Statistical mechanics of low-density parity-check codes

We review recent theoretical progress on the statistical mechanics of error correcting codes, focusing on low-density parity-check (LDPC) codes in general, and on Gallager and MacKay-Neal codes in particular. By exploiting the relation between LDPC codes and Ising spin systems with multispin interactions, one can carry out a statistical mechanics based analysis that determines the practical and theoretical limitations of various code constructions, corresponding to dynamical and thermodynamical transitions, respectively, as well as the behaviour of error-exponents averaged over the corresponding code ensemble as a function of channel noise. We also contrast the results obtained using methods of statistical mechanics with those derived in the information theory literature, and show how these methods can be generalized to include other channel types and related communication problems.

The co-ordination chemistry of tellurium and related selenium ligands

2-(2-pyridyl)phenyl(p-ethoxyphenyl)tellurium(II), (RR1Te) reacts with HgC12 at room temperature to give white HgCl2.RR1Te. On setting aside, or on warming the reaction mixture a yellow material, [R1HgCl.(RTeCl)2] is formed. Multinuclear NMR(125Te, 199Hg, 1H) and mass spectroscopy confirm the formulation, and confirm the ease of transfer of the p-ethoxyphenyl group (R1) between the metal centres. The crystal structure of the yellow material consists of two discrete RTeCl molecules together with a R1HgCl molecule. There is no dative bond formation between these species, hence the preferred description of the formation of an inclusion complex. The reaction of RR1Te with Copper(I) chloride in the cold gives an air sensitive yellow product Cu3Cl3(RR1Te)2(0.5CH3CN); under reflux in air changes to the green Cu2Cl(RR1Te)(0.5 EtOH). By contrast, the reaction of RR1Te with acetonitrile solution of Copper(II) salts under mild conditions affords the white materials CuCl(RR1Te) and CuBr(RR1Te)H2O. RR1Te reacts with PdCl2 and PtCl2 to give materials albeit not well defined, can be seen as intermediates to the synthesis of inorganic phase of the type M3XTe2XCl2X. Paramagnetism is associated with some of the palladium and platinum products. The 195Pt NMR measurement in DMSO establishes the presence of six platinum species, which are assigned to Pt(IV), Pt(III) or Pt(II). The reactions show that in the presence of PdCl2 or PtCl2 both R and R1 are very labile. The reaction of RHgCl(R= 2-(2-pyridyl)phenyl) with SeX4(X= Cl, Br) gives compounds which suggest that both Trans-metallation and redox processes are involved. By varying reaction conditions materials which appear to be intermediates in the trans-metallation process are isolated. Potentially bidentate tellurium ligands having molecular formula RTe(CH2)nTeR,Ln, (R= Ph,(t-Bu). C6H4, n = 5,10) are prepared. Palladium and Platinum complexes containing these ligands are prepared. Also complex Ph3SnC1L(L = p-EtO.C6H4) is prepared.

Growth curve of the lichen Rhizocarpon geographicum

Data on the growth curve of the lichen Rhizocarpon geographicum were obtained by measuring the radial growth rates (mm per 1.5 years) of 39 thalli from 2 to 65 mm in diameter growing in the same environment. An Aplin and Hill plot (r2 – r1 against ln r2 – ln r1) of the data and regression analyses suggested an initial phase of growth (up to a diameter of about 7 mm) in which the relative growth rate increased rapidly. This was followed by a phase in which the relative growth rate fell but the radial growth rate continued to rise (7 to 20 mm in diameter). Radial growth was then relatively constant until about 45 mm diameter and then declined. The Aplin and Hill model did not fit the data as a whole but may apply for a transient period in thalli between about 7 and 16 mm in diameter. The curve shows some similarities to that suggested by lichenometric studies but differs in showing a less steep decline in growth rate after the ‘great’ period.

Solvent induced NMR chemical shifts that arise from molecular encounters

Recently Homer and Percival have postulated that intermolecular van der Waals dispersion forces can be characterized by three mechanisms. The first arises via the mean square reaction field < R1; 2> due to the transient dipole of a particular solute molecule that is considered situated in a cavity surrounded by solvent molecules; this was characterized by an extended Onsager approach. The second stems from the extra cavity mean square reaction field < R2; 2> of the near neighbour solvent molecules. The third originates from square field electric fields E2BI due to a newly characterized effect in which solute atoms are `buffeted' by the peripheral atoms of adjacent solvent molecules. The present work concerns more detailed studies of the buffeting screening, which is governed by sterically controlled parameter (2T - T)2, where and are geometric structural parameters. The original approach is used to characterise the buffeting shifts induced by large solvent molecules and the approach is found to be inadequate. Consequently, improved methods of calculating and are reported. Using the improved approach it is shown that buffeting is dependent on the nature of the solvent as well as the nature of the solute molecule. Detailed investigation of the buffeting component of the van der Waals chemical shifts of selected solutes in a range of solvents containing either H or Cl as peripheral atoms have enabled the determination of a theoretical acceptable value for the classical screening coefficient B for protons. 1H and 13C resonance studies of tetraethylmethane and 1H, 13C and 29Si resonance studies of TMS have been used to support the original contention that three (< R1; 2> , < R2; 2> and E2BI) components of intermolecular van der Waals dispersion fields are required to characterise vdW chemical shifts.

Insulin release from cultured B-cells

Established RlNm5F and lN111 R1 and newly available HlT-T15 and UMR 407/3 B-cell lines have been successfully maintained in vitro. With the exclusion of UMR 407/3 cells, all lines were continuously propagable. Doubling times and plating efficiencies for HlT-T15, RlNm5F, lN111 R1 and UMR 407/3 cells were 20 hours and 85%, 31 hours and 76%, 24 hours and 80% and 38 hours and 94% respectively. All the cell lines were anchorage dependent, but only UMR 407/3 cells grew to confluence. Only HlT-T15 and UMR 407/3 cells produced a true insulin response to glucose but glucose markedly increased the rate of D-[U14C]glucose oxidation by all the cell lines. Glucose induced insulin release from HlT-T15 cells was biphasic with an exaggerated first phase. Insulin release from HlT-T15, RlNm5F and IN111 R1 cells was stimulated by amino acids and sulphonylureas. Glucagon stimulated insulin release from HlT-T15 and RlNm5F cells while somatostatin and pancreatic polypeptide inhibited release. These observations suggest that net insulin release from the whole islet may be the result of significant paracrine interaction. HlT-T15 and RlNm5F cell insulin release was stimulated by forskolin and inhibited by imidazole. Ca2+ channel blockade and calmodulin inhibition suppressed insulin release from HlT-T15, RlNm5F and IN111 R1 cells. In addition phorbol esters stimulated insulin release from RlNm5F cells. These data implicate cAMP, Ca2+ and protein kinase-C in the regulation of insulin release from cultured B-cells. Acetylcholine increased insulin release from HlT-T15 and RlNm5F cells. Inhibition of the response by atropine confirmed the involvement of muscarinic receptors. HlT-T15 cell insulin release was also inhibited by adrenaline. These observations suggest a possible role for the autonomic nervous system in the modulation of insulin release. Preliminary studies with a human insulinoma maintained in monolayer culture have demonstrated a limited life span of some seven weeks, a continuous low level of insulin release but no insulin response to glucose challenge.

Low thermal sensitivity grating devices based on ex-45° tilting structure capable of forward-propagating cladding modes coupling

The authors describe a detailed investigation on tilted fiber Bragg grating (TFBG) structures with tilted angles exceeding 45°. In contrast to the backward mode coupling mechanism of Bragg gratings with normal and small tilting structures, the ex-45° TFBGs facilitate the light coupling to the forward-propagating cladding modes. The authors have also theoretically and experimentally examined the mode coupling transition of TFBGs with small, medium, and large tilt angles. In particular, experiments are conducted to investigate the spectra and far-field distribution, as well as temperature, strain, and refractive-index sensitivities of ex-45° devices. It has been revealed that these ex-45° gratings exhibit ultralow thermal sensitivity. As in-fiber devices, they may be superior to conventional Bragg and long-period gratings when the low thermal cross sensitivity is required.

Grading and disease management in national screening for diabetic retinopathy in England and Wales

Aims - A National Screening Programme for diabetic eye disease in the UK is in development. We propose a grading and early disease management protocol to detect sight-threatening diabetic retinopathy and any retinopathy, which will allow precise quality assurance at all steps while minimizing false-positive referral to the hospital eye service. Methods - Expert panel structured discussions between 2000 and 2002 with review of existing evidence and grading classifications. Proposals - Principles of the protocol include: separate grading of retinopathy and maculopathy, minimum number of steps, compatible with central monitoring, expandable for established more complex systems and for research, no lesion counting, no ‘questionable’ lesions, attempt to detect focal exudative, diffuse and ischaemic maculopathy and fast track referral from primary or secondary graders. Sight-threatening diabetic retinopathy is defined as: preproliferative retinopathy or worse, sight-threatening maculopathy and/or the presence of photocoagulation. In the centrally reported minimum data set retinopathy is graded into four levels: none (R0), background (R1), preproliferative (R2), proliferative (R3). Maculopathy and photocoagulation are graded as absent (M0, P0) or present (M1, P1). Discussion - The protocol developed by the Diabetic Retinopathy Grading and Disease Management Working Party represents a new consensus upon which national guidelines can be based leading to the introduction of quality-assured screening for people with diabetes.

Comparative quantitative study of ‘signature’ pathological lesions in the hippocampus and adjacent gyri of 12 neurodegenerative disorders

The hippocampus (HC) and adjacent gyri are implicated in dementia in several neurodegenerative disorders. To compare HC pathology among disorders, densities of ‘signature’ pathological lesions were measured at a standard location in eight brain regions of 12 disorders. Principal components analysis of the data suggested that the disorders could be divided into three groups: (1) Alzheimer’s disease (AD), Down’s syndrome (DS), sporadic Creutzfeldt–Jakob disease, and variant Creutzfeldt–Jakob disease in which either β-amyloid (Aβ) or prion protein deposits were distributed in all sectors of the HC and adjacent gyri, with high densities being recorded in the parahippocampal gyrus and subiculum; (2) Pick’s disease, sporadic frontotemporal lobar degeneration with TDP-43 immunoreactive inclusions, and neuronal intermediate filament inclusion disease in which relatively high densities of neuronal cytoplasmic inclusions were present in the dentate gyrus (DG) granule cells; and (3) Parkinson’s disease dementia, dementia with Lewy bodies, progressive supranuclear palsy, corticobasal degeneration, and multiple system atrophy in which densities of signature lesions were relatively low. Variation in density of signature lesions in DG granule cells and CA1 were the most important sources of neuropathological variation among disorders. Hence, HC and adjacent gyri are differentially affected in dementia reflecting either variation in vulnerability of hippocampal neurons to specific molecular pathologies or in the spread of pathological proteins to the HC. Information regarding the distribution of pathology could ultimately help to explain variations in different cognitive domains, such as memory, observed in various disorders.

Influência da paridade, do tipo de parto e do nível de atividade física sobre a musculatura do assoalho pélvico em mulheres na pós-menopausa

The post-menopause stage is characterized by hormonal and organic alterations of ovarian failure. One of the most important of these is muscles alterations of the pelvic floor (MPF). According to current literature, in young women gynecological and obstetric factors, as well as lifestyles and habits influence that loss of function. However, there is still uncertainty about the influence of those variables in the MPF functions in post-menopause women. Thus, this study aimed at seeing if there is an influence from number of births, the type of birth and the level of physical activity on the MPF of post-menopause women. Another objective of this study was to compare MPF force in women who had had vaginal births with those who had been subjected to cesarean sections, those with different levels of physical activity and those with artificial and natural menopause in the initial and latter stages. Furthermore, the test of muscular force was compared to perineometry. Using observational, analytical and transversal observations, 100 women in the post-menopausal stage of life, between the ages of 45 and 65, were examined. They were divided according to the menopausal stage into three groups: women who had undergone hysterectomies, those in the initial stages of postmenopause and those in the late stage of postmenpause. The patients were questioned about social, demographic, gynecological and obstetric factors. All the volunteers were submitted to a physical examination where their height and weight were measured to arrive at the corporal mass index and their waist measurements were taken. The evaluation of the pelvic floor was conducted with muscular force tests and perineometry. These results were analyzed with statistical description and ANOVA statistical tests, multiple regression and Kolmogorov-Smirnov evaluations. The results showed homogeneity with regard to social demographic and anthropometric characteristics among the women in the final test sample (n=85). It was also seen that most of the women in all three groups were married (p=0.51) and catholic (p=0.13). The average per capital income varied between $R585.47 (+/-466.67) and $R1,271.83 (+/-1,748.95), with no significant difference between the groups (p=0.05). The G>6 group presented an average age between 58.95 (+/-3.96) which was significantly greater that the G<6 group´s average age (53.21+/- 3.88) (p=0.000). There was no difference between the groups´ anthropometric characteristics of weight (p=0.32), height (p=0.72) and corporal mass index (p=0.34), nor in the waist measurements (p=0.33). Furthermore, no significant difference was noted in the MPF function of women who had had normal births, cesarean sections or a combination of the two (TFM p=0.897; perineum measurement p=0.502). Likewise, no differences were seen in the MPF function of women who had one, two to three or four or more births (TFM p=0.28, perineum measurement p=0.13). Finally, no difference was perceived among those with different levels of physical activity (TFM p=0.663; perineum measurement p=0.741). Therefore, we found that the type of delivery, number of births and physical activity had no influence on the muscular function of the pelvic floor among the women studied. It is believed that decline in muscular function in post-menopause women is fundamentally related to the process of aging.

Conhecimento da doença renal crônica entre médicos conforme as diretrizes práticas

INTRODUCTION: Chronic kidney disease (CKD) is a global health problem, with increasing prevalence in its terminal stage and one of the factors that can contribute is the failure to recognize the disease and its risk factors. OBJECTIVE: To evaluate the knowledge of medical residents (MR) and medical preceptors (MP) in hospitals in the Federal University of Rio Grande do Norte in Natal-RN - Brazil, on the DRC, based on the policy of the Kidney Disease Improving Global Outcomes (KDIGO ). METHODS: Cross-sectional study where 64 MR (R1 = 32; R2 = 15; R3 = 17) and 63 MP answered a questionnaire divided into seven sessions that addressed aspects of the DRC since the setting up referral to a nephrologist. RESULTS: Only 20 participants (15.7%) reported using any guidelines for the management of CKD. The scores obtained by session were: Definition and classification (46.1 ± 47.8); Risk factors (70.5 ± 27.9); Laboratory evaluation (58.2 ± 8.8); Clinical action plan (57.6 ± 19.9); Reduction in proteinuria (68.3 ± 15.0); Complications (64.8 ± 19.9); Referral to a nephrologist (73.0 ± 44.6). There was a statistically significant difference between the knowledge of MR and MP in the sessions: Laboratory evaluation (MR 61.5 ± 8.4 vs 54.8 ± 7.9 MP; p <0.001); Reduction in proteinuria (73.1 ± 11.4 vs MR MP 63.5 ± 16.7; p <0.001) and Referral to a nephrologist (MR 81.2 ± 39.3 vs 64.5 ± 48.2 MP; p = 0.035). Among the MR, the R2 obtained the best score (63.9 ± 22.6 vs R1 R2 R3 71.9 ± 17.2 vs 63.5 ± 22.5, p = 0.445). It identified a low percentage of success of the doctors on the definition of CKD (MP = 46%; R1 = 40.6%; R2 = 60%; R3 = 52.9%; p = 0.623) and classification (MP = 34.9%; R1 = 53.1%, R2 = 60%; R3 = 52.9%; p = 0.158). CONCLUSION: The study showed that most doctors do not use any guidelines for clinical management of CKD and that there are gaps in knowledge on the subject, even among physicians who work in the university environment. In this sense, we propose the realization of mini-workshops for participants and students from boarding UFRN, using Case-Based Learning Strategy (CBL), with small group discussion, to strengthen the incorporation of CKD guidelines in undergraduate teaching and in clinical medical practice in general.

Conhecimento da doença renal crônica entre médicos conforme as diretrizes práticas

INTRODUCTION: Chronic kidney disease (CKD) is a global health problem, with increasing prevalence in its terminal stage and one of the factors that can contribute is the failure to recognize the disease and its risk factors. OBJECTIVE: To evaluate the knowledge of medical residents (MR) and medical preceptors (MP) in hospitals in the Federal University of Rio Grande do Norte in Natal-RN - Brazil, on the DRC, based on the policy of the Kidney Disease Improving Global Outcomes (KDIGO ). METHODS: Cross-sectional study where 64 MR (R1 = 32; R2 = 15; R3 = 17) and 63 MP answered a questionnaire divided into seven sessions that addressed aspects of the DRC since the setting up referral to a nephrologist. RESULTS: Only 20 participants (15.7%) reported using any guidelines for the management of CKD. The scores obtained by session were: Definition and classification (46.1 ± 47.8); Risk factors (70.5 ± 27.9); Laboratory evaluation (58.2 ± 8.8); Clinical action plan (57.6 ± 19.9); Reduction in proteinuria (68.3 ± 15.0); Complications (64.8 ± 19.9); Referral to a nephrologist (73.0 ± 44.6). There was a statistically significant difference between the knowledge of MR and MP in the sessions: Laboratory evaluation (MR 61.5 ± 8.4 vs 54.8 ± 7.9 MP; p <0.001); Reduction in proteinuria (73.1 ± 11.4 vs MR MP 63.5 ± 16.7; p <0.001) and Referral to a nephrologist (MR 81.2 ± 39.3 vs 64.5 ± 48.2 MP; p = 0.035). Among the MR, the R2 obtained the best score (63.9 ± 22.6 vs R1 R2 R3 71.9 ± 17.2 vs 63.5 ± 22.5, p = 0.445). It identified a low percentage of success of the doctors on the definition of CKD (MP = 46%; R1 = 40.6%; R2 = 60%; R3 = 52.9%; p = 0.623) and classification (MP = 34.9%; R1 = 53.1%, R2 = 60%; R3 = 52.9%; p = 0.158). CONCLUSION: The study showed that most doctors do not use any guidelines for clinical management of CKD and that there are gaps in knowledge on the subject, even among physicians who work in the university environment. In this sense, we propose the realization of mini-workshops for participants and students from boarding UFRN, using Case-Based Learning Strategy (CBL), with small group discussion, to strengthen the incorporation of CKD guidelines in undergraduate teaching and in clinical medical practice in general.

Receptores de citocinas proinflamatórias na pré-eclâmpsia

Preeclampsia is a disease specific of human pregnancy that affects 3-8% of pregnant women, and it is one of the three leading causes of maternal mortality and morbidity. The disease is characterized by hypertension and proteinuria after the 20th week of gestation. The risk factors for this disease are not completely understood but appear to include dysregulation of the immune response arising from defects in placentation, environmental and genetic factors. This study aimed to determine whether the variation in the amount of proinflammatory cytokine receptors IL-1R2, IL-6R and TNF-αR1 would be involved in preeclampsia. They were recruited women with preeclampsia (n=24) and women who evolved during pregnancy without changes in blood pressure (n=12) were recruited. Clinical and laboratory data were collected. The cytokine receptors (IL-1R2, TNF-αR1 and IL-6R) were assessed in mononuclear cells isolated from peripheral blood using flow cytometry (Control = 8; PE = 24). C-reactive protein (CRP) was determined by CRP ultrasensitive method (Control = 7; PE = 18) was performed using sera pregnant women. Women with preeclampsia had higher weight at the beginning of the pregnancy (p=0.0171) and lower gestational age at delivery (0.0008). Classical monocytes were decreased in preeclampsia but not intermediate or non-classical monocytes. The frequency of IL-1R2 pro inflammatory cytokine receptors is decreased in women with PE only in the subpopulation of non-classical monocytes (p = 0.0011). TNF-αR1 receptor and IL-6R, had a decreased frequency in the three subpopulations of monocyte (classic, intermediate and non-classical) when compared to women with normal pregnancy. An increase in IL-1R2 receptor in TCD4+ lymphocytes, but a decrease in TNF-receptor and IL-6R in women with preeclampsia were found. No differences in the frequency of those receptors in CD3+/CD8+ in preeclampsia. There was no difference in C-reactive protein in preeclampsia. The reduction in the amount of IL-1R2, TNF- αR1 and IL-6R monocytes and lymphocytes can be involved in the regulation of inflammation observed in preeclampsia, contributing to disease.

T1 mapping for assessment of myocardial injury and microvascular obstruction at one week post myocardial infarction

Acknowledgements This study was supported by a Medical Research Council UK grant (grant number G0800901), as a sub-study of Nitrites in Acute Myocardial Infarction. Thanks are due to Roger Staff, for invaluable advice regarding receiver operator characteristic analysis.

T1 mapping for assessment of myocardial injury and microvascular obstruction at one week post myocardial infarction

Acknowledgements This study was supported by a Medical Research Council UK grant (grant number G0800901), as a sub-study of Nitrites in Acute Myocardial Infarction. Thanks are due to Roger Staff, for invaluable advice regarding receiver operator characteristic analysis.

Breads Fortified with Freeze-Dried Vegetables : Quality and Nutritional Attributes. Part II: Breads Not Containing Oil as an Ingredient

Acknowledgments: Funds for the study were provided by the Scottish Government's Rural and Environment Science and Analytical Services Division and conducted as part of the Scottish Government Strategic Research programme (Diet and Health Theme of the Food Land & People Programme). The authors are grateful to Phillip Morrice, Vivian Buchan, and Donna Henderson for helping with the nutritional analysis of the breads. The authors declare no conflicts of interest.