Six hundred years of South American tree rings reveal an increase in severe hydroclimatic events since mid-20th century.

South American (SA) societies are highly vulnerable to droughts and pluvials, but lack of long-term climate observations severely limits our understanding of the global processes driving climatic variability in the region. The number and quality of SA climate-sensitive tree ring chronologies have significantly increased in recent decades, now providing a robust network of 286 records for characterizing hydroclimate variability since 1400 CE. We combine this network with a self-calibrated Palmer Drought Severity Index (scPDSI) dataset to derive the South American Drought Atlas (SADA) over the continent south of 12°S. The gridded annual reconstruction of austral summer scPDSI is the most spatially complete estimate of SA hydroclimate to date, and well matches past historical dry/wet events. Relating the SADA to the Australia-New Zealand Drought Atlas, sea surface temperatures and atmospheric pressure fields, we determine that the El Niño-Southern Oscillation (ENSO) and the Southern Annular Mode (SAM) are strongly associated with spatially extended droughts and pluvials over the SADA domain during the past several centuries. SADA also exhibits more extended severe droughts and extreme pluvials since the mid-20th century. Extensive droughts are consistent with the observed 20th-century trend toward positive SAM anomalies concomitant with the weakening of midlatitude Westerlies, while low-level moisture transport intensified by global warming has favored extreme rainfall across the subtropics. The SADA thus provides a long-term context for observed hydroclimatic changes and for 21st-century Intergovernmental Panel on Climate Change (IPCC) projections that suggest SA will experience more frequent/severe droughts and rainfall events as a consequence of increasing greenhouse gas emissions.

No increase in global temperature variability despite changing regional patterns.

Evidence from Greenland ice cores shows that year-to-year temperature variability was probably higher in some past cold periods, but there is considerable interest in determining whether global warming is increasing climate variability at present. This interest is motivated by an understanding that increased variability and resulting extreme weather conditions may be more difficult for society to adapt to than altered mean conditions. So far, however, in spite of suggestions of increased variability, there is considerable uncertainty as to whether it is occurring. Here we show that although fluctuations in annual temperature have indeed shown substantial geographical variation over the past few decades, the time-evolving standard deviation of globally averaged temperature anomalies has been stable. A feature of the changes has been a tendency for many regions of low variability to experience increases, which might contribute to the perception of increased climate volatility. The normalization of temperature anomalies creates the impression of larger relative overall increases, but our use of absolute values, which we argue is a more appropriate approach, reveals little change. Regionally, greater year-to-year changes recently occurred in much of North America and Europe. Many climate models predict that total variability will ultimately decrease under high greenhouse gas concentrations, possibly associated with reductions in sea-ice cover. Our findings contradict the view that a warming world will automatically be one of more overall climatic variation.

Exploring examiner judgement of professional competence in rater based assessment.

Exercise physiology courses have transitioned to competency based, forcing Universities to rethink assessment to ensure students are competent to practice. This study built on earlier research to explore rater cognition, capturing factors that contribute to assessor decision making about students' competency. The aims were to determine the source of variation in the examination process and document the factors impacting on examiner judgment. Examiner judgement was explored from both a quantitative and qualitative perspective. Twenty-three examiners viewed three video encounters of student performance on an OSCE. Once rated, analysis of variance was performed to determine where the variance was attributed. A semi-structured interview drew out the examiners reasoning behind their ratings. Results highlighted variability of the process of observation, judgement and rating, with each examiner viewing student performance from different lenses. However, at a global level, analysis of variance indicated that the examiner had a minimal impact on the variance, with the majority of variance explained by the student performance on task. One anomaly noted was in the assessment of technical competency, whereby the examiner had a large impact on the rating, linked to assessing according to curriculum content. The thought processes behind judgement were diverse and if the qualitative results had been used in isolation, may have led to the researchers drawing conclusions that the examined performances would have yielded widely different ratings. However, as a cohort, the examiners were able to distinguish good and poor levels of competency with the majority of student competency linked to the varying ability of the student.

Peer learning in the UNSW Medicine program.

BACKGROUND: The UNSW Australia Medicine program explicitly structures peer learning in program wide mixing of students where students from two adjoining cohorts complete the same course together, including all learning activities and assessment. The purpose of this evaluation is to explore the student experience of peer learning and determine benefits and concerns for junior and senior students. METHODS: All medical students at UNSW Australia in 2012 (n = 1608) were invited to complete the Peer Learning Questionnaire consisting of 26 fixed-response items and 2 open-ended items exploring vertical integration and near-peer teaching. Assessment data from vertically integrated and non-vertically integrated courses were compared for the period 2011-2013. RESULTS: We received valid responses from 20 % of medical students (n = 328). Eighty percent of respondents were positive about their experience of vertical integration. Year 1 students reported that second year students provided guidance and reassurance (87.8 %), whilst year 2 students reported that the senior role helped them to improve their own understanding, communication and confidence (84 %). Vertical integration had little effect on examination performance and failure rates. CONCLUSIONS: This evaluation demonstrates that vertical integration of students who are one year apart and completing the same course leads to positive outcomes for the student experience of learning. Students benefit through deeper learning and the development of leadership qualities within teams. These results are relevant not only for medical education, but also for other professional higher education programs.

Improving the transition from medical school to internship - evaluation of a preparation for internship course.

BACKGROUND: This study evaluates the impact of a new 'Preparation for Internship' (PRINT) course, which was developed to facilitate the transition of University of New South Wales (UNSW) medical graduates from Medical School to Internship. METHODS: During a period of major curricular reform, the 2007 (old program) and 2009 (new program) cohorts of UNSW final year students completed the Clinical Capability Questionnaire (CCQ) prior to and after undertaking the PRINT course. Clinical supervisors' ratings and self-ratings of UNSW 2009 medical graduates were obtained from the Hospital-based Prevocational Progress Review Form. RESULTS: Prior to PRINT, students from both cohorts perceived they had good clinical skills, with lower ratings for capability in procedural skills, operational management, and administrative tasks. After completing PRINT, students from both cohorts perceived significant improvement in their capability in procedural skills, operational management, and administrative tasks. Although PRINT also improved student-perceived capability in confidence, interpersonal skills and collaboration in both cohorts, curriculum reform to a new outcomes-based program was far more influential in improving self-perceptions in these facets of preparedness for hospital practice than PRINT. CONCLUSIONS: The PRINT course was most effective in improving students' perceptions of their capability in procedural skills, operational management and administrative tasks, indicating that student-to-intern transition courses should be clinically orientated, address relevant skills, use experiential learning, and focus on practical tasks. Other aspects that are important in preparation of medical students for hospital practice cannot be addressed in a PRINT course, but major improvements are achievable by program-wide curriculum reform.

Predictive validity of a new integrated selection process for medical school admission.

BACKGROUND: This paper is an evaluation of an integrated selection process utilising previous academic achievement [Universities Admission Index (UAI)], a skills test [Undergraduate Medicine and Health Sciences Admission Test (UMAT)], and a structured interview, introduced (in its entirety) in 2004 as part of curriculum reform of the undergraduate Medicine Program at the University of New South Wales (UNSW), Australia. Demographic measures of gender, country of birth, educational background and rurality are considered. METHOD: Admission scores and program outcomes of 318 students enrolled in 2004 and 2005 were studied. Regression analyses were undertaken to determine whether selection scores predicted overall, knowledge-based and clinical-based learning outcomes after controlling for demographics. RESULTS: UAI attained the highest values in predicting overall and knowledge-based outcomes. The communication dimension of the interview achieved similar predictive values as UAI for clinical-based outcomes, although predictive values were relatively low. The UMAT did not predict any performance outcome. Female gender, European/European-derived country of birth and non-rurality were significant predictors independent of UAI scores. CONCLUSION: Results indicate promising validity for an integrated selection process introduced for the Medicine Program at UNSW, with UAI and interview predictive of learning outcomes. Although not predictive, UMAT may have other useful roles in an integrated selection process. Further longitudinal research is proposed to monitor and improve the validity of the integrated student selection process.

Attribution of observed surface humidity changes to human influence.

Water vapour is the most important contributor to the natural greenhouse effect, and the amount of water vapour in the atmosphere is expected to increase under conditions of greenhouse-gas-induced warming, leading to a significant feedback on anthropogenic climate change. Theoretical and modelling studies predict that relative humidity will remain approximately constant at the global scale as the climate warms, leading to an increase in specific humidity. Although significant increases in surface specific humidity have been identified in several regions, and on the global scale in non-homogenized data, it has not been shown whether these changes are due to natural or human influences on climate. Here we use a new quality-controlled and homogenized gridded observational data set of surface humidity, with output from a coupled climate model, to identify and explore the causes of changes in surface specific humidity over the late twentieth century. We identify a significant global-scale increase in surface specific humidity that is attributable mainly to human influence. Specific humidity is found to have increased in response to rising temperatures, with relative humidity remaining approximately constant. These changes may have important implications, because atmospheric humidity is a key variable in determining the geographical distribution and maximum intensity of precipitation, the potential maximum intensity of tropical cyclones, and human heat stress, and has important effects on the biosphere and surface hydrology.

Clinical capabilities of graduates of an outcomes-based integrated medical program.

BACKGROUND: The University of New South Wales (UNSW) Faculty of Medicine replaced its old content-based curriculum with an innovative new 6-year undergraduate entry outcomes-based integrated program in 2004. This paper is an initial evaluation of the perceived and assessed clinical capabilities of recent graduates of the new outcomes-based integrated medical program compared to benchmarks from traditional content-based or process-based programs. METHOD: Self-perceived capability in a range of clinical tasks and assessment of medical education as preparation for hospital practice were evaluated in recent graduates after 3 months working as junior doctors. Responses of the 2009 graduates of the UNSW's new outcomes-based integrated medical education program were compared to those of the 2007 graduates of UNSW's previous content-based program, to published data from other Australian medical schools, and to hospital-based supervisor evaluations of their clinical competence. RESULTS: Three months into internship, graduates from UNSW's new outcomes-based integrated program rated themselves to have good clinical and procedural skills, with ratings that indicated significantly greater capability than graduates of the previous UNSW content-based program. New program graduates rated themselves significantly more prepared for hospital practice in the confidence (reflective practice), prevention (social aspects of health), interpersonal skills (communication), and collaboration (teamwork) subscales than old program students, and significantly better or equivalent to published benchmarks of graduates from other Australian medical schools. Clinical supervisors rated new program graduates highly capable for teamwork, reflective practice and communication. CONCLUSIONS: Medical students from an outcomes-based integrated program graduate with excellent self-rated and supervisor-evaluated capabilities in a range of clinically-relevant outcomes. The program-wide curriculum reform at UNSW has had a major impact in developing capabilities in new graduates that are important for 21st century medical practice.

Dexmedetomidine prolongs the duration of action of mepivacaine on anesthesia of the palmar digital nerves of horses.

OBJECTIVE: To determine whether palmar digital nerve (PDN) blockade in horses with a combination of dexmedetomidine and mepivacaine would block the response to mechanical force applied to the digit longer than would anesthetizing these nerves with mepivacaine alone or dexmedetomidine alone. ANIMALS: 8 mares with no signs of lameness. PROCEDURES: In a randomized, crossover, blinded, experimental study, both PDNs of the same forelimb of each horse were anesthetized by perineural injection with either 30 mg mepivacaine alone, 250 µg of dexmedetomidine alone, or 30 mg mepivacaine combined with 250 µg of dexmedetomidine. Each horse received each treatment, and treatments were administered ≥ 2 weeks apart. The mechanical nociceptive threshold was measured at a region between the heel bulbs with the use of a digital force gauge before (baseline) and at 15-minute intervals after treatment. RESULTS: The mean duration of sensory blockade of the digit was 2-fold longer when a combination of mepivacaine and dexmedetomidine was administered (371 minutes), compared with when mepivacaine alone was administered (186 minutes). Treatment with dexmedetomidine alone did not change the mechanical nociceptive threshold substantially from baseline and resulted in no clinical signs of sedation. CLINICAL RELEVANCE: Results indicated that relief from digital pain provided by perineural treatment with mepivacaine for PDN blockade can be extended by adding dexmedetomidine to the injectate.

CO2, the greenhouse effect and global warming: from the pioneering work of Arrhenius and Callendar to today's Earth System Models.

Climate warming during the course of the twenty-first century is projected to be between 1.0 and 3.7°C depending on future greenhouse gas emissions, based on the ensemble-mean results of state-of-the-art Earth System Models (ESMs). Just how reliable are these projections, given the complexity of the climate system? The early history of climate research provides insight into the understanding and science needed to answer this question. We examine the mathematical quantifications of planetary energy budget developed by Svante Arrhenius (1859-1927) and Guy Stewart Callendar (1898-1964) and construct an empirical approximation of the latter, which we show to be successful at retrospectively predicting global warming over the course of the twentieth century. This approximation is then used to calculate warming in response to increasing atmospheric greenhouse gases during the twenty-first century, projecting a temperature increase at the lower bound of results generated by an ensemble of ESMs (as presented in the latest assessment by the Intergovernmental Panel on Climate Change). This result can be interpreted as follows. The climate system is conceptually complex but has at its heart the physical laws of radiative transfer. This basic, or "core" physics is relatively straightforward to compute mathematically, as exemplified by Callendar's calculations, leading to quantitatively robust projections of baseline warming. The ESMs include not only the physical core but also climate feedbacks that introduce uncertainty into the projections in terms of magnitude, but not sign: positive (amplification of warming). As such, the projections of end-of-century global warming by ESMs are fundamentally trustworthy: quantitatively robust baseline warming based on the well-understood physics of radiative transfer, with extra warming due to climate feedbacks. These projections thus provide a compelling case that global climate will continue to undergo significant warming in response to ongoing emissions of CO2 and other greenhouse gases to the atmosphere.

Transdiaphragmatic transport of tracer albumin from peritoneal to pleural liquid measured in rats.

In conscious Wistar-Kyoto rats, we studied the uptake of radioactive tracer (125)I-albumin into the pleural space and circulation after intraperitoneal (IP) injections with 1 or 5 ml of Ringer solution (3 g/dl albumin). Postmortem, we sampled pleural liquid, peritoneal liquid, and blood plasma 2-48 h after IP injection and measured their radioactivity and protein concentration. Tracer concentration was greater in pleural liquid than in plasma approximately 3 h after injection with both IP injection volumes. This behavior indicated transport of tracer through the diaphragm into the pleural space. A dynamic analysis of the tracer uptake with 5-ml IP injections showed that at least 50% of the total pleural flow was via the diaphragm. A similar estimate was derived from an analysis of total protein concentrations. Both estimates were based on restricted pleural capillary filtration and unrestricted transdiaphragmatic transport. The 5-ml IP injections did not change plasma protein concentration but increased pleural and peritoneal protein concentrations from control values by 22 and 30%, respectively. These changes were consistent with a small (approximately 8%) increase in capillary filtration and a small (approximately 20%) reduction in transdiaphragmatic flow from control values, consistent with the small (3%) decrease in hydration measured in diaphragm muscle. Thus the pleural uptake of tracer via the diaphragm with the IP injections occurred by the near-normal transport of liquid and protein.

Natural history of Sin Nombre virus infection in deer mice in urban parks in Oregon.

Sin Nombre virus (SNV), one of at least 45 hantaviruses described worldwide, is hosted by the deer mouse, Peromyscus maniculatus, a common species throughout most of North America. Herein, we describe general life-history characteristics of deer mice and the ways in which these factors relate to the incidence of SNV infections among populations of this host species in and around Portland, Oregon. In total, 3,175 deer mice were captured from October 2002 to September 2005. Transmission of SNV appears to be associated with male breeding behaviors, as more males and adults were infected than expected by capture rate; spring and summer had the highest infection prevalence, as well as scrotal male captures. Wounding rates between infected and uninfected deer mice were not different in any age or sex class. Capture rates were significantly and positively related to the interaction of temperature departure from normal, total precipitation, and number of clear days from two seasons previous (P=0.029), while infection prevalence was significantly and negatively related to the capture rate of juveniles from two seasons previous (P=0.029).

A tale of two toes.

Percutaneous closure of a patent foramen ovale (PFO) is increasingly being performed for patients with suspected paradoxical embolus. We report a rare case of a PFO occluder device related infective endocarditis.