13,805 research outputs found

    Certain Body Temperature Changes in the Snapping and Painted Turtles

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    Experiments performed at Iowa Lakeside Laboratory during the past summer indicate that both forms show fluctuations of from 3 to 6 degrees F. in the so-called non-critical ranges of their environment (50-80 degrees F.). When subjected to a rapid environmental drop the rectal readings show a somewhat greater lag than when cooled more slowly. In both procedures a check in drop is noted at about 40 degrees F. (4.5 degrees C.) and there is maintained for a considerable interval of time

    Void Formation Study of Flip Chip in Package Using No-Flow Underfill

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    ©2008 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or distribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.DOI: 10.1109/TEPM.2008.2002951The advanced flip chip in package (FCIP) process using no-flow underfill material for high I/O density and fine-pitch interconnect applications presents challenges for an assembly process that must achieve high electrical interconnect yield and high reliability performance. With respect to high reliability, the voids formed in the underfill between solder bumps or inside the solder bumps during the no-flow underfill assembly process of FCIP devices have been typically considered one of the critical concerns affecting assembly yield and reliability performance. In this paper, the plausible causes of underfill void formation in FCIP using no-flow underfill were investigated through systematic experimentation with different types of test vehicles. For instance, the effects of process conditions, material properties, and chemical reaction between the solder bumps and no-flow underfill materials on the void formation behaviors were investigated in advanced FCIP assemblies. In this investigation, the chemical reaction between solder and underfill during the solder wetting and underfill cure process has been found to be one of the most significant factors for void formation in high I/O and fine-pitch FCIP assembly using no-flow underfill materials

    The Soviet Economy since Stalin

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    Making a Difference in Schools: The Big Brothers Big Sisters School-Based Mentoring Impact Study Executive Summary

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    Serving almost 870,000 youth nationwide, school-based mentoring is one of the fastest growing forms of mentoring in the US today. Making a Difference in Schools presents findings from a landmark random assignment impact study of Big Brothers Big Sisters School-Based Mentoring -- the first national study of this program model. This executive summary highlights nine key findings from the full report and outlines several recommendations for policy and practice

    Making a Difference in Schools: The Big Brothers Big Sisters School-Based Mentoring Impact Study

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    School-based mentoring is one of the fastest growing forms of mentoring in the US today; yet, few studies have rigorously examined its impacts. This landmark random assignment impact study of Big Brothers Big Sisters School-Based Mentoring is the first national study of this program model. It involves 10 agencies, 71 schools and 1,139 9- to 16-year-old youth randomly assigned to either a treatment group of program participants or a control group of their non-mentored peers. Surveys were administered to all participating youth, their teachers and mentors in the fall of 2004, spring of 2005 and late fall of 2005.The report describes the programs and their participants and answers several key questions, including: Does school-based mentoring work? What kinds of mentoring experiences help to ensure benefits? How much do these programs cost? Our findings highlight both the strengths of this program model and its current limitations and suggest several recommendations for refining this promising model-recommendations that Big Brothers Big Sisters agencies across the country are already working to implement
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