Dzuds, droughts, and livestock mortality in Mongolia

Recent incidences of mass livestock mortality, known as dzud, have called into question the sustainability of pastoral nomadic herding, the cornerstone of Mongolian culture. A total of 20 million head of livestock perished in the mortality events of 2000–2002, and 2009–2010. To mitigate the effects of such events on the lives of herders, international agencies such as the World Bank are taking increasing interest in developing tailored market-based solutions like index-insurance. Their ultimate success depends on understanding the historical context and underlying causes of mortality. In this paper we examine mortality in 21 Mongolian aimags (provinces) between 1955 and 2013 in order to explain its density independent cause(s) related to climate variability. We show that livestock mortality is most strongly linked to winter (November–February) temperatures, with incidences of mass mortality being most likely to occur because of an anomalously cold winter. Additionally, we find prior summer (July–September) drought and precipitation deficit to be important triggers for mortality that intensifies the effect of upcoming winter temperatures on livestock. Our density independent mortality model based on winter temperature, summer drought, summer precipitation, and summer potential evaporanspiration explains 48.4% of the total variability in the mortality dataset. The Mongolian index based livestock insurance program uses a threshold of 6% mortality to trigger payouts. We find that on average for Mongolia, the probability of exceedance of 6% mortality in any given year is 26% over the 59 year period between 1955 and 2013

Energy-Loss mechanisms of a low-discharge-voltage hall thruster

The findings of the probe study and thrust stand measurements performed on an Aerojet BPT-2000 Hall thruster at discharge voltage from 100 to 300 V for 3 to 5 mg/s flow of xenon were examined. Voltage utilization efficiencies were obtained by a four-grid retarding potential analyzer (RPA) probe placed 0.55m downstream from the thruster faceplate at 0.15, and 30° to the thruster centerline. The Faraday probe was enclosed in an alumina sheath with an outer diameter of 4.75 mm. Energy efficiency can further be separated into voltage utilization efficiency and current efficiency, where the voltage utilization efficiency is the percentage of the anode-cathode potential that the ions are accelerated through and the current efficiency is the ratio of exhausted current to discharge current. The results showed that current levels were nearly constant for each mass-flow rate until the discharge voltage dropped below 200V, where the current increased rapidly

Incorporating Measures of Community in Wildland Fire Preparedness Education

Using data from a survey of Colorado residents, we examined measures of sense of community (SOC). Respondents were asked to rate fifteen items measuring SOC on a 7-point scale, where 1 = strongly disagree and 7 = strongly agree. McMillan and Chavis (1986) suggest that these items form four dimensions of SOC: membership, influence, reinforcement of needs, and shared emotional connection. The four dimensions of SOC were supported by the data (i.e., Cronbach’s alpha \u3e .80 for all four dimensions). A cluster analysis of the four dimensions of SOC identified three distinct segments of individuals. The first cluster indicated that they felt a strong SOC on all four dimensions. The second cluster felt a more neutral SOC, while the third cluster felt a low SOC on all four dimensions. We hypothesize that individuals with a low SOC will not be as likely to adopt wildfire protection (i.e., defensible space) behaviors. Understanding these segments can help inform future wildland fire educational materials

Efficiency analysis of a low discharge voltage Hall thruster

Power loss mechanisms for a 2 kW (nominal) Hall thruster operating at low discharge voltages were examined through thrust stand measurements and probe studies. Operating conditions included discharge voltages ranging from 100 V to 300 V and mass flow rates of 3 to 5 mg/s of xenon. Thrust stand measurements indicate a minimum thrust efficiency of 15% at 100 V at 3 mg/s and a maximum of 59% at 300 V and 5 mg/s. Retarding potential analyzer, emissive and Faraday probes were utilized to quantify multiple sources of inefficiency. The ratio of exhausted ion current to discharge current was found to be the dominant loss mechanism at low discharge voltage

Climate Forcing and Salinity Variability in Chesapeake Bay, USA

Salinity is a critical factor in understanding and predicting physical and biogeochemical processes in the coastal ocean where it varies considerably in time and space. In this paper, we introduce a Chesapeake Bay community implementation of the Regional Ocean Modeling System (ChesROMS) and use it to investigate the interannual variability of salinity in Chesapeake Bay. The ChesROMS implementation was evaluated by quantitatively comparing the model solutions with the observed variations in the Bay for a 15-year period (1991 to 2005). Temperature fields were most consistently well predicted, with a correlation of 0.99 and a root mean square error (RMSE) of 1.5 degrees C for the period, with modeled salinity following closely with a correlation of 0.94 and RMSE of 2.5. Variability of salinity anomalies from climatology based on modeled salinity was examined using empirical orthogonal function analysis, which indicates the salinity distribution in the Bay is principally driven by river forcing. Wind forcing and tidal mixing were also important factors in determining the salinity stratification in the water column, especially during low flow conditions. The fairly strong correlation between river discharge anomaly in this region and the Pacific Decadal Oscillation suggests that the long-term salinity variability in the Bay is affected by large-scale climate patterns. The detailed analyses of the role and importance of different forcing, including river runoff, atmospheric fluxes, and open ocean boundary conditions, are discussed in the context of the observed and modeled interannual variability

Mechanical Unloading Promotes Myocardial Energy Recovery in Human Heart Failure

BACKGROUND: Impaired bioenergetics is a prominent feature of the failing heart, but the underlying metabolic perturbations are poorly understood. METHODS AND RESULTS: We compared metabolomic, gene transcript, and protein data from six paired failing human left ventricular (LV) tissue samples obtained during left ventricular assist device (LVAD) insertion (heart failure (HF) samples) and at heart transplant (post-LVAD samples). Non-failing left ventricular (NFLV) wall samples procured from explanted hearts of patients with right HF served as novel comparison samples. Metabolomic analyses uncovered a distinct pattern in HF tissue: 2.6 fold increased pyruvate concentrations coupled with reduced Krebs cycle intermediates and short-chain acylcarnitines, suggesting a global reduction in substrate oxidation. These findings were associated with decreased transcript levels for enzymes that catalyze fatty acid oxidation and pyruvate metabolism and for key transcriptional regulators of mitochondrial metabolism and biogenesis, peroxisome proliferator-activated receptor gamma co-activator1α (PGC1A, 1.3 fold) and estrogen-related receptor α (ERRA, 1.2 fold) and γ (ERRG, 2.2 fold). Thus, parallel decreases in key transcription factors and their target metabolic enzyme genes can explain the decreases in associated metabolic intermediates. Mechanical support with LVAD improved all of these metabolic and transcriptional defects. CONCLUSIONS: These observations underscore an important pathophysiologic role for severely defective metabolism in HF, while the reversibility of these defects by LVAD suggests metabolic resilience of the human heart