Beam Voltage Effects in the Study of Embedded Biological Materials by Secondary Electron Detectors

Thin and semithin sections were extensively examined by the secondary electron (SE) detector in a conventional scanning electron microscope (SEM), and in a transmission electron microscope with a scanning attachment (STEM). Various para-meters, in particular the beam voltage, were shown to affect the final SE image (SEI). As for SEM observation, a surface contrast was imaged at low primary electron (PE) voltages (0.6-2 kV), whereas a subsurface contrast predominated at higher energies (15-30 kV). In STEM, significant differences were not detected by varying the PE in the 20-100 kV range. Surface and subsurface in-formation was simultaneously imaged even though the SEI were better resolved at the highest energy

Molecular markers of weight loss in sleeve gastrectomy patients: A prospective cohort study

Background: Obesity is a polymorphic chronic disease that has reached epidemic proportions. Bariatric surgery including sleeve gastrectomy (SG) has an increasingly important role in long-term management of these patients. The molecular mechanisms post SG are complex and not fully understood. Aims: The primary study aim is to investigate the hormonal mechanisms by which SG effects weight loss and related health benefits by examining the association between SG weight loss and biochemical/hormone levels. A secondary aim was to assess the improvements in obesity related chronic disease states following SG. Methods: We conducted a prospective cohort study of obese patients undergoing SG and 2:1 age and sex matched non obese controls undergoing non- bariatric procedures during the study period from a single bariatric surgeon in Sydney. Height, weight, body mass index (BMI) and percentage excess body weight (%EBW) were determined for each subject at baseline, 3 and 6 months post SG. Plasma samples were obtained and key biochemical markers measured (NEFA (non-essential fatty acids), C-peptide, Ghrelin, GIP (Gastric Inhibitory Peptide), Glucagon Like Peptide -1 (GLP-1), insulin, resistin, visfatin, glucagon, leptin, Plasminogen Activator Inhibitor-1 (PAI-1)). Comparisons of baseline levels between obese and non obese subjects; and pre and post surgery levels and clinical factors in the SG cohort at 0, 3, 6 months post SG were performed using unpaired and paired t-tests respectively on Graph-Pad PRISM © software Results: 16 SG patients and 32 controls were included with 3 month clinical follow up available for all SG subjects and 3 month biochemical follow-up available for 11 SG subjects. In the SG cohort, the mean BMI at baseline was 43.5 +/- 1.8 kg/m2 SEM. Males undergoing SG were heavier than females. The mean %EBW loss was 42.3% +/- 8.4SD at 3 months and 51.5% +/- 18.5SD at 6 months. There was a statistically significant incremental weight loss between 3 and 6 month time points from baseline, p \u3c 0.0001 and p \u3c 0.0009 respectively. A statistically significant decrease in levels of NEFA, ghrelin, GLP-1, glucagon, leptin and PAI-1 was observed between baseline and 3 months post-operative (p \u3c 0.05). This reduction remained statistically significant at 6 months for NEFA and ghrelin. Due to small numbers at 6 months it is unclear if there are further changes in these hormone levels compared to 3 months. No statistically significant difference was found for C-peptide, GIP, insulin or resistin between baseline and 3 months. Mean visfatin and resistin levels differed between subjects and controls at baseline (time 0). There was no difference in mean baseline BMI and %EBW lost for the patients who completed clinical and biochemical follow up versus those who had clinical follow-up alone. In the SG cohort, secondary co-morbidities improved, with patients less dependent on oral hypoglycaemic agents for T2DM and improvements in hypertension, gastro-esophageal reflux disease and obstructive sleep apnea. Conclusions: We demonstrate significant weight loss and hormone changes post SG surgery. Our research adds to the literature to identify markers that are associated with surgical weight loss that may provide insights into the endocrine mechanisms or effects of surgical weight loss

Generalized Tsirelson Inequalities, Commuting-Operator Provers, and Multi-Prover Interactive Proof Systems

A central question in quantum information theory and computational complexity is how powerful nonlocal strategies are in cooperative games with imperfect information, such as multi-prover interactive proof systems. This paper develops a new method for proving limits of nonlocal strategies that make use of prior entanglement among players (or, provers, in the terminology of multi-prover interactive proofs). Instead of proving the limits for usual isolated provers who initially share entanglement, this paper proves the limits for "commuting-operator provers", who share private space, but can apply only such operators that are commutative with any operator applied by other provers. Commuting-operator provers are at least as powerful as usual isolated but prior-entangled provers, and thus, limits for commuting-operator provers immediately give limits for usual entangled provers. Using this method, we obtain an n-party generalization of the Tsirelson bound for the Clauser-Horne- Shimony-Holt inequality for every n. Our bounds are tight in the sense that, in every n-party case, the equality is achievable by a usual nonlocal strategy with prior entanglement. We also apply our method to a 3-prover 1-round binary interactive proof for NEXP. Combined with the technique developed by Kempe, Kobayashi, Matsumoto, Toner and Vidick to analyze the soundness of the proof system, it is proved to be NP-hard to distinguish whether the entangled value of a 3-prover 1-round binary-answer game is equal to 1 or at most 1-1/p(n) for some polynomial p, where n is the number of questions. This is in contrast to the 2-prover 1-round binary-answer case, where the corresponding problem is efficiently decidable. Alternatively, NEXP has a 3-prover 1-round binary interactive proof system with perfect completeness and soundness 1-2^{-poly}.Comment: 20 pages. v2: An incorrect statement in the abstract about the two-party case is corrected. Relation between this work and a preliminary work by Sun, Yao and Preda is clarifie

Imaging of mandibular fractures: a pictorial review

Mandibular fractures are among the most common maxillofacial fractures observed in emergency rooms and are mainly caused by road accidents. The clinical features of mandibular fractures include malocclusion and loss of mandibular function. Panoramic radiography is usually limited to isolated lesions, whereas computed tomography is the tool of choice for all other facial traumatic events. No reference standard classification system for the different types of mandibular fractures is defined. Therapeutic options include a conservative approach or surgical treatment based on the anatomic area and the severity of fracture. The main purpose of this pictorial review is to illustrate a practical description of the pathophysiology of mandibular fractures and describe both the imaging techniques to recognise them and the therapeutic indications

Formal framework for reasoning about the precision of dynamic analysis

Dynamic program analysis is extremely successful both in code debugging and in malicious code attacks. Fuzzing, concolic, and monkey testing are instances of the more general problem of analysing programs by dynamically executing their code with selected inputs. While static program analysis has a beautiful and well established theoretical foundation in abstract interpretation, dynamic analysis still lacks such a foundation. In this paper, we introduce a formal model for understanding the notion of precision in dynamic program analysis. It is known that in sound-by-construction static program analysis the precision amounts to completeness. In dynamic analysis, which is inherently unsound, precision boils down to a notion of coverage of execution traces with respect to what the observer (attacker or debugger) can effectively observe about the computation. We introduce a topological characterisation of the notion of coverage relatively to a given (fixed) observation for dynamic program analysis and we show how this coverage can be changed by semantic preserving code transformations. Once again, as well as in the case of static program analysis and abstract interpretation, also for dynamic analysis we can morph the precision of the analysis by transforming the code. In this context, we validate our model on well established code obfuscation and watermarking techniques. We confirm the efficiency of existing methods for preventing control-flow-graph extraction and data exploit by dynamic analysis, including a validation of the potency of fully homomorphic data encodings in code obfuscation