An investigation of surface albedo variations during the recent sahel drought

Applications Technology Satellite 3 green sensor data were used to measure surface reflectance variations in the Sahara/Sahel during the recent drought period; 1967 to 1974. The magnitude of the seasonal reflectance change is shown to be as much as 80% for years of normal precipitation and less than 50% for drought years. Year to year comparisons during both wet and dry seasons reveal the existence of a surface reflectance cycle coincident with the drought intensity. The relationship between the green reflectance and solar albedo is examined and estimated to be about 0.6 times the reflectance change observed by the green channel

Communications and tracking relay experiment study program Final report

Communications and tracking relay experimen

The Blackstone Series: Evidence for an Avalonian Plate Margin in Northern Rhode Island

Guidebook to geologic field studies in Rhode Island and adjacent areas: The 73rd annual meeting of the New England Intercollegiate Geological Conference, October 16-18, 1981: Trip B-

A Combination Theorem for Metric Bundles

We define metric bundles/metric graph bundles which provide a purely topological/coarse-geometric generalization of the notion of trees of metric spaces a la Bestvina-Feighn in the special case that the inclusions of the edge spaces into the vertex spaces are uniform coarsely surjective quasi-isometries. We prove the existence of quasi-isometric sections in this generality. Then we prove a combination theorem for metric (graph) bundles (including exact sequences of groups) that establishes sufficient conditions, particularly flaring, under which the metric bundles are hyperbolic. We use this to give examples of surface bundles over hyperbolic disks, whose universal cover is Gromov-hyperbolic. We also show that in typical situations, flaring is also a necessary condition.Comment: v3: Major revision: 56 pages 5 figures. Many details added. Characterization of convex cocompact subgroups of mapping class groups of surfaces with punctures in terms of relative hyperbolicity given v4: Final version incorporating referee comments: 63 pages 5 figures. To appear in Geom. Funct. Ana

Learning Trajectories in Mathematics: A Foundation for Standards, Curriculum, Assessment, and Instruction

Learning Trajectories in Mathematics: A Foundation for Standards, Curriculum, Assessment, and Instruction aims to provide: A useful introduction to current work and thinking about learning trajectories for mathematics education An explanation for why we should care about these questions A strategy for how to think about what is being attempted in the field, casting some light on the varying, and perhaps confusing, ways in which the terms trajectory, progression, learning, teaching, and so on, are being used by the education community. Specifically, the report builds on arguments published elsewhere to offer a working definition of the concept of learning trajectories in mathematics and to reflect on the intellectual status of the concept and its usefulness for policy and practice. It considers the potential of trajectories and progressions for informing the development of more useful assessments and supporting more effective formative assessment practices, for informing the on-going redesign of mathematics content and performance standards, and for supporting teachers’ understanding of students’ learning in ways that can strengthen their capability for providing adaptive instruction. The authors conclude with a set of recommended next steps for research and development, and for policy

Learning Progressions in Science: An Evidence-Based Approach to Reform

American education policy seems poised to escalate and shift its two decade long commitment to standards and outcome-based reform. That commitment has involved a set of “grand bargains”, in which the federal government provides Title I (The “No Child Left Behind Act” or NCLB) disadvantaged education funds in return for the states’ agreeing to set ambitious content standards, and define performance or “proficiency” standards associated with them that all students in the states’ schools will be expected to meet by the 2013/2014 school year. The disadvantaged children targeted by Title I are expected to meet the same standards as all of the rest of the children in each state. In return for agreeing to hold their schools accountable for meeting these expectations, the states are left free to set their standards and their related measures of proficiency as they wish, within some broadly defined parameters. And the local school systems and schools in each state, in return for their share of the Title I/NCLB money are left free, for the most part, to choose their preferred approaches to instruction as long as they agree to be held accountable for ensuring that all their students are making adequate progress towards meeting the state’s proficiency goals. So, the general form of each bargain is an agreement to reduce or forgo regulation of inputs in return for a commitment to define, and meet, outcome expectations. But, having agreed to do something they had never before tried to do—to succeed with essentially all students—schools and educators face the problem that they don’t know how to meet their side of the bargain. Proponents and observers of reform claim to be shocked that some states are setting their performance standards in ways that minimize or disguise the degree to which their students are likely to fail to meet the hopes of reform. In addition, schools and teachers are resorting to approaches, such as relentless test preparation and focusing on students who are just at the edge of meeting proficiency requirements, that try to meet the letter of the bargains’ requirements while leaving the more ambitious spirit of the reforms’ hopes well behind, along with all too many children

Barriers to mental health service use among distressed family caregivers of lung cancer patients

Although family caregivers of patients with lung and other cancers show high rates of psychological distress, they underuse mental health services. This qualitative study aimed to identify barriers to mental health service use among 21 distressed family caregivers of lung cancer patients. Caregivers had not received mental health services during the patient's initial months of care at a comprehensive cancer centre in New York City. Thematic analysis of interview data was framed by Andersen's model of health service use and Corrigan's stigma theory. Results of our analysis expand Andersen's model by providing a description of need variables (e.g. psychiatric symptoms), enabling factors (e.g. finances), and psychosocial factors associated with caregivers' non-use of mental health services. Regarding psychosocial factors, caregivers expressed negative perceptions of mental health professionals and a desire for independent management of emotional concerns. Additionally, caregivers perceived a conflict between mental health service use and the caregiving role (e.g. prioritising the patient's needs). Although caregivers denied stigma associated with service use, their anticipated negative self-perceptions if they were to use services suggest that stigma may have influenced their decision to not seek services. Findings suggest that interventions to improve caregivers' uptake of mental health services should address perceived barriers

Reduced Third Order Intermodulation Distortion Utilizing a Push-Pull Class C VHF Transistorized Amplifier

In a transistorized push-pull amplifier, third order intermodulation distortion was effectively reduced at VHF frequencies with an output power of two watt. The non-linear distortion of the amplifier is modeled using a power series. The resulting expression is used as the basis for choosing the push-pull configuration to reduce the third order intermodulation distortion. The amplifier was built and tested, and the experimental results compare favorably with the theoretical results. The level of the third order intermodulation distortion is found to be at least 30 dB below the interfering signal level

Relative Hyperbolicity, Trees of Spaces and Cannon-Thurston Maps

We prove the existence of continuous boundary extensions (Cannon-Thurston maps) for the inclusion of a vertex space into a tree of (strongly) relatively hyperbolic spaces satisfying the qi-embedded condition. This implies the same result for inclusion of vertex (or edge) subgroups in finite graphs of (strongly) relatively hyperbolic groups. This generalises a result of Bowditch for punctured surfaces in 3 manifolds and a result of Mitra for trees of hyperbolic metric spaces.Comment: 27pgs No figs, v3: final version, incorporating referee's comments, to appear in Geometriae Dedicat

The relationship between acceptance of cancer and distress: A meta-analytic review

Acceptance of cancer has long been recognized as playing a critical role in psychological adjustment to the illness, but its associations with distress outcomes have not been quantitatively reviewed. Informed by coping theory and third wave conceptualizations of acceptance, we first propose an integrated model of acceptance of cancer. Then we examine the strength of the relationships between acceptance of cancer and general and cancer-specific distress in cancer patients and potential moderators of these relationships. CINAHL, Embase, MEDLINE, PsycINFO, PsycARTICLES, and Web of Science databases were searched. Random-effects meta-analyses were conducted on 78 records (N = 15,448). Small-to-moderate, negative, and significant relationships were found between acceptance of cancer and general distress (r = −0.31; 95% CI: −0.36 to −0.26, k = 75); cancer-specific distress (r = −0.18; 95% CI: −0.21 to −0.14, k = 13); depressive symptoms (r = −0.25; 95% CI: −0.31 to −0.19, k = 41); and anxiety symptoms (r = −0.22; 95% CI: −0.30 to −0.15, k = 29). Age, marital status, and stage of cancer were identified as significant moderators. Findings suggest that acceptance of cancer may be important to target in interventions to reduce general and cancer-specific distress in cancer patients. Future research should focus on developing multifaceted measures of acceptance and identifying theory-based psychological and social processes that lead to greater acceptance