Charge separation instability in an unmagnetized disk plasma around a Kerr black hole

In almost all of plasma theories for astrophysical objects, we have assumed the charge quasi-neutrality of unmagnetized plasmas in global scales. This assumption has been justified because if there is a charged plasma, it induces electric field which attracts the opposite charge, and this opposite charge reduces the charge separation. Here, we report a newly discovered instability which causes a charge separation in a rotating plasma inside of an innermost stable circular orbit (ISCO) around a black hole. The growth rate of the instability is smaller than that of the disk instability even in the unstable disk region and is forbidden in the stable disk region outside of the ISCO. However, this growth rate becomes comparable to that of the disk instability when the plasma density is much lower than a critical density inside of the ISCO. In such case, the charge separation instability would become apparent and cause the charged accretion into the black hole, thus charge the hole up.Comment: 15pages, 1 figur

Effects of a series of triorganotins on ATP levels in human natural killer cells

Natural killer (NK) cells are our initial immune defense against viral infections and cancer development. Thus, agents that are able to interfere with their function increase the risk of cancer and/or infection. A series of triorganotins (trimethyltin (TMT), dimethylphenyltin (DMPT), methyldiphenyltin (MDPT), and triphenyltin (TPT)) have been shown to decrease the lytic function of human NK cells. TPT and MDPT were much more effective than DMPT or TMT at reducing lytic function. This study investigates the role that decreased ATP levels may play in decreases in the lytic function of NK cells induced by these organotins (OTs). A 24h exposure to as high as 10μM TMT caused no decrease in ATP levels even though this level of TMT caused a greater than 75% loss of lytic function. TPT at 200nM caused a decrease in ATP levels of about 20% while decreasing lytic function by greater than 85%. There was no association between ATP levels and lytic function for any of the compounds when NK cells were exposed for 1 or 24h. However, after a 48h exposure to both DMPT and TPT decreased lytic function was associated with decreased ATP levels. There was an association between decreased lytic function and decreased ATP levels after a 6-day exposure to each of the four compounds. These studies indicate that the loss of lytic function seen after 1 and 24h exposures to this series of organotins cannot be accounted for by decreases in ATP. However, after longer exposures loss of lytic function may be in part be attributable to inadequate ATP levels

Powered attendant-propelled wheelchair with assist-as-needed control based on individual physical capabilities

This paper discussed if a powered attendant propelled wheelchairs (PAPW) with assist-as-needed control reduces energy consumption and maximise attendant's physical activity in powered system use. This study introduced a PAPW with force velocity assist control (FVAC) based on individual capability of pushing force velocity relationship. This PAPW assists attendant pushing when more pushing force is needed over usual range of individual physical capabilities of pushing. With the PAPW, we investigated the performance of the FVAC and compared it with proportional assist control (PAC) on a flat level surface and a longitudinal slope (6.5%) with three participants. The experimental results showed that the PAPW with the FVAC reduced 50% of pushing force on the slope and this was similar performance of the PAC in terms of assisting. The FVAC also reduced 79% of mean mechanical assisting power on the flat against the PAC. These results support that the PAPW with the FVAC has flexibilities to adapt to individual physical capabilities and provides certain level of physical activities with sufficient assisting when needed, and low energy consumption for long time and distance operations for attendants

The Lore of Low Methane Livestock:Co-Producing Technology and Animals for Reduced Climate Change Impact

Methane emissions from sheep and cattle production have gained increasing profile in the context of climate change. Policy and scientific research communities have suggested a number of technological approaches to mitigate these emissions. This paper uses the concept of co-production as an analytical framework to understand farmers’ evaluation of a 'good animal’. It examines how technology and sheep and beef cattle are co-produced in the context of concerns about the climate change impact of methane. Drawing on 42 semi-structured interviews, this paper demonstrates that methane emissions are viewed as a natural and integral part of sheep and beef cattle by farmers, rather than as a pollutant. Sheep and beef cattle farmers in the UK are found to be an extremely heterogeneous group that need to be understood in their specific social, environmental and consumer contexts. Some are more amenable to appropriating methane reducing measures than others, but largely because animals are already co-constructed from the natural and the technical for reasons of increased production efficiency

Gamma-ray Emission from an Outer-Gap Accelerator: Constraints on Magnetospheric Current, Magnetic Inclination, and Distance for PSR B1055-52

We investigate a stationary pair production cascade in the outer magnetosphere of a spinning neutron star. The charge depletion due to global flows of charged particles, causes a large electric field along the magnetic field lines. Migratory electrons and/or positrons are accelerated by this field to radiate curvature gamma-rays, some of which collide with the X-rays to materialize as pairs in the gap. The replenished charges partially screen the electric field, which is self-consistently solved, together with the distribution functions of particles and gamma-rays. By solving the Vlasov equations describing this pair production cascade, we demonstrate the existence of a stationary gap in the outer magnetosphere of PSR B1055-52 for a wide range of current densities flowing in the accelerator: From sub to super Goldreich-Julian values. However, we find that the expected GeV spectrum becomes very soft if the current density exceeds the Goldreich-Julian value. We also demonstrate that the GeV spectrum softens with decreasing magnetic inclination and with increasing distance to this pulsar. We thus conclude that a sub-Goldreich-Julian current, a large magnetic inclination, and a small distance (500 pc, say) are plausible to account for EGRET observations. Furthermore, it is found that the TeV flux due to inverse Compton scatterings of infrared photons whose spectrum is inferred from the Rayleigh-Jeans side of the soft blackbody spectrum is much less than the observational upper limit.Comment: 16 pages, 13 figures, ApJ in pres

Generalized four-point characterization method for resistive and capacitive contacts

In this paper, a four-point characterization method is developed for resistive samples connected to either resistive or capacitive contacts. Provided the circuit equivalent of the complete measurement system is known including coaxial cable and connector capacitances as well as source output and amplifier input impedances, a frequency range and capacitive scaling factor can be determined, whereby four-point characterization can be performed. The technique is demonstrated with a discrete element test sample over a wide frequency range using lock-in measurement techniques from 1 Hz - 100 kHz. The data fit well with a circuit simulation of the entire measurement system. A high impedance preamplifier input stage gives best results, since lock-in input impedances may differ from manufacturer specifications. The analysis presented here establishes the utility of capacitive contacts for four-point characterizations at low frequency.Comment: 21 pages, 10 figure

Earth Radiation Budget Experiment (ERBE) scanner instrument anomaly investigation

The results of an ad-hoc committee investigation of in-Earth orbit operational anomalies noted on two identical Earth Radiation Budget Experiment (ERBE) Scanner instruments on two different spacecraft busses is presented. The anomalies are attributed to the bearings and the lubrication scheme for the bearings. A detailed discussion of the pertinent instrument operations, the approach of the investigation team and the current status of the instruments now in Earth orbit is included. The team considered operational changes for these instruments, rework possibilities for the one instrument which is waiting to be launched, and preferable lubrication considerations for specific space operational requirements similar to those for the ERBE scanner bearings

'Open Marxism' against and beyond the 'Great Enclosure'? Reflections on How (Not) to Crack Capitalism

The main purpose of this article is to provide an in-depth discussion of John Holloway’s recent book, Crack Capitalism. To this end, the paper offers a detailed account of the key strengths and weaknesses of Holloway’s version of ‘open Marxism’. The analysis is divided into two parts. The first part focuses on six significant strengths of Crack Capitalism: (1) its insistence upon the importance of autonomous forms of agenda-setting for both individual and collective emancipation; (2) its emphasis on the ordinary constitution of social struggles; (3) its fine-grained interpretation of the socio-ontological conditions underlying human agency; (4) its processual conception of radical social transformation; (5) its recognition of the elastic, adaptable, and integrative power of capitalism; and (6) its proposal for an alternative critical theory, commonly known as ‘open Marxism’ or ‘autonomous Marxism’. The second part of the study examines the principal weaknesses of Crack Capitalism: (1) the counterproductive implications of the preponderance of negativity, owing to a one-sided concern with critique, cracks, and crises; (2) conceptual vagueness; (3) an overuse of poetic and metaphorical language; (4) the absence of a serious engagement with the question of normativity; (5) a lack of substantive evidence; (6) a residual economic reductionism; (7) a simplistic notion of gender; (8) the continuing presence of various problematic ‘isms’; (9) the misleading distinction between ‘doing’ and ‘labour’; (10) a reductive understanding of capitalism; (11) an unrealistic view of society; and (12) socio-ontological idealis

Robotic milking technologies and renegotiating situated ethical relationships on UK dairy farms

Robotic or automatic milking systems (AMS) are novel technologies that take over the labor of dairy farming and reduce the need for human-animal interactions. Because robotic milking involves the replacement of 'conventional' twice-a-day milking managed by people with a system that supposedly allows cows the freedom to be milked automatically whenever they choose, some claim robotic milking has health and welfare benefits for cows, increases productivity, and has lifestyle advantages for dairy farmers. This paper examines how established ethical relations on dairy farms are unsettled by the intervention of a radically different technology such as AMS. The renegotiation of ethical relationships is thus an important dimension of how the actors involved are re-assembled around a new technology. The paper draws on in-depth research on UK dairy farms comparing those using conventional milking technologies with those using AMS. We explore the situated ethical relations that are negotiated in practice, focusing on the contingent and complex nature of human-animal-technology interactions. We show that ethical relations are situated and emergent, and that as the identities, roles, and subjectivities of humans and animals are unsettled through the intervention of a new technology, the ethical relations also shift. © 2013 Springer Science+Business Media Dordrecht

Contextual factors among indiscriminate or larger attacks on food or water supplies, 1946-2015

This research updates previous inventories of malicious attacks on food and water to include data from 1946 through mid-2015. A systematic search of news reports, databases and previous inventories of poisoning events was undertaken. Incidents that threatened or were intended to achieve direct harm to humans, and that were either relatively large (number of victims > 4 or indiscriminate in intent or realisation were included. Agents could be chemical, biological or radio-nuclear. Reports of candidate incidents were subjected to systematic inclusion and exclusion criteria as well as validity analysis (not always clearly undertaken in previous inventories of such attacks). We summarise contextual aspects of the attacks that may be important for scenario prioritisation, modelling and defensive preparedness. Opportunity is key to most realised attacks, particularly access to dangerous agents. The most common motives and relative success rate in causing harm were very different between food and water attacks. The likelihood that people were made ill or died also varied by food/water mode, and according to motive and opportunity for delivery of the hazardous agent. Deaths and illness associated with attacks during food manufacture and prior to sale have been fewer than those in some other contexts. Valuable opportunities for food defence improvements are identified in other contexts, especially food prepared in private or community settings