Starved picowatt oscillator for remote sensor wake-up timer

A sub-nanowatt oscillator is described. The oscillator is intended for a wake-up timer for remote sensors and hence trades frequency accuracy for reduced power consumption. It is constructed from a five-stage ring of inverters in which the switching speed is reduced using transistors that are always-off, or starved. Fabricated in a 0.35 μm process, the oscillator and its active load dissipate 80 pW at 1.5 Hz from a 1 V supply at 22°C.J.A. Kitchener and B.J. Phillip

Reinterpreting turbidity: new methodologies for suspended-sediment research

Existing instruments for turbidity measurement vary considerably in terms of the principles of operation, the physical design, and the cost to the researcher. The operational methodologies of late twentieth century turbidity instruments have led to the development of new turbidity measurement standards, and the invention of new turbidity measurement units. These measurement units are invalid and do not have a sound footing with regard to the underlying physics of the scattering and absorption of light by suspended particles. A review of the turbidity literature has shown that the proliferation of these incommensurate units of measurement throughout the physical sciences has caused extensive misinterpretation of turbidity data, particularly concerning its use as a surrogate for suspended sediment concentration (SSC). Turbidity is a complex phenomenon, and its measurement reported in terms of a single numeric quantity in some physically indeterminate units of measurement. It is not necessarily useful to reduce complex data to a single value, since this approach does not permit the researcher any a posteriori opportunity to reinterpret existing data in light of innovations in analysis methodology. This thesis proposes a new way to present turbidity data that will facilitate the cross-comparison of turbidity measurements made by different instruments on any type of suspended sediment. The creation of a new turbidity research instrument that illustrates the application of the new method for reporting turbidity data as a ratio of light attenuation values in decibels, promotes a positive change in direction away from the traditional measurement units. The design process focusses on the instrument calibration procedure. With a simple reinterpretation of the phase-function description of light scattering from suspended particles, measurements of light attenuation made at multiple angles with respect to the axis of the incident light beam, compare easily with the same measurements made using different wavelengths of incident light. This work goes on to introduce new nomenclature that requires the citing of measurement angle and wavelength of light to be an integral part of any recorded turbidity measurement. A modelling approach is used in the evaluation of the new turbidity instrument. This modelling is important for three reasons. First, it identifies which instrument parameters affect the result of a turbidity measurement – the key parameter being the mathematical function that describes the spatial divergence of the incident light beam, which is important to measurement systems that employ incoherent light sources such as LEDs, rather than to laser-based systems. Secondly, the modelling reveals two fundamental theories of light scattering due to suspended particles, both of which are required to describe adequately the turbidity of sediment-laden water. These two theories are Mie scattering and geometric optics. Mie scattering is well accounted for by the developed model - geometric optics, less so. The extent to which the model predictions diverge from the empirical data is characterised by a metric related to the backscatter fraction, and the consistency and linearity of the model is established. Ideas for the improvement of the geometric optics feature of the model are discussed, as is the third reason for the importance of numerical modelling. This third reason relates to the use of multi-parameter turbidity measurements as a means to characterise the properties of a suspended sediment. By simulating precisely the measurement response of the turbidity instrument, then it is notionally possible to infer the properties of an unknown sediment by tuning the model parameters to match the empirical response of the unknown sediment. This tuning process could reveal information pertaining to particle size and shape. Finally, potential applications for the new research instrument focus on improvements to the instrument itself and the methodology, and the further development of the turbidity data reporting nomenclature. Prototype methodologies that relate turbidity to suspended sediment concentration are suggested, which also consider ways in which the optical measurements can potentially classify the physical properties of a sediment

Oldest known pantherine skull and evolution of the tiger

The tiger is one of the most iconic extant animals, and its origin and evolution have been intensely debated. Fossils attributable to extant pantherine species-lineages are less than 2 MYA and the earliest tiger fossils are from the Calabrian, Lower Pleistocene. Molecular studies predict a much younger age for the divergence of modern tiger subspecies at <100 KYA, although their cranial morphology is readily distinguishable, indicating that early Pleistocene tigers would likely have differed markedly anatomically from extant tigers. Such inferences are hampered by the fact that well-known fossil tiger material is middle to late Pleistocene in age. Here we describe a new species of pantherine cat from Longdan, Gansu Province, China, Panthera zdanskyi sp. nov. With an estimated age of 2.55–2.16 MYA it represents the oldest complete skull of a pantherine cat hitherto found. Although smaller, it appears morphologically to be surprisingly similar to modern tigers considering its age. Morphological, morphometric, and cladistic analyses are congruent in confirming its very close affinity to the tiger, and it may be regarded as the most primitive species of the tiger lineage, demonstrating the first unequivocal presence of a modern pantherine species-lineage in the basal stage of the Pleistocene (Gelasian; traditionally considered to be Late Pliocene). This find supports a north-central Chinese origin of the tiger lineage, and demonstrates that various parts of the cranium, mandible, and dentition evolved at different rates. An increase in size and a reduction in the relative size of parts of the dentition appear to have been prominent features of tiger evolution, whereas the distinctive cranial morphology of modern tigers was established very early in their evolutionary history. The evolutionary trend of increasing size in the tiger lineage is likely coupled to the evolution of its primary prey species

Mental health first aid training for high school teachers: a cluster randomized trial

Extent: 12p.BACKGROUND: Mental disorders often have their first onset during adolescence. For this reason, high school teachers are in a good position to provide initial assistance to students who are developing mental health problems. To improve the skills of teachers in this area, a Mental Health First Aid training course was modified to be suitable for high school teachers and evaluated in a cluster randomized trial. METHODS: The trial was carried out with teachers in South Australian high schools. Teachers at 7 schools received training and those at another 7 were wait-listed for future training. The effects of the training on teachers we reevaluated using questionnaires pre- and post-training and at 6 months follow-up. The questionnaires assessed mental health knowledge, stigmatizing attitudes, confidence in providing help to others, help actually provided, school policy and procedures, and teacher mental health. The indirect effects on students were evaluated using questionnaires at pre-training and at follow-up which assessed any mental health help and information received from school staff, and also the mental health of the student. RESULTS: The training increased teachers’ knowledge, changed beliefs about treatment to be more like those of mental health professionals, reduced some aspects of stigma, and increased confidence in providing help to students and colleagues. There was an indirect effect on students, who reported receiving more mental health information from school staff. Most of the changes found were sustained 6 months after training. However, no effects were found on teachers’ individual support towards students with mental health problems or on student mental health. CONCLUSIONS: Mental Health First Aid training has positive effects on teachers’ mental health knowledge, attitudes, confidence and some aspects of their behaviour.Anthony F. Jorm, Betty A Kitchener, Michael G. Sawyer, Helen Scales and Stefan Cvetkovsk

ARTISTIC: A randomised trial of human papillomavirus (HPV) testing in primary cervical screening

The official published version of the article can be found at the link below.Objectives: Primary cervical screening uses cytology to detect cancer precursor lesions [cervical intraepithelial neoplasia stage 3 or beyond (CIN3+)]. Human papillomavirus (HPV) testing could add sensitivity as an adjunct to cytology or as a first test, reserving cytology for HPV-positive women. This study addresses the questions: Does the combination of cytology and HPV testing achieve a reduction in incident CIN3+?; Is HPV testing cost-effective in primary cervical screening?; Is its use associated with adverse psychosocial or psychosexual effects?; and How would it perform as an initial screening test followed by cytology for HPV positivity? Design: ARTISTIC was a randomised trial of cervical cytology versus cervical cytology plus HPV testing, evaluated over two screening rounds, 3 years apart. Round 1 would detect prevalent disease and round 2 a combination of incident and undetected disease from round 1. Setting: Women undergoing routine cervical screening in the NHS programme in Greater Manchester. Participants: In total 24,510 women aged 20–64 years were enrolled between July 2001 and September 2003. Interventions: HPV testing was performed on the liquid-based cytology (LBC) sample obtained at screening. Women were randomised in a ratio of 3:1 to have the HPV test result revealed and acted upon if persistently positive in cytology-negative cases or concealed. A detailed health economic evaluation and a psychosocial and psychosexual assessment were also performed. Main outcome measures: The primary outcome was CIN3+ in round 2. Secondary outcomes included an economic assessment and psychosocial effects. A large HPV genotyping study was also conducted. Results: In round 1 there were 313 CIN3+ lesions, representing a prevalence in the revealed and concealed arms of 1.27% and 1.31% respectively (p = 0.81). Round 2 (30–48 months) involved 14,230 (58.1%) of the women screened in round 1 and only 31 CIN3+ were detected; the CIN3 rate was not significantly different between the revealed and concealed arms. A less restrictive definition of round 2 (26–54 months) increased CIN3+ to 45 and CIN3+ incidence in the arms was significantly different (p = 0.05). There was no difference in CIN3+ between the arms when rounds 1 and 2 were combined. Prevalence of highrisk HPV types was age-dependent. Overall prevalence of HPV16/18 increased with severity of yskaryosis. Mean costs per woman in round 1 were £72 and £56 for the revealed and concealed arms (p < 0.001); an age-adjustment reduced these mean costs to £65 and £52. Incremental cost-effectiveness ratio for detecting additional CIN3+ by adding HPV testing to LBC screening in round 1 was £38,771. Age-adjusted mean cost for LBC primary screening with HPV triage was £39 compared with £48 for HPV primary screening with LBC triage. HPV testing did not appear to cause significant psychosocial distress. Conclusions: Routine HPV testing did not add significantly to the effectiveness of LBC in this study. No significant adverse psychosocial effects were detected. It would not be cost-effective to screen with cytology and HPV combined but HPV testing, as either triage or initial test triaged by cytology, would be cheaper than cytology without HPV testing. LBC would not benefit from combination with HPV; it is highly effective as primary screening but HPV testing has twin advantages of high negative predictive value and automated platforms enabling high throughput. HPV primary screening would require major contraction and reconfiguration of laboratory services. Follow-up continues in ARTISTIC while maintaining concealment for a further 3-year round of screening, which will help in screening protocol development for the post-vaccination era

nAChRs Mediate Human Embryonic Stem Cell-Derived Endothelial Cells: Proliferation, Apoptosis, and Angiogenesis

Many patients with ischemic heart disease have cardiovascular risk factors such as cigarette smoking. We tested the effect of nicotine (a key component of cigarette smoking) on the therapeutic effects of human embryonic stem cell-derived endothelial cells (hESC-ECs).To induce endothelial cell differentiation, undifferentiated hESCs (H9 line) underwent 4-day floating EB formation and 8-day outgrowth differentiation in EGM-2 media. After 12 days, CD31(+) cells (13.7+/-2.5%) were sorted by FACScan and maintained in EGM-2 media for further differentiation. After isolation, these hESC-ECs expressed endothelial specific markers such as vWF (96.3+/-1.4%), CD31 (97.2+/-2.5%), and VE-cadherin (93.7+/-2.8%), form vascular-like channels, and incorporated DiI-labeled acetylated low-density lipoprotein (DiI-Ac-LDL). Afterward, 5x10(6) hESC-ECs treated for 24 hours with nicotine (10(-8) M) or PBS (as control) were injected into the hearts of mice undergoing LAD ligation followed by administration for two weeks of vehicle or nicotine (100 microg/ml) in the drinking water. Surprisingly, bioluminescence imaging (BLI) showed significant improvement in the survival of transplanted hESC-ECs in the nicotine treated group at 6 weeks. Postmortem analysis confirmed increased presence of small capillaries in the infarcted zones. Finally, in vitro mechanistic analysis suggests activation of the MAPK and Akt pathways following activation of nicotinic acetylcholine receptors (nAChRs).This study shows for the first time that short-term systemic administrations of low dose nicotine can improve the survival of transplanted hESC-ECs, and enhance their angiogenic effects in vivo. Furthermore, activation of nAChRs has anti-apoptotic, angiogenic, and proliferative effects through MAPK and Akt signaling pathways

Rapid evolution of the primate larynx?

Tissue vibrations in the larynx produce most sounds that comprise vocal communication in mammals. Larynx morphology is thus predicted to be a key target for selection, particularly in species with highly developed vocal communication systems. Here, we present a novel database of digitally modeled scanned larynges from 55 different mammalian species, representing a wide range of body sizes in the primate and carnivoran orders. Using phylogenetic comparative methods, we demonstrate that the primate larynx has evolved more rapidly than the carnivoran larynx, resulting in a pattern of larger size and increased deviation from expected allometry with body size. These results imply fundamental differences between primates and carnivorans in the balance of selective forces that constrain larynx size and highlight an evolutionary flexibility in primates that may help explain why we have developed complex and diverse uses of the vocal organ for communication