323 research outputs found

    Aspects of moduli stabilization in type IIB string theory

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    We review moduli stabilization in type IIB string theory compactification with fluxes. We focus on the KKLT and Large Volume Scenario (LVS). We show that the predicted soft SUSY breaking terms in KKLT model are not phenomenological viable. In LVS, the following result for scalar mass, gaugino mass, and trilinear term is obtained: m0=m1/2=A0=m3/2m_0 =m_{1/2}= - A_0=m_{3/2}, which may account for Higgs mass limit if m3/2O(1.5)m_{3/2} \sim {\cal O}(1.5) TeV. However, in this case the relic abundance of the lightest neutralino can not be consistent with the measured limits. We also study the cosmological consequences of moduli stabilization in both models. In particular, the associated inflation models such as racetrack inflation and K\"ahler inflation are analyzed. Finally the problem of moduli destabilization and the effect of string moduli backreaction on the inflation models are discussed.Comment: 34 pages, 8 figure

    The Relationships Between Cervical Vertebral Maturation And Dental Calcification Among Malays [RK521. N265 2008 f rb ].

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    Kajian kematangan skeletal adalah penting dalam rawatan ortodontik. Kaedah permatangan vertebra servikal terbukti sebagai satu kaedah yang efektif dalam membuat penilaian pemecutan pertumbuhan remaja bagi setiap pesakit. Research on skeletal maturation is essential in orthodontics management.The cervical vertebral maturation method has proved to be effective in assessing the adolescent growth spurt in individual patients

    One session laparoscopic management of Mirizzi syndrome: feasible and safe in specialist units

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    BACKGROUND:To evaluate the laparoscopic management of Mirizzi syndrome, seldom diagnosed preoperatively causing difficulty when performing cholecystectomy and increasing complication risks. METHODS:Analysis of a prospective single-surgeon database of 5700 laparoscopic cholecystectomies found 58 Mirizzi syndrome cases. They were managed with an intention to treat during the index admission according to protocol of single-session management of bile duct stones. RESULTS:38/58 patients were females (65.5%). The median age was 55 years. 53 cases were emergency admissions. 34 cases (58.6%) only had ultrasound scanning. Operative difficulty was Grade IV in 34 cases (58.6%) and Grade V in 20 (34.5%) (Nassar Scale). There were 33 Mirizzi Type IA, 7 Type IB, 16 Type II and one each of Type III and Type IV. Bile duct exploration was performed in 94.8% through choledochotomy/ transfistula in 58.6% or transcystic in 36.2%. Four cases required conversion to open. Postoperative morbidity occurred in 29%. Two 30-day mortalities occurred from pneumonia in two elderly patients who were late referrals. CONCLUSION:Although the utilization of the laparoscopic approach in managing bile duct stones is not currently widely practiced it was safer in this series than in reported series of open surgery in Mirizzi Syndrome. The optimal approach to Mirizzi Type II is via cholecystocholedochal fistula to explore the bile duct then drain with T-tube through the fistula. It is unnecessary to perform bilioenteric bypass in majority of cases, reducing the morbidity and mortality

    Security in Wireless Sensor Networks - Improving the LEAP Protocol

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    Wireless sensor networks are becoming significantly vital to many applications, and they were initially used by the military for surveillance purposes. One of the biggest concerns of WSNs is that they are very defenceless to security threats. Due to the fact that these networks are susceptible to hackers; it is possible for one to enter and render a network. For example, such networks may be hacked into in the military, using the system to attack friendly forces. Leap protocol offers many security benefits to WSNs. However, with much research it became apparent that LEAP only employs one base station and always assumes that it is trustworthy. It does not consist of defence against hacked or compromised base stations. In this paper, intensive research was undertaken on LEAP protocols, finding out its security drawbacks and limitations. A solution has been proposed in order to overcome the security issues faced in implementing this protocol whilst employing more than one base station. The performance of the proposed solution has been evaluated and simulated to provide a better network performance

    Virtual Wireless and Mobile Communication Laboratory

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    Creating a virtual laboratory for distance learning courses has become recently so important recently for engineering education. In this paper, we provide a full description for a remote access technique used in a wireless and mobile communication laboratory. Hence, the student will be able to perform experiments online and controlling and watching the devices by accessing a camera already built in the laboratory. Signal generator, spectrum analyzer and field-fox devices are used in the virtual laboratory.https://doi.org/10.5923/j.edu.20120201.0

    Decision-making in pediatric persistent Mullerian duct syndrome

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    We are reporting a case of an 18-month old male who presented with bilateral cryptorchidism. The patient underwent an explorative laparoscopy in which two gonads were identified in close proximity to the uterus and fallopian tubes. Biopsy of the gonads confirmed testicular tissue. Genetic analysis demonstrated a 46, XY male. Male external genitalia were appropriate for age with no evidence of female structures. Persistent Mullerian duct syndrome is extremely rare, with approximately 260 cases reported in the literature. Best practice for the extent of surgical management is still evolving as we gather data on long-term outcomeKeywords: cryptorchidism, Mullerian duct syndrome, male pseudohermaphroditism, undescended testicl

    The effects of previous abdominal surgery and the utilisation of modified access techniques on the operative difficulty and outcomes of laparoscopic cholecystectomy and bile duct exploration

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    Background: Early reports suggested that previous abdominal surgery was a relative contraindication to laparoscopic cholecystectomy (LC) on account of difficulty and potential access complications. This study analyses different types/systems of previous surgery and locations of scars and how they affect access difficulties. As modified access techniques to minimise risk of complications are under-reported the study details and evaluates them. Method: Prospectively collected data from consecutive LC and common bile duct explorations (LCBDE) performed by a single surgeon over 30 years was analysed. Previous abdominal surgery was documented and peri-operative outcomes were compared with patients who had no previous surgery using Chi-squared analysis. Results: Of 5916 LC and LCBDE, 1846 patients (31.2%) had previous abdominal surgery. The median age was 60 years. Those with previous surgery required more frequent duodenal (RR 1.07; p = 0.023), hepatic flexure (RR 1.11; p = 0.043) and distal adhesiolysis (RR 3.57; p < 0.001) and had more access related bowel injuries (0.4% vs. 0.0%; p < 0.001). Previous upper gastrointestinal and biliary surgery had the highest rates of adhesiolysis (76.3%), difficult cystic pedicles (58.8%), fundus-first approach (7.2%), difficulty grades (64.9% Grades 3–5) and utilisation of abdominal drains (71.1%). Previous open surgery resulted in longer operative time compared to previous laparoscopic procedures (65vs.55 min; p < 0.001), increased difficulty of pedicle dissection (42.4% vs. 36.0%; p < 0.05) and required more duodenal, hepatic flexure and distant adhesiolysis (p < 0.05) and fundus-first dissection (4% vs 2%; p < 0.05). Epigastric and supraumbilical access and access through umbilical and other hernias were used in 163 patients (8.8%) with no bowel complications. Conclusion: The risks of access and adhesiolysis in patients with previous abdominal scars undergoing biliary surgery are dependent on the nature of previous surgery. Previous open, upper gastrointestinal and biliary surgery carried the most significant risks. Modified access techniques can be adopted to safely mitigate these risks

    Risk identification and technical modifications reduce the incidence of post-cholecystectomy bile leakage: analysis of 5675 laparoscopic cholecystectomies

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    Purpose: The main sources of post-cholecystectomy bile leakage (PCBL) not involving major duct injuries are the cystic duct and subvesical/hepatocystic ducts. Of the many studies on the diagnosis and management of PCBL, few addressed measures to avoid this serious complication. The aim of this study was to examine the causes and mechanisms leading to PCBL and to evaluate the effects of specific preventative strategies. Methods: A prospectively maintained database of 5675 consecutive laparoscopic cholecystectomies was analysed. Risk factors for post-cholecystectomy bile leakage were identified and documented and technical modifications and strategies were adopted to prevent this complication. The incidence, causes and management of patients who suffered bile leaks were studied and their preoperative characteristics, operative data and postoperative outcomes were compared with patients where potential risks were identified and PCBL avoided and with the rest of the series. Results: Twenty-five patients (0.4%) had PCBL (7 expected and less than half requiring reintervention): 11 from cystic ducts (0.2%), 3 from subvesical ducts (0.05%) and 11 from unconfirmed sources (0.2%). The incidence of cystic duct leakage was significantly lower with ties (0.15%) than with clips (0.7%). Fifty-two percent had difficulty grades IV or V, 36% had empyema or acute cholecystitis and 16% had contracted gallbladders. Twelve patients required 17 reinterventions before PCBL resolved; 7 percutaneous drainage, 6 ERCP and 4 relaparoscopy. The median hospital stay was 17 days with no mortality. Hepatocystic ducts were encountered in 72 patients (1.3%) and were secured with loops (54.2%), ties (25%) or sutures (20.8%) with no PCBL. Eighteen sectoral ducts were identified and secured. Conclusion: Ligation of the cystic duct reduces the incidence of PCBL resulting from dislodged endoclips. Careful blunt dissection in the proper anatomical planes avoiding direct or thermal injury to subvesical and sectoral ducts and a policy of actively searching for hepatocystic ducts during gallbladder separation to identify and secure them can reduce bile leakage from such ducts
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