A study of twenty-five boys referred to the citizenship training department of the Boston Juvenile Court in the year 1949

Thesis (M.S.)--Boston Universit

Scanning Electron Microscopic Observation of Dark Cells After Streptomycin Perfusion of the Vestibule in Guinea Pigs

Hearing has been stabilized in the majority of patients studied in the treatment of Meniere\u27s disease with streptomycin. This observation suggests that effects of streptomycin may ameliorate endolymphatic hydrops, possibly by attenuating the activity of secretory tissue. The purpose of this study is to observe the dark cells of the utricle in guinea pigs after streptomycin perfusion of the vestibule. Twelve pigmented guinea pigs weighing 250-350 grams were used in this study. The vestibules in five guinea pigs were perfused monolaterally with 150 μg of streptomycin in artificial perilymph and, in seven, the vestibules were perfused only with artificial perilymph as a control group.Specimens were processed for observation with a scanning electron microscope. After streptomycin perfusion, the margin of the dark cells became indistinct. The luminal surface of the cells bulged out like a dome. The microvilli decreased or were absent, and some debris was deposited on the surface. In four of the five animals, the luminal membrane of the dark cell ruptured. The cytoplasm and organelle extruded into the endolymphatic space. After the cellular debris moved out into the endolymph, either a vanished cell or a nucleus in an empty nest was observed. These cells appeared damaged and destroyed. The results indicate that the dark cells in the membranous wall of the utricle were affected by streptomycin. The results lead to the assumption that streptomycin may reduce the volume of endolymph by damaging the dark cells of the utricle

The African Origin of Complex Projectile Technology: An Analysis Using Tip Cross-Sectional Area and Perimeter

Despite a body of literature focusing on the functionality of modern and stylistically distinct projectile points, comparatively little attention has been paid to quantifying the functionality of the early stages of projectile use. Previous work identified a simple ballistics measure, the Tip Cross-Sectional Area, as a way of determining if a given class of stone points could have served as effective projectile armatures. Here we use this in combination with an alternate measure, the Tip Cross-Sectional Perimeter, a more accurate proxy of the force needed to penetrate a target to a lethal depth. The current study discusses this measure and uses it to analyze a collection of measurements from African Middle Stone Age pointed stone artifacts. Several point types that were rejected in previous studies are statistically indistinguishable from ethnographic projectile points using this new measure. The ramifications of this finding for a Middle Stone Age origin of complex projectile technology is discussed

The Evolution of Endurance Running and the Tyranny of Ethnography: A Reply to Pickering and Bunn (2007)

Endurance running (ER) poses a conundrum for paleoanthropologists. As summarized in Bramble and Lieberman (2004), human ER capabilities, which are unique among primates, either match or exceed those of mammals adapted for running (cursors), including dogs and equids. Because many of the biomechanical and physiological challenges of human ER are so different from those of walking, we can conclude that human ER capabilities did not arise merely as a by-product of selection for walking. Instead, the available evidence suggests that an array of features that improve ER performance were selected in the genus Homo, and they were probably present to some extent by the appearance of Homo erectus at approximately 1.9 Ma. Yet, ER is no longer necessary for human survival, even among extant foragers such as the Hadza or the Bushmen. Thus, a puzzle that paleoanthropologists must solve is identifying what past behaviors - behaviors no longer common among living foragers - favored the evolution of ER. Pickering and Bunn’s (2007) criticisms of the ER hypothesis center on two issues: first, that early Homo lacked the tracking abilities necessary for successful pursuit hunts, and second, that recent ethnographic evidence suggests that modern hunter-gatherers rarely use ER to either hunt or scavenge. These arguments are based on a presumptive link between modern human- like cognition and tracking abilities, as well as the notion that the modern ethnographic record provides an adequate reflection of past behaviors. Both of these assumptions are flawed. Although tracking is complex, there is little evidence to suggest that early hominids lacked the tracking abilities of much less encephalized carnivores. Additionally, as noted by Marlowe (2005), comparatively recent inventions, such as the bow and arrow, the spear thrower, nets, and even the spear point, fundamentally altered how humans hunt and scavenge. A strict reliance on the recent ethnographic record, what Wobst (1978) termed the ‘‘tyranny of ethnography,’’ is a fundamentally problematic way of testing hypotheses of past hunting behavior. Even so, a review of the ethnographic evidence reveals errors in Pickering and Bunn’s contentions.Anthropolog

Identifying causes for certain types of electrically initiated fires in residential circuits

Abstract -While there are many circumstances that can lead to an electrical fire, it is helpful to identify and document known hazardous conditions that can occur in residential electrical wiring. Conditions that can be reproduced in a laboratory, intended to duplicate real-life conditions, can be used to increase knowledge for augmenting fire forensics and as a guide for manufacturers to develop safer, more fire resistant electrical systems. Failure modes for a variety of situations are described along with electrical data, photos, and video frames to show the conditions that produced a hazardous condition. Generally, the electric current produces an overheated condition in the presence of some type of combustible material. This work identifies some of the various conditions that can create the hazardous conditions and shows how wire insulation or other insulating materials, commonly used in homes, can ignite. Fires can initiate simply from exceeding the current rating of the wire or by having the wire bundled or having thermal insulation surround the wire. The types of cases explored include bundled extension cords under rugs and NM-B at the load center entrance with thermal insulation covering the wire. Other potential electrical fire hazards can be caused by broken wires or loose connections that lead to arcing or overheating. Loose wires, especially at an outlet fixture, can create glowing or overheated connections. A study of glowing connections will be presented along with overheating of PVC wiring due to series arcs. Low and high current arc energies will be discussed and compared to the combustible energy of volatile gases produced from wire insulation to illustrate the wide difference in the arc energy compared to chemical combustion energy from the decomposed PVC. Electrical wire insulation properties were also measured on various wire types to show the effects of thermal aging. Hardness of the wire insulation and cracking of the insulation was used as a measure of lifetime at 140 o C. Extrapolation to lower temperatures is described

Report of the committee on a commercially developed space facility

Major facilities that could support significant microgravity research and applications activity are discussed. The ground-based facilities include drop towers, aircraft flying parabolic trajectories, and sounding rockets. Facilities that are intrinsically tied to the Space Shuttle range from Get-Away-Special canisters to Spacelab long modules. There are also orbital facilities which include recoverable capsules launched on expendable launch vehicles, free-flying spacecraft, and space stations. Some of these existing, planned, and proposed facilities are non-U.S. in origin, but potentially available to U.S. investigators. In addition, some are governmentally developed and operated whereas others are planned to be privately developed and/or operated. Tables are provided to show the facility, developer, duration, estimated gravity level, crew interaction, flight frequency, year available, power to payload, payload volume, and maximum payload mass. The potential of direct and indirect benefits of manufacturing in space are presented

The Momentum of Human Behavior in a Natural Setting

Adults with mental retardation in a group home received popcorn or coffee reinforcers for sorting plastic dinnerware. In Part 1 of the experiment, reinforcers were dispensed according to a variable-interval 60-s schedule for sorting dinnerware of one color and according to a variable-interval 240-s schedule for sorting dinnerware of a different color in successive components of a multiple schedule. Sorting rates were similar in baseline, but when a video program was shown concurrently, sorting of dinnerware was more resistant to distraction when correlated with a higher rate of reinforcement. In Part 2 of the experiment, popcorn or coffee reinforcers were contingent upon sorting both colors of dinnerware according to variable-interval 60-s schedules, but additional reinforcers were given independently of sorting according to a variable-time 30-s schedule during one dinnerware-color component. Baseline sorting rate was lower but resistance to distraction by the video program was greater in the component with additional variable-time reinforcers. These results demonstrate that resistance to distraction depends on the rate of reinforcers obtained in the presence of component stimuli but is independent of baseline response rates and response-reinforcer contingencies. Moreover, these results are similar to those obtained in laboratory studies with pigeons, demonstrating that the determination of resistance to change by stimulus-reinforcer relations is not confined to controlled laboratory settings or unique to the pigeon

Factors influencing place of delivery for women in Kenya: an analysis of the Kenya Demographic and Health Survey, 2008/2009

Background Maternal mortality in Kenya increased from 380/100000 live births to 530/100000 live births between 1990 and 2008. Skilled assistance during childbirth is central to reducing maternal mortality yet the proportion of deliveries taking place in health facilities where such assistance can reliably be provided has remained below 50% since the early 1990s. We use the 2008/2009 Kenya Demographic and Health Survey data to describe the factors that determine where women deliver in Kenya and to explore reasons given for home delivery. Methods Data on place of delivery, reasons for home delivery, and a range of potential explanatory factors were collected by interviewer-led questionnaire on 3977 women and augmented with distance from the nearest health facility estimated using health facility Global Positioning System (GPS) co-ordinates. Predictors of whether the woman’s most recent delivery was in a health facility were explored in an exploratory risk factor analysis using multiple logistic regression. The main reasons given by the woman for home delivery were also examined. Results Living in urban areas, being wealthy, more educated, using antenatal care services optimally and lower parity strongly predicted where women delivered, and so did region, ethnicity, and type of facilities used. Wealth and rural/urban residence were independently related. The effect of distance from a health facility was not significant after controlling for other variables. Women most commonly cited distance and/or lack of transport as reasons for not delivering in a health facility but over 60% gave other reasons including 20.5% who considered health facility delivery unnecessary, 18% who cited abrupt delivery as the main reason and 11% who cited high cost. Conclusion Physical access to health facilities through distance and/or lack of transport, and economic considerations are important barriers for women to delivering in a health facility in Kenya. Some women do not perceive a need to deliver in a health facility and may value health facility delivery less with subsequent deliveries. Access to appropriate transport for mothers in labour and improving the experiences and outcomes for mothers using health facilities at childbirth augmented by health education may increase uptake of health facility delivery in Kenya