1,996 research outputs found
Polyphase midâlatitude glaciation on Mars:Chronology of the formation of superposed glacierâlike forms from craterâcount dating
Reconstructing Mars's glacial history informs understanding of its physical environment and past climate. The known distribution of viscous flow features (VFFs) containing water ice suggests that its midâlatitudes were glaciated during the Late Amazonian period (the last several hundred million years). The identification of a subgroup of VFFsâcalled superposed glacier like forms (SGLFs)âflowing onto other VFFs, indicates multiple glacial phases may have occurred during this time. To explore the history and spatial extent of these glaciations, we record the distribution of SGLFs globally and use impactâcrater counting to date the SGLFs and the VFFs onto which they flow. Our inventory expands the handful of SGLFs reported in earlier literature to include 320 located throughout the midâlatitudes. Our dating reveals these SGLFs to be much younger than their underlying VFFs, which implies a spatiallyâasynchronous glaciation. SGLFs have been forming since âŒ65 Ma, and their ages are clustered in two distinct groups around 2â20 and 45â65 Ma, whereas the ages of their underlying VFFs span the last âŒ300 Ma diffusely. We discuss these results in the light of wellâknown uncertainties with the craterâdating method and infer that while ice sheets decayed over the Late Amazonian period, alpine glaciers waxed and waned in at least two major cycles before their final demise approximately two million years ago
THE FREQUENCIES OF HAPTOGLOBIN TYPES IN FIVE POPULATIONS *
Haptoglobin types have been determined by starch gel electrophoresis of blood from five populations. The gene frequencies obtained for allele Hp 1 were as follows: American whites, 043; American Negroes, 0.59; African Negroes, 0.72; Apaches, 0.59; and Asiatic Indians, 0.18. In tribes of the Ivory Coast and Liberia, there was a suggestion of a cline which parallels that for haemoglobin S. Evidence is presented that the condition of ahaptoglobinemia is under genetic control but not by a gene allelic to the Hp 1 -Hp 2 series. The importance of the ahaptoglobinemic individuals for genetic studies and the possibility of selection in the maintenance of the genetic polymorphism are discussed. The authors wish to acknowledge the excellent assistance of Alojzia Sandor, who carried out the electrophoretic separations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66263/1/j.1469-1809.1958.tb01460.x.pd
Stimulating the innovation potential of 'routine' workers through workplace learning
Governments worldwide seek to upgrade the âbasic skills' of employees deemed to have low literacy and numeracy, in order to enable their greater productivity and participation in workplace practices. A longitudinal investigation of such interventions in the United Kingdom has examined the effects on employees and on organizations of engaging in basic skills programmes offered in and through the workplace. âTrackingâ of employees in selected organizational contexts has highlighted ways in which interplay between formal and informal workplace learning can help to create the environments for employees in lower grade jobs to use and expand their skills. This workplace learning is a precondition, a stimulus and an essential ingredient for participation in employee-driven innovation, as workers engage with others to vary, and eventually to change, work practices. © 2010, SAGE Publications. All rights reserved
A standardised assessment scheme for conventional EEG in preterm infants
Objective: To develop a standardised scheme for assessing normal and abnormal electroencephalography (EEG) features of preterm infants. To assess the interobserver agreement of this assessment scheme. Methods: We created a standardised EEG assessment scheme for 6 different post-menstrual age (PMA) groups using 4 EEG categories. Two experts, not involved in the development of the scheme, evaluated this on 24 infants <32 weeks gestational age (GA) using random 2 hour EEG epochs. Where disagreements were found, the features were checked and modified. Finally, the two experts independently evaluated 2 hour EEG epochs from an additional 12 infants <37 weeks GA. The percentage of agreement was calculated as the ratio of agreements to the sum of agreements plus disagreements. Results: Good agreement in all patients and EEG feature category was obtained, with a median agreement between 80% and 100% over the 4 EEG assessment categories. No difference was found in agreement rates between the normal and abnormal features (p = 0.959). Conclusions: We developed a standard EEG assessment scheme for preterm infants that shows good interobserver agreement. Significance: This will provide information to Neonatal Intensive Care Unit (NICU) staff about brain activity and maturation. We hope this will prove useful for many centres seeking to use neuromonitoring during critical care for preterm infants
21 years of Timing PSR B1509-58
We present an updated timing solution for the young, energetic pulsar PSR
B1509-58 based on 21.3 years of radio timing data and 7.6 years of X-ray timing
data. No glitches have occurred in this time span, in contrast to other
well-studied young pulsars, which show frequent glitches. We report a
measurement of the third frequency derivative of (-1.28+/-0.21)x10^(-31)
s^(-4). This value is 1.65 standard deviations from, i.e. consistent with, that
predicted by the simple constant magnetic dipole model of pulsar spin-down. We
measured the braking index to be n=2.839+/-0.003 and show that it varies by
1.5% over 21.3 yr due to contamination from timing noise. Results of a
low-resolution power spectral analysis of the significant noise apparent in the
data yield a spectral index of alpha=-4.6+/-1.0 for the red noise component.Comment: 21 pages, 4 figures, 2 tables. Accepted by Ap
A failed RCT to determine if antibiotics prevent mastitis: Cracked nipples colonized with Staphylococcus aureus: A randomized treatment trial [ISRCTN65289389]
BACKGROUND: A small, non-blinded, RCT (randomised controlled trial) had reported that oral antibiotics reduced the incidence of mastitis in lactating women with Staphylococcus aureus (S. aureus)- colonized cracked nipples. We aimed to replicate the study with a more rigorous design and adequate sample size. METHODS: Our intention was to conduct a double-blind placebo-controlled trial to determine if an antibiotic (flucloxacillin) could prevent mastitis in lactating women with S. aureus-colonized cracked nipples. We planned to recruit two groups of 133 women with S. aureus-colonized cracked nipples. RESULTS: We spent over twelve months submitting applications to five hospital ethics committees and seven funding bodies, before commencing the trial. Recruitment to the trial was very slow and only ten women were randomized to the trial after twelve months, and therefore the trial was stopped early. CONCLUSIONS: In retrospect we should have conducted a feasibility study, which would have revealed the low number of women in these Melbourne hospitals (maternity wards and breastfeeding clinics) with damaged nipples. The appropriate use of antibiotics for breastfeeding women with cracked nipples still needs to be tested
Childrenâs rights online: challenges, dilemmas and emerging directions
In debates over internet governance, the interests of children figure unevenly, and only partial progress has been made in supporting childrenâs rights online globally. This chapter examines how the UN Convention on the Rights of the Child is helpful in mapping childrenâs rights to provision, protection and participation as they apply online as well as offline. However, challenges remain. First, opportunities and risks are positively linked, policy approaches are needed to resolve the potential conflict between protection on the one hand, and provision and participation on the other. Second, while parents may be relied on to some degree to balance their childâs rights and needs, the evidence suggests that a minority of parents are ill-equipped to manage this. Third, resolution is needed regarding the responsibility for implementing digital rights, since many governments prefer self-regulation in relation to internet governance. The chapter concludes by calling for a global governance body charged with ensuring the delivery of childrenâs rights
Predictive biometrics: A review and analysis of predicting personal characteristics from biometric data
Interest in the exploitation of soft biometrics information has continued to develop over the last decade or so. In comparison with traditional biometrics, which focuses principally on person identification, the idea of soft biometrics processing is to study the utilisation of more general information regarding a system user, which is not necessarily unique. There are increasing indications that this type of data will have great value in providing complementary information for user authentication. However, the authors have also seen a growing interest in broadening the predictive capabilities of biometric data, encompassing both easily definable characteristics such as subject age and, most recently, `higher level' characteristics such as emotional or mental states. This study will present a selective review of the predictive capabilities, in the widest sense, of biometric data processing, providing an analysis of the key issues still adequately to be addressed if this concept of predictive biometrics is to be fully exploited in the future
A Census Of Highly Symmetric Combinatorial Designs
As a consequence of the classification of the finite simple groups, it has
been possible in recent years to characterize Steiner t-designs, that is
t-(v,k,1) designs, mainly for t = 2, admitting groups of automorphisms with
sufficiently strong symmetry properties. However, despite the finite simple
group classification, for Steiner t-designs with t > 2 most of these
characterizations have remained longstanding challenging problems. Especially,
the determination of all flag-transitive Steiner t-designs with 2 < t < 7 is of
particular interest and has been open for about 40 years (cf. [11, p. 147] and
[12, p. 273], but presumably dating back to 1965). The present paper continues
the author's work [20, 21, 22] of classifying all flag-transitive Steiner
3-designs and 4-designs. We give a complete classification of all
flag-transitive Steiner 5-designs and prove furthermore that there are no
non-trivial flag-transitive Steiner 6-designs. Both results rely on the
classification of the finite 3-homogeneous permutation groups. Moreover, we
survey some of the most general results on highly symmetric Steiner t-designs.Comment: 26 pages; to appear in: "Journal of Algebraic Combinatorics
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