The work of Jaroslav Pelikan on Insects of the order Thysanoptera.

Diese Arbeit ist eine kleine Ehrung für Doc. Ing. Dr. Jaroslav Pelikán, DrSc, einen bekannten Wissenschaftler auf den Gebieten der Entomologie, Theriologie und Ökologie. Er beschrieb rund 80 neue Arten und sieben neue Gattungen von Fransenflüglern (Thysanoptera). Seine Arbeiten auf nationaler Ebene schliessen neben detaillierteren Beiträgen zur Fauna der Tschechoslowakei einige Checklisten ein. Am 22. April 2006 feierte Jaroslav Pelikán seinen 80. Geburtstag.The paper is a small tribute to Doc. Ing. Dr. Jaroslav Pelikán, DrSc, who has been a reputable scientist in the fields of entomology, theriology and ecology. He described about 80 new species of thrips as well as seven new genera of Thysanoptera. His national contributions included several checklists, together with his more complex contribution within the Fauna of Czechoslovakia. On the 22nd of April 2006 Jaroslav Pelikán celebrated his 80th birthday

Diel rhythmicity in amino acid uptake by Prochlorococcus

The marine cyanobacterium Prochlorococcus, the most abundant phototrophic organism on Earth, numerically dominates the phytoplankton in nitrogen (N)-depleted oceanic gyres. Alongside inorganic N sources such as nitrite and ammonium, natural populations of this genus also acquire organic N, specifically amino acids. Here, we investigated using isotopic tracer and flow cytometric cell sorting techniques whether amino acid uptake by Prochlorococcus is subject to a diel rhythmicity, and if so, whether this was linked to a specific cell cycle stage. We observed, in contrast to diurnally similar methionine uptake rates by Synechococcus cells, obvious diurnal rhythms in methionine uptake by Prochlorococcus cells in the tropical Atlantic. These rhythms were confirmed using reproducible cyclostat experiments with a light synchronised axenic Prochlorococcus (PCC9511 strain) culture and 35S-methionine and 3H-leucine tracers. Cells acquired the tracers at lower rates around dawn and higher rates around dusk despite >104 times higher concentration of ammonium in the medium, presumably because amino acids can be directly incorporated into protein. Leucine uptake rates by cells in the S+G2 cell cycle stage were consistently 2.2 times higher than those of cells at the G1 stage. Furthermore, S+G2 cells up-regulated amino acid uptake 3.5 times from dawn to dusk to boost protein synthesis prior to cell division. Because Prochlorococcus populations can account from 13% at midday, and up to 42% at dusk, of total microbial uptake of methionine and probably of other amino acids in N-depleted oceanic waters, this genus exerts diurnally variable, strong competitive pressure on other bacterioplankton populations

Twinning of cubic diamond explains reported nanodiamond polymorphs

The unusual physical properties and formation conditions attributed to h-, i-, m-, and n-nanodiamond polymorphs has resulted in their receiving much attention in the materials and planetary science literature. Their identification is based on diffraction features that are absent in ordinary cubic (c-) diamond (space group: Fd-3m). We show, using ultra-high-resolution transmission electron microscope (HRTEM) images of natural and synthetic nanodiamonds, that the diffraction features attributed to the reported polymorphs are consistent with c-diamond containing abundant defects. Combinations of {113} reflection and rotation twins produce HRTEM images and d-spacings that match those attributed to h-, i-, and m-diamond. The diagnostic features of n-diamond in TEM images can arise from thickness effects of c-diamonds. Our data and interpretations strongly suggest that the reported nanodiamond polymorphs are in fact twinned c-diamond. We also report a new type of twin ( rotational), which can give rise to grains with dodecagonal symmetry. Our results show that twins are widespread in diamond nanocrystals. A high density of twins could strongly influence their applications

Human Sprint Running Mechanics: Do Right and Left Legs Apply Equal Ground Forces?

Introduction: A growing body of research has focused on between-leg asymmetry as a critical factor for athletic performance and dysfunction. Specifically, various measures of between-leg asymmetry during running have been investigated in both healthy and injured populations. However, while the most important factor for running performance is the magnitude and rate of ground force application, it is not known whether the right and left legs typically apply equal ground forces at faster running speeds. Objective: In a healthy population of athletic female participants, we aimed to: 1) compare the mechanics of ground force application between right and left legs during moderate and top speed running, and 2) evaluate if the right vs. left leg asymmetries observed at intermediate speeds are more pronounced at faster speeds. Hypothesis: We hypothesized that the forces applied by the right and left legs of healthy athletes would agree to within 10% or less at both moderate and top speed. Participants: Nine female intercollegiate soccer players volunteered for the study (age: 19.4 ± 1.0 years, height: 1.72 ± 0.04 m, mass: 69.0 ± 7.2 kg). Data Collection: Ground force data was acquired at 1,000 Hz using a custom high-speed, three-axis force treadmill (AMTI, Watertown, MA). Data was analyzed for trials at 5.0 m•s-1 and each individual’s top speed. Top speed was defined as the fastest speed where the participant could complete eight consecutive steps on the treadmill without drifting backward more than 0.2 m. Outcome Measures: Ground contact time, vertical force, and vertical impulse were analyzed. Vertical force was normalized to body weight (Wb) and vertical impulse was calculated in body weight • seconds (Wb•s). For all trials, these variables were averaged for right vs. left footfalls, and percentage difference was calculated to quantify between-leg asymmetry. Results: Top speeds ranged from 7.21 to 8.26 m•s-1 (7.83 ± 0.38 m•s-1). At 5.0 m•s-1, the mean between-leg asymmetry was 2.3 ± 1.2 % for ground contact time, 1.9 ± 1.3 % for vertical force, and 2.3 ± 1.9 % for vertical impulse. At top speed, the mean between-leg asymmetry was 3.5 ± 2.8 % for ground contact time, 5.5 ± 3.0 % for vertical force, and 8.3 ± 4.8 % for vertical impulse. Conclusions: We conclude that the right and left legs apply ground force similarly during moderate and top-speed sprint running in healthy female athletes

A general relationship links gait mechanics and running ground reaction forces

The relationship between gait mechanics and running ground reaction forces is widely regarded as complex. This viewpoint has evolved primarily via efforts to explain the rising edge of vertical force– time waveforms observed during slow human running. Existing theoretical models do provide good rising-edge fits, but require more than a dozen input variables to sum the force contributions of four or more vague components of the body’s total mass (mb). Here, we hypothesized that the force contributions of two discrete body mass components are sufficient to account for vertical ground reaction force– time waveform patterns in full (stance foot and shank, m1=0.08mb; remaining mass, m2=0.92mb). We tested this hypothesis directly by acquiring simultaneous limb motion and ground reaction force data across a broad range of running speeds (3.0–11.1 m s−1 ) from 42 subjects who differed in body mass (range: 43–105 kg) and foot-strike mechanics. Predicted waveforms were generated from our two-mass model using body mass and three stride-specific measures: contact time, aerial time and lower limb vertical acceleration during impact. Measured waveforms (N=500) differed in shape and varied by more than twofold in amplitude and duration. Nonetheless, the overall agreement between the 500 measured waveforms and those generated independently by the model approached unity (R2 =0.95 ±0.04, mean±s.d.), with minimal variation across the slow, medium and fast running speeds tested (ΔR2 ≤0.04), and between rear-foot (R2 =0.94±0.04, N=177) versus fore-foot (R2 =0.95±0.04, N=323) strike mechanics. We conclude that the motion of two anatomically discrete components of the body’s mass is sufficient to explain the vertical ground reaction force–time waveform patterns observed during human running

Running impact forces: from half a leg to holistic understanding – comment on Nigg et al.

Running impact forces have immediate relevance for the muscle tuning paradigm proposed here and broader relevance for overuse injuries, shoe design and running performance. Here, we consider their mechanical basis. Several studies demonstrate that the vertical ground reaction force-time (vGRFT) impulse, from touchdown to toe-off, corresponds to the instantaneous accelerations of the body’s entire mass (Mb) divided into two or more portions. The simplest, a two-mass partitioning of the body (lower-limb, M1=0.08•Mb; remaining mass, M2=0.92•Mb) can account for the full vGRFT waveform under virtually all constant-speed, level-running conditions. Model validation data indicate that: 1) the non-contacting mass, M2, often accounts for one-third or more of the early “impact” portion of the vGRFT, and 2) extracting a valid impact impulse from measured force waveforms requires only lower-limb motion data and the fixed body mass fraction of 0.08 for M1

Efficient Bayesian model choice for partially observed processes: with application to an experimental transmission study of an infectious disease

Infectious diseases such as avian influenza pose a global threat to human health. Mathematical and statistical models can provide key insights into the mechanisms that underlie the spread and persistence of infectious diseases, though their utility is linked to the ability to adequately calibrate these models to observed data. Performing robust inference for these systems is challenging. The fact that the underlying models exhibit complex non-linear dynamics, coupled with practical constraints to observing key epidemiological events such as transmission, requires the use of inference techniques that are able to numerically integrate over multiple hidden states and/or infer missing information. Simulation-based inference techniques such as Approximate Bayesian Computation (ABC) have shown great promise in this area, since they rely on the development of suitable simulation models, which are often easier to code and generalise than routines that require evaluations of an intractable likelihood function. In this manuscript we make some contributions towards improving the efficiency of ABC-based particle Markov chain Monte Carlo methods, and show the utility of these approaches for performing both model inference and model comparison in a Bayesian framework. We illustrate these approaches on both simulated data, as well as real data from an experimental transmission study of highly pathogenic avian influenza in genetically modi fied chickens.This work was supported by the Biotechnology and Biological Sciences Research Council (grants BB/G00479X/1, BBS/B/00239, and BBS/B/00301) and by the Cambridge Infectious Diseases Consortium Department for Environment, Food and Rural Affairs-Higher Education Funding Council for England (grant VT0105). AJKC was supported by BBSRC grant BB/I024550/1

Symposium on basic writing, conflict and struggle, and the legacy of Mina Shaughnessy.

Two articles in the December 1992 College English presented historical perspectives on the field of Basic Writing. In Conflict and Struggle: The Enemies or Preconditions of Basic Writing? Min-Zhan Lu argued for the value of a pedagogy in which conflict and struggle help Basic Writers to reposition themselves; she suggested that resistance to such a pedagogy is traceable to three pioneers in the field, Kenneth Bruffee, Thomas Farrell, and Mina Shaughnessy, and the historical context in which they worked. In Waiting for an Aristotle, Paul Hunter analyzed the special issue of the Journal of Basic Writing published in 1980 as a memorial to Mina Shaughnessy, finding a conservative impulse both in its structure and in its reading of Shaughnessy\u27s message. This symposium presents several commentaries on Lu \u27s and Hunter\u27s articles, followed by the authors\u27 responses. Sources for all contributions to the Symposium are combined in a common Works Cited list at the end