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Lake Untersee is one of the largest perennially ice-covered lakes in Dronning Maud Land. We investigated the energy and water mass balance of Lake Untersee to understand its state of equilibrium. The thickness of the ice cover is strongly correlated with sublimation rates; variations in sublimation rates across the ice cover are largely determined by wind-driven turbulent heat fluxes and the number of snow-covered days. Lake extent and water level have remained stable for the past 20 years, indicating that the water mass balance is in equilibrium. The lake is damned by the Anuchin Glacier and mass balance calculation suggest that subaqueous melting of terminus ice contributes 40–45% of the annual water budget; since there is no evidence of streams flowing into the lake, the lake must be connected to a groundwater system that contributes 55–60% in order to maintain the lake budget in balance. The groundwater likely flows at a rate of ~8.8 × 10−2 m3 s−1, a reasonable estimate given the range of subglacial water flux in the region. The fate of its well-sealed ice cover is likely tied to changes in wind regime, whereas changes in water budget are more closely linked to the response of surrounding glaciers to climate change.
Much of suicide research focuses on suicide attempt (SA) survivors. Given that more than half of the suicide decedent population dies on their first attempt, this means a significant proportion of the population that dies by suicide is overlooked in research. Little is known about persons who die by suicide on their first attempt–and characterizing this understudied population may improve efforts to identify more individuals at risk for suicide.
Data were derived from the National Violent Death Reporting System, from 2005 to 2013. Suicide cases were included if they were 18–89 years old, with a known circumstance leading to their death based on law enforcement and/or medical examiner reports. Decedents with and without a history of SA were compared on demographic, clinical, and suicide characteristics, and circumstances that contributed to their suicide.
A total of 73 490 cases met criteria, and 57 920 (79%) died on their first SA. First attempt decedents were more likely to be male, married, African-American, and over 64. Demographic-adjusted models showed that first attempt decedents were more likely to use highly lethal methods, less likely to have a known mental health problem or to have disclosed their intent to others, and more likely to die in the context of physical health or criminal/legal problem.
First attempt suicide decedents are demographically different from decedents with a history of SA, are more likely to use lethal methods and are more likely to die in the context of specific stressful life circumstances.
High-resolution measurements of the molybdenum L heavy-ion-induced X-ray satellite emission (HIXSE) spectra of a series of Mo alloys and compounds have been obtained with a new, high-efficiency, high-resolution Bragg crystal spectrometer in the von Hamos geometry. The improved resolution (5 eV at 2.3 keV) is sufficient to reveal the LnMm configuration lines in the Lα and Lβ hypersatellite bands. Both sets of lines exhibit the same trend in the variation of the relative yield distribution with the chemical environment as was observed for KLn lines of lower Z targets. Difference spectra, using elemental molybdenum as a subtrahend, enhance the systematic variation. These results confirm the analysis and conclusions of lower resolution studies. They also indicate a potential for even greater sensitivity to the chemical environment.
In experimental and clinical studies, green or black tea consumption has been shown to reduce oxidative stress. However, these studies involved high levels of tea consumption and may not reflect patterns in the general population. Here, we examined the association between black or green tea consumption and oxidative stress in a cross-sectional study of 889 premenopausal US women aged 35–54 years. Tea consumption was measured using the Block-98 FFQ. Urinary 8-iso-PGF2α (F2-IsoP) and 2,3-dinor-5,6-dihydro-15-F2t-isoprostane (15-F2t-IsoP-M) were used as biomarkers of oxidative stress. These compounds were measured by MS and normalised to creatinine. Linear regression was used to calculate the geometric mean differences (GMD) and 95% CI for log-transformed urinary F2-IsoP or 15-F2t-IsoP-M in relation to black or green tea consumption. We further examined whether adjusting for caffeine impacted associations between tea and oxidative stress. Geometric means of urinary F2-IsoP and 15-F2t-IsoP-M were 1·44 (95% CI 1·39, 1·49) and 0·71 (95% CI 0·69, 0·73) ng/mg creatinine, respectively. Overall, green tea consumption was not associated with urinary F2-IsoP or 15-F2t-IsoP-M. High-level black tea consumption (≥5 cups/week compared with 0) was associated with higher 15-F2t-IsoP-M concentrations (adjusted GMD=0·10, 95 % CI 0·02–0.19) but not F2-IsoP. Adjusting for caffeine nullified the association between black tea and 15-F2t-IsoP-M. Our findings do not support the hypothesis that dietary tea consumption is inversely associated with oxidative stress.
Lake Untersee is a perennially ice-covered Antarctic lake that consists of two basins. The deepest basin, next to the Anuchin Glacier is aerobic to its maximum depth of 160 m. The shallower basin has a maximum depth of 100 m, is anoxic below 80 m, and is shielded from convective currents. The thermal profile in the anoxic basin is unusual in that the water temperature below 50 m is constant at 4°C but rises to 5°C between 70 m and 80 m depth, then drops to 3.7°C at the bottom. Field measurements were used to conduct a thermal and stability analysis of the anoxic basin. The shape of the thermal maximum implies two discrete locations of energy input, one of 0.11 W m-2 at 71 m depth and one of 0.06 W m-2 at 80 m depth. Heat from microbial activity cannot account for the required amount of energy at either depth. Instead, absorption of solar radiation due to an increase in water opacity at these depths can account for the required energy input. Hence, while microbial metabolism is not an important source of heat, biomass increases opacity in the water column resulting in greater absorption of sunlight.
There is remarkably little documented information in the scientific literature on any of the 18 species of buttonquail as they are very difficult to observe in the wild. This lack of information has hampered informed conservation decision making. We undertook the first biome-wide survey for the fynbos endemic Hottentot Buttonquail Turnix hottentottus, using flush transect surveys covering 275 km. We used location data for sightings as well as from records reported by the bird-watching community and modelled distribution using MaxEnt. Encounters were restricted to the fynbos biome, and the top contributors to our prediction of suitable habitat were habitat transformation, slope and time since fire. We obtained a density estimate of 0.032 individuals per hectare which, across an estimated median range of 27,855 km2, provides a population estimate of 89,136 individuals. Given the extent of the range and the population estimate we suggest the IUCN Red List status could be ‘Vulnerable’, rather than ‘Endangered’. Agricultural and alien-vegetation encroachment means that the future of the species is certainly under threat and further studies are needed to inform conservation management.
To determine the impact of recurrent Clostridium difficile infection (RCDI) on patient behaviors following illness.
Using a computer algorithm, we searched the electronic medical records of 7 Chicago-area hospitals to identify patients with RCDI (2 episodes of CDI within 15 to 56 days of each other). RCDI was validated by medical record review. Patients were asked to complete a telephone survey. The survey included questions regarding general health, social isolation, symptom severity, emotional distress, and prevention behaviors.
In total, 119 patients completed the survey (32%). On average, respondents were 57.4 years old (standard deviation, 16.8); 57% were white, and ~50% reported hospitalization for CDI. At the time of their most recent illness, patients rated their diarrhea as high severity (58.5%) and their exhaustion as extreme (30.7%). Respondents indicated that they were very worried about getting sick again (41.5%) and about infecting others (31%). Almost 50% said that they have washed their hands more frequently (47%) and have increased their use of soap and water (45%) since their illness. Some of these patients (22%–32%) reported eating out less, avoiding certain medications and public areas, and increasing probiotic use. Most behavioral changes were unrelated to disease severity.
Having had RCDI appears to increase prevention-related behaviors in some patients. While some behaviors are appropriate (eg, handwashing), others are not supported by evidence of decreased risk and may negatively impact patient quality of life. Providers should discuss appropriate prevention behaviors with their patients and should clarify that other behaviors (eg, eating out less) will not affect their risk of future illness.
This study investigated long-term survival outcomes in surgically treated oropharyngeal cancer patients with known human papilloma virus status.
A case note review was performed of all patients undergoing primary surgery for oropharyngeal cancer in a single centre over a 10-year period. Human papilloma virus status was determined via dual modality testing. Associations between clinicopathological variables and survival were identified using a log-rank test.
Of the 107 cases in the study, 40 per cent (n = 41) were human papilloma virus positive. The positive and negative predictive values of p16 immunohistochemistry for human papilloma virus status were 57 per cent and 100 per cent, respectively. At a mean follow up of 59.5 months, 5-year overall and disease-specific survival estimates were 78 per cent and 69 per cent, respectively. Human papilloma virus status (p = 0.014), smoking status (p = 0.021) and tumour stage (p = 0.03) were significant prognostic indicators.
The long-term survival rates in surgically treated oropharyngeal cancer patients were comparable to other studies. Variables including human papilloma virus status and tumour stage were associated with survival in patients treated with primary surgery; however, nodal stage and presence of extracapsular spread were non-prognostic.
Takotsubo cardiomyopathy has been associated with the use of catecholamines; however, its development after the use of nebulised adrenaline for the management of acute airway obstruction has not previously been described.
A 66-year-old man with squamous cell carcinoma of the larynx, with tumour–node–metastasis staging of T3N2cM0, confirmed by biopsy and computed tomography, presented to the emergency department with acute airway obstruction. He was treated twice with nebulised adrenaline and intravenous dexamethasone. After a period of 24 hours, cardiac rhythm changes were noted on telemetry. A 12-lead electrocardiogram showed widespread T-wave inversion and QT prolongation suggestive of an acute coronary syndrome. Coronary angiography demonstrated no coronary artery disease, but left ventricular angiography showed marked apical ballooning and apical wall akinesia consistent with a diagnosis of takotsubo cardiomyopathy.
Takotsubo cardiomyopathy can mimic true ischaemic heart disease and the diagnosis requires a high index of suspicion in patients managed with nebulised adrenaline.
The structure of stated preference questions to value consumption from public infrastructure can vary depending on the conditions of consumption facing the household. Specifically, a good could be offered as a quasi-public or quasi-private good. This paper demonstrates how consumption from two alternative electricity allocation options can be valued using two types of stated preference questions. Since surveyed households were asked two types of questions, the authors develop a joint model of a contingent valuation question and a contingent quantity behavior response that allows for correlation in error terms across models. In their application to two villages in Rwanda, the authors find higher WTP for electricity consumed as a quasi-private good rather than a quasi-public good, with four hours of electricity per day, only in the evening. They also find correlation in the error terms across the two models, suggesting that their joint estimator is more efficient than estimating each model individually.
A systematic review was performed to evaluate the safety and efficacy of different therapeutic interventions available for the management of isolated cricopharyngeal dysfunction.
Studies were identified using the following databases: Ovid (Medline, Embase), the Cochrane Library, PubMed and Google Scholar. An initial search identified 339 articles. All titles and abstracts were reviewed. Fifty-six relevant articles were inspected in more detail; of these, 47 were included in the qualitative analysis.
No relevant randomised trials were found. A range of case series were used to perform a qualitative analysis. Botulinum toxin A injection and cricopharyngeal dilatation were associated with a higher risk of recurrence, but appear to be more suitable in elderly and co-morbid patients. In those patients requiring formal myotomy, endoscopic approaches appear to be as effective but less morbid when compared with classical open surgery.
There is good evidence for the safety and efficacy of the different therapeutic options for isolated cricopharyngeal dysfunction. However, further studies are required to compare the efficacy of the various treatment modalities.
Cognitive dysfunction is common in major depressive disorder (MDD) and a critical determinant of health outcome. Anhedonia is a criterion item toward the diagnosis of a major depressive episode (MDE) and a well-characterized domain in MDD. We sought to determine the extent to which variability in self-reported cognitive function correlates with anhedonia.
A post hoc analysis was conducted using data from (N=369) participants with a Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision (DSM-IV-TR)-defined diagnosis of MDD who were enrolled in the International Mood Disorders Collaborative Project (IMDCP) between January 2008 and July 2013. The IMDCP is a collaborative research platform at the Mood Disorders Psychopharmacology Unit, University of Toronto, Toronto, Canada, and the Cleveland Clinic, Cleveland, Ohio. Measures of cognitive function, anhedonia, and depression severity were analyzed using linear regression equations.
A total of 369 adults with DSM-IV-TR–defined MDD were included in this analysis. Self-rated cognitive impairment [ie, as measured by the Adult ADHD Self-Report Scale (ASRS)] was significantly correlated with a proxy measure of anhedonia (r=0.131, p=0.012). Moreover, total depression symptom severity, as measured by the total Montgomery–Åsberg Depression Rating Scale (MADRS) score, was also significantly correlated with self-rated measures of cognitive dysfunction (r=0.147, p=0.005). The association between anhedonia and self-rated cognitive dysfunction remained significant after adjusting for illness severity (r=0.162, p=0.007).
These preliminary results provide empirical data for the testable hypothesis that anhedonia and self-reported cognitive function in MDD are correlated yet dissociable domains. The foregoing observation supports the hypothesis of overlapping yet discrete neurobiological substrates for these domains.
Monoclinic Cu2SnS3 was made by solution based processing of the precursor metals after which the samples are annealed in a sulphur environment. XRD and Raman spectra shows that the monoclinic phase was synthesised. One sample was further etched in KCN and HCl to remove possible secondary phases. Transmission spectra show that the material has two optical transitions and in conjunction with reflection data absorption spectra were calculated. The two optical transitions are determined to be 0.91 and 0.98 for the unetched sample and 0.90 and 0.95 eV for the etched sample. The values of the optical transitions are within the error the same and thus etching does not affect the values of these optical transitions. Photoluminescence spectra map show only one luminescence peak with a maximum at 0.95 eV, which is consistent with the values found by absorption spectra. This in combination with the Raman spectra and XRD indicates that the sample contains only one polymorph of Cu2SnS3, which is monoclinic. Therefore the two optical transitions are intrinsic to monoclinic Cu2SnS3.
The molecular epidemiology of pediatric Clostridium difficile infection (CDI) is poorly understood. We aimed to identify the restriction endonuclease analysis (REA) groups causing CDI and to determine risk factors and outcomes associated with CDI caused by epidemic strains in children.
Retrospective cohort study
Inpatients and outpatients >1 year old receiving care between December 2012 and December 2013
An academic children’s hospital in Chicago, Illinois
C. difficile PCR-positive stools were cultured, and C. difficile isolates were typed by REA. REA of isolates from patients with multiple CDIs was performed to differentiate relapse (infection with same strain) from reinfection (different strains) irrespective of time between CDIs.
A total of 189 CDIs occurred among 145 patients. REA groups were widely distributed. The BI/NAP1/027 strain caused CDI in only 1 patient. DH/NAP11/106, the predominant epidemic strain identified, was associated with the use of third- or fourth-generation cephalosporins (risk ratio [RR], 3.2; 95% confidence interval [CI], 1.1–9.9; P=.04). CDI relapse commonly occurred up to 20 weeks later. Compared with CDI caused by non-DH/NAP11/106 strains, CDI caused by DH/NAP11/106 was more likely to result in multiple CDI relapses (40% vs 8%; P=.05) among children with multiple CDIs.
REA identified the exceedingly low prevalence of BI/NAP1/027 and the high prevalence of DH/NAP11/106, a common epidemic strain in the United Kingdom that is less often reported in the United States. CDI relapse commonly occurred up to 20 weeks from the previous CDI. Defining recurrent CDI as that occurring only within 8 weeks of the original infection may lead to misclassification of some recurrent CDIs as new CDIs in children.
Introduction: myths, misunderstandings and challenges
It has become common for ecological studies to recognise the importance of the spatial aspects of ecological systems (e.g. Wagner & Fortin 2005; Schroeder & Seppelt 2006a; Hanski 2009; Leibold 2009; Fortin et al. 2012a; Gelfand 2012), and to include them in the design and analysis of these studies at least conceptually (Legendre et al. 2002, 2004). Spatial effects are various and many may act simultaneously or interdependently, including factors such as spatial scale, autocorrelation, locational and neighbour effects, functional connections, and the ubiquitous mutual interaction between spatial pattern and temporal processes. The set of topics in this constellation of ideas is complex and potentially confusing, especially when time is included as well as space. While the increasing awareness of the importance of spatial effects is helpful, the complexity has given rise to some misunderstandings and to a number of ‘myths’ about the issues and possible solutions. Although careful instruction and clear advice are available in the literature and in a number of textbooks (Cressie 1993; Legendre & Legendre 1998; Haining 2003; Fortin & Dale 2005; Schabenberger & Gotway 2005; Cressie & Wikle 2011), some challenges remain for researchers who face particular kinds of data and particular details of analysis. In this section we will make explicit a few of the prevalent myths about spatial effects, with an attempt to correct the related misunderstandings. Also we will acknowledge the real (not mythical at all!) challenges that including the spatial context presents for ecological studies.
When characterizing spatial pattern, several statistical and ecological concepts come into play and potential mismatches among them can occur in the appropriateness of their usage. Furthermore, a number of other considerations need to be acknowledged.
The topic of diversity in biological systems, whether called ‘species diversity’, ‘ecological diversity’, ‘biological diversity’, or just ‘biodiversity’, is the topic of literally thousands of scientific articles and is included as a central concept, sometimes the main subject, of many books (Huston 1994; Magurran 2004; Rosenzweig 1995; Sarkar 2009; Magurran & McGill 2010). Informally, diversity is related to the variety of classes or categories represented in a collection of objects. The concept comes up in a number of different areas for biological research including genetics, systematics and evolution, conservation biology, and ecology. Biological diversity in ecological systems is a concept of intense interest and of great theoretical as well as practical importance, which has implications for the coexistence of species and the structure of natural communities as well as for the persistence of species in disturbed systems, the conservation of organisms, and the functioning of the systems in which they occur.
In the ecological literature, much of the discussion of diversity has dealt with what the concept means, or should mean, and how the characteristic is, or should be, measured. Diversity thus includes several aspects which make its discussion complex. As early as 1971, Hurlbert wrote a paper on the ‘nonconcept’ of species diversity, suggesting that the idea had been so abused as to become meaningless and that the term should be abandoned. More recently, Huston (1994, p. 64) commented that ‘Far too much attention has been paid to comparison and criticism of statistical methods for quantifying diversity’. We will try to bring clarity to those parts of the discussion needed for spatial diversity analysis, but it is worth remembering Colwell’s recent reminder that the concept of diversity is “a human construct without any unique mathematical meaning” (Colwell 2009). Our own version of the same warning is that even richness, as one aspect of diversity, is a synthetic variable, and we will return to the implications of this fact within a spatial context.
This chapter expands the discussion of the analysis of spatial structure to include the temporal dimension of ecological processes resulting spatial patterns. The intimate relationship between spatial structure and temporal change in ecological systems was eloquently described by Watt (1947) in his famous discourse on pattern and process in plant communities. His theme was that a plant community could be viewed as a working mechanism with the dynamic behaviours of development, degradation, and regeneration. In many plant communities, the various phases of the dynamic process coexist, and may have an identifiable spatial relationship to each other (Figure 11.1). In communities and populations of animals, the relationship between spatial locations and dynamic processes can be even more obvious, as animals move through the spatial structure of their habitat to find resources or mates, and to avoid predators or unfavourable conditions. At the population level, we need to recognize that a population of a given density is not often homogeneously distributed, and that the dynamics of different subpopulations’ densities may be very different depending on location and the conditions found there. At the level of the individual organism and its immediate environment, we need to include the fact that an individual is mostly affected by very local, and less to global, conditions (Fortin et al. 2012a), and that these may change significantly over relatively small distances and over relatively short time periods. In almost any system, our concepts of spatial structure and its importance will include implicitly, if not explicitly, a temporal component.