Feeder Areas Research Articles

Dark brooder pullets are less active than Non-brooder pullets, but show similar level of synchronisation at the resource areas

Maternal care in commercial chickens can partially be replaced with dark brooders that offer heat and a dark area to rest and possibly avoid negative social interactions. Previous research has established the positive effects of dark brooders on reducing disturbance during resting in young pullets and injurious pecking in pullets and laying hens, which could reduce overall activity levels. The objective of this study was to employ precision livestock farming techniques to compare the overall activity levels and behavioural synchrony at resources in pullets reared with dark brooders until 41 days of age and those reared with whole house heating. Four brooder treatments, varying in size (Small/Large) and deployment method (Raised/Fixed), which could have implications for commercial use, were employed. Activity of the whole pen floor area and behavioural synchrony in drinker and feeder areas were automatically assessed over a 12-hour photoperiod at 10 and 60 days of age. Pixel change detection gauged overall activity across the pen, while an object detection model evaluated pullet behavioural synchrony. The analysis revealed increased activity levels in non-Brooder pullets compared to those in most Brooder treatments at both 10 and 60 days of age. However, no significant differences in behavioural synchrony were observed between Brooder and non-Brooder pullets. The underlying mechanism of dark brooder’s effects on the activity levels and behaviour synchrony remains unclear, but the observed reduction in activity levels in brooded pullets likely corresponds to increased resting behaviour and reduced injurious pecking. Furthermore, it is noteworthy that only a small percentage of pullets (up to 57.14%) were observed to use the resources simultaneously. This underscores the importance of conducting additional research to delve into the effects of resource allocation on both behavioural synchrony and activity levels in pullets. We observed minimal differences in the behaviour of pullets raised under different brooder types, suggesting that the simplest (Small-Fixed) brooders may be suitable for commercial use.

Determining a Key Service Area of Feeder Buses for Rail Transit Station Based on Potential Railway Demand

As the size of the city expands, longer journeys often involve the use of two or more modes of transportation. Feeder buses perform as a feeder mode of rail transit, its feeder areas are the key factor to improve this bus-rail transit mode service quality. Feeder areas that are either too small or too large can hinder the effectiveness of feeder buses. This paper presents a method to determine a suitable range as the key service of feeder buses for rail transit stations. The modal of accessibility consistency threshold interface of bus and bus-rail transit mode features is established, and the competition area of adjacent stations is considered to calculate the reasonable bus feeder range of rail transit stations. Based on the analysis of the demand characteristics of the feeder passengers, the potential passengers of the bus-rail transit travel mode are defined as the travel where only one endpoint of the starting and ending is within the walking range of the rail transit station, and a method for identifying the points of interest of potential passengers of the bus-rail transit mode is proposed. The potential passenger flow within the reasonable feeder range of rail transit stations is visualized, and the key service areas of feeder buses are determined based on the maximum potential passengers. Taking Jinan Metro Line NO.2 Stations as an example, combined with the station type, the key service area of feeder buses for railway stations is explained.

Accuracy of Broiler Activity Index as Affected by Sampling Time Interval.

Simple SummaryBroiler activity index is a measure of bird movement through determining bird-representative pixel changes between consecutive images. Since the concept of activity index was coined, different sampling time intervals of consecutive images have been used to determine broiler activity. In this study, we found that accuracy of broiler activity decreased at longer sampling time intervals, with the 0.04-s interval yielding the most accurate activity index among all intervals investigated. In addition, broiler activity in the commercial house generally decreased as birds aged and varied at different monitoring locations. The research provides insights into image-sampling strategies for accurately determining broiler activity index, which may help to address growing public concerns on poultry welfare and health. Different time intervals between consecutive images have been used to determine broiler activity index (AI). However, the accuracy of broiler AI as affected by sampling time interval remains to be explored. The objective of this study was to investigate the effect of the sampling time interval (0.04, 0.2, 1, 10, 60, and 300 s) on the accuracy of broiler AI at different bird ages (1–7 weeks), locations (feeder, drinker, and open areas) and times of day (06:00–07:00 h, 12:00–13:00 h, and 18:00–19:00 h). A ceiling-mounted camera was used to capture top-view videos for broiler AI calculations. The results show that the sampling time interval of 0.04 s yielded the highest broiler AI because more bird motion details were captured at this short time interval. The broiler AIs at longer time intervals were 1–99% of that determined at the 0.04-s interval. The broiler AI at 0.2-s interval showed an acceptable accuracy with 80% less computational resources. Broiler AI decreased as birds aged but increased after week 4 at the drinker area. Broiler AI was the highest at the open area for weeks 1–4 and at the feeder and drinker areas for weeks 5–7. It is concluded that the accuracy of broiler AI was significantly affected by sampling time intervals. Broiler AI in commercial housing showed both temporal and spatial variations.

Origin of placer gold and other heavy minerals from fluvial Cenozoic sediments in close proximity to Rote Fäule-related Au mineralisation in the North Sudetic Trough, SW Poland

Detailed morphological and geochemical studies of placer gold grains and other heavy minerals from Cenozoic fluvial clastic sediments in the area of the Zimnik Creek drainage basin (North Sudetic Trough, Lower Silesia) allowed the description of their specific features: shape and morphology, flatness index, internal textural features and chemical composition of the gold grains. It enables an estimation of the distance from the source area and determination of the source of the ore mineralisation, along with establishing the feeder areas for placer mineralisation including Rote Faule-related gold hosted by Rotliegend-Zechstein transitional sediments. The comparison of the heavy mineral contents of placer grains from the Zimnik Creek drainage basin makes it possible to identify the area of origin for the gold particles. The crystalline Au-Ag-Pd-Hg (polymetallic) alloy grains of fluvial gold are assumed to come from the transitional sediments between the Rotliegend and the Zechstein in the North Sudetic Basin. The morphological and geochemical features of the polymetallic grains strongly suggest that the grains from the upper course of the Zimnik Creek valley sediments represent what has eroded from the local gold mineralisation and this mineralisation is probably in the vicinity of the upstream sampling site. The bimodal chemical composition of the Au-Ag-Pd-Hg alloy grains with electrum and medium-Ag grains (<15 wt.% Ag) found in the study area is typical of the Rote Faule and Kupferschiefer-related gold mineralisation on the southern side of the North Sudetic Trough and the Sieroszowice-Polkowice copper mining district of the Fore-Sudetic Monocline. The study of the Ag contents of placer grains from the Zimnik Creek drainage basin highlights the contrast between the placer gold grains derived from Paleozoic orogenic gold mineralisation in the Sudetes (typically simple Au-Ag alloys containing between 5 and 20 wt.% of Ag) and the one formed by the oxidizing chloride hydrothermal systems. The grains identified in this manner as originating from the oxidizing hydrothermal system of the transitional zone can be distinguished from the placer gold derived from other styles of mineralisation, which are not Rote Faule-related. It is particularly important considering the ongoing reconnaissance exploration in the North Sudetic Trough (SW Poland), which employs gold grain analyses as a prospecting tool for the detection of potentially economic primary gold mineralisation.

Management Practices Affect Soil Nutrients and Bacterial Populations in Backgrounding Beef Feedlot.

Contaminants associated with manure in animal production sites are of significant concern. Unless properly managed, manure-derived soil nutrients in livestock production sites can deteriorate soil and water quality. This 3-yr study evaluated a soil nutrient management strategy with four sequentially imposed management practices: 12-mo backgrounding (BG), manure removal from the feeder area (FD), 12-mo destocking (DS), and 12-mo grass hay harvesting (H) in a small backgrounding feedlot. Resulting soil nutrient levels, total (), and N cycling bacterial ( and ) populations after each management practice in feedlot feeder and grazing (GR) areas and in crop grown at the control location (CT) were measured. Irrespective of management practice, FD contained greater soil nutrient concentrations than the GR and CT. Regardless of management practice, total bacteria cells (1.4 × 10 cells g soil) and nitrate reducers (5.2 × 10 cells g soil) were an order of magnitude higher in the FD than in the GR and CT, whereas nitrifying bacteria concentrations (1.4 × 10 cells g soil) were higher in the GR. Manure removal from the feeder area reduced M3-P (39%), total C (21%), total N (23%), NH-N (47%), and NO-N (93%) levels established in the FD during BG. Destocking lowered total C and N (45%) in the FD and NH-N (47%), NO-N (76%), and Zn (16%) in the GR. Hay harvesting reduced all soil nutrients in the FD and GR marginally. The management strategy has potential to lower soil nutrient concentrations, control soil nutrient buildup, and limit nutrient spread within the feedlot.

English

&nbsp; Education is a very important factor of human resource development and management. After a long period of independence, our nation is yet to achieve desired level of education. This is&nbsp; worst in tribal societies. Tribes are the primeval communities that constitute a considerable proportion of national population. Each of the tribal communities has its own cultural identity. But in general they are very poor. Educational backwardness lies at the root of their economic, social and political backwardness. The District of Paschim Medinipur is situated at the Western margin of West Bengal and a vast area of this district is mostly inhabited by tribes, especially the Santhal Community. The present paper seeks to assess the status of educational attainment of tribal students. The study was conducted in some tribal dominated schools of Paschim Medinipur District with the help of questionnaire survey and secondary data collected from the schools and Secondary Education Department, Government of West Bengal. The study identifies some reasons behind the poor level of academic achievement among the tribal students. It has been found that, most of the schools are disadvantaged because they have very poor infrastructural facilities. The schools have very poor student-teacher ratio and classroom-pupils ratio. Most of them have no library rooms and well maintained playgrounds. Moreover, toilets and lavatories are poorly maintained. The schools have very large feeder areas. Therefore, students are to move a large distance to reach their schools. In most of the Gram Panchayat areas there are very few numbers of higher schools in comparison to the number of lower and primary schools. That is one of the reasons why the rate of drop out is found to be very high for the tribal students. Though the students are very obedient, diligent, physically sound and have many good habits, they perform very poor in academics.&nbsp; &nbsp; Key words:&nbsp;Tribes, education, success, dropout, enrollment, feeder area, Lorenz Curve, educational status, educational profile, educational infrastructure, Santhal, West Bengal, Jungle mahal. &nbsp; &nbsp; &nbsp

Spatial Variation in School Performance, a Local Analysis of Socio-economic Factors in Cape Town

Poor pass rates of matric learners at secondary schools in South Africa has been a concern for quite some time. Despite large government spending on education, research has shown that the South African schooling system is struggling to convert resources to student performances and failing to promote social equity. The poor performance by South African students prompts further investigation into the factors contributing to educational outputs. The focus of this case study in Cape Town is twofold, firstly to determine if there are any spatial patterns among the matric pass rates of secondary schools and secondly to determine if there are any relationships between the matric pass rate of the school and the socio-economic attributes of the school feeder areas. Key findings of this research suggest that Cape Town schools are clustered in terms of school performance with high performing schools grouped together and many low performing schools also clustered together. There were a few exceptions where within a cluster of low performing schools there was one high performing school and vice versa. Outcomes of the research into spatially varying relationships point to selected socio-economic factors of the community, particularly parent and household characteristics, influencing the learner’s school performance. Key words: Matric pass rate, school performance, spatial analysis, socio-economic factors, spatial relationships

Urination and defecation by group-housed dairy calves

A better understanding of when and where group-housed calves are most likely to defecate or urinate might permit improved housing design or more efficient use of cleaning routines. However, this is the first study to address the urination and defecation habits of calves. The primary aims of this study were to report the daily frequency of calves’ urination and defecation and determine when and where group-housed dairy calves defecate and urinate most frequently. We were also interested to see if incidence of urination and defecation changed with increasing age and the change in diet at weaning. We observed 36 female Holstein calves, housed in groups of 9, and fed milk, grain, and hay from automated feeders. For the purposes of another experiment, these calves were assigned to 1 of 3 experimental treatments relating to age at start of weaning and milk allowance: low milk allowance and early weaning (6 L/d, 42d), high milk allowance and early weaning (12 L/d, 42d), and high milk allowance and late weaning (12 L/d, 84d) The occurrence of defecations and urinations was determined by continuous observation of video recordings taken over 72h at 2 age periods (age, mean ± SD; period 1=32.0±11.13d and period 2=61±11.29d). Due to the treatments, weaned and unweaned calves were observed in each period (period 1: 34 unweaned and 2 weaned calves; period 2: 16 unweaned and 20 weaned calves). Large differences were found between calves in mean daily frequency of total urinations and defecations across a 3-d period (mean=17.56±5.07/d, range=4.33 to 28.67). Differences between individual calves did not change significantly over time, provided calves remained unweaned. Two days of observation was sufficient to give a reliable estimate of daily urination and defecation frequency. Frequency of urination and defecations was higher in calves postweaning. Higher age and visits to the milk feeder were associated with a higher frequency of urinations and defecations preweaning. After weaning, frequency of eliminations increased with increasing visits to the water feeder. An effect of time of day was observed, with significantly more events during daylight hours (0600–1800h) in comparison to night (1800–0600h). Before weaning, calves urinated and defecated significantly more on slatted flooring and sawdust-bedded areas than within the feeder (daily mean ± SD=6.96±3.15, 6.49±3.90, and 4.10±2.67 for slatted floor, bedded floor, and feeder areas, respectively). Frequency of eliminations in feeders and slatted, but not sawdust-bedded, areas was higher in calves postweaning. Calves urinate and defecate more frequently during daylight hours when they are more active. Slatted flooring around feeders is useful to reduce soiling of bedded areas, particularly as calves increase in age.

The method of the correlation and dispersion defining of the total power components in the electric transport devices

Purpose. Development and theoretical ground of the analytical method for the calculation of the active, reactive and total powers in the electric traction devices, taking into consideration the non-stationary character of the stochastic processes change of the voltage and current in the elements of these systems. Methodology. The mathematical methods of the random processes theory and the “discrete electrical engineering” methods are used for solving the main problem of this paper. Findings. The Method of the Correlation and Dispersion is developed for definition of the active power, the reactive power by Fryse and the total power of the devices in the elements of the electric traction system of the main-line railways. The method is based on the well-known concepts of auto- and inter-correlation functions of the random processes which govern the feeder voltages and the currents in the traction power supply subsystem as well as the currents and voltages of the electric rolling stock. The method developed in this paper allows estimating the powers of both stationary and non-stationary processes. This method can be used for the analysis of both the traction mode and the regenerative braking mode of the electric rolling stock. The total power components were calculated for the one of the feeder areas of the Prydniprovsk railway using this method. The results show the significant flow of the reactive power in the traction power supply system. This fact is also confirmed by the high values of the reactive power coefficient. Originality. Scientific novelty of the research is consisted in the following. Firstly, for defining the active and reactive powers in elements of the traction power supply system the new method (the Method of Correlation and Dispersion) is created and grounded. This method is different from other existing methods because it takes into consideration the varying non-stationary character of the chance processes of the feeder and substation voltages and currents. Secondly, in the DC traction power supply system the large values of the exchange reactive power by Fryze were created for the first time. Practical value.The method and its technique allow calculating the main energy coefficients for the traction power systems such are the reactive power coefficient, the main and additional active power losses in the power circuit of the electric rolling stockand the traction power supply system.

Soil Nutrients, Bacteria Populations, and Veterinary Pharmaceuticals across a Backgrounding Beef Feedlot

Beef cattle backgrounding operations that grow out weaned calves for feedlot finishing contain several environmentally significant constituents. A better understanding of these constituents and their environmental distribution will aid in the development of effective management guidelines for sustainable beef production. This research investigated soil nutrients, bacterial, and veterinary pharmaceutical concentrations across a small backgrounding beef feedlot on a karst landscape. Results indicated that all contaminants were highly concentrated in the feeder area (FD) and were lower in the other feedlot areas. The FD soils had a pH of 8.2, 59 mg kg soil organic matter (SOM), 2002 mg kg soil test phosphorus (STP), 99.7 mg kg NH-N, and 18.3 mg kg NO-N. The other locations were acidic (5.9-6.9 pH) and contained 39 mg kg SOM, 273 mg kg STP, 21.5 mg kg NH-N, and 2.0 NO-N mg kg. Bacteria populations in the FD averaged 2.7 × 10 total cells, 3.9 × 10 spp., 2.9 × 10 spp, and 4.5 × 10 cells per gram of soil. spp. and spp. concentrations were 1 to 4 orders of magnitude lower at the other locations. showed lower dynamic range and was generally uniformly distributed across the landscape. Antibiotic and parasiticide concentrations in the FD were 86.9 ng g monensin, 25.0 ng g lasalocid, and 10.3 ng g doramectin. Their concentrations were 6- to 27-fold lower in the other feedlot locations. Contaminant management plans for this small feedlot will therefore focus on the feeder and nearby grazing areas where soil nutrients, bacteria populations, and veterinary pharmaceuticals were most concentrated.

Non-productive losses of electric power in the networks of traction power supply of main railways

A new method of correlation functions, determinations of power indexes and nonproductive (additional) losses of electric power in the traction electric systems of direct-current have been suggested. Non-productive losses have been calculated for a number of feeder areas. It has been shown that these losses are 6…15% of electric power consumed by electric train.

Source-to-sink relationships along the South-Central Chilean margin: evidence from detrital apatite fission-track analysis

Detrital fission-track studies on sedimentary basins surrounding eroding mountain belts provide a powerful tool to reconstruct exhumation histories of the source area. However, examples from active arc-trench systems are sparse. In this study, we report detrital apatite fission-track (AFT) data from Holocene and Pleistocene turbiditic trench and modern river sediments at the Chilean margin (36°S-47°S). Sediment petrography and detrital AFT data point to different major sediment sources, underlining the need for multidisciplinary studies: whereas sediment petrography indicates the erosion of large volumes of volcanic detritus, no such volcanic signal is seen in the detrital age pattern. Areally subordinate plutonic units are identified as the main, often unique sources. This result has important implications for studies of fossil systems, where the feeder areas are eroded, and where the youngest age population is often interpreted to indicate active volcanism. For the southernmost part of the study area in the Patagonian Andes, where the source area is mainly composed of granitoids, the sediment is derived from only small portions along the main divide, pointing to focused glacial erosion there. Our detrital AFT data show no exhumational signal that could be related to the subduction of the actively spreading Chile Ridge at c. 47°S and to the opening of a slab window beneath the South American Plate.

Studying together, living apart: Emerging geographies of school attendance in post-apartheid Cape Town

Studying together, living apart: Emerging geographies of school attendance in post-apartheid Cape Town

Determination of Feeder Areas for the Design of Large Distribution Networks

One of the methods for setting distribution tariffs is benchmarking competition. In Chile, a yardstick competition scheme is applied. This yardstick consists of a “model company” that is designed in order to quantify what would be the least cost of operating an efficient distribution company serving the same demand as the actual company. Input data for the design of the company's network are load locations, magnitudes, and growth forecast, and feasible feeder routes. The design of this network, considering its high combinatorial degree, size, and operational constraints, is a difficult task and it is known to be an NP hard problem. In this paper, a new approach is presented where the problem is separated by feeder areas. The criterion used for dividing the areas is to maintain an equitable distribution of loads among them. Two methodologies are compared for area dimensioning: 1) Voronoi tessellation and 2) k-means clustering. Once the feeder areas are defined, the network is designed by applying a genetic algorithm based on the generation of spanning trees. Finally, in order to fulfill real operational constraints, it is considered that all of the feeders share the same output from the substation. This is achieved by using an algorithm that identifies shared routes and performs the final step of the design of the system.

Which dairy calves are cross-sucked?

We examined which calves within a group were the recipients of cross-sucking, whether this was related to body weight or feeding behaviour, and whether cross-sucking served to displace calves from the feeders. Forty-five Holstein dairy calves housed in groups of nine and fed by computer-controlled feeders were used. Calves were fed either 6 L/d or 12 L/d of milk and gradually (over 9 d) weaned off milk either by d47 or d89. Cross-sucking was recorded continuously for 12 h/d on 2 d at approximately 37 d, 47 d, 79 d and 89 d of age. Data on feeding behaviour were collected automatically by the feeders. There were large differences between calves in the duration of time being cross-sucked. There was a moderate positive correlation across calves in the duration of being cross-sucked and the duration of cross-sucking another calf. The top quartile of calves that were cross-sucked accounted for 68% of the total duration of cross-sucking. These calves had significantly higher bodyweights and spent more time in the milk feeders than the lowest quartile at most ages, but no difference was found in the time spent in the starter feeders. The calves were most often cross-sucked in the sawdust-bedded area at d37 and d47 and in the feeder areas at d79 and d89, but only a minority of cross-sucking occurred while the calf was actually in a feeder. In 80% of the episodes of cross-sucking that occurred when the recipient was in a feeder, the receiver remained in the feeder. Cross-sucking rarely resulted in a calf being displaced from a feeder. We concluded that larger calves that spend more time in the feeders seem to be at a higher risk for being cross-sucked but that cross-sucking does not serve to displace animals from the feeders.

Overcoming The Apartheid Legacy In Cape Town Schools*

ABSTRACT. Restructuring apartheid geographies of racial stratification and spatial segregation poses formidable challenges, not least in education. Increasing intraracial inequality also underscores the importance of widening access and opportunity. Although South African education is not constrained by the highly localized control found in the United States and the United Kingdom, school allocation policies and parental choices create geographies that intersect with those of race and residence. Spatial variations critically influence both the impacts of postapartheid policies and the patterns of school desegregation. In this article we explore the spatial impact of inequality, desegregation, and state policies in relation to fourteen secondary schools in Cape Town, distinguishing outcomes that reflect inherited inequalities and current policies from outcomes that reflect individual school strategies. Capital funding is insufficient to change inherited inequalities, and differential fees and fund‐raising capacities perpetuate inequalities in operational resources. Sharing resources, taxing fee income, and a measure of provincial control over feeder areas could reduce inequalities.

Redressing School Inequalities in the Eastern Cape, South Africa

Education is a critical element in post-apartheid restructuring. In 1994 the ANC-led government inherited a racially divided and discriminatory education system to which the National Party had, in its early 1990s reforms, added elements of a market-driven system. National policies since 1994 have been rich in the political symbolism of equity and redress, but in practice were characterised by acceptance of commodification and choice and very limited implementation of change on the ground. This article explores these themes using fieldwork carried out in the Eastern Cape. Provincial information is based on documentation and data supplied by the Provincial Education Department and the Examinations Centre, supplemented by interviews. Detailed research was carried out in and around Grahamstown, visiting fifteen schools ranging from exclusive private schools to those in townships, informal settlements and rural areas. Desegregation and redistribution are explored in relation to parental incomes, fees and school feeder areas; parental choice of schools and involvement in governing bodies; learner:teacher ratios and teacher redeployment; resource constraints, buildings and facilities, books and materials; relationships between schools and provincial authorities; examination results; and relations between resource-rich and resource-poor schools. Provincial funding levels cover little beyond the salaries of approved numbers of teachers, leaving most other expenditure dependent on fee income and funds raised by other means. Class rather than race is now the main determinant of educational opportunity. For the poor majority, the system offers neither equality of opportunity nor significant redress to compensate for the injustices of apartheid education. Some directions for changing policy and practice are suggested.

Role of venous drainage in cerebral arteriovenous malformation surgery, as related to the development of postoperative hyperperfusion injury.

To elucidate the role of venous drainage in cerebral arteriovenous malformation (AVM) surgery, with respect to the development of postoperative hyperperfusion injury. For 52 patients with supratentorial AVMs, cortical capillary oxygenation (SaO(2)) was assessed intraoperatively, before and after resection, in the vicinity of the AVMs, by using a microspectrophotometric method. Assessed areas were defined as being related to feeding arteries or draining veins or as distant areas. Patients were divided into three groups on the basis of postoperative angiographic findings, as follows: Group 1, all former draining veins preserved (8 patients); Group 2, > or =1 former draining vein visible (12 patients); Group 3, no former draining veins visible (32 patients). Patients and SaO(2) values were pooled and compared by using paired and unpaired t tests (P < 0.05). Venous circulation times were calculated from digital subtraction angiography films. The postresectional relative increases in SaO(2) values were highest in draining vein areas (+40.8%, compared with +25% in feeder areas and +25.5% in distant areas). Five postoperative hyperemic complications occurred (9.6%), none in Group 1 (with all draining veins preserved), two (16.7%) in Group 2, and three (9.4%) in Group 3 (with all draining veins occluded). The lowest preresectional SaO(2) values (31.7 +/- 6.2%) were measured in the drainer areas of the five patients who subsequently developed hyperperfusion injuries. Among those patients, postresectional increases in SaO(2) values were significantly greater in drainer areas (+167.8%) than in feeder areas (+28.3%) or distant areas (+25.8%). Postoperative venous circulation times in former draining veins in Group 2 were significantly greater than those in Group 1 (8.9 +/- 1.5 s versus 6.3 +/- 0.6 s). Circulation times in normal veins in the five patients with hyperperfusion injury increased from 5.6 +/- 1.0 seconds (preoperatively) to 8.4 +/- 1.9 seconds (postoperatively). Postoperative hyperperfusion injury after resection of cerebral AVMs can be explained on the basis of unconstrained arterial inflow into cortical areas, which are rendered hypoxic/ischemic by longstanding preoperative venous hypertension. The risk for postoperative breakthrough complications seems higher in the presence of multiple draining veins, which also participate in the physiological venous drainage system of the ipsilateral hemisphere.

Winter Survival and Territory Acquisition in a Northern Population of Black-Capped Chickadees

Abstract We assessed the effects of winter food supplementation on differential survival between sex, age and dominance classes, and the effects of feeding and territorial defense on breeding density in a northern population of Black-capped Chickadees (Parus atricapillus). Survival rates were higher in a food-supplemented area than in a control area, which suggests that food abundance limited winter survival. Survival was greater among males than lower-ranking females in 1 of 2 years, and greater in dominants than in subordinates, within sex and age classes. Survival of adults and first-year birds, however, did not differ significantly. In the 2 years of this study, a sharp decline of population size occurred at the onset of territoriality in spring. Birds that disappeared in spring were mainly subordinates of each sex. Breeding densities in control and feeder areas were similar in the two years. Eight of 14 territorial birds removed in 2 years were replaced, implying that a nonbreeding surplus was present in early spring.

Results of monitoring of noise and air quality in feeder areas at various proximities to freeways for matched groups of school children

Community noise levels throughout feeder areas serving 16 grammar schools in the Los Angeles County School District were monitored in order to determine the environmental noise exposure experienced by 3rd and 6th graders in socioeconomically matched groupings. Schools for this study were selected such that the noise environments for one‐half of the feeder areas would be largely controlled by freeway traffic noise. Noise monitoring at school sites within each feeder area was also conducted. Additionally, indoor and outdoor air quality monitoring was conducted on a rotational basis during December 1978 and January 1979 at each school site. Estimates of each feeder area's relative air quality have been extrapolated from the school studies which were in turn correlated to South Coastal Air Basin air quality data. Community noise levels, based upon approximately 350 site days of monitoring, are presented along with each feeder area's socioeconomic and ethnic population descriptors. The influence of freeway proximity on environmental noise levels and ambient air quality is discussed.