Single toxin dose-response models revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demidenko, Eugene, E-mail: eugened@dartmouth.edu

The goal of this paper is to offer a rigorous analysis of the sigmoid shape single toxin dose-response relationship. The toxin efficacy function is introduced and four special points, including maximum toxin efficacy and inflection points, on the dose-response curve are defined. The special points define three phases of the toxin effect on mortality: (1) toxin concentrations smaller than the first inflection point or (2) larger then the second inflection point imply low mortality rate, and (3) concentrations between the first and the second inflection points imply high mortality rate. Probabilistic interpretation and mathematical analysis for each of the fourmore » models, Hill, logit, probit, and Weibull is provided. Two general model extensions are introduced: (1) the multi-target hit model that accounts for the existence of several vital receptors affected by the toxin, and (2) model with a nonzero mortality at zero concentration to account for natural mortality. Special attention is given to statistical estimation in the framework of the generalized linear model with the binomial dependent variable as the mortality count in each experiment, contrary to the widespread nonlinear regression treating the mortality rate as continuous variable. The models are illustrated using standard EPA Daphnia acute (48 h) toxicity tests with mortality as a function of NiCl or CuSO{sub 4} toxin. - Highlights: • The paper offers a rigorous study of a sigmoid dose-response relationship. • The concentration with highest mortality rate is rigorously defined. • A table with four special points for five morality curves is presented. • Two new sigmoid dose-response models have been introduced. • The generalized linear model is advocated for estimation of sigmoid dose-response relationship.« less

Method, system, and computer-readable medium for determining performance characteristics of an object undergoing one or more arbitrary aging conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gering, Kevin L.

A method, system, and computer-readable medium are described for characterizing performance loss of an object undergoing an arbitrary aging condition. Baseline aging data may be collected from the object for at least one known baseline aging condition over time, determining baseline multiple sigmoid model parameters from the baseline data, and performance loss of the object may be determined over time through multiple sigmoid model parameters associated with the object undergoing the arbitrary aging condition using a differential deviation-from-baseline approach from the baseline multiple sigmoid model parameters. The system may include an object, monitoring hardware configured to sample performance characteristics ofmore » the object, and a processor coupled to the monitoring hardware. The processor is configured to determine performance loss for the arbitrary aging condition from a comparison of the performance characteristics of the object deviating from baseline performance characteristics associated with a baseline aging condition.« less

Study of Three-dimensional Magnetic Structure and the Successive Eruptive Nature of Active Region 12371

NASA Astrophysics Data System (ADS)

Vemareddy, P.; Demóulin, P.

2018-04-01

We study the magnetic structure of a successively erupting sigmoid in active region 12371 by modeling the quasi-static coronal field evolution with nonlinear force-free field (NLFFF) equilibria. Helioseismic and Magnetic Imager/Solar Dynamic Observatory vector magnetograms are used as input to the NLFFF model. In all eruption events, the modeled structure resembles the observed pre-eruptive coronal sigmoid and the NLFFF core field is a combination of double inverse-J-shaped and inverse-S field lines with dips touching the photosphere. Such field lines are formed by the flux cancellation reconnection of opposite-J field lines at bald-patch locations, which in turn implies the formation of a weakly twisted flux-rope (FR) from large-scale sheared arcade field lines. Later on, this FR undergoes coronal tether-cutting reconnection until a coronal mass ejection is triggered. The modeled structure captured these major features of sigmoid-to-arcade-to-sigmoid transformation, which is reoccuring under continuous photospheric flux motions. Calculations of the field line twist reveal a fractional increase followed by a decrease of the number of pixels having a range of twist. This traces the buildup process of a twisted core field by slow photospheric motions and the relaxation after eruption, respectively. Our study infers that the large eruptivity of this AR is due to a steep decrease of the background coronal field meeting the torus instability criteria at a low height (≈40 Mm) in contrast to noneruptive ARs.

Use of a generalized sigmoid growth function to predict site index for unmanaged loblolly and slash pine plantations in East Texas

Treesearch

Dean W. Coble; Young-Jin Lee

2006-01-01

A generalized sigmoid growth function was used in this study to model site index (SI) for unmanaged or lowintensity managed loblolly pine (Pinus taeda, L.) and slash pine (Pinus elliottii, Engelm.) plantations in east Texas. Schnute's growth function was fit to 11,367 and 5,040 height-age observations of loblolly and slash...

[Manufacture and application of laparoscopic extraperitoneal sigmoid colostomy].

PubMed

Jin, Hei-ying; DU, Yong-hong; Wang, Xiao-feng; Yao, Hang; Wu, Kun-lan; Zhang, Bei; Zhang, Jin-hao

2013-10-01

To investigate the safety and feasibility of laparoscopic extraperitoneal sigmoid colostomy. Thirty-six patients with low rectal cancer undergoing laproscopic abdominoperineal resection from July 2011 to July 2012 were prospectively enrolled in the study and randomly divided into extraperitoneal colostomy group(EPC, n=18) and internal peritoneal colostomy group(IPC, n=18). Follow-up period was 4-16 (median, 7) months and postoperative complications were compared between two groups. One case in EPC group was converted to IPC because of poor blood supply of the proximal sigmoid, who was eliminated from the subsequent analysis. Compared with the IPC group, the surgery time was longer in EPC group [(25.3±8.5) min vs. (14.7±6.4) min], while the difference was not statistically significant(P>0.05). Each group had 1 case of stoma ischemia, who both received the colostomy reconstructive surgery. The incidence of stoma edema was significantly higher in EPC group[35.3%(6/17) vs. 0, P<0.05). The early postoperative complications rate did not significantly different between the two groups[58.8%(10/17) vs. 27.8%(5/18), P>0.05]. The late postoperative complications rate was 22.2%(4/18) in IPC group, including 1 case of stoma prolapse, 1 case of stoma stenosis and 2 cases of parastomal hernia. No later postoperative complication occurred in EPC group. Extraperitoneal sigmoid colostomy is an easy and safe procedure with lower late complications as compared to internal peritoneal sigmoid colostomy.

Sigmoid function based integral-derivative observer and application to autopilot design

NASA Astrophysics Data System (ADS)

Shao, Xingling; Wang, Honglun; Liu, Jun; Tang, Jun; Li, Jie; Zhang, Xiaoming; Shen, Chong

2017-02-01

To handle problems of accurate signal reconstruction and controller implementation with integral and derivative components in the presence of noisy measurement, motivated by the design principle of sigmoid function based tracking differentiator and nonlinear continuous integral-derivative observer, a novel integral-derivative observer (SIDO) using sigmoid function is developed. The key merit of the proposed SIDO is that it can simultaneously provide continuous integral and differential estimates with almost no drift phenomena and chattering effect, as well as acceptable noise-tolerance performance from output measurement, and the stability is established based on exponential stability and singular perturbation theory. In addition, the effectiveness of SIDO in suppressing drift phenomena and high frequency noises is firstly revealed using describing function and confirmed through simulation comparisons. Finally, the theoretical results on SIDO are demonstrated with application to autopilot design: 1) the integral and tracking estimates are extracted from the sensed pitch angular rate contaminated by nonwhite noises in feedback loop, 2) the PID(proportional-integral-derivative) based attitude controller is realized by adopting the error estimates offered by SIDO instead of using the ideal integral and derivative operator to achieve satisfactory tracking performance under control constraint.

The role of enzyme and substrate concentration in the evaluation of serum angiotensin converting enzyme (ACE) inhibition by enalaprilat in vitro.

PubMed

Weisser, K; Schloos, J

1991-10-09

The relationship between serum angiotensin converting enzyme (ACE) activity and concentration of the ACE inhibitor enalaprilat was determined in vitro in the presence of different concentrations (S = 4-200 mM) of the substrate Hip-Gly-Gly. From Henderson plots, a competitive tight-binding relationship between enalaprilat and serum ACE was found yielding a value of approximately 5 nM for serum ACE concentration (Et) and an inhibition constant (Ki) for enalaprilat of approximately 0.1 nM. A plot of reaction velocity (Vi) versus total inhibitor concentration (It) exhibited a non-parallel shift of the inhibition curve to the right with increasing S. This was reflected by apparent Hill coefficients greater than 1 when the commonly used inhibitory sigmoid concentration-effect model (Emax model) was applied to the data. Slopes greater than 1 were obviously due to discrepancies between the free inhibitor concentration (If) present in the assay and It plotted on the abscissa and could, therefore, be indicators of tight-binding conditions. Thus, the sigmoid Emax model leads to an overestimation of Ki. Therefore, a modification of the inhibitory sigmoid Emax model (called "Emax tight model") was applied, which accounts for the depletion of If by binding, refers to It and allows estimation of the parameters Et and IC50f (free concentration of inhibitor when 50% inhibition occurs) using non-linear regression analysis. This model could describe the non-symmetrical shape of the inhibition curves and the results for Ki and Et correlated very well with those derived from the Henderson plots. The latter findings confirm that the degree of ACE inhibition measured in vitro is, in fact, dependent on the concentration of substrate and enzyme present in the assay. This is of importance not only for the correct evaluation of Ki but also for the interpretation of the time course of serum ACE inhibition measured ex vivo. The non-linear model has some advantages over the linear Henderson equation: it is directly applicable without conversion of the data and avoids the stochastic dependency of the variables, allowing non-linear regression of all data points contributing with the same weight.

Sigmoid colon morphology in the population groups of Durban, South Africa, with special reference to sigmoid volvulus.

PubMed

Madiba, T E; Haffajee, M R

2011-05-01

Sigmoid volvulus demonstrates geographical, racial, and gender variation. This autopsy study was undertaken to establish morphological differences of the sigmoid colon and its mesocolon in which the length and other characteristics were assessed. A total of 590 cadavers were examined (403 African, 91 Indian, and 96 White). Length and height of the sigmoid colon and mesocolon were significantly longer in Africans, and mesocolon root was significantly narrower in Africans. Mesocolic ratio for Africans, Indians, and Whites was 1.1 ± 0.8, 1.8 ± 0.7, and 1.9 ± 1.0, respectively. Africans had a significantly high incidence of redundant sigmoid colon with the long-narrow type and suprapelvic position predominating (P = 0.003); the opposite applied to the classic type. There was no difference in sigmoid colon length, mesocolon height, and width between males and females in all population groups. Among Africans, the long-narrow type was more common in males, and the classic and long-broad types were more common in females. Splaying of teniae coli and thickening of the mesentery were more common in Africans. Tethering of the sigmoid colon to the posterior abdominal wall was less common in Africans compared with other population groups. In conclusion, the sigmoid colon was longer, and the sigmoid mesocolon root was narrower in Africans compared with the other population groups, and the sigmoid colon had a suprapelvic disposition among Africans. In Africans, the sigmoid colon was longer in males with a long-narrow shape. These differences may explain geographical and racial differences in sigmoid volvulus. Copyright © 2011 Wiley-Liss, Inc.

Cell edge detection in JPEG2000 wavelet domain - analysis on sigmoid function edge model.

PubMed

Punys, Vytenis; Maknickas, Ramunas

2011-01-01

Big virtual microscopy images (80K x 60K pixels and larger) are usually stored using the JPEG2000 image compression scheme. Diagnostic quantification, based on image analysis, might be faster if performed on compressed data (approx. 20 times less the original amount), representing the coefficients of the wavelet transform. The analysis of possible edge detection without reverse wavelet transform is presented in the paper. Two edge detection methods, suitable for JPEG2000 bi-orthogonal wavelets, are proposed. The methods are adjusted according calculated parameters of sigmoid edge model. The results of model analysis indicate more suitable method for given bi-orthogonal wavelet.

An Augmented Two-Layer Model Captures Nonlinear Analog Spatial Integration Effects in Pyramidal Neuron Dendrites.

PubMed

Jadi, Monika P; Behabadi, Bardia F; Poleg-Polsky, Alon; Schiller, Jackie; Mel, Bartlett W

2014-05-01

In pursuit of the goal to understand and eventually reproduce the diverse functions of the brain, a key challenge lies in reverse engineering the peculiar biology-based "technology" that underlies the brain's remarkable ability to process and store information. The basic building block of the nervous system is the nerve cell, or "neuron," yet after more than 100 years of neurophysiological study and 60 years of modeling, the information processing functions of individual neurons, and the parameters that allow them to engage in so many different types of computation (sensory, motor, mnemonic, executive, etc.) remain poorly understood. In this paper, we review both historical and recent findings that have led to our current understanding of the analog spatial processing capabilities of dendrites, the major input structures of neurons, with a focus on the principal cell type of the neocortex and hippocampus, the pyramidal neuron (PN). We encapsulate our current understanding of PN dendritic integration in an abstract layered model whose spatially sensitive branch-subunits compute multidimensional sigmoidal functions. Unlike the 1-D sigmoids found in conventional neural network models, multidimensional sigmoids allow the cell to implement a rich spectrum of nonlinear modulation effects directly within their dendritic trees.

Treatment of recurrent sigmoid volvulus in Parkinson's disease by percutaneous endoscopic colostomy

PubMed Central

Toebosch, Susan; Tudyka, Vera; Masclee, Ad; Koek, Ger

2012-01-01

The exact aetiology of sigmoid volvulus in Parkinson's disease (PD) remains unclear. A multiplicity of factors may give rise to decreased gastrointestinal function in PD patients. Early recognition and treatment of constipation in PD patients may alter complications like sigmoid volvulus. Treatment of sigmoid volvulus in PD patients does not differ from other patients and involves endoscopic detorsion. If feasible, secondary sigmoidal resection should be performed. However, if the expected surgical morbidity and mortality is unacceptably high or if the patient refuses surgery, percutaneous endoscopic colostomy (PEC) should be considered. We describe an elderly PD patient who presented with sigmoid volvulus. She was treated conservatively with endoscopic detorsion. Surgery was consistently refused by the patient. After recurrence of the sigmoid volvulus a PEC was placed. PMID:23155325

[Laparoscopic resection of the sigmoid colon for the diverticular disease].

PubMed

Vrbenský, L; Simša, J

2013-07-01

Laparoscopic resection of the sigmoid colon for diverticular disease is nowadays a fully accepted alternative to traditional open procedures. The aim of this work is to summarize the indications, advantages and risks of laparoscopic sigmoid resection for diverticular disease. Review of the literature and recent findings concerning the significance of laparoscopic resection for diverticulosis of the sigmoid colon. The article presents the indications, risks, techniques and perioperative care in patients after laparoscopic resection of the sigmoid colon for diverticular disease.

Impact of esophageal flexion level on the surgical outcome in patients with sigmoid esophageal achalasia.

PubMed

Tsuboi, Kazuto; Omura, Nobuo; Yano, Fumiaki; Hoshino, Masato; Yamamoto, Se-Ryung; Akimoto, Shunsuke; Masuda, Takahiro; Kashiwagi, Hideyuki; Yanaga, Katsuhiko

2017-11-01

Esophageal achalasia can be roughly divided into non-sigmoid and sigmoid types. Laparoscopic surgery has been reported to be less than optimally effective for sigmoid type. The aim of this study was to examine the impact of the esophageal flexion level on the clinical condition and surgical outcomes of patients with sigmoid esophageal achalasia. The subjects were 36 patients with sigmoid esophageal achalasia who had been observed for >1 year after surgery. The subjects were divided into sigmoid type (Sg) and advanced sigmoid type (aSg) groups based on the flexion level of the lower esophagus to compare their clinical parameters and surgical outcomes. The Sg and aSg groups included 26 (72%) and 10 subjects, respectively. There were no marked differences in the clinical parameters or surgical outcomes between the two groups. However, the clearance rate calculated using the timed barium esophagogram was lower in the aSg group than in the Sg group. No differences were found in the postoperative symptom scores between the two groups, and both reported a high level of satisfaction. Although laparoscopic surgery for symptoms of sigmoid esophageal achalasia was highly successful regardless of the flexion level, the improvement in esophageal clearance was lower when the flexion level was higher.

Initial treatment of sigmoid volvulous by colonoscopy.

PubMed Central

Starling, J R

1979-01-01

The initial management of acute, nonstrangulated sigmoid volvulous is to attempt proctosigmoidoscopic, rectal tube, or barium enema reduction and evacuation. If unsuccessful emergency surgery is necessary. The flexible colonoscope offers an additional therapeutic modality to effectuate preoperative reduction of the twisted sigmoid colon if attempts with conventional methods fail. Three cases of acute sigmoid volvulous are presented which illustrate for the first time successful reduction of acute sigmoid volvulous by colonoscopy after failure of the usual methods of treatment. Instead of emergency surgery all of these patients had elective resection with primary colocolostomy. Patients with acute sigmoid volvulous refractile to reduction by conventional modalities should have an attempt at flexible colonoscopic reduction. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. PMID:464675

An Augmented Two-Layer Model Captures Nonlinear Analog Spatial Integration Effects in Pyramidal Neuron Dendrites

PubMed Central

JADI, MONIKA P.; BEHABADI, BARDIA F.; POLEG-POLSKY, ALON; SCHILLER, JACKIE; MEL, BARTLETT W.

2014-01-01

In pursuit of the goal to understand and eventually reproduce the diverse functions of the brain, a key challenge lies in reverse engineering the peculiar biology-based “technology” that underlies the brain’s remarkable ability to process and store information. The basic building block of the nervous system is the nerve cell, or “neuron,” yet after more than 100 years of neurophysiological study and 60 years of modeling, the information processing functions of individual neurons, and the parameters that allow them to engage in so many different types of computation (sensory, motor, mnemonic, executive, etc.) remain poorly understood. In this paper, we review both historical and recent findings that have led to our current understanding of the analog spatial processing capabilities of dendrites, the major input structures of neurons, with a focus on the principal cell type of the neocortex and hippocampus, the pyramidal neuron (PN). We encapsulate our current understanding of PN dendritic integration in an abstract layered model whose spatially sensitive branch-subunits compute multidimensional sigmoidal functions. Unlike the 1-D sigmoids found in conventional neural network models, multidimensional sigmoids allow the cell to implement a rich spectrum of nonlinear modulation effects directly within their dendritic trees. PMID:25554708

Intramural distribution of regulatory peptides in the sigmoid-recto-anal region of the human gut.

PubMed

Ferri, G L; Adrian, T E; Allen, J M; Soimero, L; Cancellieri, A; Yeats, J C; Blank, M; Polak, J M; Bloom, S R

1988-06-01

The distribution of regulatory peptides was studied in the separated mucosa, submucosa and muscularis externa taken at 10 sampling sites encompassing the whole human sigmoid colon (five sites), rectum (two sites), and anal canal (three sites). Consistently high concentrations of VIP were measured in the muscle layer at most sites (proximal sigmoid: 286 (16) pmol/g, upper rectum: 269 (17), a moderate decrease being found in the distal smooth sphincter (151 (30) pmol/g). Values are expressed as mean (SE). Conversely, substance P concentrations showed an obvious decline in the recto-anal muscle (mid sigmoid: 19 (2.0) pmol/g, distal rectum: 7.1 (1.3), upper anal canal: 1.6 (0.6)). Somatostatin was mainly present in the sigmoid mucosa and submucosa (37 (9.3) and 15 (3.5) pmol/g, respectively) and showed low, but consistent concentrations in the muscle (mid sigmoid: 2.2 (0.7) pmol/g, upper anal canal: 1.5 (0.8]. Starting in the distal sigmoid colon, a distinct peak of tissue NPY was revealed, which was most striking in the muscle (of mid sigmoid: 16 (3.9) pmol/g, upper rectum: 47 (7.8), anal sphincter: 58 (14)). Peptide YY was confined to the mucosa and showed an earlier peak (upper sigmoid: 709 (186) pmol/g, mid-distal sigmoid: 1965 (484)). A clear differential distribution of regulatory peptides was thus shown in the region studied. A possible role is suggested for NPY and VIP containing nerves in the effector control of the human internal anal sphincter.

Intramural distribution of regulatory peptides in the sigmoid-recto-anal region of the human gut.

PubMed Central

Ferri, G L; Adrian, T E; Allen, J M; Soimero, L; Cancellieri, A; Yeats, J C; Blank, M; Polak, J M; Bloom, S R

1988-01-01

The distribution of regulatory peptides was studied in the separated mucosa, submucosa and muscularis externa taken at 10 sampling sites encompassing the whole human sigmoid colon (five sites), rectum (two sites), and anal canal (three sites). Consistently high concentrations of VIP were measured in the muscle layer at most sites (proximal sigmoid: 286 (16) pmol/g, upper rectum: 269 (17), a moderate decrease being found in the distal smooth sphincter (151 (30) pmol/g). Values are expressed as mean (SE). Conversely, substance P concentrations showed an obvious decline in the recto-anal muscle (mid sigmoid: 19 (2.0) pmol/g, distal rectum: 7.1 (1.3), upper anal canal: 1.6 (0.6)). Somatostatin was mainly present in the sigmoid mucosa and submucosa (37 (9.3) and 15 (3.5) pmol/g, respectively) and showed low, but consistent concentrations in the muscle (mid sigmoid: 2.2 (0.7) pmol/g, upper anal canal: 1.5 (0.8]. Starting in the distal sigmoid colon, a distinct peak of tissue NPY was revealed, which was most striking in the muscle (of mid sigmoid: 16 (3.9) pmol/g, upper rectum: 47 (7.8), anal sphincter: 58 (14)). Peptide YY was confined to the mucosa and showed an earlier peak (upper sigmoid: 709 (186) pmol/g, mid-distal sigmoid: 1965 (484)). A clear differential distribution of regulatory peptides was thus shown in the region studied. A possible role is suggested for NPY and VIP containing nerves in the effector control of the human internal anal sphincter. PMID:2454876

Enviromental influences on the {sup 137}Cs kinetics of the yellow-bellied turtle (Trachemys Scripta)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peters, E.L.; Brisbin, L.I. Jr.

1996-02-01

Assessments of ecological risk require accurate predictions of contaminant dynamics in natural populations. However, simple deterministic models that assume constant uptake rates and elimination fractions may compromise both their ecological realism and their general application to animals with variable metabolism or diets. In particular, the temperature-dependent model of metabolic rates characteristic of ectotherms may lead to significant differences between observed and predicted contaminant kinetics. We examined the influence of a seasonally variable thermal environment on predicting the uptake and annual cycling of contaminants by ectotherms, using a temperature-dependent model of {sup 137}Cs kinetics in free-living yellow-bellied turtles, Trachemys scripta. Wemore » compared predictions from this model with those of deterministics negative exponential and flexibly shaped Richards sigmoidal models. Concentrations of {sup 137}Cs in a population if this species in Pond B, a radionuclide-contaminated nuclear reactor cooling reservoir, and {sup 137}Cs uptake by the uncontaminated turtles held captive in Pond B for 4 yr confirmed both the pattern of uptake and the equilibrium concentrations predicted by the temperature-dependent model. Almost 90% of the variance on the predicted time-integrated {sup 137}Cs concentration was explainable by linear relationships with model paramaters. The model was also relatively insensitive to uncertainties in the estimates of ambient temperature, suggesting that adequate estimates of temperature-dependent ingestion and elimination may require relatively few measurements of ambient conditions at sites of interest. Analyses of Richards sigmoidal models of {sup 137}Cs uptake indicated significant differences from a negative exponential trajectory in the 1st yr after the turtles` release into Pond B. 76 refs., 7 figs., 5 tabs.« less

Rupture of sigmoid colon caused by compressed air.

PubMed

Yin, Wan-Bin; Hu, Ji-Lin; Gao, Yuan; Zhang, Xian-Xiang; Zhang, Mao-Shen; Liu, Guang-Wei; Zheng, Xue-Feng; Lu, Yun

2016-03-14

Compressed air has been generally used since the beginning of the 20(th) century for various applications. However, rupture of the colon caused by compressed air is uncommon. We report a case of pneumatic rupture of the sigmoid colon. The patient was admitted to the emergency room complaining of abdominal pain and distention. His colleague triggered a compressed air nozzle against his anus as a practical joke 2 h previously. On arrival, his pulse rate was 126 beats/min, respiratory rate was 42 breaths/min and blood pressure was 86/54 mmHg. Physical examination revealed peritoneal irritation and the abdomen was markedly distended. Computed tomography of the abdomen showed a large volume of air in the abdominal cavity. Peritoneocentesis was performed to relieve the tension pneumoperitoneum. Emergency laparotomy was done after controlling shock. Laparotomy revealed a 2-cm perforation in the sigmoid colon. The perforation was sutured and temporary ileostomy was performed as well as thorough drainage and irrigation of the abdominopelvic cavity. Reversal of ileostomy was performed successfully after 3 mo. Follow-up was uneventful. We also present a brief literature review.

Rupture of sigmoid colon caused by compressed air

PubMed Central

Yin, Wan-Bin; Hu, Ji-Lin; Gao, Yuan; Zhang, Xian-Xiang; Zhang, Mao-Shen; Liu, Guang-Wei; Zheng, Xue-Feng; Lu, Yun

2016-01-01

Compressed air has been generally used since the beginning of the 20th century for various applications. However, rupture of the colon caused by compressed air is uncommon. We report a case of pneumatic rupture of the sigmoid colon. The patient was admitted to the emergency room complaining of abdominal pain and distention. His colleague triggered a compressed air nozzle against his anus as a practical joke 2 h previously. On arrival, his pulse rate was 126 beats/min, respiratory rate was 42 breaths/min and blood pressure was 86/54 mmHg. Physical examination revealed peritoneal irritation and the abdomen was markedly distended. Computed tomography of the abdomen showed a large volume of air in the abdominal cavity. Peritoneocentesis was performed to relieve the tension pneumoperitoneum. Emergency laparotomy was done after controlling shock. Laparotomy revealed a 2-cm perforation in the sigmoid colon. The perforation was sutured and temporary ileostomy was performed as well as thorough drainage and irrigation of the abdominopelvic cavity. Reversal of ileostomy was performed successfully after 3 mo. Follow-up was uneventful. We also present a brief literature review. PMID:26973403

SigmoID: a user-friendly tool for improving bacterial genome annotation through analysis of transcription control signals

PubMed Central

Damienikan, Aliaksandr U.

2016-01-01

The majority of bacterial genome annotations are currently automated and based on a ‘gene by gene’ approach. Regulatory signals and operon structures are rarely taken into account which often results in incomplete and even incorrect gene function assignments. Here we present SigmoID, a cross-platform (OS X, Linux and Windows) open-source application aiming at simplifying the identification of transcription regulatory sites (promoters, transcription factor binding sites and terminators) in bacterial genomes and providing assistance in correcting annotations in accordance with regulatory information. SigmoID combines a user-friendly graphical interface to well known command line tools with a genome browser for visualising regulatory elements in genomic context. Integrated access to online databases with regulatory information (RegPrecise and RegulonDB) and web-based search engines speeds up genome analysis and simplifies correction of genome annotation. We demonstrate some features of SigmoID by constructing a series of regulatory protein binding site profiles for two groups of bacteria: Soft Rot Enterobacteriaceae (Pectobacterium and Dickeya spp.) and Pseudomonas spp. Furthermore, we inferred over 900 transcription factor binding sites and alternative sigma factor promoters in the annotated genome of Pectobacterium atrosepticum. These regulatory signals control putative transcription units covering about 40% of the P. atrosepticum chromosome. Reviewing the annotation in cases where it didn’t fit with regulatory information allowed us to correct product and gene names for over 300 loci. PMID:27257541

[Sigmoid endometriosis: a diagnostic dilemma on multidetector CT].

PubMed

Telegrafo, Michele; Lorusso, Valentina; Rubini, Giuseppe; Rella, Leonarda; Pezzolla, Angela; Stabile Ianora, Amato Antonio; Moschetta, Marco

2013-01-01

Intestinal endometriosis represents a common condition that occurs particularly in women of reproductive age. The gastrointestinal tract is the third most common localization of endometriosis, after the ovaries and the peritoneum, and recto-sigmoid tract is involved in 70% of cases. Recto-sigmoid endometriosis has to be differentiated from other diseases of large bowel, especially in patients without a history of endometriosis. We report a case of sigmoid endometriosis which represented a diagnostic dilemma on multidetector computed tomography.

Optimal Colostomy Placement in Spinal Cord Injury Patients.

PubMed

Xu, Jiashou; Dharmarajan, Sekhar; Johnson, Frank E

2016-03-01

Barring unusual circumstances, sigmoid colostomy is the optimal technique for management of defecation in spinal cord injury (SCI) patients. We sought to provide evidence that a sigmoid colostomy is not difficult to perform in SCI patients and has better long-term results. The St. Louis Department of Veterans Affairs has a Commission on Accreditation of Rehabilitation Facilities (CARF)-approved SCI Unit. We reviewed the operative notes on all SCI patients who received a colostomy for fecal management by three ASCRS-certified colorectal surgeons at the St. Louis Department of Veterans Affairs from January 1, 2007 to November 26, 2012. There were 27 operations for which the recorded indication for surgery suggested that the primary disorder was SCI. Fourteen had traumatic SCI of the thoracic and/or lumbar spine and were evaluable. Of these 14 patients, 12 had laparoscopic sigmoid colostomy and two had open sigmoid colostomy. We encountered one evaluable patient with a remarkably large amount of retroperitoneal bony debris who successfully underwent laparoscopic sigmoid colostomy. In conclusion, sigmoid colostomy is the consensus optimal procedure for fecal management in SCI patients. Laparoscopic procedures are preferred. Care providers should specify sigmoid colostomy when contacting a surgeon.

The transvaginal hybrid NOTES versus conventionally assisted laparoscopic sigmoid resection for diverticular disease (TRANSVERSAL) trial: study protocol for a randomized controlled trial.

PubMed

Senft, Jonas D; Warschkow, Rene; Diener, Markus K; Tarantino, Ignazio; Steinemann, Daniel C; Lamm, Sebastian; Simon, Thomas; Zerz, Andreas; Müller-Stich, Beat P; Linke, Georg R

2014-11-20

Natural orifice transluminal endoscopic surgery (NOTES) is the consequence of further development of minimally invasive surgery to reduce abdominal incisions and surgical trauma. The potential benefits are expected to be less postoperative pain, faster convalescence, and reduced risk for incisional hernias and wound infections compared to conventional methods. Recent clinical studies have demonstrated the feasibility and safety of transvaginal NOTES, and transvaginal access is currently the most frequent clinically applied route for NOTES procedures. However, despite increasing clinical application, no firm clinical evidence is available for objective assessment of the potential benefits and risks of transvaginal NOTES compared to the current surgical standard. The TRANSVERSAL trial is designed as a randomized controlled trial to compare transvaginal hybrid NOTES and laparoscopic-assisted sigmoid resection. Female patients referred to elective sigmoid resection due to complicated or reoccurring diverticulitis of the sigmoid colon are considered eligible. The primary endpoint will be pain intensity during mobilization 24 hours postoperatively as measured by the blinded patient and blinded assessor on a visual analogue scale (VAS). Secondary outcomes include daily pain intensity and analgesic use, patient mobility, intraoperative complications, morbidity, length of stay, quality of life, and sexual function. Follow-up visits are scheduled 3, 12, and 36 months after surgery. A total sample size of 58 patients was determined for the analysis of the primary endpoint. The confirmatory analysis will be performed based on the intention-to-treat (ITT) principle. The TRANSVERSAL trial is the first study to compare transvaginal hybrid NOTES and conventionally assisted laparoscopic surgery for colonic resection in a randomized controlled setting. The results of the TRANSVERSAL trial will allow objective assessment of the potential benefits and risks of NOTES compared to the current surgical standard for sigmoid resection. The trial protocol was registered in the German Clinical Trials Register ( DRKS00005995) on March 27, 2014.

Hemorrhagic shock caused by sigmoid colon volvulus: An autopsy case

PubMed Central

Sato, Hiroaki; Tanaka, Toshiko; Tanaka, Noriyuki

2011-01-01

Summary Background Many reports have described sigmoid volvulus, but fatal hemorrhagic shock resulting from the rupture of the involved artery has not been reported as a complication of a sigmoid volvulus. Case Report A 71-year-old man with slight abdominal pain and obstipation in hypotension died at a nursing home without seeing a doctor. At autopsy, a mesenteric hematoma and hemoperitoneum was observed with approximately 1,000 ml of blood in the abdominal cavity. The sigmoid colon and the mesentery were twisted at an adhesion site of a sigmoid colon to an ileum, and the condition was determined to be a sigmoid volvulus. The volvulus was observed to be loosened. The inferior mesenteric artery was incorporated into the twisted part of the mesentery, but remained patent, and its peripheral branch near the hematoma ruptured without histological abnormality. Conclusions Since ischemic-reperfusion injury occurs with a temporarily occluded artery, the acute re-loading of blood flow may injure the distal vessels after spontaneous reduction of compression by loosening of the volvulus. PMID:22129905

Sigmoid volvulus in an adolescent girl: staged management with emergency colonoscopic reduction and decompression followed by elective sigmoid colectomy

PubMed Central

Patel, Ramnik V; Njere, Ike; Campbell, Alison; Daniel, Rejoo; Azaz, Amer; Fleet, Mahmud

2014-01-01

A case of acute sigmoid volvulus in a 14-year-old adolescent girl presenting with acute low large bowel obstruction with a background of chronic constipation has been presented. Abdominal radiograph and CT scan helped in diagnosis. She underwent emergency colonoscopic detorsion and decompression uneventfully. Lower gastrointestinal contrast study showed very redundant sigmoid colonic loop without any transition zone and she subsequently underwent elective sigmoid colectomy with good outcome. The sigmoid volvulus should be considered in the differential diagnosis of paediatric acute abdomen presenting with marked abdominal distention, absolute constipation and pain but without vomiting. Plain abdominal radiograph and the CT scan are helpful to confirm the diagnosis. Early colonoscopic detorsion and decompression allows direct visualisation of the vascular compromise, assessment of band width of the volvulus and can reduce complications and mortality. Associated Hirschsprung's disease should be suspected if clinical and radiological features are suggestive in which case a rectal biopsy before definitive surgery should be considered. PMID:25143313

Sigmoid volvulus in an adolescent girl: staged management with emergency colonoscopic reduction and decompression followed by elective sigmoid colectomy.

PubMed

Patel, Ramnik V; Njere, Ike; Campbell, Alison; Daniel, Rejoo; Azaz, Amer; Fleet, Mahmud

2014-08-20

A case of acute sigmoid volvulus in a 14-year-old adolescent girl presenting with acute low large bowel obstruction with a background of chronic constipation has been presented. Abdominal radiograph and CT scan helped in diagnosis. She underwent emergency colonoscopic detorsion and decompression uneventfully. Lower gastrointestinal contrast study showed very redundant sigmoid colonic loop without any transition zone and she subsequently underwent elective sigmoid colectomy with good outcome. The sigmoid volvulus should be considered in the differential diagnosis of paediatric acute abdomen presenting with marked abdominal distention, absolute constipation and pain but without vomiting. Plain abdominal radiograph and the CT scan are helpful to confirm the diagnosis. Early colonoscopic detorsion and decompression allows direct visualisation of the vascular compromise, assessment of band width of the volvulus and can reduce complications and mortality. Associated Hirschsprung's disease should be suspected if clinical and radiological features are suggestive in which case a rectal biopsy before definitive surgery should be considered. 2014 BMJ Publishing Group Ltd.

Application of the Artificial Neural Network model for prediction of monthly Standardized Precipitation and Evapotranspiration Index using hydrometeorological parameters and climate indices in eastern Australia

NASA Astrophysics Data System (ADS)

Deo, Ravinesh C.; Şahin, Mehmet

2015-07-01

The forecasting of drought based on cumulative influence of rainfall, temperature and evaporation is greatly beneficial for mitigating adverse consequences on water-sensitive sectors such as agriculture, ecosystems, wildlife, tourism, recreation, crop health and hydrologic engineering. Predictive models of drought indices help in assessing water scarcity situations, drought identification and severity characterization. In this paper, we tested the feasibility of the Artificial Neural Network (ANN) as a data-driven model for predicting the monthly Standardized Precipitation and Evapotranspiration Index (SPEI) for eight candidate stations in eastern Australia using predictive variable data from 1915 to 2005 (training) and simulated data for the period 2006-2012. The predictive variables were: monthly rainfall totals, mean temperature, minimum temperature, maximum temperature and evapotranspiration, which were supplemented by large-scale climate indices (Southern Oscillation Index, Pacific Decadal Oscillation, Southern Annular Mode and Indian Ocean Dipole) and the Sea Surface Temperatures (Nino 3.0, 3.4 and 4.0). A total of 30 ANN models were developed with 3-layer ANN networks. To determine the best combination of learning algorithms, hidden transfer and output functions of the optimum model, the Levenberg-Marquardt and Broyden-Fletcher-Goldfarb-Shanno (BFGS) quasi-Newton backpropagation algorithms were utilized to train the network, tangent and logarithmic sigmoid equations used as the activation functions and the linear, logarithmic and tangent sigmoid equations used as the output function. The best ANN architecture had 18 input neurons, 43 hidden neurons and 1 output neuron, trained using the Levenberg-Marquardt learning algorithm using tangent sigmoid equation as the activation and output functions. An evaluation of the model performance based on statistical rules yielded time-averaged Coefficient of Determination, Root Mean Squared Error and the Mean Absolute Error ranging from 0.9945-0.9990, 0.0466-0.1117, and 0.0013-0.0130, respectively for individual stations. Also, the Willmott's Index of Agreement and the Nash-Sutcliffe Coefficient of Efficiency were between 0.932-0.959 and 0.977-0.998, respectively. When checked for the severity (S), duration (D) and peak intensity (I) of drought events determined from the simulated and observed SPEI, differences in drought parameters ranged from - 1.41-0.64%, - 2.17-1.92% and - 3.21-1.21%, respectively. Based on performance evaluation measures, we aver that the Artificial Neural Network model is a useful data-driven tool for forecasting monthly SPEI and its drought-related properties in the region of study.

Bacterial flora of the sigmoid neovagina.

PubMed Central

Toolenaar, T A; Freundt, I; Wagenvoort, J H; Huikeshoven, F J; Vogel, M; Jeekel, H; Drogendijk, A C

1993-01-01

The bacterial microbiota of 15 sigmoid neovaginas, created in patients with congenital vaginal aplasia or male transsexualism, was studied. No specimen was sterile, and only normal inhabitants of the colon were cultured. The total counts of bacteria were lower than those reported for healthy sigmoid colons. PMID:8308126

RIGHT AND LEFT VENTRICULAR DIASTOLIC PRESSURE–VOLUME RELATIONS: A COMPREHENSIVE REVIEW

PubMed Central

Pasipoularides, Ares

2012-01-01

Ventricular compliance alterations can affect cardiac performance and adaptations. Moreover, diastolic mechanics are important in assessing both diastolic and systolic function, since any filling impairment can compromise systolic function. A sigmoidal passive filling pressure-volume relationship, developed using chronically instrumented, awake-animal disease models, is clinically adaptable to evaluating diastolic dynamics using subject-specific micromanometric and volumetric data from the entire filling period of any heartbeat(s). This innovative relationship is the global, integrated expression of chamber geometry, wall thickness, and passive myocardial wall properties. Chamber and myocardial compliance curves of both ventricles can be computed by the sigmoidal methodology over the entire filling period and plotted over appropriate filling pressure ranges. Important characteristics of the compliance curves can be examined and compared between the right and the left ventricle, and for different physiological and pathological conditions. The sigmoidal paradigm is more accurate and, therefore, a better alternative to the conventional exponential pressure-volume approximation. PMID:23179133

Prospective randomized comparison of laparoscopic peritoneal vaginoplasty with laparoscopic sigmoid vaginoplasty for treating congenital vaginal agenesis.

PubMed

Cao, Lili; Wang, Yanzhou; Li, Yudi; Xu, Huicheng

2013-07-01

The aim of this study was to compare the effectiveness and long-term anatomic and functional results of laparoscopic peritoneal vaginoplasty and laparoscopic sigmoid vaginoplasty. From January 2002 to December 2010, 40 patients with congenital vaginal agenesis were prospectively randomized to undergo either laparoscopic peritoneal vaginoplasty (26 cases) or laparoscopic sigmoid vaginoplasty (14 cases) in 2:1 ratio. Pre- and postoperative examination findings, Female Sexual Function Index (FSFI) questionnaire responses, and sexual satisfaction rates are reported. All surgical procedures were performed successfully, with no intraoperative complications. The laparoscopic peritoneal vaginoplasty group had significantly less blood loss and a surgery shorter on average than the laparoscopic sigmoid colovaginoplasty group. Postoperative course was uneventful for all patients in both groups, though postoperative retention time and hospital stay were less for peritoneal vaginoplasty patients than for sigmoid vaginoplasty patients. Mean neovaginal length, excessive mucous production, sexual life initiation time, and sexual satisfaction rate were similar between groups. Patient complaints of abdominal discomfort, unusual odor from vaginal secretions, and vaginal contraction during intercourse were higher in the sigmoid colovaginoplasty group (p < 0.005 vs. peritoneal vaginoplasty). Postoperative FSFI scores did not differ significantly between groups. Relative to laparoscopic sigmoid colovaginoplasty, laparoscopic peritoneal vaginoplasty provides good anatomic and functional results and excellent patient satisfaction.

Trautmann's triangle anatomy with application to posterior transpetrosal and other related skull base procedures.

PubMed

Tubbs, R Shane; Griessenauer, Christoph; Loukas, Marios; Ansari, Shaheryar F; Fritsch, Michael H; Cohen-Gadol, Aaron A

2014-10-01

Trautmann's triangle (TT) faces the cerebellopontine angle and is exposed during posterior transpetrosal approaches. However, reports on the morphometric analysis of this structure are lacking in the literature. The goal was to better understand this important operative corridor. TT was exposed from an external approach (transmastoid) in ten cadavers (20 sides) and from an internal approach on 20 dry adult temporal bones. Measurements included calculation of the area of TT and the distance of the endolymphatic sac from the anterior border of the sigmoid sinus. The area range of TT was 45-210 mm(2) (mean 151 mm(2); SD 37 mm(2)). Three types of triangles were identified based on area. Type I triangles had areas less than 75 mm(2), Type II areas were 75-149 mm(2), and Type III areas were 150 mm(2) and greater. These types were observed in 37.5%, 35%, and 27.5% of sides, respectively. The distance from the jugular bulb's anterior border to the posterior border of the posterior semicircular canal ranged from 6 to 11 mm (mean 8.5 mm). The endolymphatic sac was located in the inferior portion of TT and traveled anterior to the sigmoid sinus. The horizontal distance from the anterior edge of the sigmoid sinus to the posterior edge of the endolymphatic sac ranged from 0 to 13.5 mm (mean 9 mm). Additional anatomic knowledge regarding TT may improve neurosurgical procedures in this region by avoiding intrusion into the endolymphatic sac and sigmoid sinus. © 2014 Wiley Periodicals, Inc.

Novel Approach to Treat Uncomplicated Sigmoid Volvulus Combining Minimally Invasive Surgery with Enhanced Recovery, in a Rural Hospital in Zambia.

PubMed

van der Naald, Niels; Prins, Marloes I; Otten, Kars; Kumwenda, Dayson; Bleichrodt, Robert P

2018-06-01

In sub-Saharan Africa, sigmoid volvulus is a frequent cause of bowel obstruction. The aim of this study was to evaluate the results of acute sigmoid resection and anastomosis via a mini-laparotomy in patients with uncomplicated sigmoid volvulus, following the principles of "Enhanced Recovery After Surgery (ERAS)", in a low-resource setting. Patients with uncomplicated sigmoid volvulus were operated acutely, via a mini-laparotomy, according to the principles of ERAS. Intraoperative complications, duration of operation, morbidity, mortality and length of hospital stay were evaluated, retrospectively. From 1 March 2012 to 1 September 2017, 31 consecutive patients were treated with acute sigmoid resection and anastomosis, via a mini-laparotomy. There were 29 men and 2 women, median age 57 (range 17-92) years. Patients were operated after a median period of 4 (range 1.5-18) hours. The median duration of the operative procedure was 50 (range 30-105) minutes. Two patients died (6.3%). One patient died during an uncomplicated operation. The cause of death is unknown. One patient with a newly diagnosed HIV infection had an anastomotic dehiscence. After Hartmann's procedure, he died on the 17th post-operative day as a result of a HIV-related double-sided pneumonia, without signs of abdominal sepsis. One patient had an urinary retention and 1 patient haematuria after bladder catheter insertion. Acute sigmoid resection and primary anastomosis via a mini-laparotomy for uncomplicated sigmoid volvulus, without preoperative endoscopic decompression is a safe procedure with a low morbidity and mortality.

Venous sinus compromise after pre-sigmoid, transpetrosal approach for skull base tumors: A study on the asymptomatic incidence and report of a rare dural arteriovenous fistula as symptomatic manifestation.

PubMed

Jean, Walter C; Felbaum, Daniel R; Stemer, Andrew B; Hoa, Michael; Kim, H Jeffrey

2017-05-01

The sigmoid sinus is routinely exposed and manipulated during pre-sigmoid, transpetrosal approaches to the skull base, but there is scant data available on the incidence of venous sinus compromise after surgery. We encountered a dural arteriovenous fistula as a result of sigmoid sinus occlusion and examined the incidence of venous sinus thrombosis or narrowing after transpetrosal surgeries. We performed a retrospective analysis of a series of patients treated by the senior surgeons (WCJ, MH, HJK), who underwent either a posterior petrosectomy or translabyrinthine approach for various skull base tumors. All available clinical and radiographic data were thoroughly examined in each patient to determine the post-operative fate of the venous sinuses. Of the 52 available patients, five patients were discovered post-operatively to have a narrowed or constricted sigmoid sinus ipsilateral to the surgery, whereas another five patients were diagnosed with asymptomatic sinus thrombosis either in the transverse or sigmoid or both. None of these patients experienced symptoms, nor were there any instance of ischemic or hemorrhagic complications. However, there was one additional patient who presented with pulsatile tinnitus 2years after surgery. His angiogram showed an occlusion of the ipsilateral sigmoid sinus and a posterior fossa dural arteriovenous fistula. A two-stage transvenous and transarterial embolization was successful in eliminating the fistula. Technical considerations to avoid sinus injuries during pre-sigmoid, transpetrosal surgery are discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Diagnosis of a sigmoid volvulus in pregnancy: ultrasonography and magnetic resonance imaging findings

PubMed Central

Palmucci, Stefano; Lanza, Maria Letizia; Gulino, Fabrizio; Scilletta, Beniamino; Ettorre, Giovanni Carlo

2014-01-01

Sigmoid volvulus complicating pregnancy is a rare, non-obstetric cause of abdominal pain that requires prompt surgical intervention (decompression) to avoid intestinal ischemia and perforation. We report the case of a 31-week pregnant woman with abdominal pain and subsequent development of constipation. Preoperative diagnosis was achieved using magnetic resonance imaging and ultrasonography: the large bowel distension and a typical whirl sign - near a sigmoid colon transition point - suggested the diagnosis of sigmoid volvulus. The decision to refer the patient for emergency laparotomy was adopted without any ionizing radiation exposure, and the pre-operative diagnosis was confirmed after surgery. Imaging features of sigmoid volvulus and differential diagnosis from other non-obstetric abdominal emergencies in pregnancy are discussed in our report, with special emphasis on the diagnostic capabilities of ultrasonography and magnetic resonance imaging. PMID:24967020

Diagnosis of a sigmoid volvulus in pregnancy: ultrasonography and magnetic resonance imaging findings.

PubMed

Palmucci, Stefano; Lanza, Maria Letizia; Gulino, Fabrizio; Scilletta, Beniamino; Ettorre, Giovanni Carlo

2014-02-01

Sigmoid volvulus complicating pregnancy is a rare, non-obstetric cause of abdominal pain that requires prompt surgical intervention (decompression) to avoid intestinal ischemia and perforation. We report the case of a 31-week pregnant woman with abdominal pain and subsequent development of constipation. Preoperative diagnosis was achieved using magnetic resonance imaging and ultrasonography: the large bowel distension and a typical whirl sign - near a sigmoid colon transition point - suggested the diagnosis of sigmoid volvulus. The decision to refer the patient for emergency laparotomy was adopted without any ionizing radiation exposure, and the pre-operative diagnosis was confirmed after surgery. Imaging features of sigmoid volvulus and differential diagnosis from other non-obstetric abdominal emergencies in pregnancy are discussed in our report, with special emphasis on the diagnostic capabilities of ultrasonography and magnetic resonance imaging.

Percutaneous Endoscopic Colostomy: A New Technique for the Treatment of Recurrent Sigmoid Volvulus

PubMed Central

Al-Alawi, Ibrahim K.

2010-01-01

Sigmoid volvulus is a common cause of large bowel obstruction in western countries and Africa. It accounts for 25% of the patients admitted to the hospital for large bowel obstruction. The acute management of sigmoid volvulus is sigmoidoscopic decompression. However, the recurrence rate can be as high as 60% in some series. Recurrent sigmoid volvulus in elderly patients who are not fit for definitive surgery is difficult to manage. The percutaneous endoscopic placement of two percutaneous endoscopic colostomy tube placement is a simple and relatively safe procedure. The two tubes should be left open to act as vents for the colon from over-distending. In our opinion, this aspect is key to its success as it keeps the sigmoid colon deflated until adhesions form between the colon and the abdominal wall. PMID:20339184

Sigmoid Sinus Diverticulum, Dehiscence, and Venous Sinus Stenosis: Potential Causes of Pulsatile Tinnitus in Patients with Idiopathic Intracranial Hypertension?

PubMed

Lansley, J A; Tucker, W; Eriksen, M R; Riordan-Eva, P; Connor, S E J

2017-09-01

Pulsatile tinnitus is experienced by most patients with idiopathic intracranial hypertension. The pathophysiology remains uncertain; however, transverse sinus stenosis and sigmoid sinus diverticulum/dehiscence have been proposed as potential etiologies. We aimed to determine whether the prevalence of transverse sinus stenosis and sigmoid sinus diverticulum/dehiscence was increased in patients with idiopathic intracranial hypertension and pulsatile tinnitus relative to those without pulsatile tinnitus and a control group. CT vascular studies of patients with idiopathic intracranial hypertension with pulsatile tinnitus ( n = 42), without pulsatile tinnitus ( n = 37), and controls ( n = 75) were independently reviewed for the presence of severe transverse sinus stenosis and sigmoid sinus diverticulum/dehiscence according to published criteria. The prevalence of transverse sinus stenosis and sigmoid sinus diverticulum/dehiscence in patients with idiopathic intracranial hypertension with pulsatile tinnitus was compared with that in the nonpulsatile tinnitus idiopathic intracranial hypertension group and the control group. Further comparisons included differing degrees of transverse sinus stenosis (50% and 75%), laterality of transverse sinus stenosis/sigmoid sinus diverticulum/dehiscence, and ipsilateral transverse sinus stenosis combined with sigmoid sinus diverticulum/dehiscence. Severe bilateral transverse sinus stenoses were more frequent in patients with idiopathic intracranial hypertension than in controls ( P < .001), but there was no significant association between transverse sinus stenosis and pulsatile tinnitus within the idiopathic intracranial hypertension group. Sigmoid sinus dehiscence (right- or left-sided) was also more common in patients with idiopathic intracranial hypertension compared with controls ( P = .01), but there was no significant association with pulsatile tinnitus within the idiopathic intracranial hypertension group. While our data corroborate previous studies demonstrating increased prevalence of sigmoid sinus diverticulum/dehiscence and transverse sinus stenosis in idiopathic intracranial hypertension, we did not establish an increased prevalence in patients with idiopathic intracranial hypertension with pulsatile tinnitus compared with those without. It is therefore unlikely that these entities represent a direct structural correlate of pulsatile tinnitus in patients with idiopathic intracranial hypertension. © 2017 by American Journal of Neuroradiology.

The Relation of Smoking, Alcohol Use and Obesity to Risk of Sigmoid Colon and Rectal Adenomas

PubMed Central

Kono, Suminori; Shinchi, Koichi; Wakabayashi, Kazuo; Todoroki, Isao; Sakurai, Yutaka; Imanishi, Koji; Nishikawa, Hiroshi; Ogawa, Shinsaku; Katsurada, Mitsuhiko

1995-01-01

We conducted a case‐control study, using 429 cases with histologically confirmed sigmoid adenoma, 75 cases with rectal adenoma, and 3101 controls showing normal colonoscopy at least up to 60 cm from the anus. The subjects were male Self‐Defense Forces personnel aged 48–56 who received a retirement health examination including a routine sigmoid‐ or colonoscopy. Lifestyle characteristics were ascertained by a self‐administered questionnaire. Smoking in the recent past (ġ 10 years preceding the colonoscopy) and smoking in the remote past (>10 years before the colonoscopy) were both significantly associated with risk of sigmoid adenoma but not with rectal adenoma as a whole. After reciprocal adjustment for smoking in the two periods, only smoking in the recent past was associated with both sigmoid colon and rectal adenomas. Odds ratios (OR) of sigmoid adenoma (and 95% confidence interval) for the categories of 0, 1‐150, 151‐250 and ġ251 cigarette‐years were 1.0 (reference), 1.9 (1.3‐2,8), 2.1 (1.4‐3.0) and 3.0 (1.9‐4.7), respectively (P for trend < 0.01), and those for rectal adenoma were 1.0 (reference), 1.2 (0.4‐3.2), 3.5 (1.4‐8.5) and 2.0 (0.6‐6.7), respectively (P for trend = 0.03). Alcohol use was significantly positively associated with sigmoid adenoma, and insignificantly associated with rectal adenoma. Body mass index was significantly positively associated with sigmoid adenoma, especially large ones. No such association was found for rectal adenoma. These findings suggest that smoking, especially in the recent past, and alcohol use are common risk factors for sigmoid colon and rectal adenomas while obesity may be exclusively related to the growth of sigmoid adenoma. PMID:8567391

Perforated Sigmoid Diverticular Disease: a Management Protocol

PubMed Central

Moin, Thajammul

2008-01-01

Background: To develop an evidence-based protocol for the management of perforated sigmoid diverticular disease. Methods: A search of the literature was undertaken. All publications pertaining to perforated sigmoid diverticular disease were analyzed and then categorized according to their level of evidence. Recommendations were then made on the basis of this. Results: Multiple case reports suggest that primary closure of perforation of sigmoid diverticula is safe in the absence of peritoneal contamination. Conclusions: A 2-stage laparoscopic approach incorporating the principles of damage limitation surgery may be a safe strategy in the management of perforated diverticular disease. PMID:18435896

Adiabatic superconducting cells for ultra-low-power artificial neural networks.

PubMed

Schegolev, Andrey E; Klenov, Nikolay V; Soloviev, Igor I; Tereshonok, Maxim V

2016-01-01

We propose the concept of using superconducting quantum interferometers for the implementation of neural network algorithms with extremely low power dissipation. These adiabatic elements are Josephson cells with sigmoid- and Gaussian-like activation functions. We optimize their parameters for application in three-layer perceptron and radial basis function networks.

Nonlinear Growth Models in M"plus" and SAS

ERIC Educational Resources Information Center

Grimm, Kevin J.; Ram, Nilam

2009-01-01

Nonlinear growth curves or growth curves that follow a specified nonlinear function in time enable researchers to model complex developmental patterns with parameters that are easily interpretable. In this article we describe how a variety of sigmoid curves can be fit using the M"plus" structural modeling program and the nonlinear…

Comparison of all atom, continuum, and linear fitting empirical models for charge screening effect of aqueous medium surrounding a protein molecule

NASA Astrophysics Data System (ADS)

Takahashi, Takuya; Sugiura, Junnnosuke; Nagayama, Kuniaki

2002-05-01

To investigate the role hydration plays in the electrostatic interactions of proteins, the time-averaged electrostatic potential of the B1 domain of protein G in an aqueous solution was calculated with full atomic molecular dynamics simulations that explicitly considers every atom (i.e., an all atom model). This all atom calculated potential was compared with the potential obtained from an electrostatic continuum model calculation. In both cases, the charge-screening effect was fairly well formulated with an effective relative dielectric constant which increased linearly with increasing charge-charge distance. This simulated linear dependence agrees with the experimentally determined linear relation proposed by Pickersgill. Cut-off approximations for Coulomb interactions failed to reproduce this linear relation. Correlation between the all atom model and the continuum models was found to be better than the respective correlation calculated for linear fitting to the two models. This confirms that the continuum model is better at treating the complicated shapes of protein conformations than the simple linear fitting empirical model. We have tried a sigmoid fitting empirical model in addition to the linear one. When weights of all data were treated equally, the sigmoid model, which requires two fitting parameters, fits results of both the all atom and the continuum models less accurately than the linear model which requires only one fitting parameter. When potential values are chosen as weighting factors, the fitting error of the sigmoid model became smaller, and the slope of both linear fitting curves became smaller. This suggests the screening effect of an aqueous medium within a short range, where potential values are relatively large, is smaller than that expected from the linear fitting curve whose slope is almost 4. To investigate the linear increase of the effective relative dielectric constant, the Poisson equation of a low-dielectric sphere in a high-dielectric medium was solved and charges distributed near the molecular surface were indicated as leading to the apparent linearity.

Schwannoma of the sigmoid colon

PubMed Central

Çakır, Tuğrul; Aslaner, Arif; Yaz, Müjgan; Gündüz, Umut rıza

2015-01-01

Colonic schwannomas are very rare gastrointestinal tumours originating from Schwann cells, which form the neural sheath. Primary schwannomas of the lower gastrointestinal tract are very rare and usually benign in nature. However, if they are not surgically removed, malign degeneration can occur. We report a case of a 79-year-old woman who presented to our clinic with rectal bleeding and constipation. She underwent a lower gastrointestinal tract endoscopy. A mass subtotally obstructing the lumen of the sigmoid colon was seen and biopsies were taken. Histopathological examination indicated a suspicion of gastrointestinal tumour and the patient underwent sigmoid colon resection after preoperative evaluation by laboratory analysis, abdominal ultrasonography and CT. Her postoperative course was uneventful and she was discharged on the fifth day for outpatient control. The histopathology report revealed schwannoma of the sigmoid colon. This was a case of schwannoma of the sigmoid colon that was successfully treated with total resection. PMID:25976197

[A Case of Chemotherapy with FOLFOXIRI plus Cetuximab for Liver Metastasis of Sigmoid ColonCan cer].

PubMed

Saito, Akina; Konishi, Ken; Fukunaga, Mutsumi; Takiguchi, Nobuo; Nakai, Shigeto; Honda, Shoko; Yukimoto, Ryohei; Okamoto, Aoi; Takeoka, Tomohira; Matsuno, Hiroshi; Okada, Kazuyuki; Ota, Hideo; Yokoyama, Shigekazu; Konishi, Muneharu; Kobayashi, Kenji

2018-03-01

We report a case of chemotherapy with FOLFOXIRI plus cetuximab for liver metastasis of sigmoid colon cancer. The patient was a 40's man who was diagnosed with sigmoid colon cancer with liver metastasis. Colonoscopy revealed a type 2 tumor with stenosis in the sigmoid colon. He underwent sigmoidectomy under laparotomy, and after the operation, received 7 courses of chemotherapy with FOLFOXIRI plus cetuximab. The liver tumor was sufficiently reduced, and laparotomy and liver right lobectomy were performed. Histopathology revealed a modified, Grade 2 tumor regression. He has been followed for 1 year 4months after the operation.

Appropriate treatment of acute sigmoid volvulus in the emergency setting

PubMed Central

Lou, Zheng; Yu, En-Da; Zhang, Wei; Meng, Rong-Gui; Hao, Li-Qiang; Fu, Chuan-Gang

2013-01-01

AIM: To investigate an appropriate strategy for the treatment of patients with acute sigmoid volvulus in the emergency setting. METHODS: A retrospective review of 28 patients with acute sigmoid volvulus treated in the Department of Colorectal Surgery, Changhai Hospital, Shanghai from January 2001 to July 2012 was performed. Following the diagnosis of acute sigmoid volvulus, an initial colonoscopic approach was adopted if there was no evidence of diffuse peritonitis. RESULTS: Of the 28 patients with acute sigmoid volvulus, 19 (67.9%) were male and 9 (32.1%) were female. Their mean age was 63.1 ± 22.9 years (range, 21-93 years). Six (21.4%) patients had a history of abdominal surgery, and 17 (60.7%) patients had a history of constipation. Abdominal radiography or computed tomography was performed in all patients. Colonoscopic detorsion was performed in all 28 patients with a success rate of 92.8% (26/28). Emergency surgery was required in the other two patients. Of the 26 successfully treated patients, seven (26.9%) had recurrent volvulus. CONCLUSION: Colonoscopy is the primary emergency treatment of choice in uncomplicated acute sigmoid volvulus. Emergency surgery is only for patients in whom nonoperative treatment is unsuccessful, or in those with peritonitis. PMID:23946604

Sigmoid irrigation tube for the management of chronic evacuation disorders.

PubMed

Gauderer, Michael W L; Decou, James M; Boyle, John T

2002-03-01

Antegrade colonic irrigation, in which the right colon is accessed via appendicostomy or cecostomy, now is an important adjunct in the management of children with chronic evacuation disorders. However, in most children, the major area of dysfunction is the left rather than the right colon. The authors developed a simple, percutaneous endoscopic, laparoscopically controlled sigmoid irrigation tube placement and evaluated the results in 4 children. A rigid sigmoidoscope is advanced into the upper sigmoid and the loop brought in contact with the abdominal wall under laparoscopic control. A small skin incision is made and a needle pushed across the abdominal and sigmoid walls into the lumen of the sigmoidoscope. A guide wire is advanced through the needle into the scope and retrieved. After the scope is removed, a PEG-type catheter is attached to the guide wire and pulled back, securing the sigmoid loop to the abdominal wall. The tube is subsequently converted to a skin-level device by simply adding an external port valve. All 4 patients achieved prompt evacuation in the sitting position. Sigmoid tube for antegrade irrigation is an appealing alternative to conventional cecal access. The procedure is simple and may offer physiologic advantages. Copyright 2002 by W.B. Saunders Company.

Sigmoid CME Source Regions at the Sun: Some Recent Results

NASA Technical Reports Server (NTRS)

Sterling, Alphonse C.; Rose, M. Franklin (Technical Monitor)

2000-01-01

Identifying Coronal Mass Ejection (CME) precursors in the solar corona would be an important step in space weather forecasting, as well as a vital key to understanding the physics of CMEs. Twisted magnetic field structures are suspected of being the source of at least some CMEs. These features can appear sigmoid (S or inverse-S) shaped in soft X-ray (SXR) images. We review recent observations of these structures and their relation to CMEs, using soft X-ray (SXR) data from the Soft X-ray Telescope (SXT) on the Yohkoh satellite, and EUV data from the EUV Imaging Telescope (EIT) on the SOHO satellite. These observations indicate that the pre-eruption sigmoid patterns are more prominent in SXRs than in EUV, and that sigmoid precursors are present in over 50% of CMEs. These findings are important for CME research, and may potentially be a major component to space weather forecasting. So far, however, the studies have been subject to restrictions that will have to be relaxed before sigmoid morphology can be used as a reliable predictive tool. Moreover, some CMEs do not display a SXR sigmoid structure prior to eruption, and some others show no prominent SXR signature of any kind before or during eruption.

Sigmoid CME Source Regions at The Sun: Some Recent Results

NASA Technical Reports Server (NTRS)

Sterling, Alphonse C.

2000-01-01

Identifying coronal mass ejection (CME) precursors in the solar corona would be an important step in space weather forecasting, as well as a vital key to understanding the physics of CMEs. Twisted magnetic field structures are suspected of being the source of at least some CMEs. These features can appear sigmoid (S or inverse-S) shaped in soft X-ray, (SXR) images. We review recent observations of these structures and their relation to CMEs. using SXR data from the Soft X-ray Telescope (SXT) on the Yohkoh satellite, and EUV data from the EUV Imaging Telescope (EIT) on the SOHO satellite. These observations indicate that the pre-eruption sigmoid patterns are more prominent in SXRs than in EUV, and that sigmoid precursors are present in over 50% of CMEs. These findings are important for CME research, and may potentially be a major component to space weather forecasting. So far, however, the studies have been subject to restrictions that will have to be relaxed before sigmoid morphology can be used as a reliable predictive too[. Moreover, some CMEs do not display a SXR sigmoid structure prior to eruption, and some others show no prominent SXR signature of any kind before or during eruption.

Multidimensional density shaping by sigmoids.

PubMed

Roth, Z; Baram, Y

1996-01-01

An estimate of the probability density function of a random vector is obtained by maximizing the output entropy of a feedforward network of sigmoidal units with respect to the input weights. Classification problems can be solved by selecting the class associated with the maximal estimated density. Newton's optimization method, applied to the estimated density, yields a recursive estimator for a random variable or a random sequence. A constrained connectivity structure yields a linear estimator, which is particularly suitable for "real time" prediction. A Gaussian nonlinearity yields a closed-form solution for the network's parameters, which may also be used for initializing the optimization algorithm when other nonlinearities are employed. A triangular connectivity between the neurons and the input, which is naturally suggested by the statistical setting, reduces the number of parameters. Applications to classification and forecasting problems are demonstrated.

Individual tree-diameter growth model for the Northeastern United States

Treesearch

Richard M. Teck; Donald E. Hilt

1991-01-01

Describes a distance-independent individual-tree diameter growth model for the Northeastern United States. Diameter growth is predicted in two steps using a two parameter, sigmoidal growth function modified by a one parameter exponential decay function with species-specific coefficients. Coefficients are presented for 28 species groups. The model accounts for...

In vitro ovine articular chondrocyte proliferation: experiments and modelling.

PubMed

Mancuso, L; Liuzzo, M I; Fadda, S; Pisu, M; Cincotti, A; Arras, M; La Nasa, G; Concas, A; Cao, G

2010-06-01

This study focuses on analysis of in vitro cultures of chondrocytes from ovine articular cartilage. Isolated cells were seeded in Petri dishes, then expanded to confluence and phenotypically characterized by flow cytometry. The sigmoidal temporal profile of total counts was obtained by classic haemocytometry and corresponding cell size distributions were measured electronically using a Coulter Counter. A mathematical model recently proposed (1) was adopted for quantitative interpretation of these experimental data. The model is based on a 1-D (that is, mass-structured), single-staged population balance approach capable of taking into account contact inhibition at confluence. The model's parameters were determined by fitting measured total cell counts and size distributions. Model reliability was verified by predicting cell proliferation counts and corresponding size distributions at culture times longer than those used when tuning the model's parameters. It was found that adoption of cell mass as the intrinsic characteristic of a growing chondrocyte population enables sigmoidal temporal profiles of total counts in the Petri dish, as well as cell size distributions at 'balanced growth', to be adequately predicted.

Hydrothermal emergence model for ripgut brome (Bromus diandrus)

USDA-ARS?s Scientific Manuscript database

A model that describes the emergence of ripgut brome (Bromus diandrus) was developed using a two-season data set from a no-tilled field in northeastern Spain. The relationship between cumulative emergence and hydrothermal time (HTT) was described by a sigmoid growth function (Chapman equation). HTT ...

Discrimination of time-dependent inflow properties with a cooperative dynamical system.

PubMed

Ueno, Hiroshi; Tsuruyama, Tatsuaki; Nowakowski, Bogdan; Górecki, Jerzy; Yoshikawa, Kenichi

2015-10-01

Many physical, chemical, and biological systems exhibit a cooperative or sigmoidal response with respect to the input. In biochemistry, such behavior is called an allosteric effect. Here, we demonstrate that a system with such properties can be used to discriminate the amplitude or frequency of an external periodic perturbation. Numerical simulations performed for a model sigmoidal kinetics illustrate that there exists a narrow range of frequencies and amplitudes within which the system evolves toward significantly different states. Therefore, observation of system evolution should provide information about the characteristics of the perturbation. The discrimination properties for periodic perturbation are generic. They can be observed in various dynamical systems and for different types of periodic perturbation.

Ischemic or toxic injury: A challenging diagnosis and treatment of drug-induced stenosis of the sigmoid colon.

PubMed

Zhang, Zong-Ming; Lin, Xiang-Chun; Ma, Li; Jin, An-Qin; Lin, Fang-Cai; Liu, Zhuo; Liu, Li-Min; Zhang, Chong; Zhang, Na; Huo, Li-Juan; Jiang, Xue-Liang; Kang, Feng; Qin, Hong-Jun; Li, Qiu-Yang; Yu, Hong-Wei; Deng, Hai; Zhu, Ming-Wen; Liu, Zi-Xu; Wan, Bai-Jiang; Yang, Hai-Yan; Liao, Jia-Hong; Luo, Xu; Li, You-Wei; Wei, Wen-Ping; Song, Meng-Meng; Zhao, Yue; Shi, Xue-Ying; Lu, Zhao-Hui

2017-06-07

A 48-year-old woman was admitted with 15-mo history of abdominal pain, diarrhea and hematochezia, and 5-mo history of defecation difficulty. She had been successively admitted to nine hospitals, with an initial diagnosis of inflammatory bowel disease with stenotic sigmoid colon. Findings from computed tomography virtual colonoscopy, radiography with meglumine diatrizoate, endoscopic balloon dilatation, metallic stent implantation and later overall colonoscopy, coupled with the newfound knowledge of compound Qingdai pill-taking, led to a subsequent diagnosis of ischemic or toxic bowel disease with sigmoid colon stenosis. The patient was successfully treated by laparoscopic sigmoid colectomy, and postoperative pathological examination revealed ischemic or toxic injury of the sigmoid colon, providing a final diagnosis of drug-induced sigmoid colon stenosis. This case highlights that adequate awareness of drug-induced colon stenosis has a decisive role in avoiding misdiagnosis and mistreatment. The diagnostic and therapeutic experiences learnt from this case suggest that endoscopic balloon expansion and colonic metallic stent implantation as bridge treatments were demonstrated as crucial for the differential diagnosis of benign colonic stenosis. Skillful surgical technique and appropriate perioperative management helped to ensure the safety of our patient in subsequent surgery after long-term use of glucocorticoids.

Ischemic or toxic injury: A challenging diagnosis and treatment of drug-induced stenosis of the sigmoid colon

PubMed Central

Zhang, Zong-Ming; Lin, Xiang-Chun; Ma, Li; Jin, An-Qin; Lin, Fang-Cai; Liu, Zhuo; Liu, Li-Min; Zhang, Chong; Zhang, Na; Huo, Li-Juan; Jiang, Xue-Liang; Kang, Feng; Qin, Hong-Jun; Li, Qiu-Yang; Yu, Hong-Wei; Deng, Hai; Zhu, Ming-Wen; Liu, Zi-Xu; Wan, Bai-Jiang; Yang, Hai-Yan; Liao, Jia-Hong; Luo, Xu; Li, You-Wei; Wei, Wen-Ping; Song, Meng-Meng; Zhao, Yue; Shi, Xue-Ying; Lu, Zhao-Hui

2017-01-01

A 48-year-old woman was admitted with 15-mo history of abdominal pain, diarrhea and hematochezia, and 5-mo history of defecation difficulty. She had been successively admitted to nine hospitals, with an initial diagnosis of inflammatory bowel disease with stenotic sigmoid colon. Findings from computed tomography virtual colonoscopy, radiography with meglumine diatrizoate, endoscopic balloon dilatation, metallic stent implantation and later overall colonoscopy, coupled with the newfound knowledge of compound Qingdai pill-taking, led to a subsequent diagnosis of ischemic or toxic bowel disease with sigmoid colon stenosis. The patient was successfully treated by laparoscopic sigmoid colectomy, and postoperative pathological examination revealed ischemic or toxic injury of the sigmoid colon, providing a final diagnosis of drug-induced sigmoid colon stenosis. This case highlights that adequate awareness of drug-induced colon stenosis has a decisive role in avoiding misdiagnosis and mistreatment. The diagnostic and therapeutic experiences learnt from this case suggest that endoscopic balloon expansion and colonic metallic stent implantation as bridge treatments were demonstrated as crucial for the differential diagnosis of benign colonic stenosis. Skillful surgical technique and appropriate perioperative management helped to ensure the safety of our patient in subsequent surgery after long-term use of glucocorticoids. PMID:28638234

Impaction of swallowed dentures in the sigmoid colon requiring sigmoid colectomy.

PubMed

Flanagan, Michael; Clancy, Cillian; O Riordain, Micheal G

2018-05-07

Foreign body (FB) ingestion results in perforation in 1% of cases and is associated with significant morbidity and rarely mortality. Clinical presentation is variable and can present a diagnostic challenge. We report our experience and management of a patient with a delayed presentation of a sigmoid colon foreign body as a result of ingestion of a dental plate. A 67 year old female attended the colorectal outpatient clinic following an incidental finding of a sigmoid mass on computed tomography (CT) abdomen. Further investigation identified a dental plate impacted in a thickened sigmoid colon. On further questioning the patient recalled losing her dentures three years previously. At surgery the dental plate had partially eroded through the sigmoid colon into the pelvic side wall. A sigmoid colectomy and hand sewn end-to-end colo-colic anastomosis was performed. Localised perforation following ingestion of a foreign body may result in significant morbidity. Extra luminal migration and local inflammatory response resulted in the formation of a walled off collection. Delayed complications of perforation include abscess and fistula formation. Clinicians need to exhibit a high index of suspicion when treating edentulous patients and alcohol and drug abusers who present with an acute abdomen or a sub-acute presentation with associated atypical imaging and endoscopic findings. The decision regarding intervention and management strategy in cases of perforation by foreign body depends on chronicity of the case, extent of localised or diffuse peritonitis, and size of the lesion or area of bowel involved. Copyright © 2018. Published by Elsevier Ltd.

In vivo gliding and contact characteristics of the sigmoid notch and the ulna in forearm rotation.

PubMed

Chen, Yan Rong; Tang, Jin Bo

2013-08-01

To investigate shifting of the contact center over the surfaces of 2 opposing bones of the distal radioulnar joint during forearm rotation. We recruited 8 volunteers and used their right wrists. Serial computed tomography scans were obtained with the forearm at neutral position and 6 other positions of forearm rotation. We reconstructed 3-dimensional images and mapped contact regions of both the sigmoid notch and ulnar head by calculating the shortest distance between the 2 opposing bones. The center of contact was also defined and plotted against the distal radioulnar joint rotation to determine the sliding distance over the surfaces of the 2 bones. During forearm rotation, the maximal sliding of the sigmoid notch over the ulnar head was 7.4 mm in forearm pronation and 9.2 mm in forearm supination, which occurred in volar-dorsal direction primarily. Sliding of the ulnar head over the sigmoid notch was more limited, measuring 4.7 mm during pronation and 2.3 mm during supination. Most of the motion occurred between 30° pronation and 60° supination. In the proximal-distal direction, the contact site of the sigmoid notch with the ulnar head translated distally 1.6 mm during pronation and proximally 0.7 mm during supination. During forearm rotation, the sigmoid notch slides substantially against the ulnar head at each part of the forearm rotation arc. The sliding of the ulnar head over the sigmoid notch is smaller, most of which is at the range from moderate forearm pronation to slight supination. The contact site of the sigmoid notch with the ulnar head moves slightly distally during forearm pronation and proximally during supination. The in vivo findings provide more detailed information and insight into distal radioulnar joint motion kinematics. Copyright © 2013 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Mechanical analysis of non-uniform bi-directional functionally graded intelligent micro-beams using modified couple stress theory

NASA Astrophysics Data System (ADS)

Bakhshi Khaniki, Hossein; Rajasekaran, Sundaramoorthy

2018-05-01

This study develops a comprehensive investigation on mechanical behavior of non-uniform bi-directional functionally graded beam sensors in the framework of modified couple stress theory. Material variation is modelled through both length and thickness directions using power-law, sigmoid and exponential functions. Moreover, beam is assumed with linear, exponential and parabolic cross-section variation through the length using power-law and sigmoid varying functions. Using these assumptions, a general model for microbeams is presented and formulated by employing Hamilton’s principle. Governing equations are solved using a mixed finite element method with Lagrangian interpolation technique, Gaussian quadrature method and Wilson’s Lagrangian multiplier method. It is shown that by using bi-directional functionally graded materials in nonuniform microbeams, mechanical behavior of such structures could be affected noticeably and scale parameter has a significant effect in changing the rigidity of nonuniform bi-directional functionally graded beams.

Loss of competition in the outside host environment generates outbreaks of environmental opportunist pathogens.

PubMed

Anttila, Jani; Ruokolainen, Lasse; Kaitala, Veijo; Laakso, Jouni

2013-01-01

Environmentally transmitted pathogens face ecological interactions (e.g., competition, predation, parasitism) in the outside-host environment and host immune system during infection. Despite the ubiquitousness of environmental opportunist pathogens, traditional epidemiology focuses on obligatory pathogens incapable of environmental growth. Here we ask how competitive interactions in the outside-host environment affect the dynamics of an opportunist pathogen. We present a model coupling the classical SI and Lotka-Volterra competition models. In this model we compare a linear infectivity response and a sigmoidal infectivity response. An important assumption is that pathogen virulence is traded off with competitive ability in the environment. Removing this trade-off easily results in host extinction. The sigmoidal response is associated with catastrophic appearances of disease outbreaks when outside-host species richness, or overall competition pressure, decreases. This indicates that alleviating outside-host competition with antibacterial substances that also target the competitors can have unexpected outcomes by providing benefits for opportunist pathogens. These findings may help in developing alternative ways of controlling environmental opportunist pathogens.

Systems, methods and computer-readable media to model kinetic performance of rechargeable electrochemical devices

DOEpatents

Gering, Kevin L.

2013-01-01

A system includes an electrochemical cell, monitoring hardware, and a computing system. The monitoring hardware samples performance characteristics of the electrochemical cell. The computing system determines cell information from the performance characteristics. The computing system also analyzes the cell information of the electrochemical cell with a Butler-Volmer (BV) expression modified to determine exchange current density of the electrochemical cell by including kinetic performance information related to pulse-time dependence, electrode surface availability, or a combination thereof. A set of sigmoid-based expressions may be included with the modified-BV expression to determine kinetic performance as a function of pulse time. The determined exchange current density may be used with the modified-BV expression, with or without the sigmoid expressions, to analyze other characteristics of the electrochemical cell. Model parameters can be defined in terms of cell aging, making the overall kinetics model amenable to predictive estimates of cell kinetic performance along the aging timeline.

Use of selection indices to model the functional response of predators

USGS Publications Warehouse

Joly, D.O.; Patterson, B.R.

2003-01-01

The functional response of a predator to changing prey density is an important determinant of stability of predatora??prey systems. We show how Manly's selection indices can be used to distinguish between hyperbolic and sigmoidal models of a predator functional response to primary prey density in the presence of alternative prey. Specifically, an inverse relationship between prey density and preference for that prey results in a hyperbolic functional response while a positive relationship can yield either a hyperbolic or sigmoidal functional response, depending on the form and relative magnitudes of the density-dependent preference model, attack rate, and handling time. As an example, we examine wolf (Canis lupus) functional response to moose (Alces alces) density in the presence of caribou (Rangifer tarandus). The use of selection indices to evaluate the form of the functional response has significant advantages over previous attempts to fit Holling's functional response curves to killing-rate data directly, including increased sensitivity, use of relatively easily collected data, and consideration of other explanatory factors (e.g., weather, seasons, productivity).

[Destructive mastoiditis with thrombosis of the sigmoid sinus in a 8 year-old child presenting with concomitant chicken pox].

PubMed

Bogomil'skiĭ, M R; Polunin, M M; Ivanenko, A M; Poliakov, A A

2014-01-01

The specific clinical feature of mastoidities that developed in a patient presenting with chicken pox was the rapid progress in temporal bone destruction with partial thrombosis of the sigmoid sinusis in the absence of typical manifestations of mastoiditis. The pronounced destructive changes found in a series of CT images were regarded as the indications for urgent antromastoidotomy with the puncture of the sigmoid sinusis.

Virtual reality simulator training for laparoscopic colectomy: what metrics have construct validity?

PubMed

Shanmugan, Skandan; Leblanc, Fabien; Senagore, Anthony J; Ellis, C Neal; Stein, Sharon L; Khan, Sadaf; Delaney, Conor P; Champagne, Bradley J

2014-02-01

Virtual reality simulation for laparoscopic colectomy has been used for training of surgical residents and has been considered as a model for technical skills assessment of board-eligible colorectal surgeons. However, construct validity (the ability to distinguish between skill levels) must be confirmed before widespread implementation. This study was designed to specifically determine which metrics for laparoscopic sigmoid colectomy have evidence of construct validity. General surgeons that had performed fewer than 30 laparoscopic colon resections and laparoscopic colorectal experts (>200 laparoscopic colon resections) performed laparoscopic sigmoid colectomy on the LAP Mentor model. All participants received a 15-minute instructional warm-up and had never used the simulator before the study. Performance was then compared between each group for 21 metrics (procedural, 14; intraoperative errors, 7) to determine specifically which measurements demonstrate construct validity. Performance was compared with the Mann-Whitney U-test (p < 0.05 was significant). Fifty-three surgeons; 29 general surgeons, and 24 colorectal surgeons enrolled in the study. The virtual reality simulators for laparoscopic sigmoid colectomy demonstrated construct validity for 8 of 14 procedural metrics by distinguishing levels of surgical experience (p < 0.05). The most discriminatory procedural metrics (p < 0.01) favoring experts were reduced instrument path length, accuracy of the peritoneal/medial mobilization, and dissection of the inferior mesenteric artery. Intraoperative errors were not discriminatory for most metrics and favored general surgeons for colonic wall injury (general surgeons, 0.7; colorectal surgeons, 3.5; p = 0.045). Individual variability within the general surgeon and colorectal surgeon groups was not accounted for. The virtual reality simulators for laparoscopic sigmoid colectomy demonstrated construct validity for 8 procedure-specific metrics. However, using virtual reality simulator metrics to detect intraoperative errors did not discriminate between groups. If the virtual reality simulator continues to be used for the technical assessment of trainees and board-eligible surgeons, the evaluation of performance should be limited to procedural metrics.

Membership generation using multilayer neural network

NASA Technical Reports Server (NTRS)

Kim, Jaeseok

1992-01-01

There has been intensive research in neural network applications to pattern recognition problems. Particularly, the back-propagation network has attracted many researchers because of its outstanding performance in pattern recognition applications. In this section, we describe a new method to generate membership functions from training data using a multilayer neural network. The basic idea behind the approach is as follows. The output values of a sigmoid activation function of a neuron bear remarkable resemblance to membership values. Therefore, we can regard the sigmoid activation values as the membership values in fuzzy set theory. Thus, in order to generate class membership values, we first train a suitable multilayer network using a training algorithm such as the back-propagation algorithm. After the training procedure converges, the resulting network can be treated as a membership generation network, where the inputs are feature values and the outputs are membership values in the different classes. This method allows fairly complex membership functions to be generated because the network is highly nonlinear in general. Also, it is to be noted that the membership functions are generated from a classification point of view. For pattern recognition applications, this is highly desirable, although the membership values may not be indicative of the degree of typicality of a feature value in a particular class.

A deterministic model for highly contagious diseases: The case of varicella

NASA Astrophysics Data System (ADS)

Acedo, L.; Moraño, J.-A.; Santonja, F.-J.; Villanueva, R.-J.

2016-05-01

The classic nonlinear Kermack-McKendrick model based upon a system of differential equations has been widely applied to model the rise and fall of global pandemic and also seasonal epidemic by introducing a forced harmonic infectivity which would change throughout the year. These methods work well in their respective domains of applicability, and for certain diseases, but they fail when both seasonality and high infectivity are combined. In this paper we consider a Susceptible-Infected-Recovered, or SIR, model with two latent states to model the propagation and evolutionary history of varicella in humans. We show that infectivity can be calculated from real data and we find a nonstandard seasonal variation that cannot be fitted with a single harmonic. Moreover, we show that infectivity for the present strains of the virus has raised following a sigmoid function in a period of several centuries. This could allow the design of vaccination strategies and the study of the epidemiology of varicella and herpes zoster.

Effects of self-coupling and asymmetric output on metastable dynamical transient firing patterns in arrays of neurons with bidirectional inhibitory coupling.

PubMed

Horikawa, Yo

2016-04-01

Metastable dynamical transient patterns in arrays of bidirectionally coupled neurons with self-coupling and asymmetric output were studied. First, an array of asymmetric sigmoidal neurons with symmetric inhibitory bidirectional coupling and self-coupling was considered and the bifurcations of its steady solutions were shown. Metastable dynamical transient spatially nonuniform states existed in the presence of a pair of spatially symmetric stable solutions as well as unstable spatially nonuniform solutions in a restricted range of the output gain of a neuron. The duration of the transients increased exponentially with the number of neurons up to the maximum number at which the spatially nonuniform steady solutions were stabilized. The range of the output gain for which they existed reduced as asymmetry in a sigmoidal output function of a neuron increased, while the existence range expanded as the strength of inhibitory self-coupling increased. Next, arrays of spiking neuron models with slow synaptic inhibitory bidirectional coupling and self-coupling were considered with computer simulation. In an array of Class 1 Hindmarsh-Rose type models, in which each neuron showed a graded firing rate, metastable dynamical transient firing patterns were observed in the presence of inhibitory self-coupling. This agreed with the condition for the existence of metastable dynamical transients in an array of sigmoidal neurons. In an array of Class 2 Bonhoeffer-van der Pol models, in which each neuron had a clear threshold between firing and resting, long-lasting transient firing patterns with bursting and irregular motion were observed. Copyright © 2016 Elsevier Ltd. All rights reserved.

The cost effectiveness of elective laparoscopic sigmoid resection for symptomatic diverticular disease: financial outcome of the randomized control Sigma trial.

PubMed

Klarenbeek, Bastiaan R; Coupé, Veerle M H; van der Peet, Donald L; Cuesta, Miguel A

2011-03-01

Direct healthcare costs of patients with symptomatic diverticular disease randomized for either laparoscopic or open elective sigmoid resection are compared. Cost-effectiveness analysis of the laparoscopic approach compared with open sigmoid resections is presented. An economic evaluation of the randomized control Sigma trial was conducted, comparing elective laparoscopic sigmoid resection (LSR) to open sigmoid resection (OSR) in patients with symptomatic diverticulitis. Prospective registration of detailed intervention units per patient resulted in actual resource use per individual patient. To avoid distributional assumptions, the nonparametric bootstrap was applied. For the cost-effectiveness analysis, differences in total cost between LSR and OSR were compared with the differences in VAS pain score, SF-36 values for general health, and complication rate. The difference in total healthcare costs between the group that received LSR (euro 9969) and the group that received OSR (euro 9366) was not statistically significant. The slight increase in total costs was determined mainly by the significantly higher operation costs of LSR (euro 6663 vs. euro 5306). Lower costs for hospitalization (euro 2983 vs. euro 3598), blood products (euro 87 vs. euro 240), paramedical services (euro 157 vs. euro 278), and emergency attendance (euro 72 vs. euro 115) in the LSR group partially compensated these increased operation costs. The incremental cost-effectiveness ratios (ICER) indicate that improvements in pain, quality of life, and complication rate could be achieved at limited costs. Total healthcare costs of laparoscopic and open elective sigmoid resections for symptomatic diverticular disease are similar. As the clinical outcomes are in favor of the LSR group, candidates for an elective sigmoid resection should preferably be approached laparoscopically.

More patients should undergo surgery after sigmoid volvulus.

PubMed

Ifversen, Anne Kathrine Wewer; Kjaer, Daniel Willy

2014-12-28

To assess the outcome of patients treated conservatively vs surgically during their first admission for sigmoid volvulus. We conducted a retrospective study of 61 patients admitted to Aarhus University Hospital in Denmark between 1996 and 2011 for their first incidence of sigmoid volvulus. The condition was diagnosed by radiography, sigmoidoscopy or surgery. Patients treated with surgery underwent either a sigmoid resection or a percutaneous endoscopic colostomy (PEC). Conservatively treated patients were managed without surgery. Data was recorded into a Microsoft Access database and calculations were performed with Microsoft Excel. Kaplan-Meier plotting and Mantel-Cox (log-rank) testing were performed using GraphPad Prism software. Mortality was defined as death within 30 d after intervention or surgery. Among the total 61 patients, 4 underwent emergency surgery, 55 underwent endoscopy, 1 experienced resolution of the volvulus after contrast enema, and 1 died without treatment because of large bowel perforation. Following emergency treatment, 28 patients underwent sigmoid resection (semi-elective n = 18; elective n = 10). Two patients who were unfit for surgery underwent PEC and both died, 1 after 36 d and the other after 9 mo, respectively. The remaining 26 patients were managed conservatively without sigmoid resection. Patients treated conservatively on their first admission had a poorer survival rate than patients treated surgically on their first admission (95%CI: 3.67-14.37, P = 0.036). Sixty-three percent of the 26 conservatively treated patients had not experienced a recurrence 3 mo after treatment, but that number dropped to 24% 2 years after treatment. Eight of the 14 patients with recurrence after conservative treatment had surgery with no 30-d mortality. Surgically-treated sigmoid volvulus patients had a higher long-term survival rate than conservatively managed patients, indicating a benefit of surgical resection or PEC insertion if feasible.

More patients should undergo surgery after sigmoid volvulus

PubMed Central

Ifversen, Anne Kathrine Wewer; Kjaer, Daniel Willy

2014-01-01

AIM: To assess the outcome of patients treated conservatively vs surgically during their first admission for sigmoid volvulus. METHODS: We conducted a retrospective study of 61 patients admitted to Aarhus University Hospital in Denmark between 1996 and 2011 for their first incidence of sigmoid volvulus. The condition was diagnosed by radiography, sigmoidoscopy or surgery. Patients treated with surgery underwent either a sigmoid resection or a percutaneous endoscopic colostomy (PEC). Conservatively treated patients were managed without surgery. Data was recorded into a Microsoft Access database and calculations were performed with Microsoft Excel. Kaplan-Meier plotting and Mantel-Cox (log-rank) testing were performed using GraphPad Prism software. Mortality was defined as death within 30 d after intervention or surgery. RESULTS: Among the total 61 patients, 4 underwent emergency surgery, 55 underwent endoscopy, 1 experienced resolution of the volvulus after contrast enema, and 1 died without treatment because of large bowel perforation. Following emergency treatment, 28 patients underwent sigmoid resection (semi-elective n = 18; elective n = 10). Two patients who were unfit for surgery underwent PEC and both died, 1 after 36 d and the other after 9 mo, respectively. The remaining 26 patients were managed conservatively without sigmoid resection. Patients treated conservatively on their first admission had a poorer survival rate than patients treated surgically on their first admission (95%CI: 3.67-14.37, P = 0.036). Sixty-three percent of the 26 conservatively treated patients had not experienced a recurrence 3 mo after treatment, but that number dropped to 24% 2 years after treatment. Eight of the 14 patients with recurrence after conservative treatment had surgery with no 30-d mortality. CONCLUSION: Surgically-treated sigmoid volvulus patients had a higher long-term survival rate than conservatively managed patients, indicating a benefit of surgical resection or PEC insertion if feasible. PMID:25561806

Resection and primary anastomosis with or without modified blow-hole colostomy for sigmoid volvulus

PubMed Central

Coban, Sacid; Yilmaz, Mehmet; Terzi, Alpaslan; Yildiz, Fahrettin; Ozgor, Dincer; Ara, Cengiz; Yologlu, Saim; Kirimlioglu, Vedat

2008-01-01

AIM: To evaluate the efficacy of resection and primary anastomosis (RPA) and RPA with modified blow-hole colostomy for sigmoid volvulus. METHODS: From March 2000 to September 2007, 77 patients with acute sigmoid volvulus were treated. A total of 47 patients underwent RPA or RPA with modified blow-hole colostomy. Twenty-five patients received RPA (Group A), and the remaining 22 patients had RPA with modified blow-hole colostomy (Group B). The clinical course and postoperative complications of the two groups were compared. RESULTS: The mean hospital stay, wound infection and mortality did not differ significantly between the groups. Superficial wound infection rate was higher in group A (32% vs 9.1%). Anastomotic leakage was observed only in group A, with a rate of 6.3%. The difference was numerically impressive but was statistically not significant. CONCLUSION: RPA with modified blow-hole colostomy provides satisfactory results. It is easy to perform and may become a method of choice in patients with sigmoid volvulus. Further studies are required to further establish its role in the treatment of sigmoid volvulus. PMID:18810779

Neoplastic sigmoid-uterine fistula. An exceptional complication of large intestine cancer

PubMed Central

ZANGHÌ, G.; LEANZA, V.; VECCHIO, R.; D’AGATI, A.; CORDOVA, S.; RINZIVILLO, N.M.; LODATO, M.; LEANZA, G.

2017-01-01

Neoplastic sigmoid-uterine fistula is an extremely rare condition because the uterus is a thick and muscular organ. A 74-year-old woman was admitted to the First Aid Station suffering from abdominal pain and foul smelling vaginal discharge. Gynaecological examination showed fecal drainage from the cervical orifice, while the uterus was regular in size but very firm and painful. Ovaries and fallopian tubes were not palpable owing to abdominal tenderness. Ultrasounds reveled inhomogeneous thickening of uterine cavity, without detecting fistula. Contrast Medium CT (CMCT) showed Douglas’ recto-uterine pouch occluded. The sigmoid wall was very thin exception a site where a fistula was suspected. At the surgery severe adhesions of the sigma-rectum with the posterior uterine wall were observed. After adhesiolysis, 18 cm colon-sigma-rectum was removed. Total hysterectomy with salpingooophorectomy was performed. Lymphadenectomy ended the procedure. Anatomical specimen confirmed sigmoid-uterine fistula. At histology a mildly differentiated adenocarcinoma of sigma-rectum was shown. Postoperative course was uneventful. Such a case of neoplastic sigmoid-uterine fistula has not been reported so far. PMID:28460202

Variational dynamic background model for keyword spotting in handwritten documents

NASA Astrophysics Data System (ADS)

Kumar, Gaurav; Wshah, Safwan; Govindaraju, Venu

2013-12-01

We propose a bayesian framework for keyword spotting in handwritten documents. This work is an extension to our previous work where we proposed dynamic background model, DBM for keyword spotting that takes into account the local character level scores and global word level scores to learn a logistic regression classifier to separate keywords from non-keywords. In this work, we add a bayesian layer on top of the DBM called the variational dynamic background model, VDBM. The logistic regression classifier uses the sigmoid function to separate keywords from non-keywords. The sigmoid function being neither convex nor concave, exact inference of VDBM becomes intractable. An expectation maximization step is proposed to do approximate inference. The advantage of VDBM over the DBM is multi-fold. Firstly, being bayesian, it prevents over-fitting of data. Secondly, it provides better modeling of data and an improved prediction of unseen data. VDBM is evaluated on the IAM dataset and the results prove that it outperforms our prior work and other state of the art line based word spotting system.

Comparing basal area growth models, consistency of parameters, and accuracy of prediction

Treesearch

J.J. Colbert; Michael Schuckers; Desta Fekedulegn

2002-01-01

We fit alternative sigmoid growth models to sample tree basal area historical data derived from increment cores and disks taken at breast height. We examine and compare the estimated parameters for these models across a range of sample sites. Models are rated on consistency of parameters and on their ability to fit growth data from four sites that are located across a...

An open Markov chain scheme model for a credit consumption portfolio fed by ARIMA and SARMA processes

NASA Astrophysics Data System (ADS)

Esquível, Manuel L.; Fernandes, José Moniz; Guerreiro, Gracinda R.

2016-06-01

We introduce a schematic formalism for the time evolution of a random population entering some set of classes and such that each member of the population evolves among these classes according to a scheme based on a Markov chain model. We consider that the flow of incoming members is modeled by a time series and we detail the time series structure of the elements in each of the classes. We present a practical application to data from a credit portfolio of a Cape Verdian bank; after modeling the entering population in two different ways - namely as an ARIMA process and as a deterministic sigmoid type trend plus a SARMA process for the residues - we simulate the behavior of the population and compare the results. We get that the second method is more accurate in describing the behavior of the populations when compared to the observed values in a direct simulation of the Markov chain.

Sigmoid-vaginal fistula during bevacizumab treatment diagnosed by fistulography.

PubMed

Hayashi, C; Takada, S; Kasuga, A; Shinya, K; Watanabe, M; Kano, H; Takayama, T

2016-12-01

There have been several reports describing rectovaginal fistula development after bevacizumab treatment, and these fistulas were diagnosed by CT scan or colonoscopy. We report a case of sigmoid-vaginal fistula diagnosed by fistulography. The case is a 53-year-old woman who was treated for chronic myelogenous leukaemia and gynaecological cancers 8 years previously. At 52 years of age, she was diagnosed with colon cancer and had a partial colectomy performed. One year after surgery, colon cancer recurred, and she was treated with anticancer agents, including bevacizumab. During chemotherapy, she complained of a foul smelling discharge from the vagina. Fistulography revealed a sigmoid-vaginal fistula. This is the first report of vaginal fistulography performed on a patient who was treated with bevacizumab. Fistulography may be useful for detecting sigmoid-vaginal fistula. © 2016 John Wiley & Sons Ltd.

A case report and literature review of sigmoid volvulus in children.

PubMed

Chang, Po-Hsiung; Jeng, Chin-Ming; Chen, Der-Fang; Lin, Lung-Huang

2017-12-01

Sigmoid volvulus (SV) is an exceptionally rare but potentially life-threatening condition in children. Abdominal distention for 1 week. Sigmoid volvulus. We present a case of a 12-year-old boy with mechanical ileus who was finally confirmed to have SV with the combination of abdominal plain film, sonography, and computed tomography (CT) with the finding of mesenteric artery rotation. Because bowel obstruction was suspected, abdominal plain film, sonography, and CT were performed. The abdominal CT demonstrated whirlpool sign with torsion of the sigmoid vessels. In addition, lower gastrointestinal filling study showed that the contrast medium could only reach the upper descending colon. Therefore, he received laparotomy with mesosigmoidoplasty for detorsion of the sigmoid. The postoperative recovery was smooth under empirical antibiotic treatment with cefazolin. A follow-up lower gastrointestinal series on the seventh day of admission showed no obstruction compared with the previous series. He was finally discharged in a stable condition 8 days after admission. SV is a congenital anomaly and an uncommon diagnosis in children. Nevertheless, case series and case reports of SV are becoming more prevalent in the literature. Failure to recognize SV may result in life-threatening complications such as sigmoid gangrene/perforation, peritonitis, sepsis, and death. Thus, if the children have persistent and recurrent abdominal distention, abdominal pain, and vomiting, physicians should consider SV as a "do not miss diagnosis" in the differential diagnosis. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.

Characteristics of Modic changes in cervical kyphosis and their association with axial neck pain.

PubMed

An, Yonghui; Li, Jia; Li, Yongqian; Shen, Yong

2017-01-01

The purpose of this study was to evaluate characteristics of Modic changes in cervical kyphosis (CK) and their association with axial neck pain. Study participants included 286 asymptomatic or symptomatic patients with CK (mean age = 54.2 ± 12.2 years) who were consecutively enrolled from March 2009 to October 2015. Clinical and radiographic evaluations were performed at a university outpatient department. CK was classified as global type, reverse sigmoid type, or sigmoid type. There were 138 participants with global type CK, 103 with reverse sigmoid type CK, and 45 with sigmoid type CK. Of the 286 participants, 102 had Modic changes (Modic-1 in 38 segments and Modic-2 in 75 segments). Spinal cord compression grade and disc degeneration occurred more frequently in the group with axial neck pain compared to the group without pain. Angular motion was decreased in those with axial neck pain (mean ± standard deviation [SD] 7.8°±4.6°) compared to those who were asymptomatic (mean ± SD 8.9°±5.1°; P <0.001). In multivariate logistic regression analysis, Modic changes were associated with axial neck pain (odds ratio =5.356; 95% confidence interval =1.314-12.800; P <0.001). Modic changes occur most commonly in association with CK global type and less commonly with reverse sigmoid type and sigmoid type. Modic changes are associated with axial neck pain in patients with CK.

Modelling of Asphalt Concrete Stiffness in the Linear Viscoelastic Region

NASA Astrophysics Data System (ADS)

Mazurek, Grzegorz; Iwański, Marek

2017-10-01

Stiffness modulus is a fundamental parameter used in the modelling of the viscoelastic behaviour of bituminous mixtures. On the basis of the master curve in the linear viscoelasticity range, the mechanical properties of asphalt concrete at different loading times and temperatures can be predicted. This paper discusses the construction of master curves under rheological mathematical models i.e. the sigmoidal function model (MEPDG), the fractional model, and Bahia and co-workers’ model in comparison to the results from mechanistic rheological models i.e. the generalized Huet-Sayegh model, the generalized Maxwell model and the Burgers model. For the purposes of this analysis, the reference asphalt concrete mix (denoted as AC16W) intended for the binder coarse layer and for traffic category KR3 (5×105

AltitudeOmics: Resetting of Cerebrovascular CO2 Reactivity Following Acclimatization to High Altitude

PubMed Central

Fan, Jui-Lin; Subudhi, Andrew W.; Duffin, James; Lovering, Andrew T.; Roach, Robert C.; Kayser, Bengt

2016-01-01

Previous studies reported enhanced cerebrovascular CO2 reactivity upon ascent to high altitude using linear models. However, there is evidence that this response may be sigmoidal in nature. Moreover, it was speculated that these changes at high altitude are mediated by alterations in acid-base buffering. Accordingly, we reanalyzed previously published data to assess middle cerebral blood flow velocity (MCAv) responses to modified rebreathing at sea level (SL), upon ascent (ALT1) and following 16 days of acclimatization (ALT16) to 5260 m in 21 lowlanders. Using sigmoid curve fitting of the MCAv responses to CO2, we found the amplitude (95 vs. 129%, SL vs. ALT1, 95% confidence intervals (CI) [77, 112], [111, 145], respectively, P = 0.024) and the slope of the sigmoid response (4.5 vs. 7.5%/mmHg, SL vs. ALT1, 95% CIs [3.1, 5.9], [6.0, 9.0], respectively, P = 0.026) to be enhanced at ALT1, which persisted with acclimatization at ALT16 (amplitude: 177, 95% CI [139, 215], P < 0.001; slope: 10.3%/mmHg, 95% CI [8.2, 12.5], P = 0.003) compared to SL. Meanwhile, the sigmoidal response midpoint was unchanged at ALT1 (SL: 36.5 mmHg; ALT1: 35.4 mmHg, 95% CIs [34.0, 39.0], [33.1, 37.7], respectively, P = 0.982), while it was reduced by ~7 mmHg at ALT16 (28.6 mmHg, 95% CI [26.4, 30.8], P = 0.001 vs. SL), indicating leftward shift of the cerebrovascular CO2 response to a lower arterial partial pressure of CO2 (PaCO2) following acclimatization to altitude. Sigmoid fitting revealed a leftward shift in the midpoint of the cerebrovascular response curve which could not be observed with linear fitting. These findings demonstrate that there is resetting of the cerebrovascular CO2 reactivity operating point to a lower PaCO2 following acclimatization to high altitude. This cerebrovascular resetting is likely the result of an altered acid-base buffer status resulting from prolonged exposure to the severe hypocapnia associated with ventilatory acclimatization to high altitude. PMID:26779030

Predicting electroporation of cells in an inhomogeneous electric field based on mathematical modeling and experimental CHO-cell permeabilization to propidium iodide determination.

PubMed

Dermol, Janja; Miklavčič, Damijan

2014-12-01

High voltage electric pulses cause electroporation of the cell membrane. Consequently, flow of the molecules across the membrane increases. In our study we investigated possibility to predict the percentage of the electroporated cells in an inhomogeneous electric field on the basis of the experimental results obtained when cells were exposed to a homogeneous electric field. We compared and evaluated different mathematical models previously suggested by other authors for interpolation of the results (symmetric sigmoid, asymmetric sigmoid, hyperbolic tangent and Gompertz curve). We investigated the density of the cells and observed that it has the most significant effect on the electroporation of the cells while all four of the mathematical models yielded similar results. We were able to predict electroporation of cells exposed to an inhomogeneous electric field based on mathematical modeling and using mathematical formulations of electroporation probability obtained experimentally using exposure to the homogeneous field of the same density of cells. Models describing cell electroporation probability can be useful for development and presentation of treatment planning for electrochemotherapy and non-thermal irreversible electroporation. Copyright © 2014 Elsevier B.V. All rights reserved.

Cotton growth modeling and assessment using unmanned aircraft system visual-band imagery

NASA Astrophysics Data System (ADS)

Chu, Tianxing; Chen, Ruizhi; Landivar, Juan A.; Maeda, Murilo M.; Yang, Chenghai; Starek, Michael J.

2016-07-01

This paper explores the potential of using unmanned aircraft system (UAS)-based visible-band images to assess cotton growth. By applying the structure-from-motion algorithm, the cotton plant height (ph) and canopy cover (cc) information were retrieved from the point cloud-based digital surface models (DSMs) and orthomosaic images. Both UAS-based ph and cc follow a sigmoid growth pattern as confirmed by ground-based studies. By applying an empirical model that converts the cotton ph to cc, the estimated cc shows strong correlation (R2=0.990) with the observed cc. An attempt for modeling cotton yield was carried out using the ph and cc information obtained on June 26, 2015, the date when sigmoid growth curves for both ph and cc tended to decline in slope. In a cross-validation test, the correlation between the ground-measured yield and the estimated equivalent derived from the ph and/or cc was compared. Generally, combining ph and cc, the performance of the yield estimation is most comparable against the observed yield. On the other hand, the observed yield and cc-based estimation produce the second strongest correlation, regardless of the complexity of the models.

Neonatal sigmoid volvulus.

PubMed

Khalayleh, Harbi; Koplewitz, Benjamin Z; Kapuller, Vadim; Armon, Yaron; Abu-Leil, Sinan; Arbell, Dan

2016-11-01

Neonatal sigmoid volvulus is a rare entity. It is associated with Hirschsprung's disease. Presentation is acute abdominal distention, vomiting and obstipation. Abdominal radiograph will show the "coffee bean" sign, but this is frequently missed and the diagnosis requires a high index of suspicion. Treatment options include contrast enema, colonoscopy or laparotomy, depending on the condition of the baby and local availability. During the last 6years, 6 infants with sigmoid volvulus were treated in our department. Four presented during the first 48h since birth, and 2 presented at the age of 2 and 7weeks of age. One child was operated and 5 had primary contrast enema with radiologic de-volvulus. Rectal biopsy was performed in all cases; three children had Hirschsprung's disease. Those with normal biopsies responded well to rectal washouts. Two patients had early one stage transanal pullthrough and one had 2 further occasions of sigmoid volvulus prior to definitive surgery. All three recovered with an uneventful course. Neonatal sigmoid volvulus requires a high level of suspicion. Contrast enema is efficient for primary de-volvulus. Rectal biopsy should be performed and if positive for Hirschsprung's disease, surgery should be performed sooner rather than later. Copyright © 2016 Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chesny, D. L.; Oluseyi, H. M.; Orange, N. B.

Ubiquitous solar atmospheric coronal and transition region bright points (BPs) are compact features overlying strong concentrations of magnetic flux. Here, we utilize high-cadence observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to provide the first observations of extreme ultraviolet quiet-Sun (QS) network BP activity associated with sigmoidal structuring. To our knowledge, this previously unresolved fine structure has never been associated with such small-scale QS events. This QS event precedes a bi-directional jet in a compact, low-energy, and low-temperature environment, where evidence is found in support of the typical fan-spine magnetic field topology. As in active regionsmore » and micro-sigmoids, the sigmoidal arcade is likely formed via tether-cutting reconnection and precedes peak intensity enhancements and eruptive activity. Our QS BP sigmoid provides a new class of small-scale structuring exhibiting self-organized criticality that highlights a multi-scaled self-similarity between large-scale, high-temperature coronal fields and the small-scale, lower-temperature QS network. Finally, our QS BP sigmoid elevates arguments for coronal heating contributions from cooler atmospheric layers, as this class of structure may provide evidence favoring mass, energy, and helicity injections into the heliosphere.« less

Current modeling practice may lead to falsely high benchmark dose estimates.

PubMed

Ringblom, Joakim; Johanson, Gunnar; Öberg, Mattias

2014-07-01

Benchmark dose (BMD) modeling is increasingly used as the preferred approach to define the point-of-departure for health risk assessment of chemicals. As data are inherently variable, there is always a risk to select a model that defines a lower confidence bound of the BMD (BMDL) that, contrary to expected, exceeds the true BMD. The aim of this study was to investigate how often and under what circumstances such anomalies occur under current modeling practice. Continuous data were generated from a realistic dose-effect curve by Monte Carlo simulations using four dose groups and a set of five different dose placement scenarios, group sizes between 5 and 50 animals and coefficients of variations of 5-15%. The BMD calculations were conducted using nested exponential models, as most BMD software use nested approaches. "Non-protective" BMDLs (higher than true BMD) were frequently observed, in some scenarios reaching 80%. The phenomenon was mainly related to the selection of the non-sigmoidal exponential model (Effect=a·e(b)(·dose)). In conclusion, non-sigmoid models should be used with caution as it may underestimate the risk, illustrating that awareness of the model selection process and sound identification of the point-of-departure is vital for health risk assessment. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Individual tree basal-area growth parameter estimates for four models

Treesearch

J.J. Colbert; Michael Schuckers; Desta Fekedulegn; James Rentch; Mairtin MacSiurtain; Kurt Gottschalk

2004-01-01

Four sigmoid growth models are fit to basal-area data derived from increment cores and disks taken at breast height from oak trees. Models are rated on their ability to fit growth data from five datasets that are obtained from 10 locations along a longitudinal gradient across the states of Delaware, Pennsylvania, West Virginia, and Ohio in the USA. We examine and...

Inflammatory fibroid polyp of sigmoid colon.

PubMed

Lifschitz, O; Lew, S; Witz, M; Reiss, R; Griffel, B

1979-01-01

A case of inflammatory fibroid polyp of the sigmoid colon is presented. This is the eight case of this type of polyp in the colon and, to the best of our knowledge, the first one involving the sigmoid and producing intussusception. Symptomatology of the inflamed fibroid polyp in this part of the gut closely simulates gastrointestinal malignancy. The treatment is surgical excision of the polyp, or colonoscopic resection when it is possible. Intraoperative colonoscopy helps the surgeon to localize the lesion and to role out the existence of other lesions.

Invading of intrauterine contraceptive device into the sigmoid colon through uterine perforation caused by a blunt trauma.

PubMed

Davoodabadi, Abdoulhossein; Mohammadzadeh, Mahdi; Amirbeigi, Mahdieh; Jazayeri, Hoda

2015-01-01

Intrauterine contraceptive device (IUCD) is relatively safe but still with some serious risks. Uterus perforation is rare and would be fatal. A case of Cu-7 IUCD invading into the sigmoid colon through uterine perforation caused by a pelvic blunt trauma was presented. Our case showed that uterus perforation by an IUCD could induce utero-sigmoid fistula which is likely to be missed. Imaging is required when the patients with IUCD present abdominal pain, particularly with a history of trauma.

Giant Sigmoid Diverticulum: A Rare Presentation of a Common Pathology

PubMed Central

Guarnieri, A.; Cesaretti, M.; Tirone, A.; Francioli, N.; Piccolomini, A.; Vuolo, G.; Verre, L.; Savelli, V.; Di Cosmo, L.; Carli, A.F.

2009-01-01

Although colonic diverticulum is a common disease, affecting about 35% of patients above the age of 60, giant sigmoid diverticulum is an uncommon variant of which only relatively few cases have been described in the literature. We report on our experience with a patient affected by giant sigmoid diverticulum who was treated with diverticulectomy. Resection of the diverticulum is a safe surgical procedure, provided that the colon section close to the lesion presents no sign of flogosis or diverticula; in addition, recurrences are not reported after 6-year follow-up. PMID:20651957

Colonic motility in proctalgia fugax.

PubMed

Harvey, R F

1979-10-06

Intraluminal pressure recordings were obtained from the rectum and sigmoid colon in two patients experiencing attacks of proctalgia fugax. In each patient the pain appeared to result from contractions of the sigmoid colon, and not from spasm of the levator ani, rectal wall muscle, or anal sphincters, all of which have previously been suggested as the source of such pain. Proctalgia fugax therefore appears, at least in some patients, to be an unusual variant of the irritable bowel syndrome, in which pain is referred from the sigmoid colon to the rectum.

Supporting Solar Physics Research via Data Mining

NASA Astrophysics Data System (ADS)

Angryk, Rafal; Banda, J.; Schuh, M.; Ganesan Pillai, K.; Tosun, H.; Martens, P.

2012-05-01

In this talk we will briefly introduce three pillars of data mining (i.e. frequent patterns discovery, classification, and clustering), and discuss some possible applications of known data mining techniques which can directly benefit solar physics research. In particular, we plan to demonstrate applicability of frequent patterns discovery methods for the verification of hypotheses about co-occurrence (in space and time) of filaments and sigmoids. We will also show how classification/machine learning algorithms can be utilized to verify human-created software modules to discover individual types of solar phenomena. Finally, we will discuss applicability of clustering techniques to image data processing.

Gabor-based kernel PCA with fractional power polynomial models for face recognition.

PubMed

Liu, Chengjun

2004-05-01

This paper presents a novel Gabor-based kernel Principal Component Analysis (PCA) method by integrating the Gabor wavelet representation of face images and the kernel PCA method for face recognition. Gabor wavelets first derive desirable facial features characterized by spatial frequency, spatial locality, and orientation selectivity to cope with the variations due to illumination and facial expression changes. The kernel PCA method is then extended to include fractional power polynomial models for enhanced face recognition performance. A fractional power polynomial, however, does not necessarily define a kernel function, as it might not define a positive semidefinite Gram matrix. Note that the sigmoid kernels, one of the three classes of widely used kernel functions (polynomial kernels, Gaussian kernels, and sigmoid kernels), do not actually define a positive semidefinite Gram matrix either. Nevertheless, the sigmoid kernels have been successfully used in practice, such as in building support vector machines. In order to derive real kernel PCA features, we apply only those kernel PCA eigenvectors that are associated with positive eigenvalues. The feasibility of the Gabor-based kernel PCA method with fractional power polynomial models has been successfully tested on both frontal and pose-angled face recognition, using two data sets from the FERET database and the CMU PIE database, respectively. The FERET data set contains 600 frontal face images of 200 subjects, while the PIE data set consists of 680 images across five poses (left and right profiles, left and right half profiles, and frontal view) with two different facial expressions (neutral and smiling) of 68 subjects. The effectiveness of the Gabor-based kernel PCA method with fractional power polynomial models is shown in terms of both absolute performance indices and comparative performance against the PCA method, the kernel PCA method with polynomial kernels, the kernel PCA method with fractional power polynomial models, the Gabor wavelet-based PCA method, and the Gabor wavelet-based kernel PCA method with polynomial kernels.

Smoothing tautologies, hidden dynamics, and sigmoid asymptotics for piecewise smooth systems

NASA Astrophysics Data System (ADS)

Jeffrey, Mike R.

2015-10-01

Switches in real systems take many forms, such as impacts, electronic relays, mitosis, and the implementation of decisions or control strategies. To understand what is lost, and what can be retained, when we model a switch as an instantaneous event, requires a consideration of so-called hidden terms. These are asymptotically vanishing outside the switch, but can be encoded in the form of nonlinear switching terms. A general expression for the switch can be developed in the form of a series of sigmoid functions. We review the key steps in extending Filippov's method of sliding modes to such systems. We show how even slight nonlinear effects can hugely alter the behaviour of an electronic control circuit, and lead to "hidden" attractors inside the switching surface.

Smoothing tautologies, hidden dynamics, and sigmoid asymptotics for piecewise smooth systems.

PubMed

Jeffrey, Mike R

2015-10-01

Switches in real systems take many forms, such as impacts, electronic relays, mitosis, and the implementation of decisions or control strategies. To understand what is lost, and what can be retained, when we model a switch as an instantaneous event, requires a consideration of so-called hidden terms. These are asymptotically vanishing outside the switch, but can be encoded in the form of nonlinear switching terms. A general expression for the switch can be developed in the form of a series of sigmoid functions. We review the key steps in extending Filippov's method of sliding modes to such systems. We show how even slight nonlinear effects can hugely alter the behaviour of an electronic control circuit, and lead to "hidden" attractors inside the switching surface.

Smoothing tautologies, hidden dynamics, and sigmoid asymptotics for piecewise smooth systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeffrey, Mike R., E-mail: mike.jeffrey@bristol.ac.uk

2015-10-15

Switches in real systems take many forms, such as impacts, electronic relays, mitosis, and the implementation of decisions or control strategies. To understand what is lost, and what can be retained, when we model a switch as an instantaneous event, requires a consideration of so-called hidden terms. These are asymptotically vanishing outside the switch, but can be encoded in the form of nonlinear switching terms. A general expression for the switch can be developed in the form of a series of sigmoid functions. We review the key steps in extending Filippov's method of sliding modes to such systems. We showmore » how even slight nonlinear effects can hugely alter the behaviour of an electronic control circuit, and lead to “hidden” attractors inside the switching surface.« less

The "Sigmoid Sniffer” and the "Advanced Automated Solar Filament Detection and Characterization Code” Modules

NASA Astrophysics Data System (ADS)

Raouafi, Noureddine; Bernasconi, P. N.; Georgoulis, M. K.

2010-05-01

We present two pattern recognition algorithms, the "Sigmoid Sniffer” and the "Advanced Automated Solar Filament Detection and Characterization Code,” that are among the Feature Finding modules of the Solar Dynamic Observatory: 1) Coronal sigmoids visible in X-rays and the EUV are the result of highly twisted magnetic fields. They can occur anywhere on the solar disk and are closely related to solar eruptive activity (e.g., flares, CMEs). Their appearance is typically synonym of imminent solar eruptions, so they can serve as a tool to forecast solar activity. Automatic X-ray sigmoid identification offers an unbiased way of detecting short-to-mid term CME precursors. The "Sigmoid Sniffer” module is capable of automatically detecting sigmoids in full-disk X-ray images and determining their chirality, as well as other characteristics. It uses multiple thresholds to identify persistent bright structures on a full-disk X-ray image of the Sun. We plan to apply the code to X-ray images from Hinode/XRT, as well as on SDO/AIA images. When implemented in a near real-time environment, the Sigmoid Sniffer could allow 3-7 day forecasts of CMEs and their potential to cause major geomagnetic storms. 2)The "Advanced Automated Solar Filament Detection and Characterization Code” aims to identify, classify, and track solar filaments in full-disk Hα images. The code can reliably identify filaments; determine their chirality and other relevant parameters like filament area, length, and average orientation with respect to the equator. It is also capable of tracking the day-by-day evolution of filaments as they traverse the visible disk. The code was tested by analyzing daily Hα images taken at the Big Bear Solar Observatory from mid-2000 to early-2005. It identified and established the chirality of thousands of filaments without human intervention.

[Comparative study on laparoscopic vaginoplasty using pedicled ileal and sigmoid colon segment transfer].

PubMed

Zhang, Dawei; Zhang, Jun; Wang, Huanying; Li, Bin; Zhu, Xiaoxing; Wang, Liying; Wu, Jixiang

2014-03-01

To study the clinical effect of laparoscopic vaginoplasty using pedicled ileal and sigmoid colon segment. From January 2004 to December 2009, 105 cases undergoing laparoscope-assisted vaginoplasty using a vascularized pedicled intestinal flap were studied retrospectively. Operation time, blood loss in operating, bowel movement after operation, postoperation hospital duration, side effect, and artificial vagina were compared between two surgical management. The vaginoplasty were preformed successfully in all 105 cases. There were 48 patients treated by aparoscope-assisted ileal vaginoplasty and 57 patients treated by laparoscope-assisted sigmoid colon vaginoplasty. The values of the operation time [(141 ± 22) minutes versus (159 ± 18) minutes, P = 0.000], blood loss in operating [(42 ± 6) ml versus (83 ± 14) ml, P = 0.000], bowel movement after operation (36 ± 9) hours versus (68 ± 8) hours(P = 0.000), and postoperation hospital duration [(9.8 ± 2.0) days versus (11.1 ± 1.3) days, P = 0.004] in the sigmoid colon vaginoplasty group were longer or higher than those in ileal vaginoplasty group (P < 0.05).No intraoprative complication occurred. There were four postoperative complications: 2 cases with intestinal obstruction in sigmoid colon vaginoplasty group, 1 case with urethral orifice stenosis and 1 case with vaginal-rectal fistula in ileal vaginoplasty group. At follow-up of 6-62 months, all artificial vaginas had a capacity of over two fingers in wideness and 12-15 cm in length. Vaginal discharges resembled a milky white water or mucus without odour. Fifty-five patients with sexual intercourse reported satisfactory results.Six patients complained vaginal stenosis:5 patients in ileal vaginoplasty group and 1 patient in sigmoid colon vaginoplasty group. Laparoscope-assisted vaginoplasty using pedicled ileum or sigmoid colon segment are both the effective ways in forming vagina. The latter management takes more time and blood loss while operating, yet the incidence of vaginal opening contracture appeared to be decreasing trend.

Synchronous volvulus of the sigmoid colon and caecum, a very rare cause of large bowel obstruction.

PubMed

Islam, Shariful; Hosein, Devin; Bheem, Vinoo; Dan, Dilip

2016-10-14

Colonic volvulus usually occurs as a single event that can affect various parts of the colon. The usual sites affected being the sigmoid colon (75%) and the caecum (22%). The phenomenon of multiple sites simultaneously undergoing volvulus is an extremely rare occurrence. Synchronous double colonic volvulus is extremely rare and to the best of our knowledge, this is the 4th reported case of simultaneous sigmoid and caecal volvulus in the English literature. The clinical presentation and the radiological findings are that of large bowel obstruction. Classic radiological findings may not be present or may be overlooked due to its rarity. Treatment of this condition is early surgical intervention to prevent the sequalae of a colonic volvulus and its associated mortality. We report a case of an 80-year-old man with synchronous volvulus of the sigmoid colon and caecum. 2016 BMJ Publishing Group Ltd.

Hyoid Bone and Thyroid Cartilage Metastases from Sigmoid Colon Adenocarcinoma: A Case Report.

PubMed

Bracanovic, Djurdja; Vukovic, Vesna; Janovic, Aleksa; Radosavljevic, Davorin; Rakocevic, Zoran

2017-05-05

Secondary tumours of the hyoid bone and thyroid cartilage are extremely rare. In this paper, we present a case of the hyoid bone and thyroid cartilage metastases in a patient treated for sigmoid colon adenocarcinoma. Four years after sigmoid colon adenocarcinoma was diagnosed and treated with surgery and chemotherapy, the patient developed bone metastases in the left sacroiliac joint and right proximal humerus. Although the patient did not complain of any related symptoms, in a bone scintigraphy the accumulation of Technetium-99m was incidentally detected in the two sites of the anterior neck. On ultrasound examination there were two hyperechoic and heterogeneous masses with calcifications placed in front of the hyoid bone and thyroid cartilage. Computerized tomography demonstrated massive hyoid bone and thyroid cartilage destruction. In patients with progressive sigmoid colon adenocarcinoma, destruction of the hyoid bone and thyroid cartilage could be suspected for metastases.

Stent-Assisted Coil Embolization of a Transverse-Sigmoid Sinus Diverticulum Presenting with Pulsatile Tinnitus.

PubMed

Li, Baomin; Lv, Xianli; Wu, Zhongxue; Cao, Xiangyu; Wang, Jun; Ge, Aili; Liu, Xinfeng; Li, Sheng

When tinnitus is pulse-synchronous, a vascular etiology is suggested. We present a case of persistent and troublesome pulsatile tinnitus caused by a transverse-sigmoid sinus diverticulum that was endovascularly treated with stent-assisted coiling. A 39-yearold woman presented with a 4-year history of progressive pulsatile tinnitus involving the right ear. Slight pulsatile bruit was heard on the right mastoid bone by auscultation. Cerebral angiography demonstrated a diverticulum of the transverse-sigmoid sinus. The procedure was performed with an 8F guiding catheter (Cordis, USA) catheterized into the right sigmoid sinus. The diverticulum was completely coiled following deployment of a 5.5 mm-50 mm Leo stent. This patient awakened without any neurological deficit and with immediate resolution of her tinnitus. This case report describes a stent-assisted coil embolization of venous sinus diverticulum, which provides immediate resolution of pulsatile tinnitus.

RECURRENT EXPLOSIVE ERUPTIONS AND THE ''SIGMOID-TO-ARCADE'' TRANSFORMATION IN THE SUN DRIVEN BY DYNAMICAL MAGNETIC FLUX EMERGENCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Archontis, V.; Hood, A. W.; Tsinganos, K., E-mail: va11@st-andrews.ac.uk

2014-05-10

We report on three-dimensional MHD simulations of recurrent mini coronal mass ejection (CME)-like eruptions in a small active region (AR), which is formed by the dynamical emergence of a twisted (not kink unstable) flux tube from the solar interior. The eruptions develop as a result of the repeated formation and expulsion of new flux ropes due to continuous emergence and reconnection of sheared field lines along the polarity inversion line of the AR. The acceleration of the eruptions is triggered by tether-cutting reconnection at the current sheet underneath the erupting field. We find that each explosive eruption is followed bymore » reformation of a sigmoidal structure and a subsequent ''sigmoid-to-flare arcade'' transformation in the AR. These results might have implications for recurrent CMEs and eruptive sigmoids/flares observations and theoretical studies.« less

A comparison of human cadaver and augmented reality simulator models for straight laparoscopic colorectal skills acquisition training.

PubMed

LeBlanc, Fabien; Champagne, Bradley J; Augestad, Knut M; Neary, Paul C; Senagore, Anthony J; Ellis, Clyde N; Delaney, Conor P

2010-08-01

The aim of this study was to compare the human cadaver model with an augmented reality simulator for straight laparoscopic colorectal skills acquisition. Thirty-five sigmoid colectomies were performed on a cadaver (n = 7) or an augmented reality simulator (n = 28) during a laparoscopic training course. Prior laparoscopic colorectal experience was assessed. Objective structured technical skills assessment forms were completed by trainers and trainees independently. Groups were compared according to technical skills and events scores and satisfaction with training model. Prior laparoscopic experience was similar in both groups. For trainers and trainees, technical skills scores were considerably better on the simulator than on the cadaver. For trainers, generic events score was also considerably better on the simulator than on the cadaver. The main generic event occurring on both models was errors in the use of retraction. The main specific event occurring on both models was bowel perforation. Global satisfaction was better for the cadaver than for the simulator model (p < 0.001). The human cadaver model was more difficult but better appreciated than the simulator for laparoscopic sigmoid colectomy training. Simulator training followed by cadaver training can appropriately integrate simulators into the learning curve and maintain the benefits of both training methodologies. Published by Elsevier Inc.

Comparative evaluation of two dose optimization methods for image-guided, highly-conformal, tandem and ovoids cervix brachytherapy planning

NASA Astrophysics Data System (ADS)

Ren, Jiyun; Menon, Geetha; Sloboda, Ron

2013-04-01

Although the Manchester system is still extensively used to prescribe dose in brachytherapy (BT) for locally advanced cervix cancer, many radiation oncology centers are transitioning to 3D image-guided BT, owing to the excellent anatomy definition offered by modern imaging modalities. As automatic dose optimization is highly desirable for 3D image-based BT, this study comparatively evaluates the performance of two optimization methods used in BT treatment planning—Nelder-Mead simplex (NMS) and simulated annealing (SA)—for a cervix BT computer simulation model incorporating a Manchester-style applicator. Eight model cases were constructed based on anatomical structure data (for high risk-clinical target volume (HR-CTV), bladder, rectum and sigmoid) obtained from measurements on fused MR-CT images for BT patients. D90 and V100 for HR-CTV, D2cc for organs at risk (OARs), dose to point A, conformation index and the sum of dwell times within the tandem and ovoids were calculated for optimized treatment plans designed to treat the HR-CTV in a highly conformal manner. Compared to the NMS algorithm, SA was found to be superior as it could perform optimization starting from a range of initial dwell times, while the performance of NMS was strongly dependent on their initial choice. SA-optimized plans also exhibited lower D2cc to OARs, especially the bladder and sigmoid, and reduced tandem dwell times. For cases with smaller HR-CTV having good separation from adjoining OARs, multiple SA-optimized solutions were found which differed markedly from each other and were associated with different choices for initial dwell times. Finally and importantly, the SA method yielded plans with lower dwell time variability compared with the NMS method.

Modes of Disintegration of Solid Foods in Simulated Gastric Environment

PubMed Central

Kong, Fanbin

2009-01-01

A model stomach system was used to investigate disintegration of various foods in simulated gastric environment. Food disintegration modes and typical disintegration profiles are summarized in this paper. Mechanisms contributing to the disintegration kinetics of different foods were investigated as related to acidity, temperature, and enzymatic effect on the texture and changes in microstructure. Food disintegration was dominated by either fragmentation or erosion, depending on the physical forces acting on food and the cohesive force within the food matrix. The internal cohesive forces changed during digestion as a result of water penetration and acidic and enzymatic hydrolysis. When erosion was dominant, the disintegration data (weight retention vs. disintegration time) may be expressed with exponential, sigmoidal, and delayed-sigmoidal profiles. The different profiles are the result of competition among the rates of water absorption, texture softening, and erosion. A linear-exponential equation was used to describe the different disintegration curves with good fit. Acidity and temperature of gastric juice showed a synergistic effect on carrot softening, while pepsin was the key factor in disintegrating high-protein foods. A study of the change of carrot microstructure during digestion indicated that degradation of the pectin and cell wall was responsible for texture softening that contributed to the sigmoidal profile of carrot disintegration. PMID:20401314

A Survery of the Correlation between Filament Chirality and Sigmoid Handedness

NASA Astrophysics Data System (ADS)

V, A.; Hazra, S.; Martin, S. F.; Martens, P. C.

2017-12-01

Sigmoid regions on the Sun are often the regions that cause Coronal Mass Ejections (CMEs). Large CMEs most often have filaments that erupt with them. This study focuses on the statistical relevance of the shape of the sigmoid and the chirality of the filament residing in these sigmoids. The study further extends to the relation between the directionality of filaments and the Earth-directed CMEs. Sigmoid data from Savcheva et al. (2014) between 2007 and 2012 and a compilation of data using the HEK Sigmoid Sniffer (Martens et al. 2012) along with Hinode XRT Soft X-ray images were used for analyzing data between 2013 and 2017. Hence this dataset consists of almost one solar cycle of data. A similar study done previously by Martens et al. (2013) analysed data for a solar cycle using an Advanced Automated Filament Detection & Characterization Code (Bernasconi, Rust & Hakim 2005). Considering that automated chirality detection is not foolproof, we present this study which uses manual determination of chirality for accuracy using high resolution chromospheric images. Mainly full disk images of soft X-ray obtained from Hinode XRT (X-Ray Telescope) have been used to find and ensure the S or Z shape of sigmoids. H-alpha images obtained from BBSO and Kanzelhohe Solar Observatory (KSO) are used in determining the chirality of filaments. The resolutions of BBSO and KSO data are 1k and 4k respectively. A comparison of the analysis of the chirality of filaments using both data will be presented. Although KSO gives a 4k resolution, it is still difficult to determine the chirality of small filaments. For this reason, high resolution images of H-alpha chromospheric filaments obtained from Helio Research and Solar Observing Optical Network (SOON) have been used for further analysis of chirality of those filaments that were undeterminable using the BBSO or KSO full disk images. The results of the comparison using the different resolutions are shown. The results of the correlation between sigmoid shape and filament chirality are also shown. Further, these results are used in determining the correlation with Earth directed CMEs and those that cause geo-magnetic storms. Savacheva, A. S., McKillop, S. C., McCauley, P. I., et al., 2014, 289Bernasconi, P. N., Rust, D. M., & Hakim, D., 2005, Sol. Phys., 228, 97 Martens, P., Yeates, A., & Pillai, K., 2013, IAU, 3000

Linear and Nonlinear Viscoelastic Modeling of Aorta and Carotid Pressure-Area Dynamics under in vivo and ex vivo Conditions

PubMed Central

Valdez-Jasso, Daniela; Bia, Daniel; Zócalo, Yanina; Armentano, Ricardo L.; Haider, Mansoor A.; Olufsen, Mette S.

2013-01-01

A better understanding of the biomechanical properties of the arterial wall provides important insight into arterial vascular biology under normal (healthy) and pathological conditions. This insight has potential to improve tracking of disease progression and to aid in vascular graft design and implementation. In this study, we use linear and nonlinear viscoelastic models to predict biomechanical properties of the thoracic descending aorta and the carotid artery under ex vivo and in vivo conditions in ovine and human arteries. Models analyzed include a four-parameter (linear) Kelvin viscoelastic model and two five-parameter nonlinear viscoelastic models (an arctangent and a sigmoid model) that relate changes in arterial blood pressure to the vessel cross-sectional area (via estimation of vessel strain). These models were developed using the framework of Quasilinear Viscoelasticity (QLV) theory and were validated using measurements from the thoracic descending aorta and the carotid artery obtained from human and ovine arteries. In vivo measurements were obtained from ten ovine aortas and ten human carotid arteries. Ex vivo measurements (from both locations) were made in eleven male Merino sheep. Biomechanical properties were obtained through constrained estimation of model parameters. To further investigate the parameter estimates we computed standard errors and confidence intervals and we used analysis of variance to compare results within and between groups. Overall, our results indicate that optimal model selection depends on the arterial type. Results showed that for the thoracic descending aorta (under both experimental conditions) the best predictions were obtained with the nonlinear sigmoid model, while under healthy physiological pressure loading the carotid arteries nonlinear stiffening with increasing pressure is negligible, and consequently, the linear (Kelvin) viscoelastic model better describes the pressure-area dynamics in this vessel. Results comparing biomechanical properties show that the Kelvin and sigmoid models were able to predict the zero-pressure vessel radius; that under ex vivo conditions vessels are more rigid, and comparatively, that the carotid artery is stiffer than the thoracic descending aorta; and that the viscoelastic gain and relaxation parameters do not differ significantly between vessels or experimental conditions. In conclusion, our study demonstrates that the proposed models can predict pressure-area dynamics and that model parameters can be extracted for further interpretation of biomechanical properties. PMID:21203846

Rapid totally diverting loop sigmoid colostomy with noncontaminating rectal irrigation.

PubMed

Sachatello, C R; Maull, K I

1977-08-01

Loop sigmoid colostomy employing a stapling device and catheter irrigation of the distal segment is less time-consuming and has lest potential for contamination than the standard double-barrel colostomy. Unlike the standard loop colostomy, it is totally diverting.

SEX REASSIGNMENT SURGERY WITH LAPAROSCOPIC SIGMOID COLON VAGINOPLASTY IN A MALE TO FEMALE TRANSSEXUAL: A CASE REPORT.

PubMed

Ichihara, Koji; Masumori, Naoya

2016-01-01

We herein report and discuss our first experience about a sex reassignment surgery (SRS) with laparoscopic sigmoid colon vaginoplasty for a 40s male to female gender identity disorder. SRS for this subject included bilateral orchiectomy, penectomy, clitoroplasty, vaginoplasty, and vulvoplasty. About 20 cm of the sigmoid colon was harvested laparoscopicaly for the neovagina. Total operating time was about 9 hours, and the estimated blood loss was 900 ml without transfusion. There was no trouble during the postoperative course, and a sufficient length of vagina has been maintained.

Comparative study of collagen deposition in the colon wall of patients operated for sigmoid diverticular disease.

PubMed

Pantaroto, Mário; Lopes Filho, Gaspar de Jesus; Pinto, Clovis Antonio Lopes; Antico Filho, Armando

2015-10-01

To investigate the deposition of collagen in the colon wall of patients with sigmoid diverticulitis. Samples of sigmoid tissue from 15 patients (disease group), seven men and eight women aged 37-77 years who underwent surgery for the treatment of diverticulitis, were selected. For the control group, specimens from five patients, three men and two women aged 19-58 years undergoing emergency surgery for sigmoid trauma were selected. These subjects had no associated diseases. The histological study of the surgical specimens was performed by staining with hematoxylin-eosin and picrosirius and using a histochemical method for collagen quantification. Collagen deposition in the colon wall in terms of area (F), glandular epithelium (E) and total area was significantly higher in the disease group compared to control (p=0.003, p=0.026 and p=0.010, respectively). The collagen volume fraction (F fraction) and muscle tissue (M fraction) were also significantly higher compared to control (p=0.044 and p=0.026, respectively). The muscle (M area) and volume fraction of glandular epithelium (E fraction) did not differ significantly between the two groups, (p=0.074 and p=1.000, respectively). In this study, collagen deposition in the colon wall of the patients operated for sigmoid diverticulitis was higher compared to patients without the disease.

Preparation of nanobubbles for ultrasound imaging and intracelluar drug delivery.

PubMed

Wang, Ye; Li, Xiang; Zhou, Yan; Huang, Pengyu; Xu, Yuhong

2010-01-15

Echogenic bubble formulations have wide applications in both disease diagnosis and therapy. In the current study, nanobubbles were prepared and the contrast agent function was evaluated in order to study the nanosized bubble's property for ultrasonic imaging. Coumarin-6 as a model drug was loaded into nanobubbles to investigate the drug delivery potential to cells. The results showed that the nanobubbles composed of 1% of Tween 80, and 3 mg/ml of lipid worked well as an ultrasonic contrast agent by presenting a contrast effect in the liver region in vivo. The drug-loaded nanobubbles could enhance drug delivery to cells significantly, and the process was analyzed by sigmoidally fitting the pharmacokinetic curve. It can be concluded that the nanobubble formulation is a promising approach for both ultrasound imaging and drug delivery enhancing.

Double Arc Instability in the Solar Corona

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishiguro, N.; Kusano, K., E-mail: n-ishiguro@isee.nagoya-u.ac.jp

The stability of the magnetic field in the solar corona is important for understanding the causes of solar eruptions. Although various scenarios have been suggested to date, the tether-cutting reconnection scenario proposed by Moore et al. is one of the widely accepted models to explain the onset process of solar eruptions. Although the tether-cutting reconnection scenario proposes that the sigmoidal field formed by internal reconnection is the magnetic field in the pre-eruptive state, the stability of the sigmoidal field has not yet been investigated quantitatively. In this paper, in order to elucidate the stability problem of the pre-eruptive state, wemore » developed a simple numerical analysis in which the sigmoidal field is modeled by a double arc electric current loop and its stability is analyzed. As a result, we found that the double arc loop is more easily destabilized than the axisymmetric torus, and it becomes unstable even if the external field does not decay with altitude, which is in contrast to the axisymmetric torus instability. This suggests that tether-cutting reconnection may well work as the onset mechanism of solar eruptions, and if so, the critical condition for eruption under a certain geometry may be determined by a new type of instability rather than by the torus instability. Based on them, we propose a new type of instability called double arc instability (DAI). We discuss the critical conditions for DAI and derive a new parameter κ , defined as the product of the magnetic twist and the normalized flux of the tether-cutting reconnection.« less

A Mathematical Model of Levodopa Medication Effect on Basal Ganglia in Parkinson's Disease: An Application to the Alternate Finger Tapping Task.

PubMed

Baston, Chiara; Contin, Manuela; Calandra Buonaura, Giovanna; Cortelli, Pietro; Ursino, Mauro

2016-01-01

Malfunctions in the neural circuitry of the basal ganglia (BG), induced by alterations in the dopaminergic system, are responsible for an array of motor disorders and milder cognitive issues in Parkinson's disease (PD). Recently Baston and Ursino (2015a) presented a new neuroscience mathematical model aimed at exploring the role of basal ganglia in action selection. The model is biologically inspired and reproduces the main BG structures and pathways, modeling explicitly both the dopaminergic and the cholinergic system. The present work aims at interfacing this neurocomputational model with a compartmental model of levodopa, to propose a general model of medicated Parkinson's disease. Levodopa effect on the striatum was simulated with a two-compartment model of pharmacokinetics in plasma joined with a motor effect compartment. The latter is characterized by the levodopa removal rate and by a sigmoidal relationship (Hill law) between concentration and effect. The main parameters of this relationship are saturation, steepness, and the half-maximum concentration. The effect of levodopa is then summed to a term representing the endogenous dopamine effect, and is used as an external input for the neurocomputation model; this allows both the temporal aspects of medication and the individual patient characteristics to be simulated. The frequency of alternate tapping is then used as the outcome of the whole model, to simulate effective clinical scores. Pharmacokinetic-pharmacodynamic modeling was preliminary performed on data of six patients with Parkinson's disease (both "stable" and "wearing-off" responders) after levodopa standardized oral dosing over 4 h. Results show that the model is able to reproduce the temporal profiles of levodopa in plasma and the finger tapping frequency in all patients, discriminating between different patterns of levodopa motor response. The more influential parameters are the Hill coefficient, related with the slope of the effect sigmoidal relationship, the drug concentration at half-maximum effect, and the drug removal rate from the effect compartment. The model can be of value to gain a deeper understanding on the pharmacokinetics and pharmacodynamics of the medication, and on the way dopamine is exploited in the neural circuitry of the basal ganglia in patients at different stages of the disease progression.

A Mathematical Model of Levodopa Medication Effect on Basal Ganglia in Parkinson's Disease: An Application to the Alternate Finger Tapping Task

PubMed Central

Baston, Chiara; Contin, Manuela; Calandra Buonaura, Giovanna; Cortelli, Pietro; Ursino, Mauro

2016-01-01

Malfunctions in the neural circuitry of the basal ganglia (BG), induced by alterations in the dopaminergic system, are responsible for an array of motor disorders and milder cognitive issues in Parkinson's disease (PD). Recently Baston and Ursino (2015a) presented a new neuroscience mathematical model aimed at exploring the role of basal ganglia in action selection. The model is biologically inspired and reproduces the main BG structures and pathways, modeling explicitly both the dopaminergic and the cholinergic system. The present work aims at interfacing this neurocomputational model with a compartmental model of levodopa, to propose a general model of medicated Parkinson's disease. Levodopa effect on the striatum was simulated with a two-compartment model of pharmacokinetics in plasma joined with a motor effect compartment. The latter is characterized by the levodopa removal rate and by a sigmoidal relationship (Hill law) between concentration and effect. The main parameters of this relationship are saturation, steepness, and the half-maximum concentration. The effect of levodopa is then summed to a term representing the endogenous dopamine effect, and is used as an external input for the neurocomputation model; this allows both the temporal aspects of medication and the individual patient characteristics to be simulated. The frequency of alternate tapping is then used as the outcome of the whole model, to simulate effective clinical scores. Pharmacokinetic-pharmacodynamic modeling was preliminary performed on data of six patients with Parkinson's disease (both “stable” and “wearing-off” responders) after levodopa standardized oral dosing over 4 h. Results show that the model is able to reproduce the temporal profiles of levodopa in plasma and the finger tapping frequency in all patients, discriminating between different patterns of levodopa motor response. The more influential parameters are the Hill coefficient, related with the slope of the effect sigmoidal relationship, the drug concentration at half-maximum effect, and the drug removal rate from the effect compartment. The model can be of value to gain a deeper understanding on the pharmacokinetics and pharmacodynamics of the medication, and on the way dopamine is exploited in the neural circuitry of the basal ganglia in patients at different stages of the disease progression. PMID:27378881

Stable modeling based control methods using a new RBF network.

PubMed

Beyhan, Selami; Alci, Musa

2010-10-01

This paper presents a novel model with radial basis functions (RBFs), which is applied successively for online stable identification and control of nonlinear discrete-time systems. First, the proposed model is utilized for direct inverse modeling of the plant to generate the control input where it is assumed that inverse plant dynamics exist. Second, it is employed for system identification to generate a sliding-mode control input. Finally, the network is employed to tune PID (proportional + integrative + derivative) controller parameters automatically. The adaptive learning rate (ALR), which is employed in the gradient descent (GD) method, provides the global convergence of the modeling errors. Using the Lyapunov stability approach, the boundedness of the tracking errors and the system parameters are shown both theoretically and in real time. To show the superiority of the new model with RBFs, its tracking results are compared with the results of a conventional sigmoidal multi-layer perceptron (MLP) neural network and the new model with sigmoid activation functions. To see the real-time capability of the new model, the proposed network is employed for online identification and control of a cascaded parallel two-tank liquid-level system. Even though there exist large disturbances, the proposed model with RBFs generates a suitable control input to track the reference signal better than other methods in both simulations and real time. Copyright © 2010 ISA. Published by Elsevier Ltd. All rights reserved.

Comparison of dose volume parameters evaluated using three forward planning – optimization techniques in cervical cancer brachytherapy involving two applicators

PubMed Central

Basu-Roy, Somapriya; Kar, Sanjay Kumar; Das, Sounik; Lahiri, Annesha

2017-01-01

Purpose This study is intended to compare dose-volume parameters evaluated using different forward planning- optimization techniques, involving two applicator systems in intracavitary brachytherapy for cervical cancer. It looks for the best applicator-optimization combination to fulfill recommended dose-volume objectives in different high-dose-rate (HDR) fractionation schedules. Material and methods We used tandem-ring and Fletcher-style tandem-ovoid applicator in same patients in two fractions of brachytherapy. Six plans were generated for each patient utilizing 3 forward optimization techniques for each applicator used: equal dwell weight/times (‘no optimization’), ‘manual dwell weight/times’, and ‘graphical’. Plans were normalized to left point A and dose of 8 Gy was prescribed. Dose volume and dose point parameters were compared. Results Without graphical optimization, maximum width and thickness of volume enclosed by 100% isodose line, dose to 90%, and 100% of clinical target volume (CTV); minimum, maximum, median, and average dose to both rectum and bladder are significantly higher with Fletcher applicator. Even if it is done, dose to both points B, minimum dose to CTV, and treatment time; dose to 2 cc (D2cc) rectum and rectal point etc.; D2cc, minimum, maximum, median, and average dose to sigmoid colon; D2cc of bladder remain significantly higher with this applicator. Dose to bladder point is similar (p > 0.05) between two applicators, after all optimization techniques. Conclusions Fletcher applicator generates higher dose to both CTV and organs at risk (2 cc volumes) after all optimization techniques. Dose restriction to rectum is possible using graphical optimization only during selected HDR fractionation schedules. Bladder always receives dose higher than recommended, and 2 cc sigmoid colon always gets permissible dose. Contrarily, graphical optimization with ring applicators fulfills all dose volume objectives in all HDR fractionations practiced. PMID:29204164

SUNSPOT ROTATION AS A DRIVER OF MAJOR SOLAR ERUPTIONS IN THE NOAA ACTIVE REGION 12158

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vemareddy, P.; Ravindra, B.; Cheng, X., E-mail: vemareddy@iiap.res.in

We studied the development conditions of sigmoid structure under the influence of the magnetic non-potential characteristics of a rotating sunspot in the active region (AR) 12158. Vector magnetic field measurements from the Helioseismic Magnetic Imager and coronal EUV observations from the Atmospheric Imaging Assembly reveal that the erupting inverse-S sigmoid had roots at the location of the rotating sunspot. The sunspot rotates at a rate of 0°–5° h{sup −1} with increasing trend in the first half followed by a decrease. The time evolution of many non-potential parameters had a good correspondence with the sunspot rotation. The evolution of the ARmore » magnetic structure is approximated by a time series of force-free equilibria. The non-linear force-free field magnetic structure around the sunspot manifests the observed sigmoid structure. Field lines from the sunspot periphery constitute the body of the sigmoid and those from the interior overlie the sigmoid, similar to a flux rope structure. While the sunspot was rotating, two major coronal mass ejection eruptions occurred in the AR. During the first (second) event, the coronal current concentrations were enhanced (degraded), consistent with the photospheric net vertical current; however, magnetic energy was released during both cases. The analysis results suggest that the magnetic connections of the sigmoid are driven by the slow motion of sunspot rotation, which transforms to a highly twisted flux rope structure in a dynamical scenario. Exceeding the critical twist in the flux rope probably leads to the loss of equilibrium, thus triggering the onset of the two eruptions.« less

Primary Total Laparoscopic Sigmoid Vaginoplasty in Transgender Women with Penoscrotal Hypoplasia: A Prospective Cohort Study of Surgical Outcomes and Follow-Up of 42 Patients.

PubMed

Bouman, Mark-Bram; van der Sluis, Wouter B; Buncamper, Marlon E; Özer, Müjde; Mullender, Margriet G; Meijerink, Wilhelmus J H J

2016-10-01

In young transgender women previously treated with puberty-suppressing hormones, penoscrotal hypoplasia can make penoscrotal inversion vaginoplasty unfeasible. The aim of this study was to prospectively assess surgical outcomes and follow-up of total laparoscopic sigmoid vaginoplasty as primary reconstruction in a cohort of transgender women with penoscrotal hypoplasia. Baseline demographics, surgical characteristics, and intraoperative and postoperative complications of all performed total laparoscopic sigmoid vaginoplasty procedures were prospectively recorded. From November of 2007 to July of 2015, 42 transgender women underwent total laparoscopic sigmoid vaginoplasty as primary vaginal reconstruction. The mean age at the time of surgery was 21.1 ± 4.7 years. Mean follow-up time was 3.2 ± 2.1 years. The mean operative duration was 210 ± 44 minutes. There were no conversions to laparotomy. One rectal perforation was recognized during surgery and immediately oversewn without long-term consequences. The mean length of hospitalization was 5.7 ± 1.1 days. One patient died as a result of an extended-spectrum beta-lactamase-positive necrotizing fasciitis leading to septic shock, with multiorgan failure. Direct postoperative complications that needed laparoscopic reoperation occurred in three cases (7.1 percent). In seven cases (17.1 percent), long-term complications needed a secondary correction. After 1 year, all patients had a functional neovagina with a mean depth of 16.3 ± 1.5 cm. Total laparoscopic sigmoid vaginoplasty seems to have a similar complication rate as other types of elective laparoscopic colorectal surgery. Primary total laparoscopic sigmoid vaginoplasty is a feasible gender-confirming surgical technique with good functional outcomes for transgender women with penoscrotal hypoplasia. Therapeutic, IV.

Colonic involvement in celiac disease and possible implications of the sigmoid mucosa organ culture in its diagnosis.

PubMed

Picarelli, Antonio; Di Tola, Marco; Borghini, Raffaele; Isonne, Claudia; Saponara, Annarita; Marino, Mariacatia; Casale, Rossella; Tiberti, Antonio; Pica, Roberta; Donato, Giuseppe; Frieri, Giuseppe; Corazziari, Enrico

2013-10-01

Celiac disease (CD), a systemic autoimmune disorder that typically involves duodenal mucosa, can also affect other intestinal areas. Duodenal and oral mucosa organ culture has already been demonstrated as a reliable procedure to identify CD. The present study investigated gluten-dependent immunological activation of colonic mucosa in CD patients. We took advantage of the numerous colonoscopies performed for various clinical conditions or only for defensive medicine. Forty-four patients with gastrointestinal symptoms or in need of colorectal cancer screening were divided into patients with serum anti-endomysium (EMA) and anti-tissue transglutaminase (anti-tTG) antibody positive results (Group A), patients with serum antibody negative results (Group B), and patients with inflammatory bowel disease (IBD) (Group C). The autoantibodies EMA and anti-tTG were evaluated in supernatants of cultured sigmoid and duodenal biopsies from patients on a gluten-containing diet. In Group A, EMA and anti-tTG resulted positive in all duodenal culture supernatants. In sigmoid culture supernatants, EMA and anti-tTG were detected in 12/16 (75 %) and 13/16 (81.3 %) patients, respectively. In Group B, none of the 17 patients showed EMA and anti-tTG positive results in both duodenal and sigmoid cultures. In Group C, all 11 patients presented EMA negative results in sigmoid cultures. Only in one patient, anti-tTG were detectable in the sigmoid culture supernatant, as expected in cases of IBD. Data confirm that the gluten-dependent immunological activation affects more intestinal tracts with different degrees of involvement, suggesting that the organ culture of colonic biopsies could represent a new tool to opportunistically detect CD.

Hand-assisted versus straight laparoscopic sigmoid colectomy on a training simulator: what is the difference? A stepwise comparison of hand-assisted versus straight laparoscopic sigmoid colectomy performance on an augmented reality simulator.

PubMed

Leblanc, Fabien; Delaney, Conor P; Ellis, Clyde N; Neary, Paul C; Champagne, Bradley J; Senagore, Anthony J

2010-12-01

We hypothesized that simulator-generated metrics and intraoperative errors may be able to differentiate the technical differences between hand-assisted laparoscopic (HAL) and straight laparoscopic (SL) approaches. Thirty-eight trainees performed two laparoscopic sigmoid colectomies on an augmented reality simulator, randomly starting by a SL (n = 19) or HAL (n = 19) approach. Both approaches were compared according to simulator-generated metrics, and intraoperative errors were collected by faculty. Sixty-four percent of surgeons were experienced (>50 procedures) with open colon surgery. Fifty-five percent and 69% of surgeons were inexperienced (<10 procedures) with SL and HAL colon surgery, respectively. Time (P < 0.001), path length (P < 0.001), and smoothness (P < 0.001) were lower with the HAL approach. Operative times for sigmoid and splenic flexure mobilization and for the colorectal anastomosis were significantly shorter with the HAL approach. Time to control the vascular pedicle was similar between both approaches. Error rates were similar between both approaches. Operative time, path length, and smoothness correlated directly with the error rate for the HAL approach. In contrast, error rate inversely correlated with the operative time for the SL approach. A HAL approach for sigmoid colectomy accelerated colonic mobilization and anastomosis. The difference in correlation between both laparoscopic approaches and error rates suggests the need for different skills to perform the HAL and the SL sigmoid colectomy. These findings may explain the preference of some surgeons for a HAL approach early in the learning of laparoscopic colorectal surgery.

Rotating Magnetic Structures Associated with a Quasi-circular Ribbon Flare

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Haidong; Jiang, Yunchun; Yang, Jiayan

We present the detection of a small eruption and the associated quasi-circular ribbon flare during the emergence of a bipole occurring on 2015 February 3. Under a fan dome, a sigmoid was rooted in a single magnetic bipole, which was encircled by negative polarity. The nonlinear force-free field extrapolation shows the presence of twisted field lines, which can represent a sigmoid structure. The rotation of the magnetic bipole may cause the twisting of magnetic field lines. An initial brightening appeared at one of the footpoints of the sigmoid, where the positive polarity slides toward a nearby negative polarity field region.more » The sigmoid displayed an ascending motion and then interacted intensively with the spine-like field. This type of null point reconnection in corona led to a violent blowout jet, and a quasi-circular flare ribbon was also produced. The magnetic emergence and rotational motion are the main contributors to the energy buildup for the flare, while the cancellation and collision might act as a trigger.« less

A Rare Case of Splenic Torsion with Sigmoid Volvulus in a 14-Year-Old Girl.

PubMed

Ahmadi, Hamid; Tehrani, Mahdieh Mohammad Khan

2016-01-01

Wandering spleen is an uncommon entity in adults and has been described only rarely with sigmoid volvulus, that rarely affects children and adolescents. It is usually described in adults.Wandering spleen characterized by the abnormal location of the spleen, caused by incomplete fusion of the four primary splenic ligaments, allowing the spleen to be mobile within the abdomen.The wandering spleen can lead to torsion and subsequent splenic infarction or rupture. Clinical suspicion plus urgent investigation and intervention are important. We present a rare clinical case of acute abdomen due to torsion of wandering spleen and volvulus of sigmoid in a 14-year-old girl presented with painful periumbilical mass. Detorsion of sigmoid occurred while undergoing exploratory laparotomy and splenectomy was performed. The possibility of torsion and its complication like gastric, pancreas tail and colon volvulus should be kept in mind in the differential diagnosis of the acute abdomen to avoid serious complications.

Prospective analysis of percutaneous endoscopic colostomy at a tertiary referral centre.

PubMed

Baraza, W; Brown, S; McAlindon, M; Hurlstone, P

2007-11-01

Percutaneous endoscopic colostomy (PEC) is an alternative to surgery in selected patients with recurrent sigmoid volvulus, recurrent pseudo-obstruction or severe slow-transit constipation. A percutaneous tube acts as an irrigation or decompressant channel, or as a mode of sigmoidopexy. This prospective study evaluated the safety and efficacy of this procedure at a single tertiary referral centre. Nineteen patients with recurrent sigmoid volvulus, ten with idiopathic slow-transit constipation and four with pseudo-obstruction underwent PEC. The tube was left in place indefinitely in those with recurrent sigmoid volvulus or constipation, whereas in patients with pseudo-obstruction it was left in place for a variable period of time, depending on symptoms. Thirty-five procedures were performed in 33 patients. Three patients developed peritonitis, of whom one died, and ten patients had minor complications. Symptoms resolved in 26 patients. This large prospective study has confirmed the value of PEC in the treatment of recurrent sigmoid volvulus and pseudo-obstruction in high-risk surgical patients. Copyright (c) 2007 British Journal of Surgery Society Ltd.

New and emerging treatments for the prevention of recurrent diverticulitis

PubMed Central

Martin, Sean T; Stocchi, Luca

2011-01-01

Sigmoid diverticulitis is a common benign condition which carries significant morbidity and socioeconomic burden. This article describes the management of sigmoid diverticulitis with a focus on indications for surgical intervention. The mainstay of management of uncomplicated diverticulitis is broad-spectrum antibiotic therapy. The old surgical dictum that two episodes of sigmoid diverticulitis warranted surgical intervention has been challenged by recently published data. Surgery for diverticulitis thus needs to be tailored to suit individual presentation; patients presenting with recurrent diverticulitis, severe symptoms or debilitating disease impacting patient’s quality of life mandate surgical intervention. Complicated diverticular disease typically prompts intervention to resect a diseased, strictured sigmoid colon, fistulizing disease, or a life-threatening colonic perforation. Laterally, minimally invasive surgery has been utilized in the management of this disease and recent data suggests that localized colonic perforation may be managed by laparoscopic peritoneal lavage, without resection. This review focuses discussion on available evidence for contemporary surgical and nonoperative management of diverticulitis. PMID:22016581

Non-Potential Magnetic Fields and Magnetic Reconnection In Low Collisional Plasmas-Discovery of Solar EUV Mini-Sigmoids and Development of Novel In-Space Propulsion Systems

NASA Astrophysics Data System (ADS)

Chesny, David

Magnetic reconnection is the source of many of the most powerful explosions of astrophysical plasmas in the universe. Blazars, magnetars, stellar atmospheres, and planetary magnetic fields have all been shown to be primary sites of strong reconnection events. For studying the fundamental physics behind this process, the solar atmosphere is our most accessible laboratory setting. Magnetic reconnection resulting from non-potential fields leads to plasma heating and particle acceleration, often in the form of explosive activity, contributing to coronal heating and the solar wind. Large-scale non-potential (sigmoid) fields in the solar atmosphere are poorly understood due to their crowded neighborhoods. For the first time, small-scale, non-potential loop structures have been observed in quiet Sun EUV observations. Fourteen unique mini-sigmoid events and three diffuse non-potential loops have been discovered, suggesting a multi-scaled self-similarity in the sigmoid formation process. These events are on the order of 10 arcseconds in length and do not appear in X-ray emissions, where large-scale sigmoids are well documented. We have discovered the first evidence of sigmoidal structuring in EUV bright point phenomena, which are prolific events in the solar atmosphere. Observations of these mini-sigmoids suggest that they are being formed via tether-cutting reconnection, a process observed to occur at active region scales. Thus, tether-cutting is suggested to be ubiquitous throughout the solar atmosphere. These dynamics are shown to be a function of the free magnetic energy in the quiet Sun network. Recently, the reconnection process has been reproduced in Earth-based laboratory tokamaks. Easily achievable magnetic field configurations can induce reconnection and result in ion acceleration. Here, magnetic reconnection is utilized as the plasma acceleration mechanism for a theoretical propulsion system. The theory of torsional spine reconnection is shown to result in ion velocities of > 3000 km s-1 and thrusts on the order of 3-15 N. As current in-use ion propulsion technology can only achieve ˜ 30 km s-1, the proposed design can substantially increase thrust on a spacecraft and provide for fast manned interplanetary travel.

Endovascular Treatment of Pulsatile Tinnitus by Sigmoid Sinus Aneurysm: Technical Note and Review of the Literature.

PubMed

Cuellar, Hugo; Maiti, Tanmoy; Patra, Devi Prasad; Savardekar, Amey; Sun, Hai; Nanda, Anil

2018-05-01

Pulse-synchronous tinnitus is rare, and it almost always points toward a vascular pathology. We encountered a 56-year-old patient presenting with a 3-month history of right-side tinnitus who was found to have a sigmoid sinus aneurysm after initial imaging. The patient was managed successfully with dual endovascular access and stent placement across the aneurysm, with a subsequent complete symptomatic relief. Description of the endovascular management of sigmoid sinus aneurysm is not infrequent in the literature. This report provides a brief review of the available literature specifically addressing the management strategies. Copyright © 2018 Elsevier Inc. All rights reserved.

Cation activation of the pig kidney sodium pump: transmembrane allosteric effects of sodium.

PubMed Central

Karlish, S J; Stein, W D

1985-01-01

We have studied activation by Na or Rb ions of different transport modes of the Na-K pump, using phospholipid vesicles reconstituted with pig kidney Na-K-ATPase. The shape of the activation curves, sigmoid or quasi-hyperbolic, depends on the nature of the cation at the opposite surface and not on the specific mode of transport. ATP-dependent Na uptake into K-containing vesicles (Na-K exchange) is activated by cytoplasmic Na along a highly sigmoid curve in the absence of extracellular Na (Hill number, nH = 1.9). Activation displays progressively less-sigmoid curves as extracellular Na is raised to 150 mM (nH = 1.2). The maximal rate of the Na-K exchange is not affected. Na is not transported from the extracellular face by the pump in the presence of excess extracellular K, and the transmembrane effects of the extracellular Na are therefore 'allosteric' in nature. ATP-dependent Na-Na exchange (Lee & Blostein, 1980) and classical ATP-plus-ADP-dependent Na-Na exchange are activated by cytoplasmic Na along hyperbolic curves. ATP-dependent Na uptake into Tris-containing vesicles is activated by cytoplasmic Na along a somewhat sigmoidal curve. (ATP + Pi)-dependent Rb-Rb exchange is activated by cytoplasmic and extracellular Rb along strictly hyperbolic curves. The same applies for Rb-Rb exchange in the presence or absence of ATP or Pi alone. The presence of a high concentration of extracellular Na together with extracellular Rb induces a sigmoidal activation by cytoplasmic Rb of (ATP + Pi)-dependent Rb-Rb exchange (nH = 1.45) but does not affect the maximal rate of exchange. Slow passive Rb fluxes through the pump observed in the absence of other pump ligands (see Karlish & Stein, 1982 alpha) are activated by cytoplasmic Rb along a strictly hyperbolic curve with extracellular Rb, nH = 1.0 (Rb-Rb exchange), along a strongly sigmoid curve with extracellular Na, nH = 1.5 (Rb-Na exchange), and along less-sigmoid curves with extracellular Tris, nH = 1.24 (net Rb flux) or extracellular Li, nH = 1.2 (Rb-Li exchange). Activation of the passive Rb fluxes by extracellular Rb is hyperbolic in the presence of cytoplasmic Rb, Li or Tris but is sigmoid in the presence of cytoplasmic Na (nH = 1.36). Inhibition by cytoplasmic Na of passive Rb fluxes from the cytoplasmic to the extracellular face of the pump depends on the nature of the cation at the extracellular surface.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2582111

Management of sigmoid volvulus: options and prognosis.

PubMed

Maddah, Ghodratollah; Kazemzadeh, Gholam Hossein; Abdollahi, Abbas; Bahar, Mostafa Mehrabi; Tavassoli, Alireza; Shabahang, Hossein

2014-01-01

To describe the management of sigmoid volvulus with reference to the type of surgical procedures performed and to determine the prognosis of sigmoid volvulus. A case series. Ghaem Hospital of Mashhad, University of Medical Sciences, Mashhad, Iran, from 1996 to 2008. A total of 944 cases of colon obstruction were reviewed. Demographic, laboratory and treatment results, mortality and complications were recorded. The data was analyzed using descriptive statistics as frequency and percentage for the qualitative variables and mean and standard deviation values for the quantitative variables. Also chisquare and Fisher's exact test were used for the association between the qualitative variables. SPSS statistical software (version 18) was used for the data analysis. In all patients except those with symptoms or signs of gangrenous bowel, a long rectal tube was inserted via the rectosigmoidoscope which was successful in 80 (36.87%) cases. Rectosigmoidoscopic detorsion was unsuccessful in 137 (63.13%) patients, who underwent an emergent laparotomy. The surgical procedures performed in these cases were resection and primary anastomosis in 40 (29.1%), Mikulicz procedure in 9 (6.6%), laparotomy detorsion in 37 (27.01%), Hartmann procedure in 47 (34.3%), mesosigmoidoplasty in 3 (2.19%) patients and total colectomy in one (0.73%) case. The overall mortality was 9.8% (22) patients. In sigmoid volvulus, the most important determinant of patient outcome is bowel viability. The initial treatment of sigmoid colon volvulus is sigmoidoscopy with rectal tube placement.

Transabdominal Ultrasound Colonography for Detection of Colorectal Neoplasms: Initial Clinical Experience.

PubMed

Liu, Jin-Ya; Chen, Li-Da; Xu, Jian-Bo; Wu, Hui; Ye, Jin-Ning; Zhang, Xin-Hua; Xie, Xiao-Yan; Wang, Wei; Lu, Ming-De

2017-10-01

We investigated the feasibility of using ultrasound colonography (USC) to visualize the healthy colon and rectum and detect colorectal polyps. Eight healthy volunteers underwent USC after standard bowel preparation. The feasibility and image quality of USC in different segments were evaluated. Then, USC was conducted on eight patients with known colonic neoplasms using colonoscopy as the reference standard. For volunteers, USC examinations were successfully performed on four (50.0%) ascending, three (37.5%) transverse and eight (100%) descending colons, as well as all sigmoid colons and rectums. One of four (25.0%) ascending, two of eight (25.0%) descending and all sigmoid colons and rectums were well visualized and free of artifacts. For patients, colonoscopy revealed that eight patients had 17 neoplasms in the distal sigmoid colon and rectum, which included 3 lesions ≤5 mm, 3 lesions 6-9 mm and 11 lesions ≥10 mm. USC visualized 12 of 17 (70.6%) neoplasms. Lesion detection by USC was 0% (0/3), 33.3% (1/3) and 100% (11/11) for neoplasms ≤5, 6-9 mm and ≥10 mm in size. USC can visualize the sigmoid colon and rectum well and detect distal sigmoid and rectal neoplasms ≥10 mm in diameter. Copyright © 2017 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Edge Sharpness Assessment by Parametric Modeling: Application to Magnetic Resonance Imaging.

PubMed

Ahmad, R; Ding, Y; Simonetti, O P

2015-05-01

In biomedical imaging, edge sharpness is an important yet often overlooked image quality metric. In this work, a semi-automatic method to quantify edge sharpness in the presence of significant noise is presented with application to magnetic resonance imaging (MRI). The method is based on parametric modeling of image edges. First, an edge map is automatically generated and one or more edges-of-interest (EOI) are manually selected using graphical user interface. Multiple exclusion criteria are then enforced to eliminate edge pixels that are potentially not suitable for sharpness assessment. Second, at each pixel of the EOI, an image intensity profile is read along a small line segment that runs locally normal to the EOI. Third, the profiles corresponding to all EOI pixels are individually fitted with a sigmoid function characterized by four parameters, including one that represents edge sharpness. Last, the distribution of the sharpness parameter is used to quantify edge sharpness. For validation, the method is applied to simulated data as well as MRI data from both phantom imaging and cine imaging experiments. This method allows for fast, quantitative evaluation of edge sharpness even in images with poor signal-to-noise ratio. Although the utility of this method is demonstrated for MRI, it can be adapted for other medical imaging applications.

Quantitative thickness prediction of tectonically deformed coal using Extreme Learning Machine and Principal Component Analysis: a case study

NASA Astrophysics Data System (ADS)

Wang, Xin; Li, Yan; Chen, Tongjun; Yan, Qiuyan; Ma, Li

2017-04-01

The thickness of tectonically deformed coal (TDC) has positive correlation associations with gas outbursts. In order to predict the TDC thickness of coal beds, we propose a new quantitative predicting method using an extreme learning machine (ELM) algorithm, a principal component analysis (PCA) algorithm, and seismic attributes. At first, we build an ELM prediction model using the PCA attributes of a synthetic seismic section. The results suggest that the ELM model can produce a reliable and accurate prediction of the TDC thickness for synthetic data, preferring Sigmoid activation function and 20 hidden nodes. Then, we analyze the applicability of the ELM model on the thickness prediction of the TDC with real application data. Through the cross validation of near-well traces, the results suggest that the ELM model can produce a reliable and accurate prediction of the TDC. After that, we use 250 near-well traces from 10 wells to build an ELM predicting model and use the model to forecast the TDC thickness of the No. 15 coal in the study area using the PCA attributes as the inputs. Comparing the predicted results, it is noted that the trained ELM model with two selected PCA attributes yields better predication results than those from the other combinations of the attributes. Finally, the trained ELM model with real seismic data have a different number of hidden nodes (10) than the trained ELM model with synthetic seismic data. In summary, it is feasible to use an ELM model to predict the TDC thickness using the calculated PCA attributes as the inputs. However, the input attributes, the activation function and the number of hidden nodes in the ELM model should be selected and tested carefully based on individual application.

Clinical images. Primary non-Hodgkin's lymphoma of the sigmoid colon in a child.

PubMed

Zhang, Ke Ren; Jia, Hui Min

2009-01-01

Primary non-Hodgkin's lymphomas of the gastrointestinal tract are rare in children, and few of these lymphomas are located in the sigmoid colon. The preoperative diagnosis rate is low. Complete resection is indicated if it can be done safely. Combination chemotherapy after resection is indicated.

The dynamics of Alzheimer's disease biomarkers in the Alzheimer's Disease Neuroimaging Initiative cohort.

PubMed

Caroli, A; Frisoni, G B

2010-08-01

The aim of this study was to investigate the dynamics of four of the most validated biomarkers for Alzheimer's disease (AD), cerebro-spinal fluid (CSF) Abeta 1-42, tau, hippocampal volume, and FDG-PET, in patients at different stage of AD. Two hundred twenty-nine cognitively healthy subjects, 154 mild cognitive impairment (MCI) patients converted to AD, and 193 (95 early and 98 late) AD patients were selected from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. For each biomarker, individual values were Z-transformed and plotted against ADAS-cog scores, and sigmoid and linear fits were compared. For most biomarkers the sigmoid model fitted data significantly better than the linear model. Abeta 1-42 time course followed a steep curve, stabilizing early in the disease course. CSF tau and hippocampal volume changed later showing similar monotonous trends, reflecting disease progression. Hippocampal loss trend was steeper and occurred earlier in time in APOE epsilon4 carriers than in non-carriers. FDG-PET started changing early in time and likely followed a linear decline. In conclusion, this study provides the first evidence in favor of the dynamic biomarker model which has recently been proposed. 2010 Elsevier Inc. All rights reserved.

The Role of Oxygen in Avascular Tumor Growth

PubMed Central

Grimes, David Robert; Kannan, Pavitra; McIntyre, Alan; Kavanagh, Anthony; Siddiky, Abul; Wigfield, Simon; Harris, Adrian; Partridge, Mike

2016-01-01

The oxygen status of a tumor has significant clinical implications for treatment prognosis, with well-oxygenated subvolumes responding markedly better to radiotherapy than poorly supplied regions. Oxygen is essential for tumor growth, yet estimation of local oxygen distribution can be difficult to ascertain in situ, due to chaotic patterns of vasculature. It is possible to avoid this confounding influence by using avascular tumor models, such as tumor spheroids, a much better approximation of realistic tumor dynamics than monolayers, where oxygen supply can be described by diffusion alone. Similar to in situ tumours, spheroids exhibit an approximately sigmoidal growth curve, often approximated and fitted by logistic and Gompertzian sigmoid functions. These describe the basic rate of growth well, but do not offer an explicitly mechanistic explanation. This work examines the oxygen dynamics of spheroids and demonstrates that this growth can be derived mechanistically with cellular doubling time and oxygen consumption rate (OCR) being key parameters. The model is fitted to growth curves for a range of cell lines and derived values of OCR are validated using clinical measurement. Finally, we illustrate how changes in OCR due to gemcitabine treatment can be directly inferred using this model. PMID:27088720

Rare extraskeletal Ewing's sarcoma mimicking as adenocarcinoma of the sigmoid.

PubMed

Mertens, Michelle; Haenen, Filip W N; Siozopoulou, Vasiliki; Van Cleemput, Marc

2017-06-01

Extraskeletal Ewing's sarcoma (EES) is a rare finding in comparison with Ewing's sarcoma of bone and usually manifests in young patients. However, even in older patients, one must consider the diagnosis. In this case, we describe a 52-year-old woman diagnosed with EES, mimicking as adenocarcinoma of the sigmoid. The tumor was not visualized by a multi-slice spiral computed tomography of the abdomen and pelvis with intravenous contrast, and eventually the diagnosis was made by positive immunohistochemical staining for CD99 and by molecular testing for EWSR1 translocation. This combination of the patient's age and the localization of the tumor mimicking an adenocarcinoma of the sigmoid has never been described before.

Gonorrhoea of the sigmoid neovagina in a male-to-female transgender.

PubMed

van der Sluis, Wouter B; Bouman, Mark-Bram; Gijs, Luk; van Bodegraven, Adriaan A

2015-07-01

A 33-year-old male-to-female transgender consulted our outpatient clinic with perneovaginal bleeding during and following coitus. Four years before, she underwent a total laparoscopic sigmoid neovaginoplasty. Physical, histological and endoscopic examination revealed neither focus of active bleeding nor signs of active inflammation. A polymerase chain reaction test performed on a neovaginal swab showed gonococcal infection. Treatment consisted of 500 mg intramuscular ceftriaxone. Three weeks later, our patient reported resolution of symptoms, consistent with eradication of the infection demonstrated by a follow-up neovaginal swab polymerase chain reaction. To our knowledge, this is the first case report of gonococcal infection of the sigmoid neovagina. © The Author(s) 2014.

[One staged laparoscopic surgery of colon cancer with liver metastasis in the Guillermo Almenara Hospital, Lima, Peru].

PubMed

Núñez Ju, Juan José; Coronado3, Cesar Carlos; Anchante Castillo, Eduardo; Sandoval Jauregui, Javier; Arenas Gamio, José

2016-01-01

We report a patient who was diagnosed sigmoid colon cancer associated with liver metastases in segment III. The patient underwent laparoscopic surgery where the sigmoid colon resection and hepatic metastasectomy were performed in a “one staged” surgical procedure. The pathological results showed moderately differentiated tubular adenocarcinoma in sigmoid colon, tubular adenocarcinoma metastases also in liver. Oncological surgical results were obtained with free edges of neoplasia, R0 Surgery, T3N0M1. After the optimal surgical results, the patient is handled by oncology for adjuvant treatment. We report here the sequence of events and a review of the literature.

Onset of the Magnetic Explosion in Solar Flames and Coronal Mass Ejections

NASA Technical Reports Server (NTRS)

Moore, Ronald L.; Sterling, Alphonse C.; Hudson, Hugh S.; Lemen, James R.

2001-01-01

We present observations of the magnetic field configuration and its transformation in six solar eruptive events that show good agreement with the standard bipolar model for eruptive flares. The observations are X-ray images from the Yohkoh soft X-ray telescope (SXT) and magnetograms from Kitt Peak National Solar Observatory, interpreted together with the 1-8 Angstrom X-ray flux observed by Geostationary Operational Environmental Satellites (GOES). The observations yield the following interpretations: (1) Each event is a magnetic explosion that occurs in an initially closed single bipole in which the core field is sheared and twisted in the shape of a sigmoid, having an oppositely curved elbow on each end. The arms of the opposite elbows are sheared past each other so that they overlap and are crossed low above the neutral line in the middle of the bipole. The elbows and arms seen in the SXT images are illuminated strands of the sigmoidal core field, which is a continuum of sheared/twisted field that fills these strands as well as the space between and around them; (2) Although four of the explosions are ejective (appearing to blow open the bipole) and two are confined (appearing to be arrested within the closed bipole), all six begin the same way. In the SXT images, the explosion begins with brightening and expansion of the two elbows together with the appearance of short bright sheared loops low over the neutral line under the crossed arms and, rising up from the crossed arms, long strands connecting the far ends of the elbows; and (3) All six events are single-bipole events in that during the onset and early development of the explosion they show no evidence for reconnection between the exploding bipole and any surrounding magnetic fields. We conclude that in each of our events the magnetic explosion was unleashed by runaway tether-cutting via implosive/explosive reconnection in the middle of the sigmoid, as in the standard model. The similarity of the onsets of the two confined explosions to the onsets of the four ejective explosions and their agreement with the model indicate that runaway reconnection inside a sheared core field can begin whether or not a separate system of overlying fields, or the structure of the bipole itself, allows the explosion to be ejective. Because this internal reconnection apparently begins at the very start of the sigmoid eruption and grows in step with the explosion, we infer that this reconnection is essential for the onset and growth of the magnetic explosion in eruptive flares and coronal mass ejections.

Introducing time delay in the evolution of new technology: the case study of nanotechnology

NASA Astrophysics Data System (ADS)

Georgalis, Evangelos E.; Aifantis, Elias C.

2013-12-01

Starting with Feynman's "There's Plenty of Room at the Bottom" prophetic lecture at Caltech in the 1960s, the term "nanotechnology" was first coined in the scientific literature in the 1980s. This was followed by the unprecedented growth in the corresponding scientific field in 2000 due to the financial incentive provided by President Clinton in the US, followed up by similar efforts in Europe, Japan, China and Russia. Today, nanotechnology has become a driving force for economic development, with applications in all fields of engineering, information technology, transport and energy, as well as biology and medicine. Thus, it is important to forecast its future growth and evolution on the basis of two different criteria: (1) the government and private capital invested in related activities, and (2) the number of scientific publications and popular articles dedicated to this field. This article aims to extract forecasts on the evolution of nanotechnology, using the standard logistic equation that result in familiar sigmoid curves, as well as to explore the effect of time delay on its evolution. Time delay is commonly known from previous biological and ecological models, in which time lag is either already known or can be experimentally measured. In contrast, in the case of a new technology, we must first define the method for determining time delay and then interpret its existence and role. Then we describe the implications that time delay may have on the stability of the sigmoidal behavior of nanotechnology evolution and on the related oscillations that may appear.

Using Commercial-Off-The-Shelf Speech Recognition Software for Conning U.S. Warships

DTIC Science & Technology

2003-06-01

Linear Regression , 2nd Edition, (John Wiley & Sons, St. Paul, Minnesota, 1985), pp. 267-269. 44 Current Projects About the Sigmoid Curve, Sigmoid Curve...Disabilities Conference, Conference Proceedings, [www.csun.edu/cod/conf/1998/proceedings/csun98_052.htm], as of June 2, 2003. 43 Weisberg, S., Applied

Sigmoid Volvulus Through a Transmesenteric Hernia.

PubMed

Brandão, Pedro Nuno; Martins, Vilma; Silva, Cristina; Davide, José

2017-06-01

Internal hernias are a rare pathology with very low incidence. Transmesenteric hernias represent less than 10% of all cases and may occur at any age. They involve more often the small bowel and, more rarely, the colon. We present a case of a sigmoid volvulus through a transmesenteric hernia in a 19-year-old patient.

Dedifferentiated liposarcoma arising from the sigmoid mesocolon: A case report

PubMed Central

Winn, Brody; Gao, John; Akbari, Homayoon; Bhattacharya, Baishali

2007-01-01

Dedifferentiated liposarcoma is a variant of liposarcoma with a more aggressive course. It occurs most commonly in the retroperitoneum and rarely in other anatomic locations. In the present report, we describe a case of dedifferentiated liposarcoma that occurred in an unusual location, sigmoid mesocolon, which has not yet been documented. PMID:17696239

Origin of sigmoid diameter distributions

Treesearch

William B. Leak

2002-01-01

Diameter distributions--numbers of trees over diameter at breast height (d.b.h.)--were simulated over 20-years using six diameter-growth schedules, six mortality trends, and three initial conditions. The purpose was to determine factors responsible for the short-term development of the arithmetic rotated sigmoid form of diameter distribution characterized by a plateau...

Simultaneous development of ulcerative colitis in the colon and sigmoid neovagina.

PubMed

Webster, Toni; Appelbaum, Heather; Weinstein, Toba A; Rosen, Nelson; Mitchell, Ian; Levine, Jeremiah J

2013-03-01

Vaginoplasty using sigmoid colon is a common technique for creation of a neovagina. However, special consideration must be given to potential long term consequences of using a colonic conduit for vaginal replacement. We report on the youngest described case in which a patient developed ulcerative colitis refractory to medical therapy with simultaneous involvement of a sigmoid neovagina requiring total proctocolectomy and neovaginectomy. A 17 year old XY female with a history of gonadal dysgenesis and sigmoid graft vaginoplasty presented with a history of bloody, mucoid vaginal discharge, abdominal pain, bloody diarrhea and weight loss. Colonic and neovaginal biopsies demonstrated active colitis with diffuse ulcerations, consistent with ulcerative colitis. Despite aggressive immunosuppressive treatment she had persistent neovaginal and colonic bleeding requiring multiple transfusions, subtotal colectomy and ultimately completion proctectomy and neovaginectomy. It is imperative to recognize that colectomy alone may be an inadequate surgical intervention in patients with ulcerative colitis and a colonic neovaginal graft and that a concomitant neovaginectomy may be integral in providing appropriate treatment. Copyright © 2013 Elsevier Inc. All rights reserved.

Commissioning of a grid-based Boltzmann solver for cervical cancer brachytherapy treatment planning with shielded colpostats.

PubMed

Mikell, Justin K; Klopp, Ann H; Price, Michael; Mourtada, Firas

2013-01-01

We sought to commission a gynecologic shielded colpostat analytic model provided from a treatment planning system (TPS) library. We have reported retrospectively the dosimetric impact of this applicator model in a cohort of patients. A commercial TPS with a grid-based Boltzmann solver (GBBS) was commissioned for (192)Ir high-dose-rate (HDR) brachytherapy for cervical cancer with stainless steel-shielded colpostats. Verification of the colpostat analytic model was verified using a radiograph and vendor schematics. MCNPX v2.6 Monte Carlo simulations were performed to compare dose distributions around the applicator in water with the TPS GBBS dose predictions. Retrospectively, the dosimetric impact was assessed over 24 cervical cancer patients' HDR plans. Applicator (TPS ID #AL13122005) shield dimensions were within 0.4 mm of the independent shield dimensions verification. GBBS profiles in planes bisecting the cap around the applicator agreed with Monte Carlo simulations within 2% at most locations; differing screw representations resulted in differences of up to 9%. For the retrospective study, the GBBS doses differed from TG-43 as follows (mean value ± standard deviation [min, max]): International Commission on Radiation units [ICRU]rectum (-8.4 ± 2.5% [-14.1, -4.1%]), ICRUbladder (-7.2 ± 3.6% [-15.7, -2.1%]), D2cc-rectum (-6.2 ± 2.6% [-11.9, -0.8%]), D2cc-sigmoid (-5.6 ± 2.6% [-9.3, -2.0%]), and D2cc-bladder (-3.4 ± 1.9% [-7.2, -1.1%]). As brachytherapy TPSs implement advanced model-based dose calculations, the analytic applicator models stored in TPSs should be independently validated before clinical use. For this cohort, clinically meaningful differences (>5%) from TG-43 were observed. Accurate dosimetric modeling of shielded applicators may help to refine organ toxicity studies. Copyright © 2013 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Robot-assisted laparoscopic resection of clinical T4b tumours of distal sigmoid and rectum: initial results.

PubMed

Crolla, Rogier M P H; Tersteeg, Janneke J C; van der Schelling, George P; Wijsman, Jan H; Schreinemakers, Jennifer M J

2018-05-16

Radical resection by multivisceral resection of colorectal T4 tumours is important to reduce local recurrence and improve survival. Oncological safety of laparoscopic resection of T4 tumours is controversial. However, robot-assisted resections might have advantages, such as 3D view and greater range of motion of instruments. The aim of this study is to evaluate the initial results of robot-assisted resection of T4 rectal and distal sigmoid tumours. This is a cohort study of a prospectively kept database of all robot-assisted rectal and sigmoid resections between 2012 and 2017. Patients who underwent a multivisceral resection for tumours appearing as T4 cancer during surgery were included. Rectal and sigmoid resections are routinely performed with the DaVinci robot, unless an indication for intra-operative radiotherapy exists. 28 patients with suspected T4 rectal or sigmoid cancer were included. Most patients (78%) were treated with neoadjuvant chemoradiotherapy (n = 19), short course radiotherapy with long waiting interval (n = 2) or chemotherapy (n = 1). En bloc resection was performed with the complete or part of the invaded organ (prostate, vesicles, bladder, abdominal wall, presacral fascia, vagina, uterus, adnex). In 3 patients (11%), the procedure was converted to laparotomy. Twenty-four R0-resections were performed (86%) and four R1-resections (14%). Median length of surgery was 274 min (IQR 222-354). Median length of stay was 6 days (IQR 5-11). Twelve patients (43%) had postoperative complications: eight (29%) minor complications and four (14%) major complications. There was no postoperative mortality. Robot-assisted laparoscopy seems to be a feasible option for the resection of clinical T4 cancer of the distal sigmoid and rectum in selected cases. Radical resections can be achieved in the majority of cases. Therefore, T4 tumours should not be regarded as a strict contraindication for robot-assisted surgery.

[Study on gasless-laparoscopic vaginoplasty using sigmoid colon segment].

PubMed

Bu, Lan; Wang, Huan-ying; Zhang, Jun; Wang, Li-ying; Wu, Ji-xiang; Li, Bin

2013-07-01

To study the clinical effect of gasless-laparoscopic vaginoplasty using sigmoid colon segment. Clinical data of 119 cases undergoing laparoscopic or gasless-laparoscopic vaginoplasty using a vascularized pedicled sigmoid colon segment in Beijing Anzhen Hospital from January 2007 to December 2010 were reviewed retrospectively. Those patients were classified into 57 cases with laparoscopic sigmoid colon vaginoplasty and 62 cases with gasless-laparoscopic sigmoid colon vaginoplasty. The operation time, blood loss in operating, bowel movement after operation, postoperation hospital duration, side effect, and artificial vagina were compared between laparoscopic and gasless-laparoscopic group. The vaginoplasty were preformed successfully in 119 cases. The mean operation time of were (159 ± 18) min in laparoscopic group and (146 ± 17) min in gasless-laparoscopic group, respectively, which reached statistical difference (P < 0.01). The blood loss in operating were (83 ± 14) ml and (86 ± 13) ml, bowel movement after operation were (68 ± 8) hours and (68 ± 11) hours, and postoperation hospital duration were (11.1 ± 1.3) days and (11.4 ± 1.9) days respectively in laparoscopic group and gasless-laparoscopic group. No significant difference were found in the blood loss in operating, bowel movement after operation, and postoperation hospital duration between two groups (P > 0.05) .No intraoperative complication occurred. There were two cases with incomplete adhesive intestinal obstruction at 15-20 days postoperatively, which one was in laparoscopic group and one was in gas-less laparoscopic group. At 6-50 months of following up (median time 12 months), all artificial vaginas had a capacity of over two fingers in wideness and 12-15 cm in length. Vaginal discharges resembled a milky white water or mucus without odour. Eighty-five patients with sexual intercourse reported satisfactory feeling. One patients complained vaginal stenosis in laparoscopic group. Gasless-laparoscopic vaginoplasty using sigmoid colon segment is an alternative feasible and practical treatment.

Antioxidant capacity index based on gold nanoparticles formation. Application to extra virgin olive oil samples.

PubMed

Della Pelle, Flavio; Vilela, Diana; González, María Cristina; Lo Sterzo, Claudio; Compagnone, Darío; Del Carlo, Michele; Escarpa, Alberto

2015-07-01

A simple gold nanoparticles (AuNPs) based colorimetric assay for the antioxidant activity determination has been developed. The AuNP formation is mediated by extra virgin olive oil (EVOO's) endogenous polyphenols; the reaction is described by a sigmoidal curve. The ratio KAuNPs/Xc(50) (slope of the linear part of the sigmoid/concentration at half value of the absorbance) was found to be the optimal parameter to report the antioxidant capacity with respect to the single KAuNPs or Xc(50) values. The obtained data demonstrated that the compounds with ortho-diphenols functionality are most active in reducing gold (III) to gold (0). Thus, intermediate activity was found for gallic acid, while tyrosol (mono-phenols) had a significant lower activity than the others antioxidant compounds (at least one order of magnitude). In the analysis of olive oil samples, a significant correlation among classical methods used to determine antioxidant activity and the proposed parameter was found with R values in the 0.96-0.97 range. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sigmoid colon vaginoplasty in children.

PubMed

Ekinci, S; Karnak, I; Ciftci, A O; Senocak, M E; Tanyel, F C; Büyükpamukçu, N

2006-06-01

Vaginal construction is necessary for the patients with aplasia of Mullerian ducts, testicular feminisation and androgen insensitivity syndromes. Many methods of vaginal construction have been described. We report here the outcomes of six adolescent patients who underwent sigmoid colon vaginoplasty with special emphasis on the surgical technique and outcomes. Between 1990 and 2003, six patients underwent sigmoid vaginoplasty after a diagnosis of 5alpha-reductase deficiency (n = 3), testicular feminisation (n = 2) or vaginal atresia (n = 1). The mean age was 16 years (13 to 18). Wide spectrum antibiotics and whole-gut preparation were used in all cases. A 15-20 cm segment of sigmoid colon was pulled through the retrovesical tunnel. The proximal end was closed in two layers in patients with 5alpha-reductase deficiency and with testicular feminisation. A distal anastomosis was carried out to the opening made on the vaginal plate (5alpha-reductase deficiency) or on the tip of the shallow rudimentary vagina (testicular feminisation). The sigmoid segment was interposed between the blind end of the atretic vagina and the perineum in the patient with vaginal atresia. Patients were instructed to perform daily vaginal irrigation. The neovagina was examined and calibrated under anaesthesia. No routine vaginal dilatation was recommended. All but one patient had an uneventful postoperative period and were discharged within 7-8 days. All patients had an excellent cosmetic result with an appropriate vaginal length. One of the patients experienced late stenosis of the introitus which responded to dilatations. Mucus discharge was not a significant problem. The patient with vaginal atresia (Bardet-Biedl syndrome) experienced deep vein thrombosis, renal failure and sepsis, resulting in death. Sigmoid colon vaginoplasty is a special procedure which appears appropriate for the construction of a new vagina in children. A sigmoid colon neovagina meets all necessary criteria after a vaginoplasty. It provides an adequate diameter and length, and produces less scar tissue in the perineum. It is self-moistening, easily adaptable to the uterus, cervix and rudimentary atretic vaginal segments and does not require routine dilatation. Mild stenosis of the introitus can be treated by dilatations and revision can be easily performed in severely stenotic cases. On the other hand, the patient may face morbidity after laparotomy and other serious complications may occur due to accompanying diseases.

[Synchronous sigmoideum- and caecum volvulus].

PubMed

Berg, Anna Korsgaard; Perdawood, Sharaf Karim

2015-09-21

This case presents a synchronous sigmoid- and caecum volvulus in a 69-year old man with Parkinson's disease, hypertension and previous history of colonic volvulus. On admission the patient had abdominal pain, nausea, vomiting and constipation. The CT scan showed a sigmoid volvulus with a dilated caecum. The synchronous sigmoideum- and caecum volvulus was diagnosed intraoperatively. Total colectomy and ileostomy was performed.

The Sigmoid Curve as a Metaphor for Growth and Change

ERIC Educational Resources Information Center

Hipkins, Rosemary; Cowie, Bronwen

2016-01-01

This paper introduces sigmoid or s-curve as a metaphor for describing the dynamics of change. We first encountered the s-curve as a description of a possible growth trajectory whereby populations become established, begin to flourish and the numbers increase rapidly until they reach some limit. At this point, the growth rate slows rapidly then…

Efficient Digital Implementation of The Sigmoidal Function For Artificial Neural Network

NASA Astrophysics Data System (ADS)

Pratap, Rana; Subadra, M.

2011-10-01

An efficient piecewise linear approximation of a nonlinear function (PLAN) is proposed. This uses simulink environment design to perform a direct transformation from X to Y, where X is the input and Y is the approximated sigmoidal output. This PLAN is then used within the outputs of an artificial neural network to perform the nonlinear approximation. In This paper, is proposed a method to implement in FPGA (Field Programmable Gate Array) circuits different approximation of the sigmoid function.. The major benefit of the proposed method resides in the possibility to design neural networks by means of predefined block systems created in System Generator environment and the possibility to create a higher level design tools used to implement neural networks in logical circuits.

[A case of locally advanced sigmoid colon cancer curatively resected after neoadjuvant chemotherapy with FOLFIRI plus panitumumab].

PubMed

Horioka, Kohei; Kaku, Keizo; Jimi, Sei-ichirou; Oohata, Yoshihiro; Kamei, Takafumi

2013-03-01

A 72-year-old woman having abdominal pain and high fever was diagnosed with KRAS wild-type sigmoid colon cancer, invading the urinary bladder and uterus with a pelvic abscess. Considering the difficulty of curative resection, we first performed sigmoid colostomy and abscess drainage. Remarkable tumor regression was indicated by CT and colonoscopy after 1 course of FOLFIRI and 5 courses of FOLFIRI+panitumumab. Following an additional 2 courses of panitumumab, sigmoidectomy and partialcystectomy were performed. Six courses of FOLFIRI+panitumumab were administered postoperatively and no recurrence has been observed for 7 months. FOLFIRI+panitumumab may be an effective preoperative chemotherapy for patients with KRAS wild-type locally advanced colon cancer.

Perforation of a malignant ovarian tumor into the recto-sigmoid colon.

PubMed

Bats, Anne-Sophie; Rockall, Andrea G; Singh, Naveena; Reznek, Rodney H; Jeyarajah, Arjun

2010-10-01

Ovarian cancer often presents at an advanced stage, but tends to be an intra-peritoneal disease that respects peritoneal planes. Thus, colo-rectal perforation of the tumor is an extremely rare presentation. The surgical treatment of malignant colo-ovarian fistula should include complete cyto-reduction at the same time as the treatment of the fistula. However, prognosis remains poor, because of the advanced stage of neoplasia. We report the case of a patient with an ovarian malignant tumor perforating into the recto-sigmoid colon. CT scan was the cornerstone of the radiological diagnosis. We managed to perform a complete cyto-reduction, including an en-bloc resection of the uterus, the mass, adnexa and recto-sigmoid with removal of the associated pelvic abscess.

Tubular sigmoid duplication in an adult man: an interesting incidental finding.

PubMed

Asour, Amani; Kim, Hyun-Kyung; Arya, Shobhit; Hepworth, Clive

2017-11-12

A 61-year-old man attended an outpatient colorectal clinic for a chronic, non-specific abdominal pain, associated with rectal bleeding. He underwent a number of investigations including a CT pneumocolon, which revealed an incidental finding of 20 cm of additional sigmoid colon. This case is interesting because tubular sigmoid duplication is an extremely unusual condition, rarely diagnosed in adults; only a few cases have been reported of this condition in the adult population. Our team chose to treat this patient conservatively, in order to avoid putting the patient at risk of an unnecessary surgery. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Pushing the envelope: laparoscopy and primary anastomosis are technically feasible in stable patients with Hinchey IV perforated acute diverticulitis and gross faeculent peritonitis.

PubMed

Di Saverio, Salomone; Vennix, Sandra; Birindelli, Arianna; Weber, Dieter; Lombardi, Raffaele; Mandrioli, Matteo; Tarasconi, Antonio; Bemelman, Willem A

2016-12-01

Modern management of severe acute complicated diverticulitis continues to evolve towards more conservative and minimally invasive strategies. Although open sigmoid colectomy with end colostomy remains the most commonly used procedure for the treatment of perforated diverticulitis with purulent/faeculent peritonitis, recent major advances challenged this traditional approach, including the increasing attitude towards primary anastomosis as an alternative to end colostomy and use of laparoscopic approach for urgent colectomy. Provided an accurate patients selection, having the necessary haemodynamic stability, pneumoperitoneum is established with open Hasson technique and diagnostic laparoscopy is performed. If faeculent peritonitis (Hinchey IV perforated diverticulitis) is found, laparoscopy can be continued and a further three working ports are placed using bladeless trocars, as in traditional laparoscopic sigmoidectomy, with the addition of fourth trocar in left flank. The feacal matter is aspirated either with large-size suction devices or, in case of free solid stools, these can be removed with novel application of tight sealing endobags, which can be used for scooping the feacal content out and for its protected retrieval. After decontamination, a sigmoid colectomy is performed in the traditional laparoscopic fashion. The sigmoid is fully mobilised from the retroperitoneum, and mesocolon is divided up to the origin of left colic vessels. Whenever mesentery has extremely inflamed and thickened oedematous tissues, an endostapler with vascular load can be used to avoid vascular selective ligatures. Splenic flexure should be appropriately mobilised. The specimen is extracted through mini-Pfannenstiel incision with muscle splitting technique. Transanal colo-rectal anastomosis is fashioned. Air-leak test must be performed and drains placed where appropriate. The video shows operative technique for a single-stage, entirely laparoscopic, washout and sigmoid colectomy with primary colorectal anastomosis in a 35-year-old male patient with severe and diffuse free faeculent diverticular peritonitis (Hinchey IV). The patient was managed post-operatively according to enhanced recovery protocol and discharged home after 9 days, following an uneventful recovery. This case documents the technical feasibility of a minimally invasive single-stage procedure in a patient with Hinchey IV perforated diverticulitis with diffuse feacal peritonitis. The laparoscopic approach facilitated an effective decontamination of the peritoneal cavity, with a combination of large suction devices and aid of protected retrieval by closed endobags for effectively and completely laparoscopic removal of the solid feacal matter, offering clear advantages and excellent results even in such challenging cases. With necessary expertise, the sigmoid resection can be thereafter safely and entirely performed laparoscopically, the specimen extracted through mini-Pfannenstiel incision, and a laparoscopic intracorporeal transanal circular primary anastomosis performed.

A novel model incorporating two variability sources for describing motor evoked potentials

PubMed Central

Goetz, Stefan M.; Luber, Bruce; Lisanby, Sarah H.; Peterchev, Angel V.

2014-01-01

Objective Motor evoked potentials (MEPs) play a pivotal role in transcranial magnetic stimulation (TMS), e.g., for determining the motor threshold and probing cortical excitability. Sampled across the range of stimulation strengths, MEPs outline an input–output (IO) curve, which is often used to characterize the corticospinal tract. More detailed understanding of the signal generation and variability of MEPs would provide insight into the underlying physiology and aid correct statistical treatment of MEP data. Methods A novel regression model is tested using measured IO data of twelve subjects. The model splits MEP variability into two independent contributions, acting on both sides of a strong sigmoidal nonlinearity that represents neural recruitment. Traditional sigmoidal regression with a single variability source after the nonlinearity is used for comparison. Results The distribution of MEP amplitudes varied across different stimulation strengths, violating statistical assumptions in traditional regression models. In contrast to the conventional regression model, the dual variability source model better described the IO characteristics including phenomena such as changing distribution spread and skewness along the IO curve. Conclusions MEP variability is best described by two sources that most likely separate variability in the initial excitation process from effects occurring later on. The new model enables more accurate and sensitive estimation of the IO curve characteristics, enhancing its power as a detection tool, and may apply to other brain stimulation modalities. Furthermore, it extracts new information from the IO data concerning the neural variability—information that has previously been treated as noise. PMID:24794287

Phosphate Sink Containing Two-Component Signaling Systems as Tunable Threshold Devices

PubMed Central

Amin, Munia; Kothamachu, Varun B.; Feliu, Elisenda; Scharf, Birgit E.; Porter, Steven L.; Soyer, Orkun S.

2014-01-01

Synthetic biology aims to design de novo biological systems and reengineer existing ones. These efforts have mostly focused on transcriptional circuits, with reengineering of signaling circuits hampered by limited understanding of their systems dynamics and experimental challenges. Bacterial two-component signaling systems offer a rich diversity of sensory systems that are built around a core phosphotransfer reaction between histidine kinases and their output response regulator proteins, and thus are a good target for reengineering through synthetic biology. Here, we explore the signal-response relationship arising from a specific motif found in two-component signaling. In this motif, a single histidine kinase (HK) phosphotransfers reversibly to two separate output response regulator (RR) proteins. We show that, under the experimentally observed parameters from bacteria and yeast, this motif not only allows rapid signal termination, whereby one of the RRs acts as a phosphate sink towards the other RR (i.e. the output RR), but also implements a sigmoidal signal-response relationship. We identify two mathematical conditions on system parameters that are necessary for sigmoidal signal-response relationships and define key parameters that control threshold levels and sensitivity of the signal-response curve. We confirm these findings experimentally, by in vitro reconstitution of the one HK-two RR motif found in the Sinorhizobium meliloti chemotaxis pathway and measuring the resulting signal-response curve. We find that the level of sigmoidality in this system can be experimentally controlled by the presence of the sink RR, and also through an auxiliary protein that is shown to bind to the HK (yielding Hill coefficients of above 7). These findings show that the one HK-two RR motif allows bacteria and yeast to implement tunable switch-like signal processing and provides an ideal basis for developing threshold devices for synthetic biology applications. PMID:25357192

The Flare/CME Connection

NASA Technical Reports Server (NTRS)

Moore, Ron; Falconer, David; Sterling, Alphonse

2008-01-01

We present evidence supporting the view that, while many flares are produced by a confined magnetic explosion that does not produce a CME, every CME is produced by an ejective magnetic explosion that also produces a flare. The evidence is that the observed heliocentric angular width of the full-blown CME plasmoid in the outer corona (at 3 to 20 solar radii) is about that predicted by the standard model for CME production, from the amount of magnetic flux covered by the co-produced flare arcade. In the standard model, sheared and twisted sigmoidal field in the core of an initially closed magnetic arcade erupts. As it erupts, tether-cutting reconnection, starting between the legs of the erupting sigmoid and continuing between the merging stretched legs of the enveloping arcade, simultaneously produces a growing flare arcade and unleashes the erupting sigmoid and arcade to become the low-beta plasmoid (magnetic bubble) that becomes the CME. The flare arcade is the downward product of the reconnection and the CME plasmoid is the upward product. The unleashed, expanding CME plasmoid is propelled into the outer corona and solar wind by its own magnetic field pushing on the surrounding field in the inner and outer corona. This tether-cutting scenario predicts that the amount of magnetic flux in the full-blown CME plasmoid nearly equals that covered by the full-grown flare arcade. This equality predicts (1) the field strength in the flare region from the ratio of the angular width of the CME in the outer corona to angular width of the full-grown flare arcade, and (2) an upper bound on the angular width of the CME in the outer corona from the total magnetic flux in the active region from which the CME explodes. We show that these predictions are fulfilled by observed CMEs. This agreement validates the standard model. The model explains (1) why most CMEs have much greater angular widths than their co-produced flares, and (2) why the radial path of a CME in the outer corona can be laterally far offset from the co-produced flare.

Phenotypic variations in osmotic lysis of Sahel goat erythrocytes in non-ionic glucose media.

PubMed

Igbokwe, Nanacha Afifi; Igbokwe, Ikechukwu Onyebuchi

2016-03-01

Erythrocyte osmotic lysis in deionised glucose media is regulated by glucose influx, cation efflux, and changes in cell volume after water diffusion. Transmembrane fluxes may be affected by varied expression of glucose transporter protein and susceptibility of membrane proteins to glucose-induced glycosylation and oxidation in various physiologic states. Variations in haemolysis of Sahel goat erythrocytes after incubation in hyposmotic non-ionic glucose media, associated with sex, age, late pregnancy, and lactation, were investigated. The osmotic fragility curve in glucose media was sigmoidal with erythrocytes from goats in late pregnancy (PRE) or lactation (LAC) or from kid (KGT) or middle-aged (MGT) goats. Non-sigmoidal phenotype occurred in yearlings (YGT) and old (OGT) goats. The composite fragility phenotype for males and non-pregnant dry (NPD) females was non-sigmoidal. Erythrocytes with non-sigmoidal curves were more stable than those with sigmoidal curves because of inflectional shift of the curve to the left. Erythrocytes tended to be more fragile with male than female sex, KGT and MGT than YGT and OGT, and LAC and PRE than NPD. Thus, sex, age, pregnancy, and lactation affected the haemolytic pattern of goat erythrocytes in glucose media. The physiologic state of the goat affected the in vitro interaction of glucose with erythrocytes, causing variations in osmotic stability with variants of fragility phenotype. Variations in the effect of high extracellular glucose concentrations on the functions of membrane-associated glucose transporter, aquaporins, and the cation cotransporter were presumed to be relevant in regulating the physical properties of goat erythrocytes under osmotic stress.

Early learning effect of residents for laparoscopic sigmoid resection.

PubMed

Bosker, Robbert; Groen, Henk; Hoff, Christiaan; Totte, Eric; Ploeg, Rutger; Pierie, Jean-Pierre

2013-01-01

To evaluate the effect of learning the laparoscopic sigmoid resection procedure on resident surgeons; establish a minimum number of cases before a resident surgeon could be expected to achieve proficiency with the procedure; and examine if an analysis could be used to measure and support the clinical evaluation of the surgeon's competence with the procedure. Retrospective analysis of data which was prospective entered in the database. From 2003 to 2007 all patients who underwent a laparoscopic sigmoid resection carried out by senior residents, who completed the procedure as the primary surgeon proctored by an experienced surgeon, were included in the study. A cumulative sum control chart (CUSUM) analysis was used evaluate performance. The procedure was defined as a failure if major intra-operative complications occurred such as intra abdominal organ injury, bleeding, or anastomotic leakage; if an inadequate number of lymph nodes (<12 nodes) were removed; or if conversion to an open surgical procedure was required. Thirteen residents performed 169 laparoscopic sigmoid resections in the period evaluated. A significant majority of the resident surgeons were able to consistently perform the procedure without failure after 11 cases and determined to be competent. One resident was not determined to be competent and the CUSUM score supported these findings. We concluded that at least 11 cases are required for most residents to obtain necessary competence with the laparoscopic sigmoid resection procedure. Evaluation with the CUSUM analysis can be used to measure and support the clinical evaluation of the resident surgeon's competence with the procedure. Copyright © 2013 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Vaginal reconstruction with sigmoid colon in patients with congenital absence of vagina and menses retention: a report of treatment experience in 22 young women.

PubMed

Yang, Bin; Wang, Ning; Zhang, Shulan; Wang, Mingqian

2013-01-01

We evaluated the surgical feasibility, sexual satisfaction and complications of vaginal reconstruction with sigmoid colon in patients with congenital absence of vagina and menses retention. Retrospective analysis of surgical techniques and long-term postoperative follow-up was performed for 22 patients who underwent vaginal reconstruction with sigmoid colon at a single hospital between 1977 and 2011 to treat congenital absence of vagina with menses retention. All patients achieved satisfactory sexual function after marriage. No patients experienced enterospastic abdominal pain during sexual intercourse. The neovaginas accommodated two or more fingers and had depths >10 cm. The mucous membranes were soft and flexible, and secretions of the sigmoid mucosa provided adequate and acceptable lubrication. No patient required vaginal stents, and none developed vaginal stenosis or reported pain with vaginal expansion. Fifteen of the 22 patients underwent hysterectomies due to cervical agenesis; seven retained their uterus and had onset of normal menses postoperatively. Two patients became pregnant 1 year after marriage; one achieved 38-week gestation, underwent cesarean section due to premature rupture of membranes, and delivered a healthy boy. The other experienced natural incomplete abortion and underwent curettage at her local hospital. This study confirms that sigmoid colon vaginal reconstruction is a good choice for treating congenital absence of vagina and menses retention and results in the closest approximation to the physical function of a normal female vagina. Reproductive ability can be retained in many cases for patients with a well-developed uterus and cervix.

Rotated sigmoid structures in managed uneven-aged northern hardwood stands: a look at the Burr Type III distribution

Treesearch

Jeffrey H. Gove; Mark J. Ducey; William B. Leak; Lianjun Zhang

2008-01-01

Stand structures from a combined density manipulation and even- to uneven-aged conversion experiment on the Bartlett Experimental Forest (New Hampshire, USA) were examined 25 years after initial treatment for rotated sigmoidal diameter distributions. A comparison was made on these stands between two probability density functions for fitting these residual structures:...

Management of the colonic volvulus in 2016.

PubMed

Perrot, L; Fohlen, A; Alves, A; Lubrano, J

2016-06-01

Colonic volvulus is the third leading cause of colonic obstruction worldwide, occurring at two principal locations: the sigmoid colon and cecum. In Western countries, sigmoid volvulus preferentially affects elderly men whereas cecal volvulus affects younger women. Some risk factors, such as chronic constipation, high-fiber diet, frequent use of laxatives, personal past history of laparotomy and anatomic predispositions, are common to both locations. Clinical symptomatology is non-specific, including a combination of abdominal pain, gaseous distention, and bowel obstruction. Abdominopelvic computerized tomography is currently the gold standard examination, allowing positive diagnosis as well as detection of complications. Specific management depends on the location, patient comorbidities and colonic wall viability, but treatment is an emergency in every case. If clinical or radiological signs of gravity are present, emergency surgery is mandatory, but is associated with high morbidity and mortality rates. For sigmoid volvulus without criteria of gravity, the ideal strategy is an endoscopic detorsion procedure followed, within 2 to 5 days, by surgery that includes a sigmoid colectomy with primary anastomosis. Exclusively endoscopic therapy must be reserved for patients who are at excessive risk for surgical intervention. In cecal volvulus, endoscopy has no role and surgery is the rule. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

In vivo measurement of human skin absorption of topically applied substances by a photoacoustic technique.

PubMed

Gutiérrez-Juárez, G; Vargas-Luna, M; Córdova, T; Varela, J B; Bernal-Alvarado, J J; Sosa, M

2002-08-01

A photoacoustic technique is used for studying topically applied substance absorption in human skin. The proposed method utilizes a double-chamber PA cell. The absorption determination was obtained through the measurement of the thermal effusivity of the binary system substance-skin. The theoretical model assumes that the effective thermal effusivity of the binary system corresponds to that of a two-phase system. Experimental applications of the method employed different substances of topical application in different parts of the body of a volunteer. The method is demonstrated to be an easily used non-invasive technique for dermatology research. The relative concentrations as a function of time of substances such as ketoconazol and sunscreen were determined by fitting a sigmoidal function to the data, while an exponential function corresponds to the best fit for the set of data for nitrofurazona, vaseline and vaporub. The time constants associated with the rates of absorption, were found to vary in the range between 10 and 58 min, depending on the substance and the part of the body.

A Height–Diameter Curve for Longleaf Pine Plantations in the Gulf Coastal Plain

Treesearch

Daniel Leduc; Jeffery Goelz

2009-01-01

Tree height is a critical component of a complete growth-and-yield model because it is one of the primary components used in volume calculation. To develop an equation to predict total height from dbh for longleaf pine (Pinus palustris Mill.) plantations in the West Gulf region, many different sigmoidal curve forms, weighting functions, and ways of...

Characterization of Radar Signals Using Neural Networks

DTIC Science & Technology

1990-12-01

e***e*e*eeeeeeeeeeeesseeeeeese*eee*e*e************s /* Function Name: load.input.ptterns Number: 4.1 /* Description: This function determines wether ...XSE.last.layer Number: 8.5 */ /* Description: The function determines wether to backpropate the *f /* parameter by the sigmoidal or linear update...Sigmoidal Function," Mathematics of Control, Signals and Systems, 2:303-314 (March 1989). 6. Dayhoff, Judith E. Neural Network Architectures. New York: Van

Procedural key steps in laparoscopic colorectal surgery, consensus through Delphi methodology.

PubMed

Dijkstra, Frederieke A; Bosker, Robbert J I; Veeger, Nicolaas J G M; van Det, Marc J; Pierie, Jean Pierre E N

2015-09-01

While several procedural training curricula in laparoscopic colorectal surgery have been validated and published, none have focused on dividing surgical procedures into well-identified segments, which can be trained and assessed separately. This enables the surgeon and resident to focus on a specific segment, or combination of segments, of a procedure. Furthermore, it will provide a consistent and uniform method of training for residents rotating through different teaching hospitals. The goal of this study was to determine consensus on the key steps of laparoscopic right hemicolectomy and laparoscopic sigmoid colectomy among experts in our University Medical Center and affiliated hospitals. This will form the basis for the INVEST video-assisted side-by-side training curriculum. The Delphi method was used for determining consensus on key steps of both procedures. A list of 31 steps for laparoscopic right hemicolectomy and 37 steps for laparoscopic sigmoid colectomy was compiled from textbooks and national and international guidelines. In an online questionnaire, 22 experts in 12 hospitals within our teaching region were invited to rate all steps on a Likert scale on importance for the procedure. Consensus was reached in two rounds. Sixteen experts agreed to participate. Of these 16 experts, 14 (88%) completed the questionnaire for both procedures. Of the 14 who completed the first round, 13 (93%) completed the second round. Cronbach's alpha was 0.79 for the right hemicolectomy and 0.91 for the sigmoid colectomy, showing high internal consistency between the experts. For the right hemicolectomy, 25 key steps were established; for the sigmoid colectomy, 24 key steps were established. Expert consensus on the key steps for laparoscopic right hemicolectomy and laparoscopic sigmoid colectomy was reached. These key steps will form the basis for a video-assisted teaching curriculum.

Characterization and autoradiographic localization of neurotensin binding sites in human sigmoid colon.

PubMed

Azriel, Y; Burcher, E

2001-06-01

Radioiodinated neurotensin ((125)I-NT) was used to characterize and localize NT binding sites in normal human sigmoid colon. Specimens were obtained from patients (30-77 years old) undergoing resection for colon carcinoma. Specific binding of (125)I-NT to sigmoid circular muscle membranes was enhanced by o-phenanthroline (1 mM) but other peptidase inhibitors were ineffective. (125)I-NT bound to a high-affinity site of K(d) = 0.88 +/- 0.09 nM and B(max) = 4.03 +/- 0.66 fmol/mg of wet weight tissue (n = 14), although in the majority of patients another site, of low but variable affinity, could also be detected. Specific binding of 50 pM (125)I-NT was inhibited by NT(8-13) > NT > SR142948A > or = neuromedin N > or = SR48692, consistent with binding to the NT1 receptor. In autoradiographic studies, dense specific binding of (125)I-NT was seen over myenteric and submucosal ganglia, moderate binding over circular muscle, and sparse binding over longitudinal muscle and taenia coli. Levocabastine, which has affinity for the NT2 receptor, did not inhibit specific binding of (125)I-NT in membrane competition or autoradiographic studies. NT contracted sigmoid colon circular muscle strips with a pD(2) value of 6.8 +/- 0.2 nM (n = 25). The contractile responses to NT were significantly potentiated in the presence of tetrodotoxin (1 microM), indicating a neural component. Results from functional studies support actions for NT on both muscle and enteric neurons, consistent with the presence of NT receptors on circular muscle and ganglia of human sigmoid colon. The lack of inhibition by levocabastine suggests that the second binding site detected does not correspond to the NT2 receptor.

Difference in real-time magnetic image analysis of colonic looping patterns between males and females undergoing diagnostic colonoscopy.

PubMed

Lam, Jacob; Wilkinson, James; Brassett, Cecilia; Brown, Jonathan

2018-05-01

Background and study aim  Magnetic imaging technology is of proven benefit to trainees in colonoscopy, but few studies have examined its benefits in experienced hands. There is evidence that colonoscopy is more difficult in women. We set out to investigate (i) associations between the looping configurations in the proximal and distal colon and (ii) differences in the looping prevalence between the sexes. We have examined their significance in terms of segmental intubation times and position changes required for the completion of colonoscopy. Patients and methods  We analyzed 103 consecutive synchronized luminal and magnetic image videos of diagnostic colonoscopies with normal anatomy undertaken by a single experienced operator. Results  Deep transverse loops and sigmoid N-loops were more common in females. A deep transverse loop was more likely to be present if a sigmoid alpha-loop or N-loop had formed previously. Patients with sigmoid N-loops were turned more frequently from left lateral to supine before the sigmoid-descending junction was reached, but there was no statistical correlation between completion time and looping pattern. Conclusions  This study has reexamined the prevalence of the common looping patterns encountered during colonoscopy and has identified differences between the sexes. This finding may offer an explanation as to why colonoscopy has been shown to be more difficult in females. Although a deep transverse loop following a resolved sigmoid alpha-loop was the most commonly encountered pattern, no statistical correlation between completion time and looping pattern could be shown. It is the first study to examine segmental completion times using a magnetic imager in expert hands.

Grave's disease with transverse and sigmoid sinus thrombosis needing surgical intervention.

PubMed

Srikant, Banumathy; Balasubramaniam, Srikant

2013-07-01

Thrombosis of venous sinuses associated with thyrotoxicosis is rare, and isolated transverse and sigmoid sinus thrombosis is rarer and reported only once previously. We present a case of Graves disease, who suffered unilateral sigmoid and transverse sinus thrombosis with intracranial hemorrhage. A 42-year-old female, a diagnosed case of Graves disease, presented to us with headache, drowsiness, and hemiparesis. Computed Tomography revealed a large right temporo-parieto-occipital venous infarct. The patient needed surgical intervention in the form of decompressive craniotomy following which she improved, and on follow-up is having no deficits. Thrombophilia profile showed a low Protein S and Anti thrombin III (AT III) levels. Deranged thrombophilia profile in combination with the hypercoagulable state in thyrotoxicosis, most likely precipitated the thrombotic event. Timely surgical intervention can be offered in selective cases with a good clinical outcome.

Infrared small target enhancement: grey level mapping based on improved sigmoid transformation and saliency histogram

NASA Astrophysics Data System (ADS)

Wan, Minjie; Gu, Guohua; Qian, Weixian; Ren, Kan; Chen, Qian

2018-06-01

Infrared (IR) small target enhancement plays a significant role in modern infrared search and track (IRST) systems and is the basic technique of target detection and tracking. In this paper, a coarse-to-fine grey level mapping method using improved sigmoid transformation and saliency histogram is designed to enhance IR small targets under different backgrounds. For the stage of rough enhancement, the intensity histogram is modified via an improved sigmoid function so as to narrow the regular intensity range of background as much as possible. For the part of further enhancement, a linear transformation is accomplished based on a saliency histogram constructed by averaging the cumulative saliency values provided by a saliency map. Compared with other typical methods, the presented method can achieve both better visual performances and quantitative evaluations.

Trans-anal barotrauma by compressed air leading to sigmoid perforation due to a dangerous practical joke

PubMed Central

Pahwa, Harvinder Singh; Kumar, Awanish; Srivastava, Rohit; Rai, Anurag

2012-01-01

To present a case report of trans-anal barotrauma by high-pressure compressed air jet as a dangerous practical joke, that is, playful insufflation of high-pressure air jet through the anal orifice resulting in sigmoid perforation. The patient presented to emergency a day later with complaints of severe pain in the abdomen and abdominal distension following insufflation of high-pressure air jet through the anus. On examination, he had signs suggestive of perforation peritonitis and x-ray of the abdomen showed gas under the diaphragm. An emergency exploratory laparotomy was performed which revealed a 4-cm perforation in the sigmoid colon. Resection of the segment containing perforation along with the surrounding devitalised part was done with double-barrel colostomy. Reversal of colostomy was done after 8 weeks. Follow-up was uneventful. PMID:22854240

Trans-anal barotrauma by compressed air leading to sigmoid perforation due to a dangerous practical joke.

PubMed

Pahwa, Harvinder Singh; Kumar, Awanish; Srivastava, Rohit; Rai, Anurag

2012-08-01

To present a case report of trans-anal barotrauma by high-pressure compressed air jet as a dangerous practical joke, that is, playful insufflation of high-pressure air jet through the anal orifice resulting in sigmoid perforation. The patient presented to emergency a day later with complaints of severe pain in the abdomen and abdominal distension following insufflation of high-pressure air jet through the anus. On examination, he had signs suggestive of perforation peritonitis and x-ray of the abdomen showed gas under the diaphragm. An emergency exploratory laparotomy was performed which revealed a 4-cm perforation in the sigmoid colon. Resection of the segment containing perforation along with the surrounding devitalised part was done with double-barrel colostomy. Reversal of colostomy was done after 8 weeks. Follow-up was uneventful.

Extreme-ultraviolet observations of global coronal wave rotation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Attrill, G. D. R.; Long, D. M.; Green, L. M.

2014-11-20

We present evidence of global coronal wave rotation in EUV data from SOHO/EIT, STEREO/EUVI, and SDO/AIA. The sense of rotation is found to be consistent with the helicity of the source region (clockwise for positive helicity, anticlockwise for negative helicity), with the source regions hosting sigmoidal structures. We also study two coronal wave events observed by SDO/AIA where no clear rotation (or sigmoid) is observed. The selected events show supporting evidence that they all originate with flux rope eruptions. We make comparisons across this set of observations (both with and without clear sigmoidal structures). On examining the magnetic configuration ofmore » the source regions, we find that the nonrotation events possess a quadrupolar magnetic configuration. The coronal waves that do show a rotation originate from bipolar source regions.« less

[A Case of Uterine Body Metastasis from Sigmoid Colon Adenocarcinoma].

PubMed

Mayumi, Katsuyuki; Terakura, Masanobu; Hori, Takaaki; Takemura, Masashi

2017-11-01

We report a case of metastatic carcinoma to the uterine body from a colorectal adenocarcinoma. A 73-year-old woman underwent laparoscopic sigmoidectomy for sigmoid colon carcinoma 2 years before. In the following study, her serum carcinoembryonic antigen level was elevated, and a uterine body tumor invading the rectal wall was detected via enhanced computed tomography. Colonoscopic examination revealed an elevated lesion at the rectum, which was diagnosed as an adenocarcinoma. Based on these results, we diagnosed the uterine tumor as metastatic tumor from the colon carcinoma. Immunostaining was negative for CK7, but positive for CK20. Thus, we confirmed metastasis of the sigmoid colon cancer to the uterus. Metastasis to the female genital tract from extragenital malignancies are rare, and the prognosis is extremely poor. However, some patients attain long-term survival by surgical intervention even in such cases.

Atmospheric pressure plasma jet for biomedical applications characterised by passive thermal probe

NASA Astrophysics Data System (ADS)

Mance, Diana; Wiese, Ruben; Kewitz, Thorben; Kersten, Holger

2018-05-01

Atmospheric pressure plasma jets (APPJs) are a promising tool in medicine with extensive possibilities of utilization. For a safe and therapeutically effective application of APPJs, it is necessary to know in detail the physical processes in plasma as well as possible hazards. In this paper, we focus on plasma thermal energy transferred to the substrate, i.e. to a passive thermal probe acting as substrate dummy. Specifically, we examined the dependence of transferred energy on the distance from the plasma source outlet, on the gas flow rate, and on the length of the visible plasma plume. The plasma plume is the plasma carried by the gas flow from the outlet of the source into the ambient air. The results show the distance between the plasma-generating device and the substrate to be the most important determinant of the transferred thermal energy, among the three examined variables. Most importantly for the end-user, the results also show this relation to be non-linear. To describe this relation, we chose a model based on a Boltzmann type of sigmoid function. Based on the results of our modelling and visual inspection of the plasma, we provide sort of a user guide for the adjustment of a suitable energy flux on the (bio) substrate.

Simultaneous Primary Hodgkin's Lymphoma of the Sigmoid Colon and Papillary Thyroid Carcinoma in an HIV-Positive Patient.

PubMed

Liszewski, Walter; Sittig, Mark; Kandil, Emad; Van Sickels, Nicholas; Safah, Hana

2015-01-01

Primary Hodgkin's lymphoma of the colon is a rare phenomenon previously only reported in patients with chronic diverticulitis or inflammatory bowel disease. Herein we report a case of primary Hodgkin's lymphoma of the sigmoid colon in an HIV-positive patient without a history of inflammatory bowel disease or chronic diverticulitis that was later complicated by the discovery of concurrent papillary thyroid carcinoma.

Pyrene absorption can be a convenient method for probing critical micellar concentration (cmc) and indexing micellar polarity.

PubMed

Basu Ray, Gargi; Chakraborty, Indranil; Moulik, Satya P

2006-02-01

The critical micellar concentration (cmc) of both ionic and non-ionic surfactants can be conveniently determined from the measurements of UV absorption of pyrene in surfactant solution. The results on a number of surfactants have agreed with that realized from pyrene fluorescence measurements as well as that obtained following conductometric, tensiometric and calorimetric methods. The absorbance vs [surfactant] profiles for all the major UV spectral peaks of pyrene have been found to be sigmoidal in nature which were analyzed according to Sigmoidal-Boltzmann equation (SBE) to evaluate the cmcs of the studied surfactants. The difference between the initial and the final asymptotes (a(i) and a(f), respectively) of the sigmoidal profile, Delta a = (a(f)-a(i)) and the slope of the sigmoid, S(sig) have been observed to depend on the type of the surfactant. The Delta a has shown a linear correlation with the ratio of the fluorescence intensities of the first and the third vibronic peaks, I1/I3 of pyrene which is considered as a measure of the environmental polarity (herein micellar interior) of the probe (pyrene). Thus, Delta a values have the prospect for use as another index for the estimation of polarity of micellar interior.

Clinical characteristics of pulsatile tinnitus caused by sigmoid sinus diverticulum and wall dehiscence: a study of 54 patients.

PubMed

Wang, Guo-Peng; Zeng, Rong; Liu, Zhao-Hui; Liang, Xi-Hong; Xian, Jun-Fang; Wang, Zhen-Chang; Gong, Shu-Sheng

2014-01-01

CT angiography (CTA) and digital subtraction angiography (DSA) are valuable tools in imaging work-ups for the diagnosis of sigmoid sinus diverticulum (SSD) and sigmoid sinus wall dehiscence (SSWD). The development of pulsatile tinnitus (PT) resulting from SSD and SSWD may be associated with the dominance of venous systems. Our goal was to evaluate the clinical characteristics of PT caused by SSD and SSWD. This was a retrospective chart review undertaken in a tertiary academic referral center. Fifty-four patients with PT due to SSD and SSWD were recruited. Hospital files of these patients were assessed. Data included medical history, physical examinations, auxiliary examinations, and radiographic findings of CTA and DSA. The study population comprised 51 females and 3 males. Most patients with PT caused by SSD and SSWD were middle-aged women. All had normal otoscopy results. Anomalies occurred in or adjacent to the region of the transverse-sigmoid sinus junction in 52 patients. Half of the patients (27/54) presented abnormal results of examination of blood lipids. There were 57.41% (31/54) cases with ipsilateral dominance of the venous system, 9.26% (5/54) cases with contralateral dominance, and 33.33% (18/54) cases with co-dominance of the venous system.

[Surgical treatment of colonic volvulus. 10-year experience at the Instituto Nacional de la Nutrición Salvador Zubirán].

PubMed

Remes-Troche, J M; Pérez-Martínez, C; Rembis, V; Arch Ferrer, J; Ayala González, M; Takahashi, T

1997-01-01

To analyze morbidity-mortality and results of surgical treatment for colonic volvulus. Retrospective review of 33 patients who underwent surgical treatment for colonic volvulus from 1986 through 1996. Mean age was 62 +/- 20 years (SD) with predominance of female sex (2:1). There were 25 cases of sigmoid volvulus (76%), 7 in the cecum (21%) and 1 in the transverse colon (3%). Colonic necrosis and/or perforation were most frequently seen in the right and transverse colon (50%) than in the sigmoid (4%) (P < 0.002). Operative morbidity was 45% with mortality of 21%. Age was the only variable statistically significant for operative morbidity (52 +/- 23 years in patients without morbidity vs 71 +/- 17 years in patients with morbidity, P = 0.02). Surgical procedures for sigmoid volvulus were resection in 13 and fixation in 12. Recurrence after fixation was 38% to 12 months and 69% to 24 months (Kaplan-Meier), with associated mortality of 50%. There was no recurrence after resections. Treatment for cecal volvulus was cecopexy in 4 cases, with one recurrence; and right hemicolectomy without recurrence. The results should encourage resective procedures in sigmoid volvulus because the risk of recurrence after fixation is high and the morbidity-mortality is similar. Elderly patients are more susceptible to complications.

Using Large-Scale Precipitation to Validate AMSR-E Satellite Soil Moisture Estimates by Means of Mutual Information

NASA Astrophysics Data System (ADS)

Tuttle, S. E.; Salvucci, G.

2013-12-01

Validation of remotely sensed soil moisture is complicated by the difference in scale between remote sensing footprints and traditional ground-based soil moisture measurements. To address this issue, a new method was developed to evaluate the useful information content of remotely sensed soil moisture data using only large-scale precipitation (i.e. without modeling). Under statistically stationary conditions [Salvucci, 2001], precipitation conditionally averaged according to soil moisture (denoted E[P|S]) results in a sigmoidal shape in a manner that reflects the dependence of drainage, runoff, and evapotranspiration on soil moisture. However, errors in satellite measurement and algorithmic conversion of satellite data to soil moisture can degrade this relationship. Thus, remotely sensed soil moisture products can be assessed by the degree to which the natural sigmoidal relationship is preserved. The metric of mutual information was used as an error-dependent measure of the strength of the sigmoidal relationship, calculated from a two-dimensional histogram of soil moisture versus precipitation estimated using Gaussian mixture models. Three AMSR-E algorithms (VUA-NASA [Owe et al., 2001], NASA [Njoku et al., 2003], and U. Montana [Jones & Kimball, 2010]) were evaluated with the method for a nine-year period (2002-2011) over the contiguous United States at ¼° latitude-longitude resolution, using precipitation from the North American Land Data Assimilation System (NLDAS). The U. Montana product resulted in the highest mutual information for 57% of the region, followed by VUA-NASA and NASA at 40% and 3%, respectively. Areas where the U. Montana product yielded the maximum mutual information generally coincided with low vegetation biomass and flatter terrain, while the VUA-NASA product contained more useful information in more rugged and highly vegetated areas. Additionally, E[P|S] curves resulting from the Gaussian mixture method can potentially be decomposed into their conditional evapotranspiration and drainage plus runoff components using matrix factorization methods, allowing for time-averaged mapping of these fluxes over the study area.

Response-time enhancement of a clinical gas analyzer facilitates measurement of breath-by-breath gas exchange.

PubMed

Farmery, A D; Hahn, C E

2000-08-01

Tidal ventilation gas-exchange models in respiratory physiology and medicine not only require solution of mass balance equations breath-by-breath but also may require within-breath measurements, which are instantaneous functions of time. This demands a degree of temporal resolution and fidelity of integration of gas flow and concentration signals that cannot be provided by most clinical gas analyzers because of their slow response times. We have characterized the step responses of the Datex Ultima (Datex Instrumentation, Helsinki, Finland) gas analyzer to oxygen, carbon dioxide, and nitrous oxide in terms of a Gompertz four-parameter sigmoidal function. By inversion of this function, we were able to reduce the rise times for all these gases almost fivefold, and, by its application to real on-line respiratory gas signals, it is possible to achieve a performance comparable to the fastest mass spectrometers. With the use of this technique, measurements required for non-steady-state and tidal gas-exchange models can be made easily and reliably in the clinical setting.

Measurement of the volume growth rate of single budding yeast with the MOSFET-based microfluidic Coulter counter

PubMed Central

Sun, Jiashu; Stowers, Chris C.; Boczko, Erik M.

2012-01-01

We report on measurements of the volume growth rate of ten individual budding yeast cells using a recently developed MOSFET-based microfluidic Coulter counter. The MOSFET-based microfluidic Coulter counter is very sensitive, provides signals that are immune from the baseline drift, and can work with cell culture media of complex composition. These desirable features allow us to directly measure the volume growth rate of single cells of Saccharomyces cerevisiae LYH3865 strain budding yeast in YNB culture media over a whole cell cycle. Results indicate that all budding yeast follow a sigmoid volume growth profile with reduced growth rates at the initial stage before the bud emerges and the final stage after the daughter gets mature. Analysis of the data indicates that even though all piecewise linear, Gomperitz, and Hill’s function models can fit the global growth profile equally well, the data strongly support local exponential growth phenomenon. Accurate volume growth measurements are important for applications in systems biology where quantitative parameters are required for modeling and simulation. PMID:20717618

Measurement of the volume growth rate of single budding yeast with the MOSFET-based microfluidic Coulter counter.

PubMed

Sun, Jiashu; Stowers, Chris C; Boczko, Erik M; Li, Deyu

2010-11-07

We report on measurements of the volume growth rate of ten individual budding yeast cells using a recently developed MOSFET-based microfluidic Coulter counter. The MOSFET-based microfluidic Coulter counter is very sensitive, provides signals that are immune from the baseline drift, and can work with cell culture media of complex composition. These desirable features allow us to directly measure the volume growth rate of single cells of Saccharomyces cerevisiae LYH3865 strain budding yeast in YNB culture media over a whole cell cycle. Results indicate that all budding yeast follow a sigmoid volume growth profile with reduced growth rates at the initial stage before the bud emerges and the final stage after the daughter gets mature. Analysis of the data indicates that even though all piecewise linear, Gomperitz, and Hill's function models can fit the global growth profile equally well, the data strongly support local exponential growth phenomenon. Accurate volume growth measurements are important for applications in systems biology where quantitative parameters are required for modeling and simulation.

An assessment of colostomy irrigation.

PubMed

Laucks, S S; Mazier, W P; Milsom, J W; Buffin, S E; Anderson, J M; Warwick, M K; Surrell, J A

1988-04-01

One hundred patients with permanent sigmoid colostomies were surveyed to determine their satisfaction and success with the "irrigation" technique of colostomy management. Most patients who irrigate their colostomies achieve continence. Odors and skin irritation are minimized. The irrigation method is economical, time efficient, and allows a reasonably liberal diet. It avoids bulky appliances and is safe. In appropriately selected patients, the irrigation technique is the method of choice for management of an end-sigmoid colostomy.

Wandering spleen, gastric and pancreatic volvulus and right-sided descending and sigmoid colon.

PubMed

Flores-Ríos, Enrique; Méndez-Díaz, Cristina; Rodríguez-García, Esther; Pérez-Ramos, Tania

2015-10-01

Wandering spleen is a rare condition, characterized by a mobile spleen that is attached only by an elongated vascular pedicle, allowing it to migrate to any part of the abdomen or pelvis. Mesenteroaxial gastric volvulus usually occurs in children and may be associated with wandering spleen. Both entities result from abnormal laxity or absence of the peritoneal attachments due to abnormal fusion of the peritoneal mesenteries. Pancreatic volvulus is a very rare anomaly, with only a few isolated case reports described in association with wandering spleen. Anomalous right sided descending and sigmoid colon is a very rare entity and its association with wandering spleen has not been previously reported. We report a case of wandering spleen associated with mesenteroaxial gastric volvulus, pancreatic volvulus and rightward shift of the splenic flexure of the colon and right sided descending and sigmoid colon in a young female.

Wandering spleen, gastric and pancreatic volvulus and right-sided descending and sigmoid colon

PubMed Central

Flores-Ríos, Enrique; Méndez-Díaz, Cristina; Rodríguez-García, Esther; Pérez-Ramos, Tania

2015-01-01

Wandering spleen is a rare condition, characterized by a mobile spleen that is attached only by an elongated vascular pedicle, allowing it to migrate to any part of the abdomen or pelvis. Mesenteroaxial gastric volvulus usually occurs in children and may be associated with wandering spleen. Both entities result from abnormal laxity or absence of the peritoneal attachments due to abnormal fusion of the peritoneal mesenteries. Pancreatic volvulus is a very rare anomaly, with only a few isolated case reports described in association with wandering spleen. Anomalous right sided descending and sigmoid colon is a very rare entity and its association with wandering spleen has not been previously reported. We report a case of wandering spleen associated with mesenteroaxial gastric volvulus, pancreatic volvulus and rightward shift of the splenic flexure of the colon and right sided descending and sigmoid colon in a young female. PMID:26629290

A Novel Extreme Learning Machine Classification Model for e-Nose Application Based on the Multiple Kernel Approach.

PubMed

Jian, Yulin; Huang, Daoyu; Yan, Jia; Lu, Kun; Huang, Ying; Wen, Tailai; Zeng, Tanyue; Zhong, Shijie; Xie, Qilong

2017-06-19

A novel classification model, named the quantum-behaved particle swarm optimization (QPSO)-based weighted multiple kernel extreme learning machine (QWMK-ELM), is proposed in this paper. Experimental validation is carried out with two different electronic nose (e-nose) datasets. Being different from the existing multiple kernel extreme learning machine (MK-ELM) algorithms, the combination coefficients of base kernels are regarded as external parameters of single-hidden layer feedforward neural networks (SLFNs). The combination coefficients of base kernels, the model parameters of each base kernel, and the regularization parameter are optimized by QPSO simultaneously before implementing the kernel extreme learning machine (KELM) with the composite kernel function. Four types of common single kernel functions (Gaussian kernel, polynomial kernel, sigmoid kernel, and wavelet kernel) are utilized to constitute different composite kernel functions. Moreover, the method is also compared with other existing classification methods: extreme learning machine (ELM), kernel extreme learning machine (KELM), k-nearest neighbors (KNN), support vector machine (SVM), multi-layer perceptron (MLP), radical basis function neural network (RBFNN), and probabilistic neural network (PNN). The results have demonstrated that the proposed QWMK-ELM outperforms the aforementioned methods, not only in precision, but also in efficiency for gas classification.

TH-AB-BRA-04: Dosimetric Evaluation of MR-Guided HDR Brachytherapy Planning for Cervical Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamio, Y; Barkati, M; Beliveau-Nadeau, D

2016-06-15

Purpose: To perform a retrospective study on 16 patients that had both CT and T2-weighted MR scans done at first fraction using the Utrecht CT/MR applicator (Elekta Brachytherapy) in order to evaluate uncertainties associated with an MR-only planning workflow. Methods: MR-workflow uncertainties were classified in three categories: reconstruction, registration and contouring. A systematic comparison of the CT and MR contouring, manual reconstruction and optimization process was performed to evaluate the impact of these uncertainties on the recommended GEC ESTRO DVH parameters: D90% and V100% for HR-CTV as well as D2cc for bladder, rectum, sigmoid colon and small bowel. This comparisonmore » was done using the following four steps: 1. Catheter reconstruction done on MR images with original CT-plan contours and dwell times. 2. OAR contours adjusted on MR images with original CT-plan reconstruction and dwell times. 3. Both reconstruction and contours done on MR images with original CT-plan dwell times. 4. Entire MR-based workflow optimized dwell times reimported to the original CT-plan. Results: The MR-based reconstruction process showed average D2cc deviations of 4.5 ± 3.0%, 1.5 ± 2.0%, 2.5 ± 2.0% and 2.0 ± 1.0% for the bladder, rectum, sigmoid colon and small bowels respectively with a maximum of 10%, 6%, 6% and 4%. The HR-CTV’s D90% and V100% average deviations was found to be 4.0 ± 3.0%, and 2.0 ± 2.0% respectively with a maximum of 10% and 6%. Adjusting contours on MR-images was found to have a similar impact. Finally, the optimized MR-based workflow dwell times were found to still give acceptable plans when re-imported to the original CT-plan which validated the entire workflow. Conclusion: This work illustrates a systematic validation method for centers wanting to move towards an MR-only workflow. This work will be expanded to model based reconstruction, PD-weighted images and other types of applicators.« less

SU-E-T-237: Deformable Image Registration and Deformed Dose Composite for Volumetric Evaluation of Multimodal Gynecological Cancer Treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albani, D; Sherertz, T; Ellis, R

2015-06-15

Purpose: Radiotherapy plans for patients with cervical cancer treated with EBRT followed by HDR brachytherapy are optimized by constraining dose to organs at risk (OARs). Risk of treatment related toxicities is estimated based on the dose received to the hottest 2cc (D2cc) of the bladder, bowel, rectum, and sigmoid. To account for intrafractional variation in OAR volume and positioning, a dose deformation method is proposed for more accurate evaluation of dose distribution for these patients. Methods: Radiotherapy plans from five patients who received 50.4Gy pelvic EBRT followed by 30Gy in five fractions of HDR brachytherapy, using split-ring and tandem applicators,more » were retrospectively evaluated using MIM Software version 6.0. Dose accumulation workflows were used for initial deformation of EBRT and HDR planning CTs onto a common HDR planning CT. The Reg Refine tool was applied with user-specified local alignments to refine the deformation. Doses from the deformed images were transferred to the common planning CT. Deformed doses were scaled to the EQD2, following the linear-quadratic BED model (considered α/β ratio for tumor as 10, and 3 for rest of the tissues), and then combined to create the dose composite. MIM composite doses were compared to the clinically-reported plan assessments based upon the American Brachytherapy Society (ABS) guidelines for cervical HDR brachytherapy treatment. Results: Bladder D2cc exhibited significant reduction (−11.4%±3.85%, p< 0.02) when evaluated using MIM deformable dose composition. Differences observed for bowel, rectum, and sigmoid D2cc were not significant (−0.58±7.37%, −4.13%±13.7%, and 8.58%±4.71%, respectively and p>0.05 for all) relative to the calculated values used clinically. Conclusion: Application of deformable dose composite techniques may lead to more accurate total dose reporting and can allow for elevated dose to target structures with the assurance of not exceeding dose to OARs. Further study into deformable dose composition and correlation with clinical outcomes is warranted.« less

Linear Titration Curves of Acids and Bases.

PubMed

Joseph, N R

1959-05-29

The Henderson-Hasselbalch equation, by a simple transformation, becomes pH - pK = pA - pB, where pA and pB are the negative logarithms of acid and base concentrations. Sigmoid titration curves then reduce to straight lines; titration curves of polyelectrolytes, to families of straight lines. The method is applied to the titration of the dipeptide glycyl aminotricarballylic acid, with four titrable groups. Results are expressed as Cartesian and d'Ocagne nomograms. The latter is of a general form applicable to polyelectrolytes of any degree of complexity.

Correlation between solar flare productivity and photospheric vector magnetic fields

NASA Astrophysics Data System (ADS)

Cui, Yanmei; Wang, Huaning

2008-11-01

Studying the statistical correlation between the solar flare productivity and photospheric magnetic fields is very important and necessary. It is helpful to set up a practical flare forecast model based on magnetic properties and improve the physical understanding of solar flare eruptions. In the previous study ([Cui, Y.M., Li, R., Zhang, L.Y., He, Y.L., Wang, H.N. Correlation between solar flare productivity and photospheric magnetic field properties 1. Maximum horizontal gradient, length of neutral line, number of singular points. Sol. Phys. 237, 45 59, 2006]; from now on we refer to this paper as ‘Paper I’), three measures of the maximum horizontal gradient, the length of the neutral line, and the number of singular points are computed from 23990 SOHO/MDI longitudinal magnetograms. The statistical relationship between the solar flare productivity and these three measures is well fitted with sigmoid functions. In the current work, the three measures of the length of strong-shear neutral line, total unsigned current, and total unsigned current helicity are computed from 1353 vector magnetograms observed at Huairou Solar Observing Station. The relationship between the solar flare productivity and the current three measures can also be well fitted with sigmoid functions. These results are expected to be beneficial to future operational flare forecasting models.

Laparoscopic Approach for Metachronous Cecal and Sigmoid Volvulus

PubMed Central

Greenstein, Alexander J.; Zisman, Sharon R.

2010-01-01

Background: Metachronous colonic volvulus is a rare event that has never been approached laparoscopically. Methods: Here we discuss the case of a 63-year-old female with a metachronous sigmoid and cecal volvulus. Results: The patient underwent 2 separate successful laparoscopic resections. Discussion and Conclusion: The following is a discussion of the case and the laparoscopic technique, accompanied by a brief review of colonic volvulus. In experienced hands, laparoscopy is a safe approach for acute colonic volvulus. PMID:21605523

Colonic carcinoma presenting as strangulated inguinal hernia: report of two cases and review of the literature.

PubMed

Slater, R; Amatya, U; Shorthouse, A J

2008-09-01

Inguinal hernia and colonic carcinoma are common surgical conditions, yet carcinoma of the colon occurring within an inguinal hernia sac is rare. Of 25 reported cases, only one was a perforated sigmoid colon carcinoma in an inguinal hernia. We report two cases of sigmoid colon carcinoma, one of which had locally perforated. Each presented within a strangulated inguinal hernia. Oncologically correct surgery in these patients presents a technical challenge.

Elective laparoscopic recto-sigmoid resection for diverticular disease is suitable as a training operation.

PubMed

Bosker, Robbert; Hoogenboom, Froukje; Groen, Henk; Hoff, Christiaan; Ploeg, Rutger; Pierie, Jean-Pierre

2010-04-01

Some authors state that elective laparoscopic recto-sigmoid resection is more difficult for diverticular disease as compared with malignancy. For this reason, starting laparoscopic surgeons might avoid diverticulitis, making the implementation phase unnecessary long. The aim of this study was to determine whether laparoscopic resection for diverticular disease should be included during the implementation phase. All consecutive patients who underwent an elective laparoscopic recto-sigmoid resection in our hospital for diverticulitis or cancer from 2003 to 2007 were analysed. A total of 256 consecutive patients were included in this prospective cohort study. One hundred and fifty-one patients were operated on for diverticulitis and 105 for cancer. There was no significant difference in operation time (168 vs. 172 min), blood loss (189 vs. 208 ml), conversion rates (9.9% vs. 11.4%), hospital stay (8 vs. 8 days), total number of peroperative (2.3% vs. 1.6%) or postoperative complications (21.9% vs. 26.9%). The occurrence of anastomotic leakages was associated with higher American Society of Anesthesiologists (ASA) classification, which differed between the groups (86.8% vs. 64.8% ASA I-II, p < 0.001). Since there are no differences in operation time, blood loss, conversion rate and total complications, there is no need to avoid laparoscopic recto-sigmoid resection for diverticular disease early in the learning curve.

Laparoscopic peritoneal lavage: our experience and review of the literature.

PubMed

Parisi, Amilcare; Gemini, Alessandro; Desiderio, Jacopo; Petrina, Adolfo; Trastulli, Stefano; Grassi, Veronica; Sani, Marco; Pironi, Daniele; Santoro, Alberto

2016-01-01

Over the years various therapeutic techniques for diverticulitis have been developed. Laparoscopic peritoneal lavage (LPL) appears to be a safe and useful treatment, and it could be an effective alternative to colonic resection in emergency surgery. This prospective observational study aims to assess the safety and benefits of laparoscopic peritoneal lavage in perforated sigmoid diverticulitis. We surgically treated 70 patients urgently for complicated sigmoid diverticulitis. Thirty-two (45.7%) patients underwent resection of the sigmoid colon and creation of a colostomy (Hartmann technique); 21 (30%) patients underwent peritoneal laparoscopic lavage; 4 (5.7%) patients underwent colostomy by the Mikulicz technique; and the remaining 13 (18.6%) patients underwent resection of the sigmoid colon and creation of a colorectal anastomosis with a protective ileostomy. The 66 patients examined were divided into 3 groups: 32 patients were treated with urgent surgery according to the Hartmann procedure; 13 patients were treated with resection and colorectal anastomosis; 21 patients were treated urgently with laparoscopic peritoneal lavage. We had no intraoperative complications. The overall mortality was 4.3% (3 patients). In the LPL group the morbidity rate was 33.3%. Currently it cannot be said that LPL is better in terms of mortality and morbidity than colonic resection. These data may, however, be proven wrong by greater attention in the selection of patients to undergo laparoscopic peritoneal lavage.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chesny, D. L.; Oluseyi, H. M.; Orange, N. B.

We report on the identification of dynamic flaring non-potential structures on quiet Sun (QS) supergranular network scales. Data from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory allow for the high spatial and temporal resolution of this diverse class of compact structures. The rapidly evolving non-potential events presented here, with lifetimes <10 minutes, are on the order of 10″ in length. Thus, they contrast significantly with well-known active region (AR) non-potential structures such as high-temperature X-ray and EUV sigmoids (>100″) and micro-sigmoids (>10″) with lifetimes on the order of hours to days. The photospheric magnetic field environment derivedmore » from the Helioseismic and Magnetic Imager shows a lack of evidence for these flaring non-potential fields being associated with significant concentrations of bipolar magnetic elements. Of much interest to our events is the possibility of establishing them as precursor signatures of eruptive dynamics, similar to notions for AR sigmoids and micro-sigmoids, but associated with uneventful magnetic network regions. We suggest that the mixed network flux of QS-like magnetic environments, though unresolved, can provide sufficient free magnetic energy for flaring non-potential plasma structuring. The appearance of non-potential magnetic fields could be a fundamental process leading to self-organized criticality in the QS-like supergranular network and contribute to coronal heating, as these events undergo rapid helicial and vortical relaxations.« less

Management of Complications Following Emergency and Elective Surgery for Diverticulitis.

PubMed

Holmer, Christoph; Kreis, Martin E

2015-04-01

The clinical spectrum of sigmoid diverticulitis (SD) varies from asymptomatic diverticulosis to symptomatic disease with potentially fatal complications. Sigmoid colectomy with restoration of continuity has been the prevailing modality for treating acute and recurrent SD, and is often performed as a laparoscopy-assisted procedure. For elective sigmoid colectomy, the postoperative morbidity rate is 15-20% whereas morbidity rates reach up to 30% in patients who undergo emergency surgery for perforated SD. Some of the more common and serious surgical complications after sigmoid colectomy are anastomotic leaks and peritonitis, wound infections, small bowel obstruction, postoperative bleeding, and injuries to the urinary tract structures. Regarding the management of complications, it makes no difference whether the complication is a result of an emergency or an elective procedure. The present work gives an overview of the management of complications in the surgical treatment of SD based on the current literature. To achieve successful management, early diagnosis is mandatory in cases of deviation from the normal postoperative course. If diagnostic procedures fail to deliver a correlate for the clinical situation of the patient, re-laparotomy or re-laparoscopy still remain among the most important diagnostic and/or therapeutic principles in visceral surgery when a patient's clinical status deteriorates. The ability to recognize and successfully manage complications is a crucial part of the surgical treatment of diverticular disease and should be mastered by any surgeon qualified in this field.

Modeling the Collisional-Plastic Stress Transition for Bin Discharge of Granular Material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pannala, Sreekanth; Daw, C Stuart; FINNEY, Charles E A

2009-01-01

We propose a heuristic model for the transition between collisional and frictional/plastic stresses in the flow of granular material. Our approach is based on a physically motivated, nonlinear blending function that produces a weighted average of the limiting stresses, depending on the local void fraction in the flow field. Previously published stress models are utilized to describe the behavior in the collisional (Lun et al., 1984) and quasi-static limits (Schaeffer, 1987 and Syamlal et al., 1993). Sigmoidal and hyperbolic tangent functions are used to mimic the observed smooth yet rapid transition between the collisional and plastic stress zones. We implementmore » our stress transition model in an opensource multiphase flow solver, MFIX (Multiphase Flow with Interphase eXchanges, www.mfix.org) and demonstrate its application to a standard bin discharge problem. The model s effectiveness is illustrated by comparing computational predictions to the experimentally derived Beverloo correlation. With the correct choice of function parameters, the model predicts bin discharge rates within the error margins of the Beverloo correlation and is more accurate than one of the alternative granular stress models proposed in the literature. Although a second granular stress model in the literature is also reasonably consistent with the Beverloo correlation, we propose that our alternative blending function is likely to be more adaptable to situations with more complex solids properties (e.g., sticky solids).« less

Pharmacokinetics, pharmacodynamics and the pharmacokinetic/ pharmacodynamic relationship of zolpidem in healthy subjects.

PubMed

de Haas, S L; Schoemaker, R C; van Gerven, J M A; Hoever, P; Cohen, A F; Dingemanse, J

2010-11-01

Zolpidem is one of the most frequently prescribed hypnotics, as it is a very short-acting compound with relatively few side effects. Zolpidem's short duration of action is partly related to its short elimination half-life, but the associations between plasma levels and pharmacodynamic (PD) effects are not precisely known. In this study, the concentration-effect relationships for zolpidem were modelled. Zolpidem (10 mg) was administered in a double-blind, randomised, placebo-controlled trial to determine PD and pharmacokinetics (PK) in 14 healthy volunteers. Zolpidem was absorbed and eliminated quickly, with a median T(max) of 0.78 h (range: 0.33-2.50) and t(1/2) of 2.2 h. Zolpidem reduced saccadic peak velocity (SPV), adaptive tracking performance, electroencephalogram (EEG) alpha power and visual analogue scale (VAS) alertness score and increased body sway, EEG beta power and VAS 'feeling high'. Short- and long-term memory was not affected. Central nervous system effects normalised more rapidly than the decrease of plasma concentrations. For most effects, zolpidem's short duration of action could be adequately described by both a sigmoid E(max) model and a transit tolerance model. For SPV and EEG alpha power, the tolerance model seemed less suitable. These PK/PD models have different implications for the mechanism underlying zolpidem's short duration of action. A sigmoid E(max) model (which is based on ligand binding theory) would imply a threshold value for the drug's effective concentrations. A transit tolerance model (in which a hypothetical factor builds up with time that antagonises the effects of the parent compound) is compatible with a rapid reversible desensitisation of GABAergic subunits.

Hand-assisted laparoscopic sigmoid colectomy skills acquisition: augmented reality simulator versus human cadaver training models.

PubMed

Leblanc, Fabien; Senagore, Anthony J; Ellis, Clyde N; Champagne, Bradley J; Augestad, Knut M; Neary, Paul C; Delaney, Conor P

2010-01-01

The aim of this study was to compare a simulator with the human cadaver model for hand-assisted laparoscopic colorectal skills acquisition training. An observational prospective comparative study was conducted to compare the laparoscopic surgery training models. The study took place during the laparoscopic colectomy training course performed at the annual scientific meeting of the American Society of Colon and Rectal Surgeons. Thirty four practicing surgeons performed hand-assisted laparoscopic sigmoid colectomy on human cadavers (n = 7) and on an augmented reality simulator (n = 27). Prior laparoscopic colorectal experience was assessed. Trainers and trainees completed independently objective structured assessment forms. Training models were compared by trainees' technical skills scores, events scores, and satisfaction. Prior laparoscopic experience was similar in both surgeon groups. Generic and specific skills scores were similar on both training models. Generic events scores were significantly better on the cadaver model. The 2 most frequent generic events occurring on the simulator were poor hand-eye coordination and inefficient use of retraction. Specific events were scored better on the simulator and reached the significance limit (p = 0.051) for trainers. The specific events occurring on the cadaver were intestinal perforation and left ureter identification difficulties. Overall satisfaction was better for the cadaver than for the simulator model (p = 0.009). With regard to skills scores, the augmented reality simulator had adequate qualities for the hand-assisted laparoscopic colectomy training. Nevertheless, events scores highlighted weaknesses of the anatomical replication on the simulator. Although improvements likely will be required to incorporate the simulator more routinely into the colorectal training, it may be useful in its current form for more junior trainees or those early on their learning curve. Copyright 2010 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

SU-C-202-02: A Comprehensive Evaluation of Adaptive Daily Planning for Cervical Cancer HDR Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meerschaert, R; Paul, A; Zhuang, L

Purpose: To evaluate adaptive daily planning for cervical cancer patients who underwent high-dose-rate intra-cavitary brachytherapy (HDR-ICBT). Methods: This study included 22 cervical cancer patients who underwent 5 fractions of HDR ICBT. Regions of interest (ROIs) including high-risk clinical tumor volume (HR-CTV) and organs-at-risk (OARs) were manually contoured on daily CT images. All patients were treated with adaptive daily plans, which involved ROI delineation and dose optimization at each treatment fraction. Single treatment plans were retrospectively generated by applying the first treatment fraction’s dwell times adjusted for decay and dwell positions of the applicator to subsequent treatment fractions. Various existing similaritymore » metrics were calculated for the ROIs to quantify interfractional organ variations. A novel similarity score (JRARM) was established, which combined both volumetric overlap metrics (DSC, JSC, and RVD) and distance metrics (ASD, MSD, and RMSD). Linear regression was performed to determine a relationship between inter-fractional organ variations of various similarity metrics and D2cc variations from both plans. Wilcoxon Signed Rank Tests were used to assess adaptive daily plans and single plans by comparing EQD2 D2cc (α/β=3) for OARs. Results: For inter-fractional organ variations, the sigmoid demonstrated the greatest variations based on the JRARM and DSC similarity metrics. Comparisons between paired ROIs showed differences in JRARM scores and DSCs at each treatment fraction. RVD, MSD, and RMSD were found to be significantly correlated to D2cc variations for bladder and sigmoid. The comparison between plans found that adaptive daily planning provided lower EQD2 D2cc of OARs than single planning, specifically for the sigmoid (p=0.015). Conclusion: Substantial inter-fractional organ motion can occur during HDR-BT, which may significantly affect D2cc of OARs. Adaptive daily planning provides improved dose sparing for OARs compared to single planning.« less

Diverticular disease at colonoscopy in Lagos State, Nigeria.

PubMed

Oluyemi, Aderemi; Odeghe, Emuobor

2016-01-01

The upsurge in the reported cases of diverticular disease (DD) has led to a re-appraisal of the earlier held views that it was a rare entity in Nigeria. The advent of colonoscopy has contributed in no small way to this change. We sought to determine the clinical characteristics, indications for colonoscopy, and intra-procedural findings among these patients. A retrospective cross-sectional study was carried out on the colonoscopy records from four private endoscopy units based in Lagos State, Nigeria. The records were drawn from a 5-year period (August 2010 to July 2015). The endoscopy logs and reports were reviewed, and the bio data, indications, and colonoscopy findings were gleaned. A total of 265 colonoscopies were carried out in the stated period. Of these, 28 (10.6%) had DD. Of the patients with DD, 5 (17.9%) were females while 23 (82.1%) were males. Their ages ranged from 46 to 94 years (mean = 68.2 ± 11 years). Fifteen patients had been referred for the procedure on account of hematochezia alone (15 = 53.6%). Other reasons for referral included abdominal pain alone (2 = 7%), hematochezia plus abdominal pain (5 = 17.9%), and change in bowel habits (3 = 10.8%). Ten (35%) patients had pan-colonic involvement. Regional disease involved the right side alone in only one case (3.5%) while the other combinations of sites are as follows; 6 (21.4%) in the sigmoid colon alone, 2 (7%) in the descending colon alone, 5 (17.9%) in the sigmoid-descending colon, 4 (14.3%) in the sigmoid-descending-transverse colon, thus the sigmoid colon was involved in 25 (89.3%) cases. Five cases (17.9%) had endoscopic features suggestive of diverticulitis. DD should no longer be regarded as a rare problem in the Nigerian patient. The study findings support the notion of higher prevalence among the elderly, in males, and of sigmoid colon involvement.

Robust back-stepping output feedback trajectory tracking for quadrotors via extended state observer and sigmoid tracking differentiator

NASA Astrophysics Data System (ADS)

Shao, Xingling; Liu, Jun; Wang, Honglun

2018-05-01

In this paper, a robust back-stepping output feedback trajectory tracking controller is proposed for quadrotors subject to parametric uncertainties and external disturbances. Based on the hierarchical control principle, the quadrotor dynamics is decomposed into translational and rotational subsystems to facilitate the back-stepping control design. With given model information incorporated into observer design, a high-order extended state observer (ESO) that relies only on position measurements is developed to estimate the remaining unmeasurable states and the lumped disturbances in rotational subsystem simultaneously. To overcome the problem of "explosion of complexity" in the back-stepping design, the sigmoid tracking differentiator (STD) is introduced to compute the derivative of virtual control laws. The advantage is that the proposed controller via output-feedback scheme not only can ensure good tracking performance using very limited information of quadrotors, but also has the ability of handling the undesired uncertainties. The stability analysis is established using the Lyapunov theory. Simulation results demonstrate the effectiveness of the proposed control scheme in achieving a guaranteed tracking performance with respect to an 8-shaped reference trajectory.

A CIRCULAR-RIBBON SOLAR FLARE FOLLOWING AN ASYMMETRIC FILAMENT ERUPTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Chang; Deng, Na; Lee, Jeongwoo

The dynamic properties of flare ribbons and the often associated filament eruptions can provide crucial information on the flaring coronal magnetic field. This Letter analyzes the GOES-class X1.0 flare on 2014 March 29 (SOL2014-03-29T17:48), in which we found an asymmetric eruption of a sigmoidal filament and an ensuing circular flare ribbon. Initially both EUV images and a preflare nonlinear force-free field model show that the filament is embedded in magnetic fields with a fan-spine-like structure. In the first phase, which is defined by a weak but still increasing X-ray emission, the western portion of the sigmoidal filament arches upward andmore » then remains quasi-static for about five minutes. The western fan-like and the outer spine-like fields display an ascending motion, and several associated ribbons begin to brighten. Also found is a bright EUV flow that streams down along the eastern fan-like field. In the second phase that includes the main peak of hard X-ray (HXR) emission, the filament erupts, leaving behind two major HXR sources formed around its central dip portion and a circular ribbon brightened sequentially. The expanding western fan-like field interacts intensively with the outer spine-like field, as clearly seen in running difference EUV images. We discuss these observations in favor of a scenario where the asymmetric eruption of the sigmoidal filament is initiated due to an MHD instability and further facilitated by reconnection at a quasi-null in corona; the latter is in turn enhanced by the filament eruption and subsequently produces the circular flare ribbon.« less

Non-linear Growth Models in Mplus and SAS

PubMed Central

Grimm, Kevin J.; Ram, Nilam

2013-01-01

Non-linear growth curves or growth curves that follow a specified non-linear function in time enable researchers to model complex developmental patterns with parameters that are easily interpretable. In this paper we describe how a variety of sigmoid curves can be fit using the Mplus structural modeling program and the non-linear mixed-effects modeling procedure NLMIXED in SAS. Using longitudinal achievement data collected as part of a study examining the effects of preschool instruction on academic gain we illustrate the procedures for fitting growth models of logistic, Gompertz, and Richards functions. Brief notes regarding the practical benefits, limitations, and choices faced in the fitting and estimation of such models are included. PMID:23882134

Comments on new classification, treatment algorithm and prognosis-estimating systems for sigmoid volvulus and ileosigmoid knotting: necessity and utility.

PubMed

Aksungur, N; Korkut, E

2018-05-24

We read Atamanalp classification, treatment algorithm and prognosis-estimating systems for sigmoid volvulus (SV) and ileosigmoid knotting (ISK) in Colorectal Disease [1,2]. Our comments relate to necessity and utility of these new classification systems. Classification or staging systems are generally used in malignant or premalignant pathologies such as colorectal cancers [3] or polyps [4]. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Spontaneous uretero-sigmoid fistula secondary to calculus

PubMed Central

Marzouk, Ines; Moussa, Makram; Saadallah, Lotfi; Bouchoucha, Sami; Hendaoui, Lotfi

2016-01-01

A 25-year-old man was referred to the urology department after a subacute history of left back pain, burning micturition associated with pneumaturia and fecaluria. Ultrasonography was performed showing hydronephrosis, and plain film radiography demonstrated a long vertical left pelvic calculi. Uro-computed tomography (CT) combined with a water enema CT showed a 10 cm long calculus with the cranial extremity fistulating the sigmoidal wall. Surgical treatment included left nephroureterectomy and sigmoidectomy with a colorectal anastomosis. Postoperative course was uneventful. PMID:28096928

Threonine deaminase from extremely halophilic bacteria - Cooperative substrate kinetics and salt dependence.

NASA Technical Reports Server (NTRS)

Lieberman, M. M.; Lanyi, J. K.

1972-01-01

The effect of salt on the activity, stability, and allosteric properties of catabolic threonine deaminase from Halobacterium cutirubrum was studied. The enzyme exhibits sigmoidal kinetics with the substrate, threonine. The Hill slope is 1.55 at pH 10. The enzyme is activated by ADP at low substrate concentrations. In the presence of this effector, sigmoidal kinetics are no longer observed. At pH 10, in the absence of ADP, enzyme activity increases with increasing NaCl concentration from 0 to 4 M.

Application of an adaptive neuro-fuzzy inference system to ground subsidence hazard mapping

NASA Astrophysics Data System (ADS)

Park, Inhye; Choi, Jaewon; Jin Lee, Moung; Lee, Saro

2012-11-01

We constructed hazard maps of ground subsidence around abandoned underground coal mines (AUCMs) in Samcheok City, Korea, using an adaptive neuro-fuzzy inference system (ANFIS) and a geographical information system (GIS). To evaluate the factors related to ground subsidence, a spatial database was constructed from topographic, geologic, mine tunnel, land use, and ground subsidence maps. An attribute database was also constructed from field investigations and reports on existing ground subsidence areas at the study site. Five major factors causing ground subsidence were extracted: (1) depth of drift; (2) distance from drift; (3) slope gradient; (4) geology; and (5) land use. The adaptive ANFIS model with different types of membership functions (MFs) was then applied for ground subsidence hazard mapping in the study area. Two ground subsidence hazard maps were prepared using the different MFs. Finally, the resulting ground subsidence hazard maps were validated using the ground subsidence test data which were not used for training the ANFIS. The validation results showed 95.12% accuracy using the generalized bell-shaped MF model and 94.94% accuracy using the Sigmoidal2 MF model. These accuracy results show that an ANFIS can be an effective tool in ground subsidence hazard mapping. Analysis of ground subsidence with the ANFIS model suggests that quantitative analysis of ground subsidence near AUCMs is possible.

Perceived annoyance from environmental odors and association with atmospheric ammonia levels in non-urban residential communities: a cross-sectional study

PubMed Central

2012-01-01

Objective Odor exposure is an environmental stressor that is responsible of many citizens complains about air pollution in non-urban areas. However, information about the exposure-response relation is scarce. One of the main challenges is to identify a measurable compound that can be related with odor annoyance responses. We investigated the association between regional and temporal variation of ammonia (NH3) concentrations in five Danish non-urban regions and environmental odor annoyance as perceived by the local residents. Methods A cross-sectional study where NH3 concentration was obtained from the national air quality monitoring program and from emission-dispersion modelling, and odor pollution perception from questionnaires. The exposure-response model was a sigmoid model. Linear regression analyses were used to estimate the model constants after equation transformations. The model was validated using leave-one-out cross validation (LOOCV) statistical method. Results About 45% of the respondents were annoyed by odor pollution at their residential areas. The perceived odor was characterized by all respondents as animal waste odor. The exposure-annoyance sigmoid model showed that the prevalence of odor annoyance was significantly associated with NH3 concentrations (measured and estimated) at the local air quality monitoring stations (p < 0.01,R2 = 0.99; and p < 0.05,R2 = 0.93; respectively). Prediction errors were below 5.1% and 20% respectively. The seasonal pattern of odor perception was associated with the seasonal variation in NH3 concentrations (p < 0.001, adjusted R2 = 0.68). Conclusion The results suggest that atmospheric NH3 levels at local air quality stations could be used as indicators of prevalence of odor annoyance in non-urban residential communities. PMID:22513250

Assessing the Combined Antibacterial Effect of Isoniazid and Rifampin on Four Mycobacterium tuberculosis Strains Using In Vitro Experiments and Response-Surface Modeling

PubMed Central

2017-01-01

ABSTRACT While isoniazid and rifampin have been the cornerstone of tuberculosis therapy caused by drug-susceptible Mycobacterium tuberculosis for more than 40 years, their combined action has never been thoroughly assessed by modern quantitative pharmacology approaches. The aims of this work were to perform in vitro experiments and mathematical modeling of the antibacterial effect of isoniazid and rifampin alone and in combination against various strains of Mycobacterium tuberculosis. After MIC determination of H37Rv and three strains belonging to the Beijing, Euro-American, and Indo-Oceanic lineages, the antibacterial effects of isoniazid and rifampin alone and in combination were studied in static time-kill experiments. A sigmoidal maximum effect model (Hill equation) and a response-surface model were used to describe the effect of the drugs alone and in combination, respectively. The killing effect of isoniazid and rifampin alone were well described by the Hill equation. Rifampin displayed a more concentration-dependent effect than isoniazid around the MIC. The pharmacodynamics parameters of each drug (maximal effect, median effect concentration, and coefficient of sigmoidicity) were quite similar between the four strains. The response-surface model from Minto et al. fit data of combined effect very well with low bias and imprecision (C. F. Minto, T. W. Schnider, T. G. Short, K. M. Gregg, A. Gentilini, Anesthesiology 92:1603–1616, 2000, https://doi.org/10.1097/00000542-200006000-00017). Response-surface modeling showed that the combined action of isoniazid and rifampin was synergistic for the H37Rv, Beijing, and Euro-American strains but only additive for the Indo-Oceanic strain. This study can serve as a motivating example for preclinical evaluation of combined action of antituberculous drugs. PMID:29061753

Comparison of Two Coronal Magnetic Field Models to Reconstruct a Sigmoidal Solar Active Region with Coronal Loops

NASA Astrophysics Data System (ADS)

Duan, Aiying; Jiang, Chaowei; Hu, Qiang; Zhang, Huai; Gary, G. Allen; Wu, S. T.; Cao, Jinbin

2017-06-01

Magnetic field extrapolation is an important tool to study the three-dimensional (3D) solar coronal magnetic field, which is difficult to directly measure. Various analytic models and numerical codes exist, but their results often drastically differ. Thus, a critical comparison of the modeled magnetic field lines with the observed coronal loops is strongly required to establish the credibility of the model. Here we compare two different non-potential extrapolation codes, a nonlinear force-free field code (CESE-MHD-NLFFF) and a non-force-free field (NFFF) code, in modeling a solar active region (AR) that has a sigmoidal configuration just before a major flare erupted from the region. A 2D coronal-loop tracing and fitting method is employed to study the 3D misalignment angles between the extrapolated magnetic field lines and the EUV loops as imaged by SDO/AIA. It is found that the CESE-MHD-NLFFF code with preprocessed magnetogram performs the best, outputting a field that matches the coronal loops in the AR core imaged in AIA 94 Å with a misalignment angle of ˜10°. This suggests that the CESE-MHD-NLFFF code, even without using the information of the coronal loops in constraining the magnetic field, performs as good as some coronal-loop forward-fitting models. For the loops as imaged by AIA 171 Å in the outskirts of the AR, all the codes including the potential field give comparable results of the mean misalignment angle (˜30°). Thus, further improvement of the codes is needed for a better reconstruction of the long loops enveloping the core region.

Comparison of Two Coronal Magnetic Field Models to Reconstruct a Sigmoidal Solar Active Region with Coronal Loops

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, Aiying; Zhang, Huai; Jiang, Chaowei

Magnetic field extrapolation is an important tool to study the three-dimensional (3D) solar coronal magnetic field, which is difficult to directly measure. Various analytic models and numerical codes exist, but their results often drastically differ. Thus, a critical comparison of the modeled magnetic field lines with the observed coronal loops is strongly required to establish the credibility of the model. Here we compare two different non-potential extrapolation codes, a nonlinear force-free field code (CESE–MHD–NLFFF) and a non-force-free field (NFFF) code, in modeling a solar active region (AR) that has a sigmoidal configuration just before a major flare erupted from themore » region. A 2D coronal-loop tracing and fitting method is employed to study the 3D misalignment angles between the extrapolated magnetic field lines and the EUV loops as imaged by SDO /AIA. It is found that the CESE–MHD–NLFFF code with preprocessed magnetogram performs the best, outputting a field that matches the coronal loops in the AR core imaged in AIA 94 Å with a misalignment angle of ∼10°. This suggests that the CESE–MHD–NLFFF code, even without using the information of the coronal loops in constraining the magnetic field, performs as good as some coronal-loop forward-fitting models. For the loops as imaged by AIA 171 Å in the outskirts of the AR, all the codes including the potential field give comparable results of the mean misalignment angle (∼30°). Thus, further improvement of the codes is needed for a better reconstruction of the long loops enveloping the core region.« less

Physiologic study of the terminal digestive tract in chronic painful constipation.

PubMed Central

Meunier, P

1986-01-01

A manometric study of the sigmoid colon and of the anorectum was undertaken in 65 chronically constipated patients complaining of abdominal pain, and in a control group of 23 healthy volunteers. Rectal compliance was tested in both groups. The sigmoid motility study allowed for the segregation of the constipated patients into three groups: hypokinesia (12 cases), normokinesia (34 cases), hyperkinesia (19 cases). Rectal manometry showed anal hypertony in 24 patients, impaired rectal conscious sensitivity in 12 subjects, and normal functions in the remaining cases. The rectal compliance study disclosed a decreased compliance in 15 cases and increased compliance in 13 other patients. In 12 cases disordered sigmoid motility was the only abnormality; in 10 cases only a rectoanal abnormality was found. Most of the patients (52%) exhibited miscellaneous disorders. In contrast, all parameters were normal in nine subjects. No consistent pattern of motility disorders was thus demonstrated in this clinically homogeneous group of patients with chronic, painful, constipation. PMID:3758814

[A case of a perivascular epithelioid cell tumor mimicking colon cancer].

PubMed

Cho, Young Whan; Kim, Kyung Jo; Ye, Byong Duk; Byeon, Jeong Sik; Myung, Seung Jae; Yang, Suk Kyun; Kim, Jin Ho

2012-12-01

Perivascular epithelioid cell tumor (PEComa) is extremely rare, which originated from mesenchymal cells in the intestine, and composed of histologically and immunohistochemically distinctive perivascular epithelioid cells. We report here on a case of PEComa in the sigmoid colon. A 62-year-old woman presented with hematochzia 10 days ago. Her abdominal computed tomography scan showed a 5 cm sized intraluminal fungating heterogeneously enhanced, high density mass, which infiltrated pericolic tissue surrounding the sigmoid colon. Colonoscopy showed a purple colored polypoid mass with lobulating contour in the sigmoid colon. She underwent laparoscopic anterior resection. On the histologic examination, the tumor consisted of polygonal epithelioid cells with sheet-like growth of nests, which looked like alveolar tissues in lung. The tumor cells were strongly positive stained with human melanoma black-45 (HMB-45). Pathologic examination was compatible with PEComa. Sixteen months after surgery, she did well without tumor recurrence after surgery. We review the literatures concerning PEComa of the intestine focusing on endoscopic findings.

Laparoscopic promontofixation for the treatment of recurrent sigmoid neovaginal prolapse: case report and systematic review of the literature.

PubMed

Kondo, William; Ribeiro, Reitan; Tsumanuma, Fernanda Keiko; Zomer, Monica Tessmann

2012-01-01

Prolapse of a sigmoid neovagina, created in patients with congenital vaginal aplasia, is rare. In correcting this condition, preservation of coital function and restoration of the vaginal axis should be of primary interest. A 34-year-old woman with vaginal agenesis underwent vaginoplasty using sigmoid colon. Almost 6 years after the initial operation, she started complaining of a bearing-down sensation and an increase in vaginal discharge. She underwent 2 open surgeries and one vaginal surgery to treat the prolapse with no success. She came to our service and at vaginal examination the neovagina protruded approximately 5 cm beyond the hymen. The prolapse was treated successfully using a laparoscopic approach to suspend the neovagina to the sacral promontory (laparoscopic promontofixation). Prolapse of an artificially created vagina is a rare occurrence, without a standard treatment. Laparoscopy may be an alternative approach to restore the neovagina without compromising its function. Copyright © 2012 AAGL. Published by Elsevier Inc. All rights reserved.

Malignant sigmoidoduodenal fistula

PubMed Central

Shapey, I.M.; Mahmood, K.; Solkar, M.H.

2014-01-01

INTRODUCTION Duodenocolic fistula is a rare complication of malignant colonic disease especially when involving and originating from the sigmoid colon. We aim to discuss the unusual clinical presentation of this case as well as the investigation and management of duodenocolic fistulas. PRESENTATION OF CASE A 91 year old lady presented as an emergency to a general surgical service at a District General Hospital with diarrhoea, vomiting and weight loss. Computed Tomography (CT) reported a large ovarian cyst elevating the sigmoid colon into immediate proximity of the duodenum. Adenocarcinoma was confirmed on histology obtained by colonoscopy. A classic apple core lesion with fistulating tract from the sigmoid colon to the duodenum was synchronously demonstrated on barium enema. DISCUSSION Sigmoido-duodenal fistulae represent a complex manifestation of gastrointestinal pathologies. CONCLUSION Management options must be considered in the context of patient wishes, their co-morbidities, and predicted post-operative outcome. In most cases this is likely to represent a non-operative approach, however surgical resection may benefit selected cases on occasion. PMID:25460456

Malignant sigmoidoduodenal fistula.

PubMed

Shapey, I M; Mahmood, K; Solkar, M H

2014-01-01

Duodenocolic fistula is a rare complication of malignant colonic disease especially when involving and originating from the sigmoid colon. We aim to discuss the unusual clinical presentation of this case as well as the investigation and management of duodenocolic fistulas. A 91 year old lady presented as an emergency to a general surgical service at a District General Hospital with diarrhoea, vomiting and weight loss. Computed Tomography (CT) reported a large ovarian cyst elevating the sigmoid colon into immediate proximity of the duodenum. Adenocarcinoma was confirmed on histology obtained by colonoscopy. A classic apple core lesion with fistulating tract from the sigmoid colon to the duodenum was synchronously demonstrated on barium enema. Sigmoido-duodenal fistulae represent a complex manifestation of gastrointestinal pathologies. Management options must be considered in the context of patient wishes, their co-morbidities, and predicted post-operative outcome. In most cases this is likely to represent a non-operative approach, however surgical resection may benefit selected cases on occasion. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Vaginal stump metastasis from sigmoid colon cancer.

PubMed

Tanaka, Tomohito; Kanda, Takayoshi; Sakaguchi, Satoru; Munakata, Satoru; Ohmichi, Masahide

2012-01-01

Vaginal metastasis from organs other than the uterus is rare. Generally, patients with vaginal metastasis from colorectal cancer have a dismal prognosis. Although biopsy is the best method to make the diagnosis, massive bleeding may occur. On the other hand, liquid-based cytology (LBC) has the utility to perform immunocytochemistry on additional unstained slides: we can make a diagnosis with several immunocytochemical findings. A 67-year-old postmenopausal female presented to our hospital with vaginal bleeding. The patient had undergone colectomy because of her stage III sigmoid colon cancer 3 years earlier. The patient had also undergone hysterectomy for cervical cancer 30 years earlier. LBC from the vaginal stump revealed adenocarcinoma. Immunocytochemically, cancer cells were negative for cytokeratin 7 and positive for cytokeratin 20, which suggested metastasis from the sigmoid colon cancer; the diagnosis was made without a biopsy. When the patient has a metastatic lesion from colon adenocarcinoma, LBC with immunocytochemistry is useful in making a diagnosis. Copyright © 2012 S. Karger AG, Basel.

Individual surgeon practice is the most important factor influencing diverting loop ileostomy creation for patients undergoing sigmoid colectomy for diverticulitis.

PubMed

Benlice, Cigdem; Delaney, Conor P; Liska, David; Hrabe, Jennifer; Steele, Scott; Gorgun, Emre

2018-03-01

To identify factors associated with diverting ileostomy creation (DLI) in patients undergoing sigmoid colectomy for diverticular disease in a high volume colorectal unit and to obtain information for better preoperative patient counseling. Patients who underwent sigmoid colectomy with colorectal anastomosis with or without DLI for diverticulitis between 01/1994-12/2014 were identified. Preoperative characteristics, surgeon practice year, individual surgeon and postoperative outcomes were compared between patients with DLI or not. 1320 patients were identified and DLI was created in 204 (15.4%) patients. DLI creation was associated with older age (p < 0.001), female gender (p = 0.01), higher ASA-class (p < 0.001), hypertension (p = 0.01), DM(p < 0.001), renal comorbidities (p < 0.001), preoperative steroid use (p = 0.03), preoperative anemia (p = 0.004), and open surgery (p < 0.001). While ileostomy creation rates did not vary over the years during the study period or with increased surgeons' experience, surgeon identity had significant impact on ileostomy creation (Rate range 6.8-60.7%, p < 0.001). Multivariate logistic regression analysis revealed that individual surgeon, open approach, preoperative steroid use, and disease-related factors remained independently associated with DLI creation. Individual surgeon's practice affects the rate of diverting ileostomy creation in patients undergoing sigmoid colectomy for diverticular disease. Copyright © 2017 Elsevier Inc. All rights reserved.

Sigmoid sinus cortical plate dehiscence induces pulsatile tinnitus through amplifying sigmoid sinus venous sound.

PubMed

Tian, Shan; Wang, Lizhen; Yang, Jiemeng; Mao, Rui; Liu, Zhaohui; Fan, Yubo

2017-02-08

Sigmoid sinus cortical plate dehiscence (SSCPD) is common in pulsatile tinnitus (PT) patients, and is treated through SSCPD resurfacing surgery in clinic, but the bio-mechanism is not clear as so far. This study aimed to clarify the bio-mechanism of PT sensation induced by SSCPD, and quantify the relationship of cortical plate (CP) thickness and PT sensation intensity. It was hypothesized that SSCPD would induce PT through significantly amplifying sigmoid sinus (SS) venous sound in this study. Finite element (FE) analysis based on radiology data of typical patient was used to verify this hypothesis, and was validated with clinical reports. In cases with different CP thickness, FE simulations of SS venous sound generation and propagation procedure were performed, involving SS venous flow field, vibration response of tissue overlying dehiscence area (including SS vessel wall and CP) and sound propagation in temporal bone air cells. It was shown in results that SS venous sound at tympanic membrane was 56.9dB in SSCPD case and -45.2dB in intact CP case, and was inaudible in all thin CP cases. It was concluded that SSCPD would directly induce PT through significantly amplifying SS venous sound, and thin CP would not be the only pathophysiology of PT. This conclusion would provide a theoretical basis for the design of SSCPD resurfacing surgery for PT patients with SSCPD or thin CP. Copyright © 2017 Elsevier Ltd. All rights reserved.

The antibacterial activity of chlorhexidine digluconate against Streptococcus mutans biofilms follows sigmoidal patterns.

PubMed

Lee, Dae-Woo; Jung, Ji-Eun; Yang, Yeon-Mi; Kim, Jae-Gon; Yi, Ho-Keun; Jeon, Jae-Gyu

2016-10-01

The aim of this study was to determine the pattern of the antibacterial activity of chlorhexidine digluconate (CHX) against mature Streptococcus mutans biofilms. Streptococcus mutans biofilms were formed on saliva-coated hydroxyapatite discs and then treated with 0-20% CHX, once, three times, or five times (1 min per treatment) during the period of mature biofilm formation (beyond 46 h). After the treatments, the colony-forming unit (CFU) counts of the treated biofilms were determined. The pH values of the spent culture medium were also determined to investigate the change in pH resulting from the antibacterial activity of CHX. The relationships between the concentration of CHX and the CFU counts and the concentration of CHX and culture medium pH, relative to the number of treatments performed, were evaluated using a sigmoidal curve-fitting procedure. The changes in CFU counts and culture medium pH followed sigmoidal curves and were dependent on the concentration of CHX (R 2 = 0.99). The sigmoidal curves were left-shifted with increasing number of treatments. Furthermore, the culture-medium pH of the treated biofilms increased as their CFU counts decreased. The lowest CHX concentration to increase culture-medium pH above the critical pH also decreased as the number of treatments increased. These results may provide fundamental information for selecting the appropriate CHX concentrations to treat S. mutans biofilms. © 2016 Eur J Oral Sci.

Sigmoid stenosis caused by diverticulitis vs. carcinoma: usefulness of sonographic features for their differentiation in the emergency setting.

PubMed

Ripollés, Tomás; Martínez-Pérez, María Jesús; Gómez Valencia, Diana Patricia; Vizuete, José; Martín, Gregorio

2015-10-01

To retrospectively evaluate the accuracy of ultrasound as a diagnostic method for differentiating acute diverticulitis from colon cancer in patients with sigmoid colon stenosis. Ultrasound examinations of 91 consecutive patients with sigmoid stenosis (50 diverticulitis and 41 colon cancers) were reviewed by two trained radiologists. Sixty-five (71%) patients presented with acute abdominal symptoms. Thirteen sonographic criteria retrieved from the literature were evaluated to differentiate benign from malignant strictures. A score including all parameters which showed significant differences between benign vs. malignant was built. Sensitivity, specificity, accuracy, and positive or negative predictive values of each sonographic sign, the overall diagnosis, and sonographic score were calculated. Loss of the bowel wall stratification was the most reliable criteria for the diagnosis of malignancy (92% and 94% of sensitivity and specificity, respectively), and the best inter-radiologist agreement (κ = 0.848). Adjacent lymph nodes were the most specific feature (98%) for colon cancer, but its sensitivity was low. Global assessment could differentiate both diseases with high sensitivity (92-94.9%) and specificity (98-100%). Sonographic score >3 enabled differentiation of carcinoma from diverticulitis with 95% sensitivity and 92-94% specificity, with an area under the ROC curve of 0.98-0.987. There were no significant differences in the results between patients with acute and nonacute abdominal symptoms. The combination of several morphological sonographic findings using a score can differentiate most cases of diverticulitis from colon carcinoma in sigmoid strictures.

Solo-Surgeon Single-Port Laparoscopic Anterior Resection for Sigmoid Colon Cancer: Comparative Study.

PubMed

Choi, Byung Jo; Jeong, Won Jun; Kim, Say-June; Lee, Sang Chul

2018-03-01

To report our experience with solo-surgeon, single-port laparoscopic anterior resection (solo SPAR) for sigmoid colon cancer. Data from sigmoid colon cancer patients who underwent anterior resections (ARs) using the single-port, solo surgery technique (n = 31) or the conventional single-port laparoscopic technique (n = 45), between January 2011 and July 2016, were retrospectively analyzed. In the solo surgeries, making the transumbilical incision into the peritoneal cavity was facilitated through the use of a self-retaining retractor system. After establishing a single port through the umbilicus, an adjustable mechanical camera holder replaced the human scope assistant. Patient and tumor characteristics and operative, pathologic, and postoperative outcomes were compared. The operative times and estimated blood losses were similar for the patients in both treatment groups. In addition, most of the postoperative variables were comparable between the two groups, including postoperative complications and hospital stays. In the solo SPAR group, comparable lymph nodes were attained, and sufficient proximal and distal cut margins were obtained. The difference in the proximal cut margin significantly favored the solo SPAR, compared with the conventional AR group (P = .000). This study shows that solo SPAR, using a passive camera system, is safe and feasible for use in sigmoid colon cancer surgery, if performed by an experienced laparoscopic surgeon. In addition to reducing the need for a surgical assistant, the oncologic requirements, including adequate margins and sufficient lymph node harvesting, could be fulfilled. Further evaluations, including prospective randomized studies, are warranted.

Hooked Flare Ribbons and Flux-rope-related QSL Footprints

NASA Astrophysics Data System (ADS)

Zhao, Jie; Gilchrist, Stuart A.; Aulanier, Guillaume; Schmieder, Brigitte; Pariat, Etienne; Li, Hui

2016-05-01

We studied the magnetic topology of active region 12158 on 2014 September 10 and compared it with the observations before and early in the flare that begins at 17:21 UT (SOL2014-09-10T17:45:00). Our results show that the sigmoidal structure and flare ribbons of this active region observed by the Solar Dynamics Observatory/Atmospheric Imaging Assembly can be well reproduced from a Grad-Rubin nonlinear force-free field extrapolation method. Various inverse-S- and inverse-J-shaped magnetic field lines, which surround a coronal flux rope, coincide with the sigmoid as observed in different extreme-ultraviolet wavelengths, including its multithreaded curved ends. Also, the observed distribution of surface currents in the magnetic polarity where it was not prescribed is well reproduced. This validates our numerical implementation and setup of the Grad-Rubin method. The modeled double inverse-J-shaped quasi-separatrix layer (QSL) footprints match the observed flare ribbons during the rising phase of the flare, including their hooked parts. The spiral-like shape of the latter may be related to a complex pre-eruptive flux rope with more than one turn of twist, as obtained in the model. These ribbon-associated flux-rope QSL footprints are consistent with the new standard flare model in 3D, with the presence of a hyperbolic flux tube located below an inverse-teardrop-shaped coronal QSL. This is a new step forward forecasting the locations of reconnection and ribbons in solar flares and the geometrical properties of eruptive flux ropes.

Data-Driven Method to Estimate Nonlinear Chemical Equivalence.

PubMed

Mayo, Michael; Collier, Zachary A; Winton, Corey; Chappell, Mark A

2015-01-01

There is great need to express the impacts of chemicals found in the environment in terms of effects from alternative chemicals of interest. Methods currently employed in fields such as life-cycle assessment, risk assessment, mixtures toxicology, and pharmacology rely mostly on heuristic arguments to justify the use of linear relationships in the construction of "equivalency factors," which aim to model these concentration-concentration correlations. However, the use of linear models, even at low concentrations, oversimplifies the nonlinear nature of the concentration-response curve, therefore introducing error into calculations involving these factors. We address this problem by reporting a method to determine a concentration-concentration relationship between two chemicals based on the full extent of experimentally derived concentration-response curves. Although this method can be easily generalized, we develop and illustrate it from the perspective of toxicology, in which we provide equations relating the sigmoid and non-monotone, or "biphasic," responses typical of the field. The resulting concentration-concentration relationships are manifestly nonlinear for nearly any chemical level, even at the very low concentrations common to environmental measurements. We demonstrate the method using real-world examples of toxicological data which may exhibit sigmoid and biphasic mortality curves. Finally, we use our models to calculate equivalency factors, and show that traditional results are recovered only when the concentration-response curves are "parallel," which has been noted before, but we make formal here by providing mathematical conditions on the validity of this approach.

Urban chaos and replacement dynamics in nature and society

NASA Astrophysics Data System (ADS)

Chen, Yanguang

2014-11-01

Replacements resulting from competition are ubiquitous phenomena in both nature and society. The evolution of a self-organized system is always a physical process substituting one type of components for another type of components. A logistic model of replacement dynamics has been proposed in terms of technical innovation and urbanization, but it fails to arouse widespread attention in the academia. This paper is devoted to laying the foundations of general replacement principle by using analogy and induction. The empirical base of this study is urban replacement, including urbanization and urban growth. The sigmoid functions can be employed to model various processes of replacement. Many mathematical methods such as allometric scaling and head/tail breaks can be applied to analyzing the processes and patterns of replacement. Among varied sigmoid functions, the logistic function is the basic and the simplest model of replacement dynamics. A new finding is that replacement can be associated with chaos in a nonlinear system, e.g., urban chaos is just a part of replacement dynamics. The aim of developing replacement theory is at understanding complex interaction and conversion. This theory provides a new way of looking at urbanization, technological innovation and diffusion, Volterra-Lotka’s predator-prey interaction, man-land relation, and dynastic changes resulting from peasant uprising, and all that. Especially, the periodic oscillations and chaos of replacement dynamics can be used to explain and predict the catastrophic occurrences in the physical and human systems.

Agent-based computational models to explore diffusion of medical innovations among cardiologists.

PubMed

Borracci, Raul A; Giorgi, Mariano A

2018-04-01

Diffusion of medical innovations among physicians rests on a set of theoretical assumptions, including learning and decision-making under uncertainty, social-normative pressures, medical expert knowledge, competitive concerns, network performance effects, professional autonomy or individualism and scientific evidence. The aim of this study was to develop and test four real data-based, agent-based computational models (ABM) to qualitatively and quantitatively explore the factors associated with diffusion and application of innovations among cardiologists. Four ABM were developed to study diffusion and application of medical innovations among cardiologists, considering physicians' network connections, leaders' opinions, "adopters' categories", physicians' autonomy, scientific evidence, patients' pressure, affordability for the end-user population, and promotion from companies. Simulations demonstrated that social imitation among local cardiologists was sufficient for innovation diffusion, as long as opinion leaders did not act as detractors of the innovation. Even in the absence of full scientific evidence to support innovation, up to one-fifth of cardiologists could accept it when local leaders acted as promoters. Patients' pressure showed a large effect size (Cohen's d > 1.2) on the proportion of cardiologists applying an innovation. Two qualitative patterns (speckled and granular) appeared associated to traditional Gompertz and sigmoid cumulative distributions. These computational models provided a semiquantitative insight on the emergent collective behavior of a physician population facing the acceptance or refusal of medical innovations. Inclusion in the models of factors related to patients' pressure and accesibility to medical coverage revealed the contrast between accepting and effectively adopting a new product or technology for population health care. Copyright © 2018 Elsevier B.V. All rights reserved.

Simultaneous and iterative weighted regression analysis of toxicity tests using a microplate reader.

PubMed

Galgani, F; Cadiou, Y; Gilbert, F

1992-04-01

A system is described for determination of LC50 or IC50 by an iterative process based on data obtained from a plate reader using a marine unicellular alga as a target species. The esterase activity of Tetraselmis suesica on fluorescein diacetate as a substrate was measured using a fluorescence titerplate. Simultaneous analysis of results was performed using an iterative process adopting the sigmoid function Y = y/1 (dose of toxicant/IC50)slope for dose-response relationships. IC50 (+/- SEM) was estimated (P less than 0.05). An application with phosalone as a toxicant is presented.

Correlations of External Landmarks With Internal Structures of the Temporal Bone.

PubMed

Piromchai, Patorn; Wijewickrema, Sudanthi; Smeds, Henrik; Kennedy, Gregor; O'Leary, Stephen

2015-09-01

The internal anatomy of a temporal bone could be inferred from external landmarks. Mastoid surgery is an important skill that ENT surgeons need to acquire. Surgeons commonly use CT scans as a guide to understanding anatomical variations before surgery. Conversely, in cases where CT scans are not available, or in the temporal bone laboratory where residents are usually not provided with CT scans, it would be beneficial if the internal anatomy of a temporal bone could be inferred from external landmarks. We explored correlations between internal anatomical variations and metrics established to quantify the position of external landmarks that are commonly exposed in the operating room, or the temporal bone laboratory, before commencement of drilling. Mathematical models were developed to predict internal anatomy based on external structures. From an operating room view, the distances between the following external landmarks were observed to have statistically significant correlations with the internal anatomy of a temporal bone: temporal line, external auditory canal, mastoid tip, occipitomastoid suture, and Henle's spine. These structures can be used to infer a low lying dura mater (p = 0.002), an anteriorly located sigmoid sinus (p = 0.006), and a more lateral course of the facial nerve (p < 0.001). In the temporal bone laboratory view, the mastoid tegmen and sigmoid sinus were also regarded as external landmarks. The distances between these two landmarks and the operating view external structures were able to further infer the laterality of the facial nerve (p < 0.001) and a sclerotic mastoid (p < 0.001). Two nonlinear models were developed that predicted the distances between the following internal structures with a high level of accuracy: the distance from the sigmoid sinus to the posterior external auditory canal (p < 0.001) and the diameter of the round window niche (p < 0.001). The prospect of encountering some of the more technically challenging anatomical variants encountered in temporal bone dissection can be inferred from the distance between external landmarks found on the temporal bone. These relationships could be used as a guideline to predict challenges during drilling and choosing appropriate temporal bones for dissection.

Irrigation management of sigmoid colostomy.

PubMed

Jao, S W; Beart, R W; Wendorf, L J; Ilstrup, D M

1985-08-01

Questionnaires were sent to 270 patients who had undergone abdominoperineal resection and sigmoid colostomy at the Mayo Clinic, Rochester, Minn, during the ten years from 1972 to 1982; 223 patients returned their questionnaires with evaluable data. Sixty percent of the patients were continent with irrigation, and 22% were incontinent with irrigation. Eighteen percent had discontinued irrigation for various reasons. The proportion continent was higher in women, younger patients, and previously constipated patients. A poorly constructed colostomy may cause acute angle, parastoma hernia, stomal prolapse, or stenosis and thus be the cause of failure of irrigation.

Rupture of abdominal aortic aneurysm into sigmoid colon: A case report

PubMed Central

Aksoy, Murat; Yanar, Hakan; Taviloglu, Korhan; Ertekin, Cemalettin; Ayalp, Kemal; Yanar, Fatih; Guloglu, Recep; Kurtoglu, Mehmet

2006-01-01

Primary aorto-colic fistula is rarely reported in the literature. Although infrequently encountered, it is an important complication since it is usually fatal unless detected. Primary aorto-colic fistula is a spontaneous rupture of abdominal aortic aneurysm into the lumen of the adjacent colon loop. Here we report a case of primary aorto-colic fistula in a 54-year old male. The fistulated sigmoid colon was repaired by end-to-end anastomosis. Despite inotropic support, the patient died of sepsis and multiorgan failure on the first postoperative day. PMID:17167850

A Novel Higher Order Artificial Neural Networks

NASA Astrophysics Data System (ADS)

Xu, Shuxiang

2010-05-01

In this paper a new Higher Order Neural Network (HONN) model is introduced and applied in several data mining tasks. Data Mining extracts hidden patterns and valuable information from large databases. A hyperbolic tangent function is used as the neuron activation function for the new HONN model. Experiments are conducted to demonstrate the advantages and disadvantages of the new HONN model, when compared with several conventional Artificial Neural Network (ANN) models: Feedforward ANN with the sigmoid activation function; Feedforward ANN with the hyperbolic tangent activation function; and Radial Basis Function (RBF) ANN with the Gaussian activation function. The experimental results seem to suggest that the new HONN holds higher generalization capability as well as abilities in handling missing data.

Development and control of a magnetorheological haptic device for robot assisted surgery.

PubMed

Shokrollahi, Elnaz; Goldenberg, Andrew A; Drake, James M; Eastwood, Kyle W; Kang, Matthew

2017-07-01

A prototype magnetorheological (MR) fluid-based actuator has been designed for tele-robotic surgical applications. This device is capable of generating forces up to 47 N, with input currents ranging from 0 to 1.5 A. We begin by outlining the physical design of the device, and then discuss a novel nonlinear model of the device's behavior. The model was developed using the Hammerstein-Wiener (H-W) nonlinear black-box technique and is intended to accurately capture the hysteresis behavior of the MR-fluid. Several experiments were conducted on the device to collect estimation and validation datasets to construct the model and assess its performance. Different estimating functions were used to construct the model, and their effectiveness is assessed based on goodness-of-fit and final-prediction-error measurements. A sigmoid network was found to have a goodness-of-fit of 95%. The model estimate was then used to tune a PID controller. Two control schemes were proposed to eliminate the hysteresis behavior present in the MR fluid device. One method uses a traditional force feedback control loop and the other is based on measuring the magnetic field using a Hall-effect sensor embedded within the device. The Hall-effect sensor scheme was found to be superior in terms of cost, simplicity and real-time control performance compared to the force control strategy.

From monoscale to multiscale modeling of fatigue crack growth: Stress and energy density factor

NASA Astrophysics Data System (ADS)

Sih, G. C.

2014-01-01

The formalism of the earlier fatigue crack growth models is retained to account for multiscaling of the fatigue process that involves the creation of macrocracks from the accumulation of micro damage. The effects of at least two scales, say micro to macro, must be accounted for. The same data can thus be reinterpreted by the invariancy of the transitional stress intensity factors such that the microcracking and macrocracking data would lie on a straight line. The threshold associated with the sigmoid curve disappears. Scale segmentation is shown to be a necessity for addressing multiscale energy dissipative processes such as fatigue and creep. Path independency and energy release rate are monoscale criteria that can lead to unphysical results, violating the first principles. Application of monoscale failure or fracture criteria to nanomaterials is taking toll at the expense of manufacturing super strength and light materials and structural components. This brief view is offered in the spirit of much needed additional research for the reinforcement of materials by creating nanoscale interfaces with sustainable time in service. The step by step consideraton at the different scales may offer a better understanding of the test data and their limitations with reference to space and time.

Embedding recurrent neural networks into predator-prey models.

PubMed

Moreau, Yves; Louiès, Stephane; Vandewalle, Joos; Brenig, Leon

1999-03-01

We study changes of coordinates that allow the embedding of ordinary differential equations describing continuous-time recurrent neural networks into differential equations describing predator-prey models-also called Lotka-Volterra systems. We transform the equations for the neural network first into quasi-monomial form (Brenig, L. (1988). Complete factorization and analytic solutions of generalized Lotka-Volterra equations. Physics Letters A, 133(7-8), 378-382), where we express the vector field of the dynamical system as a linear combination of products of powers of the variables. In practice, this transformation is possible only if the activation function is the hyperbolic tangent or the logistic sigmoid. From this quasi-monomial form, we can directly transform the system further into Lotka-Volterra equations. The resulting Lotka-Volterra system is of higher dimension than the original system, but the behavior of its first variables is equivalent to the behavior of the original neural network. We expect that this transformation will permit the application of existing techniques for the analysis of Lotka-Volterra systems to recurrent neural networks. Furthermore, our results show that Lotka-Volterra systems are universal approximators of dynamical systems, just as are continuous-time neural networks.

Dynamics in a nonlinear Keynesian good market model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naimzada, Ahmad, E-mail: ahmad.naimzada@unimib.it; Pireddu, Marina, E-mail: marina.pireddu@unimib.it

2014-03-15

In this paper, we show how a rich variety of dynamical behaviors can emerge in the standard Keynesian income-expenditure model when a nonlinearity is introduced, both in the cases with and without endogenous government spending. A specific sigmoidal functional form is used for the adjustment mechanism of income with respect to the excess demand, in order to bound the income variation. With the aid of analytical and numerical tools, we investigate the stability conditions, bifurcations, as well as periodic and chaotic dynamics. Globally, we study multistability phenomena, i.e., the coexistence of different kinds of attractors.

Modelling and Simulation of the Dynamics of the Antigen-Specific T Cell Response Using Variable Structure Control Theory.

PubMed

Anelone, Anet J N; Spurgeon, Sarah K

2016-01-01

Experimental and mathematical studies in immunology have revealed that the dynamics of the programmed T cell response to vigorous infection can be conveniently modelled using a sigmoidal or a discontinuous immune response function. This paper hypothesizes strong synergies between this existing work and the dynamical behaviour of engineering systems with a variable structure control (VSC) law. These findings motivate the interpretation of the immune system as a variable structure control system. It is shown that dynamical properties as well as conditions to analytically assess the transition from health to disease can be developed for the specific T cell response from the theory of variable structure control. In particular, it is shown that the robustness properties of the specific T cell response as observed in experiments can be explained analytically using a VSC perspective. Further, the predictive capacity of the VSC framework to determine the T cell help required to overcome chronic Lymphocytic Choriomeningitis Virus (LCMV) infection is demonstrated. The findings demonstrate that studying the immune system using variable structure control theory provides a new framework for evaluating immunological dynamics and experimental observations. A modelling and simulation tool results with predictive capacity to determine how to modify the immune response to achieve healthy outcomes which may have application in drug development and vaccine design.

A Novel Extreme Learning Machine Classification Model for e-Nose Application Based on the Multiple Kernel Approach

PubMed Central

Jian, Yulin; Huang, Daoyu; Yan, Jia; Lu, Kun; Huang, Ying; Wen, Tailai; Zeng, Tanyue; Zhong, Shijie; Xie, Qilong

2017-01-01

A novel classification model, named the quantum-behaved particle swarm optimization (QPSO)-based weighted multiple kernel extreme learning machine (QWMK-ELM), is proposed in this paper. Experimental validation is carried out with two different electronic nose (e-nose) datasets. Being different from the existing multiple kernel extreme learning machine (MK-ELM) algorithms, the combination coefficients of base kernels are regarded as external parameters of single-hidden layer feedforward neural networks (SLFNs). The combination coefficients of base kernels, the model parameters of each base kernel, and the regularization parameter are optimized by QPSO simultaneously before implementing the kernel extreme learning machine (KELM) with the composite kernel function. Four types of common single kernel functions (Gaussian kernel, polynomial kernel, sigmoid kernel, and wavelet kernel) are utilized to constitute different composite kernel functions. Moreover, the method is also compared with other existing classification methods: extreme learning machine (ELM), kernel extreme learning machine (KELM), k-nearest neighbors (KNN), support vector machine (SVM), multi-layer perceptron (MLP), radical basis function neural network (RBFNN), and probabilistic neural network (PNN). The results have demonstrated that the proposed QWMK-ELM outperforms the aforementioned methods, not only in precision, but also in efficiency for gas classification. PMID:28629202

[Treatment reality with respect to laparoscopic surgery of colonic cancer in Germany].

PubMed

Ptok, H; Gastinger, I; Bruns, C; Lippert, H

2014-07-01

Prospective randomized studies and meta-analyses have shown that laparoscopic resection for colonic cancer is equivalent to open resection with respect to the oncological results and has short-term advantages in the early postoperative outcome. The aim of this study was to investigate whether laparoscopic colonic resection has become established as the standard in routine treatment. Data from the multicenter observational study "Quality assurance colonic cancer (primary tumor)" from the time period from 1 January 2009 to 21 December 2011 were evaluated with respect to the total proportion of laparoscopic colonic cancer resections and tumor localization and specifically for laparoscopic sigmoid colon cancer resections. A comparison between low and high volume clinics (< 30 versus ≥ 30 colonic cancer resections/year) was carried out. Laparoscopic colonic cancer resections were carried out in 12 % versus 21.4 % of low and high volume clinics, respectively (p < 0.001) with a significant increase for low volume clinics (from 8.0 % to 15.6 %, p < 0.001) and a constant proportion in high volume clinics (from 21.7 % to 21.1 %, p = 0.905). For sigmoid colon cancer laparoscopic resection was carried out in 49.7 % versus 47.6 % (p = 0.584). Differences were found between low volume and high volume clinics in the conversion rates (17.3 % versus 6.6 %, p < 0.001), the length of the resected portion (Ø 23.6 cm versus 36.0 cm, p < 0.001) and the lymph node yield (Ø n = 15.7 versus 18.2, p = 0.008). There were no differences between the two groups of clinics regarding postoperative morbidity and mortality. The postoperative morbidity and length of stay were significantly lower for laparoscopic sigmoid resection than for conventional sigmoid resection. The laparoscopic access route for colonic cancer resection is not the standard approach in the participating clinics. The laparoscopic access route has the highest proportion for sigmoid colon resection. The differences in the conversion rates, length of the resected portion and the number of lymph nodes investigated between the low volume and high volume clinics must be viewed critically and must be interpreted in connection with the long-term oncological results.

Sigmoid cancer versus chronic diverticular disease: differentiating features at CT colonography.

PubMed

Lips, Leonie M J; Cremers, Pierre T J; Pickhardt, Perry J; Cremers, Simone E H; Janssen-Heijnen, Maryska L G; de Witte, Marcel T; Simons, Petra C G

2015-04-01

To retrospectively identify morphologic findings at computed tomographic (CT) colonography that are the most reliable in the differentiation of masslike chronic diverticular disease from sigmoid carcinoma in a large patient cohort. This study was approved by the institutional review boards. The need for signed consent was waived for this retrospective study. The cohort consisted of 212 patients (mean age, 68 years; 113 women, 99 men) with focal masslike findings in the sigmoid colon at CT colonography, representing chronic diverticular disease (n = 97) or sigmoid carcinoma (n = 115). CT colonography studies were scored according to presence or absence of potential discriminators by a panel of four readers in consensus. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated, and multivariate analysis was performed. Absence of diverticula in the affected segment showed high NPV and PPV (0.95 and 0.93, respectively). Also, shoulder phenomenon showed a high NPV (0.92) and PPV (0.75). Segment length of 10 cm or less (NPV, 0.85; PPV, 0.61) and destroyed mucosal folds (NPV, 1.00; PPV, 0.62) had a high NPV but a low PPV. Although segments affected by carcinoma often showed straightened and eccentric growth patterns, no thick fascia sign, and more and larger local-regional lymph nodes (all P < .05), NPV was insufficient for discrimination (NPV ≤ 0.66). Combination of absence of diverticula and presence of shouldering showed a high diagnostic certainty (93%). Carcinoma is best differentiated from masslike diverticular disease by the absence of diverticula in the affected segment and the presence of shoulder phenomenon. © RSNA, 2014.

Orthotopic sigmoid vs. ileal neobladders in Japanese patients: a comparative assessment of complications, functional outcomes, and quality of life.

PubMed

Miyake, Hideaki; Furukawa, Junya; Sakai, Iori; Muramaki, Mototsugu; Yamashita, Masuo; Inoue, Taka-Aki; Fujisawa, Masato

2013-10-01

To compare the clinical outcomes of sigmoid and ileal neobladders (NBs) created following radical cystectomy. This study included 90 and 144 Japanese patients undergoing radical cystectomy and orthotopic NB reconstruction with a sigmoid and ileal segment, respectively. Postoperative clinical outcomes between the sigmoid and ileal NB groups (SNBG and INBG) were compared. In this series, 110 early and 51 late complications occurred in 71 and 41 patients, respectively; however, there was no significant difference in the incidence of complications between SNBG and INBG. At 1 year postoperatively, there were no significant differences in the proportion of spontaneous voiders and the continence status between these 2 groups; however, despite the lack of significant differences in the maximal flow rate and voided volume, the post-void residual in SNBG was significantly smaller than that in INBG. Voiding functional outcomes at 5 years postoperatively were also obtained from 28 and 49 in SNBG and INBG, respectively. Although there were no significant changes in the functional outcomes in SNBG, the proportion of spontaneous voiders and post-void residual in INBG at 5 years postoperatively were significantly poorer than those at 1 year postoperatively. Furthermore, the postoperative health-related quality of life assessed by a Short-Form 36 survey did not show any significant differences in all 8 scores between these 2 groups. Both types of NB reconstruction resulted in comparatively satisfactory outcomes; however, the voiding function, particularly that on long-term follow-up, in SNBG appeared to be more favorable than that in INBG. Copyright © 2013 Elsevier Inc. All rights reserved.

Concurrent Angioplasty Balloon Placement for Stent Delivery through Jugular Venous Bulb for Treating Cerebral Venous Sinus Stenosis. Technical Report.

PubMed

Qureshi, Adnan I; Khan, Asif A; Capistrant, Rachel; Qureshi, Mushtaq H; Xie, Kevin; Suri, M Fareed K

2016-10-01

To report upon technique of concurrent placement of angioplasty balloon at the internal jugular vein and sigmoid venous sinus junction to facilitate stent delivery in two patients in whom stent delivery past the jugular bulb was not possible. A 21-year-old woman and a 41-year-old woman with worsening headaches, visual obscuration or diplopia were treated for pseudotumor cerebri associated with transverse venous stenosis. Both patients had undergone primary angioplasty, which resulted in improvement in clinical symptoms followed by the recurrence of symptoms with restenosis at the site of angioplasty. After multiple attempts at stent delivery through jugular venous bulb were unsuccessful, a second guide catheter was placed in the ipsilateral internal jugular vein through contralateral femoral venous approach. A 6 mm × 20 mm (left) or 5 × 15 mm (right) angioplasty balloon was placed across the internal jugular vein and sigmoid sinus junction and partially inflated until the inflation and relative straightening of the junction was observed. In both patients, the internal jugular vein and sigmoid sinus junction was successfully traversed by the stent delivery system in a parallel alignment to inflated balloon. Balloon mounted stent was deployed at the site of restenosis with near complete resolution of lumen narrowing delivery and improvement in clinical symptoms. We report a technique for realignment and diameter change with concurrent placement and partial inflation of angioplasty balloon at the jugular venous bulb to facilitate stent delivery into the sigmoid and transverse venous sinuses in circumstances where multiple attempts at stent delivery are unsuccessful.

ADENOCARCINOMA AND TUBERCULOSIS OF THE SIGMOID COLON AND FALLOPIAN TUBE--A RARE ASSOCIATION. A CASE REPORT AND REVIEW OF THE LITERATURE.

PubMed

Ionescu, Lidia; Dănilă, R; Ciobanu, Delia; Ciortescu, Irina; Livadariu, Roxana; Timofte, D

2016-01-01

Association of adenocarcinoma and tuberculosis (TB) of the sigmoid colon is a rare clinical condition even in an endemic country as Romania, with challenging diagnosis and treatment. Case report. We present the case of a 57-year-old female patient who was admitted on emergency basis for a diagnosis of obstructive sigmoid adenocarcinoma. The patient was operated on and it an obstructive sigmoid tumor with serosal invasion, adherent (invading) to the body of uterus and left adnexa and urinary bladder serosa, no liver or peritoneal metastases. A sigmoidectomy was performed "en bloc" with subtotal hysterectomy, left adnexectomy and extramucosal cistectomy. The histopathological exam showed a moderately differentiated, ulcerated adenocarcinoma, widely infiltrating the colon wall invading the myometrium. Ziehl Neelsen (ZN) stain identified the presence of metachromatic bacillary structures in the colonic wall, lymph nodes and adnexal areas. Postoperative course was uneventful and the patient was discharged 10 days postoperatively in good clinical condition. After one year when the patient completed the full course of anti-tubercular drugs, a thorough work-up was performed. Colonoscopy, CT of the thorax, abdomen, pelvis showed no signs of recurrence while tumoral marker CEA (1.62 ng/ml - n<3.4) and QFT (Quantiferon-TB Gold) test were within normal range. Discussion and conclusion. Although digestive tuberculosis is included in differential diagnosis for those patients presenting abdominal pain or obstructive digestive symptoms in endemic regions, in this case the absence of TB infection criteria and positive endoscopic biopsy for colonic adenocarcinoma did not allow a complete pre- or perioperative diagnosis.

Adjuvant breast cancer therapy: current status and future strategies--growth kinetics and the improved drug therapy of breast cancer.

PubMed

Norton, L

1999-02-01

It is well-established that the adjuvant treatment of breast cancer is effective in prolonging both disease-free and overall survival. The pressing questions are how to improve on existing treatment, whether new agents should be incorporated into adjuvant regimens, and, if so, how they should best be utilized. The application of log-kill principles to the sigmoid growth curve characteristic of human cancers suggests that the chances of eradicating tumor will be increased by dose-dense schedules. If the tumor is composed of several cell lines with different sensitivities, the optimum therapy is likely to consist of several drugs given in sequence at a good dose and on a dense schedule. Such sequential chemotherapy, rather than the use of drugs given in combination at longer intervals, should maximize log-kill at the same time as minimizing tumor regrowth. There is now evidence that the actions of chemotherapy may involve Ras, tyrosine kinases (epidermal growth factor receptor, HER2), TC21, or similar molecules. This concept may provide important clues for optimizing the clinical applications of drug therapy and for designing new therapeutic approaches. It might also explain the reason why dose density may be more effective than other schedules of administration. New blood vessel formation is an obligatory step in the establishment of a tumor in its sigmoid growth course and there is evidence that taxanes adversely affect this process. Major practical advances in the curative drug therapy of cancer should follow the demonstration of better ways to maximize cell kill, the development of predictive in vitro methods of selecting active agents, the discovery of techniques to minimize both drug resistance and host-cell toxicity, and the improved understanding of cancer-stromal interactions and their therapeutic perturbation.

Continental-Scale View of Bankfull Width Versus Drainage Area Relationship

NASA Astrophysics Data System (ADS)

Wilkerson, G. V.

2012-12-01

While recognizing that there are multiple variables that influence bankfull channel width (Wbf), this study explores the relationship between Wbf and drainage area (Ada) across a range of geologic, terrestrial, climatic, and botanical environments. The study aims to develop a foundational model that will facilitate developing a comprehensive multivariate model for predicting channel width. Data for this study was compiled from independent regional curve studies (i.e., studies in which Wbf vs. Ada relationships are developed). The data represent 1,018 sites that span 12 states in the continental U.S. The channels are alluvial and are such that 1 m ≤ Wbf ≤ 110 m and 0.50 km2 ≤ Ada ≤ 22,000 km2. For developing regional curves, the Wbf vs. Ada relationship is generally assumed to be log-linear. Also, past studies have indicated that the Wbf vs. Ada relationship differs for small basins (i.e., 10 to 100 km2) and large basins due to the effects of vegetation. Linear and nonlinear (i.e., sigmoidal) models were considered for this study. The best model relates ln(Wbf ) and ln(Ada) using a three-piece linear model (Figure 1). The value of dWbf /dAda is significantly greater (p < 0.001) for mid-size basins (5 km2 ≤ Ada ≤ 350 km2) than either small or large basins. The noted change in dWbf /dAda is likely in response to vegetation. Also, the change in dWbf /dAda is so abrupt that the three-piece linear model, fits the data better than any of the sigmoidal functions explored in this study. For every model evaluated in this study, the residuals were bi-modal (Figure 2). For the residuals to begin converging on a normal distribution, at least one other factor (probably precipitation) needs to be included in the model.

SU-E-T-310: Dosimetric Comparison of Tandem and Ovoid (TO) Vs. Tandem and Ring (TR) Applicators in High-Dose Rate (HDR) Brachytherapy (BT) for the Treatment of Locally-Advanced Cervical-Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuo, L; Viswanathan, A; Damato, A

2015-06-15

Purpose: To investigate the dosimetric differences associated with the use of TO or TR applicators for cervical-cancer HDR BT. Methods: The records of all cervical-cancer patients treated with image-guided HDR BT in 2013 were reviewed. Image-based planning based on isodose line and DVH metrics inspections was performed following the GEC-ESTRO recommendations. CTV volume, CTV D90, and rectum, bladder and sigmoid D2cc were collected as % of the prescription dose (80Gy EQD2). Patients receiving both TO and TR were identified and plans were compared (paired analysis). A Student T-test was used to evaluate statistical significance (p ≤ 0.05). Results: Twenty-eight patientsmore » were identified (20 TR only, 4 TO only, 4 TO and TR), associated with 116 plans (109 TR, 7 TO). Overall metrics: CTV volume, 26.5±10.4 cm3 (TR) and 39.1±14.0 cm3 (TO, p < 0.01); CTV D90, 126±28% (TR) and 110±15% (TO, p = 0.15); rectum D2cc, 56±11% (TR) and 58±19% (TO, p = 0.91); bladder D2cc, 74±20% (TR) and 88±19% (TO, p = 0.09); sigmoid D2cc, 52±17% (TR) and 49±20% (TO, p = 0.63). The paired analysis results were: CTV volume, 37.3±11.9 cm3 (TR) and 51.0±23.1 cm3 (TO, p = 0.23); CTV D90, 111±12% (TR) and 101±17% (TO, p = 0.50); rectum D2cc, 56±12% (TR) and 53±16% (TO, p = 0.71); bladder D2cc, 73±14% (TR) and 90±20% (TO, p = 0.22); sigmoid D2cc, 59±10% (TR) and 59±22% (TO, p = 0.98). Conclusion: TR and TO were both used with good dosimetric results. TO were used for patients with larger CTV volumes than TR, although paired analysis suggest that tissue distortion and contouring bias may partially explain this Result. CTV D90 on average > 80 Gy EQD2 were achieved in both groups despite the different CTV volume. Higher bladder D2cc for TO than TR was observed.« less

Can MRI-only replace MRI-CT planning with a titanium tandem and ovoid applicator?

PubMed

Harkenrider, Matthew M; Patel, Rakesh; Surucu, Murat; Chinsky, Bonnie; Mysz, Michael L; Wood, Abbie; Ryan, Kelly; Shea, Steven M; Small, William; Roeske, John C

2018-06-23

To evaluate dosimetric differences between MRI-only and MRI-CT planning with a titanium tandem and ovoid applicator to determine if all imaging and planning goals can be achieved with MRI only. We evaluated 10 patients who underwent MRI-CT-based cervical brachytherapy with a titanium tandem and ovoid applicator. High-risk clinical target volume and organs at risk were contoured on the 3D T2 MRI, which were transferred to the co-registered CT, where the applicator was identified. Retrospectively, three planners independently delineated the applicator on the axial 3D T2 MRI while blinded to the CT. Identical dwell position times in the delivered plan were loaded. Dose-volume histogram parameters were compared to the previously delivered MRI-CT plan. There were no significant differences in dose to D 90 or D 98 of the high-risk clinical target volume with MRI vs. MRI-CT planning. MRI vs. MRI-CT planning resulted in mean D 0.1cc bladder of 8.8 ± 3.4 Gy vs. 8.5 ± 3.2 Gy (p = 0.29) and D 2cc bladder of 6.2 ± 1.4 Gy vs. 6.0 ± 1.4 Gy (p = 0.33), respectively. Mean D 0.1cc rectum was 5.7 ± 1.2 Gy vs. 5.3 ± 1.2 Gy (p = 0.03) and D 2cc rectum 4.0 ± 0.8 Gy vs. 4.2 ± 1.0 Gy (p = 0.18), respectively. Mean D 0.1cc sigmoid was 5.2 ± 1.3 Gy vs. 5.4 ± 1.6 Gy (p = 0.23) and D 2cc sigmoid 3.9 ± 1.0 Gy vs. 4.0 ± 1.1 Gy (p = 0.18), respectively. There were no clinically significant dosimetric differences between the MRI and MRI-CT plans. This study demonstrates that cervical brachytherapy with a titanium applicator can be planned with MRI alone, which is now our clinical standard. Copyright © 2018. Published by Elsevier Inc.

[Follow-up and dietary advice after sigmoid diverticulitis].

PubMed

Barret, Maximilien; Abbes, Leila; Zinzindohoué, Franck

2013-06-01

Currently published data do not demonstrate the benefit of any medical treatment in the prevention of the onset or the recurrence of colonic diverticular disease. No specific diet can be recommended to patients with colonic diverticula for the prevention of diverticular disease. Non steroidal anti-inflammatory drugs as well as corticosteroids should be used cautiously in patients with diverticular disease since they induce a higher rate of complications, especially diverticular haemorrhage and severe sigmoid diverticulitis. In patients over 50 years old, or if a sigmoidectomy is needed, physicians should perform a colonoscopy in order to rule out colonic polyps or neoplasm.

[Successful Removal of Hard Sigmoid Fecaloma Using Endoscopic Cola Injection].

PubMed

Lee, Jong Jin; Kim, Jeong Wook

2015-07-01

Colorectal fecaloma is hardening of feces into lumps of varying size that is much harder in consistency than a fecal impaction. Complications of colorectal fecaloma include ulceration, bleeding, perforation and obstruction of the colon. Most fecalomas are successfully removed by conservative treatment with laxatives, enemas and rectal evacuation to relieve fecal impaction. When conservative treatments have failed, a surgical intervention may be needed. Herein, we report a case of 4.7 cm sized sigmoid fecaloma showing no response to conservative treatments that was successfully removed by endoscopic fragmentation with Coca-Cola injection instead of surgery.

HOOKED FLARE RIBBONS AND FLUX-ROPE-RELATED QSL FOOTPRINTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Jie; Li, Hui; Gilchrist, Stuart A.

2016-05-20

We studied the magnetic topology of active region 12158 on 2014 September 10 and compared it with the observations before and early in the flare that begins at 17:21 UT (SOL2014-09-10T17:45:00). Our results show that the sigmoidal structure and flare ribbons of this active region observed by the Solar Dynamics Observatory /Atmospheric Imaging Assembly can be well reproduced from a Grad–Rubin nonlinear force-free field extrapolation method. Various inverse-S- and inverse-J-shaped magnetic field lines, which surround a coronal flux rope, coincide with the sigmoid as observed in different extreme-ultraviolet wavelengths, including its multithreaded curved ends. Also, the observed distribution of surfacemore » currents in the magnetic polarity where it was not prescribed is well reproduced. This validates our numerical implementation and setup of the Grad–Rubin method. The modeled double inverse-J-shaped quasi-separatrix layer (QSL) footprints match the observed flare ribbons during the rising phase of the flare, including their hooked parts. The spiral-like shape of the latter may be related to a complex pre-eruptive flux rope with more than one turn of twist, as obtained in the model. These ribbon-associated flux-rope QSL footprints are consistent with the new standard flare model in 3D, with the presence of a hyperbolic flux tube located below an inverse-teardrop-shaped coronal QSL. This is a new step forward forecasting the locations of reconnection and ribbons in solar flares and the geometrical properties of eruptive flux ropes.« less

Neural networks and applications tutorial

NASA Astrophysics Data System (ADS)

Guyon, I.

1991-09-01

The importance of neural networks has grown dramatically during this decade. While only a few years ago they were primarily of academic interest, now dozens of companies and many universities are investigating the potential use of these systems and products are beginning to appear. The idea of building a machine whose architecture is inspired by that of the brain has roots which go far back in history. Nowadays, technological advances of computers and the availability of custom integrated circuits, permit simulations of hundreds or even thousands of neurons. In conjunction, the growing interest in learning machines, non-linear dynamics and parallel computation spurred renewed attention in artificial neural networks. Many tentative applications have been proposed, including decision systems (associative memories, classifiers, data compressors and optimizers), or parametric models for signal processing purposes (system identification, automatic control, noise canceling, etc.). While they do not always outperform standard methods, neural network approaches are already used in some real world applications for pattern recognition and signal processing tasks. The tutorial is divided into six lectures, that where presented at the Third Graduate Summer Course on Computational Physics (September 3-7, 1990) on Parallel Architectures and Applications, organized by the European Physical Society: (1) Introduction: machine learning and biological computation. (2) Adaptive artificial neurons (perceptron, ADALINE, sigmoid units, etc.): learning rules and implementations. (3) Neural network systems: architectures, learning algorithms. (4) Applications: pattern recognition, signal processing, etc. (5) Elements of learning theory: how to build networks which generalize. (6) A case study: a neural network for on-line recognition of handwritten alphanumeric characters.

Estimating non-isothermal bacterial growth in foods from isothermal experimental data.

PubMed

Corradini, M G; Peleg, M

2005-01-01

To develop a mathematical method to estimate non-isothermal microbial growth curves in foods from experiments performed under isothermal conditions and demonstrate the method's applicability with published growth data. Published isothermal growth curves of Pseudomonas spp. in refrigerated fish at 0-8 degrees C and Escherichia coli 1952 in a nutritional broth at 27.6-36 degrees C were fitted with two different three-parameter 'primary models' and the temperature dependence of their parameters was fitted by ad hoc empirical 'secondary models'. These were used to generate non-isothermal growth curves by solving, numerically, a differential equation derived on the premise that the momentary non-isothermal growth rate is the isothermal rate at the momentary temperature, at a time that corresponds to the momentary growth level of the population. The predicted non-isothermal growth curves were in agreement with the reported experimental ones and, as expected, the quality of the predictions did not depend on the 'primary model' chosen for the calculation. A common type of sigmoid growth curve can be adequately described by three-parameter 'primary models'. At least in the two systems examined, these could be used to predict growth patterns under a variety of continuous and discontinuous non-isothermal temperature profiles. The described mathematical method whenever validated experimentally will enable the simulation of the microbial quality of stored and transported foods under a large variety of existing or contemplated commercial temperature histories.

The application of percutaneous endoscopic colostomy to the management of obstructed defecation.

PubMed

Heriot, A G; Tilney, H S; Simson, J N L

2002-05-01

We describe the case of a 52-year woman with a 17-year history of obstructed defecation in whom all other standard treatments had failed and the patient had refused a colostomy. Her symptoms were controlled by percutaneous endoscopic colostomy with antegrade colonic irrigation. A percutaneous endoscopic colostomy tube was placed in the sigmoid colon endoscopically using a colonoscope and the patient irrigated two liters of water through the percutaneous endoscopic colostomy twice each day and was able to successfully evacuate her rectum without excess straining or discomfort. Percutaneous endoscopic colostomy is an alternative option to colostomy in the management of obstructed defecation.

Valuation of opportunity costs by rats working for rewarding electrical brain stimulation.

PubMed

Solomon, Rebecca Brana; Conover, Kent; Shizgal, Peter

2017-01-01

Pursuit of one goal typically precludes simultaneous pursuit of another. Thus, each exclusive activity entails an "opportunity cost:" the forgone benefits from the next-best activity eschewed. The present experiment estimates, in laboratory rats, the function that maps objective opportunity costs into subjective ones. In an operant chamber, rewarding electrical brain stimulation was delivered when the cumulative time a lever had been depressed reached a criterion duration. The value of the activities forgone during this duration is the opportunity cost of the electrical reward. We determined which of four functions best describes how objective opportunity costs, expressed as the required duration of lever depression, are translated into their subjective equivalents. The simplest account is the identity function, which equates subjective and objective opportunity costs. A variant of this function called the "sigmoidal-slope function," converges on the identity function at longer durations but deviates from it at shorter durations. The sigmoidal-slope function has the form of a hockey stick. The flat "blade" denotes a range over which opportunity costs are subjectively equivalent; these durations are too short to allow substitution of more beneficial activities. The blade extends into an upward-curving portion over which costs become discriminable and finally into the straight "handle," over which objective and subjective costs match. The two remaining functions are based on hyperbolic and exponential temporal discounting, respectively. The results are best described by the sigmoidal-slope function. That this is so suggests that different principles of intertemporal choice are involved in the evaluation of time spent working for a reward or waiting for its delivery. The subjective opportunity-cost function plays a key role in the evaluation and selection of goals. An accurate description of its form and parameters is essential to successful modeling and prediction of instrumental performance and reward-related decision making.

Meat, meat cooking methods and preservation, and risk for colorectal adenoma.

PubMed

Sinha, Rashmi; Peters, Ulrike; Cross, Amanda J; Kulldorff, Martin; Weissfeld, Joel L; Pinsky, Paul F; Rothman, Nathaniel; Hayes, Richard B

2005-09-01

Cooking meat at high temperatures produces heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs). Processed meats contain N-nitroso compounds. Meat intake may increase cancer risk as HCAs, PAHs, and N-nitroso compounds are carcinogenic in animal models. We investigated meat, processed meat, HCAs, and the PAH benzo(a)pyrene and the risk of colorectal adenoma in 3,696 left-sided (descending and sigmoid colon and rectum) adenoma cases and 34,817 endoscopy-negative controls. Dietary intake was assessed using a 137-item food frequency questionnaire, with additional questions on meats and meat cooking practices. The questionnaire was linked to a previously developed database to determine exposure to HCAs and PAHs. Intake of red meat, with known doneness/cooking methods, was associated with an increased risk of adenoma in the descending and sigmoid colon [odds ratio (OR), 1.26; 95% confidence interval (95% CI), 1.05-1.50 comparing extreme quintiles of intake] but not rectal adenoma. Well-done red meat was associated with increased risk of colorectal adenoma (OR, 1.21; 95% CI, 1.06-1.37). Increased risks for adenoma of the descending colon and sigmoid colon were observed for the two HCAs: 2-amino-3,8-dimethylimidazo[4,5]quinoxaline and 2-amino-1-methyl-6-phenylimidazo[4,5]pyridine (OR, 1.18; 95% CI, 1.01-1.38 and OR, 1.17, 95% CI, 1.01-1.35, respectively) as well as benzo(a)pyrene (OR, 1.18; 95% CI, 1.02-1.35). Greater intake of bacon and sausage was associated with increased colorectal adenoma risk (OR, 1.14; 95% CI, 1.00-1.30); however, total intake of processed meat was not (OR, 1.04; 95% CI, 0.90-1.19). Our study of screening-detected colorectal adenomas shows that red meat and meat cooked at high temperatures are associated with an increased risk of colorectal adenoma.

Minus-Lens–Stimulated Accommodative Amplitude Decreases Sigmoidally with Age: A Study of Objectively Measured Accommodative Amplitudes from Age 3

PubMed Central

Anderson, Heather A.; Hentz, Gloria; Glasser, Adrian; Stuebing, Karla K.; Manny, Ruth E.

2009-01-01

Purpose Guidelines for predicting accommodative amplitude by age are often based on subjective push-up test data that overestimate the accommodative response. Studies in which objective measurements were used have defined expected amplitudes for adults, but expected amplitudes for children remain unknown. In this study, objective methods were used to measure accommodative amplitude in a wide age range of individuals, to define the relationship of amplitude and age from age 3. Methods Accommodative responses were measured in 140 subjects aged 3 to 40 years. Measurements were taken with the Grand Seiko autorefractor (RyuSyo Industrial Co., Ltd., Kagawa, Japan) as the subjects viewed a high-contrast target at 33 cm through minus lenses of increasing power until the responses showed no further increase in accommodation. Results The maximum accommodative amplitude of each subject was plotted by age, and a curvilinear function fit to the data: y = 7.33 − 0.0035(age − 3)2 (P < 0.001). Tangent analysis of the fit indicated that the accommodative amplitude remained relatively stable until age 20. Data from this study were then pooled with objective amplitudes from previous studies of adults up to age 70. A sigmoidal function was fit to the data: y = 7.083/(1 + e[0.2031(age-36.2)−0.6109]) (P < 0.001). The sigmoidal function indicated relatively stable amplitudes below age 20 years, a rapid linear decline between 20 and 50 years, and a taper to 0 beyond 50 years. Conclusions These data indicate that accommodative amplitude decreases in a curvilinear manner from 3 to 40 years. When combined with data from previous studies, a sigmoidal function describes the overall trend throughout life with the biggest decrease occurring between 20 and 50 years. PMID:18326693

Sigmoid stricture associated with diverticular disease should be an indication for elective surgery with lymph node clearance.

PubMed

Venara, A; Toqué, L; Barbieux, J; Cesbron, E; Ridereau-Zins, C; Lermite, E; Hamy, A

2015-09-01

The literature concerning stricture secondary to diverticulitis is poor. Stricture in this setting should be an indication for surgery because (a) of the potential risk of cancer and (b) morbidity is not increased compared to other indications for colectomy. The goal of this report is to study the post-surgical morbidity and the quality of life in patients after sigmoidectomy for sigmoid stricture associated with diverticular disease. This is a monocenter retrospective observational study including patients with a preoperative diagnosis of sigmoid stricture associated with diverticular disease undergoing operation between Jan 1, 2007 and Dec 31, 2013. The GastroIntestinal Quality of Life Index was used to assess patient satisfaction. Sixteen patients were included of which nine were female. Median age was 69.5 (46-84) and the median body mass index was 23.55kg/m(2) (17.2-28.4). Elective sigmoidectomy was performed in all 16 patients. Overall, complications occurred in five patients (31.2%) (4 minor complications and 1 major complication according to the Dindo and Clavien Classification); none resulted in death. Pathology identified two adenocarcinomas (12.5%). The mean GastroIntestinal Quality of Life Index was 122 (67-144) and 10/11 patients were satisfied with their surgical intervention. Sigmoid stricture prevents endoscopic exploration of the entire colon and thus it may prove difficult to rule out a malignancy. Surgery does not impair the quality of life since morbidity is similar to other indications for sigmoidectomy. For these reasons, we recommend that stricture associated with diverticular disease should be an indication for sigmoidectomy including lymph node clearance. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Colonic smooth muscle responses in patients with diverticular disease of the colon: effect of the NK2 receptor antagonist SR48968.

PubMed

Maselli, M A; Piepoli, A L; Guerra, V; Caruso, M L; Pezzolla, F; Lorusso, D; Demma, I; De Ponti, F

2004-05-01

Little is known about the pathophysiology of diverticular disease. To compare passive and active stress and the response to carbachol of colonic smooth muscle specimens from patients with diverticular disease and patients with colon cancer. The effect of the NK2 receptor antagonist, SR48968, on electrically evoked contractions of circular muscle was also investigated. Sigmoid colon segments were obtained from 16 patients (51-83 years) undergoing elective sigmoid resection for diverticular disease and 39 patients (50-88 years) undergoing left hemicolectomy for non-obstructive sigmoid colon cancer. Isometric tension was measured on circular or longitudinal taenial muscle. Strips were stretched gradually to Lo (length allowing the development of optimal active tension with carbachol) and were also exposed to increasing carbachol concentrations. The effects of atropine, tetrodotoxin and SR48968 on electrically evoked (supramaximal strength, 0.3 ms, 0.1-10 Hz) contractions of circular strips from 8 patients with diverticular disease and 19 patients with colon cancer were also studied. Both passive and active stress in circular muscle strips obtained from patients with diverticular disease was higher than in patients with colon cancer (P < 0.05). Electrically evoked contractions were significantly reduced by atropine in all preparations and were virtually suppressed by combined SR48968 and atropine. Tetrodotoxin suppressed electrically evoked contractions only in patients with colon cancer, whereas a tetrodotoxin-resistant component was identified in patients with diverticular disease. The changes in both passive and active stress in specimens from patients with diverticular disease may reflect circular smooth muscle dysfunction. Acetylcholine and tachykinins are the main excitatory neurotransmitters mediating electrically evoked contractions in human sigmoid colon circular muscle.

Persistence and storage of activity patterns in spiking recurrent cortical networks: modulation of sigmoid signals by after-hyperpolarization currents and acetylcholine

PubMed Central

Palma, Jesse; Grossberg, Stephen; Versace, Massimiliano

2012-01-01

Many cortical networks contain recurrent architectures that transform input patterns before storing them in short-term memory (STM). Theorems in the 1970's showed how feedback signal functions in rate-based recurrent on-center off-surround networks control this process. A sigmoid signal function induces a quenching threshold below which inputs are suppressed as noise and above which they are contrast-enhanced before pattern storage. This article describes how changes in feedback signaling, neuromodulation, and recurrent connectivity may alter pattern processing in recurrent on-center off-surround networks of spiking neurons. In spiking neurons, fast, medium, and slow after-hyperpolarization (AHP) currents control sigmoid signal threshold and slope. Modulation of AHP currents by acetylcholine (ACh) can change sigmoid shape and, with it, network dynamics. For example, decreasing signal function threshold and increasing slope can lengthen the persistence of a partially contrast-enhanced pattern, increase the number of active cells stored in STM, or, if connectivity is distance-dependent, cause cell activities to cluster. These results clarify how cholinergic modulation by the basal forebrain may alter the vigilance of category learning circuits, and thus their sensitivity to predictive mismatches, thereby controlling whether learned categories code concrete or abstract features, as predicted by Adaptive Resonance Theory. The analysis includes global, distance-dependent, and interneuron-mediated circuits. With an appropriate degree of recurrent excitation and inhibition, spiking networks maintain a partially contrast-enhanced pattern for 800 ms or longer after stimuli offset, then resolve to no stored pattern, or to winner-take-all (WTA) stored patterns with one or multiple winners. Strengthening inhibition prolongs a partially contrast-enhanced pattern by slowing the transition to stability, while strengthening excitation causes more winners when the network stabilizes. PMID:22754524

Phenotypic homogeneity with minor deviance in osmotic fragility of Sahel goat erythrocytes in non-ionic sucrose media during various physiologic states.

PubMed

Igbokwe, Nanacha Afifi; Igbokwe, Ikechukwu Onyebuchi

2016-11-01

Erythrocyte swelling in non-ionic sucrose media and the subsequent osmotic lysis are influenced by mechanisms of regulatory volume adjustment and osmotic water permeability. Kinetics of transmembrane water and ion fluxes in varied physiologic states may determine the phenotype of erythrocyte osmotic fragility (EOF) and affect estimates of EOF. Effects of sex, age, late pregnancy (third trimester) and lactation on the haemolysis of Sahel goat erythrocytes incubated in a series of hyposmotic non-ionic sucrose media were investigated. The fragiligram was sigmoidal in 72 (97%) out of 74 goats. Two male (3%) goats with low and high extreme median erythrocyte fragilities (MEF), had non-sigmoidal curves. The mean fragilities at osmolarities of 30-300 mosmol/L of sucrose and the mean osmolarities responsible for 10%-90% haemolysis (CH10-CH90) were not significantly different between males and non-pregnant dry (NPD) females, amongst the age groups and between pregnant or lactating and NPD female goats. The MEF (CH50) of the goats were at osmolarities of 126-252 mosmol/L (median of data: 171 mosmol/L) with a mean of 175.24±16.20 mosmol/L. Therefore, phenotypic homogeneity of EOF occurred with minor deviance, since EOF variables were not differentiated by sex, age, late pregnancy or lactation. Physiologic states of the goat did not affect EOF phenotype in non-ionic sucrose media. Sigmoidal fragility phenotype seemed to be homogeneously conserved by osmoregulatory mechanisms not partitioned by sex, age, late pregnancy or lactation, but a minor non-sigmoidal curve might have occurred due to altered erythrocyte osmotic behaviour that would require further investigation.

Incomplete Neutralization and Deviation from Sigmoidal Neutralization Curves for HIV Broadly Neutralizing Monoclonal Antibodies

PubMed Central

McCoy, Laura E.; Falkowska, Emilia; Doores, Katie J.; Le, Khoa; Sok, Devin; van Gils, Marit J.; Euler, Zelda; Burger, Judith A.; Seaman, Michael S.; Sanders, Rogier W.; Schuitemaker, Hanneke; Poignard, Pascal; Wrin, Terri; Burton, Dennis R.

2015-01-01

The broadly neutralizing HIV monoclonal antibodies (bnMAbs) PG9, PG16, PGT151, and PGT152 have been shown earlier to occasionally display an unusual virus neutralization profile with a non-sigmoidal slope and a plateau at <100% neutralization. In the current study, we were interested in determining the extent of non-sigmoidal slopes and plateaus at <100% for HIV bnMAbs more generally. Using both a 278 panel of pseudoviruses in a CD4 T-cell (U87.CCR5.CXCR4) assay and a panel of 117 viruses in the TZM-bl assay, we found that bnMAbs targeting many neutralizing epitopes of the spike had neutralization profiles for at least one virus that plateaued at <90%. Across both panels the bnMAbs targeting the V2 apex of Env and gp41 were most likely to show neutralization curves that plateaued <100%. Conversely, bnMAbs targeting the high-mannose patch epitopes were less likely to show such behavior. Two CD4 binding site (CD4bs) Abs also showed this behavior relatively infrequently. The phenomenon of incomplete neutralization was also observed in a large peripheral blood mononuclear cells (PBMC)-grown molecular virus clone panel derived from patient viral swarms. In addition, five bnMAbs were compared against an 18-virus panel of molecular clones produced in 293T cells and PBMCs and assayed in TZM-bl cells. Examples of plateaus <90% were seen with both types of virus production with no consistent patterns observed. In conclusion, incomplete neutralization and non-sigmoidal neutralization curves are possible for all HIV bnMAbs against a wide range of viruses produced and assayed in both cell lines and primary cells with implications for the use of antibodies in therapy and as tools for vaccine design. PMID:26267277

Incomplete Neutralization and Deviation from Sigmoidal Neutralization Curves for HIV Broadly Neutralizing Monoclonal Antibodies.

PubMed

McCoy, Laura E; Falkowska, Emilia; Doores, Katie J; Le, Khoa; Sok, Devin; van Gils, Marit J; Euler, Zelda; Burger, Judith A; Seaman, Michael S; Sanders, Rogier W; Schuitemaker, Hanneke; Poignard, Pascal; Wrin, Terri; Burton, Dennis R

2015-08-01

The broadly neutralizing HIV monoclonal antibodies (bnMAbs) PG9, PG16, PGT151, and PGT152 have been shown earlier to occasionally display an unusual virus neutralization profile with a non-sigmoidal slope and a plateau at <100% neutralization. In the current study, we were interested in determining the extent of non-sigmoidal slopes and plateaus at <100% for HIV bnMAbs more generally. Using both a 278 panel of pseudoviruses in a CD4 T-cell (U87.CCR5.CXCR4) assay and a panel of 117 viruses in the TZM-bl assay, we found that bnMAbs targeting many neutralizing epitopes of the spike had neutralization profiles for at least one virus that plateaued at <90%. Across both panels the bnMAbs targeting the V2 apex of Env and gp41 were most likely to show neutralization curves that plateaued <100%. Conversely, bnMAbs targeting the high-mannose patch epitopes were less likely to show such behavior. Two CD4 binding site (CD4bs) Abs also showed this behavior relatively infrequently. The phenomenon of incomplete neutralization was also observed in a large peripheral blood mononuclear cells (PBMC)-grown molecular virus clone panel derived from patient viral swarms. In addition, five bnMAbs were compared against an 18-virus panel of molecular clones produced in 293T cells and PBMCs and assayed in TZM-bl cells. Examples of plateaus <90% were seen with both types of virus production with no consistent patterns observed. In conclusion, incomplete neutralization and non-sigmoidal neutralization curves are possible for all HIV bnMAbs against a wide range of viruses produced and assayed in both cell lines and primary cells with implications for the use of antibodies in therapy and as tools for vaccine design.

The relationship between movement speed and duration during soccer matches.

PubMed

Roecker, Kai; Mahler, Hubert; Heyde, Christian; Röll, Mareike; Gollhofer, Albert

2017-01-01

The relationship between the time duration of movement (t(dur)) and related maximum possible power output has been studied and modeled under many conditions. Inspired by the so-called power profiles known for discontinuous endurance sports like cycling, and the critical power concept of Monod and Scherrer, the aim of this study was to evaluate the numerical characteristics of the function between maximum horizontal movement velocity (HSpeed) and t(dur) in soccer. To evaluate this relationship, GPS data from 38 healthy soccer players and 82 game participations (≥30 min active playtime) were used to select maximum HSpeed for 21 distinct t(dur) values (between 0.3 s and 2,700 s) based on moving medians with an incremental t(dur) window-size. As a result, the relationship between HSpeed and Log(t(dur)) appeared reproducibly as a sigmoidal decay function, and could be fitted to a five-parameter equation with upper and lower asymptotes, and an inflection point, power and decrease rate. Thus, the first three parameters described individual characteristics if evaluated using mixed-model analysis. This study shows for the first time the general numerical relationship between t(dur) and HSpeed in soccer games. In contrast to former descriptions that have evaluated speed against power, HSpeed against t(dur) always yields a sigmoidal shape with a new upper asymptote. The evaluated curve fit potentially describes the maximum moving speed of individual players during the game, and allows for concise interpretations of the functional state of team sports athletes.

The relationship between movement speed and duration during soccer matches

PubMed Central

Mahler, Hubert; Heyde, Christian; Röll, Mareike; Gollhofer, Albert

2017-01-01

The relationship between the time duration of movement (t(dur)) and related maximum possible power output has been studied and modeled under many conditions. Inspired by the so-called power profiles known for discontinuous endurance sports like cycling, and the critical power concept of Monod and Scherrer, the aim of this study was to evaluate the numerical characteristics of the function between maximum horizontal movement velocity (HSpeed) and t(dur) in soccer. To evaluate this relationship, GPS data from 38 healthy soccer players and 82 game participations (≥30 min active playtime) were used to select maximum HSpeed for 21 distinct t(dur) values (between 0.3 s and 2,700 s) based on moving medians with an incremental t(dur) window-size. As a result, the relationship between HSpeed and Log(t(dur)) appeared reproducibly as a sigmoidal decay function, and could be fitted to a five-parameter equation with upper and lower asymptotes, and an inflection point, power and decrease rate. Thus, the first three parameters described individual characteristics if evaluated using mixed-model analysis. This study shows for the first time the general numerical relationship between t(dur) and HSpeed in soccer games. In contrast to former descriptions that have evaluated speed against power, HSpeed against t(dur) always yields a sigmoidal shape with a new upper asymptote. The evaluated curve fit potentially describes the maximum moving speed of individual players during the game, and allows for concise interpretations of the functional state of team sports athletes. PMID:28742832

APPLICATION OF NEURAL NETWORK ALGORITHMS FOR BPM LINEARIZATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Musson, John C.; Seaton, Chad; Spata, Mike F.

2012-11-01

Stripline BPM sensors contain inherent non-linearities, as a result of field distortions from the pickup elements. Many methods have been devised to facilitate corrections, often employing polynomial fitting. The cost of computation makes real-time correction difficult, particulalry when integer math is utilized. The application of neural-network technology, particularly the multi-layer perceptron algorithm, is proposed as an efficient alternative for electrode linearization. A process of supervised learning is initially used to determine the weighting coefficients, which are subsequently applied to the incoming electrode data. A non-linear layer, known as an activation layer, is responsible for the removal of saturation effects. Implementationmore » of a perceptron in an FPGA-based software-defined radio (SDR) is presented, along with performance comparisons. In addition, efficient calculation of the sigmoidal activation function via the CORDIC algorithm is presented.« less

Swarm formation control utilizing elliptical surfaces and limiting functions.

PubMed

Barnes, Laura E; Fields, Mary Anne; Valavanis, Kimon P

2009-12-01

In this paper, we present a strategy for organizing swarms of unmanned vehicles into a formation by utilizing artificial potential fields that were generated from normal and sigmoid functions. These functions construct the surface on which swarm members travel, controlling the overall swarm geometry and the individual member spacing. Nonlinear limiting functions are defined to provide tighter swarm control by modifying and adjusting a set of control variables that force the swarm to behave according to set constraints, formation, and member spacing. The artificial potential functions and limiting functions are combined to control swarm formation, orientation, and swarm movement as a whole. Parameters are chosen based on desired formation and user-defined constraints. This approach is computationally efficient and scales well to different swarm sizes, to heterogeneous systems, and to both centralized and decentralized swarm models. Simulation results are presented for a swarm of 10 and 40 robots that follow circle, ellipse, and wedge formations. Experimental results are included to demonstrate the applicability of the approach on a swarm of four custom-built unmanned ground vehicles (UGVs).

Automatic rectum limit detection by anatomical markers correlation.

PubMed

Namías, R; D'Amato, J P; del Fresno, M; Vénere, M

2014-06-01

Several diseases take place at the end of the digestive system. Many of them can be diagnosed by means of different medical imaging modalities together with computer aided detection (CAD) systems. These CAD systems mainly focus on the complete segmentation of the digestive tube. However, the detection of limits between different sections could provide important information to these systems. In this paper we present an automatic method for detecting the rectum and sigmoid colon limit using a novel global curvature analysis over the centerline of the segmented digestive tube in different imaging modalities. The results are compared with the gold standard rectum upper limit through a validation scheme comprising two different anatomical markers: the third sacral vertebra and the average rectum length. Experimental results in both magnetic resonance imaging (MRI) and computed tomography colonography (CTC) acquisitions show the efficacy of the proposed strategy in automatic detection of rectum limits. The method is intended for application to the rectum segmentation in MRI for geometrical modeling and as contextual information source in virtual colonoscopies and CAD systems. Copyright © 2014 Elsevier Ltd. All rights reserved.

A designed beta-hairpin forming peptide undergoes a consecutive stepwise process for self-assembly into nanofibrils.

PubMed

Wang, Chong; Sha, Yinlin

2010-04-01

We used a de novo designed, beta-hairpin forming T1 peptide as a model to investigate the kinetics of peptide fibrogenesis by a combination of light scattering (LS), circular dichroism (CD), fluorescence, and atomic force microscopy (AFM). The results demonstrate that the T1 fibrogenesis undergoes a consecutive stepwise process, with a high degree of cooperation, presenting sigmoidal time-courses of the peptide aggregation, the subsequent conformational conversion of the backbone, and the peptide sidechains' rearrangement. We suggest that the conformational conversion was initiated after the peptide aggregates reach a dimensional size threshold, which could be a key step in the formation of beta-structural nuclei that catalyze the subsequent reactions. Furthermore, besides triggering the peptide aggregation, the interactions between the peptide sidechains predominately facilitate the regular alignment of the peptide molecules and the formation of a well-defined suprastructure. This work provides an insight of the hierarchical self-assembly of beta-hairpin forming peptides. It is helpful for designing beta-structural peptides for self-assembly into nanowires, which would have potential applications in the construction of nano-materials.

Enzyme-based logic gates and circuits-analytical applications and interfacing with electronics.

PubMed

Katz, Evgeny; Poghossian, Arshak; Schöning, Michael J

2017-01-01

The paper is an overview of enzyme-based logic gates and their short circuits, with specific examples of Boolean AND and OR gates, and concatenated logic gates composed of multi-step enzyme-biocatalyzed reactions. Noise formation in the biocatalytic reactions and its decrease by adding a "filter" system, converting convex to sigmoid response function, are discussed. Despite the fact that the enzyme-based logic gates are primarily considered as components of future biomolecular computing systems, their biosensing applications are promising for immediate practical use. Analytical use of the enzyme logic systems in biomedical and forensic applications is discussed and exemplified with the logic analysis of biomarkers of various injuries, e.g., liver injury, and with analysis of biomarkers characteristic of different ethnicity found in blood samples on a crime scene. Interfacing of enzyme logic systems with modified electrodes and semiconductor devices is discussed, giving particular attention to the interfaces functionalized with signal-responsive materials. Future perspectives in the design of the biomolecular logic systems and their applications are discussed in the conclusion. Graphical Abstract Various applications and signal-transduction methods are reviewed for enzyme-based logic systems.

Septic arthritis as a presentation of Crohn's disease.

PubMed

Zaidi, R; Dala-Ali, B; Dalton, D J N

2011-09-01

A 42-year-old man with colonic Crohn's disease presented to the orthopaedic department with septic arthritis of the knee with frank intra-articular pus, which persisted despite repeated joint washouts. This coincided with a symptomatic flare of his colonic Crohns. Imaging revealed a fistulous connection from the proximal sigmoid colon into the pelvis, a psoas abscess, myositis of the musculature around the left pelvic girdle and left thigh and two focal collections almost surrounding the distal femur. The knee symptoms only settled after laparotomy and resection of the diseased sigmoid colon and fistula. This case report demonstrates an unusual presentation of fistulating Crohns disease as septic arthritis.

[Delayed perforation of the cecum and sigmoid colon after blunt abdominal trauma in a patient with multiple injuries].

PubMed

Miranda, E; Arroyo, A; Ronda, J M; Muñoz, J L; Alonso, C; Martínez-Peñuelas, F; Martí-Viaño, J L

2007-01-01

Blunt abdominal trauma can damage the intestinal vasculature and may occasionally lead to delayed intestinal perforation, associated with a combined rate of morbidity and mortality of 25%. The diagnosis of such complications is hindered by sedation in critical patients, however, and morbimortality in this population is therefore higher. We report the case of a man with multiple injuries admitted to the intensive care unit, where delayed perforations of the sigmoid colon and cecum were diagnosed. The management of blunt abdominal trauma is reviewed and the possible causes, diagnostic approaches, and treatment options for colon injuries are discussed.

FIP bias in a sigmoidal active region

NASA Astrophysics Data System (ADS)

Baker, D.; Brooks, D. H.; Démoulin, P.; van Driel-Gesztelyi, Lidia; Green, L. M.; Steed, K.; Carlyle, J.

2014-01-01

We investigate first ionization potential (FIP) bias levels in an anemone active region (AR) - coronal hole (CH) complex using an abundance map derived from Hinode/EIS spectra. The detailed, spatially resolved abundance map has a large field of view covering 359'' × 485''. Plasma with high FIP bias, or coronal abundances, is concentrated at the footpoints of the AR loops whereas the surrounding CH has a low FIP bias, ~1, i.e. photospheric abundances. A channel of low FIP bias is located along the AR's main polarity inversion line containing a filament where ongoing flux cancellation is observed, indicating a bald patch magnetic topology characteristic of a sigmoid/flux rope configuration.

Robust Bioinformatics Recognition with VLSI Biochip Microsystem

NASA Technical Reports Server (NTRS)

Lue, Jaw-Chyng L.; Fang, Wai-Chi

2006-01-01

A microsystem architecture for real-time, on-site, robust bioinformatic patterns recognition and analysis has been proposed. This system is compatible with on-chip DNA analysis means such as polymerase chain reaction (PCR)amplification. A corresponding novel artificial neural network (ANN) learning algorithm using new sigmoid-logarithmic transfer function based on error backpropagation (EBP) algorithm is invented. Our results show the trained new ANN can recognize low fluorescence patterns better than the conventional sigmoidal ANN does. A differential logarithmic imaging chip is designed for calculating logarithm of relative intensities of fluorescence signals. The single-rail logarithmic circuit and a prototype ANN chip are designed, fabricated and characterized.

Filament Chirality over an Entire Cycle Determined with an Automated Detection Module -- a Neat Surprise!

NASA Astrophysics Data System (ADS)

Martens, Petrus C.; Yeates, A. R.; Mackay, D.; Pillai, K. G.

2013-07-01

Using metadata produced by automated solar feature detection modules developed for SDO (Martens et al. 2012) we have discovered some trends in filament chirality and filament-sigmoid relations that are new and in part contradict the current consensus. Automated detection of solar features has the advantage over manual detection of having the detection criteria applied consistently, and in being able to deal with enormous amounts of data, like the 1 Terabyte per day that SDO produces. Here we use the filament detection module developed by Bernasconi, which has metadata from 2000 on, and the sigmoid sniffer, which has been producing metadata from AIA 94 A images since October 2011. The most interesting result we find is that the hemispheric chirality preference for filaments (dextral in the north, and v.v.), studied in detail for a three year period by Pevtsov et al. (2003) seems to disappear during parts of the decline of cycle 23 and during the extended solar minimum that followed. Moreover the hemispheric chirality rule seems to be much less pronounced during the onset of cycle 24. For sigmoids we find the expected correlation between chirality and handedness (S or Z) shape but not as strong as expected.

Immunotherapy for pulmonary squamous cell carcinoma and colon carcinoma with pembrolizumab: A case report.

PubMed

Nozawa, Yoshihiro; Oka, Yuka; Oosugi, Jun; Takemura, Shinichi

2018-05-01

Novel treatment strategies such as immunotherapy are being evaluated to further improve the outcomes of colorectal cancer patients. To our knowledge, this is the first report to show both the successful treatment of pulmonary squamous cell carcinoma (SCC) with pembrolizumab alongside histological and immunohistochemical findings of resected colon cancer under immunotherapy for lung cancer. This patient was a 70-year-old man who presented with a right lung tumor and simultaneous adenocarcinoma of the sigmoid colon. Biopsy examination revealed squamous cell carcinoma in the right lung and adenocarcinoma of the sigmoid colon. The patient underwent successful pembrolizumab treatment as first-line immunotherapy for lung cancer, as demonstrated by computed tomography, and the sigmoid colon tumor was excised during an immunotherapy-free window. No unusual tumor growth in the right lung or abnormal abdominal signs was observed during the 9-month follow-up. Microscopically, the resected colon cancer specimen was characterized by numerous lymphoid cells in the partial stroma, with a large number of infiltrating lymphocytes consisting of CD3+, CD8+ T cells. In summary, this case demonstrates how immunotherapy affects PD-L1-negative colon cancer and indicates future treatment prospects.

Use of plain radiography in the diagnosis, surgical management, and postoperative treatment of obstructive urolithiasis in 25 goats and 2 sheep.

PubMed

Kinsley, Marc A; Semevolos, Stacy; Parker, Jill E; Duesterdieck-Zellmer, Katja; Huber, Michael

2013-08-01

To describe use of plain radiography for diagnosis, surgical management, and postoperative treatment of obstructive urolithiasis in small ruminants. Retrospective case series. Small ruminants (n = 27; 25 goats, 2 sheep). Medical records (January 2002-November 2011) and radiographs for all small ruminants diagnosed with obstructive urolithiasis and having plain abdominal radiographs were reviewed. Signalment, surgical procedures, radiographic findings, ultrasonographic findings, position of calculi, and how plain radiography influenced surgical management and postoperative treatment were recorded. Radiopaque urinary calculi were detected in 23 (85%) plain radiographic studies. Location of uroliths determined by plain radiography included: cystic only (n = 5), distal to the sigmoid flexure and cystic (5), subischial (5), distal to the sigmoid flexure only (3), sigmoid flexure (3), and subischial and cystic (2). In 8 of these animals, postoperative radiographs revealed residual calculi in the urethra and were essential for their targeted removal by urethrotomy in 7 animals. In regions where radiopaque calculi (calcium carbonate, calcium oxalate, silica) are commonly encountered in small ruminants, plain radiographs are recommended to determine the appropriate surgical approach(es) and to confirm resolution of the obstruction. © Copyright 2013 by The American College of Veterinary Surgeons.

[A Case of Sigmoid Colon Cancer with Metastasis to the Uterus].

PubMed

Tokoro, Yukinari; Tonooka, Toru; Souda, Hiroaki; Takiguchi, Nobuhiro; Chibana, Tomofumi; Kobayashi, Ryosuke; Arimitsu, Hidehito; Yanagibashi, Hiroo; Chou, Akihiro; Ikeda, Atsushi; Nabeya, Nobuhiro; Kainuma, Osamu; Yamamoto, Hiroshi; Nagata, Matsuo

2015-11-01

A 65-year-old woman complaining of fetor ex vagina was diagnosed with endometrial adenocarcinoma of the uterus based on the pathological findings of an endometrial biopsy. Sigmoid colon cancer was found on a pre-operative CT scan. Diagnosis of double cancer was made and we performed sigmoidectomy and panhysterectomy with associated resection of both adnexa. Histopathological examination found that the tumor accounted for almost all of the uterine mucosa and over half of the muscular layer. Immunostaining showed CK7 (-), CK20 (+), CDX2 (+), ER (-), and PgR (-), and we diagnosed it as a metastasis to the uterus of the sigmoid colon cancer. The pathological diagnosis was a moderately differentiated adenocarcinoma, pT4b (SI: urinary bladder), pN0 (0/12), H0, P1,M1a (uterus), pStage Ⅳ. As adjuvant chemotherapy, she was administered XELOX for 6 months. Although colorectal cancer rarely metastasizes to the uterus, due to the increase in the prevalence of colorectal cancer, it may be also increase. To choose the best treatment course, it is necessary to diagnose whether it is a primary uterine cancer or a metastatic uterine cancer.

Laparoscopic colectomy for diverticulitis is not associated with increased morbidity when compared with non-diverticular disease.

PubMed

Schwandner, O; Farke, S; Bruch, H-P

2005-03-01

It was the aim of this prospective study to compare the outcome of laparoscopic sigmoid and anterior resection for diverticulitis and non-diverticular disease. All patients who underwent laparoscopic colectomy for benign and malignant disease within a 10-year period were entered into the prospective PC database registry. For outcome analysis, patients who underwent laparoscopic sigmoid and anterior resection for diverticular disease were compared with patients who underwent the same operation for non-inflammatory (non-diverticular) disease. The parameters analyzed included age, gender, co-morbid conditions, diagnosis, procedure, duration of surgery, transfusion requirements, conversion, morbidity including major (requiring reoperation), minor (conservative treatment) and late-onset (postdischarge) complications, stay in the ICU, hospitalization, and mortality. For objective evaluation, only laparoscopically completed procedures were analyzed. Statistics included Student's t-test and chi-square analysis (p<0.05 was considered statistically significant). A total of 676 patients were evaluated including 363 with diverticular disease and 313 with non-inflammatory disease. There were no significant differences in conversion rates (6.6 vs. 7.3%, p>0.05), so that the laparoscopic completion rate was 93.4% (n=339) in the diverticulitis group and 92.7% (n=290) in the non-diverticulitis group. The two groups did not differ significantly in age or presence of co-morbid conditions (p>0.05). In the diverticulitis group, recurrent diverticulitis (58.4%), and complicated diverticulitis (27.7%) were the most common indications, whereas in the non-diverticulitis group, outlet obstruction by sigmoidoceles (30.0%) and cancer (32.4%) were the main indications. The most common procedure was laparoscopic sigmoid resection, followed by sigmoid resection with rectopexy and anterior resection. No significant differences were documented for major complications (7.4 vs. 7.9%), minor complications (11.5 vs. 14.5%), late-onset complications (3.0 vs. 3.5), reoperation (8.6 vs. 9.3%) or mortality (0.6 vs. 0.7%) between the two groups (p>0.05). In the postoperative course, no differences were noted in terms of stay in the ICU, postoperative ileus, parenteral analgesics, oral feeding, and length of hospitalization (p>0.05). These data indicate that laparoscopic sigmoid and anterior resection can be performed with acceptable morbidity and mortality for both diverticular disease and non-diverticular disease. The results show in particular that laparoscopic resection for inflammation is not associated with increased morbidity.

Impact of valve-less vs. standard insufflation on pneumoperitoneum volume, inflammation, and peritoneal physiology in a laparoscopic sigmoid resection experimental model.

PubMed

Diana, Michele; Noll, Eric; Legnèr, Andras; Kong, Seong-Ho; Liu, Yu-Yin; Schiraldi, Luigi; Marchegiani, Francesco; Bano, Jordan; Geny, Bernard; Charles, Anne-Laure; Dallemagne, Bernard; Lindner, Véronique; Mutter, Didier; Diemunsch, Pierre; Marescaux, Jacques

2018-07-01

Standard insufflators compensate for intra-abdominal pressure variations with pressure spikes. Our aim was to evaluate the impact of a stable, low-pressure pneumoperitoneum induced by a valve-less insufflator, on working space, hemodynamics, inflammation, and peritoneal physiology, in a model of laparoscopic sigmoid resection. Twelve pigs (47 ± 3.3 kg) were equipped for invasive hemodynamic monitoring and randomly assigned to Standard (n = 6) vs. valve-less (n = 6) insufflation. Animals were positioned in a 30° Trendelenburg on a CT scan bed. A low-pressure pneumoperitoneum (8 mmHg) was started and duration was set for 180 min. Abdominal CT scans were performed, under neuromuscular blockade, before, immediately after, and 1 and 3 h after insufflation. Pneumoperitoneum volumes were calculated on 3D reconstructed CT scans. After creation of a mesenteric window, capillary blood was obtained by puncturing the sigmoid serosa and local lactatemia (mmol/L) was measured using a handheld analyzer. Surgical resection was performed according to the level of lactates, in order to standardize bowel stump perfusion. IL-1 and IL-6 (ng/mL) were measured repeatedly. The peritoneum was sampled close to the surgical site and distantly for the oxygraphic assessment of mitochondrial respiration. A pathologist applied a semi-quantitative score to evaluate the anastomosis. Mean arterial pressure, pulse, body temperature, oximetry, systemic lactatemia, and local lactates were similar. IL-6 was lower in the valve-less group, reaching a statistically significant difference after 3 h of insufflation (64.85 ± 32.5 vs. 133.95 ± 59.73; p = 0.038) and 48 h (77.53 ± 68.4 vs. 190.74 ± 140.79; p = 0.029). Peritoneal mitochondrial respiration was significantly increased after the survival period, with no difference among the groups. The anastomoses in the valve-less group demonstrated a lower acute (p = 0.04) inflammatory infiltration. The mean anterior posterior thickness was slightly, yet significantly higher in the valve-less group, on all post-insufflation CT scans. Valve-less insufflation achieved a slightly higher working space and a lower systemic and localized inflammatory response in this experimental setting.

Thermal inactivation kinetics of Lactococcus lactis subsp. lactis bacteriophage pll98-22.

PubMed

Sanlibaba, Pinar; Buzrul, S; Akkoç, Nefise; Alpas, H; Akçelik, M

2009-03-01

Survival curves of Lactococcus lactis subsp. lactis bacteriophage pll98 inactivated by heat were obtained at seven temperature values (50-80 degrees C) in M17 broth and skim milk. Deviations from first-order kinetics in both media were observed as sigmoidal shapes in the survival curves of pll98. An empirical model with four parameters was used to define the thermal inactivation. Number of parameters of the model was reduced from four to two in order to increase the robustness of the model. The reduced model produced comparable fits to the full model. Both the survival data and the calculations done using the reduced model (time necessary to reduce the number of phage pll98 six- or seven- log10) indicated that skim milk is a more protective medium than M17 broth within the assayed temperature range.

Arabidopsis thaliana as a model species for xylem hydraulics: does size matter?

PubMed Central

Tixier, Aude; Cochard, Hervé; Badel, Eric; Dusotoit-Coucaud, Anaïs; Jansen, Steven; Herbette, Stéphane

2013-01-01

While Arabidopsis thaliana has been proposed as a model species for wood development, the potential of this tiny herb for studying xylem hydraulics remains unexplored and anticipated by scepticism. Inflorescence stems of A. thaliana were used to measure hydraulic conductivity and cavitation resistance, whereas light and electron microscopy allowed observations of vessels. In wild-type plants, measured and theoretical conductivity showed a significant correlation (R 2 = 0.80, P < 0.01). Moreover, scaling of vessel dimensions and intervessel pit structure of A. thaliana were consistent with structure–function relationships of woody plants. The reliability and resolution of the hydraulic methods applied to measure vulnerability to cavitation were addressed by comparing plants grown under different photoperiods or different mutant lines. Sigmoid vulnerability curves of A. thaliana indicated a pressure corresponding to 50% loss of hydraulic conductance (P 50) between –3 and –2.5MPa for short-day and long-day plants, respectively. Polygalacturonase mutants showed a higher P 50 value (–2.25MPa), suggesting a role for pectins in vulnerability to cavitation. The application of A. thaliana as a model species for xylem hydraulics provides exciting possibilities for (1) exploring the molecular basis of xylem anatomical features and (2) understanding genetic mechanisms behind xylem functional traits such as cavitation resistance. Compared to perennial woody species, however, the lesser amount of xylem in A. thaliana has its limitations. PMID:23547109

Arabidopsis thaliana as a model species for xylem hydraulics: does size matter?

PubMed

Tixier, Aude; Cochard, Hervé; Badel, Eric; Dusotoit-Coucaud, Anaïs; Jansen, Steven; Herbette, Stéphane

2013-05-01

While Arabidopsis thaliana has been proposed as a model species for wood development, the potential of this tiny herb for studying xylem hydraulics remains unexplored and anticipated by scepticism. Inflorescence stems of A. thaliana were used to measure hydraulic conductivity and cavitation resistance, whereas light and electron microscopy allowed observations of vessels. In wild-type plants, measured and theoretical conductivity showed a significant correlation (R (2) = 0.80, P < 0.01). Moreover, scaling of vessel dimensions and intervessel pit structure of A. thaliana were consistent with structure-function relationships of woody plants. The reliability and resolution of the hydraulic methods applied to measure vulnerability to cavitation were addressed by comparing plants grown under different photoperiods or different mutant lines. Sigmoid vulnerability curves of A. thaliana indicated a pressure corresponding to 50% loss of hydraulic conductance (P 50) between -3 and -2.5MPa for short-day and long-day plants, respectively. Polygalacturonase mutants showed a higher P 50 value (-2.25MPa), suggesting a role for pectins in vulnerability to cavitation. The application of A. thaliana as a model species for xylem hydraulics provides exciting possibilities for (1) exploring the molecular basis of xylem anatomical features and (2) understanding genetic mechanisms behind xylem functional traits such as cavitation resistance. Compared to perennial woody species, however, the lesser amount of xylem in A. thaliana has its limitations.

Neural networks with local receptive fields and superlinear VC dimension.

PubMed

Schmitt, Michael

2002-04-01

Local receptive field neurons comprise such well-known and widely used unit types as radial basis function (RBF) neurons and neurons with center-surround receptive field. We study the Vapnik-Chervonenkis (VC) dimension of feedforward neural networks with one hidden layer of these units. For several variants of local receptive field neurons, we show that the VC dimension of these networks is superlinear. In particular, we establish the bound Omega(W log k) for any reasonably sized network with W parameters and k hidden nodes. This bound is shown to hold for discrete center-surround receptive field neurons, which are physiologically relevant models of cells in the mammalian visual system, for neurons computing a difference of gaussians, which are popular in computational vision, and for standard RBF neurons, a major alternative to sigmoidal neurons in artificial neural networks. The result for RBF neural networks is of particular interest since it answers a question that has been open for several years. The results also give rise to lower bounds for networks with fixed input dimension. Regarding constants, all bounds are larger than those known thus far for similar architectures with sigmoidal neurons. The superlinear lower bounds contrast with linear upper bounds for single local receptive field neurons also derived here.

POOL server: machine learning application for functional site prediction in proteins.

PubMed

Somarowthu, Srinivas; Ondrechen, Mary Jo

2012-08-01

We present an automated web server for partial order optimum likelihood (POOL), a machine learning application that combines computed electrostatic and geometric information for high-performance prediction of catalytic residues from 3D structures. Input features consist of THEMATICS electrostatics data and pocket information from ConCavity. THEMATICS measures deviation from typical, sigmoidal titration behavior to identify functionally important residues and ConCavity identifies binding pockets by analyzing the surface geometry of protein structures. Both THEMATICS and ConCavity (structure only) do not require the query protein to have any sequence or structure similarity to other proteins. Hence, POOL is applicable to proteins with novel folds and engineered proteins. As an additional option for cases where sequence homologues are available, users can include evolutionary information from INTREPID for enhanced accuracy in site prediction. The web site is free and open to all users with no login requirements at http://www.pool.neu.edu. m.ondrechen@neu.edu Supplementary data are available at Bioinformatics online.

Tree cover in sub-Saharan Africa: rainfall and fire constrain forest and savanna as alternative stable states.

PubMed

Staver, A Carla; Archibald, Sally; Levin, Simon

2011-05-01

Savannas are known as ecosystems with tree cover below climate-defined equilibrium values. However, a predictive framework for understanding constraints on tree cover is lacking. We present (a) a spatially extensive analysis of tree cover and fire distribution in sub-Saharan Africa, and (b) a model, based on empirical results, demonstrating that savanna and forest may be alternative stable states in parts of Africa, with implications for understanding savanna distributions. Tree cover does not increase continuously with rainfall, but rather is constrained to low (<50%, "savanna") or high tree cover (>75%, "forest"). Intermediate tree cover rarely occurs. Fire, which prevents trees from establishing, differentiates high and low tree cover, especially in areas with rainfall between 1000 mm and 2000 mm. Fire is less important at low rainfall (<1000 mm), where rainfall limits tree cover, and at high rainfall (>2000 mm), where fire is rare. This pattern suggests that complex interactions between climate and disturbance produce emergent alternative states in tree cover. The relationship between tree cover and fire was incorporated into a dynamic model including grass, savanna tree saplings, and savanna trees. Only recruitment from sapling to adult tree varied depending on the amount of grass in the system. Based on our empirical analysis and previous work, fires spread only at tree cover of 40% or less, producing a sigmoidal fire probability distribution as a function of grass cover and therefore a sigmoidal sapling to tree recruitment function. This model demonstrates that, given relatively conservative and empirically supported assumptions about the establishment of trees in savannas, alternative stable states for the same set of environmental conditions (i.e., model parameters) are possible via a fire feedback mechanism. Integrating alternative stable state dynamics into models of biome distributions could improve our ability to predict changes in biome distributions and in carbon storage under climate and global change scenarios.

Numerical Analysis of Modeling Based on Improved Elman Neural Network

PubMed Central

Jie, Shao

2014-01-01

A modeling based on the improved Elman neural network (IENN) is proposed to analyze the nonlinear circuits with the memory effect. The hidden layer neurons are activated by a group of Chebyshev orthogonal basis functions instead of sigmoid functions in this model. The error curves of the sum of squared error (SSE) varying with the number of hidden neurons and the iteration step are studied to determine the number of the hidden layer neurons. Simulation results of the half-bridge class-D power amplifier (CDPA) with two-tone signal and broadband signals as input have shown that the proposed behavioral modeling can reconstruct the system of CDPAs accurately and depict the memory effect of CDPAs well. Compared with Volterra-Laguerre (VL) model, Chebyshev neural network (CNN) model, and basic Elman neural network (BENN) model, the proposed model has better performance. PMID:25054172

Robotic surgery for colorectal cancer: systematic review of the literature.

PubMed

Papanikolaou, Ioannis G

2014-12-01

Surgical practice has been changed since the introduction of robotic techniques and robotic colorectal surgery is an emerging field. Innovative robotic technologies have helped surgeons overcome many technical difficulties of conventional laparoscopic surgery. Herein, we review the clinical studies regarding the application of surgical robots in resections for colorectal cancer. A systematic review of the literature was conducted for articles published up to September 9, 2012, using the MEDLINE database. The keywords that were used in various combinations were: "surgical robotics," "robotic surgery," "computer-assisted surgery," "colectomy," "sigmoid resection," "sigmoidectomy," and "rectal resection." Fifty-nine articles reporting on robot-assisted resections of colon and/or rectum were identified and 41 studies were finally included in the analysis. A total of 1635 colorectal procedures were performed: 254 right colectomies, 185 left colectomies/sigmoid resections, 969 anterior resections, 182 abdominoperineal or intersphincteric resections, 34 colectomies (without being specified as right or left), and 11 total/subtotal colectomies. In general, blood loss, conversion rates, and complications were low but the operative time was longer than the open procedures, whereas the duration of hospitalization was shorter. The number of harvested lymph nodes was also quite satisfactory. Robotic colorectal operations provide favorable results, with acceptable operative times and low conversion rates and morbidity. Surgical robots may provide additional benefits treating challenging pathologies, such as rectal cancer. Further clinical studies and long-term follow-up are required to better evaluate the outcomes of robotic colorectal surgery.

A simplified technique for a totally diverting transverse loop colostomy and distal irrigation.

PubMed

Rose, D; Koniges, F; Frazier, T G

1985-12-01

This technique of totally diverting loop colostomy may be performed as an independent procedure or with exploratory laparotomy and surgical treatment on the distal part of the colon. Either a transverse or sigmoid loop colostomy can be used for diversion without the risk of fecal contamination of the peritoneal cavity, particularly when working with unprepared intestine. When distal irrigation is desired to purge the intestine of fecal material, either intraoperatively or as part of a subsequent intestinal preparation, it can easily be accomplished by placing an irrigating catheter distal to the staple line. In addition, the use of a small rubber suspension bar facilitates application of standard colostomy appliances for the stoma.

Improved prediction of higher heating value of biomass using an artificial neural network model based on proximate analysis.

PubMed

Uzun, Harun; Yıldız, Zeynep; Goldfarb, Jillian L; Ceylan, Selim

2017-06-01

As biomass becomes more integrated into our energy feedstocks, the ability to predict its combustion enthalpies from routine data such as carbon, ash, and moisture content enables rapid decisions about utilization. The present work constructs a novel artificial neural network model with a 3-3-1 tangent sigmoid architecture to predict biomasses' higher heating values from only their proximate analyses, requiring minimal specificity as compared to models based on elemental composition. The model presented has a considerably higher correlation coefficient (0.963) and lower root mean square (0.375), mean absolute (0.328), and mean bias errors (0.010) than other models presented in the literature which, at least when applied to the present data set, tend to under-predict the combustion enthalpy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Unusual Morphological Alteration in Sigmoid Notch: An Insight Through CBCT

PubMed Central

Gupta, Anjali; Phulambrikar, Tushar; Kode, Manasi; Singh, Siddharth Kumar

2015-01-01

The Temporomandibular Joint (TMJ) is a ginglymo-diarthrodial joint known to be the most complex joint in human body. Growth disturbances, owing to genetic influences or trauma during the intrauterine life or during early developmental age may lead to morphological and functional variations in the mandible resulting in developmental anomaly. We report a rare case of altered sigmoid notch morphology on the right side and condylar hypoplasia on the left side, not related to any clear pathological disorder. Cone Beam Computed Tomography (CBCT) was helpful in evaluating this case. This case of unknown aetiology was thoroughly examined; based on clinical and radiographic findings, we suggest that this case is of congenital origin. PMID:26816996

[A case of intragastric wall abscess formation during bevacizumab combined chemotherapy].

PubMed

Mori, Ayano; Kogawa, Takahiro; Arihara, Youhei; Abe, Masakazu; Tamura, Fumito; Abe, Seiichirou; Kukitsu, Takehiro; Ihara, Hideyuki; Sumiyoshi, Tetsuya; Yoshizaki, Naoto; Kondou, Hitoshi; Tsuji, Yasushi

2013-05-01

A 38-year-old man was given a diagnosis of as sigmoid colon cancer and underwent sigmoid colectomy. Post-operative pathological staging was stage IIIb. He then underwent adjuvant chemotherapy. One year and 4 months after the surgery, CT scans revealed multiple liver and lung metastases. He was given mFOLFOX6+bevacizumab, which was changed later to FOLFIRI+bevacizumab. After these chemotherapies, he was admitted to the hospital due to sudden abdominal pain and high grade fever. Obstructive jaundice was initially diagnosed, but detailed study of initial CT revealed intragastric wall abscess. After the drainage of the abscess, his conditions improved. We speculated that the abscess formation was caused by mucosal damage due to bevacizumab.

Segmental dilatation of sigmoid colon in a neonate: atypical presentation and histology.

PubMed

Mahadevaiah, Shubha Attibele; Panjwani, Poonam; Kini, Usha; Mohanty, Suravi; Das, Kanishka

2011-03-01

Segmental dilatation of the colon is a rare disorder of colonic motility in children, often presenting with severe constipation in older infants, children, and occasionally adults. It may mimic the commoner Hirschsprung disease clinicoradiologically but differs in that the ganglion cell morphology and distribution are typically normal in the colon. We report a neonate with segmental dilatation of the sigmoid colon who had an atypical clinical presentation and describe certain abnormalities in bowel histology (hypertrophied muscularis propria, nerve plexus, and ganglion cells located within the circular layer rather than the normal myenteric location), for the first time in the English literature. Copyright © 2011 Elsevier Inc. All rights reserved.

Submucosal lipoma of the sigmoid colon as a rare cause of mucoid diarrhea: a case report.

PubMed

Dassanayake, S U B; Dinamithra, N P; Nawarathne, N M M

2016-01-20

Symptomatic presentations of colonic lipomas are very rare in clinical practice, and may mimic colonic malignancy. The likelihood of presenting symptoms has been shown to depend on the size of the lesion. We describe the case of a 72-year-old Sinhalese man presenting with worsening mucoid diarrhea who was subsequently diagnosed to have a lipoma of the sigmoid colon. His disease was successfully managed with endoscopic resection. Confidently establishing the rare diagnosis of a colonic lipoma usually requires a combination of endoscopic, radiological, and histological evaluation, and is therefore very challenging. With the advancement of endoscopic procedures, endoscopic resection is widely practiced as the definitive management of these cases.

Artificial neural network (ANN)-based prediction of depth filter loading capacity for filter sizing.

PubMed

Agarwal, Harshit; Rathore, Anurag S; Hadpe, Sandeep Ramesh; Alva, Solomon J

2016-11-01

This article presents an application of artificial neural network (ANN) modelling towards prediction of depth filter loading capacity for clarification of a monoclonal antibody (mAb) product during commercial manufacturing. The effect of operating parameters on filter loading capacity was evaluated based on the analysis of change in the differential pressure (DP) as a function of time. The proposed ANN model uses inlet stream properties (feed turbidity, feed cell count, feed cell viability), flux, and time to predict the corresponding DP. The ANN contained a single output layer with ten neurons in hidden layer and employed a sigmoidal activation function. This network was trained with 174 training points, 37 validation points, and 37 test points. Further, a pressure cut-off of 1.1 bar was used for sizing the filter area required under each operating condition. The modelling results showed that there was excellent agreement between the predicted and experimental data with a regression coefficient (R 2 ) of 0.98. The developed ANN model was used for performing variable depth filter sizing for different clarification lots. Monte-Carlo simulation was performed to estimate the cost savings by using different filter areas for different clarification lots rather than using the same filter area. A 10% saving in cost of goods was obtained for this operation. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1436-1443, 2016. © 2016 American Institute of Chemical Engineers.

The influence of filtering and downsampling on the estimation of transfer entropy

PubMed Central

Florin, Esther; von Papen, Michael; Timmermann, Lars

2017-01-01

Transfer entropy (TE) provides a generalized and model-free framework to study Wiener-Granger causality between brain regions. Because of its nonparametric character, TE can infer directed information flow also from nonlinear systems. Despite its increasing number of applications in neuroscience, not much is known regarding the influence of common electrophysiological preprocessing on its estimation. We test the influence of filtering and downsampling on a recently proposed nearest neighborhood based TE estimator. Different filter settings and downsampling factors were tested in a simulation framework using a model with a linear coupling function and two nonlinear models with sigmoid and logistic coupling functions. For nonlinear coupling and progressively lower low-pass filter cut-off frequencies up to 72% false negative direct connections and up to 26% false positive connections were identified. In contrast, for the linear model, a monotonic increase was only observed for missed indirect connections (up to 86%). High-pass filtering (1 Hz, 2 Hz) had no impact on TE estimation. After low-pass filtering interaction delays were significantly underestimated. Downsampling the data by a factor greater than the assumed interaction delay erased most of the transmitted information and thus led to a very high percentage (67–100%) of false negative direct connections. Low-pass filtering increases the number of missed connections depending on the filters cut-off frequency. Downsampling should only be done if the sampling factor is smaller than the smallest assumed interaction delay of the analyzed network. PMID:29149201

Application of kinetic models to the design of a calcite permeable reactive barrier (PRB) for fluoride remediation.

PubMed

Cai, Qianqian; Turner, Brett D; Sheng, Daichao; Sloan, Scott

2018-03-01

The kinetics of fluoride sorption by calcite in the presence of metal ions (Co, Mn, Cd and Ba) have been investigated and modelled using the intra-particle diffusion (IPD), pseudo-second order (PSO), and the Hill 4 and Hill 5 kinetic models. Model comparison using the Akaike Information Criterion (AIC), the Schwarz Bayseian Information Criterion (BIC) and the Bayes Factor allows direct comparison of model results irrespective of the number of model parameters. Information Criterion results indicate "very strong" evidence that the Hill 5 model was the best fitting model for all observed data due to its ability to fit sigmoidal data, with confidence contour analysis showing the model parameters were well constrained by the data. Kinetic results were used to determine the thickness of a calcite permeable reactive barrier required to achieve up to 99.9% fluoride removal at a groundwater flow of 0.1 m.day -1 . Fluoride removal half-life (t 0.5 ) values were found to increase in the order Ba ≈ stonedust (a 99% pure natural calcite) < Cd < Co < Mn. A barrier width of 0.97 ± 0.02 m was found to be required for the fluoride/calcite (stonedust) only system when using no factor of safety, whilst in the presence of Mn and Co, the width increased to 2.76 ± 0.28 and 19.83 ± 0.37 m respectively. In comparison, the PSO model predicted a required barrier thickness of ∼46.0, 62.6 & 50.3 m respectively for the fluoride/calcite, Mn and Co systems under the same conditions. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Modeling monthly meteorological and agronomic frost days, based on minimum air temperature, in Center-Southern Brazil

NASA Astrophysics Data System (ADS)

Alvares, Clayton Alcarde; Sentelhas, Paulo César; Stape, José Luiz

2017-09-01

Although Brazil is predominantly a tropical country, frosts are observed with relative high frequency in the Center-Southern states of the country, affecting mainly agriculture, forestry, and human activities. Therefore, information about the frost climatology is of high importance for planning of these activities. Based on that, the aims of the present study were to develop monthly meteorological (F MET) and agronomic (F AGR) frost day models, based on minimum shelter air temperature (T MN), in order to characterize the temporal and spatial frost days variability in Center-Southern Brazil. Daily minimum air temperature data from 244 weather stations distributed across the study area were used, being 195 for developing the models and 49 for validating them. Multivariate regression models were obtained to estimate the monthly T MN, once the frost day models were based on this variable. All T MN regression models were statistically significant (p < 0.001), presenting adjusted R 2 between 0.69 and 0.90. Center-Southern Brazil is mainly hit by frosts from mid-fall (April) to mid-spring (October). The period from November to March is considered as frost-free, being very rare a frost day within that period. Monthly F MET and F AGR presented significant sigmoidal relationships with T MN (p < 0.0001), with adjusted R 2 above of 0.82. The residuals of the frost day models were random, which means that the sigmoidal models performed quite well for interpreting the frost day variability throughout the study area. The highlands of Santa Catarina, Rio Grande do Sul, São Paulo, and Minas Gerais had in average more than 25 and 13 frosts per year, respectively, for F MET and F AGR. The F MET and F AGR maps developed in this study for Center-Southern Brazil is a useful tool for farmers, foresters, and researchers, since they contribute to reduce frost spatial and temporal uncertainty, helping in planning project for strategic purposes. Furthermore, the monthly F MET and F AGR maps for this Brazilian region are the first zoning of these variables for the country.

Image-guided brachytherapy for cervical cancer: analysis of D2 cc hot spot in three-dimensional and anatomic factors affecting D2 cc hot spot in organs at risk.

PubMed

Kim, Robert Y; Dragovic, Alek F; Whitley, Alexander C; Shen, Sui

2014-01-01

To analyze the D2 cc hot spot in three-dimensional CT and anatomic factors affecting the D2 cc hot spot in organs at risk (OARs). Thirty-one patients underwent pelvic CT scan after insertion of the applicator. High-dose-rate treatment planning was performed with standard loading patterns. The D2 cc structures in OARs were generated in three dimensional if the total equivalent dose in 2 Gy exceeded our defined dose limits (hot spot). The location of D2 cc hot spot was defined as the center of the largest D2 cc fragment. The relationship between the hot spot and the applicator position was reported in Digital Imaging and Communication in Medicine coordinates. The location of sigmoid, small bowel, and bladder D2 cc hot spots was around the endocervix: The mean location of sigmoid hot spot for lateral view was 1.6 cm posteriorly and 2.3 cm superiorly (Y, 1.6 and Z, 2.3), small bowel was 1.6 cm anteriorly and 2.7 cm superiorly (Y, -1.6 and Z, 2.7). The mean location of bladder hot spot was 1.6 cm anteriorly and 1.6 cm superiorly (Y, -1.6 and Z, 1.6). These hot spots were near the plane of Point A (X, 2.0 or -2.0; Y, 0; and Z, 2.0). The mean location of rectal hot spot was 1.6 cm posteriorly and 1.9 cm inferiorly (Y, 1.6 and Z, -1.9). D2 cc hot spot was affected by uterine wall thickness, uterine tandem position, fibroids, bladder fullness, bowel gas, and vaginal packing. Because of the location of the D2 cc hot spots, larger tumors present a challenge for adequate tumor coverage with a conventional brachytherapy applicator without an interstitial implant. Additionally, anatomic factors were identified which affect the D2 cc hot spot in OARs. Copyright © 2014 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Cryomilled Aluminum with Diamantane: Thermal Characterization by DSC and Effects of Magnesium

NASA Astrophysics Data System (ADS)

Arnold, Michael Colin

Many structural applications require a material that is both lightweight and corrosion resistant, for which aluminum and its alloys may be considered for use if not for their relatively low strength. By improving strength of aluminum through the Hall-Petch mechanism, it could become a more suitable choice for many structural applications. Cryomilling is used as a production technique to strengthen aluminum by reduction of grain size to the 20-50 nm range. Although the powders produced by cryomilling are well within the nanocrystalline regime, the powders experience significant grain growth during consolidation to a solid body. Cryomilled powders have been shown to remain nanocrystalline by introducing a nano-diamond, diamantane to the grain boundaries. To better characterize the thermal stability of the cryomilled powder with diamantane, Differential Scanning Calorimetry (DSC) was used to measure the isothermal heat flow in the 0.6Tm to 0.9Tm range. A model was developed to correlate the isothermal DSC signal to a grain growth curve and grain growth parameters were elucidated by assuming variable boundary mobility with a sigmoidal form. The model revealed a tendency for boundary mobility to transition from an athermal grain growth mechanism to standard thermally activated grain growth. Grain growth parameters were compared to shed light on possible mechanisms of aluminum-diamantane involvement during grain growth. Powders and consolidated samples with very low concentrations of diamantane and with magnesium were observed by TEM, SEM and XRD, and compared both separately and together to characterize the how thermal stability is affected by diamantane concentration and the presence of magnesium.

The binding of terbium ions to tubulin induces ring formation.

PubMed

Monasterio, O; Acoria, M; Díaz, M A; Lagos, R

1993-02-01

The intrinsic fluorescence excitation and emission spectra of chicken brain tubulin showed the characteristic tryptophan fluorescence. The emission spectrum of Tb3+ in the presence of tubulin and GTP excited at 295 nm, showed four peaks, with the maxima at 490, 545, and 586 nm and a minor peak around 620 nm. Titration of tubulin with Tb3+ was followed by the increment in luminescence at 545 nm and showed a sigmoidal curve where the initial lag interval and the maximal luminescence intensity depended on tubulin concentration. The presence of Mg2+, Co2+, and Zn2+ diminished both the sigmoidicity of the curve and the maximal luminescence intensity. Titration of tubulin with Tb3+ also produced a sigmoidal increase in turbidity, which was shifted to the left with respect to the luminescence curve. The dependence of turbidity on the wavelength of the Tb(3+)-induced polymers revealed that the large structures formed were not microtubules. Electron microscopy of the aggregates induced by Tb3+ showed mainly a lattice of double rings with side-by-side contacts. These results indicate that Tb3+ induces principally double ring formation and that these rings (33 +/- 2 nm external diameter) aggregate in large-ordered arrays. The luminescence of Tb3+ seems to be induced mainly by the aggregation of rings.

Intensity transform and Wiener filter in measurement of blood flow in arteriography

NASA Astrophysics Data System (ADS)

Nunes, Polyana F.; Franco, Marcelo L. N.; Filho, João. B. D.; Patrocínio, Ana C.

2015-03-01

Using the arteriography examination, it is possible to check anomalies in blood vessels and diseases such as stroke, stenosis, bleeding and especially in the diagnosis of Encephalic Death in comatose individuals. Encephalic death can be diagnosed only when there is complete interruption of all brain functions, and hence the blood stream. During the examination, there may be some interference on the sensors, such as environmental factors, poor maintenance of equipment, patient movement, among other interference, which can directly affect the noise produced in angiography images. Then, we need to use digital image processing techniques to minimize this noise and improve the pixel count. Therefore, this paper proposes to use median filter and enhancement techniques for transformation of intensity using the sigmoid function together with the Wiener filter so you can get less noisy images. It's been realized two filtering techniques to remove the noise of images, one with the median filter and the other with the Wiener filter along the sigmoid function. For 14 tests quantified, including 7 Encephalic Death and 7 other cases, the technique that achieved a most satisfactory number of pixels quantified, also presenting a lesser amount of noise, is the Wiener filter sigmoid function, and in this case used with 0.03 cuttof.

Well differentiated "lipoma-like" liposarcoma of the sigmoid mesocolon and multiple lipomatosis of the rectosigmoid colon. Report of a case.

PubMed

Amato, G; Martella, A; Ferraraccio, F; Di Martino, N; Maffettone, V; Landolfi, V; Fei, L; Del Genio, A

1998-01-01

Liposarcoma is the second most common soft tissue sarcoma in adults. These neoplasms take their origin from primitive mesenchymal cells and are rarely encountered in fat rich areas, such as subcutaneous tissue and/or the subserosa of the intestinal tract which, on the contrary, are the two most common sites of lipomas. The two major locations of liposarcomas are the extremities and the retroperitoneum followed with much less frequency by the inguinal region. Other sites are uncommon, particularly the mesentery (9 cases to date in the literature) and, even more so, the mesocolon (only 3 cases of primary sarcoma of the mesocolon reported to date). This paper reports on the case of a well differentiated "lipoma-like" liposarcoma of the sigmoid mesocolon, associated with multiple lipomatosis of the recto-sigmoid colon in a 75 year-old female patient. Surgical treatment consisted of a trans-anal extra-peritoneal anterior resection by CEEA 28 stapler under endoscopic vision. The patient has been followed up for the last 2 years and is still disease-free and well. The peculiarity of the case consists in the contemporaneous presence in close contiguity of two different rare neoplasms whose association is not yet known.

Long-Term Uptake of Phenol-Water Vapor Follows Similar Sigmoid Kinetics on Prehydrated Organic Matter- and Clay-Rich Soil Sorbents.

PubMed

Borisover, Mikhail; Bukhanovsky, Nadezhda; Lado, Marcos

2017-09-19

Typical experimental time frames allowed for equilibrating water-organic vapors with soil sorbents might lead to overlooking slow chemical reactions finally controlling a thermodynamically stable state. In this work, long-term gravimetric examination of kinetics covering about 4000 h was performed for phenol-water vapor interacting with four materials pre-equilibrated at three levels of air relative humidity (RHs 52, 73, and 92%). The four contrasting sorbents included an organic matter (OM)-rich peat soil, an OM-poor clay soil, a hydrophilic Aldrich humic acid salt, and water-insoluble leonardite. Monitoring phenol-water vapor interactions with the prehydrated sorbents, as compared with the sorbent samples in phenol-free atmosphere at the same RH, showed, for the first time, a sigmoid kinetics of phenol-induced mass uptake typical for second-order autocatalytic reactions. The apparent rate constants were similar for all the sorbents, RHs and phenol activities studied. A significant part of sorbed phenol resisted extraction, which was attributed to its abiotic oxidative coupling. Phenol uptake by peat and clay soils was also associated with a significant enhancement of water retention. The delayed development of the sigmoidal kinetics in phenol-water uptake demonstrates that long-run abiotic interactions of water-organic vapor with soil may be overlooked, based on short-term examination.

Giant Extraluminal Leiomyoma of the Colon: Rare Cause of Symptomatic Pelvic Mass

PubMed Central

Sagnotta, Andrea; Sparagna, Alessandra; Uccini, Stefania; Mercantini, Paolo

2015-01-01

Leiomyomas (LMs) may appear throughout the entire gastrointestinal tract but are rarely seen in the colon-rectum and only 5 of those measured greater than 15 cm in diameter. Pain and palpable abdominal mass are the most common symptoms. Surgical resection is the treatment of choice for most LMs. We here describe a case of a 46-year-old woman who presented with a 3-month history of abdominal pain associated with worsening constipation and abdominal distension. A pelvic solid, polylobulate, left-sided mass was noted on examination. Preoperative findings revealed a dishomogeneous sigmoid mass with calcified spots compressing small intestine and bladder. At laparotomy, a large polylobulate and well-circumscribed mass arising from the descending colon mesentery and displacing small intestine, uterus, and ovaries. A segmental colon resection was performed. An extraluminal 18- × 12- × 5-cm paucicellular sigmoid colon leiomyoma was histologically diagnosed. Our case is one of the few giant (>15 cm) sigmoid colon LMs reported in the literature. Although rare and benign in nature, LMs of the colon can cause life-threatening complications that could require emergency treatment and they should be included in the differential diagnosis of large abdominopelvic masses. Follow-up after surgery is necessary for tumors with any atypia or mitotic activity. PMID:26011198

Giant extraluminal leiomyoma of the colon: rare cause of symptomatic pelvic mass.

PubMed

Sagnotta, Andrea; Sparagna, Alessandra; Uccini, Stefania; Mercantini, Paolo

2015-05-01

Leiomyomas (LMs) may appear throughout the entire gastrointestinal tract but are rarely seen in the colon-rectum and only 5 of those measured greater than 15 cm in diameter. Pain and palpable abdominal mass are the most common symptoms. Surgical resection is the treatment of choice for most LMs. We here describe a case of a 46-year-old woman who presented with a 3-month history of abdominal pain associated with worsening constipation and abdominal distension. A pelvic solid, polylobulate, left-sided mass was noted on examination. Preoperative findings revealed a dishomogeneous sigmoid mass with calcified spots compressing small intestine and bladder. At laparotomy, a large polylobulate and well-circumscribed mass arising from the descending colon mesentery and displacing small intestine, uterus, and ovaries. A segmental colon resection was performed. An extraluminal 18- × 12- × 5-cm paucicellular sigmoid colon leiomyoma was histologically diagnosed. Our case is one of the few giant (>15 cm) sigmoid colon LMs reported in the literature. Although rare and benign in nature, LMs of the colon can cause life-threatening complications that could require emergency treatment and they should be included in the differential diagnosis of large abdominopelvic masses. Follow-up after surgery is necessary for tumors with any atypia or mitotic activity.

Incidence and Risk Factors for Sigmoid Venous Thrombosis Following CPA Tumor Resection.

PubMed

Shew, Matthew; Kavookjian, Hannah; Dahlstrom, Kelly; Muelleman, Thomas; Lin, James; Camarata, Paul; Ledbetter, Luke N; Staecker, Hinrich

2018-06-01

Our primary aim was to determine the incidence of sigmoid venous thrombosis (SVT) and determine risks factors and sequelae of SVT following cerebellopontine angle tumor resection. Retrospective cohort study. Academic tertiary care hospital. Patients over 18 years of age who underwent resection of cerebellopontine angle meningioma or vestibular schwannoma from January 2005 to April 2016 who had postoperative magnetic resonance imaging. Diagnostic. Incidence of postoperative sigmoid venous thrombosis (SVT) from official radiology reports was compared with retrospective imaging review by our institutional neuroradiologists. Data collected included age, length of stay, body mass index, surgical approach, and postoperative complications. A total of 127 patients were identified. Official radiology reads significantly underreported the incidence of postoperative SVT compared with retrospective review by our institutional neuroradiologist for patients who underwent routine postoperative imaging (n = 4 [3.1%] versus n = 22 [17.3%]; p < 0.001). There was a statistical trend toward increased risk for thrombosis in patients undergoing translabyrinthine and staged resection that did not reach significance (p = 0.068). Cerebrospinal fluid (CSF) leak incidence in patients with thrombosis was significantly increased (n = 9 [37.5%] versus n = 13 [12.6%]; p = 0.007). When controlling for approach, the presence of thrombus was associated with a more then three-fold increase in odds of CSF leak (OR = 3.28, 95% CI: 1.12-9.48, p = 0.030). There was no correlation between SVT and age (p = 0.788), body mass index (p = 0.686), length of stay (p = 0.733), preoperative tumor size (p = 0.555), or increased postoperative ICP (p = 0.645). Only one patient was symptomatic from sigmoid thrombosis compared with 21 who were not. Incidence of SVT is significantly underreported and may predispose patients to increase risk for CSF leak. Staged and translabyrinthine approaches demonstrate an increased trend toward thrombosis risk. Our findings suggest it may not be necessary to treat asymptomatic SVT.

[Laparoscopic "fast-track" sigmoidectomy for diverticulitis disease in Germany. Results of a prospective quality assurance program].

PubMed

Tsilimparis, N; Haase, O; Wendling, P; Kipfmüller, K; Schmid, M; Engemann, R; Schwenk, W

2010-09-01

The natural course of sigmoid colon diverticulitis during conservative therapy and the assessment of the perioperative morbidity after sigmoid colon resection are differently evaluated by surgeons and gastroenterologists. The "fast-track" rehabilitation accelerates the reconvalescence and reduces the rate of postoperative general complications after colorectal surgery. The results of the laparoscopic "Fast-track" sigmoidectomy should be examined within a quality assurance program to better evaluate the perioperative risks following surgical management of diverticulitis. A prospective data collection within the voluntary quality assurance program "fast-track" Kolon II was performed. All participating clinics agreed on a multimodal, evidence-based standard perioperative treatment in terms of a "fast-track" rehabilitation for elective operations for sigmoid diverticulitis. Data from 846 patients undergoing laparoscopic "fast-track" sigmoid colon resection in 23 surgical departments in Germany were collected and evaluated. The mean age of the patients was 63 years (range 23 - 91). 203 patients (24 %) had severe co-morbidities (ASA classification III - IV). A conversion to conventional open surgery was necessary in 51 cases (6 %). Complications occurred in 93 patients (11 %). 76 patients suffered a surgical complication (8.9 %) and 32 patients (3.8 %) a general complication. Two patients died postoperatively due to multi-organ failure following anastomotic leaks. The patients took solid food in median on day 1 after surgery (range, 0 - 5) and passed stool on day 2 (range, 0 - 22). Predefined discharge criteria (free of pain on oral medication, normal oral feeding, stool) were met on day 4 (range, 1 - 58) and the patients were discharged on day 7 (range, 3 - 72). The 30-day re-admission rate was 3.9 %. Patients undergoing laparoscopic "fast-track" sigmoidectomy had a low rate of general complications and had a rapid reconvalescence with a short postoperative in-patient treatment as documented in a german quality assurance program. Copyright Georg Thieme Verlag KG Stuttgart . New York.

Comparative dosimetric and radiobiological assessment among a nonstandard RapidArc, standard RapidArc, classical intensity-modulated radiotherapy, and 3D brachytherapy for the treatment of the vaginal vault in patients affected by gynecologic cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pedicini, Piernicola, E-mail: ppiern@libero.it; Caivano, Rocchina; Fiorentino, Alba

2012-01-01

To evaluate a nonstandard RapidArc (RA) modality as alternative to high-dose-rate brachytherapy (HDR-BRT) or IMRT treatments of the vaginal vault in patients with gynecological cancer (GC). Nonstandard (with vaginal applicator) and standard (without vaginal applicator) RapidArc plans for 27 women with GC were developed to compare with HDR-BRT and IMRT. Dosimetric and radiobiological comparison were performed by means of dose-volume histogram and equivalent uniform dose (EUD) for planning target volume (PTV) and organs at risk (OARs). In addition, the integral dose and the overall treatment times were evaluated. RA, as well as IMRT, results in a high uniform dose onmore » PTV compared with HDR-BRT. However, the average of EUD for HDR-BRT was significantly higher than those with RA and IMRT. With respect to the OARs, standard RA was equivalent of IMRT but inferior to HDR-BRT. Furthermore, nonstandard RA was comparable with IMRT for bladder and sigmoid and better than HDR-BRT for the rectum because of a significant reduction of d{sub 2cc}, d{sub 1cc}, and d{sub max} (p < 0.01). Integral doses were always higher than HDR-BRT, although the values were very low. Delivery times were about the same and more than double for HDR-BRT compared with IMRT and RA, respectively. In conclusion, the boost of dose on vaginal vault in patients affected by GC delivered by a nonstandard RA technique was a reasonable alternative to the conventional HDR-BRT because of a reduction of delivery time and rectal dose at substantial comparable doses for the bladder and sigmoid. However HDR-BRT provides better performance in terms of PTV coverage as evidenced by a greater EUD.« less

SU-D-213AB-05: Commissioning a CT Compatible LDR T&O Applicator Using Analytical Calculation with ID and 3D Dosimetry.

PubMed

Adamson, J; Newton, J; Steffey, B; Cai, J; Adamovics, J; Oldham, M; Chino, J; Craciunescu, O

2012-06-01

To determine the characteristics of a new commercially available CT-compatible LDR Tandem and Ovoid (T&O) applicator using 3D dosimetry. We characterized source attenuation through the asymmetric gold shielding in the buckets by measuring dose with diode and 3D dosimetry and compared to an analytical line integral calculation. For 3D dosimetry, a cylindrical PRESAGE dosimeter (9.5cm diameter, 9.2cm height) with a central 6mm channel bored for source placement was scanned with the Duke Large field of view Optical CT-Scanner (DLOS) before and after delivering a nominal 7.7Gy at a distance of 1 cm using a Cs-137 source loaded in the bucket. The optical CT scan time lasted approximately 15 minutes during which 720 projections were acquired at 0.5° increments, anda 3D dose distribution was reconstructed with a 0.5mm 3 isotropic voxel size. The 3D dose distribution was applied to a CT-based T&O implant to determine effect of ovoid shielding on the dose delivered to ICRU 38 Point A as well as D2cc of the bladder, rectum, bowel, and sigmoid. Dose transmission through the gold shielding at a radial distance of 1-3cm from midplane of the source was 86.6%, 86.1, and 87.0% for analytical calculation, diode, and 3D dosimetry, respectively. For the gold shielding of the bucket, dose transmission calculated using the 3D dosimetrymeasurement was found to be lowest at oblique angles from the bucket witha minimum of ∼51%. For the patient case, attenuation from the buckets leadto a decrease in average Point A dose of ∼4% and decrease in D2cc to bladder, rectum, sigmoid, and bowel of 2%, 15%, 2%, and 7%, respectively. The measured 3D dose distribution provided unique insight to the dosimetry and shielding characteristics of the investigated applicator, the technique for which can be applied to commissioning of other brachytherapy applicators. John Adamovics is the owner of Heuris Pharma LLC. Partially supported by NIH Grant R01 CA100835-01. © 2012 American Association of Physicists in Medicine.

[APPLICATION OF BUTTERFLY SHAPED LOCKING COMPRESSION PLATE IN COMPLEX DISTAL RADIUS FRACTURES].

PubMed

Jiang, Zongyuan; Ma, Tao; Xia, Jiang; Hu, Caizhi; Xu, Lei

2014-06-01

To investigate the effectiveness of butterfly shaped locking compression plate for the treatment of complex distal radius fractures. Between June 2011 and January 2013, 20 cases of complex distal radius fractures were treated with butterfly shaped locking compression plate fixation. There were 11 males and 9 females with an average age of 54 years (range, 25-75 years). Injury was caused by falling in 10 cases, by traffic accident in 7 cases, and by falling from height in 3 cases. All of fractures were closed. According to AO classification system, there were 8 cases of type C1, 8 cases of type C2, and 4 cases of type C3. Of them, 9 cases had radial styloid process fracture, 4 cases had sigmoid notch fracture, and 7 cases had both radial styloid process fracture and sigmoid notch fracture. The mean interval between injury and operation was 5.2 days (range, 3-15 days). All incisions healed by first intention; no complications of infection and necrosis occurred. All cases were followed up 14 months on average (range, 10-22 months). All factures healed after 9.3 weeks on average (range, 6-11 weeks). No complications such as displacement of fracture, joint surface subsidence, shortening of the radius, and carpal tunnel syndrome were found during follow-up. At last follow-up, the mean palmar tilt angle was 10.2° (range, 7-15°), and the mean ulnar deviation angle was 21.8° (range, 17-24°). The mean range of motion of the wrist was 45.3° (range, 35-68°) in dorsal extension, 53.5° (range, 40-78°) in palmar flexion, 19.8° (range, 12-27°) in radial inclination, 26.6° (range, 18-31°) in ulnar inclination, 70.2° (range, 45-90°) in pronation, and 68.4° (range, 25-88°) in supination. According to the Dienst scoring system, the results were excellent in 8 cases, good in 10 cases, and fair in 2 cases, and the excellent and good rate was 90%. Treatment of complex distal radius fractures with butterfly shaped locking compression plate can reconstruct normal anatomic structures, especially for radial styloid process and sigmoid notch fractures, and it can get good functional recovery of the wrist and the distal radioulnar joint.

Optimization of autoregressive, exogenous inputs-based typhoon inundation forecasting models using a multi-objective genetic algorithm

NASA Astrophysics Data System (ADS)

Ouyang, Huei-Tau

2017-07-01

Three types of model for forecasting inundation levels during typhoons were optimized: the linear autoregressive model with exogenous inputs (LARX), the nonlinear autoregressive model with exogenous inputs with wavelet function (NLARX-W) and the nonlinear autoregressive model with exogenous inputs with sigmoid function (NLARX-S). The forecast performance was evaluated by three indices: coefficient of efficiency, error in peak water level and relative time shift. Historical typhoon data were used to establish water-level forecasting models that satisfy all three objectives. A multi-objective genetic algorithm was employed to search for the Pareto-optimal model set that satisfies all three objectives and select the ideal models for the three indices. Findings showed that the optimized nonlinear models (NLARX-W and NLARX-S) outperformed the linear model (LARX). Among the nonlinear models, the optimized NLARX-W model achieved a more balanced performance on the three indices than the NLARX-S models and is recommended for inundation forecasting during typhoons.

Artificial neural network with backpropagation learning to predict mean monthly total ozone in Arosa, Switzerland

NASA Astrophysics Data System (ADS)

Chattopadhyay, Surajit; Bandyopadhyay, Goutami

2007-01-01

Present study deals with the mean monthly total ozone time series over Arosa, Switzerland. The study period is 1932-1971. First of all, the total ozone time series has been identified as a complex system and then Artificial Neural Networks models in the form of Multilayer Perceptron with back propagation learning have been developed. The models are Single-hidden-layer and Two-hidden-layer Perceptrons with sigmoid activation function. After sequential learning with learning rate 0.9 the peak total ozone period (February-May) concentrations of mean monthly total ozone have been predicted by the two neural net models. After training and validation, both of the models are found skillful. But, Two-hidden-layer Perceptron is found to be more adroit in predicting the mean monthly total ozone concentrations over the aforesaid period.

Kinetic modeling and long-term test-retest reproducibility of the mGluR5 PET tracer 18F-FPEB in human brain.

PubMed

Leurquin-Sterk, Gil; Postnov, Andrey; de Laat, Bart; Casteels, Cindy; Celen, Sofie; Crunelle, Cleo L; Bormans, Guy; Koole, Michel; Van Laere, Koen

2016-04-01

(18)F-FPEB is a promising PET tracer for studying the metabotropic glutamate subtype 5 receptor (mGluR5) expression in neuropsychiatric disorders. To assess the potential of (18)F-FPEB for longitudinal mGluR5 evaluation in patient studies, we evaluated the long-term test-retest reproducibility using various kinetic models in the human brain. Nine healthy volunteers underwent consecutive scans separated by a 6-month period. Dynamic PET was combined with arterial sampling and radiometabolite analysis. Total distribution volume (V(T)) and nondisplaceable binding potential (BP(ND)) were derived from a two-tissue compartment model without constraints (2TCM) and with constraining the K(1)/k(2) ratio to the value of either cerebellum (2TCM-CBL) or pons (2TCM-PONS). The effect of fitting different functions to the tracer parent fractions and reducing scan duration were assessed. Regional absolute test-retest variability (aTRV), coefficient of repeatability (CR) and intraclass correlation coefficient (ICC) were computed. The 2TCM-CBL showed best fits. The mean 6-month aTRV of V(T) ranged from 8 to 13% (CR < 25%) with ICC > 0.6 for all kinetic models. BPND from 2TCM-CBL with a sigmoid fit for the parent fractions showed the best reproducibility, with aTRV ≤ 7% (CR < 16%) and ICC > 0.9 in most regions. Reducing the scan duration from 90 to 60 min did not affect reproducibility. These results demonstrate for the first time that (18)F-FPEB brain PET has good long-term reproducibility, therefore validating its use to monitor mGluR5 expression in longitudinal clinical studies. We suggest a 2TCM-CBL with fitting a sigmoid function to the parent fractions to be optimal for this tracer. © 2016 Wiley Periodicals, Inc.

Revisiting colostomy irrigation: a viable option for persons with permanent descending and sigmoid colostomies.

PubMed

Kent, Dea J; Arnold Long, Mary; Bauer, Carole

2015-01-01

Colostomy irrigation (CI) is the regular irrigation of the bowel for persons with a permanent colostomy of the descending or sigmoid colon. Although this technique was first described in the 1920s, a recent study of 985 WOC nurses found that almost half (47%) do not routinely teach CI to persons with colostomies. In a systematic review (Evidence-Based Report Card) published in this issue of the Journal, we summarized current best evidence concerning the effect of CI on bowel function and found that irrigation reduces the frequency of bowel elimination episodes and allows some patients to reduce or eliminate ongoing use of a pouching system. This article describes techniques for teaching CI and discussed additional findings associated with CI.

Unusual presentation of pheochromocytoma with ischemic sigmoid colitis and stenosis.

PubMed

Tan, Florence; Thai, Ah Chuan; Cheah, Wei Keat; Mukherjee, J J

2009-10-01

A 45-year-old woman with poorly controlled hypertension and diabetes mellitus presented with left iliac fossa pain, constipation alternating with diarrhea, and weight loss. She had been diagnosed with idiopathic cardiomyopathy five years previously. Echocardiogram had shown a left ventricular ejection fraction (LVEF) of 35%; coronary angiogram was normal. Colonoscopy revealed sigmoid colitis with stenosis. Abdominal computed tomography revealed a 5 cm right adrenal tumor. Twenty-four hour urinary free catecholamines and fractionated metanephrine excretion values were elevated, confirming pheochromocytoma. Her colitis resolved after one month of adrenergic blockade. Repeat echocardiogram showed improvement of LVEF to 65%. After laparoscopic right adrenalectomy, the patient's hypertension resolved, and diabetic control improved. Timely management avoided further morbidity and potential mortality in our patient.

High-Flow Vascular Malformation in the Sigmoid Mesentery Successfully Treated with a Combination of Transarterial and Transvenous Embolization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamo, Minobu, E-mail: kamomino@luke.ac.jp; Yagihashi, Kunihiro; Okamoto, Takeshi

Mesenteric high-flow vascular malformation can cause various clinical symptoms and demand specific therapeutic interventions owing to its peculiar hemodynamics. We report a case of high-flow vascular malformation in the sigmoid mesentery which presented with ischemic colitis. The main trunk of the inferior mesenteric vein was occluded. After partially effective transarterial embolization, transvenous embolization was performed using a microballoon catheter advanced to the venous component of the lesion via the marginal vein. Complete occlusion of the lesion was achieved. Combination of transarterial and transvenous embolization may allow us to apply endovascular treatment to a wider variety of high-flow lesions in themore » area and possibly avoid the bowel resection.« less

Bernoulli-Langevin Wind Speed Model for Simulation of Storm Events

NASA Astrophysics Data System (ADS)

Fürstenau, Norbert; Mittendorf, Monika

2016-12-01

We present a simple nonlinear dynamics Langevin model for predicting the instationary wind speed profile during storm events typically accompanying extreme low-pressure situations. It is based on a second-degree Bernoulli equation with δ-correlated Gaussian noise and may complement stationary stochastic wind models. Transition between increasing and decreasing wind speed and (quasi) stationary normal wind and storm states are induced by the sign change of the controlling time-dependent rate parameter k(t). This approach corresponds to the simplified nonlinear laser dynamics for the incoherent to coherent transition of light emission that can be understood by a phase transition analogy within equilibrium thermodynamics [H. Haken, Synergetics, 3rd ed., Springer, Berlin, Heidelberg, New York 1983/2004.]. Evidence for the nonlinear dynamics two-state approach is generated by fitting of two historical wind speed profiles (low-pressure situations "Xaver" and "Christian", 2013) taken from Meteorological Terminal Air Report weather data, with a logistic approximation (i.e. constant rate coefficients k) to the solution of our dynamical model using a sum of sigmoid functions. The analytical solution of our dynamical two-state Bernoulli equation as obtained with a sinusoidal rate ansatz k(t) of period T (=storm duration) exhibits reasonable agreement with the logistic fit to the empirical data. Noise parameter estimates of speed fluctuations are derived from empirical fit residuals and by means of a stationary solution of the corresponding Fokker-Planck equation. Numerical simulations with the Bernoulli-Langevin equation demonstrate the potential for stochastic wind speed profile modeling and predictive filtering under extreme storm events that is suggested for applications in anticipative air traffic management.

A comparison of methods of fitting several models to nutritional response data.

PubMed

Vedenov, D; Pesti, G M

2008-02-01

A variety of models have been proposed to fit nutritional input-output response data. The models are typically nonlinear; therefore, fitting the models usually requires sophisticated statistical software and training to use it. An alternative tool for fitting nutritional response models was developed by using widely available and easier-to-use Microsoft Excel software. The tool, implemented as an Excel workbook (NRM.xls), allows simultaneous fitting and side-by-side comparisons of several popular models. This study compared the results produced by the tool we developed and PROC NLIN of SAS. The models compared were the broken line (ascending linear and quadratic segments), saturation kinetics, 4-parameter logistics, sigmoidal, and exponential models. The NRM.xls workbook provided results nearly identical to those of PROC NLIN. Furthermore, the workbook successfully fit several models that failed to converge in PROC NLIN. Two data sets were used as examples to compare fits by the different models. The results suggest that no particular nonlinear model is necessarily best for all nutritional response data.

The biasing of figure-ground assignment by shading cues for objects and faces in prosopagnosia.

PubMed

Hefter, Rebecca; Jerskey, Beth A; Barton, Jason J S

2008-01-01

Prosopagnosia is defined by impaired recognition of the identity of specific faces. Whether the perception of faces at the categorical level (recognizing that a face is a face) is also impaired to a lesser degree is unclear. We examined whether prosopagnosia is associated with impaired detection of facial contours in a bistable display, by testing a series of five prosopagnosic patients on a variation of Rubin's vase illusion, in which shading was introduced to bias perception towards either the face or the vase. We also included a control bistable display in which a disc or an aperture were the two possible percepts. With the control disc/aperture test, prosopagnosic patients did not generate a normal sigmoid function, but a U-shaped function, indicating that they perceived the shading but had difficulty in using the shading to make the appropriate figure-ground assignment. While controls still generated a sigmoid function for the vase/face test, prosopagnosic patients showed a severe impairment in using shading to make consistent perceptual assignments. We conclude that prosopagnosic patients have difficulty in using shading to segment figures from background correctly, particularly with complex stimuli like faces. This suggests that a subtler defect in face categorization accompanies their severe defect in face identification, consistent with predictions of computational models and recent data from functional imaging.

The critical distance in laser-induced plasmas: an operative definition

NASA Astrophysics Data System (ADS)

Delle Side, D.; Giuffreda, E.; Nassisi, V.

2016-05-01

We propose a method to estimate a precise value for the critical distance Lcr after which three-body recombination stops to produce charge losses in an expanding laser-induced plasma. We show in particular that the total charge collected has a ``reversed sigmoid'' shape as a function of the target-to-detector distance. Fitting the total charge data with a logistic related function, we could consider as Lcr the intercept of the tangent to this curve in its inflection point. Furthermore, this value scales well with theoretical predictions. From the application point of view, this could be of great practical interest, since it provide a reliable way to precisely determine the geometry of the extraction system in Laser Ion Sources.

Fabrication and Characterization of Ultrathin-ring Electrodes for Pseudo-steady-state Amperometric Detection.

PubMed

Kitazumi, Yuki; Hamamoto, Katsumi; Noda, Tatsuo; Shirai, Osamu; Kano, Kenji

2015-01-01

The fabrication of ultrathin-ring electrodes with a diameter of 2 mm and a thickness of 100 nm is established. The ultrathin-ring electrodes provide a large density of pseudo-steady-state currents, and realize pseudo-steady-state amperometry under quiescent conditions without a Faraday cage. Under the limiting current conditions, the current response at the ultrathin-ring electrode can be well explained by the theory of the microband electrode response. Cyclic voltammograms at the ultrathin-ring electrode show sigmoidal characteristics with some hysteresis. Numerical simulation reveals that the hysteresis can be ascribed to the time-dependence of pseudo-steady-state current. The performance of amperometry with the ultrathin-ring electrode has been verified in its application to redox enzyme kinetic measurements.

Exposure–response model for sibutramine and placebo: suggestion for application to long-term weight-control drug development

PubMed Central

Han, Seunghoon; Jeon, Sangil; Hong, Taegon; Lee, Jongtae; Bae, Soo Hyeon; Park, Wan-su; Park, Gab-jin; Youn, Sunil; Jang, Doo Yeon; Kim, Kyung-Soo; Yim, Dong-Seok

2015-01-01

No wholly successful weight-control drugs have been developed to date, despite the tremendous demand. We present an exposure–response model of sibutramine mesylate that can be applied during clinical development of other weight-control drugs. Additionally, we provide a model-based evaluation of sibutramine efficacy. Data from a double-blind, randomized, placebo-controlled, multicenter study were used (N=120). Subjects in the treatment arm were initially given 8.37 mg sibutramine base daily, and those who lost <2 kg after 4 weeks’ treatment were escalated to 12.55 mg. The duration of treatment was 24 weeks. Drug concentration and body weight were measured predose and at 4 weeks, 8 weeks, and 24 weeks after treatment initiation. Exposure and response to sibutramine, including the placebo effect, were modeled using NONMEM 7.2. An asymptotic model approaching the final body weight was chosen to describe the time course of weight loss. Extent of weight loss was described successfully using a sigmoidal exposure–response relationship of the drug with a constant placebo effect in each individual. The placebo effect was influenced by subjects’ sex and baseline body mass index. Maximal weight loss was predicted to occur around 1 year after treatment initiation. The difference in mean weight loss between the sibutramine (daily 12.55 mg) and placebo groups was predicted to be 4.5% in a simulation of 1 year of treatment, with considerable overlap of prediction intervals. Our exposure–response model, which included the placebo effect, is the first example of a quantitative model that can be used to predict the efficacy of weight-control drugs. Similar approaches can help decision-making during clinical development of novel weight-loss drugs. PMID:26392753

Exposure-response model for sibutramine and placebo: suggestion for application to long-term weight-control drug development.

PubMed

Han, Seunghoon; Jeon, Sangil; Hong, Taegon; Lee, Jongtae; Bae, Soo Hyeon; Park, Wan-su; Park, Gab-jin; Youn, Sunil; Jang, Doo Yeon; Kim, Kyung-Soo; Yim, Dong-Seok

2015-01-01

No wholly successful weight-control drugs have been developed to date, despite the tremendous demand. We present an exposure-response model of sibutramine mesylate that can be applied during clinical development of other weight-control drugs. Additionally, we provide a model-based evaluation of sibutramine efficacy. Data from a double-blind, randomized, placebo-controlled, multicenter study were used (N=120). Subjects in the treatment arm were initially given 8.37 mg sibutramine base daily, and those who lost <2 kg after 4 weeks' treatment were escalated to 12.55 mg. The duration of treatment was 24 weeks. Drug concentration and body weight were measured predose and at 4 weeks, 8 weeks, and 24 weeks after treatment initiation. Exposure and response to sibutramine, including the placebo effect, were modeled using NONMEM 7.2. An asymptotic model approaching the final body weight was chosen to describe the time course of weight loss. Extent of weight loss was described successfully using a sigmoidal exposure-response relationship of the drug with a constant placebo effect in each individual. The placebo effect was influenced by subjects' sex and baseline body mass index. Maximal weight loss was predicted to occur around 1 year after treatment initiation. The difference in mean weight loss between the sibutramine (daily 12.55 mg) and placebo groups was predicted to be 4.5% in a simulation of 1 year of treatment, with considerable overlap of prediction intervals. Our exposure-response model, which included the placebo effect, is the first example of a quantitative model that can be used to predict the efficacy of weight-control drugs. Similar approaches can help decision-making during clinical development of novel weight-loss drugs.

On the complexity of neural network classifiers: a comparison between shallow and deep architectures.

PubMed

Bianchini, Monica; Scarselli, Franco

2014-08-01

Recently, researchers in the artificial neural network field have focused their attention on connectionist models composed by several hidden layers. In fact, experimental results and heuristic considerations suggest that deep architectures are more suitable than shallow ones for modern applications, facing very complex problems, e.g., vision and human language understanding. However, the actual theoretical results supporting such a claim are still few and incomplete. In this paper, we propose a new approach to study how the depth of feedforward neural networks impacts on their ability in implementing high complexity functions. First, a new measure based on topological concepts is introduced, aimed at evaluating the complexity of the function implemented by a neural network, used for classification purposes. Then, deep and shallow neural architectures with common sigmoidal activation functions are compared, by deriving upper and lower bounds on their complexity, and studying how the complexity depends on the number of hidden units and the used activation function. The obtained results seem to support the idea that deep networks actually implements functions of higher complexity, so that they are able, with the same number of resources, to address more difficult problems.

Effects of disulfide bridges and backbone connectivity on water sorption by protein matrices.

PubMed

Kim, Sang Beom; Singh, Rakesh S; Paul, Prem K C; Debenedetti, Pablo G

2017-08-11

Understanding the water sorption behavior of protein powders is important in applications such as the preservation of protein-based pharmaceuticals. Most globular proteins exhibit a characteristic sigmoidal water adsorption isotherm at ambient conditions. However, it is not well understood how water sorption behavior is influenced by intrinsic factors that are related to structural properties of proteins. We investigate computationally how structural constraints on proteins influence the water sorption isotherms of amorphous protein powders. Specifically, we study the effects of non-local disulfide linkages and backbone connectivity using pheromone ER-23 and lysozyme as model proteins. We find that non-local disulfide linkages can significantly restrict structural changes during hydration and dehydration, and this in turn greatly reduces the extent of hysteresis between the adsorption and desorption branches. Upon removing the backbone connectivity by breaking all peptide bonds in lysozyme, we find that the hysteresis shifts towards the lower humidity regime, and the water uptake capacity is significantly enhanced. We attribute these changes to the higher aggregation propensity of the constraint-free amino acids in dehydrated condition, and the formation of a spanning water network at high hydration levels.

THE CONTRACTION OF OVERLYING CORONAL LOOP AND THE ROTATING MOTION OF A SIGMOID FILAMENT DURING ITS ERUPTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, X. L.; Qu, Z. Q.; Xue, Z. K.

We present an observation of overlying coronal loop contraction and rotating motion of the sigmoid filament during its eruption on 2012 May 22 observed by the Solar Dynamics Observatory (SDO). Our results show that the twist can be transported into the filament from the lower atmosphere to the higher atmosphere. The successive contraction of the coronal loops was due to a suddenly reduced magnetic pressure underneath the filament, which was caused by the rising of the filament. Before the sigmoid filament eruption, there was a counterclockwise flow in the photosphere at the right feet of the filament and the contractionmore » loops and a convergence flow at the left foot of the filament. The hot and cool materials have inverse motion along the filament before the filament eruption. Moreover, two coronal loops overlying the filament first experienced brightening, expansion, and contraction successively. At the beginning of the rising and rotation of the left part of the filament, the second coronal loop exhibited rapid contraction. The top of the second coronal loop also showed counterclockwise rotation during the contraction process. After the contraction of the second loop, the left part of the filament rotated counterclockwise and expanded toward the right of NOAA AR 11485. During the filament expansion, the right part of the filament also exhibited counterclockwise rotation like a tornado.« less

The Contraction of Overlying Coronal Loop and the Rotating Motion of a Sigmoid Filament during Its Eruption

NASA Astrophysics Data System (ADS)

Yan, X. L.; Pan, G. M.; Liu, J. H.; Qu, Z. Q.; Xue, Z. K.; Deng, L. H.; Ma, L.; Kong, D. F.

2013-06-01

We present an observation of overlying coronal loop contraction and rotating motion of the sigmoid filament during its eruption on 2012 May 22 observed by the Solar Dynamics Observatory (SDO). Our results show that the twist can be transported into the filament from the lower atmosphere to the higher atmosphere. The successive contraction of the coronal loops was due to a suddenly reduced magnetic pressure underneath the filament, which was caused by the rising of the filament. Before the sigmoid filament eruption, there was a counterclockwise flow in the photosphere at the right feet of the filament and the contraction loops and a convergence flow at the left foot of the filament. The hot and cool materials have inverse motion along the filament before the filament eruption. Moreover, two coronal loops overlying the filament first experienced brightening, expansion, and contraction successively. At the beginning of the rising and rotation of the left part of the filament, the second coronal loop exhibited rapid contraction. The top of the second coronal loop also showed counterclockwise rotation during the contraction process. After the contraction of the second loop, the left part of the filament rotated counterclockwise and expanded toward the right of NOAA AR 11485. During the filament expansion, the right part of the filament also exhibited counterclockwise rotation like a tornado.

Temperature Effects on Force and Actin⁻Myosin Interaction in Muscle: A Look Back on Some Experimental Findings.

PubMed

Ranatunga, K W

2018-05-22

Observations made in temperature studies on mammalian muscle during force development, shortening, and lengthening, are re-examined. The isometric force in active muscle goes up substantially on warming from less than 10 °C to temperatures closer to physiological (>30 °C), and the sigmoidal temperature dependence of this force has a half-maximum at ~10 °C. During steady shortening, when force is decreased to a steady level, the sigmoidal curve is more pronounced and shifted to higher temperatures, whereas, in lengthening muscle, the curve is shifted to lower temperatures, and there is a less marked increase with temperature. Even with a small rapid temperature-jump (T-jump), force in active muscle rises in a definitive way. The rate of tension rise is slower with adenosine diphosphate (ADP) and faster with increased phosphate. Analysis showed that a T-jump enhances an early, pre-phosphate release step in the acto-myosin (crossbridge) ATPase cycle, thus inducing a force-rise. The sigmoidal dependence of steady force on temperature is due to this endothermic nature of crossbridge force generation. During shortening, the force-generating step and the ATPase cycle are accelerated, whereas during lengthening, they are inhibited. The endothermic force generation is seen in different muscle types (fast, slow, and cardiac). The underlying mechanism may involve a structural change in attached myosin heads and/or their attachments on heat absorption.

Temperature Effects on Force and Actin–Myosin Interaction in Muscle: A Look Back on Some Experimental Findings

PubMed Central

Ranatunga, K. W.

2018-01-01

Observations made in temperature studies on mammalian muscle during force development, shortening, and lengthening, are re-examined. The isometric force in active muscle goes up substantially on warming from less than 10 °C to temperatures closer to physiological (>30 °C), and the sigmoidal temperature dependence of this force has a half-maximum at ~10 °C. During steady shortening, when force is decreased to a steady level, the sigmoidal curve is more pronounced and shifted to higher temperatures, whereas, in lengthening muscle, the curve is shifted to lower temperatures, and there is a less marked increase with temperature. Even with a small rapid temperature-jump (T-jump), force in active muscle rises in a definitive way. The rate of tension rise is slower with adenosine diphosphate (ADP) and faster with increased phosphate. Analysis showed that a T-jump enhances an early, pre-phosphate release step in the acto-myosin (crossbridge) ATPase cycle, thus inducing a force-rise. The sigmoidal dependence of steady force on temperature is due to this endothermic nature of crossbridge force generation. During shortening, the force-generating step and the ATPase cycle are accelerated, whereas during lengthening, they are inhibited. The endothermic force generation is seen in different muscle types (fast, slow, and cardiac). The underlying mechanism may involve a structural change in attached myosin heads and/or their attachments on heat absorption. PMID:29786656

Postoperative bacteriuria, pyuria and urinary tract infection in patients with an orthotopic sigmoid colon neobladder replacement.

PubMed

Shigemura, Katsumi; Tanaka, Kazushi; Arakawa, Soichi; Miyake, Hideaki; Fujisawa, Masato

2014-02-01

The purpose of this study is to investigate the prevalence of postoperative bacteriuria, pyuria and urine culture in patients with an orthotopic sigmoid colon neobladder replacement. Urine samples for bacteriuria, pyuria and urine culture, if necessary, were collected at 1, 3, 6, 9 and 12 months after surgery and the presence of blood culture and antibiotic-resistant strains, and their treatments on positive urine culture cases were investigated. Of 209 for bacteriuria and 207 for pyuria urine samples with evaluable data, 95 (45.5%) were positive for bacteriuria and 76 (36.7%) had pyuria (10 or more white blood cells per high-power field). Totally, 30 bacteria were isolated from urine culture of urinary tract infection (UTI) and Klebisiella pneumoniae, Escherichia coli, Staphylococcos aureus and Enterococcus spp. strains were representatively isolated. The incidence of pyuria significantly decreased over time (P=0.041) but that of bacteriuria did not (P=0.107). In them, there were six bacteria (20.7%) with antibiotic-resistant strains. The antibiotics used for their treatments representatively were levofloxacin in five cases, tazobactam/piperacillin in three cases and sulfamethoxazole/trimethoprim and cefepime, meropenem in two cases, respectively. In conclusion, these findings suggest that physicians taking care of sigmoid colon neobladder patients need to be aware of these high ratios of bacteriuria, pyuria and UTI, including bacteremia.

Plasma Composition in a Sigmoidal Anemone Active Region

NASA Astrophysics Data System (ADS)

Baker, D.; Brooks, D. H.; Démoulin, P.; van Driel-Gesztelyi, L.; Green, L. M.; Steed, K.; Carlyle, J.

2013-11-01

Using spectra obtained by the EUV Imaging Spectrometer (EIS) instrument onboard Hinode, we present a detailed spatially resolved abundance map of an active region (AR)-coronal hole (CH) complex that covers an area of 359'' × 485''. The abundance map provides first ionization potential (FIP) bias levels in various coronal structures within the large EIS field of view. Overall, FIP bias in the small, relatively young AR is 2-3. This modest FIP bias is a consequence of the age of the AR, its weak heating, and its partial reconnection with the surrounding CH. Plasma with a coronal composition is concentrated at AR loop footpoints, close to where fractionation is believed to take place in the chromosphere. In the AR, we found a moderate positive correlation of FIP bias with nonthermal velocity and magnetic flux density, both of which are also strongest at the AR loop footpoints. Pathways of slightly enhanced FIP bias are traced along some of the loops connecting opposite polarities within the AR. We interpret the traces of enhanced FIP bias along these loops to be the beginning of fractionated plasma mixing in the loops. Low FIP bias in a sigmoidal channel above the AR's main polarity inversion line, where ongoing flux cancellation is taking place, provides new evidence of a bald patch magnetic topology of a sigmoid/flux rope configuration.

Ten-Year Survival of a Patient Treated with Stereotactic Gamma Knife Radiosurgery for Brain Metastases from Colon Cancer with Ovarian and Lymph Node Metastases: A Case Report.

PubMed

Morinaga, Nobuhiro; Tanaka, Naritaka; Shitara, Yoshinori; Ishizaki, Masatoshi; Yoshida, Takatomo; Kouga, Hideaki; Wakabayashi, Kazuki; Fukuchi, Minoru; Tsunoda, Yoshiyuki; Kuwano, Hiroyuki

2016-01-01

Brain metastasis from colorectal cancer is infrequent and carries a poor prognosis. Herein, we present a patient alive 10 years after the identification of a first brain metastasis from sigmoid colon cancer. A 39-year-old woman underwent sigmoidectomy for sigmoid colon cancer during an emergency operation for pelvic peritonitis. The pathological finding was moderately differentiated adenocarcinoma. Eleven months after the sigmoidectomy, a metastatic lesion was identified in the left ovary. Despite local radiotherapy followed by chemotherapy, the left ovarian lesion grew, so resection of the uterus and bilateral ovaries was performed. Adjuvant chemotherapy with tegafur-uracil (UFT)/calcium folinate (leucovorin, LV) was initiated. Seven months after resection of the ovarian lesion, brain metastases appeared in the bilateral frontal lobes and were treated with stereotactic Gamma Knife radiosurgery. Cervical and mediastinal lymph node metastases were also diagnosed, and irradiation of these lesions was performed. After radiotherapy, 10 courses of oxaliplatin and infused fluorouracil plus leucovorin (FOLFOX) were administered. During FOLFOX administration, recurrent left frontal lobe brain metastasis was diagnosed and treated with stereotactic Gamma Knife radiosurgery. In this case, the brain metastases were well treated with stereotactic Gamma Knife radiosurgery, and the systemic disease arising from sigmoid colon cancer has been kept under control with chemotherapies, surgical resection, and radiotherapy.

A heuristic neural network initialization scheme for modeling nonlinear functions in engineering mechanics: continuous development

NASA Astrophysics Data System (ADS)

Pei, Jin-Song; Mai, Eric C.

2007-04-01

This paper introduces a continuous effort towards the development of a heuristic initialization methodology for constructing multilayer feedforward neural networks to model nonlinear functions. In this and previous studies that this work is built upon, including the one presented at SPIE 2006, the authors do not presume to provide a universal method to approximate arbitrary functions, rather the focus is given to the development of a rational and unambiguous initialization procedure that applies to the approximation of nonlinear functions in the specific domain of engineering mechanics. The applications of this exploratory work can be numerous including those associated with potential correlation and interpretation of the inner workings of neural networks, such as damage detection. The goal of this study is fulfilled by utilizing the governing physics and mathematics of nonlinear functions and the strength of the sigmoidal basis function. A step-by-step graphical procedure utilizing a few neural network prototypes as "templates" to approximate commonly seen memoryless nonlinear functions of one or two variables is further developed in this study. Decomposition of complex nonlinear functions into a summation of some simpler nonlinear functions is utilized to exploit this prototype-based initialization methodology. Training examples are presented to demonstrate the rationality and effciency of the proposed methodology when compared with the popular Nguyen-Widrow initialization algorithm. Future work is also identfied.

Bioremediation of oxytetracycline in seawater by living and dead biomass of the microalga Phaeodactylum tricornutum.

PubMed

Santaeufemia, Sergio; Torres, Enrique; Mera, Roi; Abalde, Julio

2016-12-15

Due to its use, a large amount of Oxytetracycline (OTC) is released into water, which has a detrimental impact on aquatic ecosystems and human health. Although there are different physicochemical methods (mainly photodegradation) to remove OTC, there is increasing interest in the use of bioremediation. The sorption characteristics of OTC using living and dead biomass of the microalga Phaeodactylum tricornutum have been investigated in this study. Kinetics, isotherms and maximum elimination capacity were tested and discussed. Kinetic studies showed that the OTC removal by living biomass followed a sigmoidal model. However, the dead biomass followed a pseudo-first order model. The living biomass showed higher efficiency than the dead biomass with maximum sorption capacities of 29.18mgg -1 and 4.54mgg -1 , respectively. Combination of living biomass and photodegradation under the culture conditions eliminated 13.2mgL -1 of OTC during 11h of culture and with an initial OTC concentration of 15mgL -1 . With an initial OTC concentration of 2.5mgL -1 , 97% of OTC was removed. This removal was mainly caused by bioremediation than by photodegradation. The results proved the potential practical application of the living P. tricornutum biomass for a low-cost and efficient removal of OTC from seawater. Copyright © 2016 Elsevier B.V. All rights reserved.

Flexible Sigmoidoscopy

MedlinePlus

... camera on one end, called a sigmoidoscope or scope, to look inside your rectum and lower colon, ... your rectum and into your sigmoid colon. The scope pumps air into your large intestine to give ...

A Comparison Study of an Active Region Eruptive Filament and a Neighboring Non-Eruptive Filament

NASA Astrophysics Data System (ADS)

Wu, S. T.; Jiang, C.; Feng, X. S.; Hu, Q.

2014-12-01

We perform a comparison study of an eruptive filament in the core region of AR 11283 and a nearby non-eruptive filament. The coronal magnetic field supporting these two filaments is extrapolated using our data-driven CESE-MHD-NLFFF code (Jiang et al. 2013, Jiang etal. 2014), which presents two magnetic flux ropes (FRs) in the same extrapolation box. The eruptive FR contains a bald-patch separatrix surface (BPSS) spatially co-aligned very well with a pre-eruption EUV sigmoid, which is consistent with the BPSS model for the coronal sigmoids. The numerically reproduced magnetic dips of the FRs match observations of the filaments strikingly well, which supports strongly the FR-dip model for filaments. The FR that supports the AR eruptive filament is much smaller (with a length of 3 Mm) compared with the large-scale FR holding the quiescent filament (with a length of 30 Mm). But the AR eruptive FR contains most of the magnetic free energy in the extrapolation box and holds a much higher magnetic energy density than the quiescent FR, because it resides along the main polarity inversion line (PIL) around sunspots with strong magnetic shear. Both the FRs are weakly twisted and cannot trigger kink instability. The AR eruptive FR is unstable because its axis reaches above a critical height for torus instability (TI), at which the overlying closed arcades can no longer confine the FR stably. To the contrary, the quiescent FR is firmly held down by its overlying field, as its axis apex is far below the TI threshold height. (This work is partially supported by NSF AGS-1153323 and 1062050)

A comparison study of a solar active-region eruptive filament and a neighboring non-eruptive filament

NASA Astrophysics Data System (ADS)

Jiang, Chao-Wei; Wu, Shi-Tsan; Feng, Xue-Shang; Hu, Qiang

2016-01-01

Solar active region (AR) 11283 is a very magnetically complex region and it has produced many eruptions. However, there exists a non-eruptive filament in the plage region just next to an eruptive one in the AR, which gives us an opportunity to perform a comparison analysis of these two filaments. The coronal magnetic field extrapolated using our CESE-MHD-NLFFF code reveals that two magnetic flux ropes (MFRs) exist in the same extrapolation box supporting these two filaments, respectively. Analysis of the magnetic field shows that the eruptive MFR contains a bald-patch separatrix surface (BPSS) cospatial very well with a pre-eruptive EUV sigmoid, which is consistent with the BPSS model for coronal sigmoids. The magnetic dips of the non-eruptive MFRs match Hα observation of the non-eruptive filament strikingly well, which strongly supports the MFR-dip model for filaments. Compared with the non-eruptive MFR/filament (with a length of about 200 Mm), the eruptive MFR/filament is much smaller (with a length of about 20 Mm), but it contains most of the magnetic free energy in the extrapolation box and holds a much higher free energy density than the non-eruptive one. Both the MFRs are weakly twisted and cannot trigger kink instability. The AR eruptive MFR is unstable because its axis reaches above a critical height for torus instability, at which the overlying closed arcades can no longer confine the MFR stably. On the contrary, the quiescent MFR is very firmly held by its overlying field, as its axis apex is far below the torus-instability threshold height. Overall, this comparison investigation supports that an MFR can exist prior to eruption and the ideal MHD instability can trigger an MFR eruption.

[Our current approach in the treatment of sigmoid colon volvulus].

PubMed

Taviloğlu, Korhan; Aydin, Erol; Ertekin, Cemalettin; Güloğlu, Recep; Kurtoğlu, Mehmet

2002-04-01

Our aim was to emphasize the role of endoscopic detorsion in the treatment of sigmoid colon volvulus, which we currently apply in the majority of our cases. The data of 37 patients were analyzed in a retrospective manner, during a 86-month period, between May 1994 and July 2001. The patients were classified into three groups. The first group consisted of 9 patients with resection and anastomosis, the second group consisted of 20 patients with Hartmann's procedure, and the third group consisted of 8 patients with endoscopic detorsion. Complications were encountered in 7 patients (19%), and 3 patients (8%) died following treatment. We favor colonic resection following endoscopic treatment. Resection should be preferred, if endoscopic detorsion is not successful or in the presence of a complication.

Maximally Informative Stimuli and Tuning Curves for Sigmoidal Rate-Coding Neurons and Populations

NASA Astrophysics Data System (ADS)

McDonnell, Mark D.; Stocks, Nigel G.

2008-08-01

A general method for deriving maximally informative sigmoidal tuning curves for neural systems with small normalized variability is presented. The optimal tuning curve is a nonlinear function of the cumulative distribution function of the stimulus and depends on the mean-variance relationship of the neural system. The derivation is based on a known relationship between Shannon’s mutual information and Fisher information, and the optimality of Jeffrey’s prior. It relies on the existence of closed-form solutions to the converse problem of optimizing the stimulus distribution for a given tuning curve. It is shown that maximum mutual information corresponds to constant Fisher information only if the stimulus is uniformly distributed. As an example, the case of sub-Poisson binomial firing statistics is analyzed in detail.

Anesthesia management of surgery for sigmoid perforation and acute peritonitis patient following heart transplantation: case report

PubMed Central

Yang, Xu-Li; Dai, Shu-Hong; Zhang, Juan; Zhang, Jing; Liu, Yan-Jun; Yang, Yan; Sun, Yu-E; Ma, Zheng-Liang; Gu, Xiao-Ping

2015-01-01

Here we described a case in which a patient underwent emergency laparotomy for acute peritonitis and sigmoid perforation under general anesthesia with a history of heart transplantation. A good knowledge in the physiology of the transplanted heart is critical for effective and safe general anesthesia. We chose etomidate that have a weaker impact on cardiovascular function plus propofol for induction, and propofol plus cisatracurium for maintenance with intermittently analgesics and vasoactive drugs to facilitate the anesthesia. In addition, fluid input, electrolyte and acid-base balance were well adjusted during the whole procedure. The patient was in good condition after the surgery. In this case report we are aiming to provide some guidance for those scheduled for non-cardiac surgery after heart transplant. PMID:26379997

A ganglioneuroma of the sigmoid colon presenting as leading point of intussusception in a child: a case report.

PubMed

Soccorso, Giampiero; Puls, Florian; Richards, Cathy; Pringle, Howard; Nour, Shawqui

2009-01-01

We present a case of intestinal ganglioneuroma (GN) of the sigmoid colon in a 5-year-old girl, which caused intermittent colocolic intussusception. Ganglioneuromas are rare benign tumors of the autonomic nervous system composed of mature ganglion cells and satellite cells. Colonic GNs are uncommon. The unusual intramural proliferation of neural elements in this case resembled the diffuse intestinal ganglioneuromatosis, which is known to be associated with multiple endocrine neoplasia type 2B. However, the specific mutations of multiple endocrine neoplasia type 2B were not found by genetic sequencing. This is the first pediatric case described in the literature of a solitary polypoid GN presenting as a colocolic intussusception. We present a brief overview of intestinal ganglioneuromatous lesions and associated conditions.

Laparoscopy-assisted sigmoid resection.

PubMed

Fowler, D L; White, S A

1991-09-01

Laparoscopic cholecystectomy has been widely accepted, and because of its many benefits, other intra-abdominal operations are now being done laparoscopically. We felt the next step in the evolution of laparoscopic surgery could be bowel resection. This paper presents two cases of laparoscopic sigmoid resection and a detailed description of the technique. Included in the technique is the use of prototype endoscopic stapling devices to divide the mesentery and bowel. The two most difficult technical decisions involved the methods for specimen removal and for completing the anastomosis. The specimen was removed through a muscle splitting incision in the left lower quadrant, positioned as a mirror image of a standard appendectomy incision. The anvil of the CEEA (end-to-end) stapler was also position in the proximal colon through this incision; the anastomosis was completed with the CEEA stapler.

Closed-edged bilayer phosphorene nanoribbons producing from collapsing armchair phosphorene nanotubes.

PubMed

Liao, Xiangbiao; Xiao, Hang; Lu, Xiaobo; Chen, Youlong; Shi, Xiaoyang; Chen, Xi

2018-02-23

A new phosphorous allotrope, closed-edged bilayer phosphorene nanoribbon, is proposed via radially deforming armchair phosphorene nanotubes. Using molecular dynamics simulations, the transformation pathway from round PNTs falls into two types of collapsed structures: arc-like and sigmoidal bilayer nanoribbons, dependent on the number of phosphorene unit cells. The fabricated nanoribbions are energetically more stable than their parent nanotubes. It is also found via ab initio calculations that the band structure along tube axis substantially changes with the structural transformation. The direct-to-indirect transition of band gap is highlighted when collapsing into the arc-like nanoribbons but not the sigmoidal ones. Furthermore, the band gaps of these two types of nanoribbons show significant size-dependence of the nanoribbon width, indicative of wider tunability of their electrical properties.

[A case of an ulcer of the sigmoid colon during chemotherapy with FOLFOX4 and bevacizumab for recurrence of rectal carcinoma].

PubMed

Okuya, Koichi; Mizushima, Yasuhiro; Hirata, Koichi

2013-01-01

The patient was a 73-year-old female. After curative resection for rectal cancer with uterus invasion, UFT/Leucovorin was administered orally for 16 months. Three years and six months after the initial surgery, en bloc cystourethrectomy was performed to control the bleeding caused by a local recurrence invading the bladder and ureter. Although postoperative FOL- FOX4/bevacizumab therapy was started, bevacizumab was discontinued after 4 courses of treatment because an ulcer was confirmed at the sigmoid colon with stoma. The ulcer was relieved by conservative medical treatment. In this case, we attempted to make a quick response because the site of the ulcer could be easily observed. During chemotherapy. Therefore, it is necessary to carefully observe the patient's conditions.

Surgical Management of Functional Constipation: Preliminary Report of a New Approach Using a Laparoscopic Sigmoid Resection Combined with a Malone Appendicostomy.

PubMed

Gasior, Alessandra; Brisighelli, Giulia; Diefenbach, Karen; Lane, Victoria Alison; Reck, Carlos; Wood, Richard J; Levitt, Marc

2017-08-01

Introduction  Functional constipation is a common problem in children. It usually can be managed with laxatives but a small subset of patients develop intolerable cramps and need to be temporarily treated with enemas. The senior author has previously reported: 1) open sigmoid resection as a surgical option, but this did not sufficiently reduce the laxative need, then 2) a transanal approach (with resection of rectosigmoid), but this led to a high rate of soiling due to extensive stretching of the anal canal and loss of the rectal reservoir. The understanding of these procedures' results has led us to use a laparoscopic sigmoid ± left colonic resection with a Malone appendicostomy for these patients, to decrease the laxative requirements, temporarily treat with antegrade flushes, and to reduce postoperative soiling. Methods  A single-institution retrospective review (3/2014-9/2015) included patients who failed our laxative protocol, and therefore were considered surgical candidates. Patients with anorectal malformation (ARM), Hirschsprung disease, spina bifida, tethered cord, trisomy 21, cerebral palsy, mitochondrial disease, prior colon resection at other facilities, or those that did not participate in our laxative program were excluded. Demographics, duration of symptoms, prior treatments, postoperative complications, and postoperative bowel regimens were evaluated. Results  A total of 6 patients (3 males; median age of 12.5 years) presented with soiling related to constipation and intolerance to laxatives. Four patients failed preoperative cecostomy (done prior to referral to us). An average of 4.7 medication treatments were previously tried. In all, 4 patients had required in-patient disimpactions. Duration of symptoms was 7.5 years (median). The median senna dose was 30 mg (range, 15-150 mg), and all patients had intolerable symptoms or failed to empty their colon, which we considered a failed laxative trial. All had contrast enemas that demonstrated a dilated and/or redundant sigmoid colon, and colonic manometry was abnormal in 4. All patients underwent laparoscopic sigmoid and left colon resection, or only sigmoid resection (a low anterior resection). Two patients had postoperative colitis treated with oral antibiotics. The median follow-up was 52 days (range, 8-304 days). Five patients are on antegrade enemas with plans to convert to laxatives at 6 months, 1 is taking laxatives alone at a 33% lower dosage. Five of six are completely clean, 1 soils occasionally and their daily flush is being adjusted. Conclusion  Only a minority of patients with functional constipation are medically unmanageable. This preliminary report shows that laparoscopic colon resection combined with antegrade flushes is an effective surgical technique to treat that group. A laparoscopic approach, guided by contrast enema and colonic manometry, allows for a defined resection of the abnormal segment of colon with the advantages of minimally invasive surgery including allowing for an extensive rectal resection (an improvement over open sigmoid resection) and avoidance of overstretching of the anal canal and removal of the rectal reservoir (an improvement over the transanal approach). Having antegrade access is useful to manage soiling and avoiding cramping from laxatives in the early postoperative period. Although our series is small, we believe that long-term most patients can avoid antegrade flushes and be on no, or a dramatically reduced, laxative dose. Georg Thieme Verlag KG Stuttgart · New York.

Mathematical model of optical signals emitted by electrical discharges occuring in electroinsulating oil

NASA Astrophysics Data System (ADS)

Kozioł, Michał

2017-10-01

The article presents a parametric model describing the registered distributions spectrum of optical radiation emitted by electrical discharges generated in the systems: the needle- needle, the needleplate and in the system for surface discharges. Generation of electrical discharges and registration of the emitted radiation was carried out in three different electrical insulating oils: fabric new, operated (used) and operated with air bubbles. For registration of optical spectra in the range of ultraviolet, visible and near infrared a high resolution spectrophotometer was. The proposed mathematical model was developed in a regression procedure using gauss-sigmoid type function. The dependent variable was the intensity of the recorded optical signals. In order to estimate the optimal parameters of the model an evolutionary algorithm was used. The optimization procedure was performed in Matlab environment. For determination of the matching quality of theoretical parameters of the regression function to the empirical data determination coefficient R2 was applied.

Applicability of the linear-quadratic formalism for modeling local tumor control probability in high dose per fraction stereotactic body radiotherapy for early stage non-small cell lung cancer.

PubMed

Guckenberger, Matthias; Klement, Rainer Johannes; Allgäuer, Michael; Appold, Steffen; Dieckmann, Karin; Ernst, Iris; Ganswindt, Ute; Holy, Richard; Nestle, Ursula; Nevinny-Stickel, Meinhard; Semrau, Sabine; Sterzing, Florian; Wittig, Andrea; Andratschke, Nicolaus; Flentje, Michael

2013-10-01

To compare the linear-quadratic (LQ) and the LQ-L formalism (linear cell survival curve beyond a threshold dose dT) for modeling local tumor control probability (TCP) in stereotactic body radiotherapy (SBRT) for stage I non-small cell lung cancer (NSCLC). This study is based on 395 patients from 13 German and Austrian centers treated with SBRT for stage I NSCLC. The median number of SBRT fractions was 3 (range 1-8) and median single fraction dose was 12.5 Gy (2.9-33 Gy); dose was prescribed to the median 65% PTV encompassing isodose (60-100%). Assuming an α/β-value of 10 Gy, we modeled TCP as a sigmoid-shaped function of the biologically effective dose (BED). Models were compared using maximum likelihood ratio tests as well as Bayes factors (BFs). There was strong evidence for a dose-response relationship in the total patient cohort (BFs>20), which was lacking in single-fraction SBRT (BFs<3). Using the PTV encompassing dose or maximum (isocentric) dose, our data indicated a LQ-L transition dose (dT) at 11 Gy (68% CI 8-14 Gy) or 22 Gy (14-42 Gy), respectively. However, the fit of the LQ-L models was not significantly better than a fit without the dT parameter (p=0.07, BF=2.1 and p=0.86, BF=0.8, respectively). Generally, isocentric doses resulted in much better dose-response relationships than PTV encompassing doses (BFs>20). Our data suggest accurate modeling of local tumor control in fractionated SBRT for stage I NSCLC with the traditional LQ formalism. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

A New Method to Compare Statistical Tree Growth Curves: The PL-GMANOVA Model and Its Application with Dendrochronological Data

PubMed Central

Ricker, Martin; Peña Ramírez, Víctor M.; von Rosen, Dietrich

2014-01-01

Growth curves are monotonically increasing functions that measure repeatedly the same subjects over time. The classical growth curve model in the statistical literature is the Generalized Multivariate Analysis of Variance (GMANOVA) model. In order to model the tree trunk radius (r) over time (t) of trees on different sites, GMANOVA is combined here with the adapted PL regression model Q = A·T+E, where for and for , A =  initial relative growth to be estimated, , and E is an error term for each tree and time point. Furthermore, Ei[–b·r]  = , , with TPR being the turning point radius in a sigmoid curve, and at is an estimated calibrating time-radius point. Advantages of the approach are that growth rates can be compared among growth curves with different turning point radiuses and different starting points, hidden outliers are easily detectable, the method is statistically robust, and heteroscedasticity of the residuals among time points is allowed. The model was implemented with dendrochronological data of 235 Pinus montezumae trees on ten Mexican volcano sites to calculate comparison intervals for the estimated initial relative growth . One site (at the Popocatépetl volcano) stood out, with being 3.9 times the value of the site with the slowest-growing trees. Calculating variance components for the initial relative growth, 34% of the growth variation was found among sites, 31% among trees, and 35% over time. Without the Popocatépetl site, the numbers changed to 7%, 42%, and 51%. Further explanation of differences in growth would need to focus on factors that vary within sites and over time. PMID:25402427

Grain dynamics and plastic properties of highly refined materials

NASA Astrophysics Data System (ADS)

Lagos, Miguel; Retamal, César

2010-12-01

It has been shown that a grain boundary may undergo two competing classes of elastic instability when the in-plane shear stress exceeds the proper critical values. It may buckle acquiring a sinusoidal shape or may develop a periodic series of fissures, separating bands with a sigmoidal profile. The two instabilities lead to grain sliding, but the corresponding expressions relating the relative velocity between adjacent grains with stress do differ. The plastic properties for small strains were calculated for the two force laws, which we called force models A and B. A comparison of the theoretical results with published experimental data shows that model A, while giving predictions within the experimental uncertainties for a series of superplastic aluminium and titanium alloys, fails for Avesta 2304 steel. However, excellent results are obtained when model B is applied for this steel.

EXTRAPOLATION OF THE SOLAR CORONAL MAGNETIC FIELD FROM SDO/HMI MAGNETOGRAM BY A CESE-MHD-NLFFF CODE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang Chaowei; Feng Xueshang, E-mail: cwjiang@spaceweather.ac.cn, E-mail: fengx@spaceweather.ac.cn

Due to the absence of direct measurement, the magnetic field in the solar corona is usually extrapolated from the photosphere in a numerical way. At the moment, the nonlinear force-free field (NLFFF) model dominates the physical models for field extrapolation in the low corona. Recently, we have developed a new NLFFF model with MHD relaxation to reconstruct the coronal magnetic field. This method is based on CESE-MHD model with the conservation-element/solution-element (CESE) spacetime scheme. In this paper, we report the application of the CESE-MHD-NLFFF code to Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI) data with magnetograms sampled for two activemore » regions (ARs), NOAA AR 11158 and 11283, both of which were very non-potential, producing X-class flares and eruptions. The raw magnetograms are preprocessed to remove the force and then inputted into the extrapolation code. Qualitative comparison of the results with the SDO/AIA images shows that our code can reconstruct magnetic field lines resembling the EUV-observed coronal loops. Most important structures of the ARs are reproduced excellently, like the highly sheared field lines that suspend filaments in AR 11158 and twisted flux rope which corresponds to a sigmoid in AR 11283. Quantitative assessment of the results shows that the force-free constraint is fulfilled very well in the strong-field regions but apparently not that well in the weak-field regions because of data noise and numerical errors in the small currents.« less

A hysteretic model considering Stribeck effect for small-scale magnetorheological damper

NASA Astrophysics Data System (ADS)

Zhao, Yu-Liang; Xu, Zhao-Dong

2018-06-01

Magnetorheological (MR) damper is an ideal semi-active control device for vibration suppression. The mechanical properties of this type of devices show strong nonlinear characteristics, especially the performance of the small-scale dampers. Therefore, developing an ideal model that can accurately describe the nonlinearity of such device is crucial to control design. In this paper, the dynamic characteristics of a small-scale MR damper developed by our research group is tested, and the Stribeck effect is observed in the low velocity region. Then, an improved model based on sigmoid model is proposed to describe this Stribeck effect observed in the experiment. After that, the parameters of this model are identified by genetic algorithms, and the mathematical relationship between these parameters and the input current, excitation frequency and amplitude is regressed. Finally, the predicted forces of the proposed model are validated with the experimental data. The results show that this model can well predict the mechanical properties of the small-scale damper, especially the Stribeck effect in the low velocity region.

Modified ADM1 disintegration/hydrolysis structures for modeling batch thermophilic anaerobic digestion of thermally pretreated waste activated sludge.

PubMed

Ramirez, Ivan; Mottet, Alexis; Carrère, Hélène; Déléris, Stéphane; Vedrenne, Fabien; Steyer, Jean-Philippe

2009-08-01

Anaerobic digestion disintegration and hydrolysis have been traditionally modeled according to first-order kinetics assuming that their rates do not depend on disintegration/hydrolytic biomass concentrations. However, the typical sigmoid-shape increase in time of the disintegration/hydrolysis rates cannot be described with first-order models. For complex substrates, first-order kinetics should thus be modified to account for slowly degradable material. In this study, a slightly modified IWA ADM1 model is presented to simulate thermophilic anaerobic digestion of thermally pretreated waste activated sludge. Contois model is first included for disintegration and hydrolysis steps instead of first-order kinetics and Hill function is then used to model ammonia inhibition of aceticlastic methanogens instead of a non-competitive function. One batch experimental data set of anaerobic degradation of a raw waste activated sludge is used to calibrate the proposed model and three additional data sets from similar sludge thermally pretreated at three different temperatures are used to validate the parameters values.

Population PK-PD analyses of CD25 occupancy, CD56bright NK cell expansion, and regulatory T cell reduction by daclizumab HYP in subjects with multiple sclerosis.

PubMed

Diao, Lei; Hang, Yaming; Othman, Ahmed A; Mehta, Devangi; Amaravadi, Lakshmi; Nestorov, Ivan; Tran, Jonathan Q

2016-11-01

Daclizumab high yield process (HYP) is a humanized IgG1 monoclonal antibody that binds to the α-subunit of the interleukin-2 receptor and is being developed for treatment of multiple sclerosis (MS). This manuscript characterized the pharmacokinetic-pharmacodynamic (PK-PD) relationships of daclizumab HYP in subjects with MS. Approximately 1400 subjects and 7000 PD measurements for each of three biomarkers [CD25 occupancy, CD56 bright natural killer (NK) cell count, regulatory T cell (Treg) count] from four clinical trials were analyzed using non-linear mixed effects modelling. Evaluated regimens included 150 or 300 mg subcutaneous (s.c.) every 4 weeks. CD25 occupancy was characterized using a sigmoidal maximum response (E max ) model. Upon daclizumab HYP treatment, CD25 saturation was rapid with complete saturation occurring after approximately 7 h and maintained when daclizumab HYP serum concentration was ≥5 mg l -1 . After the last 150 mg s.c. dose, unoccupied CD25 returned to baseline levels in approximately 24 weeks, with daclizumab HYP serum concentration approximately ≤1 mgl -1 1L. CD56 bright NK cell expansion was characterized using an indirect response model. Following daclizumab HYP 150 mg s.c. every 4 weeks, expansion plateaus approximately at week 36, at which the average maximum expansion ratio is 5.2. After the last dose, CD56 bright NK cells gradually declined to baseline levels within 24 weeks. Treg reduction was characterized by a sigmoidal E max model. Average maximum reduction of 60% occurred approximately 4 days post 150 mg s.c. dose. After the last dose, Tregs were projected to return to baseline levels in approximately 20 weeks. Robust PK-PD models of CD25 occupancy, CD56 bright NK cell expansion and Treg reduction by daclizumab HYP were developed to characterize its key pharmacodynamic effects in the target patient population. © 2016 The British Pharmacological Society.

Make the most of your samples: Bayes factor estimators for high-dimensional models of sequence evolution.

PubMed

Baele, Guy; Lemey, Philippe; Vansteelandt, Stijn

2013-03-06

Accurate model comparison requires extensive computation times, especially for parameter-rich models of sequence evolution. In the Bayesian framework, model selection is typically performed through the evaluation of a Bayes factor, the ratio of two marginal likelihoods (one for each model). Recently introduced techniques to estimate (log) marginal likelihoods, such as path sampling and stepping-stone sampling, offer increased accuracy over the traditional harmonic mean estimator at an increased computational cost. Most often, each model's marginal likelihood will be estimated individually, which leads the resulting Bayes factor to suffer from errors associated with each of these independent estimation processes. We here assess the original 'model-switch' path sampling approach for direct Bayes factor estimation in phylogenetics, as well as an extension that uses more samples, to construct a direct path between two competing models, thereby eliminating the need to calculate each model's marginal likelihood independently. Further, we provide a competing Bayes factor estimator using an adaptation of the recently introduced stepping-stone sampling algorithm and set out to determine appropriate settings for accurately calculating such Bayes factors, with context-dependent evolutionary models as an example. While we show that modest efforts are required to roughly identify the increase in model fit, only drastically increased computation times ensure the accuracy needed to detect more subtle details of the evolutionary process. We show that our adaptation of stepping-stone sampling for direct Bayes factor calculation outperforms the original path sampling approach as well as an extension that exploits more samples. Our proposed approach for Bayes factor estimation also has preferable statistical properties over the use of individual marginal likelihood estimates for both models under comparison. Assuming a sigmoid function to determine the path between two competing models, we provide evidence that a single well-chosen sigmoid shape value requires less computational efforts in order to approximate the true value of the (log) Bayes factor compared to the original approach. We show that the (log) Bayes factors calculated using path sampling and stepping-stone sampling differ drastically from those estimated using either of the harmonic mean estimators, supporting earlier claims that the latter systematically overestimate the performance of high-dimensional models, which we show can lead to erroneous conclusions. Based on our results, we argue that highly accurate estimation of differences in model fit for high-dimensional models requires much more computational effort than suggested in recent studies on marginal likelihood estimation.

A novel two-step optimization method for tandem and ovoid high-dose-rate brachytherapy treatment for locally advanced cervical cancer.

PubMed

Sharma, Manju; Fields, Emma C; Todor, Dorin A

2015-01-01

To present a novel method allowing fast volumetric optimization of tandem and ovoid high-dose-rate treatments and to quantify its benefits. Twenty-seven CT-based treatment plans from 6 consecutive cervical cancer patients treated with four to five intracavitary tandem and ovoid insertions were used. Initial single-step optimized plans were manually optimized, approved, and delivered plans created with a goal to cover high-risk clinical target volume (HR-CTV) with D90 >90% and minimize rectum, bladder, and sigmoid D2cc. For the two-step optimized (TSO) plan, each single-step optimized plan was replanned adding a structure created from prescription isodose line to the existent physician delineated HR-CTV, rectum, bladder, and sigmoid. New, more rigorous dose-volume histogram constraints for the critical organs at risks (OARs) were used for the optimization. HR-CTV D90 and OAR D2ccs were evaluated in both plans. TSO plans had consistently smaller D2ccs for all three OARs while preserving HR-CTV D90. On plans with "excellent" CTV coverage, average D90 of 96% (91-102%), sigmoid, bladder, and rectum D2cc, respectively, reduced on average by 37% (16-73%), 28% (20-47%), and 27% (15-45%). Similar reductions were obtained on plans with "good" coverage, average D90 of 93% (90-99%). For plans with "inferior" coverage, average D90 of 81%, the coverage increased to 87% with concurrent D2cc reductions of 31%, 18%, and 11% for sigmoid, bladder, and rectum, respectively. The TSO can be added with minimal planning time increase but with the potential of dramatic and systematic reductions in OAR D2ccs and in some cases with concurrent increase in target dose coverage. These single-fraction modifications would be magnified over the course of four to five intracavitary insertions and may have real clinical implications in terms of decreasing both acute and late toxicities. Copyright © 2015 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

A contrast enhancement method for improving the segmentation of breast lesions on ultrasonography.

PubMed

Flores, Wilfrido Gómez; Pereira, Wagner Coelho de Albuquerque

2017-01-01

This paper presents an adaptive contrast enhancement method based on sigmoidal mapping function (SACE) used for improving the computerized segmentation of breast lesions on ultrasound. First, from the original ultrasound image an intensity variation map is obtained, which is used to generate local sigmoidal mapping functions related to distinct contextual regions. Then, a bilinear interpolation scheme is used to transform every original pixel to a new gray level value. Also, four contrast enhancement techniques widely used in breast ultrasound enhancement are implemented: histogram equalization (HEQ), contrast limited adaptive histogram equalization (CLAHE), fuzzy enhancement (FEN), and sigmoid based enhancement (SEN). In addition, these contrast enhancement techniques are considered in a computerized lesion segmentation scheme based on watershed transformation. The performance comparison among techniques is assessed in terms of both the quality of contrast enhancement and the segmentation accuracy. The former is quantified by the measure, where the greater the value, the better the contrast enhancement, whereas the latter is calculated by the Jaccard index, which should tend towards unity to indicate adequate segmentation. The experiments consider a data set with 500 breast ultrasound images. The results show that SACE outperforms its counterparts, where the median values for the measure are: SACE: 139.4, SEN: 68.2, HEQ: 64.1, CLAHE: 62.8, and FEN: 7.9. Considering the segmentation performance results, the SACE method presents the largest accuracy, where the median values for the Jaccard index are: SACE: 0.81, FEN: 0.80, CLAHE: 0.79, HEQ: 77, and SEN: 0.63. The SACE method performs well due to the combination of three elements: (1) the intensity variation map reduces intensity variations that could distort the real response of the mapping function, (2) the sigmoidal mapping function enhances the gray level range where the transition between lesion and background is found, and (3) the adaptive enhancing scheme for coping with local contrasts. Hence, the SACE approach is appropriate for enhancing contrast before computerized lesion segmentation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electromanometry of the rectosigmoid in colonic diverticulosis.

PubMed

Viebig, R G; Pontes, J F; Michelsohn, N H

1994-01-01

In order to better understand the rectosigmoid motor activity in diverticular disease of the colon, we studied 186 patients, grouped according to their intestinal habit, the presence of diverticular disease and previous crisis of sigmoid diverticulitis. The intestinal habit was classified as: normal habit, irritable colon syndrome, diarrhea and constipation. The group of diverticulosis was classified by their intestinal habit and by diverticula localization (localized or generalized). The presence of systemic diseases or drug ingestion that could modify intestinal motility, were considered criteria for exclusion. The manometric study was preceded by food stimulus, with 650 kcal meal, by mechanic intestinal cleansing, with 500 ml of saline solution enema and by one hour resting period. A manometric catheter, was introduced by rectosigmoidoscopy, with open ended orifices situated at the sigmoid and upper rectum, respectively. The catheter was perfused by a capillary infusion system and the bowel pressures were registered for 30 minutes, in a thermal paper physiograph. We analyzed the % of activity, mean amplitude and motility index, by non parametric tests. No significant difference was observed between sexes. Difference or close to it were found for the groups with constipation, with or without diverticulosis, and for the latter in its subdivisions (localized, generalized and sigmoid diverticulitis). The rectal motor activity was similar in all groups. There was no difference for diverticulosis and its subdivision, when we take into account the several kinds of intestinal habits and the diverticula localization. The motility index averages showed low values for the sigmoid diverticulitis fact that suggests some dysfunction of this segment (hypocontractility). The key factor differentiating the groups was the presence of constipation and no influence was noted regarding the localization of diverticula or previous inflammatory process on intraluminal pressures. The fact that no difference was found in the mean amplitude or % of activity among patients with or without diverticulosis, suggests that the high pressures in a colonic segment, may not be responsible for the diverticular disease, and there must be other factors, besides motility, accounting for the development of the different forms of this disease.

Short-duration virtual reality simulation training positively impacts performance during laparoscopic colectomy in animal model: results of a single-blinded randomized trial : VR warm-up for laparoscopic colectomy.

PubMed

Araujo, Sergio E A; Delaney, Conor P; Seid, Victor E; Imperiale, Antonio R; Bertoncini, Alexandre B; Nahas, Sergio C; Cecconello, Ivan

2014-09-01

Several studies have demonstrated skills transfer after virtual reality (VR) simulation training in laparoscopic surgery. However, the impact of VR simulation training on transfer of skills related to laparoscopic colectomy remains not investigated. The present study aimed at determining the impact of VR simulation warm-up on performance during laparoscopic colectomy in the porcine model. Fourteen residents naive to laparoscopic colectomy as surgeons were randomly assigned in block to two groups. Seven trainees completed a 2-h VR simulator training in the laparoscopic sigmoid colectomy module (study group). The remaining seven surgeons (control group) underwent no intervention. On the same day, all participants performed a sigmoid colectomy with anastomosis on a pig. All operations were video recorded. Two board-certified expert colorectal surgeons independently assessed performance during the colectomy on the swine. Examiners were blinded to group assignment. The two examiners used a previously validated clinical instrument specific to laparoscopic colectomy. The primary outcome was the generic and specific skills score values. Surgeons undergoing short-duration training on the VR simulator performed significantly better during laparoscopic colectomy on the pig regarding general and specific technical skills evaluation. The average score of generic skills was 17.2 (16.5-18) for the control group and 20.1 (16.5-22) for the study group (p = 0.002). The specific skills average score for the control group was 20.2 (19-21.5) and 24.2 (21-27.5) for the study group (p = 0.001). There was acceptable concordance (Kendall's W) regarding the video assessment of generic (W = 0.78) and specific skills (W = 0.84) between the two examiners. A single short-duration VR simulator practice positively impacted surgeons' generic and specific skills performance required to accomplish laparoscopic colectomy in the swine model.

Large memory capacity in chaotic artificial neural networks: a view of the anti-integrable limit.

PubMed

Lin, Wei; Chen, Guanrong

2009-08-01

In the literature, it was reported that the chaotic artificial neural network model with sinusoidal activation functions possesses a large memory capacity as well as a remarkable ability of retrieving the stored patterns, better than the conventional chaotic model with only monotonic activation functions such as sigmoidal functions. This paper, from the viewpoint of the anti-integrable limit, elucidates the mechanism inducing the superiority of the model with periodic activation functions that includes sinusoidal functions. Particularly, by virtue of the anti-integrable limit technique, this paper shows that any finite-dimensional neural network model with periodic activation functions and properly selected parameters has much more abundant chaotic dynamics that truly determine the model's memory capacity and pattern-retrieval ability. To some extent, this paper mathematically and numerically demonstrates that an appropriate choice of the activation functions and control scheme can lead to a large memory capacity and better pattern-retrieval ability of the artificial neural network models.

Make the most of your samples: Bayes factor estimators for high-dimensional models of sequence evolution

PubMed Central

2013-01-01

Background Accurate model comparison requires extensive computation times, especially for parameter-rich models of sequence evolution. In the Bayesian framework, model selection is typically performed through the evaluation of a Bayes factor, the ratio of two marginal likelihoods (one for each model). Recently introduced techniques to estimate (log) marginal likelihoods, such as path sampling and stepping-stone sampling, offer increased accuracy over the traditional harmonic mean estimator at an increased computational cost. Most often, each model’s marginal likelihood will be estimated individually, which leads the resulting Bayes factor to suffer from errors associated with each of these independent estimation processes. Results We here assess the original ‘model-switch’ path sampling approach for direct Bayes factor estimation in phylogenetics, as well as an extension that uses more samples, to construct a direct path between two competing models, thereby eliminating the need to calculate each model’s marginal likelihood independently. Further, we provide a competing Bayes factor estimator using an adaptation of the recently introduced stepping-stone sampling algorithm and set out to determine appropriate settings for accurately calculating such Bayes factors, with context-dependent evolutionary models as an example. While we show that modest efforts are required to roughly identify the increase in model fit, only drastically increased computation times ensure the accuracy needed to detect more subtle details of the evolutionary process. Conclusions We show that our adaptation of stepping-stone sampling for direct Bayes factor calculation outperforms the original path sampling approach as well as an extension that exploits more samples. Our proposed approach for Bayes factor estimation also has preferable statistical properties over the use of individual marginal likelihood estimates for both models under comparison. Assuming a sigmoid function to determine the path between two competing models, we provide evidence that a single well-chosen sigmoid shape value requires less computational efforts in order to approximate the true value of the (log) Bayes factor compared to the original approach. We show that the (log) Bayes factors calculated using path sampling and stepping-stone sampling differ drastically from those estimated using either of the harmonic mean estimators, supporting earlier claims that the latter systematically overestimate the performance of high-dimensional models, which we show can lead to erroneous conclusions. Based on our results, we argue that highly accurate estimation of differences in model fit for high-dimensional models requires much more computational effort than suggested in recent studies on marginal likelihood estimation. PMID:23497171

Artificial neural network (ANN) method for modeling of sunset yellow dye adsorption using zinc oxide nanorods loaded on activated carbon: Kinetic and isotherm study.

PubMed

Maghsoudi, M; Ghaedi, M; Zinali, A; Ghaedi, A M; Habibi, M H

2015-01-05

In this research, ZnO nanoparticle loaded on activated carbon (ZnO-NPs-AC) was synthesized simply by a low cost and nontoxic procedure. The characterization and identification have been completed by different techniques such as SEM and XRD analysis. A three layer artificial neural network (ANN) model is applicable for accurate prediction of dye removal percentage from aqueous solution by ZnO-NRs-AC following conduction of 270 experimental data. The network was trained using the obtained experimental data at optimum pH with different ZnO-NRs-AC amount (0.005-0.015 g) and 5-40 mg/L of sunset yellow dye over contact time of 0.5-30 min. The ANN model was applied for prediction of the removal percentage of present systems with Levenberg-Marquardt algorithm (LMA), a linear transfer function (purelin) at output layer and a tangent sigmoid transfer function (tansig) in the hidden layer with 6 neurons. The minimum mean squared error (MSE) of 0.0008 and coefficient of determination (R(2)) of 0.998 were found for prediction and modeling of SY removal. The influence of parameters including adsorbent amount, initial dye concentration, pH and contact time on sunset yellow (SY) removal percentage were investigated and optimal experimental conditions were ascertained. Optimal conditions were set as follows: pH, 2.0; 10 min contact time; an adsorbent dose of 0.015 g. Equilibrium data fitted truly with the Langmuir model with maximum adsorption capacity of 142.85 mg/g for 0.005 g adsorbent. The adsorption of sunset yellow followed the pseudo-second-order rate equation. Copyright © 2014 Elsevier B.V. All rights reserved.

Artificial neural network (ANN) method for modeling of sunset yellow dye adsorption using zinc oxide nanorods loaded on activated carbon: Kinetic and isotherm study

NASA Astrophysics Data System (ADS)

Maghsoudi, M.; Ghaedi, M.; Zinali, A.; Ghaedi, A. M.; Habibi, M. H.

2015-01-01

In this research, ZnO nanoparticle loaded on activated carbon (ZnO-NPs-AC) was synthesized simply by a low cost and nontoxic procedure. The characterization and identification have been completed by different techniques such as SEM and XRD analysis. A three layer artificial neural network (ANN) model is applicable for accurate prediction of dye removal percentage from aqueous solution by ZnO-NRs-AC following conduction of 270 experimental data. The network was trained using the obtained experimental data at optimum pH with different ZnO-NRs-AC amount (0.005-0.015 g) and 5-40 mg/L of sunset yellow dye over contact time of 0.5-30 min. The ANN model was applied for prediction of the removal percentage of present systems with Levenberg-Marquardt algorithm (LMA), a linear transfer function (purelin) at output layer and a tangent sigmoid transfer function (tansig) in the hidden layer with 6 neurons. The minimum mean squared error (MSE) of 0.0008 and coefficient of determination (R2) of 0.998 were found for prediction and modeling of SY removal. The influence of parameters including adsorbent amount, initial dye concentration, pH and contact time on sunset yellow (SY) removal percentage were investigated and optimal experimental conditions were ascertained. Optimal conditions were set as follows: pH, 2.0; 10 min contact time; an adsorbent dose of 0.015 g. Equilibrium data fitted truly with the Langmuir model with maximum adsorption capacity of 142.85 mg/g for 0.005 g adsorbent. The adsorption of sunset yellow followed the pseudo-second-order rate equation.

Oncologic outcomes of single-incision versus conventional laparoscopic anterior resection for sigmoid colon cancer: a propensity-score matching analysis.

PubMed

Kim, Chang Woo; Cho, Min Soo; Baek, Se Jin; Hur, Hyuk; Min, Byung Soh; Kang, Jeonghyun; Baik, Seung Hyuk; Lee, Kang Young; Kim, Nam Kyu

2015-03-01

The aim of this study was to investigate oncologic outcomes, as well as perioperative and pathologic outcomes, of single-incision laparoscopic anterior resection (SILAR) compared with conventional laparoscopic anterior resection (CLAR) for sigmoid colon cancer using propensity-score matching analysis. From July 2009 through April 2012, a total of 407 patients underwent laparoscopic anterior resection for sigmoid colon cancer. Data on short- and long-term outcomes were collected prospectively and reviewed. Propensity-score matching was applied at a ratio of 1:2 comparing the SILAR (n = 60) and CLAR (n = 120) groups. There was no difference in operation time, estimated blood loss, time to soft diet, and length of hospital stay; however, the SILAR group showed less pain on postoperative day 2 (mean 2.6 vs. 3.6; p = 0.000) and shorter length of incision (3.3 vs. 7.7 cm; p = 0.000) compared with the CLAR group. Morbidity, mortality, and pathologic outcomes were similar in both groups. The 3-year overall survival rates were 94.5 versus 97.1% (p = 0.223), and disease-free survival rates were 89.5 versus 87.4% (p = 0.751) in the SILAR and CLAR groups, respectively. The long-term oncologic outcomes, as well as short-term outcomes, of SILAR are comparable with those of CLAR. Although SILAR might have some technical difficulties, it appears to be a safe and feasible option, with better cosmetic results.

Bladder augmentation and artificial sphincter implantation: urodynamic behavior and effects on continence.

PubMed

Rodó, Juan S; Cáceres, Freud A; Lerena, Javier R; Rossy, Enrica

2008-02-01

To quantify changes in bladder capacity, pressure and compliance after isolated bladder augmentation or augmentation associated with implantation of an artificial sphincter, and to compare the various types of augmentation. Preoperative and postoperative urodynamic studies were performed in a group of 38 patients (18 males and 20 females; age range 2-19 years), who underwent a type of bladder augmentation. The bladder improved in capacity in all patients (mean values: initial 137 ml, final 336 ml, individual increase 229 ml; 434%) except two, in which the augmentation was done with ureter. The mean pressure improved (initial 32 cm of H(2)O, final 14, decrease per patient 18 cm of H2O; 49%). The curve of compliance, progressively increasing typical of hyperreflexia and poor compliance, present in 70% of the cases preoperatively, improved in 78% cases postoperatively, although there were several different patterns. Urodynamic behavior was analyzed with regard to the tissue used for augmentation (ileum, ureter or sigmoid colon). In the sigmoid colon group, there were no significant differences in the urodynamic behavior of the bladder neo-reservoir in relation to the configuration used. With bladder augmentation comes an increase in bladder capacity, a reduction in pressure, and an improvement in compliance and continence. The level of change in capacity, pressure and compliance varies with the tissue used and the length and caliber of the insert. When the procedure is carried out using sigmoid colon tissue, there are no noteworthy differences among the various possible configurations.

Influence of a highly purified senna extract on colonic epithelium.

PubMed

van Gorkom, B A; Karrenbeld, A; van Der Sluis, T; Koudstaal, J; de Vries, E G; Kleibeuker, J H

2000-01-01

Chronic use of sennoside laxatives often causes pseudomelanosis coli. A recent study suggested that pseudomelanosis coli is associated with an increased colorectal cancer risk. A single high dose of highly purified senna extract increased proliferation rate and reduced crypt length in the sigmoid colon compared to historical controls. To evaluate in a controlled study the effects of highly purified senna extract on cell proliferation and crypt length in the entire colon and on p53 and bcl-2 expression. Addition of a senna extract to colonic lavage was studied in 184 consecutive outpatients. From 32 randomised patients, 15 with sennosides (Sen), 17 without (NSen), biopsies were taken. Proliferative activity was studied in 4 areas of the colon, using 5-bromo-2'-deoxyuridine labelling and immunohistochemistry (labelling index, LI). Expression of p53 and bcl-2 in the sigmoid colon was determined immunohistochemically. Crypts were shorter in Sen than in NSen in the transverse and sigmoid colon. LI was higher in Sen than in NSen in the entire colon. No difference in p53 expression was seen. Bcl-2 expression was higher in both groups when crypts were shorter and/or proliferation was increased. Sennosides induce acute massive cell loss probably by apoptosis, causing shorter crypts, and increased cell proliferation and inhibition of apoptosis to restore cellularity. These effects may reflect the mechanism for the suggested cancer-promoting effect of chronic sennoside use. Copyright 2000 S. Karger AG, Basel

Percutaneous endoscopic sigmoid colostomy for irrigation in the management of bowel dysfunction of adults with central neurologic disease.

PubMed

Ramwell, A; Rice-Oxley, M; Bond, A; Simson, J N L

2011-10-01

Bowel dysfunction results in a major lifestyle disruption for many patients with severe central neurologic disease. Percutaneous endoscopic sigmoid colostomy for irrigation (PESCI) allows antegrade irrigation of the distal large bowel for the management of both incontinence and constipation. This study prospectively assessed the safety and efficacy of PESCI. A PESCI tube was placed endoscopically in the sigmoid colon of 25 patients to allow antegrade irrigation. Control of constipation and fecal incontinence was improved for 21 (84%) of the 25 patients. These patients were followed up for 6-83 months (mean, 43 months), with long-term success for 19 (90%) of the patients. No PESCI had to be removed for technical reasons or for PESCI complications. Late removal of the PESCI was necessary for 2 of the 21 patients. A modified St. Marks Fecal Incontinence Score to assess bowel function before and after PESCI showed a highly significant improvement (P < 0.0001). There were no procedure-related deaths. Complications included minor sepsis at the initial PESCI tube site in four patients and bumper migration in two patients, but there were no complications related to the button device. This study showed that PESCI is a simple, safe, and effective technique for distal antegrade irrigation in the management bowel dysfunction for selected patients with central neurologic disease. A successful PESCI is very likely to continue functioning satisfactorily for a long time without technical problems or local complications.

Transarterial venous sinus occlusion of dural arteriovenous fistulas using ONYX.

PubMed

Torok, Collin M; Nogueira, Raul G; Yoo, Albert J; Leslie-Mazwi, Thabele M; Hirsch, Joshua A; Stapleton, Christopher J; Patel, Aman B; Rabinov, James D

2016-12-01

The purpose of this article is to present a case series of transarterial venous sinus occlusion for dural arteriovenous fistulas (DAVFs) of the transverse and sigmoid sinuses. From 2006 to 2012, 11 patients with DAVF of the transverse and sigmoid sinuses were treated with transarterial closure of the affected venous sinus using ethylene vinyl alcohol copolymer (ONYX). The consecutive retrospective cohort included six female and five male patients with an age range of 30-79. Patients presented with stroke, intracranial hemorrhage, seizure, headache, focal neurologic deficit or cognitive change. Lesions were categorized as Cognard II a + b (n = 5) or Cognard II b (n = 6). Four of this latter group consisted of isolated sinus segments. Selection criteria for dural sinus occlusion included direct multi-hole fistulas involving a broad surface in length or circumference of the sinus wall. External carotid artery (ECA) branches were directly embolized when considered safe. High-risk arterial supply from ICA, PICA, AICA or ECA cranial nerve branches were closed via retrograde approach during sinus occlusion. DAVF closure was accomplished in all 11 patients with a total of 17 embolization procedures using ONYX. High-risk arterial collaterals were closed via artery-artery or artery-sinus-artery embolization. The vein of Labbe was spared in the four cases with initial antegrade flow. No neurologic complications occurred, and DAVF closures were durable on three-month angiography. Transarterial closure of the transverse and sigmoid sinuses. © The Author(s) 2016.

An Onyx tunnel: reconstructive transvenous balloon-assisted Onyx embolization for dural arteriovenous fistula of the transverse-sigmoid sinus.

PubMed

Kerolus, Mena G; Chung, Joonho; Munich, Stephen A; Matsuda, Yoshikazu; Okada, Hideo; Lopes, Demetrius K

2017-11-17

Transvenous embolization is an effective method for treating dural arteriovenous fistulas (DAVFs) of the transverse-sigmoid sinus (TSS). However, in cases of complicated DAVFs, it is difficult to preserve the patency of the dural sinus. The authors describe the technical details of a new reconstructive technique using transvenous balloon-assisted Onyx embolization as another treatment option in a patient with an extensive and complex DAVF of the left TSS. A microcatheter and compliant balloon catheter were navigated into the left internal jugular vein and placed at the distal end of the DAVF in the transverse sinus. The microcatheter was placed between the vessel wall of the TSS and the balloon. After the balloon was fully inflated, Onyx-18 was injected at the periphery of the balloon in a slow, controlled, progressive, stepwise manner; the balloon and microcatheter were simultaneously withdrawn toward the sigmoid sinus, with Onyx encompassing the entirety of the complex DAVF. The Onyx refluxed into multiple arterial feeders in a distal-to-proximal step-by-step manner, ultimately resulting in an Onyx tunnel. The final angiography study revealed complete obliteration of the DAVF and patency of the TSS. The Onyx tunnel, or reconstructive transvenous balloon-assisted Onyx embolization technique, may be an effective treatment option for large, complex DAVFs of the TSS. This technique may provide another option to facilitate the complete obliteration of the DAVF while preserving the functional sinus.

The alterations of the sigmoid-rectal junction in diverticular disease of the colon revealed by MR-defecography.

PubMed

Romagnoli, Francesco; Colaiacomo, Maria Chiara; De Milito, Ritanna; Modini, Claudio; Gualdi, Gianfranco; Catani, Marco

2014-01-01

The sigmoidorectal junction (SRJ) has been defined as an anatomical sphincter with particular physiological behavior that regulates sigmoid and rectum evacuation. Its function in clinical conditions, such as diverticular disease has been advocated. The aim of our study is to identify the SRJ and to compare the morphometric and dynamic features of the SRJ between patients with diverticular disease and healthy subjects using MR-defecography. Sixteen individuals, eight with uncomplicated diverticular disease and eight healthy subjects, were studied using MR-defecography to identify the SRJ and to compare the morphometric and dynamic features observed. In each subject studied, MR-defecography was able to identify the SRJ. This resulted in the identification of a discrete anatomical entity with a mean length of 31.23 mm, located in front of the first sacral vertebra (S1) and at a mean distance of 15.55 cm from the anal verge, with a mean wall thickness of 4.45 mm, significantly different from the sigmoid and rectal parietal thickness. The SRJ wall was significantly thicker in patients with diverticular disease than the controls (P = 0.005), showing a unique shape and behavior in dynamic sequences. Our findings support the hypothesis that SRJ plays a critical role in patients with symptomatic diverticular disease; further investigation may clarify whether specific SRJ analysis, such as MR-defecography, would predict inflammatory complications of this diffuse and heterogenic disease.

Fluid tagging for CT colonography: effectiveness of a 2-hour iodinated oral preparation after incomplete optical colonoscopy.

PubMed

Chang, Kevin J; Rekhi, Satinder S; Anderson, Stephan W; Soto, Jorge A

2011-01-01

To evaluate the distal extent and attenuation of bowel opacification achieved after administration of a single low volume dose of oral contrast 2 hours before computed tomographic colonography (CTC) after incomplete optical colonoscopy. This retrospective study included 144 patients undergoing CTC after incomplete colonoscopy from April 2006 to July 2008 at 2 separate medical centers. Each patient received 20 to 30 mL of diatrizoate meglumine and diatrizoate sodium solution 2 hours before being scanned. The distalmost extent of opacification was: stomach/small bowel, n = 13; cecum, n = 2; ascending colon, n = 7; transverse colon, n = 19; descending colon, n = 14; sigmoid colon, n = 24; rectum, n = 65. The mean attenuation of each opacified segment was: cecum, 449 Hounsfield units (HU); ascending colon, 474 HU; transverse colon, 468 HU; descending colon, 421 HU; sigmoid colon, 391 HU; and rectum, 382 HU. In 103 (71.5%) patients, oral contrast reached the distal colon (descending colon, sigmoid colon, or rectum). The oral contrast did not reach the colon in only 13 (9.0%) patients. Oral administration of a small volume hyperosmolar oral contrast agent 2 hours before CTC results in satisfactory colonic opacification in the majority of patients. Adding same-day fluid tagging in incomplete colonoscopy patients presenting for completion CTC should result in adequate fluid opacification for most of the colon, especially proximal segments not visualized at the time of incomplete colonoscopy.

Trans-proximal tubular steady-state concentration differences studied by micro-puncture and tissue content of sodium and chloride at varying intraluminal sodium concentrations in vitro in rat kidney cortex slices: evidence for a multisite sodium transport system.

PubMed Central

Györy, A Z; Roby, H

1977-01-01

1. With the aid of micropuncture techniques, proximal tubular transepithelial concentration differences for Na (deltaC Na) and chloride (deltaC Cl) were measured in kidney cortex slices at bathing fluid Na concentrations from 10 to 400 m-mole. kg-1. Tissue content of water, Na and K was also measured in such slices. Under steady-state conditions of zero net flux of NaCl and water, deltaC Na represents the sum of active Na transport, factored by the tubular permeability coefficient added to a component of flux due to electrical forces. 2. The relation between bathing fluid Na concentraton and deltaC Na appeared sigmoid in form suggesting an allosteric mechanism for the transport step. 3. Transtubular potential difference, calculated from transepithelial Cl distribution ratios, did not appear constant at the various bathing fluid Na concentrations. Correcting for the effect of these potential differences on the value of each deltaC Na did not convert the sigmoid transport curve to a hyperbolic one, confirming the suggested allosteric nature of the active Na transport step. 4. Intracellular Na content varied linearly with bathing fluid Na concentrations implying free entry of this cation into the cell. This also suggests that the sigmoid transport curve is related to the properties of the active Na transport pump. PMID:856986

Interactive and scale invariant segmentation of the rectum/sigmoid via user-defined templates

NASA Astrophysics Data System (ADS)

Lüddemann, Tobias; Egger, Jan

2016-03-01

Among all types of cancer, gynecological malignancies belong to the 4th most frequent type of cancer among women. Besides chemotherapy and external beam radiation, brachytherapy is the standard procedure for the treatment of these malignancies. In the progress of treatment planning, localization of the tumor as the target volume and adjacent organs of risks by segmentation is crucial to accomplish an optimal radiation distribution to the tumor while simultaneously preserving healthy tissue. Segmentation is performed manually and represents a time-consuming task in clinical daily routine. This study focuses on the segmentation of the rectum/sigmoid colon as an Organ-At-Risk in gynecological brachytherapy. The proposed segmentation method uses an interactive, graph-based segmentation scheme with a user-defined template. The scheme creates a directed two dimensional graph, followed by the minimal cost closed set computation on the graph, resulting in an outlining of the rectum. The graphs outline is dynamically adapted to the last calculated cut. Evaluation was performed by comparing manual segmentations of the rectum/sigmoid colon to results achieved with the proposed method. The comparison of the algorithmic to manual results yielded to a Dice Similarity Coefficient value of 83.85+/-4.08%, in comparison to 83.97+/-8.08% for the comparison of two manual segmentations of the same physician. Utilizing the proposed methodology resulted in a median time of 128 seconds per dataset, compared to 300 seconds needed for pure manual segmentation.

OBSERVATIONS OF MAGNETIC FLUX-ROPE OSCILLATION DURING THE PRECURSOR PHASE OF A SOLAR ERUPTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, G. P.; Wang, J. X.; Zhang, J., E-mail: gpzhou@nao.cas.cn, E-mail: wangjx@nao.cas.cn, E-mail: jzhang7@gmu.edu

2016-05-20

Based on combined observations from the Interface Region Imaging Spectrograph (IRIS) spectrometer with the coronal emission line of Fe xxi at 1354.08 Å and SDO /AIA images in multiple passbands, we report the finding of the precursor activity manifested as the transverse oscillation of a sigmoid, which is likely a pre-existing magnetic flux rope (MFR), that led to the onset of an X class flare and a fast halo coronal mass ejection (CME) on 2014 September 10. The IRIS slit is situated at a fixed position that is almost vertical to the main axis of the sigmoid structure that hasmore » a length of about 1.8 × 10{sup 5} km. This precursor oscillation lasts for about 13 minutes in the MFR and has velocities in the range of [−9, 11] km s{sup −1} and a period of ∼280 s. Our analysis, which is based on the temperature, density, length, and magnetic field strength of the observed sigmoid, indicates that the nature of the oscillation is a standing wave of fast magnetoacoustic kink mode. We further find that the precursor oscillation is excited by the energy released through an external magnetic reconnection between the unstable MFR and the ambient magnetic field. It is proposed that this precursor activity leads to the dynamic formation of a current sheet underneath the MFR that subsequently reconnects to trigger the onset of the main phase of the flare and the CME.« less

Colonic obstruction secondary to sigmoid fecaloma endoscopically resolved with Coca-Cola®.

PubMed

Ontanilla Clavijo, Guillermo; León Montañés, Rafael; Sánchez Torrijos, Yolanda; López Ruiz, Teófilo; Bozada García, Juan Manuel

2017-04-01

Colonic obstruction is a relatively common condition in emergency care, with a mortality rate of up to 20%. In 90% of cases it results from colonic or rectal adenocarcinoma, volvulus, or stenosis secondary to diverticular disease. When fecal impaction is the underlying cause, the condition is usually managed conservatively, but may on occasion become complicated and even require surgical intervention. Based on the proven efficacy of Coca-Cola® to dissolve gastric phytobezoars, we report a case of colonic obstruction secondary to sigmoid fecaloma. A 58 years old woman arrived at the Emergency Room (ER) with persistent constipation for the last six days. An abdominal CT scan showed a large fecal mass at the sigmoid colon with retrograde dilated colonic loops. Cleansing enemas and oral lactulose were administered, which failed to resolve the clinical presentation, so we then proceeded to inject Coca-Cola® within the fecaloma using a sclerosing needle, and then washed the fecaloma surface also with Coca-Cola®. After a few minutes we started to fragment the fecalith, the consistency of which had been notably decreased. The use of Coca-Cola® for gastric washes in the management of phytobezoars is well established. Since fecaliths are partly composed of these same substances than phytobezoars, the use of Coca-Cola® might well be warranted against them as in our patient, without surgery. Our case report is the second one published in the literature, in which Coca-Cola® helped solve colonic obstruction secondary to fecaloma.

Design and implementation of a film dosimetry audit tool for comparison of planned and delivered dose distributions in high dose rate (HDR) brachytherapy

NASA Astrophysics Data System (ADS)

Palmer, Antony L.; Lee, Chris; Ratcliffe, Ailsa J.; Bradley, David; Nisbet, Andrew

2013-10-01

A novel phantom is presented for ‘full system’ dosimetric audit comparing planned and delivered dose distributions in HDR gynaecological brachytherapy, using clinical treatment applicators. The brachytherapy applicator dosimetry test object consists of a near full-scatter water tank with applicator and film supports constructed of Solid Water, accommodating any typical cervix applicator. Film dosimeters are precisely held in four orthogonal planes bisecting the intrauterine tube, sampling dose distributions in the high risk clinical target volume, points A and B, bladder, rectum and sigmoid. The applicator position is fixed prior to CT scanning and through treatment planning and irradiation. The CT data is acquired with the applicator in a near clinical orientation to include applicator reconstruction in the system test. Gamma analysis is used to compare treatment planning system exported RTDose grid with measured multi-channel film dose maps. Results from two pilot audits are presented, using Ir-192 and Co-60 HDR sources, with a mean gamma passing rate of 98.6% using criteria of 3% local normalization and 3 mm distance to agreement (DTA). The mean DTA between prescribed dose and measured film dose at point A was 1.2 mm. The phantom was funded by IPEM and will be used for a UK national brachytherapy dosimetry audit.

Design and implementation of a film dosimetry audit tool for comparison of planned and delivered dose distributions in high dose rate (HDR) brachytherapy.

PubMed

Palmer, Antony L; Lee, Chris; Ratcliffe, Ailsa J; Bradley, David; Nisbet, Andrew

2013-10-07

A novel phantom is presented for 'full system' dosimetric audit comparing planned and delivered dose distributions in HDR gynaecological brachytherapy, using clinical treatment applicators. The brachytherapy applicator dosimetry test object consists of a near full-scatter water tank with applicator and film supports constructed of Solid Water, accommodating any typical cervix applicator. Film dosimeters are precisely held in four orthogonal planes bisecting the intrauterine tube, sampling dose distributions in the high risk clinical target volume, points A and B, bladder, rectum and sigmoid. The applicator position is fixed prior to CT scanning and through treatment planning and irradiation. The CT data is acquired with the applicator in a near clinical orientation to include applicator reconstruction in the system test. Gamma analysis is used to compare treatment planning system exported RTDose grid with measured multi-channel film dose maps. Results from two pilot audits are presented, using Ir-192 and Co-60 HDR sources, with a mean gamma passing rate of 98.6% using criteria of 3% local normalization and 3 mm distance to agreement (DTA). The mean DTA between prescribed dose and measured film dose at point A was 1.2 mm. The phantom was funded by IPEM and will be used for a UK national brachytherapy dosimetry audit.

[Post mortem temperature equilibration of the structures of the head. I. Thermometric techniques and principal investigations (author's transl)].

PubMed

Brinkmann, B; May, D; Riemann, U

1976-06-30

Special thin and flexible thermometric probes showing a diameter of 1 mm and a sharp end were used for post mortem (p.m.) thermometric studies in several tissues. Brain temperatures were measured by inserting a double probe through the superior orbital fissura thus allowing to record the central and the peripheral brain regions separately. Another probe was inserted into the galea and a fourth into the liver. Temperature changes were recorded simultaneously. Many variables of the human head were measured. Sixteen corpses were investigated. The results were as follows: 1. Of all temperature curves registered those of the central brain regions showed the smallest variance. 2. The p.m. temperature curve of the brain shows a sigmoid shape with a rather short "plateau" in the beginning. 3. In the early p.m. phase there is an increasing difference of temperatures between central and peripheral brain regions amounting to 2-4, 6 degrees C in the time period between 78th and 128th minute. 4. The insertion of the thin probes does not cause visible damages. Thus it should be considered for use in forensic practice. 5. Some artificial "head models" were constructed and temperature decrease recorded after warming. The curves showed the same type of sigmoid shape as those obtained from the corpses. 6. Of the possible variables measured that could influence the temperature decrease only the density of the hair seems to be of interest.

Two-stage DNA compaction induced by silver ions suggests a cooperative binding mechanism

NASA Astrophysics Data System (ADS)

Jiang, Wen-Yan; Ran, Shi-Yong

2018-05-01

The interaction between silver ions and DNA plays an important role in the therapeutic use of silver ions and in related technologies such as DNA sensors. However, the underlying mechanism has not been fully understood. In this study, the dynamics of Ag+-DNA interaction at a single-molecule level was studied using magnetic tweezers. AgNO3 solutions with concentrations ranging from 1 μM to 20 μM led to a 1.4-1.8 μm decrease in length of a single λ-DNA molecule, indicating that Ag+ has a strong binding with DNA, causing the DNA conformational change. The compaction process comprises one linear declining stage and another sigmoid-shaped stage, which can be attributed to the interaction mechanism. Considering the cooperative effect, the sigmoid trend was well explained using a phenomenological model. By contrast, addition of silver nanoparticle solution induced no detectable transition of DNA. The dependence of the interaction on ionic strength and DNA concentration was examined via morphology characterization and particle size distribution measurement. The size of the Ag+-DNA complex decreased with an increase in Ag+ ionic strength ranging from 1 μM to 1 mM. Morphology characterization confirmed that silver ions induced DNA to adopt a compacted globular conformation. At a fixed [AgNO3]:[DNA base pairs] ratio, increasing DNA concentration led to increased sizes of the complexes. Intermolecular interaction is believed to affect the Ag+-DNA complex formation to a large extent.

Crunchiness Loss and Moisture Toughening in Puffed Cereals and Snacks.

PubMed

Peleg, Micha

2015-09-01

Upon moisture uptake, dry cellular cereals and snacks loose their brittleness and become soggy. This familiar phenomenon is manifested in smoothing their compressive force-displacement curves. These curves' degree of jaggedness, expressed by their apparent fractal dimension, can serve as an instrumental measure of the particles' crunchiness. The relationship between the apparent fractal dimension and moisture content or water activity has a characteristic sigmoid shape. The relationship between the sensorily perceived crunchiness and moisture also has a sigmoid shape whose inflection point lies at about the same location. The transition between the brittle and soggy states, however, appears sharper in the apparent fractal dimension compared with moisture plot. Less familiar is the observation that at moderate levels of moisture content, while the particles' crunchiness is being lost, their stiffness actually rises, a phenomenon that can be dubbed "moisture toughening." We show this phenomenon in commercial Peanut Butter Crunch® (sweet starch-based cereal), Cheese Balls (salty starch-based snack), and Pork Rind also known as "Chicharon" (salty deep-fried pork skin), 3 crunchy foods that have very different chemical composition. We also show that in the first 2 foods, moisture toughening was perceived sensorily as increased "hardness." We have concluded that the partial plasticization, which caused the brittleness loss, also inhibited failure propagation, which allowed the solid matrix to sustain higher stresses. This can explain other published reports of the phenomenon in different foods and model systems. © 2015 Institute of Food Technologists®

[Difficulties in diagnosis and surgical treatment of the angiodysplasia of the gastrointestinal tract].

PubMed

Tonea, A; Andrei, S; Andronesi, D; Ionescu, M; Gheorghe, C; Herlea, V; Hortopan, Monica; Andrei, Adriana; Andronesi, Andreea; Popa, C; Popescu, I

2008-01-01

Angiodysplasia (AD) of the gastrointestinal (GI) tract is a rare cause of surgical GI bleeding. It frequently poses difficult problems in diagnosis and treatment. The purpose of this study is to find answers to these problems for a better management of the AD patients. From 1982 to 2006 a total of 75 patients suffering of AD of the GI tract were operated in our center. They represent about 3.6% of total patients operated for GI bleeding in the same period. The age of the patients was between 9 and 81 years old, with two peaks: one between 21 and 40 years old and the other between 51 and 70 years old. The localisation of the lesions was: righ colon +/- ileum 31 patients (41.33%), stomach 13 patients (17.33%), jejunum 6 patients (8%), descendent colon +/- sigmoid 5 patients (6.66%), rectum 4 patients (5.33%), pan-colonic 4 patients (5.33%), sigmoid colon 2 patients (2.66%), cecum + transverse colon 2 patients (2.66%), ileum 2 patients (2.66%), sigmoid colon + jejunum 1 patient (1.33%), cecum + sigmoid colon 1 patient (1.33%), cecum +/- sigmoid colon + jejunum 1 patient (1.33%), jejunum + ileum 1 patient (1.33%), pan-colonic + rectum 1 patient (1.33%). According to Moore classifications 29 patients were type 1 (38%) and 45 patients were type 2 (60%). In one patient AD was associated with Crohn disease (type 4 Fowler). The main symptom in AD was repetitive GI bleeding, of various amplitude, often obscure in origin, the patients having many hospital entries. The medical examination that give us the best help was selective angiography which was positive in 34 of 40 patients (85%). Upper and lower endoscopy were give to 50 surgical patients, being diagnostic in 32 (64%). Histopathologic examinations confirm the diagnosis of AD in all cases, without using injection techniques. All patients were operated for symptomatic AD. Other 11 patients non included in this study were find to have angiodysplastic lesions on operatory specimens for other diseases. The main indications for operative in AD were: continuing digestive hemorrhage of growing amplitude with detected source (54 patients = 72%), inefficient endoscopic and angiographic hemostasis (8 patients = 10.66%) and patients with massive bleeding without any preoperative evaluation (13 patients = 17%). Intraoperative exploration produced little information because of the mucosal and submucosal localisation of the lesions. Operative panendoscopy was the most rewarding investigation. Various types of resections were practiced depending on the site(s) known or presumed of the lesions. Perioperative morbidity was 23% (21 patients), rebleeding being in 4 patients (5.33%). Perioperative mortality was 12% (9 patients) a consequence of advanced age, comorbid conditions and frequent extreme emergency of the operations. Although rare as a cause of surgical digestive bleeding, AD poses often difficult problems of diagnosis and treatment. In patients with GI bleeding, without evident cause, multiple investigated, especially elderly but not always, we must think of an AD.

[Evaluation of a training system for middle ear surgery with optoelectric detection].

PubMed

Strauss, G; Bahrami, N; Pössneck, A; Strauss, M; Dietz, A; Korb, W; Lüth, T; Haase, R; Moeckel, H; Grunert, R

2009-10-01

This work presents a new training concept for surgery of the temporal bone. It is based on a model of gypsum plastic with optoelectric detection of risk structures. A prototypical evaluation is given. The training models are based on high-resolution computed tomographic data of a human skull. The resulting data set was printed by a three-dimensional (3D) printer. A 3D phantom is created from gypsum powder and a bonding agent. Risks structures are the facial nerve, semicircular canal, cochlea, ossicular chain, sigmoid sinus, dura, and internal carotid artery. An electrically conductive metal (Wood's metal) and a fiber-optic cable were used as detection materials for the risk structures. For evaluating the training system, a study was done with eight inexperienced and eight experienced ear surgeons. They were asked to perform temporal bone surgery using two identical training models (group A). In group B, the same surgeons underwent surgical training with human cadavers. In the case of injuries, the number, point in time, degree (facial nerve), and injured structure were documented during the training on the model. In addition, the total time needed was noted. The training systems could be used in all cases. Evaluation of the anatomic accuracy of the models showed results that were between 49.5% and 90% agreement with the anatomic origin. Error detection was evaluated with values between 79% and 100% agreement with the perception of an experienced surgeon. The operating setting was estimated to be better than the previous"gold standard." The possibility of completely replacing the previous training method, which uses cadavers, with the examined training model was affirmed. This study shows that the examined system fulfills the conditions for a new training concept for temporal bone surgery. The system connects the preliminary work with printed and sintered models with the possibilities of microsystem engineering. In addition, the model's digital database permits a complete virtual representation of the model with appropriate further applications ("look behind the wall," virtual endoscopy).

Double-lumen balloon for Onyx® embolization via extracranial arteries in transverse sigmoid dural arteriovenous fistulas: initial experience.

PubMed

Clarençon, Frédéric; Di Maria, Federico; Gabrieli, Joseph; Carpentier, Alexandre; Pistochi, Silvia; Bartolini, Bruno; Zeghal, Chiheb; Chiras, Jacques; Sourour, Nader-Antoine

2016-10-01

Transverse-sigmoid dural arteriovenous fistulas (TS DAVFs) can be challenging to treat by endovascular means. Indeed, a total cure of the fistula can only be achieved when complete occlusion of the fistulous point(s) is obtained by penetration of the embolic agent. However, in some cases, especially for transosseous branches from extracranial arteries like the occipital artery (OcA) or the superficial temporal artery (STA), such penetration is usually poor, leading to major proximal reflux and incomplete fistula obliteration. We present three cases of embolization in two patients with TS DAVF through the OcA and/or the STA with Onyx® using a double-lumen balloon (Microvention, Tustin, CA, USA). This technique allows the penetration of the embolic agent in the transosseous branches by forming a counter-pressure with the inflated balloon. This technique may be useful to achieve complete occlusion of TS DAVFs by endovascular means.

Fault Tolerant Characteristics of Artificial Neural Network Electronic Hardware

NASA Technical Reports Server (NTRS)

Zee, Frank

1995-01-01

The fault tolerant characteristics of analog-VLSI artificial neural network (with 32 neurons and 532 synapses) chips are studied by exposing them to high energy electrons, high energy protons, and gamma ionizing radiations under biased and unbiased conditions. The biased chips became nonfunctional after receiving a cumulative dose of less than 20 krads, while the unbiased chips only started to show degradation with a cumulative dose of over 100 krads. As the total radiation dose increased, all the components demonstrated graceful degradation. The analog sigmoidal function of the neuron became steeper (increase in gain), current leakage from the synapses progressively shifted the sigmoidal curve, and the digital memory of the synapses and the memory addressing circuits began to gradually fail. From these radiation experiments, we can learn how to modify certain designs of the neural network electronic hardware without using radiation-hardening techniques to increase its reliability and fault tolerance.

Sigmoid sinus occlusion infiltrated by inflammatory myofibroblastic tumor from mastoid.

PubMed

Wang, Jingye; Sun, Zhongwu; Zhuo, Shengxia; Wang, Kai

2015-01-01

Inflammatory myofibroblastic tumor (IMT) and some types of immunoglobulin (Ig) G4-related disease are often involved in the spectrum of inflammatory pseudotumor (IPT) and the concept of IgG4-related IPT/IMT has recently been proposed. A 38-year-old man complained of initial symptoms of blurred vision and headache. A tumor was found in the right mastoid, which caused occlusion of the right sigmoid sinus and intracranial hypertension. A diagnosis of IMT with IgG4+ plasma cell infiltration was established by surgical, pathological, and immunohistochemistry findings. His symptoms were completely relieved after corticosteroid therapy and no recurrence was detected during 22 months of follow-up. A case with cerebral venous sinus infiltrated by IMTs in the head and neck has never been reported; corticosteroid therapy proved satisfactory in IMT with IgG4+ plasma cell infiltration. © 2014 Wiley Periodicals, Inc.

An unusual cause of vaginal discharge following gender reassignment.

PubMed

Sukumaran, S; Moran, P A; Makar, A

2009-02-01

Neovaginal reconstruction is an important part of gender reassignment surgery. We report a case of stone formation at the apex of vaginal vault constructed with sigmoid colon segment. A 48-year-old woman presented with profuse vaginal discharge for 1 year. She had a history of gender reassignment surgery (male to female) in 1994, and the neovagina had been constructed with an isolated sigmoid colon. Vaginoscopy performed using a cystoscope revealed multiple calculi at the vaginal vault on the endoscopic gastrointestinal anastomosis staples that had been used to close the vault. Colon-vaginoplasty has the advantages of providing adequate lubrication, but excessive vaginal discharge could be a problem, as colon is a mucous membrane. Stone formation in the vaginal vault should be considered in cases of gender reassignment with persistent vaginal discharge. This case also highlights the use of cystoscope in visualising the upper vagina in difficult circumstances.

Large bowel and small bowel obstruction due to gallstones in the same patient

PubMed Central

Ranga, Natasha

2011-01-01

This is the case report of an 85-year-old woman who on two consecutive occasions presented with acute abdominal pain. The first presentation was large bowel obstruction. CT abdomen revealed this was due to a cholecystocolic fistula, allowing a large gallstone to pass and obstruct in the sigmoid colon. The second presentation was after laparotomy; the second CT abdomen revealed another gallstone causing small bowel obstruction. This case is interesting because cholelithiasis rarely leads to sigmoid colon obstruction (gallstone coleus)1 and gallstone ileus. Unfortunately, this patient had both. A gallstone causing obstruction in either the small or large bowel is rare, but occurrence of both in the same patient has not been reported to date. This case also shows how the elderly unwell surgical patient was mismanaged and she could have been spared surgery and irradiation if she was managed appropriately from the start. PMID:22696674

[Long-Term Survival of a Patient with Sigmoid Colon Cancer with Multiple Visceral Metastases].

PubMed

Sasaki, Yoshiyuki; Nishigori, Naoto; Koyama, Fumikazu; Ueda, Takeshi; Inoue, Takashi; Kawasaki, Keijirou; Obara, Shinsaku; Nakamoto, Takayuki; Nakamura, Yasuyuki; Fujii, Hisao; Nakajima, Yoshiyuki

2016-11-01

A 66-year-old woman underwent total pelvic exenteration for a pelvic tumor. The pathological diagnosis was sigmoid colon cancer T4b(in the small intestine, uterus, and vagina), N0, M0, Stage II . The patient was treated with XELOX for 6 months as adjuvant chemotherapy and was then treated with IRIS for another 6 months. Brain metastasis developed in the left occipital lobe after 12 months, and she underwent craniotomy and enucleation of the tumor. Liver metastasis and peritoneal dissemination metastasis developed 16 months after her initial diagnosis. The patient underwent re-craniotomy and radiotherapy for recurrence of the brain metastasis 18 months after diagnosis and started taking TAS-102 3 months later. She began treatment with CPT-11 plus panitumumab 24 months after diagnosis, and the dose was increased 9 months later(ie, 35 months after the initial diagnosis). The patient remains alive 42 months after surgery.

A New Approach for Validating Satellite Estimates of Soil Moisture Using Large-Scale Precipitation: Comparing AMSR-E Products

NASA Astrophysics Data System (ADS)

Tuttle, S. E.; Salvucci, G.

2012-12-01

Soil moisture influences many hydrological processes in the water and energy cycles, such as runoff generation, groundwater recharge, and evapotranspiration, and thus is important for climate modeling, water resources management, agriculture, and civil engineering. Large-scale estimates of soil moisture are produced almost exclusively from remote sensing, while validation of remotely sensed soil moisture has relied heavily on ground truthing, which is at an inherently smaller scale. Here we present a complementary method to determine the information content in different soil moisture products using only large-scale precipitation data (i.e. without modeling). This study builds on the work of Salvucci [2001], Saleem and Salvucci [2002], and Sun et al. [2011], in which precipitation was conditionally averaged according to soil moisture level, resulting in moisture-outflow curves that estimate the dependence of drainage, runoff, and evapotranspiration on soil moisture (i.e. sigmoidal relations that reflect stressed evapotranspiration for dry soils, roughly constant flux equal to potential evaporation minus capillary rise for moderately dry soils, and rapid drainage for very wet soils). We postulate that high quality satellite estimates of soil moisture, using large-scale precipitation data, will yield similar sigmoidal moisture-outflow curves to those that have been observed at field sites, while poor quality estimates will yield flatter, less informative curves that explain less of the precipitation variability. Following this logic, gridded ¼ degree NLDAS precipitation data were compared to three AMSR-E derived soil moisture products (VUA-NASA, or LPRM [Owe et al., 2001], NSIDC [Njoku et al., 2003], and NSIDC-LSP [Jones & Kimball, 2011]) for a period of nine years (2001-2010) across the contiguous United States. Gaps in the daily soil moisture data were filled using a multiple regression model reliant on past and future soil moisture and precipitation, and soil moisture was then converted to a ranked wetness index, in order to reconcile the wide range and magnitude of the soil moisture products. Generalized linear models were employed to fit a polynomial model to precipitation, given wetness index. Various measures of fit (e.g. log likelihood) were used to judge the amount of information in each soil moisture product, as indicated by the amount of precipitation variability explained by the fitted model. Using these methods, regional patterns appear in soil moisture product performance.

Privacy-preserving outlier detection through random nonlinear data distortion.

PubMed

Bhaduri, Kanishka; Stefanski, Mark D; Srivastava, Ashok N

2011-02-01

Consider a scenario in which the data owner has some private or sensitive data and wants a data miner to access them for studying important patterns without revealing the sensitive information. Privacy-preserving data mining aims to solve this problem by randomly transforming the data prior to their release to the data miners. Previous works only considered the case of linear data perturbations--additive, multiplicative, or a combination of both--for studying the usefulness of the perturbed output. In this paper, we discuss nonlinear data distortion using potentially nonlinear random data transformation and show how it can be useful for privacy-preserving anomaly detection from sensitive data sets. We develop bounds on the expected accuracy of the nonlinear distortion and also quantify privacy by using standard definitions. The highlight of this approach is to allow a user to control the amount of privacy by varying the degree of nonlinearity. We show how our general transformation can be used for anomaly detection in practice for two specific problem instances: a linear model and a popular nonlinear model using the sigmoid function. We also analyze the proposed nonlinear transformation in full generality and then show that, for specific cases, it is distance preserving. A main contribution of this paper is the discussion between the invertibility of a transformation and privacy preservation and the application of these techniques to outlier detection. The experiments conducted on real-life data sets demonstrate the effectiveness of the approach.

Laparoscopic treatment of colovesical fistulas due to complicated colonic diverticular disease: a systematic review.

PubMed

Cirocchi, R; Cochetti, G; Randolph, J; Listorti, C; Castellani, E; Renzi, C; Mearini, E; Fingerhut, A

2014-10-01

Colovesical fistulas originating from complicated sigmoid diverticular disease are rare. The primary aim of this review was to evaluate the role of laparoscopic surgery in the treatment of this complication. The secondary aim was to determine the best surgical treatment for this disease. A systematic search was conducted for studies published between 1992 and 2012 in PubMed, the Cochrane Register of Controlled Clinical Trials, Scopus, and Publish or Perish. Studies enrolling adults undergoing fully laparoscopic, laparoscopic-assisted, or hand-assisted laparoscopic surgery for colovesical fistula secondary to complicated sigmoid diverticular disease were considered. Data extracted concerned the surgical technique, intraoperative outcomes, and postoperative outcomes based on the Cochrane Consumers and Communication Review Group's template. Descriptive statistics were reported according to the PRISMA statement. In all, 202 patients from 25 studies were included in this review. The standard treatment was laparoscopic colonic resection and primary anastomosis or temporary colostomy with or without resection of the bladder wall. Operative time ranged from 150 to 321 min. It was not possible to evaluate the conversion rate to open surgery because colovesical fistulas were not distinguished from other types of enteric fistulas in most of the studies. One anastomotic leak after bowel anastomosis was reported. There was zero mortality. Few studies conducted follow-up longer than 12 months. One patient required two reoperations. Laparoscopic treatment of colovesical fistulas secondary to sigmoid diverticular disease appears to be a feasible and safe approach. However, further studies are needed to establish whether laparoscopy is preferable to other surgical approaches.

Penetrated sigmoid colon by air gun pellet could be life threatening: A case report

PubMed Central

Krasniqi, Avdyl S.; Hamza, Astrit R.; Zejnullahu, Valon A.; Sada, Fatos E.; Bicaj, Besnik X.

2014-01-01

INTRODUCTION Air and paintball guns have been in existence for over 400 year. Although serious injury or death can result from the use of such guns, previous literature has not mentioned the issue of the penetration of the sigmoid colon by an air gun pellet. PRESENTATION OF CASE We report a rare case of a 44-year-old Caucasian woman referred to abdominal surgery after an accidental small wound had occurred in the lower left abdominal quadrant that was caused by an air gun pellet. The blood and biochemical analyses were normal but the CT scan revealed the presence of a foreign body – an air gun pellet in the left iliac region of the abdomen. Clinically, during the initial 24 h significant changes were not noticed. After 42 h, however, pain and local tenderness in the lower left abdominal quadrant was expressed. A laparotomy revealed a retained pellet in the wall of the sigmoid colon and a small leak with colonic content with consecutive local peritonitis also occurred. The foreign body was removed and the opening edges in the colon were excised and closed with the primary suture. DISCUSSION The hollow organs of the digestive tract, albeit very rarely penetrated by an air gun pellet, do not typically show all signs of an acute abdomen in the early posttraumatic phase. Such injuries can lead to a pronounced infection, which may cause septic shock if not appropriately treated. CONCLUSION For correct diagnosis, a careful approach and several daily clinical observations are required. PMID:25437671

Initial experience of single-port laparoscopic surgery for sigmoid colon cancer.

PubMed

Park, Sun Jin; Lee, Kil Yeon; Kang, Byung Mo; Choi, Sung Il; Lee, Suk Hwan

2013-03-01

Single-port laparoscopic surgery has attracted attention in the field of minimally invasive colorectal surgery. We hypothesized that an experienced laparoscopic surgeon could perform single-port surgery for colon cancer eligible for conventional laparoscopic anterior resection. Our aim was to analyze our initial experience and immediate surgical outcomes of single-port anterior resection. A total of 37 consecutive patients with presumed sigmoid colonic cancer underwent single-port anterior resection with standard laparoscopic instruments between May 2009 and June 2010. Each operation was performed by one of two experienced colorectal surgeons. A cohort of patients who had undergone conventional laparoscopic surgery (CLS) for the same duration a year earlier (August 2007 to September 2008) was used as a historical control. Patient demographics and perioperative outcomes were analyzed and compared with those of CLS. There were no significant differences in mean estimated blood loss, mean length of the resection margin, or morbidity between the two groups, but operative time for the single-port group was significantly shorter (118 ± 41 vs. 140 ± 42 min; p = 0.017). Single-port laparoscopic surgery was successfully performed in 78.4% (29/37) of the patients treated in 2010, and CLS was successfully completed in all of the patients treated the previous year (p = 0.000). The main causes of single-port surgery failure were adhesion and tumor location. Single-port anterior resection is a feasible and safe procedure with immediate outcomes comparable to those of conventional laparoscopy. Further studies are required to determine the feasibility of single-port surgery for colonic tumors outside the sigmoid colon and the long-term outcome.

The effects of amiloride and age on oxygen consumption coupled to electrogenic sodium transport in the human sigmoid colon.

PubMed

Carra, Graciela E; Matus, Daniel; Ibáñez, Jorge E; Saraví, Fernando D

2015-01-01

Aerobic metabolism is necessary for ion transport in many transporting epithelia, including the human colonic epithelium. We assessed the effects of the epithelial sodium channel blocker, amiloride, on oxygen consumption and short-circuit current of the human sigmoid epithelium to determine whether these effects were influenced by the age of the subject. Segments of the sigmoid colon were obtained from the safety margin of resections performed in patients of 62-77 years of age. Isolated mucosa preparations were obtained and mounted in airtight Ussing chambers, fit for simultaneous measurement of short-circuit current and oxygen concentration, before and after blocking epithelial sodium channels with amiloride (0.1 mmol/L). Regression analyses were performed to assess the associations between short-circuit current, oxygen consumption, and age of the subject as well as to define the relationship between the decreases in short-circuit current and oxygen consumption after blockade. Epithelial sodium channel blockade caused an 80% reduction in short-circuit current and a 26% reduction in oxygen consumption. Regression analysis indicated that both changes were significantly related (r = 0.884;P = 0.0007). Oxygen consumption decreased by 1 m mol/h/cm2 for each 25 m A/cm2 decrease in short-circuit current. Neither short-circuit current nor oxygen consumption had any significant relationship with the age of the subjects. The decrease in epithelial oxygen consumption caused by amiloride is proportional to the decrease in short-circuit current and independent of the age of the subject.

Evolution of specialization under non-equilibrium population dynamics.

PubMed

Nurmi, Tuomas; Parvinen, Kalle

2013-03-21

We analyze the evolution of specialization in resource utilization in a mechanistically underpinned discrete-time model using the adaptive dynamics approach. We assume two nutritionally equivalent resources that in the absence of consumers grow sigmoidally towards a resource-specific carrying capacity. The consumers use resources according to the law of mass-action with rates involving trade-off. The resulting discrete-time model for the consumer population has over-compensatory dynamics. We illuminate the way non-equilibrium population dynamics affect the evolutionary dynamics of the resource consumption rates, and show that evolution to the trimorphic coexistence of a generalist and two specialists is possible due to asynchronous non-equilibrium population dynamics of the specialists. In addition, various forms of cyclic evolutionary dynamics are possible. Furthermore, evolutionary suicide may occur even without Allee effects and demographic stochasticity. Copyright © 2013 Elsevier Ltd. All rights reserved.

Gossip in Random Networks

NASA Astrophysics Data System (ADS)

Malarz, K.; Szvetelszky, Z.; Szekf, B.; Kulakowski, K.

2006-11-01

We consider the average probability X of being informed on a gossip in a given social network. The network is modeled within the random graph theory of Erd{õ}s and Rényi. In this theory, a network is characterized by two parameters: the size N and the link probability p. Our experimental data suggest three levels of social inclusion of friendship. The critical value pc, for which half of agents are informed, scales with the system size as N-gamma with gamma approx 0.68. Computer simulations show that the probability X varies with p as a sigmoidal curve. Influence of the correlations between neighbors is also evaluated: with increasing clustering coefficient C, X decreases.

Kinetic characterisation of primer mismatches in allele-specific PCR: a quantitative assessment.

PubMed

Waterfall, Christy M; Eisenthal, Robert; Cobb, Benjamin D

2002-12-20

A novel method of estimating the kinetic parameters of Taq DNA polymerase during rapid cycle PCR is presented. A model was constructed using a simplified sigmoid function to represent substrate accumulation during PCR in combination with the general equation describing high substrate inhibition for Michaelis-Menten enzymes. The PCR progress curve was viewed as a series of independent reactions where initial rates were accurately measured for each cycle. Kinetic parameters were obtained for allele-specific PCR (AS-PCR) amplification to examine the effect of mismatches on amplification. A high degree of correlation was obtained providing evidence of substrate inhibition as a major cause of the plateau phase that occurs in the later cycles of PCR.

Pharmacokinetic/pharmacodynamic modeling of cardiac toxicity in human acute overdoses: utility and limitations.

PubMed

Mégarbane, Bruno; Aslani, Arsia Amir; Deye, Nicolas; Baud, Frédéric J

2008-05-01

Hypotension, cardiac failure, QT interval prolongation, dysrhythmias, and conduction disturbances are common complications of overdoses with cardiotoxicants. Pharmacokinetic/pharmacodynamic (PK/PD) relationships are useful to assess diagnosis, prognosis, and treatment efficacy in acute poisonings. To review the utility and limits of PK/PD studies of cardiac toxicity. Discussion of various models, mainly those obtained in digitalis, cyanide, venlafaxine and citalopram poisonings. A sigmoidal E(max) model appears adequate to represent the PK/PD relationships in cardiotoxic poisonings. PK/PD correlations investigate the discrepancies between the time course of the effect magnitude and its evolving concentrations. They may help in understanding the mechanisms of occurrence as well as disappearance of a cardiotoxic effect. When data are sparse, population-based PK/PD modeling using computer-intensive algorithms is helpful to estimate population mean values of PK parameters as well as their individual variability. Further PK/PD studies are needed in medical toxicology to allow understanding of the meaning of blood toxicant concentration in acute poisonings and thus improve management.

Adjudicating between face-coding models with individual-face fMRI responses

PubMed Central

Kriegeskorte, Nikolaus

2017-01-01

The perceptual representation of individual faces is often explained with reference to a norm-based face space. In such spaces, individuals are encoded as vectors where identity is primarily conveyed by direction and distinctiveness by eccentricity. Here we measured human fMRI responses and psychophysical similarity judgments of individual face exemplars, which were generated as realistic 3D animations using a computer-graphics model. We developed and evaluated multiple neurobiologically plausible computational models, each of which predicts a representational distance matrix and a regional-mean activation profile for 24 face stimuli. In the fusiform face area, a face-space coding model with sigmoidal ramp tuning provided a better account of the data than one based on exemplar tuning. However, an image-processing model with weighted banks of Gabor filters performed similarly. Accounting for the data required the inclusion of a measurement-level population averaging mechanism that approximates how fMRI voxels locally average distinct neuronal tunings. Our study demonstrates the importance of comparing multiple models and of modeling the measurement process in computational neuroimaging. PMID:28746335

Mortality profiles of Rhodnius prolixus (Heteroptera: Reduviidae), vector of Chagas disease.

PubMed

Chaves, Luis Fernando; Hernandez, Maria-Josefina; Revilla, Tomás A; Rodríguez, Diego J; Rabinovich, Jorge E

2004-10-01

Life table data of Rhodnius prolixus (Heteroptera: Reduviidae) kept at laboratory conditions were analysed in search for mortality patterns. Gompertz and Weibull mortality models seem adequate to explain the sigmoid shape of the survivorship curve. A significant fit was obtained with both models for females (R(2) = 0.70, P < 0.0005 for the Gompertz model; R(2) = 0.78, P < 0.0005 for the Weibull model) and for males (R(2) = 0.39, P < 0.0005 for the Gompertz model; R(2) = 0.48, P < 0.0005 for the Weibull model). The mortality parameter (b) is higher for females in Gompertz and Weibull models, using smoothed and non-smoothed data (P < 0.05), revealing a significant sex mortality differential. Given the particular life history of this insect, the non-linear relationship between the force of mortality and age may have an important impact in the vectorial capacity of R. prolixus as Chagas disease vector, and its consideration should be included as an important factor in the transmission of Trypanosoma cruzi by triatomines.

THE CHARACTERISTICS OF THE FOOTPOINTS OF SOLAR MAGNETIC FLUX ROPES DURING ERUPTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, X.; Ding, M. D., E-mail: xincheng@nju.edu.cn

2016-07-01

We investigate the footpoints of four erupted magnetic flux ropes (MFRs) that appear as sigmoidal hot channels prior to the eruptions in the Atmospheric Imaging Assembly high temperature passbands. The simultaneous Helioseismic and Magnetic Imager observations disclose that one footpoint of the MFRs originates in the penumbra or penumbra edge with a stronger magnetic field, while the other originates in the moss region with a weaker magnetic field. The significant deviation of the axes of the MFRs from the main polarity inversion lines and associated filaments suggests that the MFRs have ascended to a high altitude, thus becoming distinguishable frommore » the source sigmoidal active regions. Further, with the eruption of the MFRs, the average inclination angle and direct current at the footpoints with stronger magnetic fields tend to decrease, which is suggestive of a straightening and untwisting of the magnetic field in the MFR legs. Moreover, the associated flare ribbons also display an interesting evolution. They initially appear as sporadic brightenings at the two footpoints of the MFRs and in the regions below, and then quickly extend to two slender sheared J-shaped ribbons with the two hooks corresponding to the two ends of the MFRs. Finally, the straight parts of the two ribbons separate from each other, evolving into two widened parallel ones. These features mostly conform to and support the recently proposed three-dimensional standard coronal mass ejection/flare model, i.e., the twisted MFR eruption stretches and leads to the reconnection of the overlying field that transits from a strong to weak shear with increasing height.« less

Reinvasion Dynamics of Subterranean Termites (Isoptera: Rhinotermitidae) Following the Elimination of All Detectable Colonies in a Large Area.

PubMed

Su, Nan-Yao; Guidry, Eric; Mullins, Aaron J; Cotonne, Carrie

2016-04-01

Following the elimination of all detectable termite colonies in the 32-acre Louis Armstrong Park in New Orleans, LA, in 2002–2003, termite activity was monitored by using 808 Sentricon stations. Between January 2004 and July 2005, termites were found in 8–11 stations. In August 2005, the Park was flooded by Hurricane Katrina, but termites remained active. Post-Katrina termite activity levels of 16–21 stations were recorded throughout 2006, and in October 2007, the activity drastically increased to 43 stations. This rapid increase of termite activity continued into 2008, and a total of 94 stations harbored termite activities by July 2008. Termite activity peaked at 109 stations in September 2008 and then leveled down to 64 stations in March 2009. Termite activity in the Park between 2004 and 2009 was described by a Sigmoid model with a carrying capacity of 76 stations, and a Sigmoid mid-point of 1,202 d. In April 2009, a total of 14 colonies of Coptotermes formosanus Shiraki and one colony of Reticulitermes flavipes (Kollar) were delineated by using microsatellite genotyping and mark–recapture protocol. Of the 15 colonies, eight near the Park border probably originated from existing colonies from outside, and seven C. formosanus colonies found inside the Park were probably initiated by alate pairs. Our results showed that, if surrounded by high population pressure of termites and no control measures are applied, an area cleared of termite populations by baits can be completely re-populated by termites from outside in 53 mo.

The Characteristics of the Footpoints of Solar Magnetic Flux Ropes during Eruptions

NASA Astrophysics Data System (ADS)

Cheng, X.; Ding, M. D.

2016-07-01

We investigate the footpoints of four erupted magnetic flux ropes (MFRs) that appear as sigmoidal hot channels prior to the eruptions in the Atmospheric Imaging Assembly high temperature passbands. The simultaneous Helioseismic and Magnetic Imager observations disclose that one footpoint of the MFRs originates in the penumbra or penumbra edge with a stronger magnetic field, while the other originates in the moss region with a weaker magnetic field. The significant deviation of the axes of the MFRs from the main polarity inversion lines and associated filaments suggests that the MFRs have ascended to a high altitude, thus becoming distinguishable from the source sigmoidal active regions. Further, with the eruption of the MFRs, the average inclination angle and direct current at the footpoints with stronger magnetic fields tend to decrease, which is suggestive of a straightening and untwisting of the magnetic field in the MFR legs. Moreover, the associated flare ribbons also display an interesting evolution. They initially appear as sporadic brightenings at the two footpoints of the MFRs and in the regions below, and then quickly extend to two slender sheared J-shaped ribbons with the two hooks corresponding to the two ends of the MFRs. Finally, the straight parts of the two ribbons separate from each other, evolving into two widened parallel ones. These features mostly conform to and support the recently proposed three-dimensional standard coronal mass ejection/flare model, I.e., the twisted MFR eruption stretches and leads to the reconnection of the overlying field that transits from a strong to weak shear with increasing height.

Toxicity Relationship Analysis Program (TRAP) Version 1.21

EPA Science Inventory

The Toxicity Relationship Analysis Program (TRAP) fits a sigmoidal toxic response versus exposure variable relationship to standard toxicity test data. It will analyze binary (e.g., survival) or continuous (e.g., growth, reproduction) biological effect variables as a function o...

Growth curves for ostriches (Struthio camelus) in a Brazilian population.

PubMed

Ramos, S B; Caetano, S L; Savegnago, R P; Nunes, B N; Ramos, A A; Munari, D P

2013-01-01

The objective of this study was to fit growth curves using nonlinear and linear functions to describe the growth of ostriches in a Brazilian population. The data set consisted of 112 animals with BW measurements from hatching to 383 d of age. Two nonlinear growth functions (Gompertz and logistic) and a third-order polynomial function were applied. The parameters for the models were estimated using the least-squares method and Gauss-Newton algorithm. The goodness-of-fit of the models was assessed using R(2) and the Akaike information criterion. The R(2) calculated for the logistic growth model was 0.945 for hens and 0.928 for cockerels and for the Gompertz growth model, 0.938 for hens and 0.924 for cockerels. The third-order polynomial fit gave R(2) of 0.938 for hens and 0.924 for cockerels. Among the Akaike information criterion calculations, the logistic growth model presented the lowest values in this study, both for hens and for cockerels. Nonlinear models are more appropriate for describing the sigmoid nature of ostrich growth.

Lower Neighborhood Socioeconomic Status Associated with Reduced Diversity of the Colonic Microbiota in Healthy Adults.

PubMed

Miller, Gregory E; Engen, Phillip A; Gillevet, Patrick M; Shaikh, Maliha; Sikaroodi, Masoumeh; Forsyth, Christopher B; Mutlu, Ece; Keshavarzian, Ali

2016-01-01

In the United States, there are persistent and widening socioeconomic gaps in morbidity and mortality from chronic diseases. Although most disparities research focuses on person-level socioeconomic-status, mounting evidence suggest that chronic diseases also pattern by the demographic characteristics of neighborhoods. Yet the biological mechanisms underlying these associations are poorly understood. There is increasing recognition that chronic diseases share common pathogenic features, some of which involve alterations in the composition, diversity, and functioning of the gut microbiota. This study examined whether socioeconomic-status was associated with alpha-diversity of the colonic microbiota. Forty-four healthy adults underwent un-prepped sigmoidoscopy, during which mucosal biopsies and fecal samples were collected. Subjects' zip codes were geocoded, and census data was used to form a composite indicator of neighborhood socioeconomic-status, reflecting household income, educational attainment, employment status, and home value. In unadjusted analyses, neighborhood socioeconomic-status explained 12-18 percent of the variability in alpha-diversity of colonic microbiota. The direction of these associations was positive, meaning that as neighborhood socioeconomic-status increased, so did alpha-diversity of both the colonic sigmoid mucosa and fecal microbiota. The strength of these associations persisted when models were expanded to include covariates reflecting potential demographic (age, gender, race/ethnicity) and lifestyle (adiposity, alcohol use, smoking) confounds. In these models neighborhood socioeconomic-status continued to explain 11-22 percent of the variability in diversity indicators. Further analyses suggested these patterns reflected socioeconomic variations in evenness, but not richness, of microbial communities residing in the sigmoid. We also found indications that residence in neighborhoods of higher socioeconomic-status was associated with a greater abundance of Bacteroides and a lower abundance of Prevotella, suggesting that diet potentially underlies differences in microbiota composition. These findings suggest the presence of socioeconomic variations in colonic microbiota diversity. Future research should explore whether these variations contribute to disparities in chronic disease outcomes.

[A case of unresectable colon cancer responding to oral leucovorin+oral tegafur/uracil].

PubMed

Saito, Naoto; Ohata, Masahiko; Ishii, Hiroshi; Ohori, Masaki; Tokura, Yasuyuki; Maruyama, Masanobu; Furukawa, Toshitaka; Sato, Hideaki

2007-08-01

The patient was a 63-year-old man,who first visited our hospital with the chief complaints of left lower quadrant pain and abdominal distension that had developed around November 13, 2004. On close examination, he was diagnosed with sigmoid colon cancer, multiple liver metastasis, and subileus due to a lung metastasis. His operation took place on December 12 of the same year. Intraoperatively, the sigmoid colon was firmly fixed to the retroperitonium, there was a hard node in the pouch of Douglas, and that part of the jejunum was involved. The lesion was judged to be unresectable,and thus loop colostomy, partial jejunectomy and gastrojejunostomy were performed. After the surgery,the patient was treated with 4 courses of therapy with oral Leucovorin (LV, 75 mg) +oral tegafur/uracil (UFT, 400 mg). As a result, the tumor marker levels decreased markedly, the lung metastasis was no longer observed and the liver metastases became smaller. Therefore, a second-look operation was performed on May 30, 2005. This time it was relatively easy to free the sigmoid colon. The node in the pouch of Douglas was no longer observed, and there were only 2 metastatic lesions in the liver (1 each in S 2 and S 6). Sigmoidectomy and partial hepatectomy were performed, and the stoma was closed. The patient made good progress after the operation and was discharged on the 11 th POD. At present he is receiving chemotherapy with UFT+oral LV as an outpatient. As this therapy is relatively easy to perform and imposes only a small burden on patients,we think that it may be effective not only as adjuvant chemotherapy but also as neoadjuvant chemotherapy in some patients.

Successive Homologous Coronal Mass Ejections Driven by Shearing and Converging Motions in Solar Active Region NOAA 12371

NASA Astrophysics Data System (ADS)

Vemareddy, P.

2017-08-01

We study the magnetic field evolution in AR 12371, related to its successive eruptive nature. During the disk transit of seven days, the active region (AR) launched four sequential fast coronal mass ejections (CMEs), which are associated with long duration M-class flares. Morphological study delineates a pre-eruptive coronal sigmoid structure above the polarity inversion line (PIL) similar to Moore et al.’s study. The velocity field derived from tracked magnetograms indicates persistent shear and converging motions of polarity regions about the PIL. While these shear motions continue, the crossed arms of two sigmoid elbows are being brought to interaction by converging motions at the middle of the PIL, initiating the tether-cutting reconnection of field lines and the onset of the CME explosion. The successive CMEs are explained by a cyclic process of magnetic energy storage and release referred to as “sigmoid-to-arcade-to-sigmoid” transformation driven by photospheric flux motions. Furthermore, the continued shear motions inject helicity flux with a dominant negative sign, which contributes to core field twist and its energy by building a twisted flux rope (FR). After a limiting value, the excess coronal helicity is expelled by bodily ejection of the FR, which is initiated by some instability as realized by intermittent CMEs. This AR is in contrast with the confined AR 12192 with a predominant negative sign and larger helicity flux, but much weaker (-0.02 turns) normalized coronal helicity content. While predominant signed helicity flux is a requirement for CME eruption, our study suggests that the magnetic flux normalized helicity flux is a necessary condition accommodating the role of background flux and appeals to a further study of a large sample of ARs.

[Dolichomegacolon of the Andes and intestinal volvulus due to altitude].

PubMed

Frisancho, Oscar

2008-01-01

Sigmoid volvulus is a frequent cause of emergencies in hospitals in the Andean area, representing more than 50% of all intestinal obstructions. Andean dolichomegacolon (DCMA) and retractile mesocolonitis are the main contributing factors for volvulus. The mesocolonitis nears the proximal and distal segment of the sigmoid handle, favoring its torsion. Copious intake of fermentable food is the precipitating factor for volvulus. The majority of patients are seen during sowing and harvest periods, in which the consumption of this type of food increases. Andean people who live at an altitude of 3,000 m have a larger and thicker colon than coastal residents. We call this acquired characteristic the Andean dolichomegacolon (DCMA). A fiber-rich diet may inhibit the histological phenomenon known as elastogenesis, developing--over the years--the megacolon. Another important factor may be the lower atmospheric pressure in the altitude, and according to Boyle and Mariotte's physical law, the expansion of intraluminal gas may have an influence on intestinal enlargement. DCMA has many special anatomic, clinical, radiological, histological and serological features which make it different from the . chagasic megacolon. Mild emergency procedures may be performed to treat the sigmoid volvulus, such as endoscopic disvolvulation. Changing the colon rotation is helpful in diminishing abdominal pressure and restore complete blood circulation. An emergency surgery treatment must take the patient's general condition and the colon handle condition during surgery as a guiding point. High rates of mortality are found in relation to elderly patients, disease evolution time and stage of intestinal ischemia. Other new therapeutic procedures such as percutaneous sigmoidpexy, laparoscopic sigmoidectomy and mesosigmoplasty are under review, and have precise indications. Wider series are needed to evaluate them better.

Transarterial Onyx embolization of intracranial dural arteriovenous fistulas: a single center experience.

PubMed

Luo, Chao-Bao; Chang, Feng-Chi; Mu-Huo Teng, Michael; Lin, Chung-Jung; Wu, Hsiu-Mei; Guo, Wan-Yuo; Chang, Cheng-Yen

2014-04-01

Transarterial embolization of intracranial dural arteriovenous fistulas (DAVFs) is usually associated with inadequate embolization. The purpose of this study was to report our experience of transarterial Onyx embolization of intracranial DAVFs with an emphasis on treatment outcome with this new embolic agent in different types of DAVFs. In the past 3 years, a total of 14 intracranial DAVFs have been treated by transarterial Onyx embolization. Among these, there were nine males and five females, aged from 30 years to 82 years (mean = 62 years). We retrospectively analyzed the injection volume and time of Onyx embolization as well as outcomes in different types of DAVFs. The locations of the DAVFs were sigmoid sinus (n = 6), tentorium (n = 3), sinus confluence (n = 2), transverse-sigmoid sinus (n = 1), sigmoid sinus-jugular bulb (n = 1) and the superior petrous sinus (n = 1). The mean volume and time of Onyx injection were 3.4 mL and 28 minutes, respectively (Cognard type I: 4.9 mL, 40 minutes; type II: 4.5 mL, 34 minutes; type III: 2.2 mL, 21 minutes; type IV: 2 mL, 22 minutes). Total fistula occlusion was achieved in six out of seven patients of type III and type IV DAVFs, and in four out of seven patients of type I and type II DAVFs. Nine patients had total resolution of their symptoms, whereas partial regression occurred in five patients. No significant periprocedural complication was found. Mean clinical follow-up period was 16 months. Transarterial Onyx embolization of intracranial DAVFs is safe and effective. This technique is particularly useful in type III and type IV DAVFs with a high cure rate, and lower volume of Onyx as well as a short injection time. Copyright © 2014. Published by Elsevier B.V.

Surgical management of recto-sigmoid Hirschsprung's disease.

PubMed

Nouira, F; Ben Ahmed, Y; Sarrai, N; Ghorbel, S; Jlidi, S; Khemakhem, R; Charieg, A; Chaouachi, B

2012-01-01

Over the years, the surgical management of recto-sigmoid Hirschsprung's disease (HD) has evolved radically and at present a single stage transanal pull-through can be done in suitable cases, which obviates the need for multiple surgeries. The aim of this paper was to evaluate the role of transanal pull-through in the management of recto-sigmoid HD in our institution. A retrospective analysis (between January 2003 and December 2009) was carried out on all cases of Hirschsprung's reporting to unity of pediatric surgery of Tunis Children's Hospital that were managed by transanal pull-through as a definitive treatment. All selected patients including neonates had an aganglionic segment confined to the rectosigmoid area, confirmed by preoperative barium enema and postoperative histology. Twenty-six children (86%) had their operation done without construction of prior colostomy. Transanal pull-through was performed in 31 children. Mean operating time was 150 minutes (range 64 to 300 minutes). No patients required laparotomy because all patients including neonates had an aganglionic segment confined to the rectosigmoid area. Blood loss ranged between 20 to 56 ml without blood replacement. Since all children were given an epidural caudal block, the requirement of analgesia in these cases was minimal. Postoperative complications included perianal excoriation in 7 out of 31 patients lasting from 3 weeks to 6 months. Complete anorectal continence was noted in 21 of 31 (67%) children in follow up of 3-5 years. Transanal endorectal pull-through procedure for the management of rectosigmoid HD is now a well-established and preferred approach. Parental satisfaction is immense due to the lack of scars on the abdomen. As regards the continence, a long-term follow-up is necessary to appreciate better the functional results of this surgery.

Successive Homologous Coronal Mass Ejections Driven by Shearing and Converging Motions in Solar Active Region NOAA 12371

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vemareddy, P., E-mail: vemareddy@iiap.res.in

We study the magnetic field evolution in AR 12371, related to its successive eruptive nature. During the disk transit of seven days, the active region (AR) launched four sequential fast coronal mass ejections (CMEs), which are associated with long duration M-class flares. Morphological study delineates a pre-eruptive coronal sigmoid structure above the polarity inversion line (PIL) similar to Moore et al.’s study. The velocity field derived from tracked magnetograms indicates persistent shear and converging motions of polarity regions about the PIL. While these shear motions continue, the crossed arms of two sigmoid elbows are being brought to interaction by convergingmore » motions at the middle of the PIL, initiating the tether-cutting reconnection of field lines and the onset of the CME explosion. The successive CMEs are explained by a cyclic process of magnetic energy storage and release referred to as “sigmoid-to-arcade-to-sigmoid” transformation driven by photospheric flux motions. Furthermore, the continued shear motions inject helicity flux with a dominant negative sign, which contributes to core field twist and its energy by building a twisted flux rope (FR). After a limiting value, the excess coronal helicity is expelled by bodily ejection of the FR, which is initiated by some instability as realized by intermittent CMEs. This AR is in contrast with the confined AR 12192 with a predominant negative sign and larger helicity flux, but much weaker (−0.02 turns) normalized coronal helicity content. While predominant signed helicity flux is a requirement for CME eruption, our study suggests that the magnetic flux normalized helicity flux is a necessary condition accommodating the role of background flux and appeals to a further study of a large sample of ARs.« less

Is laparoscopic surgery the best treatment in fistulas complicating diverticular disease of the sigmoid colon? A systematic review.

PubMed

Cirocchi, Roberto; Arezzo, Alberto; Renzi, Claudio; Cochetti, Giovanni; D'Andrea, Vito; Fingerhut, Abe; Mearini, Ettore; Binda, Gian Andrea

2015-12-01

Laparoscopic surgery is considered in the treatment of diverticular fistula for the possible reduction of overall morbidity and complication rate if compared to open surgery. Aim of this review is to assess the possible advantages deriving from a laparoscopic approach in the treatment of diverticular fistulas of the colon. Studies presenting at least 10 adult patients who underwent laparoscopic surgery for sigmoid diverticular fistula were reviewed. Fistula recurrence, reintervention, Hartmann's procedure or proximal diversion, conversion to laparotomy were the outcomes considered. 11 non randomized studies were included. Rates of fistula recurrence (0.8%), early reintervention (30 days) (2%) and need for Hartmann's procedure or proximal diversion (1.4%) did not show significant difference between laparoscopy and open technique. there is still concern about which surgery in complicated diverticulitis should be preferred. Laparoscopic approach has led to less postoperative pain, shorter hospital stay, faster recovery and better cosmetic results. Laparoscopic resection and primary anastomosis is a possible approach to sigmoid fistulas but its advantages in terms of lower mortality rate and postoperative stay after colon resection with primary anastomosis should be interpreted with caution. When there is firm evidence supporting it, it is likely that minimally invasive surgery should become the standard approach for diverticular fistulas, thus achieving adequate exposure and better visualization of the surgical field. The lack of RCTs, the small sample size, the heterogeneity of literature do not allow to draw statistically significant conclusions on the laparoscopic surgery for fistulas despite this approach is considered safe. Copyright © 2015 IJS Publishing Group Limited. Published by Elsevier Ltd. All rights reserved.

Limited evidence of abnormal intra-colonic pressure profiles in diverticular disease - a systematic review.

PubMed

Jaung, R; Robertson, J; O'Grady, G; Milne, T; Rowbotham, D; Bissett, I P

2017-06-01

Abnormal colonic pressure profiles and high intraluminal pressures are postulated to contribute to the formation of sigmoid colon diverticulosis and the pathophysiology of diverticular disease. This study aimed to review evidence for abnormal colonic pressure profiles in diverticulosis. All published studies investigating colonic pressure in patients with diverticulosis were searched in three databases (Medline, Embase, Scopus). No language restrictions were applied. Any manometry studies in which patients with diverticulosis were compared with controls were included. The Newcastle-Ottawa Quality Assessment Scale (NOS) for case-control studies was used as a measure of risk of bias. A cut-off of five or more points on the NOS (fair quality in terms of risk of bias) was chosen for inclusion in the meta-analysis. Ten studies (published 1962-2005) met the inclusion criteria. The studies followed a wide variety of protocols and all used low-resolution manometry (sensor spacing range 7.5-15 cm). Six studies compared intra-sigmoid pressure, with five of six showing higher pressure in diverticulosis vs controls, but only two reached statistical significance. A meta-analysis was not performed as only two studies were above the cut-off and these did not have comparable outcomes. This systematic review of manometry data shows that evidence for abnormal pressure in the sigmoid colon in patients with diverticulosis is weak. Existing studies utilized inconsistent methodology, showed heterogeneous results and are of limited quality. Higher quality studies using modern manometric techniques and standardized reporting methods are needed to clarify the role of colonic pressure in diverticulosis. Colorectal Disease © 2017 The Association of Coloproctology of Great Britain and Ireland.

Milk marketing policy options for the dairy industry in New England.

PubMed

Doyon, M; Criner, G; Bragg, L A

2008-03-01

New England dairy farmers are under intense price pressure resulting from important growth in milk production from lower cost of production Southwest states as well as by retailers' market power. Agricultural officials and legislative bodies in New England and in other Northeast US states are aware of these pressures and have been reacting with emergency dairy farm aid, following a very low 2006 milk price, and with state legislations in an attempt to address perceived excess retailing margins for fluid milk. In this paper, we suggest that a sigmoid demand relationship exists for fluid milk. This demand relationship would explain fluid milk asymmetric price transmission, high-low pricing, and the creation of a large retailing margin (chain surplus) often observed for fluid milk. It is also argued that a sigmoid demand relationship offers an opportunity for state legislators to help Northeast dairy farmers capturing a larger share of the dollar of the consumers through various policy options. Therefore, 5 milk market channel regulatory mechanisms (status quo, price gouging, supply control, fair share policy, and chain surplus return) are discussed and compared. The supply control mechanism was found the most effective at redistributing the chain surplus, associated with the sigmoid demand relationship for fluid milk, to dairy farmers. However, this option is unlikely to be politically acceptable in the United States. Second-best options for increasing dairy farmers' share of the consumers' dollar are the fair price policy and the chain surplus return. The former mechanism would distribute the chain surplus between retailers, processors, and farmers, whereas the latter would distribute it between consumers, retailers, and farmers. Remaining mechanisms would either transfer the chain surplus to retailers (status quo) or to consumers (price gouging).

The cerebrovascular response to carbon dioxide in humans

PubMed Central

Battisti-Charbonney, A; Fisher, J; Duffin, J

2011-01-01

Abstract Carbon dioxide (CO2) increases cerebral blood flow and arterial blood pressure. Cerebral blood flow increases not only due to the vasodilating effect of CO2 but also because of the increased perfusion pressure after autoregulation is exhausted. Our objective was to measure the responses of both middle cerebral artery velocity (MCAv) and mean arterial blood pressure (MAP) to CO2 in human subjects using Duffin-type isoxic rebreathing tests. Comparisons of isoxic hyperoxic with isoxic hypoxic tests enabled the effect of oxygen tension to be determined. During rebreathing the MCAv response to CO2 was sigmoidal below a discernible threshold CO2 tension, increasing from a hypocapnic minimum to a hypercapnic maximum. In most subjects this threshold corresponded with the CO2 tension at which MAP began to increase. Above this threshold both MCAv and MAP increased linearly with CO2 tension. The sigmoidal MCAv response was centred at a CO2 tension close to normal resting values (overall mean 36 mmHg). While hypoxia increased the hypercapnic maximum percentage increase in MCAv with CO2 (overall means from 76.5 to 108%) it did not affect other sigmoid parameters. Hypoxia also did not alter the supra-threshold MCAv and MAP responses to CO2 (overall mean slopes 5.5% mmHg-1 and 2.1 mmHg mmHg−1, respectively), but did reduce the threshold (overall means from 51.5 to 46.8 mmHg). We concluded that in the MCAv response range below the threshold for the increase of MAP with CO2, the MCAv measurement reflects vascular reactivity to CO2 alone at a constant MAP. PMID:21521758

Types and Indications of Colostomy and Determinants of Outcomes of Patients After Surgery.

PubMed

Engida, Abebe; Ayelign, Tsehay; Mahteme, Bekele; Aida, Tilahun; Abreham, Berhane

2016-03-01

Colostomy is one of the commonest life saving procedures done worldwide with an intention of either decompression of an obstructed colon or diversion of stool. Indications may vary from region to region. Attending morbidity and mortality is significant. the objective of this study was to Determine the common indications and types of colostomy, and outcomes of patients operated at SPHMMC. A retrospective medical records of patients, operation log book and nursing records review was done in a two-year period between January 2011 and December 2013 at the College Teaching Hospital, St Paul's Hospital Millennium Medical, Addis Ababa. During the two years, 253 colostomies were done and 219(86.6%) cases used for analysis. Of these, 151(68.9%) were males. Age ranged from 15 to 85 years with a mean of 50.8. Most of the surgeries, 196(89.5%), were done for emergency conditions. The three most common indications were gangrenous sigmoid volvulus, 102(46.6%), colorectal cancers, 46(21.0%, and abdominal injuries, 28(12.8%). The commonest type of colostomy done was Hartman's colostomy, 179(81.7.1%), gangrenous sigmoid volvulus being the predominant indication, 102(57%). Loop colostomy constituted 35(16%) of all the colostomies. Penetrating abdominal injuries was the main indication 15(42.9%). Overall, 157 complications were seen on 106(48.4%) patients. The most common complications were surgical site infection, 51(23.3%), hospital acquired pneumonia, (10.5%), and wound dehiscence, 17(7.8%). The mortality rate was 9.6% (21). Gangrenous sigmoid volvulus is the leading indication for colostomy. Mortality and morbidity rates are high. Aggressive resuscitation, early prompt operation and post op close follow-up should be emphasized.

INITIATION AND ERUPTION PROCESS OF MAGNETIC FLUX ROPE FROM SOLAR ACTIVE REGION NOAA 11719 TO EARTH-DIRECTED CME

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vemareddy, P.; Zhang, J., E-mail: vema@prl.res.in

An eruption event launched from the solar active region (AR) NOAA 11719 is investigated based on coronal EUV observations and photospheric magnetic field measurements obtained from the Solar Dynamic Observatory. The AR consists of a filament channel originating from a major sunspot and its south section is associated with an inverse-S sigmoidal system as observed in Atmospheric Imaging Assembly passbands. We regard the sigmoid as the main body of the flux rope (FR). There also exists a twisted flux bundle crossing over this FR. This overlying flux bundle transforms in shape similar to kink-rise evolution, which corresponds with the risemore » motion of the FR. The emission measure and temperature along the FR exhibits an increasing trend with its rising motion, indicating reconnection in the thinning current sheet underneath the FR. Net magnetic flux of the AR, evaluated at north and south polarities, showed decreasing behavior whereas the net current in these fluxes exhibits an increasing trend. Because the negative (positive) flux has a dominant positive (negative) current, the chirality of AR flux system is likely negative (left handed) in order to be consistent with the chirality of inverse S-sigmoidal FR. This analysis of magnetic fields of the source AR suggests that the cancelling fluxes are prime factors of the monotonous twisting of the FR system, reaching to a critical state to trigger kink instability and rise motion. This rise motion may have led to the onset of the torus instability, resulting in an Earth-directed coronal mass ejection, and the progressive reconnection in the thinning current sheet beneath the rising FR led to the M6.5 flare.« less

A new method to compare statistical tree growth curves: the PL-GMANOVA model and its application with dendrochronological data.

PubMed

Ricker, Martin; Peña Ramírez, Víctor M; von Rosen, Dietrich

2014-01-01

Growth curves are monotonically increasing functions that measure repeatedly the same subjects over time. The classical growth curve model in the statistical literature is the Generalized Multivariate Analysis of Variance (GMANOVA) model. In order to model the tree trunk radius (r) over time (t) of trees on different sites, GMANOVA is combined here with the adapted PL regression model Q = A · T+E, where for b ≠ 0 : Q = Ei[-b · r]-Ei[-b · r1] and for b = 0 : Q  = Ln[r/r1], A =  initial relative growth to be estimated, T = t-t1, and E is an error term for each tree and time point. Furthermore, Ei[-b · r]  = ∫(Exp[-b · r]/r)dr, b = -1/TPR, with TPR being the turning point radius in a sigmoid curve, and r1 at t1 is an estimated calibrating time-radius point. Advantages of the approach are that growth rates can be compared among growth curves with different turning point radiuses and different starting points, hidden outliers are easily detectable, the method is statistically robust, and heteroscedasticity of the residuals among time points is allowed. The model was implemented with dendrochronological data of 235 Pinus montezumae trees on ten Mexican volcano sites to calculate comparison intervals for the estimated initial relative growth A. One site (at the Popocatépetl volcano) stood out, with A being 3.9 times the value of the site with the slowest-growing trees. Calculating variance components for the initial relative growth, 34% of the growth variation was found among sites, 31% among trees, and 35% over time. Without the Popocatépetl site, the numbers changed to 7%, 42%, and 51%. Further explanation of differences in growth would need to focus on factors that vary within sites and over time.

Bethe lattice approach and relaxation dynamics study of spin-crossover materials

NASA Astrophysics Data System (ADS)

Oke, Toussaint Djidjoho; Hontinfinde, Félix; Boukheddaden, Kamel

2015-07-01

Dynamical properties of Prussian blue analogs and spin-crossover materials are investigated in the framework of a Blume-Emery-Griffiths (BEG) spin-1 model, where states ±1 and 0 represent the high-spin (HS) state and the low-spin state, respectively. The quadrupolar interaction depends on the temperature in the form . Magnetic interactions are controlled by a factor such that for (), magnetic ordering is not expected. The model is exactly solved using the Bethe lattice approach for the equilibrium properties. The results are closer to those calculated by numerical simulations with suitable Arrhenius-type transition rates. The study of relaxation processes of non-equilibrium HS states revealed one-step nonlinear sigmoidal relaxation curves of the HS fraction at low temperatures. We found that increasing the magnetic interactions leads to the appearance of a plateau in the thermal hysteresis as well as in the relaxation curves of the HS fraction at low temperature.

An integrated approach to model strain localization bands in magnesium alloys

NASA Astrophysics Data System (ADS)

Baxevanakis, K. P.; Mo, C.; Cabal, M.; Kontsos, A.

2018-02-01

Strain localization bands (SLBs) that appear at early stages of deformation of magnesium alloys have been recently associated with heterogeneous activation of deformation twinning. Experimental evidence has demonstrated that such "Lüders-type" band formations dominate the overall mechanical behavior of these alloys resulting in sigmoidal type stress-strain curves with a distinct plateau followed by pronounced anisotropic hardening. To evaluate the role of SLB formation on the local and global mechanical behavior of magnesium alloys, an integrated experimental/computational approach is presented. The computational part is developed based on custom subroutines implemented in a finite element method that combine a plasticity model with a stiffness degradation approach. Specific inputs from the characterization and testing measurements to the computational approach are discussed while the numerical results are validated against such available experimental information, confirming the existence of load drops and the intensification of strain accumulation at the time of SLB initiation.

Active Dendrites Enhance Neuronal Dynamic Range

PubMed Central

Gollo, Leonardo L.; Kinouchi, Osame; Copelli, Mauro

2009-01-01

Since the first experimental evidences of active conductances in dendrites, most neurons have been shown to exhibit dendritic excitability through the expression of a variety of voltage-gated ion channels. However, despite experimental and theoretical efforts undertaken in the past decades, the role of this excitability for some kind of dendritic computation has remained elusive. Here we show that, owing to very general properties of excitable media, the average output of a model of an active dendritic tree is a highly non-linear function of its afferent rate, attaining extremely large dynamic ranges (above 50 dB). Moreover, the model yields double-sigmoid response functions as experimentally observed in retinal ganglion cells. We claim that enhancement of dynamic range is the primary functional role of active dendritic conductances. We predict that neurons with larger dendritic trees should have larger dynamic range and that blocking of active conductances should lead to a decrease in dynamic range. PMID:19521531

A dose-responsive model of smoke inhalation injury. Severity-related alteration in cardiopulmonary function.

PubMed Central

Shimazu, T; Yukioka, T; Hubbard, G B; Langlinais, P C; Mason, A D; Pruitt, B A

1987-01-01

The dose responsiveness of selected physiologic indices was studied in a sheep model of smoke inhalation injury. In this model, graded severity of injury was achieved by changing the contact time with smoke (defined by "unit"), whereas other variables were kept constant. Blood gas and cardiopulmonary indices were measured in 70 sheep, including 12 controls, either 24 or 72 hours after exposure to 3, 6, 9, 12, 15, or 18 units of smoke. A 12-unit dose of smoke was fatal within 72 hours and an 18-unit dose was fatal within 24 hours. The best correlation between smoke dose and response was observed in arterial oxygen tension 24 hours after exposure. At 24 hours, most of the cardiopulmonary indices showed significant change only after a 12-unit exposure. Although the exact shape of the dose-response curve could not be defined, sigmoid or curved linear shape was suggested, reflecting the progressive deterioration. Images Fig. 3. Fig. 4A. Fig. 4B. PMID:3606236

Airborne Detection and Tracking of Geologic Leakage Sites

NASA Astrophysics Data System (ADS)

Jacob, Jamey; Allamraju, Rakshit; Axelrod, Allan; Brown, Calvin; Chowdhary, Girish; Mitchell, Taylor

2014-11-01

Safe storage of CO2 to reduce greenhouse gas emissions without adversely affecting energy use or hindering economic growth requires development of monitoring technology that is capable of validating storage permanence while ensuring the integrity of sequestration operations. Soil gas monitoring has difficulty accurately distinguishing gas flux signals related to leakage from those associated with meteorologically driven changes of soil moisture and temperature. Integrated ground and airborne monitoring systems are being deployed capable of directly detecting CO2 concentration in storage sites. Two complimentary approaches to detecting leaks in the carbon sequestration fields are presented. The first approach focuses on reducing the requisite network communication for fusing individual Gaussian Process (GP) CO2 sensing models into a global GP CO2 model. The GP fusion approach learns how to optimally allocate the static and mobile sensors. The second approach leverages a hierarchical GP-Sigmoidal Gaussian Cox Process for airborne predictive mission planning to optimally reducing the entropy of the global CO2 model. Results from the approaches will be presented.

Metastable dynamical patterns and their stabilization in arrays of bidirectionally coupled sigmoidal neurons

NASA Astrophysics Data System (ADS)

Horikawa, Yo

2013-12-01

Transient patterns in a bistable ring of bidirectionally coupled sigmoidal neurons were studied. When the system had a pair of spatially uniform steady solutions, the instability of unstable spatially nonuniform steady solutions decreased exponentially with the number of neurons because of the symmetry of the system. As a result, transient spatially nonuniform patterns showed dynamical metastability: Their duration increased exponentially with the number of neurons and the duration of randomly generated patterns obeyed a power-law distribution. However, these metastable dynamical patterns were easily stabilized in the presence of small variations in coupling strength. Metastable rotating waves and their pinning in the presence of asymmetry in the direction of coupling and the disappearance of metastable dynamical patterns due to asymmetry in the output function of a neuron were also examined. Further, in a two-dimensional array of neurons with nearest-neighbor coupling, intrinsically one-dimensional patterns were dominant in transients, and self-excitation in these neurons affected the metastable dynamical patterns.

The silent mutation MLH1 c.543C>T resulting in aberrant splicing can cause Lynch syndrome: a case report.

PubMed

Yamaguchi, Tatsuro; Wakatsuki, Tomokazu; Kikuchi, Mari; Horiguchi, Shin-Ichiro; Akagi, Kiwamu

2017-06-01

The proband was a 67-year-old man with transverse and sigmoid colon cancer. Microsatellite instability analysis revealed a high frequency of microsatellite instability, and immunohistochemical staining showed the absence of both MLH1 and PMS2 proteins in the sigmoid colon cancer tissue specimens from the patient. DNA sequencing revealed a nucleotide substitution c.543C>T in MLH1, but this variant did not substitute an amino acid. The MLH1 c.543C>T variant was located 3 bases upstream from the end of exon 6 and created a new splice donor site 4 bases upstream from the end of exon 6. Consequently, the last 4 bases of exon 6 were deleted and frameshift occurred. Thus, the MLH1 c.543C>T silent mutation is considered 'pathogenic'. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

MHD simulations of homologous and cannibalistic coronal mass ejections

NASA Astrophysics Data System (ADS)

Fan, Yuhong; Chatterjee, Piyali

2014-06-01

We present magneto-hydrodynamic simulations of the development of a homologous sequence of coronal mass ejections (CMEs) and demonstrate their so-called cannibalistic behavior. These CMEs originate from the repeated formations and partial eruptions of kink unstable flux ropes as a result of the continued emergence of a twisted flux rope across the lower boundary into a pre-existing coronal potential arcade field. The simulations show that a CME erupting into the open magnetic field created by a preceding CME has a higher speed, and therefore tends to be cannibalistic, catching up and merging with the preceding one into a single fast CME. All the CMEs attained speeds of about 1000 km/s as they exit the domain. The reformation of a twisted flux rope after each CME eruption during the sustained flux emergence can naturally explain the X-ray observations of repeated reformations of sigmoids and “sigmoid-under-cusp” configurations at a low-coronal source of homologous CMEs.

Bilateral chondrosarcoma of the jugular foramen: literature review and personal experience.

PubMed

Zanoletti, Elisabetta; Faccioli, Chiara; Cazzador, Diego; Mazzoni, Antonio; Martini, Alessandro

2015-10-01

Chondrosarcomas (CS) are slow-growing malignant cartilaginous tumors with locally invasive behavior. They account for only 0.15% head and neck neoplasia. There have been no reports in the management of bilateral skull base CS in the literature to date. The synchronous presentation of bilateral CS of the jugular foramen (JF) was diagnosed in a 22-year-old woman with right abducens nerve palsy. Once evaluated the collateral intracranial venous discharge, the lesions were removed in two surgical stages through a bilateral petro-occipital trans-sigmoid (POTS) approach performing a bilateral closure of sigmoid sinus. The patient is disease free 15 years after surgery. No complications occurred. Diplopia improved after excision of the tumor on the right side. A review of relevant English literature was performed. The POTS approach to the JF proved to be safe and effective. Staged radical surgery alone, assessing intracranial venous flow at all stages of surgery, was a valid strategy for bilateral CS, achieving long-term disease control, avoiding early adjuvant radiotherapy, and carrying no complications.

Pathological complete response following neoadjuvant radiotherapy and intraperitoneal perfusion chemotherapy for recurrent colon carcinoma: A case report and literature review

PubMed Central

BIAN, XINYU; LIU, BAORUI; YANG, YANG

2016-01-01

The present study reports the case of a 28-year-old male who was diagnosed with sigmoid colon carcinoma and exhibited local recurrence following radical surgery and 6 cycles of adjuvant chemotherapy. The primary surgery consisted of a partial sigmoidectomy and bladder repair. At 8 months post-chemotherapy, the patient was referred to Nanjing Drum Tower Hospital (Nanjing, China) due to local recurrence at the anastomotic site, which was confirmed by colonoscopy and total abdominal computed tomography. Synchronous intensity modulation radiation therapy and intraperitoneal (IP) perfusion chemotherapy with irinotecan (100 mg/m2) was administered. Following treatment, the object efficacy evaluation revealed a complete response and a second resection of the remaining sigmoid colon was performed. The post-operative results showed a pathological complete response. This case indicated that a combination of therapies, including radiotherapy, IP perfusion chemotherapy and surgery, may be beneficial and effective in patients with recurrent colon cancer. PMID:27073546

Bio-Inspired Microsystem for Robust Genetic Assay Recognition

PubMed Central

Lue, Jaw-Chyng; Fang, Wai-Chi

2008-01-01

A compact integrated system-on-chip (SoC) architecture solution for robust, real-time, and on-site genetic analysis has been proposed. This microsystem solution is noise-tolerable and suitable for analyzing the weak fluorescence patterns from a PCR prepared dual-labeled DNA microchip assay. In the architecture, a preceding VLSI differential logarithm microchip is designed for effectively computing the logarithm of the normalized input fluorescence signals. A posterior VLSI artificial neural network (ANN) processor chip is used for analyzing the processed signals from the differential logarithm stage. A single-channel logarithmic circuit was fabricated and characterized. A prototype ANN chip with unsupervised winner-take-all (WTA) function was designed, fabricated, and tested. An ANN learning algorithm using a novel sigmoid-logarithmic transfer function based on the supervised backpropagation (BP) algorithm is proposed for robustly recognizing low-intensity patterns. Our results show that the trained new ANN can recognize low-fluorescence patterns better than an ANN using the conventional sigmoid function. PMID:18566679

Development and implementation of a virtual reality laparoscopic colorectal training curriculum.

PubMed

Wynn, Greg; Lykoudis, Panagis; Berlingieri, Pasquale

2017-12-12

Contemporary surgical training can be compromised by fewer practical opportunities. Simulation can fill this gap to optimize skills' development and progress monitoring. A structured virtual reality (VR) laparoscopic sigmoid colectomy curriculum is constructed and its validity and outcomes assessed. Parameters and thresholds were defined by analysing the performance of six expert surgeons completing the relevant module on the LAP Mentor simulator. Fourteen surgical trainees followed the curriculum, performance being recorded and analysed. Evidence of validity was assessed. Time to complete procedure, number of movements of right and left instrument, and total path length of right and left instrument movements demonstrated evidence of validity and clear learning curves, with a median of 14 attempts needed to complete the curriculum. A structured curriculum is proposed for training in laparoscopic sigmoid colectomy in a VR environment based on objective metrics in addition to expert consensus. Validity has been demonstrated for some key metrics. Copyright © 2017 Elsevier Inc. All rights reserved.

Smoking increases the incidence of complicated diverticular disease of the sigmoid colon.

PubMed

Turunen, P; Wikström, H; Carpelan-Holmström, M; Kairaluoma, P; Kruuna, O; Scheinin, T

2010-01-01

The aim of this study was to establish whether smoking is associated with complicated diverticular disease and adverse outcomes of operative treatment of diverticular disease. Smoking has been associated with increased rate of perforations in acute appendicitis as well as failure of colonic anastomosis in patients resected for colonic tumours. It has also been suggested that smoking is a risk factor for complicated diverticular disease of the colon. Retrospective investigation of records of 261 patients electively operated for diverticular disease in Helsinki University Central Hospital during a period of five years. The smokers underwent sigmoidectomy at a younger age than the non-smokers (p = 0.001) and they had an increased rate of perforations (p = 0.040) and postoperative recurrent diverticulitis episodes (p = 0.019). We conclude that smoking increases the likelihood of complications in diverticulosis coli. The development of complicated disease also seems to proceed more rapidly in smokers.Key words: Sigmoid resection; laparoscopy; laparoscopic sigmoidectomy; smoking and diverticular disease; complicated diverticular disease; diverticulitis.

Inguinoscrotal hernia containing the urinary bladder successfully repaired using laparoscopic transabdominal preperitoneal repair technique: A case report.

PubMed

Tazaki, Tatsuya; Sasaki, Masaru; Kohyama, Mohei; Sugiyama, Yoichi; Uegami, Shinnosuke; Shintakuya, Ryuta; Imamura, Yuji; Nakamitsu, Atsushi

2018-05-23

We report herein a patient with an inguinoscrotal hernia containing the urinary bladder. The hernia was safely repaired using the laparoscopic transabdominal preperitoneal repair technique. A 76-year-old man was admitted to our hospital with abdominal pain, vomiting, and diarrhea. His scrotum was swollen to fist size. Abdominal CT showed herniation of the sigmoid colon and the bladder into the right inguinal region, and his abdominal pain was attributed to incarceration of the sigmoid colon; this was manually reduced. About 1 month later, we performed transabdominal preperitoneal repair. After the direct hernial orifice was identified, the bladder was noted to be sliding from the medial side of the hernia; this was reduced. Peeling on the medial side was carried out to the middle of the abdominal wall, and the myopectineal orifice was covered with mesh. The patient was discharged on postoperative day 1. © 2018 Japan Society for Endoscopic Surgery, Asia Endosurgery Task Force and John Wiley & Sons Australia, Ltd.

Large tubular colonic duplication in an adult treated with a small midline incision

PubMed Central

Yong, Yuen Geng; Jung, Kyung Uk; Cho, Yong Beom; Yun, Seong Hyeon; Kim, Hee Cheol; Lee, Woo Yong

2012-01-01

Tubular colonic duplication presenting in adults is rare and difficult to diagnose preoperatively. Only a few cases have been reported in the literature. We report a case of a 29-year-old lady presenting with a long history of chronic constipation, abdominal mass and repeated episodes of abdominal pain. The abdominal-pelvic computed tomography scan showed segmental bowel wall thickening thought to be small bowel, and dilatation with stasis of intraluminal content. The provisional diagnosis was small bowel duplication. She was scheduled for single port laparoscopic resection. However, a T-shaped tubular colonic duplication at sigmoid colon was found intraoperatively. Resection of the large T-shaped tubular colonic duplication containing multiple impacted large fecaloma and primary anastomosis was performed. There was no perioperative complication. We report, herein, the case of a T-shaped tubular colonic duplication at sigmoid colon in an adult who was successfully treated through mini-laparotomy assisted by single port laparoscopic surgery. PMID:22403754

Deep infiltrating endometriosis: Should rectal and vaginal opacification be systematically used in MR imaging?

PubMed

Uyttenhove, F; Langlois, C; Collinet, P; Rubod, C; Verpillat, P; Bigot, J; Kerdraon, O; Faye, N

2016-06-01

To evaluate the interest of rectal and vaginal filling in vaginal and recto-sigmoid endometriosis with MR imaging. To compare the results between a senior and a junior radiologist review. Sixty-seven patients with clinically suspected deep infiltrating endometriosis were included in our MRI protocol consisting of repeated T2-weigthed sequences (axial and sagittal) before and after rectal and vaginal marking with ultrasonography gel. Vaginal and recto-sigmoid endometriosis lesions were analyzed before and after opacification. The inter-reader agreement between senior and junior scores was studied. Concerning vaginal and muscularis and beyond colonic involvement, no significant difference (P=0.32) was observed and the inter-reader agreement was excellent (K=0.96 and 0.97 respectively). Concerning serosa colonic lesions, a significant difference was observed (P=0.01) and the inter-reader agreement was poor (K=0). Rectal and vaginal filling in endometriosis staging with MRI is not necessary no matter the reader experiment. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Time to Completion of Web-Based Physics Problems with Tutoring

PubMed Central

Warnakulasooriya, Rasil; Palazzo, David J; Pritchard, David E

2007-01-01

We studied students performing a complex learning task, that of solving multipart physics problems with interactive tutoring on the web. We extracted the rate of completion and fraction completed as a function of time on task by retrospectively analyzing the log of student–tutor interactions. There was a spontaneous division of students into three groups, the central (and largest) group (about 65% of the students) being those who solved the problem in real time after multiple interactions with the tutorial program (primarily receiving feedback to submitted wrong answers and requesting hints). This group displayed a sigmoidal fraction-completed curve as a function of logarithmic time. The sigmoidal shape is qualitatively flatter for problems that do not include hints and wrong-answer responses. We argue that the group of students who respond quickly (about 10% of the students) is obtaining the answer from some outside source. The third group (about 25% of the students) represents those who interrupt their solution, presumably to work offline or to obtain outside help. PMID:17725054

Segmentation algorithm of colon based on multi-slice CT colonography

NASA Astrophysics Data System (ADS)

Hu, Yizhong; Ahamed, Mohammed Shabbir; Takahashi, Eiji; Suzuki, Hidenobu; Kawata, Yoshiki; Niki, Noboru; Suzuki, Masahiro; Iinuma, Gen; Moriyama, Noriyuki

2012-02-01

CT colonography is a radiology test that looks at people's large intestines(colon). CT colonography can screen many options of colon cancer. This test is used to detect polyps or cancers of the colon. CT colonography is safe and reliable. It can be used if people are too sick to undergo other forms of colon cancer screening. In our research, we proposed a method for automatic segmentation of the colon from abdominal computed Tomography (CT) images. Our multistage detection method extracted colon and spited colon into different parts according to the colon anatomy information. We found that among the five segmented parts of the colon, sigmoid (20%) and rectum (50%) are more sensitive toward polyps and masses than the other three parts. Our research focused on detecting the colon by the individual diagnosis of sigmoid and rectum. We think it would make the rapid and easy diagnosis of colon in its earlier stage and help doctors for analysis of correct position of each part and detect the colon rectal cancer much easier.

The immediate effects of sigmoid colon manipulation on pressure pain thresholds in the lumbar spine.

PubMed

McSweeney, Terence P; Thomson, Oliver P; Johnston, Ross

2012-10-01

Visceral manual therapy is increasingly used by UK osteopaths and manual therapists, but there is a paucity of research investigating its underlying mechanisms, and in particular in relation to hypoalgesia. The aim of this study was to investigate the immediate effects of osteopathic visceral mobilisation on pressure pain thresholds. A single-blinded, randomised, within subjects, repeated measures design was conducted on 15 asymptomatic subjects. Pressure pain thresholds were measured at the L1 paraspinal musculature and 1st dorsal interossei before and after osteopathic visceral mobilisation of the sigmoid colon. The results demonstrated a statistically significant improvement in pressure pain thresholds immediately after the intervention (P<0.001). This effect was not observed to be systemic, affecting only the L1 paraspinal musculature. This novel study provides new experimental evidence that visceral manual therapy can produce immediate hypoalgesia in somatic structures segmentally related to the organ being mobilised, in asymptomatic subjects. Copyright © 2012. Published by Elsevier Ltd.

Peroral Endoscopic Myotomy for Treating Achalasia and Esophageal Motility Disorders

PubMed Central

Youn, Young Hoon; Minami, Hitomi; Chiu, Philip Wai Yan; Park, Hyojin

2016-01-01

Peroral endoscopic myotomy (POEM) is the application of esophageal myotomy to the concept of natural orifice transluminal surgery (NOTES) by utilizing a submucosal tunneling method. Since the first case of POEM was performed for treating achalasia in Japan in 2008, this procedure is being more widely used by many skillful endosopists all over the world. Currently, POEM is a spotlighted, emerging treatment option for achalasia, and the indications for POEM are expanding to include long-standing, sigmoid shaped esophagus in achalasia, even previously failed endoscopic treatment or surgical myotomy, and other spastic esophageal motility disorders. Accumulating data about POEM demonstrate excellent short-term outcomes with minimal risk of major adverse events, and some existing long-term data show the efficacy of POEM to be long lasting. In this review article, we review the technical details and clinical outcomes of POEM, and discuss some considerations of POEM in special situations. PMID:26717928

Seeking maximum linearity of transfer functions

NASA Astrophysics Data System (ADS)

Silva, Filipi N.; Comin, Cesar H.; Costa, Luciano da F.

2016-12-01

Linearity is an important and frequently sought property in electronics and instrumentation. Here, we report a method capable of, given a transfer function (theoretical or derived from some real system), identifying the respective most linear region of operation with a fixed width. This methodology, which is based on least squares regression and systematic consideration of all possible regions, has been illustrated with respect to both an analytical (sigmoid transfer function) and a simple situation involving experimental data of a low-power, one-stage class A transistor current amplifier. Such an approach, which has been addressed in terms of transfer functions derived from experimentally obtained characteristic surface, also yielded contributions such as the estimation of local constants of the device, as opposed to typically considered average values. The reported method and results pave the way to several further applications in other types of devices and systems, intelligent control operation, and other areas such as identifying regions of power law behavior.

López-Zepeda uterine manipulator: device description and its application in the total laparoscopic hysterectomy.

PubMed

López-Zepeda, M A; Morgan, F Ortiz; Reich, Harry

2010-04-01

During the total laparoscopic hysterectomy (TLH) operation, small changes in the uterine and vaginal cuff position, provided by an adequate manipulator, may optimize the attack angles to the vulnerable structures involved during the procedure and facilitate their dissection. The uterine manipulators are effective because they raise the uterus when moving it from one place to another, leaving the fixing elements on tension. The Lopez-Zepeda uterine manipulator exposes all the anatomic structures involved in TLH, especially those in the vulnerable areas. It avoids dissection and mobilization of the bladder and therefore its innervation. It takes the ureter away from the risky area by 4 cm. to 5 cm. decreasing the injury risk. Finally, thanks to its anteflexion and anteversion movement, it puts the posterior culdotomy area further away from the ureter, the rectum and the sigmoid colon.

Very short-term reactive forecasting of the solar ultraviolet index using an extreme learning machine integrated with the solar zenith angle.

PubMed

Deo, Ravinesh C; Downs, Nathan; Parisi, Alfio V; Adamowski, Jan F; Quilty, John M

2017-05-01

Exposure to erythemally-effective solar ultraviolet radiation (UVR) that contributes to malignant keratinocyte cancers and associated health-risk is best mitigated through innovative decision-support systems, with global solar UV index (UVI) forecast necessary to inform real-time sun-protection behaviour recommendations. It follows that the UVI forecasting models are useful tools for such decision-making. In this study, a model for computationally-efficient data-driven forecasting of diffuse and global very short-term reactive (VSTR) (10-min lead-time) UVI, enhanced by drawing on the solar zenith angle (θ s ) data, was developed using an extreme learning machine (ELM) algorithm. An ELM algorithm typically serves to address complex and ill-defined forecasting problems. UV spectroradiometer situated in Toowoomba, Australia measured daily cycles (0500-1700h) of UVI over the austral summer period. After trialling activations functions based on sine, hard limit, logarithmic and tangent sigmoid and triangular and radial basis networks for best results, an optimal ELM architecture utilising logarithmic sigmoid equation in hidden layer, with lagged combinations of θ s as the predictor data was developed. ELM's performance was evaluated using statistical metrics: correlation coefficient (r), Willmott's Index (WI), Nash-Sutcliffe efficiency coefficient (E NS ), root mean square error (RMSE), and mean absolute error (MAE) between observed and forecasted UVI. Using these metrics, the ELM model's performance was compared to that of existing methods: multivariate adaptive regression spline (MARS), M5 Model Tree, and a semi-empirical (Pro6UV) clear sky model. Based on RMSE and MAE values, the ELM model (0.255, 0.346, respectively) outperformed the MARS (0.310, 0.438) and M5 Model Tree (0.346, 0.466) models. Concurring with these metrics, the Willmott's Index for the ELM, MARS and M5 Model Tree models were 0.966, 0.942 and 0.934, respectively. About 57% of the ELM model's absolute errors were small in magnitude (±0.25), whereas the MARS and M5 Model Tree models generated 53% and 48% of such errors, respectively, indicating the latter models' errors to be distributed in larger magnitude error range. In terms of peak global UVI forecasting, with half the level of error, the ELM model outperformed MARS and M5 Model Tree. A comparison of the magnitude of hourly-cumulated errors of 10-min lead time forecasts for diffuse and global UVI highlighted ELM model's greater accuracy compared to MARS, M5 Model Tree or Pro6UV models. This confirmed the versatility of an ELM model drawing on θ s data for VSTR forecasting of UVI at near real-time horizon. When applied to the goal of enhancing expert systems, ELM-based accurate forecasts capable of reacting quickly to measured conditions can enhance real-time exposure advice for the public, mitigating the potential for solar UV-exposure-related disease. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

Field Programmable Gate Array (FPGA) Respiratory Monitoring System Using a Flow Microsensor and an Accelerometer

NASA Astrophysics Data System (ADS)

Mellal, Idir; Laghrouche, Mourad; Bui, Hung Tien

2017-04-01

This paper describes a non-invasive system for respiratory monitoring using a Micro Electro Mechanical Systems (MEMS) flow sensor and an IMU (Inertial Measurement Unit) accelerometer. The designed system is intended to be wearable and used in a hospital or at home to assist people with respiratory disorders. To ensure the accuracy of our system, we proposed a calibration method based on ANN (Artificial Neural Network) to compensate the temperature drift of the silicon flow sensor. The sigmoid activation functions used in the ANN model were computed with the CORDIC (COordinate Rotation DIgital Computer) algorithm. This algorithm was also used to estimate the tilt angle in body position. The design was implemented on reconfigurable platform FPGA.

Characteristics of polar coronal hole jets

NASA Astrophysics Data System (ADS)

Chandrashekhar, K.; Bemporad, A.; Banerjee, D.; Gupta, G. R.; Teriaca, L.

2014-01-01

Context. High spatial- and temporal-resolution images of coronal hole regions show a dynamical environment where mass flows and jets are frequently observed. These jets are believed to be important for the coronal heating and the acceleration of the fast solar wind. Aims: We studied the dynamics of two jets seen in a polar coronal hole with a combination of imaging from EIS and XRT onboard Hinode. We observed drift motions related to the evolution and formation of these small-scale jets, which we tried to model as well. Methods: Stack plots were used to find the drift and flow speeds of the jets. A toymodel was developed by assuming that the observed jet is generated by a sequence of single reconnection events where single unresolved blobs of plasma are ejected along open field lines, then expand and fall back along the same path, following a simple ballistic motion. Results: We found observational evidence that supports the idea that polar jets are very likely produced by multiple small-scale reconnections occurring at different times in different locations. These eject plasma blobs that flow up and down with a motion very similar to a simple ballistic motion. The associated drift speed of the first jet is estimated to be ≈27 km s-1. The average outward speed of the first jet is ≈171 km s-1, well below the escape speed, hence if simple ballistic motion is considered, the plasma will not escape the Sun. The second jet was observed in the south polar coronal hole with three XRT filters, namely, C-poly, Al-poly, and Al-mesh filters. Many small-scale (≈3″-5″) fast (≈200-300 km s-1) ejections of plasma were observed on the same day; they propagated outwards. We observed that the stronger jet drifted at all altitudes along the jet with the same drift speed of ≃7 km s-1. We also observed that the bright point associated with the first jet is a part of sigmoid structure. The time of appearance of the sigmoid and that of the ejection of plasma from the bright point suggest that the sigmoid is the progenitor of the jet. Conclusions: The enhancement in the light curves of low-temperature EIS lines in the later phase of the jet lifetime and the shape of the jet's stack plots suggests that the jet material falls back, and most likely cools down. To further support this conclusion, the observed drifts were interpreted within a scenario where reconnection progressively shifts along a magnetic structure, leading to the sequential appearance of jets of about the same size and physical characteristics. On this basis, we also propose a simple qualitative model that mimics the observations. Movies 1-3 are available in electronic form at http://www.aanda.org Warning, no authors found for 2014A&A...561A..97.

GaAs optoelectronic neuron arrays

NASA Technical Reports Server (NTRS)

Lin, Steven; Grot, Annette; Luo, Jiafu; Psaltis, Demetri

1993-01-01

A simple optoelectronic circuit integrated monolithically in GaAs to implement sigmoidal neuron responses is presented. The circuit integrates a light-emitting diode with one or two transistors and one or two photodetectors. The design considerations for building arrays with densities of up to 10,000/sq cm are discussed.

The trephine colostomy: a permanent left iliac fossa end colostomy without recourse to laparotomy.

PubMed Central

Senapati, A.; Phillips, R. K.

1991-01-01

An operative technique for performing a permanent end sigmoid colostomy without recourse to laparotomy is presented. The results from 16 patients have shown a very low morbidity. The technique was unsuccessful in three patients, each needing a formal laparotomy. PMID:1929133

Neural Networks Applied to Signal Processing

DTIC Science & Technology

1989-09-01

Distributed Processing, The MIT Press, Cambridge, MA, 1988. 3. Marvin Minsky and Seymour Papert, Perceptrons, The MIT Press, Cambridge, MA, 1969. 4...signum function, the linear function, and the sigmoid function. Initial research conducted in the 1950’s and 1960’s by Rosenblat, Minsky and others used

Extreme biology: probing life at low water contents and temperatures

USDA-ARS?s Scientific Manuscript database

Germplasm that is dried or cryopreserved appears quiescent. However, changes occur in preserved germplasm, albeit slowly. Viability time courses follow a sigmoidal curve where there is a lag phase when changes can’t be detected, followed by a period of rapid mortality. Predicting longevity under...

Numbers And Gains Of Neurons In Winner-Take-All Networks

NASA Technical Reports Server (NTRS)

Brown, Timothy X.

1993-01-01

Report presents theoretical study of gains required in neurons to implement winner-take-all electronic neural network of given size and related question of maximum size of winner-take-all network in which neurons have specified sigmoid transfer or response function with specified gain.

Image-Based 3D Treatment Planning for Vaginal Cylinder Brachytherapy: Dosimetric Effects of Bladder Filling on Organs at Risk

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hung, Jennifer; Shen Sui; De Los Santos, Jennifer F.

2012-07-01

Purpose: To investigate the dosimetric effects of bladder filling on organs at risk (OARs) using three-dimensional image-based treatment planning for vaginal cylinder brachytherapy. Methods and Materials: Twelve patients with endometrial or cervical cancer underwent postoperative high-dose rate vaginal cylinder brachytherapy. For three-dimensional planning, patients were simulated by computed tomography with an indwelling catheter in place (empty bladder) and with 180 mL of sterile water instilled into the bladder (full bladder). The bladder, rectum, sigmoid, and small bowel (OARs) were contoured, and a prescription dose was generated for 10 to 35 Gy in 2 to 5 fractions at the surface ormore » at 5 mm depth. For each OAR, the volume dose was defined by use of two different criteria: the minimum dose value in a 2.0-cc volume receiving the highest dose (D{sub 2cc}) and the dose received by 50% of the OAR volume (D{sub 50%}). International Commission on Radiation Units and Measurements (ICRU) bladder and rectum point doses were calculated for comparison. The cylinder-to-bowel distance was measured using the shortest distance from the cylinder apex to the contoured sigmoid or small bowel. Statistical analyses were performed with paired t tests. Results: Mean bladder and rectum D{sub 2cc} values were lower than their respective ICRU doses. However, differences between D{sub 2cc} and ICRU doses were small. Empty vs. full bladder did not significantly affect the mean cylinder-to-bowel distance (0.72 vs. 0.92 cm, p = 0.08). In contrast, bladder distention had appreciable effects on bladder and small bowel volume dosimetry. With a full bladder, the mean small bowel D{sub 2cc} significantly decreased from 677 to 408 cGy (p = 0.004); the mean bladder D{sub 2cc} did not increase significantly (1,179 cGy vs. 1,246 cGy, p = 0.11). Bladder distention decreased the mean D{sub 50%} for both the bladder (441 vs. 279 cGy, p = 0.001) and the small bowel (168 vs. 132 cGy, p = 0.001). Rectum and sigmoid volume doses were not affected by bladder filling. Conclusions: In high-dose rate vaginal cylinder brachytherapy, treatment with a distended bladder preferentially reduces high dose to the small bowel around the vaginal cuff without a significant change in dose to the bladder, rectum, or sigmoid.« less

Feasibility of therapeutic pneumoperitoneum in a large animal model using a microvaporisator.

PubMed

Reymond, M A; Hu, B; Garcia, A; Reck, T; Köckerling, F; Hess, J; Morel, P

2000-01-01

Multimodal therapy is used increasingly in advanced gastrointestinal tumors. Potential benefits of using an intraoperative adjuvant therapy during laparoscopy for cancer have been documented in animal studies. The aim of this study was to develop a device that could deliver such an intraoperative drug therapy. We developed a micropump suitable for minimally invasive surgery procedures that allowed microdroplets of therapeutic substance to be distributed into the pneumoperitoneum (CO2), creating a "therapeutic pneumoperitoneum." A closed-loop control system regulates drug delivery according to the gas flow. In vitro, the micropump is able to aerosolize various aqueous and ethanol solutions, including cytostatic and bacteriostatic drugs and adhesion-modulating agents. The size of the microdroplets has been optimized to prevent visual artifacts. The micropump was tested in an animal model (pig). The system was inserted into a 5-mm trocar. After insufflation of a 12-mm CO2 pneumoperitoneum, laparoscopic sigmoid colon resections could be performed with no special difficulties. No fog developed, and no system-related complication was observed. At autopsy, the active principle was distributed to all exposed peritoneal surfaces. As opposed to conventional peritoneal washing, therapeutic pneumoperitoneum reaches the entire peritoneal surface, allowing an optimal drug distribution. Drug diffusion into the tissues is enhanced by the intraperitoneal pressure. Precise determination of the instantaneous and total drug quantity is possible. Therefore, this drug delivery system has several advantages over conventional irrigation. Its potential domains of application are locoregional cancer therapy, prevention of port-site recurrences, immunomodulation, analgesia, peritonitis, and prevention of postoperative adhesions.

A Comparison of Cerebellar Retraction Pressures in Posterior Fossa Surgery: Extended Retrosigmoid Versus Traditional Retrosigmoid Approach.

PubMed

Liebelt, Brandon D; Huang, Meng; Britz, Gavin W

2018-05-01

The retrosigmoid approach is broadly applicable to many posterior fossa procedures. However, cerebellar retraction is often necessary for lesions in the cerebellopontine angle, which can lead to complications. An extended retrosigmoid approach skeletonizes the sigmoid sinus and allows a wider corridor with less retraction. This study investigated the differences in retraction pressure between the retrosigmoid and extended retrosigmoid approach in a cadaveric model. Anatomic dissection of 2 cadaveric heads was performed for comparison of surgical approaches. Bilateral measurements were obtained on each head, providing 4 sets of data. Retrosigmoid craniotomy was first performed with recording of retraction pressure necessary for 1.5-cm exposure. The exposure was then expanded to an extended retrosigmoid approach, and retraction pressures were recorded. Mean retraction pressure in cadaver 1 for retrosigmoid and extended retrosigmoid approaches was 20.25 ± 5.9 mm Hg and 10.25 ± 3.8 mm Hg, respectively; in cadaver 2, values were 11.75 ± 3.1 mm Hg and 4.75 ± 1.8 mm Hg, respectively. This corresponded to a mean relative reduction in retraction pressure of 49.4% in cadaver 1 and 59.6% in cadaver 2 by using the extended retrosigmoid approach. Retraction pressures were also significantly less (P < 0.05) for the extended retrosigmoid group when comparing all surgical approaches (N = 4). The extended retrosigmoid approach gains better visualization with reduced brain retraction. In our study, cerebellar retraction pressures were greatly reduced when using the extended retrosigmoid approach in a cadaveric model. Copyright © 2018. Published by Elsevier Inc.

Kinetics of the B1-B2 phase transition in KCl under rapid compression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Chuanlong; Smith, Jesse S.; Sinogeikin, Stanislav V.

2016-01-28

Kinetics of the B1-B2 phase transition in KCl has been investigated under various compression rates (0.03–13.5 GPa/s) in a dynamic diamond anvil cell using time-resolved x-ray diffraction and fast imaging. Our experimental data show that the volume fraction across the transition generally gives sigmoidal curves as a function of pressure during rapid compression. Based upon classical nucleation and growth theories (Johnson-Mehl-Avrami-Kolmogorov theories), we propose a model that is applicable for studying kinetics for the compression rates studied. The fit of the experimental volume fraction as a function of pressure provides information on effective activation energy and average activation volume at amore » given compression rate. The resulting parameters are successfully used for interpreting several experimental observables that are compression-rate dependent, such as the transition time, grain size, and over-pressurization. The effective activation energy (Q{sub eff}) is found to decrease linearly with the logarithm of compression rate. When Q{sub eff} is applied to the Arrhenius equation, this relationship can be used to interpret the experimentally observed linear relationship between the logarithm of the transition time and logarithm of the compression rates. The decrease of Q{sub eff} with increasing compression rate results in the decrease of the nucleation rate, which is qualitatively in agreement with the observed change of the grain size with compression rate. The observed over-pressurization is also well explained by the model when an exponential relationship between the average activation volume and the compression rate is assumed.« less

Rubber-like Quasi-thermosetting Polyetheramine-cured Epoxy Asphalt Composites Capable of Being Opened to Traffic Immediately

NASA Astrophysics Data System (ADS)

Kang, Yang; Wu, Qiang; Jin, Rui; Yu, Pengfei; Cheng, Jixiang

2016-01-01

This paper reports the facile preparation, mechanical performance and linear viscoelasticity of polyetheramine-cured rubber-like epoxy asphalt composites (EACs) with different asphalt contents. Compared with previous EACs prepared via complex chemical reactions and time-consuming high-temperature curing, the EACs reported here were obtained by using a compatible, bi-functional polyetheramine and a simple physical co-blend process, which make the EACs feasibly scalable for production at a lower cost. The EACs were cured for 1 h at 160 °C and 3 d at 60 °C therefore, these composites can be opened to traffic immediately. The EACs have a much greater temperature stability than common thermoplastic polymer-modified asphalt composites from -30 °C to 120 °C, but their complex shear moduli at higher temperatures slightly decrease instead of remaining constant when temperatures are greater than 80 °C, especially for the higher asphalt content composites; that is, these composites are quasi-thermosetting. Wicket plots illustrate that the EACs reported here are thermorheological simple materials, and the master curves are constructed and well-fitted by generalized logistic sigmoidal model functions. This research provides a facile, low-cost method for the preparation of polyetheramine-cured EACs that can be opened to traffic immediately, and the concept of quasi-thermosetting may facilitate the development of cheaper EACs for advanced applications.

Rubber-like Quasi-thermosetting Polyetheramine-cured Epoxy Asphalt Composites Capable of Being Opened to Traffic Immediately.

PubMed

Kang, Yang; Wu, Qiang; Jin, Rui; Yu, Pengfei; Cheng, Jixiang

2016-01-06

This paper reports the facile preparation, mechanical performance and linear viscoelasticity of polyetheramine-cured rubber-like epoxy asphalt composites (EACs) with different asphalt contents. Compared with previous EACs prepared via complex chemical reactions and time-consuming high-temperature curing, the EACs reported here were obtained by using a compatible, bi-functional polyetheramine and a simple physical co-blend process, which make the EACs feasibly scalable for production at a lower cost. The EACs were cured for 1 h at 160 °C and 3 d at 60 °C; therefore, these composites can be opened to traffic immediately. The EACs have a much greater temperature stability than common thermoplastic polymer-modified asphalt composites from -30 °C to 120 °C, but their complex shear moduli at higher temperatures slightly decrease instead of remaining constant when temperatures are greater than 80 °C, especially for the higher asphalt content composites; that is, these composites are quasi-thermosetting. Wicket plots illustrate that the EACs reported here are thermorheological simple materials, and the master curves are constructed and well-fitted by generalized logistic sigmoidal model functions. This research provides a facile, low-cost method for the preparation of polyetheramine-cured EACs that can be opened to traffic immediately, and the concept of quasi-thermosetting may facilitate the development of cheaper EACs for advanced applications.

Application of Artificial Neural Network to Predict Colour Change, Shrinkage and Texture of Osmotically Dehydrated Pumpkin

NASA Astrophysics Data System (ADS)

Tang, S. Y.; Lee, J. S.; Loh, S. P.; Tham, H. J.

2017-06-01

The objectives of this study were to use Artificial Neural Network (ANN) to predict colour change, shrinkage and texture of osmotically dehydrated pumpkin slices. The effects of process variables such as concentration of osmotic solution, immersion temperature and immersion time on the above mentioned physical properties were studied. The colour of the samples was measured using a colorimeter and the net colour difference changes, ΔE were determined. The texture was measured in terms of hardness by using a Texture Analyzer. As for the shrinkage, displacement of volume method was applied and percentage of shrinkage was obtained in terms of volume changes. A feed-forward backpropagation network with sigmoidal function was developed and best network configuration was chosen based on the highest correlation coefficients between the experimental values versus predicted values. As a comparison, Response Surface Methodology (RSM) statistical analysis was also employed. The performances of both RSM and ANN modelling were evaluated based on absolute average deviation (AAD), correlation of determination (R2) and root mean square error (RMSE). The results showed that ANN has higher prediction capability as compared to RSM. The relative importance of the variables on the physical properties were also determined by using connection weight approach in ANN. It was found that solution concentration showed the highest influence on all three physical properties.

H/C atomic ratio as a smart linkage between pyrolytic temperatures, aromatic clusters and sorption properties of biochars derived from diverse precursory materials

PubMed Central

Xiao, Xin; Chen, Zaiming; Chen, Baoliang

2016-01-01

Biochar is increasingly gaining attention due to multifunctional roles in soil amelioration, pollution mitigation and carbon sequestration. It is a significant challenge to compare the reported results from world-wide labs regarding the structure and sorption of biochars derived from various precursors under different pyrolytic conditions due to a lack of a simple linkage. By combining the published works on various biochars, we established a quantitative relationship between H/C atomic ratio and pyrolytic temperature (T), aromatic structure, and sorption properties for naphthalene and phenanthrene. A reverse sigmoid shape between T and the H/C ratio was observed, which was independent of the precursors of biochars, including the ash contents. Linear correlations of Freundlich parameters (N, log Kf) and sorption amount (log Qe, log QA) with H/C ratios were found. A rectangle-like model was proposed to predict the aromatic cluster sizes of biochars from their H/C ratios, and then a good structure-sorption relationship was derived. These quantitative relationships indicate that the H/C atomic ratio is a universal linkage to predict pyrolytic temperatures, aromatic cluster sizes, and sorption characteristics. This study would guide the global study of biochars toward being comparable, and then the development of the structure-sorption relationships will benefit the structural design and environmental application of biochars. PMID:26940984

Rubber-like Quasi-thermosetting Polyetheramine-cured Epoxy Asphalt Composites Capable of Being Opened to Traffic Immediately

PubMed Central

Kang, Yang; Wu, Qiang; Jin, Rui; Yu, Pengfei; Cheng, Jixiang

2016-01-01

This paper reports the facile preparation, mechanical performance and linear viscoelasticity of polyetheramine-cured rubber-like epoxy asphalt composites (EACs) with different asphalt contents. Compared with previous EACs prepared via complex chemical reactions and time-consuming high-temperature curing, the EACs reported here were obtained by using a compatible, bi-functional polyetheramine and a simple physical co-blend process, which make the EACs feasibly scalable for production at a lower cost. The EACs were cured for 1 h at 160 °C and 3 d at 60 °C; therefore, these composites can be opened to traffic immediately. The EACs have a much greater temperature stability than common thermoplastic polymer-modified asphalt composites from −30 °C to 120 °C, but their complex shear moduli at higher temperatures slightly decrease instead of remaining constant when temperatures are greater than 80 °C, especially for the higher asphalt content composites; that is, these composites are quasi-thermosetting. Wicket plots illustrate that the EACs reported here are thermorheological simple materials, and the master curves are constructed and well-fitted by generalized logistic sigmoidal model functions. This research provides a facile, low-cost method for the preparation of polyetheramine-cured EACs that can be opened to traffic immediately, and the concept of quasi-thermosetting may facilitate the development of cheaper EACs for advanced applications. PMID:26733315

Interaction of 17α-hydroxylase, 17(20)-lyase (CYP17A1) inhibitors - abiraterone and galeterone - with human sterol 14α-demethylase (CYP51A1).

PubMed

Masamrekh, Rami; Kuzikov, Alexey; Veselovsky, Alexander; Toropygin, Iliya; Shkel, Tatsiana; Strushkevich, Natalia; Gilep, Andrei; Usanov, Sergey; Archakov, Alexander; Shumyantseva, Victoria

2018-05-21

Abiraterone and galeterone induce type I differential spectral changes in human sterol 14α-demethylase (cytochrome P450 51A1, CYP51A1) with the sigmoidal shape of the binding curve. After approximation of the data by Hill model, the half-saturation concentrations (K 0.5 ) were estimated as 22 ± 1 μM and 16 ± 1 μM and the Hill coefficients as 2.4 ± 0.2 and 1.97 ± 0.23 for abiraterone and galeterone, respectively. We analyzed the catalytic activity of CYP51A1 towards abiraterone and galeterone using an electrochemical system based on recombinant CYP51A1 immobilized on the screen-printed graphite electrode (SPE) modified by didodecyldimethylammonium bromide (DDAB) film. The study revealed the amperometric response of CYP51A1 upon addition of abiraterone, which may indicate the substrate properties of abiraterone towards CYP51A1. Galeterone caused negligible amperometric response of CYP51A1. Mass-spectrometric analysis of the products of CYP51A1-dependent electrocatalytic reaction at a controlled potential towards abiraterone and galeterone revealed products with m/z of 366.3 and 405.2, respectively, indicating monohydroxylation of abiraterone and galeterone. We have observed the sigmoidal character of the dependence of the catalytic current on abiraterone concentration. Analysis of molecular docking data demonstrated the ability of abiraterone and galeterone to bind to the active site of CYP51A1, but abiraterone occupies the position closer to the heme. Copyright © 2018. Published by Elsevier Inc.

Quantifying intervertebral disc mechanics: a new definition of the neutral zone

PubMed Central

2011-01-01

Background The neutral zone (NZ) is the range over which a spinal motion segment (SMS) moves with minimal resistance. Clear as this may seem, the various methods to quantify NZ described in the literature depend on rather arbitrary criteria. Here we present a stricter, more objective definition. Methods To mathematically represent load-deflection of a SMS, the asymmetric curve was fitted by a summed sigmoid function. The first derivative of this curve represents the SMS compliance and the region with the highest compliance (minimal stiffness) is the NZ. To determine the boundaries of this region, the inflection points of compliance can be used as unique points. These are defined by the maximum and the minimum in the second derivative of the fitted curve, respectively. The merits of the model were investigated experimentally: eight porcine lumbar SMS's were bent in flexion-extension, before and after seven hours of axial compression. Results The summed sigmoid function provided an excellent fit to the measured data (r2 > 0.976). The NZ by the new definition was on average 2.4 (range 0.82-7.4) times the NZ as determined by the more commonly used angulation difference at zero loading. Interestingly, NZ consistently and significantly decreased after seven hours of axial compression when determined by the new definition. On the other hand, NZ increased when defined as angulation difference, probably reflecting the increase of hysteresis. The methods thus address different aspects of the load-deflection curve. Conclusions A strict mathematical definition of the NZ is proposed, based on the compliance of the SMS. This operational definition is objective, conceptually correct, and does not depend on arbitrarily chosen criteria. PMID:21299900

Tracking progress towards global drinking water and sanitation targets: A within and among country analysis.

PubMed

Fuller, James A; Goldstick, Jason; Bartram, Jamie; Eisenberg, Joseph N S

2016-01-15

Global access to safe drinking water and sanitation has improved dramatically during the Millennium Development Goal (MDG) period. However, there is substantial heterogeneity in progress between countries and inequality within countries. We assessed countries' temporal patterns in access to drinking water and sanitation using publicly available data. We then classified countries using non-linear modeling techniques as having one of the following trajectories: 100% coverage, linear growth, linear decline, no change, saturation, acceleration, deceleration, negative acceleration, or negative deceleration. We further assessed the degree to which temporal profiles follow a sigmoidal pattern and how these patterns might vary within a given country between rural and urban settings. Among countries with more than 10 data points, between 15% and 38% showed a non-linear trajectory, depending on the indicator. Overall, countries' progress followed a sigmoidal trend, but some countries are making better progress and some worse progress than would be expected. We highlight several countries that are not on track to meet the MDG for water or sanitation, but whose access is accelerating, suggesting better performance during the coming years. Conversely, we also highlight several countries that have made sufficient progress to meet the MDG target, but in which access is decelerating. Patterns were heterogeneous and non-linearity was common. Characterization of these heterogeneous patterns will help policy makers allocate resources more effectively. For example, policy makers can identify countries that could make use of additional resources or might be in need of additional institutional capacity development to properly manage resources; this will be essential to meet the forthcoming Sustainable Development Goals. Copyright © 2015 Elsevier B.V. All rights reserved.

3D Structures & dynamic of the solar corona: inputs from stereovision technics and joined Ground Based and Space Observations for the development of Space Weather

NASA Astrophysics Data System (ADS)

Portier-Fozzani, F.; Noens, J.-C.

In this presentation, I will present different techniques for 3D coronal structures reconstructions. Multiscale vision model (MVM, collaboration with A. Bijaoui) based on wavelet decomposition were used to prepare data. With SOHO/EIT, geometrical constraints were added to be able to measure by stereovision loop size parameters. Thus from these parameters, while including information of several observation wavelenghts, it has been possible by using the CHIANTI code to derive temperature and density along and across the loops, and thus to determine loops physical properties. During the emergence of a new active region, a more sophisticated method, was made to measure the twist degree variations. Loops appear twisted and detwist as expand. The magnetic helicity conservation gives thus important criteria to derive the limit of the stability for a non forced phenomena. Sigmoids, twisted ARLs, sheared filament are related with flares and CMEs. In that case 3D measurement can say upon which level of twist the structure will become unstable. With basic geometrical measures, it has been seen that a new active region reconnected a sigmoide leading to a flare. Also, for CMEs, the measure of the filament ejection angle from stereo EUV images, and the following of temporal evolution from coronagraphic measurement such as done by HACO at the Pic Du Midi Observatory, gives possibility to determine if the CME is coming toward the Earth, and when eventually would be the impact with the magnetosphere. The input of new missions such as STEREO/SECCHI would allow us to better understood the coronal dynamic. Such joined observations GBO-space, used simultaneously together with 3D methods, will allow to develop efficiently forecasting for Space Weather.

Damage control strategy for the treatment of perforated diverticulitis with generalized peritonitis.

PubMed

Sohn, M; Agha, A; Heitland, W; Gundling, F; Steiner, P; Iesalnieks, I

2016-08-01

The best surgical strategy for the management of perforated diverticulitis with generalized peritonitis of the sigmoid colon is not clearly defined. The aim of this retrospective cohort study was to evaluate the value of a damage control strategy. All patients who underwent emergency laparotomy for perforated diverticular disease of the sigmoid colon with generalized peritonitis between 2010 and 2015 were included. The damage control strategy (study group), included a two- stage procedure: limited resection of the diseased colonic segment, closure of proximal colon and distal stump, and application of an abdominal vacuum at the initial surgery followed by second-look laparotomy 24-48 h later At this point a choice was made between anastomosis and Hartmann's procedure. The control group consisted of patients receiving definitive reconstruction (anastomosis or Hartmann's procedure) at the initial operation. Thirty-seven patients were included in the study. Damage control strategy was applied in 19 patients and the control group consisted of 18 patients. Both groups were comparable in terms of demographics, severity of peritonitis, and comorbidities. The overall postoperative mortality was 11 % (n = 4). There were no statistically significant differences between both groups regarding postoperative morbidity and mortality; however, a significantly higher proportion of patients in the control group had a stoma after the initial hospital stay (83 vs. 47 %, p = 0.038). This difference was still significant after adjustment for sex, age, Mannheim Peritonitis Index, American Society of Anesthesiologists class and presence of septic shock at presentation. At the end of the follow-up period, 15 of 17 survivors in the study group and 13 of 16 survivors in the control group had their intestinal continuity restored (p = 0.66). Damage control strategy in patients with generalized peritonitis due to perforated diverticulitis leads to a significantly reduced stoma rate after the initial hospital stay without an increased risk of postoperative morbidity.

Revisiting a model of ontogenetic growth: estimating model parameters from theory and data.

PubMed

Moses, Melanie E; Hou, Chen; Woodruff, William H; West, Geoffrey B; Nekola, Jeffery C; Zuo, Wenyun; Brown, James H

2008-05-01

The ontogenetic growth model (OGM) of West et al. provides a general description of how metabolic energy is allocated between production of new biomass and maintenance of existing biomass during ontogeny. Here, we reexamine the OGM, make some minor modifications and corrections, and further evaluate its ability to account for empirical variation on rates of metabolism and biomass in vertebrates both during ontogeny and across species of varying adult body size. We show that the updated version of the model is internally consistent and is consistent with other predictions of metabolic scaling theory and empirical data. The OGM predicts not only the near universal sigmoidal form of growth curves but also the M(1/4) scaling of the characteristic times of ontogenetic stages in addition to the curvilinear decline in growth efficiency described by Brody. Additionally, the OGM relates the M(3/4) scaling across adults of different species to the scaling of metabolic rate across ontogeny within species. In providing a simple, quantitative description of how energy is allocated to growth, the OGM calls attention to unexplained variation, unanswered questions, and opportunities for future research.

Feedforward neural network model estimating pollutant removal process within mesophilic upflow anaerobic sludge blanket bioreactor treating industrial starch processing wastewater.

PubMed

Antwi, Philip; Li, Jianzheng; Meng, Jia; Deng, Kaiwen; Koblah Quashie, Frank; Li, Jiuling; Opoku Boadi, Portia

2018-06-01

In this a, three-layered feedforward-backpropagation artificial neural network (BPANN) model was developed and employed to evaluate COD removal an upflow anaerobic sludge blanket (UASB) reactor treating industrial starch processing wastewater. At the end of UASB operation, microbial community characterization revealed satisfactory composition of microbes whereas morphology depicted rod-shaped archaea. pH, COD, NH 4 + , VFA, OLR and biogas yield were selected by principal component analysis and used as input variables. Whilst tangent sigmoid function (tansig) and linear function (purelin) were assigned as activation functions at the hidden-layer and output-layer, respectively, optimum BPANN architecture was achieved with Levenberg-Marquardt algorithm (trainlm) after eleven training algorithms had been tested. Based on performance indicators such the mean squared errors, fractional variance, index of agreement and coefficient of determination (R 2 ), the BPANN model demonstrated significant performance with R 2 reaching 87%. The study revealed that, control and optimization of an anaerobic digestion process with BPANN model was feasible. Copyright © 2018 Elsevier Ltd. All rights reserved.

Diverticular Pylephlebitis and Polymicrobial Septicemia.

PubMed

Ram, Pradhum; Lapumnuaypol, Kamolyut; Punjabi, Chitra

2017-01-01

Diverticulitis primarily affects the sigmoid colon and is often complicated by intra-abdominal abscesses and fistulas. Rarely, however, mesenteric venous thrombosis has been known to occur. Optimal management is still unclear. We report the first case of polymicrobial sepsis resulting from diverticular pylephlebitis, managed successfully with bowel rest, antibiotics, and anticoagulation.

Sorption interactions of organic compounds with soils affected by agricultural olive mill wastewater.

PubMed

Keren, Yonatan; Borisover, Mikhail; Bukhanovsky, Nadezhda

2015-11-01

The organic compound-soil interactions may be strongly influenced by changes in soil organic matter (OM) which affects the environmental fate of multiple organic pollutants. The soil OM changes may be caused by land disposal of various OM-containing wastes. One unique type of OM-rich waste is olive mill-related wastewater (OMW) characterized by high levels of OM, the presence of fatty aliphatics and polyphenolic aromatics. The systematic data on effects of the land-applied OMW on organic compound-soil interactions is lacking. Therefore, aqueous sorption of simazine and diuron, two herbicides, was examined in batch experiments onto three soils, including untreated and OMW-affected samples. Typically, the organic compound-soil interactions increased following the prior land application of OMW. This increase is associated with the changes in sorption mechanisms and cannot be attributed solely to the increase in soil organic carbon content. A novel observation is that the OMW application changes the soil-sorbent matrix in such a way that the solute uptake may become cooperative or the existing ability of a soil sorbent to cooperatively sorb organic molecules from water may become characterized by a larger affinity. The remarkable finding of this study was that in some cases a cooperative uptake of organic molecules by soils makes itself evident in distinct sigmoidal sorption isotherms rarely observed in soil sorption of non-ionized organic compounds; the cooperative herbicide-soil interactions may be characterized by the Hill model coefficients. However, no single trend was found for the effect of applied OMW on the mechanisms of organic compound-soil interactions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Quantum Assisted Learning for Registration of MODIS Images

NASA Astrophysics Data System (ADS)

Pelissier, C.; Le Moigne, J.; Fekete, G.; Halem, M.

2017-12-01

The advent of the first large scale quantum annealer by D-Wave has led to an increased interest in quantum computing. However, the quantum annealing computer of the D-Wave is limited to either solving Quadratic Unconstrained Binary Optimization problems (QUBOs) or using the ground state sampling of an Ising system that can be produced by the D-Wave. These restrictions make it challenging to find algorithms to accelerate the computation of typical Earth Science applications. A major difficulty is that most applications have continuous real-valued parameters rather than binary. Here we present an exploratory study using the ground state sampling to train artificial neural networks (ANNs) to carry out image registration of MODIS images. The key idea to using the D-Wave to train networks is that the quantum chip behaves thermally like Boltzmann machines (BMs), and BMs are known to be successful at recognizing patterns in images. The ground state sampling of the D-Wave also depends on the dynamics of the adiabatic evolution and is subject to other non-thermal fluctuations, but the statistics are thought to be similar and ANNs tend to be robust under fluctuations. In light of this, the D-Wave ground state sampling is used to define a Boltzmann like generative model and is investigated to register MODIS images. Image intensities of MODIS images are transformed using a Discrete Cosine Transform and used to train a several layers network to learn how to align images to a reference image. The network layers consist of an initial sigmoid layer acting as a binary filter of the input followed by a strict binarization using Bernoulli sampling, and then fed into a Boltzmann machine. The output is then classified using a soft-max layer. Results are presented and discussed.

Analytical advantages of copolymeric microspheres for fluorimetric sensing - tuneable sensitivity sensors and titration agents.

PubMed

Stelmach, Emilia; Maksymiuk, Krzysztof; Michalska, Agata

2017-01-15

Analytical benefits related to application of copolymeric microspheres containing different number of carboxylic acid mers have been studied on example of acrylate copolymers. These structures can be used as a reagent in heterogeneous pH titration, benefiting from different number of reactive groups - i.e. different concentration of a titrant - within the series of copolymers. Thus introducing the same amount of different microspheres from a series to the sample, different amount of the titrant is introduced. Copolymeric microspheres also can be used as optical sensors - in this respect the increasing number of reactive groups in the series is useful to improve the analytical performance of microprobes - sensitivity of determination or/and response range. The increase in ion-permeability of the spheres with increasing number of reactive mers is advantageous. It is shown that for pH sensitive microspheres containing higher number of carboxyl groups the higher sensitivity for alkaline pH samples is observed for an indicator present in the beads. The significant increase of optical responses is related to enhanced ion transport within the microspheres. For zinc or potassium ions model sensors tested it was shown that by choice of pH conditions and type of microspheres from the series, the optical responses can be tuned - to enhance sensitivity for analyte concentration change as well as to change the response pattern from sigmoidal (higher sensitivity, narrow range) to linear (broader response range). For classical optode systems (e.g. microspheres containing an optical transducer - pH sensitive dye and optically silent ionophore - receptor) copolymeric microspheres containing carboxylic acid mers in their structure allow application of the sensor in alkaline pH range, which is usually inaccessible for applied optical transducer. Copyright © 2016 Elsevier B.V. All rights reserved.

Numerical solution of a logistic growth model for a population with Allee effect considering fuzzy initial values and fuzzy parameters

NASA Astrophysics Data System (ADS)

Amarti, Z.; Nurkholipah, N. S.; Anggriani, N.; Supriatna, A. K.

2018-03-01

Predicting the future of population number is among the important factors that affect the consideration in preparing a good management for the population. This has been done by various known method, one among them is by developing a mathematical model describing the growth of the population. The model usually takes form in a differential equation or a system of differential equations, depending on the complexity of the underlying properties of the population. The most widely used growth models currently are those having a sigmoid solution of time series, including the Verhulst logistic equation and the Gompertz equation. In this paper we consider the Allee effect of the Verhulst’s logistic population model. The Allee effect is a phenomenon in biology showing a high correlation between population size or density and the mean individual fitness of the population. The method used to derive the solution is the Runge-Kutta numerical scheme, since it is in general regarded as one among the good numerical scheme which is relatively easy to implement. Further exploration is done via the fuzzy theoretical approach to accommodate the impreciseness of the initial values and parameters in the model.

A FRAMEWORK FOR ATTRIBUTE-BASED COMMUNITY DETECTION WITH APPLICATIONS TO INTEGRATED FUNCTIONAL GENOMICS.

PubMed

Yu, Han; Hageman Blair, Rachael

2016-01-01

Understanding community structure in networks has received considerable attention in recent years. Detecting and leveraging community structure holds promise for understanding and potentially intervening with the spread of influence. Network features of this type have important implications in a number of research areas, including, marketing, social networks, and biology. However, an overwhelming majority of traditional approaches to community detection cannot readily incorporate information of node attributes. Integrating structural and attribute information is a major challenge. We propose a exible iterative method; inverse regularized Markov Clustering (irMCL), to network clustering via the manipulation of the transition probability matrix (aka stochastic flow) corresponding to a graph. Similar to traditional Markov Clustering, irMCL iterates between "expand" and "inflate" operations, which aim to strengthen the intra-cluster flow, while weakening the inter-cluster flow. Attribute information is directly incorporated into the iterative method through a sigmoid (logistic function) that naturally dampens attribute influence that is contradictory to the stochastic flow through the network. We demonstrate advantages and the exibility of our approach using simulations and real data. We highlight an application that integrates breast cancer gene expression data set and a functional network defined via KEGG pathways reveal significant modules for survival.

Inferring genetic interactions via a nonlinear model and an optimization algorithm.

PubMed

Chen, Chung-Ming; Lee, Chih; Chuang, Cheng-Long; Wang, Chia-Chang; Shieh, Grace S

2010-02-26

Biochemical pathways are gradually becoming recognized as central to complex human diseases and recently genetic/transcriptional interactions have been shown to be able to predict partial pathways. With the abundant information made available by microarray gene expression data (MGED), nonlinear modeling of these interactions is now feasible. Two of the latest advances in nonlinear modeling used sigmoid models to depict transcriptional interaction of a transcription factor (TF) for a target gene, but do not model cooperative or competitive interactions of several TFs for a target. An S-shape model and an optimization algorithm (GASA) were developed to infer genetic interactions/transcriptional regulation of several genes simultaneously using MGED. GASA consists of a genetic algorithm (GA) and a simulated annealing (SA) algorithm, which is enhanced by a steepest gradient descent algorithm to avoid being trapped in local minimum. Using simulated data with various degrees of noise, we studied how GASA with two model selection criteria and two search spaces performed. Furthermore, GASA was shown to outperform network component analysis, the time series network inference algorithm (TSNI), GA with regular GA (GAGA) and GA with regular SA. Two applications are demonstrated. First, GASA is applied to infer a subnetwork of human T-cell apoptosis. Several of the predicted interactions are supported by the literature. Second, GASA was applied to infer the transcriptional factors of 34 cell cycle regulated targets in S. cerevisiae, and GASA performed better than one of the latest advances in nonlinear modeling, GAGA and TSNI. Moreover, GASA is able to predict multiple transcription factors for certain targets, and these results coincide with experiments confirmed data in YEASTRACT. GASA is shown to infer both genetic interactions and transcriptional regulatory interactions well. In particular, GASA seems able to characterize the nonlinear mechanism of transcriptional regulatory interactions (TIs) in yeast, and may be applied to infer TIs in other organisms. The predicted genetic interactions of a subnetwork of human T-cell apoptosis coincide with existing partial pathways, suggesting the potential of GASA on inferring biochemical pathways.

A case of triple volvulus.

PubMed

Elsharif, M; Basu, I; Phillips, D

2012-03-01

Situs inversus is a rare congenital anomaly that has reportedly been associated with caecal volvulus. We describe a case of partial situs inversus complicated by intestinal obstruction secondary to three simultaneously occurring volvuli of the stomach, caecum and sigmoid colon. To our knowledge, this is the first documented case in the literature of multiple, simultaneously occurring volvuli.

Rigidity Sensing Explained by Active Matter Theory

PubMed Central

Marcq, Philippe; Yoshinaga, Natsuhiko; Prost, Jacques

2011-01-01

The magnitude of traction forces exerted by living animal cells on their environment is a monotonically increasing and approximately sigmoidal function of the stiffness of the external medium. We rationalize this observation using active matter theory, and propose that adaptation to substrate rigidity results from an interplay between passive elasticity and active contractility. PMID:21943439

Probing the biology of dry biological systems to address the basis of seed longevity

USDA-ARS?s Scientific Manuscript database

Drying cells reduces molecular mobility and slows chemical and physical reactions. As a result, dry biological systems deteriorate slowly. The time course of deterioration in a population of living cells often follows a sigmoidal pattern in which aging is occurring but no changes to viability are ...

Simulation of Homologous and Cannibalistic Coronal Mass Ejections produced by the Emergence of a Twisted Flux Rope into the Solar Corona

NASA Astrophysics Data System (ADS)

Chatterjee, Piyali; Fan, Yuhong

2013-11-01

We report the first results of a magnetohydrodynamic simulation of the development of a homologous sequence of three coronal mass ejections (CMEs) and demonstrate their so-called cannibalistic behavior. These CMEs originate from the repeated formations and partial eruptions of kink unstable flux ropes as a result of continued emergence of a twisted flux rope across the lower boundary into a pre-existing coronal potential arcade field. The simulation shows that a CME erupting into the open magnetic field created by a preceding CME has a higher speed. The second of the three successive CMEs is cannibalistic, catching up and merging with the first into a single fast CME before exiting the domain. All the CMEs including the leading merged CME, attained speeds of about 1000 km s-1 as they exit the domain. The reformation of a twisted flux rope after each CME eruption during the sustained flux emergence can naturally explain the X-ray observations of repeated reformations of sigmoids and "sigmoid-under-cusp" configurations at a low-coronal source of homologous CMEs.

Cystadenocarcinoma of the appendix: an incidental imaging finding in a patient with adenocarcinomas of the ascending and the sigmoid colon

PubMed Central

Pitiakoudis, Michail; Argyropoulou, Paraskevi I; Tsaroucha, Alexandra K; Prassopoulos, Panos; Simopoulos, Constantinos

2003-01-01

Background Primary adenocarcinomas of the appendix are uncommon. Mucoceles that result from mucinous adenocarcinomas of the appendix may be incidentally detected on imaging. Case presentation A case of a mucocele of the appendix, due to cystadenocarcinoma, is presented as an incidental imaging finding in a female, 86-year-old patient. The patient was admitted due to rectal hemorrhage and underwent colonoscopy, x-ray, US and CT. Adenocarcinoma of the ascending colon, adenomatous polyp of the sigmoid colon and a cystic lesion in the right iliac fossa were diagnosed. The cystic lesion was characterized as mucocele. The patient underwent right hemicolectomy, excision of the mucocele and sigmoidectomy. She recovered well and in two-year follow-up is free from cancer. Conclusions Preoperative diagnosis of an underlying malignancy in a mucocele is important for patient management, but it is difficult on imaging studies. Small lymph nodes or soft tissue stranding in the surrounding fat on computed tomography examination may suggest the possibility of malignancy. PMID:14572318

Cecal volvulus caused by endometriosis in a young woman.

PubMed

Ito, Daisuke; Kaneko, Susumu; Morita, Kouji; Seiichiro, Shimizu; Teruya, Masanori; Kaminishi, Michio

2015-06-24

Cecal volvulus is relatively rare. Moreover, to the best of our knowledge, a case of cecal volvulus caused by endometriosis has not yet been reported. A 41-year-old woman was admitted to our hospital with a 14-day history of subacute intermittent right lower quadrant abdominal pain. Simple abdominal radiography and abdominal computed tomography findings were suggestive of sigmoid volvulus, and she underwent an emergency colonoscopy. Following colonoscopic reduction, the patient's symptoms resolved quickly, and elective laparoscopic surgery was scheduled 2 weeks after admission. Intraoperative examination revealed a significantly distended cecum and ascending colon, which was twisted around a short rope-like adhesion that connected the cecum and the mesentery of the transverse colon, whereas the sigmoid colon was neither twisted nor extended. We laparoscopically performed an ileocecal resection. The postsurgery histopathological examination revealed the presence of endometrial tissue in the short rope-like adhesion. This finding confirmed that cecal volvulus in this patient was caused by endometriosis. Cecal volvulus should be considered in relatively young women who present with atypical right lower abdominal pain. Whenever possible, secondary factors should be evaluated preoperatively, especially in relatively young patients.

Analysis of the Tikhonov regularization to retrieve thermal conductivity depth-profiles from infrared thermography data

NASA Astrophysics Data System (ADS)

Apiñaniz, Estibaliz; Mendioroz, Arantza; Salazar, Agustín; Celorrio, Ricardo

2010-09-01

We analyze the ability of the Tikhonov regularization to retrieve different shapes of in-depth thermal conductivity profiles, usually encountered in hardened materials, from surface temperature data. Exponential, oscillating, and sigmoidal profiles are studied. By performing theoretical experiments with added white noises, the influence of the order of the Tikhonov functional and of the parameters that need to be tuned to carry out the inversion are investigated. The analysis shows that the Tikhonov regularization is very well suited to reconstruct smooth profiles but fails when the conductivity exhibits steep slopes. We check a natural alternative regularization, the total variation functional, which gives much better results for sigmoidal profiles. Accordingly, a strategy to deal with real data is proposed in which we introduce this total variation regularization. This regularization is applied to the inversion of real data corresponding to a case hardened AISI1018 steel plate, giving much better anticorrelation of the retrieved conductivity with microindentation test data than the Tikhonov regularization. The results suggest that this is a promising way to improve the reliability of local inversion methods.