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In this paper, a new approach for fixed‐structure H2 controller design in terms of solutions to a set of linear matrix inequalities are given. Both discrete‐time and continuous‐time SISO time‐invariant systems are considered. Then the results are extended to systems with polytopic uncertainty. The presented methods are based on an inner convex approximation of the non‐convex set of fixed‐structure H2 controllers. The designed procedures are initialized either with a stable polynomial or with a stabilizing controller. An iterative procedure for robust controller design is given that converges to a suboptimal solution. The monotonic decreasing of the upper bound on the H2 norm is established theoretically for both nominal and robust controller design. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
84.
Alireza Tavassoli Reza Bagheri Behzad Feizzadeh Fatemeh Tavassoli Neusha Barekati 《The Indian journal of surgery》2015,77(2):245-247
Port site hernias are one of the most serious complications associated with laparoscopic surgery. In this study, we present a simple and reliable method for port site closure in laparoscopic surgery. From 2005 to 2011, 500 patients who underwent laparoscopic surgery were enrolled for the study. They were evaluated considering age, sex, indication of laparoscopic surgery, and early and late complications of port site and were followed up at least for 1 year after the surgery. In our study, 180 males and 320 females with mean age of 36 years were enrolled. The most common indication for laparoscopic surgery was cholecystectomy in 320 patients (64 %). There were no early or late complications of port site after surgery. Our method is a new modification of the procedure presented by Spalding. Using Allis forceps and putting it under the fascia seems to be a more suitable technique which facilitates the laparoscopic port repair. We found it to be extremely safe, simple, and easy to teach. 相似文献
85.
Maryam Khazdouz Majid Sezavar Bahareh Imani Hossein Akhavan Alireza Babapour Gholamreza Khademi 《African Journal of Paediatric Surgery》2015,12(2):143-147
Background:
Bowel function has been reported to be adversely affected following surgery in cases of Hirschsprung. We retrospectively studied both the clinical outcome and bowel function status following surgery in patients diagnosed with Hirschprung''s disease (HD). 161 cases, who underwent pull-through operations for HD in Sheikh Pediatric Tertiary Centre, Mashhad, Iran. The specified time bracket spanned between 2006 and 2011.Materials and Methods:
Data was extracted from Health Information System with the aim of investigating patients for both short and long-term gastrointestinal (GI) complications after surgery bases in addition to the concurrence of any associated anomalies. Three main procedures were analysed in this respect (Swenson, Duhamel and Soave).Results:
In a study of 96 (59%) boys and 65 (40.3%) girls, mortality rate was reported to be 15.5% (15 males and 10 females). A considerable majority of almost three fourths were detected with both early and late GI complications after surgery. The latter mainly included constipation (30.8%), incontinence (19.8%), enterocolitis (8%), diarrhea (11%) in a declining order of incidence. Down syndrome and others HD-associated anomalies were detected in 3.7% and 24.3% of cases respectively.Conclusions:
Constipation and foecal incontinence were the most prevalent postoperative complications, which were reported almost as frequent in other studies. Yet, Enterocolitis, was reported slightly less in prevalence. Also mortality rates were considerably higher, compared to developed nations.Key words: Bowel function, constipation, foecal incontinence, Hirschsprung''s disease 相似文献86.
Jad Salman Cayla A. Stifler Alireza Shahsafi Chang-Yu Sun Stephen C. Weibel Michel Frising Bryan E. Rubio-Perez Yuzhe Xiao Christopher Draves Raymond A. Wambold Zhaoning Yu Daniel C. Bradley Gabor Kemeny Pupa U. P. A. Gilbert Mikhail A. Kats 《Proceedings of the National Academy of Sciences of the United States of America》2021,118(15)
Structural characterization of biologically formed materials is essential for understanding biological phenomena and their enviro-nment, and for generating new bio-inspired engineering concepts. For example, nacre—the inner lining of some mollusk shells—encodes local environmental conditions throughout its formation and has exceptional strength due to its nanoscale brick-and-mortar structure. This layered structure, comprising alternating transparent aragonite (CaCO3) tablets and thinner organic polymer layers, also results in stunning interference colors. Existing methods of structural characterization of nacre rely on some form of cross-sectional analysis, such as scanning or transmission electron microscopy or polarization-dependent imaging contrast (PIC) mapping. However, these techniques are destructive and too time- and resource-intensive to analyze large sample areas. Here, we present an all-optical, rapid, and nondestructive imaging technique—hyperspectral interference tomography (HIT)—to spatially map the structural parameters of nacre and other disordered layered materials. We combined hyperspectral imaging with optical-interference modeling to infer the mean tablet thickness and its disorder in nacre across entire mollusk shells from red and rainbow abalone (Haliotis rufescens and Haliotis iris) at various stages of development. We observed that in red abalone, unexpectedly, nacre tablet thickness decreases with age of the mollusk, despite roughly similar appearance of nacre at all ages and positions in the shell. Our rapid, inexpensive, and nondestructive method can be readily applied to in-field studies.Complex optical phenomena can emerge from a variety of biological or bio-inspired processes, from arrays of colors in peacocks (1) and other birds (2), butterflies (3), and opals (4), to the metal-like sheen of herring (5) and unique polarization-dependent properties of jewel beetles (6) and Pollia fruit (7). Nacre, or mother-of-pearl, is a prominent biologically formed mineral structure found throughout our oceans. It lines the inside of the shells formed by many mollusks, including bivalves, cephalopods, and gastropods. It features brilliant iridescent colors (Fig. 1) and is studied and emulated in part because of its outstanding mechanical performance (8, 9). The striking, colorful appearance of nacre has been a source of scientific curiosity since the days of Brewster (10), Rayleigh (11), and Raman (12, 13), and is the product of optical interference resulting from multiple interface reflections as light propagates through its stratified structure comprising stacks of transparent polygonal aragonite tablets (CaCO3) interspersed with organic polymer (chitin and proteins) layers (14–16) (Fig. 1A). Nacre is one of seven mollusk shell structures (17). In the nacre structure, the aragonite tablets are typically 5 to 10 μm in diameter and hundreds of nanometers thick [200 to 1,100 nm across all shells, and 250 to 500 nm in red abalone (18)], while the organic sheets are an order of magnitude thinner (14, 16, 19). In columnar nacre formed by gastropods like abalone and snails (Fig. 1), co-oriented tablets are stacked on top of one another, while in sheet nacre formed by bivalves like pearl oysters and pen shells, co-oriented tablets are staggered diagonally (18) (see Movie S1 for an animation showing how co-oriented tablets are stacked in columnar nacre). Despite the significant structural and formation–mechanism differences, the thicknesses of tablets and organic layers are similar in columnar and sheet nacre, and so are the optical and mechanical behavior (20). The resulting palette of colors is primarily dependent on the nacre tablet thickness and the viewing angle, and the optical response that yields these colors can be understood as that of a Bragg reflector (21) with disorder in the layer thicknesses, where the optical band gaps are determined by the thicknesses of the transparent layers (5, 22, 23). Thus, the spectrum of light reflected from a nacre surface encodes information about its physical structure (Fig. 1 B–D).Open in a separate windowFig. 1.(A) Nacre, the colorful iridescent inner lining of some mollusk shells. Here, the red abalone, or H. rufescens, shell features columnar nacre, which comprises thousands of layers of polygonal aragonite tablets interspersed with organic sheets. (B) A close-up photograph of the nacre surface shows a variety of colors and nonuniformities. (C and D) Given a broadband white light source illuminating nacre at a fixed angle of incidence, variations in color are observed due to the difference in average thickness of aragonite tablets comprising nacre. (E) Hyperspectral interference tomography (HIT) setup: A hyperspectral camera collects predominantly specular reflectance data across a sample illuminated by a collimated source at a fixed angle of incidence from the normal to the sample . The reflected light is polarized using a wire-grid polarizer. (F) A color photograph of a region of nacre that was analyzed. (G) Map of the mean tablet thickness (MTT) obtained using HIT, overlaid on a grayscale rendering of the photograph in F. Highlighted in red is a 5 × 5-mm region used to analyze the ontogeny of nacre in Fig. 4. The region around this area was masked off using opaque tape, which is highlighted with the dashed white box.Understanding and characterizing the structure of nacre and other biomaterials have deep and surprising implications. For example, the average thickness of the tablets comprising ancient nacre can be used as a proxy for local ocean temperatures at the time of nacre formation, enabling paleoclimatology spanning hundreds of millions of years (18, 24, 25). The structure of nacre is also an inspiration for engineered materials thousands of times stronger than the constituent materials (15, 26, 27). To that end, new techniques have been developed to probe and understand the structure of nacre, such as polarization-dependent imaging contrast (PIC) mapping using X-ray absorption near-edge structure spectroscopy combined with photoemission electron spectromicroscopy (18, 28, 29), or X-ray nanotomography (30). However, these characterization techniques such as cross-sectional electron microscopy result in the destruction of the sample and are time-consuming and costly.Here, we present a method for rapid, nondestructive, and large-scale structural characterization of disordered and nonuniform stratified thin-film materials and apply it to the analysis of nacre. Our all-optical method employs hyperspectral imaging combined with thin-film modeling to extract nacre mean tablet thicknesses (MTTs) and tablet degree of disorder —defined as the standard deviation of the thicknesses—across large areas (Fig. 1 E–G). This characterization method is designated as hyperspectral interference tomography (HIT). We used HIT to map the structure of mollusk shell nacre across many stages of development and identified a previously unexplored relationship between the age of the organism and the structure of the nacre layer. We investigated two particular species of nacre-forming mollusks, Haliotis rufescens (red abalone) and Haliotis iris (paua, or rainbow abalone; data only in SI Appendix), for which the aragonite tablet thicknesses lie within a range of 250 to 500 nm (18, 31); however, the method is applicable to any other transparent layered structure of animal, plant, geologic, or synthetic origin. 相似文献
87.
88.
Safety,efficacy and pitfalls of fibrocyte application in the treatment of diabetic foot ulcer
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Mohaddeseh Behjati Mohammad Hashemi Alireza Shoarayenejati Khadijeh Karbalaie Mohammad H Nasr‐Esfahani 《International wound journal》2015,12(1):27-31
Fibrocytes are unique bone marrow‐derived cells with great potential in wound healing. Hence, the aim of this study was to determine the safety and efficacy of the applied circulating fibrocytes in the treatment of non healing diabetic foot ulcers. Peripheral blood mononuclear cells were isolated by centrifugation through Ficoll–Paque method. After 3 days, the non adherent cells were removed by a single, gentle aspiration. Adherent cells were cultured in the same medium for 10 days. The cells were characterised using mouse anti‐human‐CD45‐fluorescein isothiocyanate (FITC) and mouse anti‐human–collagen I, and also characterised by immunofluorescence microscopy using the above mentioned antibodies. Sterility measures were applied for clinical evaluation. Based on the literature review, cell transplantation generally requires at least 3 × 106 cells regarding efficacy measures. As fibrocytes are non proliferating cells, 350 ml patient's blood is required to prepare patient‐specific serum before cell isolation and culture, and 85 ml patient's blood is needed for cell isolation and differentiation on cell transplantation applications. In our survey, no diabetic patient was inclined to be donor of such blood volume, mainly because of their pre‐assumption that they are anaemic. It is concluded that fibrocytes do not seem to be candidate cells for cell therapy in the treatment of diabetic foot ulcers because of the rarity of this cell population in circulation. 相似文献
89.
Sarraf-Zadegan N Sadri G Malek Afzali H Baghaei M Mohammadi Fard N Shahrokhi S Tolooie H Poormoghaddas M Sadeghi M Tavassoli A Rafiei M Kelishadi R Rabiei K Bashardoost N Boshtam M Asgary S Naderi G Changiz T Yousefie A 《Acta cardiologica》2003,58(4):309-320
The Isfahan Healthy Heart Programme (IHHP) is a five to six year comprehensive integrated community-based programme for cardiovascular diseases (CVD) prevention and control via reducing CVD risk factors and improvement of cardiovascular healthy behaviour in a target population. IHHP started late in 1999 and will be finished in 2005-2006. A primary survey was done to collect baseline data from interventional (Isfahan and Najaf-Abad) and reference (Arak) communities. In a two-stage sampling method, we randomly selected 5 to 10 percent of households from randomly selected clusters. Then individuals aged > or = 19 years were selected for the survey. This way, data from 12,600 individuals (6300 in interventional counties and 6300 in the reference county) was collected and stratified according to living area (urban vs. rural) and different age and sex groups. The samples underwent a 30-minute interview to complete validated questionnaires containing questions on demography, socioeconomic status, smoking behaviour, physical activity, nutritional habits and other behaviour regarding CVD. Blood pressure and body mass index (BMI) measurements were done and fasting blood samples were taken for two hours post load plasma glucose (2 hpp), serum (total, HDL and LDL) cholesterol and triglyceride levels. A twelve-lead electrocardiogram was recorded in all persons above 35 years of age. Community-wide surveillance of deaths, hospital discharges, myocardial infarction and stroke registry was carried out in the intervention and control areas. Four to five years of interventions based on different categories such as mass media, community partnerships, health system involvement and policy and legislation have started in the intervention area while Arak will be followed without intervention. Considering the results of the baseline surveys, (assessments needed, the objectives, existing resources and the possibility of national implementation) the interventions were planned. They were set based on specific target groups like school children, women, work-site, health personnel, high-risk persons, and community leaders were actively engaged as decision makers. A series of teams was arranged for planning and implementation of the intervention strategies. Monitoring will be done on small samples to assess the effect of different interventions in the intervention area. While four periodic surveys will be conducted on independent samples to assess health behaviours related to CVD risk factors in the intervention and reference areas, the original pre-intervention subjects aged more than 35 years will be followed in both areas to assess the individual effect of interventions and outcomes like sudden death, fatal and nonfatal MI and stroke. The whole baseline survey will be repeated on the original and an independent sample in both communities at the end of the study. 相似文献
90.
Karimi M Hadi Imanieh M Ghiam AF Hashemi Z 《European journal of gastroenterology & hepatology》2005,17(12):1363-1367
BACKGROUND: Recurrent abdominal pain (RAP) affects many children, especially those affected by beta-thalassaemia major. The role of Helicobacter pylori is still unclear in children with RAP. OBJECTIVES: The aim of the present study was the comparison of beta-thalassaemia major patients and normal controls with RAP in H. pylori infection. The factors influencing H. pylori prevalence were also investigated. METHODS: A series of 50 beta-thalassaemia major cases (30 female, 20 male; aged 6-25 years) and 50 age-matched and sex-matched controls, both presenting with RAP, were recruited during a period of 18 months. The study participants were obtained through a multistage random sampling method among those that met Apley's criteria. All the patients and controls had undergone diagnostic oesophagogastroduodenoscopy with biopsy. H. pylori infection was confirmed by two histopathological examinations on an endoscopy sample and a rapid urease test. RESULTS: H. pylori infection in thalassaemic patients was more common than in controls [34/50 (68%) versus 30/50 (60%)], but this higher frequency was not statistically significant. A clear relationship was found between the prevalence of H. pylori and age, duration of transfusion/chelation programmes, pain duration and splenectomy. In contrast, H. pylori did not correlate with abdominal pain characteristics, blood group, serum ferritin level and pathology of the upper gastrointestinal tract. The most frequent endoscopy abnormality was gastritis (72%). Nausea and heartburn were the leading associated symptoms. CONCLUSION: The high prevalence of H. pylori infection suggests that H. pylori should be remembered as a probable cause of RAP in beta-thalassaemia major patients. 相似文献