On-chip high-speed sorting of micron-sized particles for high-throughput analysis

A new design of particle sorting chip is presented. The device employs a dielectrophoretic gate that deflects particles into one of two microfluidic channels at high speed. The device operates by focussing particles into the central streamline of the main flow channel using dielectrophoretic focussing. At the sorting junction (T- or Y-junction) two sets of electrodes produce a small dielectrophoretic force that pushes the particle into one or other of the outlet channels, where they are carried under the pressure-driven fluid flow to the outlet. For a 40mm wide and high channel, it is shown that 6micron diameter particles can be deflected at a rate of 300particles/s. The principle of a fully automated sorting device is demonstrated by separating fluorescent from non-fluorescent latex beads

The position of women in the senior management of secondary schools

It is becoming increasingly recognised that women are not represented in the senior management area of secondary schools in the proportion that their numbers warrant. Government, local authorities and professional associations have drawn attention to the fact and have put forward suggestions, and in some areas have set schemes in motion, to increase female participation in the education service at this level. It is the purpose of this study to try to discover the reasons for women's under-representation in the higher echelons of secondary school management. Many secondary sources have been used to provide the historical and sociological background, in an effort to assess the effect of sex stereotyping, co-education and early socialisation on the aspirations of women in their careers. The empirical research has been provided by the views, obtained by questionnaire and interview, of 120 teachers of Scale 3 status and above from four urban comprehensive schools. In examining their views on factors affecting promotion and on leadership ideology it has been possible to link theory with practice and to assess the difference between men and women in their attitudes, in their qualificatio

Determining an average distance from the external mandibular cortex to the inferior alveolar canal using cone beam computed tomography (CBCT) imaging: An aid to harvesting mandibular ramus autogenous grafts.

OBJECTIVES: To provide average measurements relating the external mandibular cortex (EMC) to the inferior alveolar canal (IAC) using CBCT. METHODS: 100 CBCT images from UWC Dental hospital patient database were analysed using CBCT software (NewtomVGi Image works Corps) to produce coronal slices at four defined points along the IAC. Each point was measured from the IAC to the outer aspect of the mandibular buccal cortex and to the alveolar ridge crest (edentulous mandibles) or buccal cortical plate crest (dentate mandibles). The paired t-test was used to analyse right and left side measurements in order to test for differences in right and left side means. RESULTS: A mean width of 5.891mm (±1.09) from the IAC to the EMC in the horizontal plane and a mean height of 13.068mm (±2.963) from IAC to the alveolar crest or buccal cortical plate was demonstrated. Mean height was lower in edentulous mandibles (11.142mm in females; 13.490mm in males) than in dentate mandibles (12.916mm in females; 14.102 in males). There was no significant difference in width values. Height values were greater in males (14.102mm) than in females (12.916mm), being marginally significant (p-value of 0.00948:p<0.05). CONCLUSIONS: These measurements are clinically applicable when harvesting mandibular autogenous block grafts.DHE

Improving estimations of life history parameters of small animals in mesocosm experiments: a case study on mosquitoes

Mesocosm experiments enable researchers to study animal dynamics, but determining accurate estimates of survival and development rates of different life stages can be difficult, especially as the subjects may be hard to sample and mortality rates can be high. We propose a new methodology for estimating such parameters.We used an experimental set-up with 48 aquatic mesocosms, each with 20 first instar mosquito larvae and under 1 of 12 treatments with varying temperatures and nutrient concentrations. We took daily subsamples of the aquatic life stages as well as counting the emerging adults. We developed a method to estimate the survival and development probabilities at each life stage, based on optimising a matrix population model. We used two different approaches, one assuming the difference between predictions and observations was normally distributed, and the other using a combination of a normal and a multinomial distribution. For each approach, the resulting optimisation problem had around 100 parameters, making conventional gradient descent ineffective with our limited number of data points. We solved this by computing the formal derivatives of our matrix model.Both approaches proved effective in predicting mosquito populations over time, also when compared against a separate validation dataset, and the two approaches produced similar results. They also both predicted similar trends in the survival and development probabilities for each life stage, although there were some differences in the actual values. The approach which only used the normal distribution was considerably more computationally efficient than the mixed distribution approach.This is an effective approach for determining the survival and development rates of small animals in mesocosm experiments. We have not found any other reliable methodology for estimating these parameters, especially not from incomplete data or when there are many different experimental treatments. This methodology enables researchers to gain a much more detailed understanding of the life cycles of small animals, potentially leading to advances in a wide range of areas, for example in mosquito-borne disease risk or in considering the effects of biodiversity loss or climate change on different species.NWONWA.1160.1S.210Number theory, Algebra and Geometr

Prospectus, November 6, 2002

https://spark.parkland.edu/prospectus_2002/1029/thumbnail.jp

Prevalence and characterization of human mecC methicillin-resistant Staphylococcus aureus isolates in England

Objectives: There are limited data available on the epidemiology and prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in the human population that encode the recently described mecA homologue, mecC. To address this knowledge gap we undertook a prospective prevalence study in England to determine the prevalence of mecC among MRSA isolates.&lt;p&gt;&lt;/p&gt; Patients and methods: Three hundred and thirty-five sequential MRSA isolates from individual patients were collected from each of six clinical microbiology laboratories in England during 2011–12. These were tested by PCR or genome sequencing to differentiate those encoding mecA and mecC. mecC-positive isolates were further characterized by multilocus sequence typing, spa typing, antimicrobial susceptibility profile and detection of PBP2a using commercially available kits.&lt;p&gt;&lt;/p&gt; Results: Nine out of the 2010 MRSA isolates tested were mecC positive, indicating a prevalence among MRSA in England of 0.45% (95% CI 0.24%–0.85%). The remainder were mecA positive. Eight out of these nine mecC MRSA isolates belonged to clonal complex 130, the other being sequence type 425. Resistance to non-β-lactam antibiotics was rare among these mecC MRSA isolates and all were phenotypically identified as MRSA using oxacillin and cefoxitin according to BSAC disc diffusion methodology. However, all nine mecC isolates gave a negative result using three different commercial PBP2a detection assays. Conclusions: mecC MRSA are currently rare among MRSA isolated from humans in England and this study provides an important baseline prevalence rate to monitor future changes, which may be important given the increasing prevalence of mecC MRSA reported in Denmark.&lt;p&gt;&lt;/p&gt

Palaeontology, the biogeohistory of Victoria

The broad-scale distribution of fossils within Victoria is controlled by general global patterns in the biological evolution of life on Earth, the local development and environmental evolution of habitats, and the occurrence of geological processes conducive to the preservation of fossil floras and faunas. Early Palaeozoic fossils are mostly marine in origin because of the predominance of marine sedimentary rocks in Victoria and because life on land was not significant during most of this time interval. Middle Palaeozoic sequences have both terrestrial and marine fossil records. Within Victoria, marine rocks are only very minor components of strata deposited during the late Palaeozoic, so that few marine fossils are known from this time period. A similar situation existed during most of the Mesozoic except towards the end of this era when marine conditions began to prevail in the Bass Strait region. During long intervals in the Cainozoic, large areas of Victoria were flooded by shallow-marine seas, particularly in the southern basins of Bass Strait, as well as in the northwest of the State (Murray Basin). Cainozoic sediments contain an extraordinary range of animal and plant fossils. During the Quaternary, the landscape of Victoria became, and continues to be, dominated by continental environments including, at times, extensive freshwater lake systems. Fossil floras and faunas from sediments deposited in these lake systems and from other continental sediments, as well as from Quaternary sediments deposited in marginal marine environments, collectively record a history of rapid fluctuations in climate and sea level.<br /

Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory

Data from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius $A$. Also the events detected simultaneously by the surface and fluorescence detectors (the `hybrid' data set), which have better pointing accuracy but are less numerous than those of the surface array alone, do not show any significant localized excess from this direction.Comment: Matches published versio