Hydrodynamic Modes for Granular Gases

The eigenfunctions and eigenvalues of the linearized Boltzmann equation for inelastic hard spheres (d=3) or disks (d=2) corresponding to d+2 hydrodynamic modes, are calculated in the long wavelength limit for a granular gas. The transport coefficients are identified and found to agree with those from the Chapman-Enskog solution. The dominance of hydrodynamic modes at long times and long wavelengths is studied via an exactly solvable kinetic model. A collisional continuum is bounded away from the hydrodynamic spectrum, assuring a hydrodynamic description at long times. The bound is closely related to the power law decay of the velocity distribution in the reference homogeneous cooling state

Non-continuous and variable rate processes: Optimisation for energy use

The need to develop new and improved ways of reducing energy use and increasing energy intensity in industrial processes is currently a major issue in New Zealand. Little attention has been given to optimisation of non-continuous processes in the past, due to their complexity, yet they remain an essential and often energy intensive component of many industrial sites. Novel models based on pinch analysis that aid in minimising utility usage have been constructed here through the adaptation of proven continuous techniques. The knowledge has been integrated into a user friendly software package, and allows the optimisation of processes under variable operating rates and batch conditions. An example problem demonstrates the improvements in energy use that can be gained when using these techniques to analyse non-continuous data. A comparison with results achieved using a pseudo-continuous method show that the method described can provide simultaneous reductions in capital and operating costs

Minimising carbon emissions and energy expended for the New Zealand transport sector through to 2050

Carbon Emissions Pinch Analysis (CEPA) and Energy Return on Energy Investment (EROI) analysis are combined to investigate the feasibility of New Zealand (NZ) reaching a 1990 emission levels for transport in 2050. The transportation sector traditionally has been a difficult area to transition to high levels of renewable energy because of the strong dependency on fossil fuels. Multiple scenarios for reducing transport emissions are analysed. With NZ’s unique mix of renewable energy resources the analysis demonstrates that NZ is in a very good position to sustainably meet their future transport needs provided substantial commitment is made to transition light vehicle fleet to hybrid vehicles, plug-in hybrids vehicles and electric vehicles by 2050. Electrification of rail within and between major centres will also require major political commitment. The resulting increase in electricity demand for transport is 3.6 TWh (or 4.8 % of electricity generation in NZ). We show the minimum amount of biofuel renewable production to achieve the goal of 1990 emissions level in 2050 is 46 PJ. Delivering 46 PJ is expected to be well within the potential biofuel production capacity of NZ. The delivery of economically competitive renewable liquid biofuels will also require close cooperation and system integration with other energy systems like the electricity sector and industrial process heat sector

Submicrosecond pulsed atmospheric glow discharges sustained without dielectric barriers at kilohertz frequencies

In this letter, the authors report the experimental observation of a large-volume atmospheric glow discharge sustained without dielectric barriers at 1 kHz. This barrier-free mode of operation is made possible with a submicrosecond pulsed excitation instead of the usual sinusoidal excitation. Its current-voltage characteristics are shown to be very different from conventional atmospheric dielectric barrier discharges, and its generation mechanism is studied with nanosecond resolved optical emission spectroscopy. The pulsed barrier-free atmospheric plasma is shown to produce very intense atomic oxygen emission line at 777 nm, up to one magnitude more intensive than that of a comparable atmospheric dielectric barrier discharge

Contrasting characteristics of pulsed and sinusoidal cold atmospheric plasma jets

Pulsed excitation of cold atmospheric plasmas is commonly believed to offer valuable benefits compared to the mainstream sinusoidal excitation. However, direct comparison of pulsed and sinusoidal atmospheric plasmas remains few, if any, thus casting an uncertainty of whether pulsed excitation facilitates any significant advantage. In this letter, we report a comparison study of pulsed and sinusoidal cold atmospheric plasma jets through electrical characterization, gas temperature measurement, and optical detection of reactive plasma species. An example of pulsed excitation is shown to reduce the electrical energy consumption by a factor of 12 for producing the same amount of oxygen atoms

Cell surface proteins of the neutrophil in relation to chronic myeloid leukaemia

A large number of studies now suggest that non-random chromosomal changes are associated with human cancers. Certain chromosomes are involved more frequently in rearrangements, duplications and deletions than would be expected by chance. The most consistently observed chromosome abnormality is the Philadelphia chromosome, (Ph') which is found in a number of heamopoetic cell lineages in some 90% of patients sufferring from chronic myeloid leukaemia, (CML). Despite the diagnostic significance of the Ph' chromosome virtually nothing is known about its role in the origin and development of the disease. Well established phenotypic alterations in the mature neutrophil in CML are limited to the finding of a reduced level of alkaline phophatase in these cells. However, membrane-related phenomena, including phagocytosis and lectin agglutination have been shown to be altered. This study was undertaken to determine whether simple consistent alterations in cell membrane proteins were detectable at the molecular level which might underlie the membrane-related phenomena noted above and could be related to the chromosomal changes which occur in this leukaemia. Labelling of the membrane proteins of the cell chosen for study, the neutrophil, revealed at least thirteen relatively high molecular weight polypeptides bands which were identified using the 125I-lactoperoxidase labelling technique, on SDS-PAGE. To demonstrate that the labelled polypeptides were present on the cell surface, three independent methods were used: plasma membrane isolation, trypsin sensitivity and labelling in the presence and absence of exogenous enzymes. Extraction with the non-ionic detergent, Triton X-100 considerably reduced problems of handling and proteolytic digestion associated with this cell. Evidence is presented that non-ionic detergents, (TX-100 and NP-40), extract polypeptides selectively which may have structural significance. One major coomassie blue staining band, of mol. wt. 85K, a minor band of mol. wt. 25K and one broad radiolabelled band of mol. wt. 55-60K were particularly selectively retained in a residual pellet. Experiments using Concanavalin A (Con A) affinity chromatography showed that most of the labelled polypeptides were glycosylated. One major band was unique in that it showed no binding to Con A either by affinity chromatography or by the use of 125I-Con A overlay on SDS-PAGE. It is the major cell surface receptor for Wheat Germ Agglutinin (WGA) which binds to terminal sialic acid residues. when labelled cells were treated with neuraminidase there was an apparent decrease in the mobility of this polypeptide and binding to WGA was abolished. No other labelled band showed significant alteration following neuraminidase treatment. The above evidence suggests that this glycoprotein of mol. wt. 115K approx., (Gp 115K), is the major sialoglycoprotein at the cell surface of the human neutrophil. This finding may be of general interest since it shares a number of the features, described above, with other 'glycophorin-like' sialoglycoproteins reported in the literature. The function of this unusual class of cell surface glycoproteins is not clear, but they appear to make a significant contribution to the net negative charge at the cell surface and to lack secondary or tertiary structure in the extracellular portion. Membrane related phenomena of the human neutrophil appear to undergo alterations in CML. Cell surface polypeptides were labelled directly using the 125I-LPO method and radio-labelled lectins (Con A and WGA) were overlayed on whole cell detergent extracts run on SDS-PAGE, in order to try and detect alterations in glycosylation. The results suggest that large scale alterations in the expression of glycosylated, and in particular cel1-surface, proteins do not occur. No evidence for novel gene products or marked alteration in glycosylation of neutrophils in CML was found

Generalized Quantum Theory of Recollapsing Homogeneous Cosmologies

A sum-over-histories generalized quantum theory is developed for homogeneous minisuperspace type A Bianchi cosmological models, focussing on the particular example of the classically recollapsing Bianchi IX universe. The decoherence functional for such universes is exhibited. We show how the probabilities of decoherent sets of alternative, coarse-grained histories of these model universes can be calculated. We consider in particular the probabilities for classical evolution defined by a suitable coarse-graining. For a restricted class of initial conditions and coarse grainings we exhibit the approximate decoherence of alternative histories in which the universe behaves classically and those in which it does not. For these situations we show that the probability is near unity for the universe to recontract classically if it expands classically. We also determine the relative probabilities of quasi-classical trajectories for initial states of WKB form, recovering for such states a precise form of the familiar heuristic "J d\Sigma" rule of quantum cosmology, as well as a generalization of this rule to generic initial states.Comment: 41 pages, 4 eps figures, revtex 4. Modest revisions throughout. Physics unchanged. To appear in Phys. Rev.

No Evidence for a Cumulative Impact Effect on Concussion Injury Threshold

Recent studies using a helmet-based accelerometer system (Head Impact Telemetry System [HITS]) have demonstrated that concussions result from a wide range of head impact magnitudes. Variability in concussion thresholds has been proposed to result from the cumulative effect of non-concussive head impacts prior to injury. We used the HITS to collect biomechanical data representing >100,000 head impacts in 95 high school football players over 4 years. The cumulative impact histories prior to 20 concussive impacts in 19 athletes were compared to the cumulative impact histories prior to the three largest magnitude non-concussive head impacts in the same athletes. No differences were present in any impact history variable between the concussive and non-concussive high magnitude impacts. These analyses included the number of head impacts, cumulative HIT severity profile value, cumulative linear acceleration, and cumulative rotational acceleration during the same practice or game session, as well as over the 30-min and 1 week preceding these impacts. Our data do not support the proposal that impact volume or intensity influence concussion threshold in high school football athletes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90490/1/neu-2E2011-2E1910.pd

Elite male Flat jockeys display lower bone density and lower resting metabolic rate than their female counterparts: implications for athlete welfare

To test the hypothesis that daily weight-making is more problematic to health in male compared with female jockeys, we compared the bone-density and resting metabolic rate (RMR) in weight-matched male and female Flat-jockeys. RMR (kcal.kg-1 lean mass) was lower in males compared with females as well as lower bone-density Z-scores at the hip and lumbar spine. Data suggest the lifestyle of male jockeys’ compromise health more severely than females, possibly due to making-weight more frequently