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Our understanding of land‐based cool season temperature variability over the past millennium is limited by the relative lack of annually resolved temperature proxies, especially in the Southern Hemisphere. Here, we develop the first earlywood (EW) and latewood (LW) width chronologies from Australia based on the Tasmanian endemic conifer Athrotaxis selaginoides in the far southeast of Australia. We also develop total ring width (RW), EW and LW chronologies from a new site in the far south. We compare the climate responses of RW, EW and adjusted LW chronologies of three A. selagnoides sites near the southern extent of the species with three sites of the species near the northern extent of the species. RW and EW at the southern sites are strongly and positively related to cool season temperature (July–October), but in the north, RW and EW are more strongly and positively related with summer (December–February) temperatures. Once adjusted for the influence of the same growing season EW, LW in the north is very strongly negatively correlated with January–February temperatures across southeastern Australia. The new southern RW and EW chronologies can be used to extend one of only two annually resolved regional cool season temperature reconstructions in the Southern Hemisphere back a further 180 years. [ABSTRACT FROM AUTHOR]

Summary: This study aimed to examine the impact of break duration between consecutive shifts, time of break onset, and prior shift duration on total sleep time (TST) between shifts in heavy vehicle drivers (HVDs), and to assess the interaction between break duration and time of break onset. The sleep (actigraphy and sleep diaries) and work shifts (work diaries) of 27 HVDs were monitored during their usual work schedule for up to 9 weeks. Differences in TST between consecutive shifts and days off were assessed. Linear mixed models (followed by pairwise comparisons) assessed whether break duration, prior shift duration, time of break onset, and the interaction between break duration and break onset were related to TST between shifts. Investigators found TST between consecutive shifts (mean [SD] 6.38 [1.38] h) was significantly less than on days off (mean [SD] 7.63 [1.93] h; p < 0.001). Breaks starting between 12:01 and 8:00 a.m. led to shorter sleep (p < 0.05) compared to breaks starting between 4:01 and 8:00 p.m. Break durations up to 7, 9, and 11 h (Australian and European minimum break durations) resulted in a mean (SD) of 4.76 (1.06), 5.66 (0.77), and 6.41 (1.06) h of sleep, respectively. The impact of shift duration prior to the break and the interaction between break duration and time of break were not significant. HVDs' sleep between workdays is influenced independently by break duration and time of break onset. This naturalistic study provides evidence that current break regulations prevent sufficient sleep duration in this industry. Work regulations should evaluate appropriate break durations and break onset times to allow longer sleep opportunities for HVDs. [ABSTRACT FROM AUTHOR]

There are a number of benefits to large‐scale, multi‐site, internationally funded urban research projects if they are operationalized in ways that acknowledge forms of knowledge incommensurability and allow for space to explore the commensurability of different forms of knowledge across different geographies. Such projects are especially important in the context of the precarity of research funding, as such projects can provide the space to explore new urban research avenues that may not have formed core components of the existing urban studies canon and may also bring with them significant and new funding possibilities. In this intervention I use the example of the GCRF‐funded PEAK Urban programme to consider how new urban research questions related to sexuality and health were brought to the fore during the life of the programme, which offer not only new research avenues, but also potential access to significant new funding sources. Programmes such as PEAK Urban therefore have the potential to build the long‐term resilience of urban research. Cutting funding to such programmes may therefore limit the efficacy of the programmes themselves and the long‐term sustainability of urban scholarship. [ABSTRACT FROM AUTHOR]

The inclusion of Men who have Sex with Men (MSM) in global health policies has resulted in significant resource prioritisations in order to treat and prevent the Human Immunodeficiency Virus (HIV)/Acquired Immunodeficiency Syndrome (AIDS). MSM policy inclusions and health prioritisations, however, are primarily motivated by an epidemiological understanding of male same‐sex sexual behaviours, based on biological risks associated with HIV infection. Owing to South Africa's high HIV rates and MSM policy prioritisations, we aimed to examine experiences of engagement in urban MSM‐targeted HIV interventions. Qualitative interviews were conducted with participants (n = 20) who previously engaged in MSM‐HIV interventions, across a variety of historically marginalised "township" spaces in Cape Town, South Africa. Interviews were audio‐recorded with the consent of all participants, transcribed verbatim, and verified, and anonymised using alpha‐numeric codes. Data were analysed for core themes and in this paper we describe interactions between biological and social risks that shape city life for MSM in diverse township spaces. When positioned against the background of the Neuropolis, a recent sociological intervention by Des Fitzgerald, Nikolas Rose and Ilina Singh, our results portray urban life among MSM as a form of biological citizenship: (1) constructed by experiences that are constitutive of biosocial stressors, based on (2) health‐seeking attitudes and behaviours, and (3) reinforced through socio‐spatial engagements in peer‐led and community‐based HIV interventions. We conclude by offering critical insight into recent calls for the development of comprehensive and localised peer‐led health programmes as a current void in the geographies of health and sexualities in the global south. In this paper we describe Men who have Sex with Men and their urban experiences associated with HIV/AIDS interventions, and socio‐economic and spatial health inequalities in "townships" across Cape Town, South Africa. MSM's engagement in HIV interventions was examined as a form of urban citizenship that is: (1) constructed by biological and social interactions, (2) based on health‐seeking attitudes and behaviours, and (3) reinforced through peer‐led socio‐spatial relations. We offer critical insights into recent calls for comprehensive urban interventions in Africa as a current void in the geographies of health and sexualities in the global south. [ABSTRACT FROM AUTHOR]

Under the current African vulture crisis, supplementary feeding sites (SFS), which provide carrion resources, have become a popular conservation tool to address vulture declines. In South Africa, this practice is unregulated and the context in which SFS operate and their adherence to best management practices is currently unknown. In this study, we conducted a survey with SFS managers regarding the management of their SFS to evaluate potential conservation implications of different practices. Half of the SFS surveyed were associated with livestock farming. Overall, most managers (84%) perceived some benefit from running an SFS, largely attributed to cleaning services provided by vultures. Over half of the managers perceived no disadvantages from running SFS. We found a positive correlation between numbers of vultures seen at SFS and the amount of food provided there. Despite unintentional and intentional poisoning being identified by experts as the most critical threats to vultures in Southern Africa, only 47 and 24% of managers, respectively, listed these as potential threats to vultures, highlighting limited understanding of current vulture conservation issues. Most managers (85%) vetted carcasses for provisioning suitability based on whether they had been treated with veterinary drugs, but relatively few managers (10%) did the same for lead (Pb) contamination. Only 30% of managers considered threats to vultures when they decided on a location for their SFS. Overall, this study unveils that at many SFS, safety conditions are not met and vultures may be exposed to risks, such as the ingestion of toxic substances (e.g., Pb) or electrocution by energy infrastructure. To minimize unintended negative consequences from SFS, it will be essential to increase the interaction between SFS managers and conservation practitioners, to increase the flow of information on best management practices and enforce stringent and clear guidelines that minimize any risks to vultures. [ABSTRACT FROM AUTHOR]

Aim In clear, cold-water lakes, ultraviolet radiation ( UV) and temperature are two important stressors that may prevent the establishment of aquatic invasive species by inhibiting the survival of sensitive early life history stages. In this study, we develop a UV-temperature response model to predict the establishment potential of a warmwater fish, largemouth bass ( Micropterus salmoides), in a large subalpine lake based on the ability of bass larvae to tolerate UV and temperature stress along a UV-temperature stress gradient. Location Lake Tahoe ( California/ Nevada, USA). Methods We compared the UV tolerance of largemouth bass larvae to that of the native redside minnow ( Richardsonius egregius) in outdoor UV exposure-response experiments. A UV-temperature response model for larval bass was developed that combined the experimentally derived UV exposure response from our outdoor experiments with a temperature response curve derived from the literature. We used the UV-temperature response model to predict reproductive success (i.e. larval survival) over the range of UV exposure and temperature conditions in nearshore Lake Tahoe. The model predictions were validated with in situ incubation experiments at nearshore locations. Results Non-native bass were significantly less UV tolerant than native redside minnows. The UV-temperature response model predicted that larval bass survival varies seasonally, spatially and over depth gradients in nearshore Lake Tahoe and is constrained by UV and temperature conditions. In situ incubation experiments confirmed model predictions. Main conclusions Our findings provide important insights into the potential for species invasion in clear, cold-water lakes that are experiencing significant changes in both temperature and transparency. The conceptual model and approach that we employ is a potentially powerful tool for exploring unanswered questions in invasion biology, including the role of alternate stable states in facilitating invasion and the potential for invasive species to promote 'invasional meltdown' through their impacts on water clarity and temperature. [ABSTRACT FROM AUTHOR]

Previous studies have demonstrated independent effects of both solar ultraviolet radiation (UV; 280-400 nm) and planktivorous fish on the vertical distribution of Daphnia. We examined the behavioral response of adult and juvenile Daphnia to both UV and planktivorous fish simultaneously in a small temperate lake in eastern Pennsylvania by conducting a large-scale (15 m deep) in situ mesocosm experiment with full factorial treatments (± UV and ± fish). UV induced an avoidance of the surface waters in both juvenile and adult Daphnia. In contrast, the response of Daphnia to fish depended on the presence of UV, with a clear interactive effect. In the presence of both UV and fish, Daphnia were deeper in the water column than they were in the absence of either UV or fish. Sampling of the lake also revealed a rapid upward shift in the depth distribution of both juveniles and adults following a rare and intense early-summer storm that reduced the lake's transparency to both UV (for example, 380 nm UV-A) and photosynthetically active radiation (400-700 nm) by 44% and 39%, respectively. Evidence of a novel benefit to UV avoidance behavior was also observed: surface avoidance of UV reduces the hazards of Daphnia getting caught in the surface air--water interface and perishing. These results highlight the interactive effects of fish and UV on Daphnia vertical distribution under near-natural conditions in situ. [ABSTRACT FROM AUTHOR]

Within Lake Tahoe (CA/NV), USA, multiple environmental stressors are present that can affect both native and nonnative fish species. Stressors include natural ultraviolet radiation (UVR) and polycyclic aromatic hydrocarbons (PAHs). Many PAHs, such as fluoranthene (FLU) are phototoxic to aquatic organisms in the presence of UVR. Decreasing levels of UVR due to eutrophication and increasing levels of PAHs due to recreational activities may combine to affect the relative ability of native versus nonnative fish species to survive in the lake. The objective of the present study was to examine the differential effects of exposure to different levels of UVR and phototoxic FLU in native and nonnative fish species. Responses to these changes in the native Lahontan redside minnow ( Richardsonius egregius) and the nonnative warm-water bluegill sunfish ( Lepomis macrochirus) were compared during toxicity tests, which were conducted in controlled outdoor exposures. Physiological defenses were also investigated in an attempt to elucidate ways each species may tolerate UVR and UVR + FLU exposures. It was determined that the native redside minnow is more tolerant to UVR and UVR + FLU exposure when compared to the nonnative bluegill. In addition, a natural UVR coping mechanism, increased pigmentation, is exhibited to a greater extent in the native redside. The present study will help determine the potential for a future successful invasion of the bluegill and similar species in Lake Tahoe and other oligotrophic, montane lakes that are susceptible to habitat alteration, nutrient inputs, and recreational activity. Environ. Toxicol. Chem. 2012; 31: 1129-1135. © 2012 SETAC [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to investigate the feasibility of increasing the system spatial resolution and scanning speed of Hologic Selenia Dimensions digital breast tomosynthesis (DBT) scanner by replacing the rotating mammography x-ray tube with a specially designed carbon nanotube (CNT) x-ray source array, which generates all the projection images needed for tomosynthesis reconstruction by electronically activating individual x-ray sources without any mechanical motion. The stationary digital breast tomosynthesis (s-DBT) design aims to (i) increase the system spatial resolution by eliminating image blurring due to x-ray tube motion and (ii) reduce the scanning time. Low spatial resolution and long scanning time are the two main technical limitations of current DBT technology. Methods: A CNT x-ray source array was designed and evaluated against a set of targeted system performance parameters. Simulations were performed to determine the maximum anode heat load at the desired focal spot size and to design the electron focusing optics. Field emission current from CNT cathode was measured for an extended period of time to determine the stable life time of CNT cathode for an expected clinical operation scenario. The source array was manufactured, tested, and integrated with a Selenia scanner. An electronic control unit was developed to interface the source array with the detection system and to scan and regulate x-ray beams. The performance of the s-DBT system was evaluated using physical phantoms. Results: The spatially distributed CNT x-ray source array comprised 31 individually addressable x-ray sources covering a 30 angular span with 1 pitch and an isotropic focal spot size of 0.6 mm at full width at half-maximum. Stable operation at 28 kV(peak) anode voltage and 38 mA tube current was demonstrated with extended lifetime and good source-to-source consistency. For the standard imaging protocol of 15 views over 14, 100 mAs dose, and 2 × 2 detector binning, the projection resolution along the scanning direction increased from 4.0 cycles/mm [at 10% modulation-transfer-function (MTF)] in DBT to 5.1 cycles/mm in s-DBT at magnification factor of 1.08. The improvement is more pronounced for faster scanning speeds, wider angular coverage, and smaller detector pixel sizes. The scanning speed depends on the detector, the number of views, and the imaging dose. With 240 ms detector readout time, the s-DBT system scanning time is 6.3 s for a 15-view, 100 mAs scan regardless of the angular coverage. The scanning speed can be reduced to less than 4 s when detectors become faster. Initial phantom studies showed good quality reconstructed images. Conclusions: A prototype s-DBT scanner has been developed and evaluated by retrofitting the Selenia rotating gantry DBT scanner with a spatially distributed CNT x-ray source array. Preliminary results show that it improves system spatial resolution substantially by eliminating image blur due to x-ray focal spot motion. The scanner speed of s-DBT system is independent of angular coverage and can be increased with faster detector without image degration. The accelerated lifetime measurement demonstrated the long term stability of CNT x-ray source array with typical clinical operation lifetime over 3 years. [ABSTRACT FROM AUTHOR]

Predicting where species invasions will occur remains a substantial challenge in ecology, but identifying factors that ultimately constrain the distribution of potential invaders could facilitate successful prediction. Whereas ultraviolet radiation (UVR) is recognized as an important factor controlling species distribution and community composition, the role of UVR in a habitat invasibility context has not been explored. Here we examine how underwater UVR can regulate warm-water fish invasion. In Lake Tahoe, California and Nevada, USA, established populations of exotic bluegill sunfish (Lepomis macrochirus) are currently limited to turbid, low-UVR embayments. An in situ incubation experiment that manipulated incident UVR exposure of larval bluegill, combined with an assessment of UVR exposure levels in nearshore habitats around Lake Tahoe, demonstrates that UVR can mediate habitat invasibility. Our findings suggest that the susceptibility to invasion by UVR sensitive species may increase in transparent aquatic systems threatened by declining water quality, and they highlight the importance of abiotic factors as regulators of invasion risk in ecosystems. [ABSTRACT FROM AUTHOR]

Within and beyond geography, there has been a growing concern in understanding how and why exclusion can occur within ‘gay spaces’, with a specific focus on Western Europe and North America. Heidi Nast's (2002 Queer patriarchies, queer racisms, international Antipode 34 874–909) work on the ‘white queer patriarch’ has taken this work further by exploring the multiple, interrelated, historical and contemporary factors that can lead to exclusion and exploitation. Despite growing interest surrounding South Africa's new liberal queer agenda, issues of contemporary exclusion among queer groups as a direct result of race and racism have remained relatively unexplored. By incorporating elements of Nast's schema, this article will examine the power that exists in the creation and framing of essentialistic ‘white’ and ‘coloured’ queer male subjects in Cape Town's gay village. These subjects will be shown to simultaneously draw on historical inequalities while also re-imagining them in contemporary settings to re-inscribe perceptions of classed and gendered difference. The creation of such inequitable subjects helps us understand how exclusion can become real and normalised within a space such as Cape Town's gay village in a way that draws on a history of material inequalities and discursive perceptions of race. [ABSTRACT FROM AUTHOR]

Purpose: In principle, a stationary digital breast tomosynthesis (s-DBT) system has better image quality when compared to continuous motion DBT systems due to zero motion blur of the source. The authors have developed a s-DBT system by using a linear carbon nanotube x-ray source array. The purpose of the current study was to quantitatively evaluate the performance of the s-DBT system; and investigate the dependence of imaging quality on the system configuration parameters. Methods: Physical phantoms were used to assess the image quality of each configuration including inplane resolution as measured by the modulation transfer function (MTF), inplane contrast as measured by the signal difference to noise ratio (SdNR), and depth resolution as measured by the z-axis artifact spread function. Five parameters were varied to create five groups of configurations: (1) total angular span; (2) total number of projection images; (3) distribution of exposure (mAs) across the projection images; (4) entrance dose; (5) detector pixel size. Results: It was found that the z-axis depth resolution increased with the total angular span but was insensitive to the number of projection images, mAs distribution, entrance dose, and detector pixel size. The SdNR was not affected by the angular span or the number of projection images. A decrease in SdNR was observed when the mAs was not evenly distributed across the projection images. As expected, the SdNR increased with entrance dose and when larger pixel sizes were used. For a given detector pixel size, the inplane resolution was found to be insensitive to the total angular span, number of projection images, mAs distribution, and entrance dose. A 25% increase in the MTF was observed when the detector was operating in full resolution mode (70 μm pixel size) compared to 2 × 2 binned mode (140 μm pixel size). Conclusions: The results suggest that the optimal imaging configuration for a s-DBT system is a large angular span, an intermittent number of projection views, and a uniform mAs distribution over all views. With the detector operating at full resolution, a stationary DBT system can achieve an inplane resolution of 5.1 cycles per mm, which is significantly better than continuous motion DBT systems. [ABSTRACT FROM AUTHOR]