Ramsey-type theorems for lines in 3-space

We prove geometric Ramsey-type statements on collections of lines in 3-space. These statements give guarantees on the size of a clique or an independent set in (hyper)graphs induced by incidence relations between lines, points, and reguli in 3-space. Among other things, we prove that: (1) The intersection graph of n lines in R^3 has a clique or independent set of size Omega(n^{1/3}). (2) Every set of n lines in R^3 has a subset of n^{1/2} lines that are all stabbed by one line, or a subset of Omega((n/log n)^{1/5}) such that no 6-subset is stabbed by one line. (3) Every set of n lines in general position in R^3 has a subset of Omega(n^{2/3}) lines that all lie on a regulus, or a subset of Omega(n^{1/3}) lines such that no 4-subset is contained in a regulus. The proofs of these statements all follow from geometric incidence bounds -- such as the Guth-Katz bound on point-line incidences in R^3 -- combined with Tur\'an-type results on independent sets in sparse graphs and hypergraphs. Although similar Ramsey-type statements can be proved using existing generic algebraic frameworks, the lower bounds we get are much larger than what can be obtained with these methods. The proofs directly yield polynomial-time algorithms for finding subsets of the claimed size.Comment: 18 pages including appendi

Ontogeny modifies the effects of water stress on stomatal control, leaf area duration and biomass partitioning of Pennisetum glaucum

International audience• Experiments are presented that test the relative importance, during ontogeny, of stomatal control and leaf area expansion to optimum seasonal water use in pearl millet (Pennisetum glaucum). These parameters play a key role in the compromise between plant growth and water saving under unpredictable conditions of semiarid environments. • The response of growth and water use of crops to successive 15 d drought periods was measured under field conditions in Niger (West Africa). • From emergence to anthesis, biomass partitioning to stems and panicles depended strongly on leaf area development. Water use was linearly related to green leaf area duration in well watered plots, but was reduced proportionally more than green leaf area in drought-affected plots. The relations of crop growth rate and transpiration efficiency to leaf area depended on ontogenetic changes in biomass partitioning. • In P. glaucum , stomata play a dominant role in reducing crop water use under preanthesis drought, although this control becomes negligible after anthesis because of ontogenetic decline in the range of stomatal conductance. The rate of leaf senescence after anthesis is not drought-dependent

A content analysis of vocabulary instruction in high school commercial literacy programs

The purpose of this study was to analyze the teachers’ manuals of the leading commercial high school reading programs to determine the extent to which they provide effective vocabulary instruction as advocated by the leading professional organizations in literacy. By synthesizing the standards of instruction from professional organizations, effective practices for teaching vocabulary and improving students’ overall performance were determined. This study evaluated the 3 leading commercial reading programs for high school students, READ 180, Fast Track, and Language!, and revealed that none of these programs met all the standards required for effective instruction

The Balian-Br\'ezin Method in Relativistic Quantum Mechanics

The method suggested by Balian and Br\'ezin for treating angular momentum reduction in the Faddeev equations is shown to be applicable to the relativistic three-body problem.Comment: 14 pages in LaTe

A learning organization in the service of knowledge management among nurses: A case study

AbstractIt becomes critical for health care organizations to develop strategies that aim to design new work practices and to manage knowledge. The introduction of learning organizations is seen as a promising choice for better knowledge management and continuing professional development in health care. This study analyzes the effects of a learning organization on nurses’ continuing professional development, knowledge management, and retention in a health and social services centre in Quebec, Canada. The learning organization seemed to affect daily nursing work in a positive manner, despite its variable impact on other professionals and other sites outside the hospital centre. These changes were particularly pronounced with respect to knowledge transfer, support for nursing practices, and quality of health care, objectives that the learning organization had sought to meet since its inception. However, it seemed to have a limited effect on nurse retention

'To wait or not to wait':lessons from running a wait-list controlled trial (ELSA) of a volunteer befriending service at the end of life within NHS, hospice and voluntary sectors

Background: Many innovations in palliative care are implemented without robust understanding of their effect. Trials are underused as they can be considered ethically and pragmatically challenging. Wait-list designs show promise as they enable all participants to receive the intervention, but with the rigour of a controlled trial. Aim: To provide recommendations on running wait-list trials in partnership with lay researchers within the hospice and voluntary sectors. Methods: A wait-list controlled trial testing volunteer delivered social action befriending services across 11 hospice, charity and NHS sites. Many non-clinical staff are responsible for site trial management and informed consent procedures, prepared with innovative face to face role play workshops. Participants are estimated to be in their last year of life, randomly allocated to receive the befriending intervention immediately or after a four week wait. Data collection at baseline, 4, 8 weeks: WHO QOL BREF, Loneliness scale, mMOS-SS, social networks. Intention to treat analysis includes fitting a linear mixed effect model to each outcome variable at 4, 8 and 12 weeks. ISRCTN 12929812 Results: Participants (currently n=117, recruitment commenced 6/15, completes 12/15) are currently at all trial stages. Methodological challenges centre on ‘the wait’. Initiation issues include acknowledging site staff design concerns and involving them in developing the protocol and documentation. Ongoing ‘wait’ issues involve providing support to address informed consent concerns and understanding trial procedures, addressing disappointment of ‘the wait’ allocation, allocating volunteers in a timely fashion, and the impact this has on understanding effect for this design. Conclusions: It is possible to run a rigorous and ethical wait-list trial in partnership with non-clinical site staff and volunteers. Key considerations include assessment of the wait period and data collection timing, understanding providing a service in the context of a trial, and clear responsive communications to support staff

Panel Discussion: Ideas for an Enjoyable and Productive Sabbatical

Navigating the Sabbatical Process and Deciding on a Productive Activity Can Be Challenging. a Sabbatical Can Take Many Different Forms Depending on Career Goals, Interests, and Institution. the Purpose of This Panel Discussion is to Provide Faculty Who Have Yet to Conduct a Sabbatical with Ideas of Activities and the Process. a Variety of Personal Experiences Will Be Presented of Sabbatical Activities that Were Enjoyable and Productive. These May Include Sabbaticals Focused on Independent Engineering Research, Engineering Education Research, Development of Classes or Programs, Industry or Government Collaboration, And/or Travel. Discussion Topics Will Also Include Process Requirements of Applying, Conducting, and Documenting the Outcomes of the Sabbatical. the Suggested Layout of the Panel Session Is: • 5-Minute Introduction of Panel Topic and Panelists • overview of Each Panelist\u27s Sabbatical Activity (5 Minutes Each) • Brief Whole Group Q&A Session to Engage Audience and Panelists • Small Group Activities with Documentation of Q&A: O What Resources Did You Find Helpful in Planning Your Sabbatical? O What Was the Timeframe of Planning, Applying For, Conducting, and Documenting Your Sabbatical? O What Were the Requirements of Your Sabbatical? O When or How Often Have You Conducted a Sabbatical? • Bring Whole Group Back Together to Discuss Learnings

Robustness of sex-differences in functional connectivity over time in middle-aged marmosets

Nonhuman primates (NHPs) are an essential research model for gaining a comprehensive understanding of the neural mechanisms of neurocognitive aging in our own species. In the present study, we used resting state functional connectivity (rsFC) to investigate the relationship between prefrontal cortical and striatal neural interactions, and cognitive flexibility, in unanaesthetized common marmosets (Callithrix jacchus) at two time points during late middle age (8 months apart, similar to a span of 5-6 years in humans). Based on our previous findings, we also determine the reproducibility of connectivity measures over the course of 8 months, particularly previously observed sex differences in rsFC. Male marmosets exhibited remarkably similar patterns of stronger functional connectivity relative to females and greater cognitive flexibility between the two imaging time points. Network analysis revealed that the consistent sex differences in connectivity and related cognitive associations were characterized by greater node strength and/or degree values in several prefrontal, premotor and temporal regions, as well as stronger intra PFC connectivity, in males compared to females. The current study supports the existence of robust sex differences in prefrontal and striatal resting state networks that may contribute to differences in cognitive function and offers insight on the neural systems that may be compromised in cognitive aging and age-related conditions such as mild cognitive impairment and Alzheimer\u27s disease

Measuring Changes in Brain Metabolite Levels Using Live-animal Magnetic Resonance Spectroscopy and Offline LC-MS Metabolomics in a Binge-ethanol Murine Model

Alcoholism and acute alcohol binge are significant public health concerns. Liquid chromatography-mass spectrometry (LC-MS) based metabolomics is a robust and sensitive technique for determining and quantifying transient or permanent biochemical changes within the central nervous system (CNS). However, access to human tissue and CNS biofluid for such analyses is limited in a clinical context. In-vivo magnetic resonance spectroscopy (MRS) is an attractive alternative for clinical measurement but currently the technique is limited to a small to a number of well-characterized, highly abundant analytes. We therefore seek to correlate LC-MS and MRS measurements to better understand and leverage the strengths of each. Following live animal MRS measurement, metabolites in hippocampal brain punch homogenates were quantified by LC-MS, and a Spearman’s correlation coefficient was calculated. We found that the measurements for glutamine and glutamate,, were significantly correlated. Other established neurochemicals, including NAA and aspartate, showed non-significant correlations. NAAG showed little correlation between the two measurements. Additional experiments are ongoing to resolve these discrepancies, and determine how to achieve better agreement between the two methods. In addition,, we used Elements (Proteome Software) to determine differentially expressed metabolites between ethanol exposed and control mice.. An initial pass shows more than 1000 peak-picked features identified in the two conditions, with approximately 200 analytes identified in the metabolite database (human) based on accurate mass. Differentially expressed candidates can be validated further using tandem mass spectrometry and, where possible, the use of authentic standards. Metabolites that change after binge ethanol exposure are reported along with an overview of comparing MRS with LC-MS datasets