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The seventh-century AD switch from gold to silver currencies transformed the socio-economic landscape of North-west Europe. The source of silver, however, has proven elusive. Recent research, integrating ice-core data from the Colle Gnifetti drill site in the Swiss Alps, geoarchaeological records and numismatic and historical data, has provided new evidence for this transformation. Annual ice-core resolution data are combined with lead pollution analysis to demonstrate that significant new silver mining facilitated the change to silver coinage, and dates the introduction of such coinage to c. AD 660. Archaeological evidence and atmospheric modelling of lead pollution locates the probable source of the silver to mines at Melle, in France.
Depression and diabetes commonly co-occur; however, the strength of the physiological effects of diabetes as mediating factors towards depression is uncertain.
We analyzed extensive clinical, epidemiological and laboratory data from n = 2081 Mexican Americans aged 35–64 years, recruited from the community as part of the Cameron County Hispanic Cohort (CCHC) divided into three groups: Diagnosed (self-reported) diabetes (DD, n = 335), Undiagnosed diabetes (UD, n = 227) and No diabetes (ND, n = 1519). UD participants denied being diagnosed with diabetes, but on testing met the 2010 American Diabetes Association and World Health Organization definitions of diabetes. Depression was measured using the Center for Epidemiological Studies – Depression (CES-D) scale. Weighted data were analyzed using dimensional and categorical outcomes using univariate and multivariate models.
The DD group had significantly higher CES-D scores than both the ND and UD (p ⩽ 0.001) groups, whereas the ND and UD groups did not significantly differ from each other. The DD subjects were more likely to meet the CES-D cut-off score for depression compared to both the ND and UD groups (p = 0.001), respectively. The UD group was also less likely to meet the cut-off score for depression than the ND group (p = 0.003). Our main findings remained significant in models that controlled for socio-demographic and clinical confounders.
Meeting clinical criteria for diabetes was not sufficient for increased depressive symptoms. Our findings suggest that the ‘knowing that one is ill’ is associated with depressive symptoms in diabetic subjects.
This study aimed to estimate the prevalence and risk factors for hepatitis C virus (HCV) infection in Mexican Americans living in South Texas. We tested plasma for the presence of HCV antibody from the Cameron County Hispanic Cohort (CCHC), a randomized, population-based cohort in an economically disadvantaged Mexican American community on the United States/Mexico border with high rates of chronic disease. A weighted prevalence of HCV antibody of 2·3% [n = 1131, 95% confidence interval (CI) 1·2–3·4] was found. Participants with diabetes had low rates of HCV antibody (0·4%, 95% CI 0·0–0·9) and logistic regression revealed a statistically significant negative association between HCV and diabetes (OR 0·20, 95% CI 0·05–0·77) after adjusting for sociodemographic and clinical factors. This conflicts with reported positive associations of diabetes and HCV infection. No classic risk factors were identified, but important differences between genders emerged in analysis. This population-based study of HCV in Mexican Americans suggests that national studies do not adequately describe the epidemiology of HCV in this border community and that unique risk factors may be involved.
Transmission of hepatitis C (HCV) in Pakistan is a continuing public health problem; 15 years ago it was linked to the practice of reusing therapeutic instruments in healthcare settings. We sought to examine current risk factors for HCV transmission in a hospital population in Karachi, Pakistan. We enrolled 300 laboratory-confirmed HCV-positive participants and 300 laboratory-confirmed HCV-negative participants from clinics at Indus Hospital. Independent and significant risk factors for both men and women were: receiving ⩾12 injections in the past year, blood transfusions, having had dental work performed, and delivery in hospital or transfusion for women. Interestingly, being of Mohajir origin or born in Sindh province were protective. Encouragingly, a strong protective effect was observed for those that reported bringing their own needle for injections (59%). The widespread reuse of therapeutic needles in healthcare settings in Karachi remains a major driver of the HCV epidemic.
Studies of temporal and spatial patterns of diarrhoeal disease can suggest putative aetiological agents and environmental or socioeconomic drivers. Here, the seasonal patterns of monthly acute diarrhoeal morbidity in Thailand, where diarrhoeal morbidity is increasing, are explored. Climatic data (2003–2006) and Thai Ministry of Health annual reports (2003–2009) were used to construct a spatially weighted panel regression model. Seasonal patterns of diarrhoeal disease were generally bimodal with aetiological agents peaking at different times of the year. There is a strong association between daily mean temperature and precipitation and the incidence of hospitalization due to acute diarrhoea in Thailand leading to a distinct spatial pattern in the seasonal pattern of diarrhoea. Model performance varied across the country in relation to per capita GDP and population density. While climatic factors are likely to drive the general pattern of diarrhoeal disease in Thailand, the seasonality of diarrhoeal disease is dampened in affluent urban populations.
Diarrhoeal mortality rates in Mexican children dramatically declined during the 1980s and 1990s, concomitant with a temporal shift in peak deaths from summer to autumn–winter. The spatial dynamics of these patterns have not previously been studied. We first describe the seasonal features of paediatric diarrhoeal mortality in Mexico as a whole, then across individual states. While no geographical gradients in the magnitude of diarrhoeal mortality rates have been detected in recent years, we identified a distinct spatial pattern in the timing of peak mortality rate. In the 1980s the summer peak mortality was earliest around Mexico's capital and later in states to the southeast and northwest. Our results suggest that the direction and timing of those annual waves are related to the mean monthly precipitation and mean daily temperature. This pattern has disintegrated in recent years as the summer peak has diminished.
Irradiation with high energy heavy ion beams has been investigated as a technique for improving the quality of highly reflecting metallic surfaces to be used as laser mirrors. Properties such as reflectivity, corrosion resistance, film bonding, and threshold to laser surface damage have been examined. Modifications of composition and microstructure of the material associated with the heavy ion irradiation have been measured with RBS, TEM, SEM, Auger, and ESCA. Reflectivity and extinction coefficient measurements were made using ellipsometry techniques. Observations indicate that keV heavy ion irradiations in the fluence range of 1015 to 1016 cm−2 produce significant surface smoothing. Additionally, MeV implants of heavy ions into films of Cu, Ag, Au and Al deposited on molybdenum substrates resulted in improvements to both tarnish resistance and structural bonding integrity.
Investigation of the interactions in two magnetic composite systems composed of ∼8 vol% isolated Sm2Co17 nanoparticles of different size ranges in a CaO matrix has been made by comparing the isothermal remanent magnetization curves (IRM) with the dc demagnetization curves (DCD) using Wohlfarth remanence relation. The presence of a weak demagnetizing field was evidenced in the sample with smaller magnetic particles (7-90nm), indicating the magnetostatic interaction between the magnetic particles was dominant in this sample. The large positive deviation from Wolhfarth relation in the sample with larger particles (10-250nm) suggests the presence of multigrain particles in which neighboring grains interact strongly with each other. The hysteresis curves of the two composite systems were measured at temperatures between 5 and 350K. A nearly linear temperature dependence of the coercivity was observed in both samples up to 350 K. From these results it is shown that although the sizes of the Sm2Co17 particles are well below the critical size for single domain particle, there is no evidence that the magnetization reversals in these particles are coherent rotation.
Melt-quenched NdFeB is an important modem permanent magnet material. However there still remains doubt as to the magnetization reversal mechanism which controls coercivity in material prepared by this processing route. To investigate this problem a new technique based on measurements of reversible magnetization along recoil curves has been used. The technique identifies the presence of free domain walls during magnetic reversal. For this study samples of isotropic (MQI), hot pressed (MQII) and die upset (MQIII) melt-quenched NdFeB were examined. The results indicate that in MQI free domain walls are not present during reversal and the reversal mechanism is most likely incoherent rotation of some form. Free domain walls are also not present during reversal in the majority of grains of MQII, even though initial magnetization measurements indicate that the grain size is large enough to support them. In MQIII free domain walls are present during reversal. These results are attributed to the reduced domain wall nucleation field in MQII compared with MQII and the increased dipolar interactions in MQIII.
Starting from two-step anodizing recipes available in the literature, we fabricated selfsupporting ordered ion-implantation masks that are several mm2 in area and 1-4 νm thick. SEM micrographs reveal self-organized structures with straight open pores, 25-150 nm in diameter, extending completely through the mask. As reported previously, the pore diameter and spacing depend critically upon the anodization parameters, e.g., type of acid and its molality, the applied voltage and the solution temperature. Ion-milling procedures were developed for opening the bottoms of the anodized pores. These masks appear quite robust during exposure to ion beams of 1-MeV He, Ne, and Kr. The steps necessary to fabricate the implantation masks, including opening the pores, are briefly described. Here we present new results obtained with a mask fabricated with pore dimensions as small as 25 nm in diameter, i.e., at the limit of what is technically feasible. Measurements are reported of the angular dependence of the transmitted ion current; these results are consistent with the physical dimensions of the opened pores. TEM images of a partial array obtained by implantation through the 25-nm pores are also shown.
The following is a brief description of the reconstructive options available to patients undergoing mastectomy, and a review of the data available to guide clinicians who seek to safely integrate postmastectomy radiotherapy and breast reconstruction.
The epidemic of type 2 diabetes in the United States prompted us to explore the association between diabetes and tuberculosis (TB) on the South Texas–Mexico border, in a large population of mostly non-hospitalized TB patients. We examined 6 years of retrospective data from all TB patients (n=5049) in South Texas and northeastern Mexico and found diabetes self-reported by 27·8% of Texan and 17·8% of Mexican TB patients, significantly exceeding national self-reported diabetes rates for both countries. Diabetes comorbidity substantially exceeded that of HIV/AIDS. Patients with TB and diabetes were older, more likely to have haemoptysis, pulmonary cavitations, be smear positive at diagnosis, and remain positive at the end of the first (Texas) or second (Mexico) month of treatment. The impact of type 2 diabetes on TB is underappreciated, and in the light of its epidemic status in many countries, it should be actively considered by TB control programmes, particularly in older patients.
Household members of people with hepatitis C are at increased risk of HCV infection. The
prevalence and routes of transmission of HCV to household members in Hafizabad, Pakistan
were investigated. Household members of 24 index cases were given a risk factor questionnaire,
tested for HCV infection, and the risk factors between the infected and uninfected were
compared. Twelve of 74 household members (16·2%) were seropositive for HCV antibody.
This was 2½ times the rate of infection in the general population (OR=2·8; P=0·01). None of
the routes of transmission studied within the household was associated with an increased risk.
Household members who received more than 4 injections per year were 11·9 times more likely
to be infected than those who had not (P=0·016). In Hafizabad, the greatest risk for HCV
infection to household members of infected people is injections given by health-care workers
rather than household contact with infected persons.
We conducted a study to evaluate risk factors for developing typhoid
fever in a setting where
the disease is endemic in Karachi, Pakistan. We enrolled 100 cases with
culture-confirmed Salmonella typhi between July and October 1994
and 200 age-matched
neighbourhood controls. Cases had a median age of 5·8 years. In
a conditional logistic
regression model, eating ice cream (Odds ratio [OR]=2·3;
95% confidence interval [CI]
1·2–4·2, attributable risk [AR]=36%),
eating food from a roadside cabin during the summer
months (OR=4·6, 95% CI 1·6–13·0; AR=18%),
taking antimicrobials in the 2 weeks
preceding the onset of symptoms (OR=5·7, 95% CI
2·3–13·9, AR=21%), and drinking
water at the work-site (OR=44·0, 95% CI 2·8–680,
AR=8%) were all independently
associated with typhoid fever. There was no difference in the microbiological
water quality of
home drinking water between cases and controls. Typhoid fever in Karachi
high-dose exposures from multiple sources with individual susceptibility
increased by young age and
prior antimicrobial use. Improving commercial food hygiene and decreasing
antimicrobial use would be expected to decrease the burden of typhoid fever.
Surface-tension-driven Bénard (Marangoni) convection
in liquid layers heated from
below can exhibit a long-wavelength primary instability that differs from
familiar hexagonal instability associated with Bénard. This
is predicted to be significant in microgravity and for thin liquid
layers. The instability
is studied experimentally in terrestrial gravity for silicone oil layers
0.007 to 0.027 cm
thick on a conducting plate. For shallow liquid depths (<.017 cm for
0.102 cm2 s−1 viscosity liquid), the
system evolves to a strongly deformed long-wavelength
state which can take the form of a localized depression (‘dry spot’)
or a localized elevation (‘high spot’), depending on the thickness
and thermal conductivity of the
gas layer above the liquid. For slightly thicker liquid depths
the formation of a dry spot induces the formation of hexagons. For even
liquid depths (>0.024 cm), the system forms only the hexagonal convection
A two-layer nonlinear theory is developed to account properly for the effect
deformation on the interface temperature profile. Experimental results
long-wavelength instability are compared to our two-layer theory and to
theory that accounts for the upper gas layer solely with a heat transfer
The two-layer model better describes the onset of instability and also
formation of localized elevations, which the one-layer model does not predict.
weakly nonlinear analysis shows that the bifurcation is subcritical.
Solving for steady states of the system shows that the subcritical pitchfork
bifurcation curve never turns
over to a stable branch. Numerical simulations also predict a subcritical
and yield long-wavelength states that qualitatively agree with the experiments.
observations agree with the onset prediction of the two-layer model, except
thin liquid layers; this deviation from theory may arise from small non-uniformities
in the experiment. Theoretical analysis shows that a small non-uniformity
produces a large steady-state deformation (seen in the experiment) that
more pronounced with increasing temperature difference across the liquid.
steady-state deformation becomes unstable to the long-wavelength instability
smaller temperature difference than that at which the undeformed state
unstable in the absence of non-uniformity.
Recent studies suggest that larger brain size may offer some protection against the clinical manifestations of Alzheimer's disease. However, this association has not been investigated in population-based studies.
The relationship between head circumference, a measure of premorbid brain size, and score on the Cognitive Abilities Screening Instrument (CASI) was studied in a population of 1985 Japanese–Americans aged 65+ living in King County, Washington, USA.
After adjusting for age, sex and education, head circumference was positively associated with CASI score (b=3.8, 95% CI: 2.2, 5.4; P=0.0000), but not with diagnosis of probable AD (odds ratio=0.87, 95% CI: 0.33, 1.87). When the data were stratified by AD status, no association was seen among controls (b=1.6, 95% CI: – 1.7, 5.1; P=0.4), whereas a strong effect was present among cases (b=35.3, 95% CI: 12.2, 58.4: P=0.006).
These results suggest that persons with AD with smaller head circumference either had the disease longer or progressed more rapidly than those with larger head circumference. Improvement in environmental factors in prenatal and early life that partially determine completed brain/head size may have consequences for the late-life expression of Alzheimer's disease in vulnerable individuals.