used to construct individ?ual gene trees using maximum likelihood and species trees were estimated from gene trees using Bayesian analyses.Divergence dates were obtained using a molecular clock approach.Results:Molecular data estimate a probable window of time for the origin for the Liocichla from the mid to late Miocene,between 5.55 and 12.87 Ma.Despite plumage similarities between the insular Taiwan endemic,L.steerii,and the continental L.bugunorum and L.omeiensis,molecular data suggest that L.steerii is the sister taxon to all continen?tal Liocichla.The continental Liocichla are comprised of two lineages;a lineage containing L.omeiensis and L.bugunorum and a lineage comprised of L.phoenicea and L.ripponi.The comparatively early divergence of L.steerii within the Liocichla may be illusory due to extinct and therefore unsampled lineages.L.ripponi and L.phoenicea are parapatric with a Pleistocene split(0.07–1.88 Ma) occurring between an Eastern Himalayan L.phoenicea and a Northern Indo?china distributed L.ripponi.L.bugunorum and L.omeiensis underwent a similar split between the Eastern Himalaya(L.bugunorum) and Central China(L.omeiensis) divided by the Hengduan Mountains.Conclusions:This study supports an origin of the Liocichla occurring sometime prior to the Miocene–Pliocene boundary,a period of significant climatic upheaval in Asia.The biogeographical patterns within the Liocichla mirror those of other birds in the region and allude to common geological and climatic drivers of avian diversification in Asia.

Hypertonicity:Clinical entities,manifestations and treatment

Hypertonicity causes severe clinical manifestations and is associated with mortality and severe short-term and long-term neurological sequelae. The main clinical syndromes of hypertonicity are hypernatremia and hyperglycemia. Hypernatremia results from relative excess of body sodium over body water. Loss of water in excess of intake, gain of sodium salts in excess of losses or a combination of the two are the main mechanisms of hypernatremia. Hypernatremia can be hypervolemic, euvolemic or hypo-volemic. The management of hypernatremia addresses both a quantitative replacement of water and, if present, sodium defcit, and correction of the underlying pathophysiologic process that led to hypernatremia. Hypertonicity in hyperglycemia has two components, solute gain secondary to glucose accumulation in the extracellular compartment and water loss through hyperglycemic osmotic diuresis in excess of the losses of sodium and potassium. Differentiating between these two components of hypertonicity has major therapeutic implications because the frst component will be reversed simply by normalization of serum glucose concentration while the second component will require hypotonic fuid replacement. An estimate of the magnitude of the relative water deficit secondary to osmotic diuresis is obtainedby the corrected sodium concentration, which representsa calculated value of the serum sodium concentrationthat would result from reduction of the serum glucoseconcentration to a normal level.

Fluid balance concepts in medicine:Principles and practice

The regulation of body fluid balance is a key concern in health and disease and comprises three concepts. The first concept pertains to the relationship between total body water(TBW) and total effective solute and is expressed in terms of the tonicity of the body fluids. Disturbances in tonicity are the main factor responsible for changes in cell volume, which can critically affect brain cell function and survival. Solutes distributed almost exclusively in the extracellular compartment(mainly sodium salts) and in the intracellular compartment(mainly potassium salts) contribute to tonicity, while solutes distributed in TBW have no effect on tonicity. The second body fluid balance concept relates to the regulation and measurement of abnormalities of sodium salt balance and extracellular volume. Estimation of extracellular volume is more complex and error prone than measurement of TBW. A key function of extracellular volume, which is defined as the effective arterial blood volume(EABV), is to ensure adequate perfusion of cells and organs. Other factors, including cardiac output, total and regional capacity of both arteries and veins, Starling forces in the capillaries, and gravity also affect the EABV. Collectively, these factors interact closely with extracellular volume and some of them undergo substantial changes in certain acute and chronic severe illnesses. Their changes result not only in extracellular volume expansion, but in the need for a larger extracellular volume compared with that of healthy individuals. Assessing extracellular volume in severe illness is challenging because the estimates of this volume by commonly used methods are prone to large errors in many illnesses. In addition, the optimal extracellular volume may vary from illness to illness, is only partially based on volume measurements by traditional methods, and has not been determined for each illness. Further research is needed to determine optimal extracellular volume levels in several illnesses. For these reasons, extracellular volume in severe illness merits a separate third concept of body fluid balance.

Filtered Leapfrog Time Integration with Enhanced Stability Properties

The Leapfrog method for the solution of Ordinary Differential Equation initial value problems has been historically popular for several reasons. The method has second order accuracy, requires only one function evaluation per time step, and is non-dissipative. Despite the mentioned attractive properties, the method has some unfavorable stability properties. The absolute stability region of the method is only an interval located on the imaginary axis, rather than a region in the complex plane. The method is only weakly stable and thus exhibits computational instability in long time integrations over intervals of finite length. In this work, the use of filters is examined for the purposes of both controlling the weak instability and also enlarging the size of the absolute stability region of the method.

炎症性肠病患儿血清学标志物诊断的准确性:西弗吉尼亚的一项经验

Goal: To assess the sensitivity/specificity of the serologic markers: perinuclear antineutrophil cytoplasmic antibody (pANCA) and anti- saccharomyces cerevisiae antibody (ASCA) in children diagnosed with inflammatory bowel disease (IBD), living in West Virginia. Background: In recent years, serologic markers have been used to differentiate between CD and UC diseases in children. The clinical usefulness of these markers in children was restricted by their low sensitivity and specificity. Racial and ethnic diversity may alter the accuracy of these markers in children. The demographic homogeneity of the West Virginia population may offer a better clinical setup to reassess the utility of those markers in children with IBD. Study: A retrospective analysis of all the charts of children diagnosed with IBD was performed at the gastroenterology clinics of Marshall University, Huntington, WV; and West Virginia University. Charleston Division, Charleston, WV The diagnosis of IBD was established according to clinical, radiologic, and endoscopic data. Laboratory data and serum markers were recorded, and their accuracy to diagnose UC or CD was assessed. Results: A total of 101 charts were reviewed, of which only 90 (89% ) included serologic markers and were considered for further analysis. Disease distribution included: UC- 41, CD- 44, and indeterminate colitis (IC)- 7 (2 patients changed diagnosis after colectomy). Serum antibody pANCA had a sensitivity of 73% and specificity of 84% for UC, but only 16% and 35% for CD, respectively. Serum antibody ASCA had a sensitivity of 58% and specificity of 92% for CD, but only 7% and 49% for UC. respectively. The outer membrane porin to Escherichia coli antibody (anti- OmpC) was available in 54 (59% ) children and demonstrated a very poor sensitivity for both diseases (sensitivity< 11% ). Conclusion: Despite our homogeneous patient population, pANCA and ASCA antibodies had an inadequate sensitivity/specificity for children with UC or CD. Those antibodies were not useful for our small number of patients with IC.