41,070 research outputs found
Miniature capacitive accelerometer is especially applicable to telemetry
Capacitive accelerometer design enables the construction of highly miniaturized instruments having full-scale ranges from 1 g to several hundred g. This accelerometer is applicable to telemetry and can be tailored to cover any of a large number of acceleration ranges and frequency responses
Ultrastructural alteration of mouse lung by prolonged exposure to mixtures of helium and oxygen
Observed changes consist mainly of blebbing of capillary endothelium and alveolar epithelium, which is quite possibly indicative of cellular edema; also, there can be observed highly-convoluted basement membrane, alveolar debris, and increased numbers of platelets
UK Soils: their phosphorus sorption capacity and potential for P removal from sewage effluents in emergent hydrophyte treatment systems
Recommended from our members
Determining how atmospheric carbon dioxide concentrations have changed during the history of the Earth
The reconstruction of ancient atmospheric carbon dioxide concentrations is essential to understanding the history of the Earth and life. It is also an important guide to identifying the sensitivity of the Earth system to this greenhouse gas and, therefore, constraining its future impact on climate. However, determining the concentration of CO2 in ancient atmospheres is a challenging endeavour requiring the application of state-of-the-art analytical chemistry to geological materials, underpinned by an understanding of photosynthesis and biochemistry. It is truly an interdisciplinary challenge
SHAWEL: Sharable and interactive web-lexicons
A prototypical lexicon tool was implemented which was intended to allow researchers to collaboratively create lexicons of endangered languages. Increasingly often researchers documenting or analyzing a language work at different locations. Lexicons that evolve through continuous interaction between the collaborators can only be efficiently produced when it can be accessed and manipulated via the Internet. The SHAWEL tool was developed to address these needs; it makes use of a thin Java client and a central database solution
Teachers developing assessment for learning: impact on student achievement
While it is generally acknowledged that increased use of formative assessment (or assessment for learning) leads to higher quality learning, it is often claimed that the pressure in schools to improve the results achieved by students in externally-set tests and examinations precludes its use. This paper reports on the achievement of secondary school students who worked in classrooms where teachers made time to develop formative assessment strategies. A total of 24 teachers (2 science and 2 mathematics teachers, in each of six schools in two LEAs) were supported over a six-month period in exploring and planning their approach to formative assessment, and then, beginning in September 1999, the teachers put these plans into action with selected classes. In order to compute effect sizes, a measure of prior attainment and at least one comparison group was established for each class (typically either an equivalent class taught in the previous year by the same teacher, or a parallel class taught by another teacher). The mean effect size was 0.32
Comparative analysis of reliability models of a cable plant portraying summer and winter operating strategy
Finite pseudo orbit expansions for spectral quantities of quantum graphs
We investigate spectral quantities of quantum graphs by expanding them as
sums over pseudo orbits, sets of periodic orbits. Only a finite collection of
pseudo orbits which are irreducible and where the total number of bonds is less
than or equal to the number of bonds of the graph appear, analogous to a cut
off at half the Heisenberg time. The calculation simplifies previous approaches
to pseudo orbit expansions on graphs. We formulate coefficients of the
characteristic polynomial and derive a secular equation in terms of the
irreducible pseudo orbits. From the secular equation, whose roots provide the
graph spectrum, the zeta function is derived using the argument principle. The
spectral zeta function enables quantities, such as the spectral determinant and
vacuum energy, to be obtained directly as finite expansions over the set of
short irreducible pseudo orbits.Comment: 23 pages, 4 figures, typos corrected, references added, vacuum energy
calculation expande
A new quantum fluid at high magnetic fields in the marginal charge-density-wave system -(BEDT-TTF)Hg(SCN) (where ~K and Rb)
Single crystals of the organic charge-transfer salts
-(BEDT-TTF)Hg(SCN) have been studied using Hall-potential
measurements (K) and magnetization experiments ( = K, Rb). The data show
that two types of screening currents occur within the high-field,
low-temperature CDW phases of these salts in response to time-dependent
magnetic fields. The first, which gives rise to the induced Hall potential, is
a free current (), present at the surface of the sample.
The time constant for the decay of these currents is much longer than that
expected from the sample resistivity. The second component of the current
appears to be magnetic (), in that it is a microscopic,
quasi-orbital effect; it is evenly distributed within the bulk of the sample
upon saturation. To explain these data, we propose a simple model invoking a
new type of quantum fluid comprising a CDW coexisting with a two-dimensional
Fermi-surface pocket which describes the two types of current. The model and
data are able to account for the body of previous experimental data which had
generated apparently contradictory interpretations in terms of the quantum Hall
effect or superconductivity.Comment: 13 pages, 11 figure
Recommended from our members
An Investigation into the Effect of the Shell on SALM Processed Parts
Shell Assisted Layer Manufacturing (SALM) is a novel process for rapid prototyping/
tooling/ manufacture (RP/RT/RM) which is presently undergoing feasibility studies. SALM is
based on layered manufacturing technology (LMT). Initially it develops the shell (boundaries)
of a selected layer using a technique similar to fused deposition modelling (FDM). The
developed shell is filled with a UV curable resin and is exposed to UV radiation for curing.
This procedure is repeated until the complete part is built. This paper compares and contrasts
properties of parts made using two options available with the SALM technique: building the
part using a soluble shell (FDM support structure material, finally dissolved to recover the
part); or using a polymer material such as ABS that is bonded with the resin whilst making
the part.Mechanical Engineerin
- …