Quantitative determination of pyrethroids, pyrethrins, and piperonyl butoxide in surface water by high-resolution gas chromatography/high-resolution mass spectrometry

A new method for determination of pyrethroids, pyrethrins, and piperonyl butoxide (PBO) by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS) was developed for surface water samples. The method is based on sampling 100 L of ambient surface water with a solid phase extraction (SPE) technique that uses both wound glass fiber filters for collecting the particulate-associated chemicals and XAD-2 resin for collecting the dissolved chemicals. The method detection limits of the analytes ranged from 0.58 to 8.16 ng/sample, which is equivalent to a detection limit range of 0.0058-0.082 ng/L for a 100 L water sample collected by the SPE technique. The SPE when coupled with HRGC/HRMS was a suitable match for detecting these chemicals at subnanogram per liter ranges that are toxicologically significant to aquatic organisms. To confirm the utility of this method for environmental applications, pyrethroids and PBO were found at subnanogram per liter concentrations in surface water samples collected from five tributaries (primarily urban creeks) of the San Francisco Bay, California.     

Antigen-specific proliferation and activation of peripheral blood mononuclear cells from Mycobacterium bovis-infected reindeer

To evaluate antigen-specific proliferative and activation-associated responses from Mycobacterium bovis-infected reindeer, blood mononuclear cells from M. bovis- (n = 10) and non-infected reindeer (n = 4) were stimulated with a recombinant early secretory antigenic target-6 and culture filtrate protein-10 fusion protein (rESAT6:CFP10), M. bovis purified protein derivative, pokeweed mitogen, or medium alone and evaluated by flow cytometry using dye tracker analysis and cell surface marker staining. gammadelta TCR+ and CD8+ cells, but not CD4+ cells, from M. bovis-infected reindeer proliferated in response to specific antigen stimulation. Expression (i.e., mean fluorescence intensity) of CD44 was increased and CD62L decreased on proliferative as compared to non-proliferative fractions in antigen- and mitogen-stimulated cultures. In response rESAT6:CFP10 stimulation, MHC II fluorescence intensity was increased on CD4+, gammadelta TCR+, CD172a+, and IgM+ cells from infected reindeer as compared to that of non-stimulated cells from the same reindeer. Recombinant ESAT6:CFP10 stimulation also induced expansion of a CD172a+, MHC II+ population within mononuclear cell cultures from M. bovis-infected reindeer. Despite a moderate challenge dose and extended duration of incubation, experimental infection of reindeer was generally limited to lymph nodes draining the inoculation site, suggestive of host resistance to progressive disease. Present in vitro findings, therefore, may be predictive of host responses by reindeer that limit progression to disseminated disease.     

Discovery of a young planetary-mass binary

We have identified a companion to the young planetary-mass brown dwarf Oph 162225-240515. This pair forms a resolved binary consisting of two objects with masses comparable to those of extrasolar giant planets. Several lines of evidence confirm the coevality and youth of the two objects, suggesting that they form a physical binary. Models yield masses of approximately 14 and approximately 7 times the mass of Jupiter for the primary and the secondary object, respectively, at an age of approximately 1 million years. A wide ( approximately 240-astronomical unit) binary in the ultra-low-mass regime poses a challenge to some popular models of brown dwarf formation.     

Adsorption, transport and degradation of fipronil termiticide in three Hawaii soils

BACKGROUND: The behavior of the termiticide fipronil in soils was studied to assess its potential to contaminate ground and surface water. This study characterizes (1) adsorption of fipronil in three different soils, (2) transport of fipronil through leaching and runoff under simulated rainfall in these soils and (3) degradation of fipronil to fipronil sulfide and fipronil sulfone in these soils. RESULTS: The adsorption experiments showed a Freundlich isotherm for fipronil with K_oc equal to 1184 L kg^?1. In the leaching experiments, the concentration of fipronil and its metabolites in leachate and runoff decreased asymptotically with time. The concentration of fipronil in the leachate from the three soils correlated inversely with soil organic carbon content. The degradation experiment showed that the half‐life of fipronil in the soils ranged from 28 to 34 days when soil moisture content was 75% of field capacities, and that 10.7–23.5% of the degraded fipronil was transformed into the two metabolites (fipronil sulfide and fipronil sulfone). CONCLUSION: Fipronil showed large losses through leaching but small losses via runoff owing to low volumes of runoff water generated and/or negligible particle‐facilitated transport of fipronil. The half‐life values of fipronil in all three soils were similar. Copyright © 2011 Society of Chemical Industry     

Ethnicity and conflict: theory and facts

Over the second half of the 20th century, conflicts within national boundaries became increasingly dominant. One-third of all countries experienced civil conflict. Many (if not most) such conflicts involved violence along ethnic lines. On the basis of recent theoretical and empirical research, we provide evidence that preexisting ethnic divisions do influence social conflict. Our analysis also points to particular channels of influence. Specifically, we show that two different measures of ethnic division--polarization and fractionalization--jointly influence conflict, the former more so when the winners enjoy a "public" prize (such as political power or religious hegemony), the latter more so when the prize is "private" (such as looted resources, government subsidies, or infrastructures). The available data appear to strongly support existing theories of intergroup conflict. Our argument also provides indirect evidence that ethnic conflicts are likely to be instrumental, rather than driven by primordial hatreds.     

Deltamethrin and cypermethrin resistance status of Rhipicephalus (Boophilus) microplus collected from six agro-climatic regions of India

A cross sectional study was conducted to assess the prevalence of synthetic pyrethroids (SP) resistance in Rhipicephalus (Boophilus) microplus in India. Twenty-seven areas located in six agro-climatic regions were selected for the collection of engorged ticks using two stage stratified sampling procedure. Adult immersion test (AIT) and larval packet test (LPT) were optimized using laboratory reared susceptible line of R.(B.) microplus (IVRI-I) for determination of 95% lethal concentration (LC(95)) of deltamethrin (29.6 ppm in AIT and 35.5 ppm in LPT) and cypermethrin (349.1 ppm in AIT and 350.7 ppm in LPT). The AIT with a discriminating dose (2 × LC(95)) was used to detect deltamethrin and cypermethrin resistance in the field isolates of R.(B.) microplus. On the basis of the data generated on three variables viz., mortality, egg masses and reproductive index, the resistance level was categorized as I, II, III and IV. The overall prevalence of SP-resistant R.(B.) microplus among the sampled farms was 66.6% (18/27). Out of these 18 areas, resistance to deltamethrin at level I was detected in 08 areas (resistance factor=2.0-4.9), at level II in 09 areas (RF=5.2-11.8), at level III in 01 area (RF=34.9) and at level IV in 01 area (RF=95.7). The resistance to cypermethrin was detected in 16 areas and level of resistance was detected at level I in 10 areas (RF=2.06-4.64) and at level II in 06 areas (RF=5.13-9.88). The middle-gangetic and trans-gangetic plains revealed higher density of resistant ticks where intensive cross bred cattle population are reared and the SP compounds are commonly used. The data generated on acaricide resistant status in ticks will help in formulating tick control strategy for the country.     

Modeling carbon allocation in trees: a search for principles

We review approaches to predicting carbon and nitrogen allocation in forest models in terms of their underlying assumptions and their resulting strengths and limitations. Empirical and allometric methods are easily developed and computationally efficient, but lack the power of evolution-based approaches to explain and predict multifaceted effects of environmental variability and climate change. In evolution-based methods, allocation is usually determined by maximization of a fitness proxy, either in a fixed environment, which we call optimal response (OR) models, or including the feedback of an individual's strategy on its environment (game-theoretical optimization, GTO). Optimal response models can predict allocation in single trees and stands when there is significant competition only for one resource. Game-theoretical optimization can be used to account for additional dimensions of competition, e.g., when strong root competition boosts root allocation at the expense of wood production. However, we demonstrate that an OR model predicts similar allocation to a GTO model under the root-competitive conditions reported in free-air carbon dioxide enrichment (FACE) experiments. The most evolutionarily realistic approach is adaptive dynamics (AD) where the allocation strategy arises from eco-evolutionary dynamics of populations instead of a fitness proxy. We also discuss emerging entropy-based approaches that offer an alternative thermodynamic perspective on allocation, in which fitness proxies are replaced by entropy or entropy production. To help develop allocation models further, the value of wide-ranging datasets, such as FLUXNET, could be greatly enhanced by ancillary measurements of driving variables, such as water and soil nitrogen availability.