bluuebunny/crossref_metadata_2025 huggingface dataset:
Biomechanical, histological and ultrastructural analyses of laser micro‐ and nano‐structured titanium implant after 6 months in rabbit
Authors: Palmquist Anders , Emanuelsson Lena , Brånemark Rickard , Thomsen Peter
Published: March 2011

Short‐term, experimental studies of partly laser‐modified implants with nano‐scale surface topographical features have recently shown a considerable increase in the biomechanical anchorage to bone. The aim of this study is to evaluate the biomechanical and bone‐bonding ability of partly laser‐modified implants compared with machined implants after a healing period of 6 months in a rabbit model. The results showed a 170% increase in removal torque. Histology and scanning electron microscopy demonstrated osseointegration for both implant types, but also revealed a different fracture pattern at the interface and in the bone. Transmission electron microscopy and chemical analysis showed coalescence between mineralized tissue and the nano‐structured surface of the laser modified implant. Taken together, the results indicate that nano‐structured surfaces promote in vivo long‐term bone bonding and interface strength. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Determination of the antiretroviral drug tenofovir in plasma from HIV‐infected adults by ultrafast isotope dilution MALDI‐triple quadrupole tandem mass spectrometry
Authors: Meesters Roland J. W. , van Kampen Jeroen J. A. , Scheuer Rachel D. , van der Ende Marchina E. , Gruters Rob A. , Luider Theo M.
Published: March 2011

A new and reliable mass spectrometric method using an isotope dilution method in combination with matrix‐assisted laser desorption/ionization‐triple quadrupole tandem mass spectrometry (ID‐MALDI‐QqQ‐MS/MS) has been developed and validated for the determination of concentrations of the antiretroviral drug tenofovir (TNV) in plasma from HIV‐infected adults. The advantage of this new method is that (1) the method is ultrafast and (2) can be applied for high‐throughput measurement of TNV in plasma. The method is based on a simple plasma deproteinization step in combination with the use of [adenine‐13C5]‐TNV as the internal standard. TNV and [adenine‐13C5]‐TNV were monitored by multiple reaction monitoring using the transition m/z 288.0 → 176.2 and m/z 293.2 → 181.2 for TNV and [adenine‐13C5]‐TNV, respectively. The method was validated according to the most recent FDA guidelines for the development and validation of (new) bio‐analytical assays. Validated method parameters were: linearity, accuracy, precision and stability of the method. The lowest limit of quantification was 0.10 µmol/l, whereas the limit of detection determined at a signal‐to‐noise ratio (S/N = 3:1) in pooled drug free human control plasma was 0.04 µmol/l. The validated method was successfully applied and tested for its clinical feasibility by the analysis of plasma samples from selected HIV‐infected adults receiving the prodrug tenofovir disoproxil fumarate. Observed plasma TNV concentrations ranged between 0.11 and 0.76 µmol/l and measured plasma TNV concentrations were within the therapeutically relevant concentration range. Copyright © 2011 John Wiley & Sons, Ltd.
An LC–MS screening method with library identification for the detection of steroidsin dietary supplements
Authors: Becue Ilse , Poucke Christof Van , Peteghem Carlos Van
Published: March 2011

For many years anabolic‐androgenic steroids (AAS) are by far the most frequently detected pharmacological substances in doping control. In order to improve their performances, professional sportsmen are often tempted to take dietary supplements. However, due to the frequent and widespread occurrence of contaminated supplements, the use of such products is not without risk for the athletes involved. In order to minimize the chances of an unattended positive doping test or serious health problems, fast and reliable screening methods for the detection of anabolic steroids in dietary supplements are needed. A general screening procedure requires the fast and unambiguous detection of a large range of steroids. Gas chromatography–mass spectrometry (GC–MS) has been used intensively in the detection of doping substances for the past 40 years. Over time, many laboratories have delivered spectra to be included in standard reference databases, one of which is maintained by the National Institute of Standards and Technology (NIST) (Gaithersburg, MD, USA). In recent years, however, liquid chromatography coupled to mass spectrometry (LC–MS) has gained popularity. Unfortunately, existing GC–MS libraries are not applicable to LC–MS analysis. In the present study, a new mass spectral library of 88 steroids was developed, along with a fast UPLC–MS method. For the construction of this mass spectral library, three different mass spectra were measured for each steroid, with a sample cone voltage of 30, 60 and 100 V, respectively. This method was then successfully tested on contaminated dietary supplements which had previously been tested by means of a targeted LC–MS/MS method. Overall, the library search was shown to identify the same compounds as the MRM method. Copyright © 2011 John Wiley & Sons, Ltd.
Simple and sensitive determination of nitroimidazole residues in honey using stir bar sorptive extraction with mixed mode monolith followed by liquid chromatography
Authors: Huang Xiaojia , Lin Jianbin , Yuan Dongxing
Published: March 2011

In the present study, we developed a simple and sensitive method for the simultaneous determination of metronidazole (MTZ), ronidazole (RNZ), dimetridazole (DMZ), and tinidazole (TNZ) in honey. Honey samples were diluted with water, then directly treated by stir bar sorptive extraction (SBSE) based on poly(methacrylic acid‐3‐sulfopropyl ester potassium salt‐co‐divinylbenzene) monolithic material. The analytes were analyzed by HPLC equipped with diode array detector. In the optimized process, several parameters, including the composition of desorption solvent, pH value and ionic strength in sample matrix, extraction, and desorption time, were investigated in detail. Under the optimized conditions, the detection limits (S/N=3) and quantification limits (S/N=10) of the proposed method for the target compounds were achieved within the range of 0.47–1.52 and 1.54–5.0 μg/kg from spiked honey sample, respectively. The calibration curves showed the linearity ranging from 2 to 200 μg/kg for dimetridazole and tinidazole, 5–200 μg/kg for metronidazole and ronidazole. Method repeatability presented as intra‐ and interday precisions were found with the RSDs <4.43 and 4.41%, respectively. Finally, the developed method was successfully applied to the determination of nitroimidazoles in different honey samples and satisfactory recoveries of spiked target compounds were in the range of 71.1–114%.
Validation of elk resource selection models with spatially independent data
Authors: Coe Priscilla K. , Johnson Bruce K. , Wisdom Michael J. , Cook John G. , Vavra Martin , Nielson Ryan M.
Published: March 2011

Knowledge of how landscape features affect wildlife resource use is essential for informed management. Resource selection functions often are used to make and validate predictions about landscape use; however, resource selection functions are rarely validated with data from landscapes independent of those from which the models were built. This problem has severely limited the application of resource selection functions over larger geographic areas for widely distributed species. North American elk (Cervus elaphus) is an example of a widely‐distributed species of keen interest to managers and for which validation of resource selection functions over large geographic areas is important. We evaluated the performance of resource selection functions developed for elk on one landscape in northeast Oregon with independent data from a different landscape in the same region. We compared predicted versus observed elk resource use for 9 monthly or seasonal periods across 3 yr. Results showed strong, positive agreement between predicted and observed use for 2 spring and 3 late summer‐early fall models (3‐yr r = 0.81–0.95). Predicted versus observed use was negatively or weakly positively correlated for 3 summer models and 1 mid‐fall model (3‐yr r = −0.57–0.14). Predicted and observed use correlated well when forage was limited (spring and late summer or early fall), corresponding to important biological stages for elk (parturition and breeding seasons). For these seasonal periods, model covariates such as rate of motorized traffic and canopy closure often were effective predictors of elk resource selection. The models we validated for spring and late summer‐early fall may be used to evaluate management activities in areas with similar landscape characteristics. © 2010 The Wildlife Society.
Ecological and methodological factors affecting detectability and population estimation in elusive species
Authors: Willson John D. , Winne Christopher T. , Todd Brian D.
Published: March 2011

Although mark‐recapture methods are among the most powerful tools for monitoring wildlife populations, the secretive nature of some species requires a comprehensive understanding of the factors that affect capture probability to maximize accuracy and precision of population parameter estimates (e.g., population size and survivorship). Here, we used aquatic snakes as a case study in applying rigorous mark‐recapture methods to estimate population parameters for secretive species. Specifically, we used intensive field sampling and robust design mark‐recapture analyses in Program MARK to test specific hypotheses about ecological and methodological factors influencing detectability of two species of secretive aquatic snakes, the banded watersnake (Nerodia fasciata), and the black swamp snake (Seminatrix pygaea). We constructed a candidate set of a priori mark‐recapture models incorporating various combinations of time‐ and sex‐varying capture and recapture probabilities, behavioral responses to traps (i.e., trap‐happiness or trap‐shyness), and temporary emigration, and we ranked models for each species using Akaike's Information Criterion. For both banded watersnakes and black swamp snakes we found strong support for time‐varying capture and recapture probabilities and strong trap‐happy responses, factors that can bias population estimation if not accommodated in the models. We also found evidence of sex‐dependent temporary emigration in black swamp snakes. Our study is among the first comprehensive assessments of factors affecting detectability in snakes and provides a framework for studies aimed at monitoring populations of other secretive species. © 2010 The Wildlife Society.
Population estimation and monitoring of an endangered lagomorph
Authors: Schmidt Jason A. , Mccleery Robert A. , Schmidt Paige M. , Silvy Nova J. , Lopez Roel R.
Published: March 2011

We conducted the most intensive estimate of the endangered Lower Keys marsh rabbit (Sylvilagus palustris hefneri) metapopulation to date using pellet surveys and capture–recapture methodology. We livetrapped 83 rabbits, evaluated 5 closed population models, and selected the model that best represented the data. We considered the variation in behavioral response model the best model and correlated (r2 = 0.913) its patch population estimates to patch pellet densities. From the prediction equation, we generated a range‐wide metapopulation estimate of 317 rabbits, a western clade population of 257 rabbits, an eastern clade population of 25 rabbits, and translocated marsh rabbit populations of 35 and zero on Little Pine and Water keys, respectively. A subset of patches whose marsh rabbit subpopulations were last estimated in 1993 exhibited a 46% decline in abundance over 15 yr. Due to the low estimate of the eastern clade population, special effort should be initiated to avoid loss of genetic diversity. The prediction equation suffers from limited data at high pellet densities, patches with ≥5 pellets/m2. Future studies should investigate if the slope of the regression is indeed near 1 by sampling patches across the range of pellet densities, especially those with ≥5 pellets/m2. The equation provides managers a quick, efficient, and noninvasive method to estimate marsh rabbit abundance from pellet counts but the confidence of predicted rabbit densities from high pellet density patches is low. © 2011 The Wildlife Society
Comparing a bioenergetics model with feeding rates of caged European starlings
Authors: Jeffrey Homan H. , Stahl Randal S. , Linz George M.
Published: March 2011

We tested a bioenergetics model integrated within a mortality model that estimates numbers of European starlings (Sturnus vulgaris) poisoned with the avicide, Compound DRC‐1339 Concentrate. The bioenergetics model predicted daily metabolic rate. Accuracy and reliability of this variable is critical because other algorithms (e.g., toxicity regressions, feeding behavior) in the mortality model depend on metabolic rate to calculate the amount of DRC‐1339 ingested per bird. We tested the bioenergetics model by comparing its estimates of metabolic rate with those generated from measuring feeding rates of caged starlings during a feeding trial conducted outdoors during January 2008. Over the 12‐day feeding trial, daily feeding rates of caged starlings indicated that metabolic rates ranged from 157 kJ/bird per day to 305 kJ/bird per day. The bioenergetics model predicted metabolic rates ranging from 208 kJ/bird per day to 274 kJ/bird per day. There was no difference between these 2 independently derived estimates of daily metabolic rate (paired t‐test: t(11) = 1.4, P = 0.18). Using 95% confidence intervals calculated from variation of feeding rates among cages (n = 4, 6 birds/cage), the bioenergetics model's estimates were within 95% confidence intervals on 9 of 12 days and greater than the upper 95% confidence interval on 3 days. Daily estimates of metabolic rate were directly correlated between the bioenergetics model and the feeding‐rate model (r12 = 0.57, P = 0.05). A broad range of temperatures (−17°C to 14°C), wind speeds (0–40 km/hr), and percent cloud cover (0–100%) were encountered during the feeding trial. The bioenergetics model's predictions appeared robust to varying meteorological conditions typical of winters in middle latitudes of the interior United States. Compound DRC‐1339 Concentrate is used by USDA Wildlife Services to manage chronic infestations of starlings at livestock facilities, which occur mainly during fall and winter. Compared to other methods used for estimating DRC‐1339 mortality (e.g., counting birds pre‐ and posttreatment), bioenergetics modeling should improve the mortality model's overall accuracy and precision. © The Wildlife Society, 2011
Survival of white‐tailed deer neonates in Minnesota and South Dakota
Authors: Grovenburg Troy W. , Swanson Christopher C. , Jacques Christopher N. , Klaver Robert W. , Brinkman Todd J. , Burris Benjamin M. , Deperno Christopher S. , Jenks Jonathan A.
Published: March 2011

Understanding the influence of intrinsic (e.g., age, birth mass, and sex) and habitat factors on survival of neonate white‐tailed deer improves understanding of population ecology. During 2002–2004, we captured and radiocollared 78 neonates in eastern South Dakota and southwestern Minnesota, of which 16 died before 1 September. Predation accounted for 80% of mortality; the remaining 20% was attributed to starvation. Canids (coyotes [Canis latrans], domestic dogs) accounted for 100% of predation on neonates. We used known fate analysis in Program MARK to estimate survival rates and investigate the influence of intrinsic and habitat variables on survival. We developed 2 a priori model sets, including intrinsic variables (model set 1) and habitat variables (model set 2; forested cover, wetlands, grasslands, and croplands). For model set 1, model {Sage‐interval} had the lowest AICc (Akaike's information criterion for small sample size) value, indicating that age at mortality (3‐stage age‐interval: 0–2 weeks, 2–8 weeks, and >8 weeks) best explained survival. Model set 2 indicated that habitat variables did not further influence survival in the study area; β‐estimates and 95% confidence intervals for habitat variables in competing models encompassed zero; thus, we excluded these models from consideration. Overall survival rate using model {Sage‐interval} was 0.87 (95% CI = 0.83–0.91); 61% of mortalities occurred at 0–2 weeks of age, 26% at 2–8 weeks of age, and 13% at >8 weeks of age. Our results indicate that variables influencing survival may be area specific. Region‐specific data are needed to determine influences of intrinsic and habitat variables on neonate survival before wildlife managers can determine which habitat management activities influence neonate populations. © 2011 The Wildlife Society
Occupancy modeling of ruffed grouse in the Black Hills National Forest
Authors: Hansen Christopher P. , Millspaugh Joshua J. , Rumble Mark A.
Published: March 2011

Ruffed grouse (Bonasa umbellus) are a popular game bird and the management indicator species for quaking aspen (Populus tremuloides) in the Black Hills National Forest (BHNF), which requires development of a robust monitoring protocol to evaluate trends in ruffed grouse populations. We used roadside drumming surveys in spring 2007 and 2008 to estimate ruffed grouse occupancy and detection probabilities in the BHNF while simultaneously assessing the influence of sampling and site covariates on these processes. Ruffed grouse occupancy estimates were constant between spring 2007 and 2008 (Ψ = 0.12, SE = 0.03) and were positively influenced by the amount of aspen surrounding the site. Detection probability estimates were constant between spring 2007 and 2008 (p = 0.27, SE = 0.06) and were influenced by survey date in a quadratic form and negatively influenced by wind speed and time of the survey. Collectively, our results demonstrated that ruffed grouse occupancy and detection probabilities in the BHNF were low. Occupancy could be increased by increasing the extent of aspen. To improve monitoring efficiency and maximize probability of detecting ruffed grouse, ruffed grouse monitoring should be conducted during the peak of drumming (mid‐May), during favorable weather conditions such as low wind speeds and little precipitation, and during early morning, near sunrise. © 2010 The Wildlife Society.
Evaluating how hunters see and react to telemetry collars on white‐tailed deer
Authors: Jacques Christopher N. , van Deelen Timothy R. , Hall Wayne H. , Martin Karl J. , Vercauteren Kurt C.
Published: March 2011

Fates of individuals outfitted with radiotransmitters commonly are used for estimating survival rates in populations of large animals that are hunted. Despite precautions, this practice may be subject to complex biases associated with hunter reaction to presence of radiotransmitters. To assess this potential bias we conducted an experiment using artificial deer (i.e., decoys) to measure hunters' abilities to see deer and determine if deer seen were wearing radiocollars. We used logistic regression to quantify probabilities that seeing deer and subsequently seeing radiocollars might be influenced by distance, percent visual obstruction, body orientation, hunter experience, and antler characteristics of deer. Additionally, we evaluated how experience and antler characteristics of deer might influence a hunter's decision to harvest a radiocollared deer. We found that 25.8% of the potentially observable collared deer (n = 663) were subsequently observed by hunters. Odds of observing deer and radiocollars increased 95% and 230%, respectively, for each additional log(yr) of hunting experience. Willingness to harvest radiocollared deer increased 89% for each additional log(yr) of hunting experience and 144% for large‐antlered deer relative to antlerless deer. When hunting is an important source of mortality, analysts need to understand how potential biases associated with observing deer are associated with hunters' reactions to and subsequent decisions to harvest radiocollared animals. Our study suggested that presence of radiocollars may influence a deer's potential risk of being harvested and in turn bias telemetry‐based estimates of survival, given that hunting mortality is the largest component of total mortality in hunted deer populations. Collar‐based telemetry is used nearly universally by wildlife managers and researchers throughout North America and elsewhere to estimate and monitor the survival of big game populations that are managed through hunting. Our findings demonstrate that these estimates are likely subject to complex and systematic biases that managers should consider when evaluating future population‐level effects of managed hunting. © 2011 The Wildlife Society
Intercolony variation in growth of black brant goslings on the Yukon‐Kuskokwim Delta, Alaska
Authors: Fondell Thomas F. , Flint Paul L. , Sedinger James S. , Nicolai Christopher A. , Schamber Jason L.
Published: March 2011

Recent declines in black brant (Branta bernicla nigricans) are likely the result of low recruitment. In geese, recruitment is strongly affected by habitat conditions experienced by broods because gosling growth rates are indicative of forage conditions during brood rearing and strongly influence future survival and productivity. In 2006–2008, we studied gosling growth at 3 of the 4 major colonies on the Yukon‐Kuskokwim Delta, Alaska. Estimates of age‐adjusted gosling mass at the 2 southern colonies (approx. 30% of the world population of breeding black brant) was low (gosling mass at 30.5 days ranged 346.7 ± 42.5 g to 627.1 ± 15.9 g) in comparison to a third colony (gosling mass at 30.5 days ranged 640.0 ± 8.3 g to 821.6 ± 13.6 g) and to most previous estimates of age‐adjusted mass of brant goslings. Thus, our results are consistent with the hypothesis that poor gosling growth is negatively influencing the brant population. There are 2 non‐mutually exclusive explanations for the apparent growth rates we observed. First, the population decline may have been caused by density‐independent factors and habitat capacity has declined along with the population as a consequence of the unique foraging feedback between brant and their grazing habitats. Alternatively, a reduction in habitat capacity, as a result of changes to the grazing system, may have negatively influenced gosling growth, which is contributing to the overall long‐term population decline. We found support for both explanations. For colonies over habitat capacity we recommend management to enhance foraging habitat, whereas for colonies below habitat capacity we recommend management to increase nesting productivity. © 2010 The Wildlife Society.
Implications of chronic wasting disease, cougar predation, and reduced recruitment for elk management
Authors: Sargeant Glen A. , Weber Duane C. , Roddy Daniel E.
Published: March 2011

Emerging diseases and expanding carnivore populations may have profound implications for ungulate harvest management and population regulation. To better understand effects of chronic wasting disease (CWD) and cougar (Puma concolor) predation, we studied mortality and recruitment of elk (Cervus elaphus) at Wind Cave National Park (WICA) during 2005–2009. We marked 202 elk (83 subadult M and 119 subadult and ad F) with Global Positioning System (GPS) collars, observed 28 deaths during 74,220 days of monitoring, and investigated 42 additional deaths of unmarked elk found dead. Survival rates were similar for males and females and averaged 0.863 (SE = 0.025) annually. Leading causes of mortality included hunting (0.065, SE = 0.019), CWD (0.034, SE = 0.012), and cougar predation (0.029, SE = 0.012). Marked elk killed by hunters and cougars typically were in good physical condition and not infected with CWD. Effects of mortality on population growth were exacerbated by low rates of pregnancy (subadults = 9.5%, SE = 6.6%; ad = 76.9%, SE = 4.2%) and perinatal survival (0.49, SE = 0.085 from 1 Feb to 1 Sep). Chronic wasting disease, increased predation, and reduced recruitment reduced the rate of increase for elk at WICA to approximately λ = 1.00 (SE = 0.027) during the past decade. Lower rates of increase are mitigating effects of elk on park vegetation, other wildlife, and neighboring lands and will facilitate population control, but may reduce opportunities for elk hunting outside the park. © 2011 The Wildlife Society
Migration patterns of pronghorn in southwestern North Dakota
Authors: Kolar Jesse L. , Millspaugh Joshua J. , Stillings Bruce A.
Published: March 2011

Wildlife managers need empirical data about pronghorn (Antilocapra americana) movements in North Dakota to assess whether mid‐summer surveys represent occupancy of pronghorn in hunting units during the fall hunting season. Using data from 121 radiocollared pronghorn we evaluated patterns of pronghorn migrations in southwestern North Dakota from 2004 to 2007. Pronghorn exhibited 2 primary movement patterns between summer and winter ranges: migrations >15 km (45%) and movement <15 km (55%). Most migratory pronghorn moved northeast or east in the spring and southwest or west in the fall. Average distance moved for migratory pronghorn was 70.6 km (range = 17.4–253 km). Mean date of pronghorn migration in spring was 20 March (SD = 20 days) and in fall was 22 October (SD = 17 days). Nearly all migratory pronghorn (97%) returned to within 15 km of their previous summer range, whereas only 61% of pronghorn returned to within 15 km of their previous winter range. Most pronghorn moved across hunting and survey unit boundaries; however, only 7 fall migrations occurred between the aerial survey and the hunting season. During years of our study, the mid‐summer survey provided representative information about hunting unit occupancy of radiocollared pronghorn for the fall hunting season. © 2011 The Wildlife Society
Simulating northern bobwhite population responses to nest predation, nesting habitat, and weather in south Texas
Authors: Rader Michael J. , Brennan Leonard A. , Brazil Kyle A. , Hernández Fidel , Silvy Nova J.
Published: March 2011

Nest predation is thought to be one of the major factors limiting northern bobwhite (Colinus virginianus) populations. We examined the relative impact of altering nest‐predation rate, nesting habitat, and weather (i.e., temp and precipitation) on northern bobwhite population dynamics in a hypothetical 15,000‐ha subtropical‐rangeland ecosystem in south Texas using a simulation model. The systems model consisted of a 3‐stage (i.e., eggs, juv, and ad) bobwhite population with dynamics influenced by variables affecting production, recruitment, nest predation, and mortality. We based model parameters on data collected from a 3‐yr nest‐predator study employing infrared‐camera technology, from ongoing field research using a radio‐marked population of wild bobwhites, and from the literature. The baseline simulated bobwhite population dynamics corresponded closely to empirical data, with no difference between medians of simulated (n = 30 yr) and observed bobwhite age ratios over a 28‐yr period. Similarly, a time‐series comparison of simulated and observed age ratios showed most (89%) observed values fell within the 5th and 95th percentiles of the simulated data over the 28‐yr period. We created simulated population scenarios representing 1) baseline historical conditions, 2) predator control, 3) low precipitation, 4) low precipitation with predator control, 5) high temperature, 6) high temperature with predator control, 7) reduced nest‐clump availability, and 8) reduced nest‐clump availability with predator control that resulted in considerably different median bobwhite densities over 10 yr. For example, under simulated predator control, populations increased by about 55% from the baseline scenario, whereas under simulated reduced nest‐clump availability, populations decreased by about 75% from the baseline scenario. Comparisons of time‐series for each scenario showed that reduced nest‐clump availability, low precipitation, and high temperature reduced bobwhite densities to a larger degree compared to a natural nest predation rate. Reduced nest‐clump availability resulted in the most substantial decline of simulated bobwhite densities. Simulations suggested that management efforts should focus on maintaining adequate nest‐clump availability and then possibly consider nest predator control as a secondary priority. © 2010 The Wildlife Society
Stopover habitats of spring migrating surf scoters in southeast Alaska
Authors: Lok Erika K. , Esler Daniel , Takekawa John Y. , de la Cruz Susan W. , Sean Boyd W. , Nysewander David R. , Evenson Joseph R. , Ward David H.
Published: March 2011

Habitat conditions and nutrient reserve levels during spring migration have been suggested as important factors affecting population declines in waterfowl, emphasizing the need to identify key sites used during spring and understand habitat features and resource availability at stopover sites. We used satellite telemetry to identify stopover sites used by surf scoters migrating through southeast Alaska during spring. We then contrasted habitat features of these sites to those of random sites to determine habitat attributes corresponding to use by migrating scoters. We identified 14 stopover sites based on use by satellite tagged surf scoters from several wintering sites. We identified Lynn Canal as a particularly important stopover site for surf scoters originating throughout the Pacific winter range; approximately half of tagged coastally migrating surf scoters used this site, many for extended periods. Stopover sites were farther from the mainland coast and closer to herring spawn sites than random sites, whereas physical shoreline habitat attributes were generally poor predictors of site use. The geography and resource availability within southeast Alaska provides unique and potentially critical stopover habitat for spring migrating surf scoters. Our work identifies specific sites and habitat resources that deserve conservation and management consideration. Aggregations of birds are vulnerable to human activity impacts such as contaminant spills and resource management decisions. This information is of value to agencies and organizations responsible for emergency response planning, herring fisheries management, and bird and ecosystem conservation. © 2010 The Wildlife Society
Hibernacula selection by Townsend's big‐Eared bat in southwestern Colorado
Authors: Hayes Mark A. , Schorr Robert A. , Navo Kirk W.
Published: March 2011

In western United States, both mine reclamations and renewed mining at previously abandoned mines have increased substantially in the last decade. This increased activity may adversely impact bats that use these mines for roosting. Townsend's big‐eared bat (Corynorhinus townsendii) is a species of conservation concern that may be impacted by ongoing mine reclamation and renewed mineral extraction. To help inform wildlife management decisions related to bat use of abandoned mine sites, we used logistic regression, Akaike's information criterion, and multi‐model inference to investigate hibernacula use by Townsend's big‐eared bats using 9 years of data from surveys inside abandoned mines in southwestern Colorado. Townsend's big‐eared bats were found in 38 of 133 mines surveyed (29%), and occupied mines averaged 2.6 individuals per mine. The model explaining the most variability in our data included number of openings and portal temperature at abandoned mines. In southwestern Colorado, we found that abandoned mine sites with more than one opening and portal temperatures near 0°C were more likely to contain hibernating Townsend's big‐eared bats. However, mines with only one opening and portal temperatures of ≥10°C were occasionally occupied by Townsend's big‐eared bat. Understanding mine use by Townsend's big‐eared bat can help guide decisions regarding allocation of resources and placement of bat‐compatible closures at mine sites scheduled for reclamation. When feasible we believe that surveys should be conducted inside all abandoned mines in a reclamation project at least once during winter prior to making closure and reclamation recommendations. © 2010 The Wildlife Society.
The effect of anthropogenic resources on the space‐use patterns of golden jackals
Authors: Rotem Guy , Berger Haim , King Roni , (Kutiel) Pua Bar , Saltz David
Published: March 2011

We studied the influence of agricultural villages on space‐use patterns of golden jackals (Canis aureus Linnaeus) in the Mediterranean region of Israel. Villages in our research area attract jackals due to poor sanitation conditions in and around villages. As resources in these villages are abundant and predictable, we expected that space‐use patterns of jackals near those villages, including home‐range characteristics and movement paths, would differ from those of jackals inhabiting more natural areas. Using radio‐locations from 16 individuals (8 near villages and 8 from more natural areas), we found that mean home‐range size of jackals close to villages was 6.6 ± 4.5 km2, smaller than mean home‐range size of jackals in more natural areas (21.2 ± 9.3 km2, P = 0.001). Similarly, core area size of jackals near villages was 1.2 ± 0.92 km2, compared to 3.5 ± 1.6 km2 for individuals inhabiting more natural areas (P = 0.004). The core area/home‐range ratio was greater for jackals near villages than for those occupying more natural areas (0.122 ± 0.045 vs. 0.095 ± 0.037, respectively, P = 0.004). Jackals moved little during the day, with day ranges smaller for jackals near villages than away from them (1.65 ± 0.67 vs. 7.5 ± 5.6 km2, respectively, P = 0.028). However, jackals near villages moved as much at night as did jackals in more natural areas, although movement was in a less directional manner. Changes in distribution and predictability of resources due to anthropogenic activity affect not only the home‐range size of jackals, but also how they utilize and move through space. © 2011 The Wildlife Society.
Pyrometer optimiert selektives Weichlöten mit dem Laser
Authors: Reinl Steffen , Hoppert Bernd
Published: March 2011

Selektives Löten elektronischer Komponenten ist ein weit verbreitetes Verfahren in der Produktion elektronischer Baugruppen. Doch zunehmend miniaturisierte Bauteile und Baugruppen lassen konventionelle selektive Lötverfahren an ihre Grenzen stoßen. Für diesen Anwendungsbereich hat der Diodenlaser neue Möglichkeiten eröffnet, insbesondere dann, wenn eine eigene Prozesskontrolle das berührungslose Lötverfahren steuert und überwacht.
Kleiner Laser, große Wirkung
Authors: Frede Maik , Moalem Anas
Published: March 2011

Das Laserschweißen von Kupfer reduzierte sich aufgrund der hohen Prozessunsicherheit bisher auf nicht automatisierte, manuelle Applikationen und Anwendungen. Mit Hilfe eines neu entwickelten Laser‐Vorpulsmoduls konnte nun in Verbindung mit einem etablierten IR‐Lasersystem eine 100‐prozentige Prozesssicherheit beim Kupferschweißen demonstriert werden. Die zusätzlich eingebrachte Energie des Vorpulses ist dabei um einen Faktor 1000 kleiner als die Energie des eigentlichen Schweißpulses, ermöglicht jedoch definierte Prozessbedingungen. Das neue Verfahren führt weiterhin zu einer signifikanten Verbesserung der Energieeffizienz und des Schweißbilds.
Laserschweißen von Mischverbindungen
Authors: Standfuß Jens , Rath Wolfram , Valentin Martin , Falldorf Heiko
Published: March 2011

Getrieben von der allgemeinen Forderung, Bauteile möglichst effizient eigenschafts‐ und gewichtsoptimiert herzustellen, sind stoffschlüssig gefügte Mischverbindungen in vielen Anwendungsbereichen gefordert. Das Schweißen von Kombinationen aus verschiedenen Werkstoffen ermöglicht, die spezifischen Eigenschaften der Stoffe optimal zu nutzen. Dies gestaltet sich jedoch in vielen Fällen schwierig, da die Komponenten sich deutlich in ihren thermophysikalischen und stofflichen Eigenschaften unterscheiden.
Arraytechnologie statt einzelner Laserdiode
Authors: Beier Bernard
Published: March 2011

Nicht nur in der Druckbranche muss es schnell gehen. Ein kompakter Laserkopf mit einer Vielzahl an Laserstrahlen weckt deshalb branchenübergreifendes Interesse. Überall dort, wo es gilt Strukturen auf große Flächen in kurzer Zeit aufzubringen, kann er zum Einsatz kommen.
Mikrostrukturieren mit Zukunft
Authors: Holtkamp Jens , Hartmann Claudia , Gillner Arnold , Beckemper Stefan , Dohrn Andreas , Eifel Stephan
Published: March 2011

Zum mikrometerfeinen Strukturieren funktioneller Oberflächen eigenen sich Kurzpuls‐ und Ultrakurzpulslaser inzwischen ebenso gut wie die klassischen Fertigungstechnologien. Das belegt auch die Vielzahl der Anwendungen, bei denen Laser derzeit die Oberflächen strukturieren. Speziell zum wirtschaftlichen Strukturieren von größeren Flächen bedarf es aber weiterer Forschungsaktivitäten. Sie öffnen den (Ultra‐) Kurzpulslasern zusätzliches Einsatzpotenzial.
Vereinfachtes Sicherheitskonzept bei voller Flexibilität
Authors: Leibold Kai
Published: March 2011

Stillstand heißt Rückschritt. Aus diesem Grund sind die kontinuierliche Weiterentwicklung bestehender Anlagenkonzepte und innovative Neuentwicklungen von entscheidender Bedeutung. Mit dem Konzept ROBLAS („Roboter‐Laser‐Schneiden”︁) wurde eine Technologie entwickelt, die die Kernziele: „höchste Flexibilität eines Industrieroboters mit einem stark vereinfachten Sicherheitskonzept”︁ für die Laserbearbeitung verwirklicht.
First, lead yourself
Authors: Daft Richard L.
Published: March 2011

“Leaders usually know the correct way to lead others, so why don't they do it?” Richard L. Daft asks. Too often, Daft says, leaders focus on getting the best out of other people, without the necessary preparation, because “the first job of leadership is often getting the best out of yourself.” Personal mastery is essential, yet difficult to achieve. Why do we find it so difficult to lead ourselves and what steps can we take to achieve this difficult task? Daft offers new and insightful answers to these questions.
A Simple Access to the (Log/Normal) Molecular Weight Distribution Parameters of Polymers Using PGSTE NMR
Authors: Gong Xiaoliang , Hansen Eddy W. , Chen Qun
Published: March 2011

A log/normal MWD is characterized by two parameters, its mean molecular weight M0 and width σ. It is demonstrated how these parameters can be obtained by model fitting a stretched exponential function (SEF), as characterized by two parameters β and DS, to the PGSTE response curve. Based on simulations, two general empirical equations relating β and DS to M0 and σ are found. The model enables the MWD characteristics to be determined if the scaling law between diffusivity and molecular weight is known. The sensitivity and relative error of σ and M0 are discussed and the applicability of the model is illustrated by analyzing experimental NMR response curve of some PEO samples. The key advantages of this technique are its simplicity, numerical robustness, and reliability.

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Fabrication of Sealed µ‐Channels Through a Fast and Reliable Photopolymerization Process
Authors: Suriano Raffaella , Levi Marinella , Emilitri Elisa , Momo Chiara , Turri Stefano
Published: March 2011

Sealed microchannels and simple microfluidic networks with good efficiency and controlled quality of the structures were developed from a photocurable and PCR‐compatible material based on a PEG–methacrylate oligomers mixture. The influence of UV exposure time and of conversion degree on microchannel geometry were studied to obtain structures with controlled depth, vertical sidewalls, and good reproducibility. The roughness inside channels was as low as 50–100 nm, less than that typical of alternative LOC prototyping techniques such as micromilling. Efficient channel sealing was also achieved without using a different sealing material. Surface smoothness and hydrophilicity (static contact angle below 60°) allow spontaneous water flow inside the channels by capillarity without need of surface treatments.

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Experimental techniques in free radical polymerization kinetics
Authors: Stickler Manfred
Published: March 2011

A detailed review is given on experimental techniques in free‐radical polymerization kinetics. Besides the wellknown and familiar methods for the determination of monomer conversion (rate of polymerization) and initiator decomposition (rate of initiation) some further possibilities of getting more detailed information about the reaction system are shortly discussed (e.g. detection of end‐groups in the polymer, determination of molecular weight distributions).

Special emphasis is given to some newer techniques with their abilities of automatic acquisition and treatment of data with the help of microprocessors.

Problems associated with calibration procedures as well as error sources are discussed. Techniques for both steady state and non‐stationary polymerization experiments are reported.
Reactivities of acrylic monomers and their radicals in radical polymerization
Authors: Otsu Takayuki
Published: March 2011

The reactivities of acrylic derivatives in radical polymerization were largely dependent on polar, resonance and steric effects of their substituents. Although the change in ester alkyl substituents resulted in only polar effects, the introduction of the substituent into α‐position increased both resonance and steric effects, and that into β‐position increased steric effect greatly. The steric effects of o− and N–alkyl substituents in phenyl methacrylates and methacrylamides, respectively, were also important, i.e. 2,6‐di‐t‐butylphenyl methacrylate and N,N‐dialkylmeth‐acrylamides did not homopolymerize, although the respective acrylates and acrylamides could easily polymerize. It was noted that the steric effect by three alkyl groups bonded at α‐and o− or N‐positions played an important role. However, fumaric esters, β‐alkoxycarbonyl–acrylic esters, having bulky ester substituents were found to be readily polymerized to give high‐molecular‐weight and less‐ or non‐flexible polymers. In these polymerizations, the bimolecular termination is hindered, i.e. the life‐time of the propagating radical becomes longer. The propagating radicals were easily detectable from the polymerization mixtures by direct ESR measurement. Some features of these radical polymerizations are also discussed.
Chemistry and kinetics of the chain transfer reaction
Authors: Farina Mario
Published: March 2011

Chain transfer may be defined as a process in which the growing chain loses its capacity for further growth and the transfer agent (initiator, monomer, polymer, solvent or an extraneous compound) becomes capable of starting a new chain. This reaction has been subjected to extensive studies both for its relevance in interpreting the polymerization mechanism and for its practical importance as a method for controlling the molecular mass. In this communication the chemistry of the process is first described, then the classical kinetic approach based on the Mayo equation. Finally a selected number of recent results is discussed: the production of oligomers, the role of chain transfer in copolymerization, formation of branched polymers, catalyzed transfer and use of polyfunctional transfer agents.
Synthesis of telechelics and telomers by radical polymerization
Authors: Heitz W.
Published: March 2011

Summary

Telechelics are α, Q‐bifunctional oligomers or low molecular weight polymers. They find use to obtain block copolymers in polycondensation and polyaddition reactions. Telechelics can be synthesized in an initiator controlled polymerization or in a telomerization.

In the initiator controlled preparation of telechelics by radical polymerization the efficiency of the initiator can be higher than 0.9 if the polymerization is effected in bulk or at high concentrations. The initiators suitable to introduce functional end groups are discussed. Only those monomers can be used which terminate by combination. This is not a limitation in telomerization. Transfer agents resulting in polymers with two functional end groups are discussed.
Initiation, propagation and termination in free radical copolymerization
Authors: Russo Saverio
Published: March 2011

At present, the full sequence of events in free‐radical copolymerization cannot be described by a simple kinetic scheme. Indeed, several attempts to derive the copolymerization rate in homogeneous media on the basis of the usual assumptions considered valid for the polymerization of a single monomer have completely failed in terms of general validity. An overview of the various models, from the classical one based on the chemical control of the bimolecular termination reaction to the more modern approaches which include diffusion control of the termination stage, is presented and critically examined. The complex kinetic behavior which has already been evidenced in previous chapters for the polymerization of many monomer systems is re‐examined in terms of its relevance in the kinetics of the copolymerizing pair. The effect of the reaction medium separately on initiation, propagation, and termination is analyzed and new perspectives for experimental as well as theoretical studies are examined.
Studies of the dispersion polymerisation of methyl methacrylate in nonaqueous media
Authors: Winnik M A , Lukas R. , Chen W. F. , Furlong P.
Published: March 2011

The dispersion polymerisation process has been known for many years but has received comparatively little attention relative to conventional emulsion polymerisation. The dispersion polymerisation technique can be considered as a modified precipitation polymerisation that is carried out in the presence of an amphipathic polymeric stabiliser. This polymeric surfactant imparts colloidal stability to the precipitate that is formed during the reaction, thus allowing further growth into well‐defined, sterically stabilised latex particles. In this paper we discuss the effect that experimental variables such as stabiliser concentration, solvency of the disperson medium, initiator concentration and temperature have on the size of the particles that are formed. This is followed by a review of the polymerisation kinetics. It is concluded that when the dispersion medium is a non‐solvent for the polymer being formed then the locus of polymerisation is largely within the growing paticle and the system follows bulk polymerisation kinetics. The particles that are formed are usually submicron in size. As the solvency of the dispersion medium for the growing polymer particles is increased, then polymerisation of polymer in solution also occurs. The polymeric radicals that are formed in solution are then captured by growing particles. Consequently the locus of the particle polymerisation process changes and there is a concomitant change in the kinetics of polymerisation. Particles of up to 15 μm diameter have been formed in such systems. The reasons for these large variations in particle size are discussed in terms of the coalescence of primary particles that takes place during the polymerisation reaction.