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1.
Arch Womens Ment Health ; 27(2): 201-218, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-37989799

RESUMEN

Floods are increasing in frequency and may increase the risk for experiencing emotional distress, anxiety, depression and PTSD. The aim of this study was to determine the extent of damage, loss, injury and death resulting from floods that occurred in and around the city of Durban, South Africa, in April 2022, and associated changes in mental health pre- to post-floods in a low-income setting. Seventy-three women between the ages of 18 and 45, residing in flood affected, low-income settings, were interviewed prior to the floods occurring. Mental health measures were repeated with 69 of the 73 women during the post-flood interview along with a questionnaire measuring flood-related exposures. Loss of infrastructure (lacked access to drinking water, electricity, fresh food, could not travel to work, had to stay in a shelter and could not get hold of friends or family) was a predictor of post-flood change in levels of emotional distress and anxiety. Higher levels of prior trauma exposure were associated with higher post-flood levels of emotional distress. Higher pre-flood food insecurity was also associated with higher post-flood anxiety. Women affected by poverty, food insecurity and a history of trauma are vulnerable to the additive adverse mental health effects of floods. Proactive approaches to diminishing the impact of floods on the livelihood of women is needed and post-flood relieve efforts may be more affective if they are enhanced by providing mental health support.


Asunto(s)
Distrés Psicológico , Trastornos por Estrés Postraumático , Humanos , Femenino , Adolescente , Adulto Joven , Adulto , Persona de Mediana Edad , Inundaciones , Trastornos por Estrés Postraumático/epidemiología , Trastornos por Estrés Postraumático/psicología , Depresión/epidemiología , Sudáfrica/epidemiología , Ansiedad/epidemiología , Pobreza
2.
BMC Public Health ; 22(1): 1029, 2022 05 21.
Artículo en Inglés | MEDLINE | ID: mdl-35597933

RESUMEN

BACKGROUND: Evidence on the impact of COVID-19 and lockdown remains at an early stage. There is limited research about the impact of hard lockdown restrictions on families, specifically how these restrictions impact on women and children's experiences of domestic violence, including intimate partner violence (IPV) and child abuse in South Africa. We conducted research among men and women in Gauteng province, South Africa to understand their experiences of the COVID-19 national lockdown and its impact and link to women and children's experiences of domestic violence. METHODS: We conducted a qualitative study, using social media to recruit men and women who were 18 years and older, living with a spouse and/or children in Gauteng province, South Africa during the lockdown. To collect the data, we conducted telephone interviews, and analyzed data using the thematic approach. RESULTS: The lockdown had unprecedented negative economic impacts on families, and exacerbated some of the risk factors for violence against women and children in the home in South Africa. Some women reported experiences of emotional violence. Experiences of physical violence were mostly amongst children. The risk factors for women and children's experiences of violence in the home differed by socio-economic class. Job losses and reduction in earnings resulted to food insecurity which was a key driver of violence in most low socio-economic status (SES) families. Confinement in the home with spouses was an unfamiliar and difficult experience, associated with conflict and perpetration of violence by men in high SES families. Participants across socio-economic groups reported high levels of stress with limited psychosocial support available during the lockdown. CONCLUSIONS: Our finding showing a link between low-socio-economic status and increased risk for domestic violence during the lockdown in South Africa suggests the need for socio-economic interventions to mitigate these risks. Structural and social relief measures need to be strengthened to reduce the loss of jobs and income and to address food insecurity during pandemics. Psychosocial support should be provided to men and women to mitigate the mental health impacts of the pandemics and lockdown.


Asunto(s)
COVID-19 , Violencia de Pareja , COVID-19/epidemiología , COVID-19/prevención & control , Niño , Control de Enfermedades Transmisibles , Femenino , Humanos , Violencia de Pareja/psicología , Masculino , Pandemias/prevención & control , Sudáfrica/epidemiología
3.
Phys Rev Lett ; 120(7): 076602, 2018 Feb 16.
Artículo en Inglés | MEDLINE | ID: mdl-29542933

RESUMEN

We report the results of a combined study of the normal-state resistivity and superconducting transition temperature T_{c} of the unconventional superconductor Sr_{2}RuO_{4} under uniaxial pressure. There is strong evidence that, as well as driving T_{c} through a maximum at ∼3.5 K, compressive strains ϵ of nearly 1% along the crystallographic [100] axis drive the γ Fermi surface sheet through a van Hove singularity, changing the temperature dependence of the resistivity from T^{2} above, and below the transition region to T^{1.5} within it. This occurs in extremely pure single-crystals in which the impurity contribution to the resistivity is <100 nΩ cm, so our study also highlights the potential of uniaxial pressure as a more general probe of this class of physics in clean systems.

4.
Nutr Metab Cardiovasc Dis ; 27(2): 138-146, 2017 02.
Artículo en Inglés | MEDLINE | ID: mdl-28089080

RESUMEN

BACKGROUND AND AIM: Preliminary findings indicate that consumption of Salba-chia (Salvia hispanica L.), an ancient seed, improves management of type 2 diabetes and suppresses appetite. The aim of this study was to assesse the effect of Salba-chia on body weight, visceral obesity and obesity-related risk factors in overweight and obese adults with type 2 diabetes. METHODS: A double-blind, randomized, controlled trial with two parallel groups involved 77 overweight or obese patients with type 2 diabetes (HbA1c: 6.5-8.0%; BMI: 25-40 kg/m2). Both groups followed a 6-month calorie-restricted diet; one group received 30 g/1000 kcal/day of Salba-chia, the other 36 g/1000 kcal/day of an oat bran-based control. Primary endpoint was change in body weight over 6-months. Secondary endpoints included changes in waist circumference, body composition, glycemic control, C-reactive protein, and obesity-related satiety hormones. RESULTS: At 6-months, participants on Salba-chia had lost more weight than those on control (1.9 ± 0.5 kg and 0.3 ± 0.4 kg, respectively; P = 0.020), accompanied by a greater reduction in waist circumference (3.5 ± 0.7 cm and 1.1 ± 0.7 cm, respectively; P = 0.027). C-reactive protein was reduced by 1.1 ± 0.5 mg/L (39 ± 17%) on Salba-chia, compared to 0.2 ± 0.4 mg/L (7 ± 20%) on control (P = 0.045). Plasma adiponectin on the test intervention increased by 6.5 ± 0.7%, with no change observed on control (P = 0.022). CONCLUSIONS: The results of this study, support the beneficial role of Salba-chia seeds in promoting weight loss and improvements of obesity related risk factors, while maintaining good glycemic control. Supplementation of Salba-chia may be a useful dietary addition to conventional therapy in the management of obesity in diabetes. REGISTRATION: clinicaltrials.gov identifier: NCT01403571.


Asunto(s)
Restricción Calórica , Diabetes Mellitus Tipo 2/complicaciones , Dieta Reductora , Obesidad/dietoterapia , Salvia , Semillas , Pérdida de Peso , Adiposidad , Diabetes Mellitus Tipo 2/diagnóstico , Método Doble Ciego , Femenino , Humanos , Masculino , Persona de Mediana Edad , Obesidad/complicaciones , Obesidad/diagnóstico , Obesidad/fisiopatología , Ontario , Fitoterapia , Plantas Medicinales , Factores de Tiempo , Resultado del Tratamiento
5.
Phys Rev Lett ; 116(19): 197003, 2016 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-27232037

RESUMEN

Here we demonstrate how the Fermi surface topology and quantum many-body interactions can be manipulated via epitaxial strain in the spin-triplet superconductor Sr_{2}RuO_{4} and its isoelectronic counterpart Ba_{2}RuO_{4} using oxide molecular beam epitaxy, in situ angle-resolved photoemission spectroscopy, and transport measurements. Near the topological transition of the γ Fermi surface sheet, we observe clear signatures of critical fluctuations, while the quasiparticle mass enhancement is found to increase rapidly and monotonically with increasing Ru-O bond distance. Our work demonstrates the possibilities for using epitaxial strain as a disorder-free means of manipulating emergent properties, many-body interactions, and potentially the superconductivity in correlated materials.

6.
J Evol Biol ; 28(2): 368-75, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25495081

RESUMEN

For ectotherms, environmental temperatures influence numerous life history characteristics, and the body temperatures (Tb ) selected by individuals can affect offspring fitness and parental survival. Reproductive trade-offs may therefore ensue for gravid females, because temperatures conducive to embryonic development may compromise females' body condition. We tested whether reproduction influenced thermoregulation in female Arizona Bark Scorpions (Centruroides sculpturatus). We predicted that gravid females select higher Tb and thermoregulate more precisely than nonreproductive females. Gravid C. sculpturatus gain body mass throughout gestation, which exposes larger portions of their pleural membrane, possibly increasing their rates of transcuticular water loss in arid environments. Accordingly, we tested whether gravid C. sculpturatus lose water faster than nonreproductive females. We determined the preferred Tb of female scorpions in a thermal gradient and measured water loss rates using flow-through respirometry. Gravid females preferred significantly higher Tb than nonreproductive females, suggesting that gravid C. sculpturatus alter their thermoregulatory behaviour to promote offspring fitness. However, all scorpions thermoregulated with equal precision, perhaps because arid conditions create selective pressure on all females to thermoregulate effectively. Gravid females lost water faster than nonreproductive animals, indicating that greater exposure of the pleural membrane during gestation enhances the desiccation risk of reproductive females. Our findings suggest that gravid C. sculpturatus experience a trade-off, whereby selection of higher Tb and increased mass during gestation increase females' susceptibility to water loss, and thus their mortality risk. Elucidating the mechanisms that influence thermal preferences may reveal how reproductive trade-offs shape the life history of ectotherms in arid environments.


Asunto(s)
Temperatura Corporal/fisiología , Escorpiones/fisiología , Animales , Ritmo Circadiano/fisiología , Femenino , Masculino , Reproducción/fisiología
7.
Gene Ther ; 21(8): 739-50, 2014 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-24871581

RESUMEN

We have investigated the ability of hepatitis C virus non-structural (NS) 3/4A-DNA-based vaccines to activate long-term cell-mediated immune responses in mice. Wild-type and synthetic codon optimized (co) NS3/4A DNA vaccines have previously been shown to be immunogenic in mice, rabbits and humans, although we have very poor knowledge about the longevity of the immune responses primed. We therefore analyzed the functionality of primed NS3/4A-specific immune responses in BALB/c (H-2(d)) and/or C57BL/6J (H-2(b)) mice 1, 2, 3, 4, 6, 12 and 16 months after the last immunization. Mice were immunized one, two, three or four times using gene gun delivery to the skin or by intramuscular administration. Immunological responses after immunization were monitored by protection against in vivo challenge of NS3/4A-expressing syngeneic tumor cells. In addition, functionality of the NS3/4A-specific T cells was analyzed by a standard cytotoxicity assay. First, we identified a new unique murine H-2(d)-restricted NS3/4A cytotoxic T lymphocyte (CTL) epitope, which enabled us to study the epitope-specific immune responses. Our results show that the coNS3/4A vaccine was highly immunogenic by determination of interferon-γ/tumor necrosis factor-α production and lytic cytotoxic T cells, which could efficiently inhibit in vivo tumor growth. Importantly, we showed that one to four monthly immunizations protected mice from tumor development when challenged up to 16 months after the last immunization. When determining the functionality of NS3/4A-specific T cells in vitro, we showed detectable lytic activity up to 12 months after the last immunization. Thus, NS3/4A-based DNA vaccines activate potent cellular immune responses that are present and function in both BALB/c and C57BL/6J mice up to 12-16 months after the last immunization. The induction of long-term immunity after NS3/4A DNA immunization has not been shown previously and supports the use of NS3/4A in hepatitis C virus vaccine compositions.


Asunto(s)
Inmunidad Adaptativa , Hepacivirus/inmunología , Vacunas de ADN/inmunología , Animales , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Factores de Tiempo , Vacunación/métodos , Vacunas de ADN/administración & dosificación
8.
Nutr Metab Cardiovasc Dis ; 23(3): 227-34, 2013 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-22397878

RESUMEN

BACKGROUND AND AIMS: Nutrition recommendations for type 2 diabetes (T2DM) are partly guided by the postprandial responses elicited by diets varying in carbohydrate (CHO). We aimed to explore whether long-term changes in postprandial responses on low-glycemic-index (GI) or low-CHO diets were due to acute or chronic effects in T2DM. METHODS AND RESULTS: Subjects with diet-alone-treated T2DM were randomly assigned to high-CHO/high-GI (H), high-CHO/low-GI (L), or low-CHO/high-monounsaturated-fat (M) diets for 12-months. At week-0 (Baseline) postprandial responses after H-meals (55% CHO, GI = 61) were measured from 0800 h to 1600 h. After 12 mo subjects were randomly assigned to H-meals or study diet meals (L, 57% CHO, GI = 50; M, 44% CHO, GI = 61). This yielded 5 groups: H diet with H-meals (HH, n = 34); L diet with H- (LH, n = 17) or L-meals (LL, n = 16); and M diet with H- (MH, n = 18) or M meals (MM, n = 19). Postprandial glucose fluctuations were lower in LL than all other groups (p < 0.001). Changes in postprandial-triglycerides differed among groups (p < 0.001). After 12 mo in HH and MM both fasting- and postprandial-triglycerides were similar to Baseline while in MH postprandial-triglycerides were significantly higher than at Baseline (p = 0.028). In LH, triglycerides were consistently (0.18-0.34 mmol/L) higher than Baseline throughout the day, while in LL the difference from Baseline varied across the day from 0.04 to 0.36 mmol/L (p < 0.001). CONCLUSION: Low-GI and low-CHO diets have both acute and chronic effects on postprandial glucose and triglycerides in T2DM subjects. Thus, the composition of the acute test-meal and the habitual diet should be considered when interpreting the nutritional implications of different postprandial responses.


Asunto(s)
Glucemia/análisis , Diabetes Mellitus Tipo 2/dietoterapia , Carbohidratos de la Dieta/administración & dosificación , Triglicéridos/sangre , Adulto , Anciano , Canadá , Dieta , Ácidos Grasos Monoinsaturados/sangre , Femenino , Índice Glucémico , Humanos , Insulina/sangre , Masculino , Persona de Mediana Edad , Periodo Posprandial
9.
Sci Rep ; 13(1): 12652, 2023 Aug 04.
Artículo en Inglés | MEDLINE | ID: mdl-37542057

RESUMEN

Scanning Hall microscopy has been used to search for spontaneous edge fields in geometrically shaped mesa structures etched into the ab surface of Sr2RuO4 single crystals in order to test recent theories of the direction of edge current flow as a function of facet orientation and band filling. We find no evidence for spontaneous edge fields in any of our mesa structures above our experimental noise floor of ± 25 mG. We do, however, observe pronounced vortex clustering at low fields and temperatures, consistent with the established semi-Meissner scenario whereby a long range attractive component to the vortex-vortex interaction arises due, for example, to the multiband nature of the superconductivity. We also see clear evidence for the formation of a square vortex lattice inside square mesa structures above 1.3 K. Our results are discussed in terms of recent relevant experimental results and theoretical predictions.

10.
Anaesthesia ; 72(12): 1565-1567, 2017 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-29130286
11.
Occup Med (Lond) ; 62(5): 385-7, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22638645

RESUMEN

We present a case of non-specific interstitial pneumonia (NSIP) probably caused by exposure to inhaled clozapine powder. The patient worked in a pharmacy and crushed clozapine tablets over several years. She presented with insidious onset of breathlessness and had mild hypoxia. High-resolution computed tomography demonstrated centrilobular nodules with peribronchial consolidation. Lung biopsy revealed a mixed cellular and fibrotic NSIP. Her symptoms and radiological findings resolved once exposure to clozapine powder ceased. The clear temporal relationship between increased exposure to inhaled clozapine and the development of NSIP, followed by the subsequent resolution on cessation of exposure, strongly suggest an occupational cause. Both the active ingredients and the excipients of powdered medicine may be responsible for causing pneumonitis in chronic exposure.


Asunto(s)
Contaminantes Ocupacionales del Aire/toxicidad , Antipsicóticos/toxicidad , Clozapina/toxicidad , Enfermedades Pulmonares Intersticiales/inducido químicamente , Enfermedades Profesionales/inducido químicamente , Exposición Profesional/efectos adversos , Administración por Inhalación , Polvo , Femenino , Humanos , Enfermedades Pulmonares Intersticiales/diagnóstico , Persona de Mediana Edad , Enfermedades Profesionales/diagnóstico , Farmacia , Tomografía Computarizada por Rayos X
12.
AIDS Behav ; 15(6): 1204-19, 2011 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-20668927

RESUMEN

An expanding body of literature explores the role of African church groups in facilitating or hindering the support of people living with AIDS and challenging or contributing to HIV/AIDS-related stigma. Treating church groups as social spaces in which HIV/AIDS-related stigma may potentially be challenged, we systematically review this literature, identifying five themes that highlight the complex and contradictory role of the church as a potential agent of health-enhancing social change. In many ways the church perpetuates HIV/AIDS-related stigma through (i) moralistic attitudes and (ii) its reinforcement of conservative gender ideologies. However some churches have managed move towards action that makes a more positive contribution to HIV/AIDS management through (iii) promoting various forms of social control for HIV prevention, (iv) contributing to the care and support of the AIDS-affected and (v) providing social spaces for challenging stigmatising ideas and practices. We conclude that church groups, including church leadership, can play a key role in facilitating or hindering the creation of supportive social spaces to challenge stigma. Much work remains to be done in developing deeper understandings of the multi-layered factors that enable some churches, but not others, to respond effectively to HIV/AIDS.


Asunto(s)
Cristianismo , Infecciones por VIH/psicología , Prejuicio , Estigma Social , Estereotipo , África del Sur del Sahara , Infecciones por VIH/prevención & control , Humanos , Religión y Psicología , Cambio Social , Medio Social , Aislamiento Social
13.
PLoS One ; 16(2): e0246123, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33577565

RESUMEN

BACKGROUND: Nasal High Flow (NHF) therapy delivers flows of heated humidified gases up to 60 LPM (litres per minute) via a nasal cannula. Particles of oral/nasal fluid released by patients undergoing NHF therapy may pose a cross-infection risk, which is a potential concern for treating COVID-19 patients. METHODS: Liquid particles within the exhaled breath of healthy participants were measured with two protocols: (1) high speed camera imaging and counting exhaled particles under high magnification (6 participants) and (2) measuring the deposition of a chemical marker (riboflavin-5-monophosphate) at a distance of 100 and 500 mm on filter papers through which air was drawn (10 participants). The filter papers were assayed with HPLC. Breathing conditions tested included quiet (resting) breathing and vigorous breathing (which here means nasal snorting, voluntary coughing and voluntary sneezing). Unsupported (natural) breathing and NHF at 30 and 60 LPM were compared. RESULTS: Imaging: During quiet breathing, no particles were recorded with unsupported breathing or 30 LPM NHF (detection limit for single particles 33 µm). Particles were detected from 2 of 6 participants at 60 LPM quiet breathing at approximately 10% of the rate caused by unsupported vigorous breathing. Unsupported vigorous breathing released the greatest numbers of particles. Vigorous breathing with NHF at 60 LPM, released half the number of particles compared to vigorous breathing without NHF.Chemical marker tests: No oral/nasal fluid was detected in quiet breathing without NHF (detection limit 0.28 µL/m3). In quiet breathing with NHF at 60 LPM, small quantities were detected in 4 out of 29 quiet breathing tests, not exceeding 17 µL/m3. Vigorous breathing released 200-1000 times more fluid than the quiet breathing with NHF. The quantities detected in vigorous breathing were similar whether using NHF or not. CONCLUSION: During quiet breathing, 60 LPM NHF therapy may cause oral/nasal fluid to be released as particles, at levels of tens of µL per cubic metre of air. Vigorous breathing (snort, cough or sneeze) releases 200 to 1000 times more oral/nasal fluid than quiet breathing (p < 0.001 with both imaging and chemical marker methods). During vigorous breathing, 60 LPM NHF therapy caused no statistically significant difference in the quantity of oral/nasal fluid released compared to unsupported breathing. NHF use does not increase the risk of dispersing infectious aerosols above the risk of unsupported vigorous breathing. Standard infection prevention and control measures should apply when dealing with a patient who has an acute respiratory infection, independent of which, if any, respiratory support is being used. CLINICAL TRIAL REGISTRATION: ACTRN12614000924651.


Asunto(s)
Espiración , Terapia por Inhalación de Oxígeno/efectos adversos , Terapia por Inhalación de Oxígeno/métodos , Adulto , Pruebas Respiratorias/métodos , COVID-19/terapia , Cánula , Femenino , Humanos , Masculino , Microscopía por Video , Nariz/química , Respiración , Frecuencia Respiratoria
14.
J Gen Virol ; 91(Pt 1): 13-22, 2010 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19889925

RESUMEN

Recent research has revealed that some plant viruses, like many animal viruses, have measurably evolving populations. Most of these viruses have single-stranded positive-sense RNA genomes, but a few have single-stranded DNA genomes. The studies show that extant populations of these viral species are only decades to centuries old. The genera in which they are placed have diverged since agriculture was invented and spread around the world during the Holocene period. We suggest that this is not mere coincidence but evidence that the conditions generated by agriculture during this era have favoured particular viruses. There is also evidence, albeit less certain, that some plant viruses, including a few shown to have measurably evolving populations, have much more ancient origins. We discuss the possible reasons for this clear discordance between short- and long-term evolutionary rate estimates and how it might result from a large timescale dependence of the evolutionary rates. We also discuss briefly why it is useful to know the rates of evolution of plant viruses.


Asunto(s)
Evolución Molecular , Enfermedades de las Plantas/virología , Virus de Plantas/genética , ADN Viral/genética , Filogenia , ARN Viral/genética , Factores de Tiempo
15.
Ann Rheum Dis ; 69(1): 181-5, 2010 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19176545

RESUMEN

OBJECTIVE: To compare the performance of two interferon gamma release assays (IGRAs) and conventional screening tests in patients with inflammatory arthritis undergoing screening for latent tuberculosis infection (LTBI) before treatment with anti-tumour necrosis factor alpha (anti-TNFalpha) compounds. METHODS: Successive patients were subjected to conventional LTBI screening, including a tuberculin skin test (TST). The T-SPOT.TB test was performed on all patients and the QuantiFERON-TB Gold test was performed on a large subset. The results of the IGRAs were compared with the results of conventional screening tests. RESULTS: A total 150 patients were evaluated. The majority (57.9%) had rheumatoid arthritis. Previous vaccination with Bacille Calmette-Guerin was confirmed in 82% of patients. No patient had received prior anti-TB treatment. A total of 57 patients (38.0%) had at least one positive conventional risk factor. In contrast, an unequivocally positive T-SPOT.TB test was seen in only 14/143 (9.8%). There was 98.2% agreement between the two IGRAs. Statistically significant associations were found between each of the IGRAs and both TST and risk history, but not chest x-ray (CXR). A positive IGRA result was significantly associated with increased age. TB was not reactivated in any patient during the follow-up period. INTERPRETATION: This study suggests that IGRAs may be useful when screening for LTBI before anti-TNFalpha therapy in patients with immune-mediated inflammatory diseases. The observations reported here also highlight the inadequate performance of CXR as a marker of LTBI.


Asunto(s)
Antirreumáticos/uso terapéutico , Artritis/inmunología , Interferón gamma/biosíntesis , Tuberculosis Latente/diagnóstico , Factor de Necrosis Tumoral alfa/antagonistas & inhibidores , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Artritis/complicaciones , Artritis/tratamiento farmacológico , Artritis Reumatoide/complicaciones , Artritis Reumatoide/tratamiento farmacológico , Artritis Reumatoide/inmunología , Humanos , Tuberculosis Latente/complicaciones , Tuberculosis Latente/inmunología , Tamizaje Masivo/métodos , Persona de Mediana Edad , Prueba de Tuberculina , Adulto Joven
16.
Phys Rev Lett ; 105(26): 267205, 2010 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-21231712

RESUMEN

We investigate the nonequilibrium behavior of the spin-ice Dy2Ti2O7 by studying its magnetization as a function of the field sweep rate. Below the enigmatic ''freezing'' temperature T(equil)≈600 mK, we find that even the slowest sweeps fail to yield the equilibrium magnetization curve and instead give an initially much flatter curve. For higher sweep rates, the magnetization develops sharp steps accompanied by similarly sharp peaks in the temperature of the sample. We ascribe the former behavior to the energy barriers encountered in the magnetization process, which proceeds via flipping of spins on filaments traced out by the field-driven motion of the gapped, long-range interacting magnetic monopole excitations. The peaks in temperature result from the released Zeeman energy not being carried away efficiently; the resulting heating triggers a chain reaction.

17.
Mutat Res ; 698(1-2): 18-23, 2010 Apr 30.
Artículo en Inglés | MEDLINE | ID: mdl-20307685

RESUMEN

Approximately one-third of IVF cases in the UK are attributed to male factor infertility and in the majority of cases the origin of male infertility is unknown. The integrity of sperm DNA is important both for the success of assisted reproduction and the implications for the off-spring. One type of DNA damage that has not been investigated with respect to fertility outcomes is the adduct N7-methyldeoxyguanosine (N7-MedG), a biomarker for exposure to alkylating agents. A prospective cohort of couples attending for IVF had their N7-MedG levels in sperm measured using an immunoslot blot technique to examine whether sperm N7-MedG levels are associated with male factor infertility, semen quality measures or assisted reproduction outcomes. Sufficient DNA for analysis was obtained from 67/97 couples and N7-MedG was detected in 94% of sperm samples analysed. Men diagnosed with male factor infertility had significantly higher mean levels of N7-MedG in their sperm DNA (P=0.03). Logistic regression analysis showed that N7-MedG levels were significantly negatively associated with the proportion of oocytes successfully fertilised irrespective of the method of fertilisation used (IVF or intra-cytoplasmic sperm injection; ICSI, P<0.001). Therefore exposure to DNA alkylating agents is significantly associated with male infertility and the proportion of oocytes fertilised during assisted reproduction. Reducing such exposure may improve male fertility but further work is required to determine the relative importance of exogenous and endogenous sources of exposure.


Asunto(s)
Metilación de ADN , Infertilidad Masculina/genética , Técnicas Reproductivas Asistidas , Espermatozoides/ultraestructura , Adulto , Alquilantes/análisis , Aductos de ADN/análisis , Desoxiguanosina/análogos & derivados , Femenino , Guanina/análogos & derivados , Guanina/análisis , Humanos , Masculino , Persona de Mediana Edad
18.
Dalton Trans ; 49(29): 10069-10083, 2020 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-32658230

RESUMEN

Two new lithium-magnesium phosphates LiMg6(PO4)3(P2O7) and Li(Mg5.62Sc0.19Li0.19)(PO4)3(P2O7) were synthesized by a solid-phase method. Using high-resolution time-of-flight neutron powder diffraction (TOF NPD) and X-ray powder diffraction (XRPD), we established that these phosphates have a Pnma orthorhombic structure with the cell parameters a = 9.14664(5) Å, b = 18.83773(8) Å, c = 8.27450(4) Å, and V = 1425.71(1) Å3 and a = 9.14516(5) Å, b = 18.84222(9) Å, c = 8.28204(4) Å, and V = 1427.12(1) Å3, respectively. The crystal structures can be described by stacking of the [Mg6O18]∞ or [Mg5.62Sc0.19Li0.19O18]∞ wavy layers, which are parallel to the (100) direction and interconnected through PO4 tetrahedra and P2O7 groups to form a 3D-framework. The Li atoms are located in large tunnels formed in a 3D lattice, which contributes to lithium diffusion. AC impedance spectroscopy analysis shows that LiMg6(PO4)3(P2O7) and Li(Mg5.62Sc0.19Li0.19)(PO4)3(P2O7) have a Li ion conductivity of 3.6 × 10-4 S cm-1 and 1.7 × 10-4 S cm-1 at 950 °C, with an activation energy of 1.28 eV and 1.55 eV, respectively. NMR MAS studies confirmed the coexistence of pyro- and orthogroups in the structure of both phases and two lithium positions in Li(Mg5.62Sc0.19Li0.19)(PO4)3(P2O7). The first-principles method was used to study the electronic structure and stability of the two phases. The calculated formation enthalpies demonstrated that Sc is a stabilizing impurity in LiMg6(PO4)3(P2O7), while a strong destabilization of olivine LiMgPO4 is observed upon doping with Sc. This explains the failure to synthesize Sc-doped olivine. The new phosphate LiMg6(PO4)3(P2O7) is a dielectric with a band gap of 5.35 eV, which decreases to 4.85 eV due to the appearance of a localized Sc 3d peak upon doping with Sc. These findings are consistent with the results obtained by UV-Vis spectroscopy. The new phase may be a good optical matrix similar to LiMgPO4.

19.
Br J Surg ; 96(7): 778-84, 2009 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-19526612

RESUMEN

BACKGROUND: Sacral nerve stimulation (SNS) is an effective treatment for faecal incontinence, but only standard stimulation parameters have been used. This study assessed the clinical impact of altering the parameters. METHODS: Twelve patients with partially improved faecal incontinence following SNS underwent acute testing to select optimal stimulation parameters; rectal compliance was used as a surrogate marker. Parameters tested were: stimulation off; frequency 14 (standard), 31 or 6.9 Hz; and pulse duration 210 (standard), 450 or 90 micros. Patients completed a 2-week bowel diary, St Mark's continence score (SMCS) and Rockwood faecal incontinence quality-of-life (FIQL) score before testing using standard settings, and after testing using optimized settings. RESULTS: Optimal settings, determined by greatest increase in rectal compliance, were shorter pulse width in five patients and higher frequency in seven. Optimized stimulation resulted in a decrease in mean episodes of incontinence from 2.3 to 1.2 per week (P = 0.031), soiling from 3.3 to 1.7 days per week (P = 0.016), faecal urgency from 31 to 18 per cent of all evacuations (P = 0.055) and SMCS from 12.3 to 8.7 (P = 0.008); the FIQL coping/behaviour score improved (P = 0.008). CONCLUSION: With a shorter pulse width and higher frequency, clinical efficacy in patients undergoing SNS for faecal incontinence can be improved.


Asunto(s)
Terapia por Estimulación Eléctrica/métodos , Incontinencia Fecal/terapia , Plexo Lumbosacro , Adulto , Anciano , Análisis de Varianza , Métodos Epidemiológicos , Femenino , Humanos , Persona de Mediana Edad , Calidad de Vida , Resultado del Tratamiento
20.
Science ; 293(5536): 1842-5, 2001 Sep 07.
Artículo en Inglés | MEDLINE | ID: mdl-11546876

RESUMEN

When gene sequences from the influenza virus that caused the 1918 pandemic were first compared with those of related viruses, they yielded few clues about its origins and virulence. Our reanalysis indicates that the hemagglutinin gene, a key virulence determinant, originated by recombination. The "globular domain" of the 1918 hemagglutinin protein was encoded by a part of a gene derived from a swine-lineage influenza, whereas the "stalk" was encoded by parts derived from a human-lineage influenza. Phylogenetic analyses showed that this recombination, which probably changed the virulence of the virus, occurred at the start of, or immediately before, the pandemic and thus may have triggered it.


Asunto(s)
Glicoproteínas Hemaglutininas del Virus de la Influenza/genética , Virus de la Influenza A/genética , Virus de la Influenza A/patogenicidad , Gripe Humana/epidemiología , Gripe Humana/virología , Recombinación Genética/genética , Animales , Evolución Molecular , Glicoproteínas Hemaglutininas del Virus de la Influenza/química , Glicoproteínas Hemaglutininas del Virus de la Influenza/metabolismo , Humanos , Método de Montecarlo , Mutación/genética , Filogenia , Estructura Terciaria de Proteína , Porcinos/virología , Estados Unidos/epidemiología
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