Biomechanical model for the determination of the forces acting on the finger pulley system

A mathematical model proposed by Hume et al., 1991. Journal of Hand Surgery-American Volume 16, 722-730 for the determination of the forces acting on the A2 and A4 pulley was used. The parameters necessary for this determination include the angle of flexion, the positioning of the pulley with respect to the centre of rotation in the proximal interphalangeal joint (PIP), the relative mismatch between bone and tendon width at the location of the respective pulleys as well as the tendon height at this position. This model was further developed to include the stiffness of the respective pulley, as well as the fact, that there are two flexor tendons of which only one passes through both pulleys. Each parameter was then evaluated using a sensitivity analysis proposed by Fasham et al., 1990. Journal of Marine Research 48, 591-639 in order to determine their relative importance for the outcome of the model. The most important parameter proofed to be the positioning of the pulley with respect to the centre of rotation in the PIP joint. This observation enabled us to give the best possible placement for a pulley graft after pulley rupture.     

Bottlenecks to water transport in Quercus robur L.: the abscission zone and its physiological consequences

Cladoptosis, the abscission of twigs, is the main mechanism of changes in crown structure in senescing pedunculate oak (Quercus robur L.). We tested the hypotheses that abscission zones in nodes of old pedunculate oak trees reduce leaf-specific hydraulic conductance of shoots and thereby limit the stomatal conductance and assimilation.Hydraulic conductance and leaf-specific hydraulic conductance, measured with a high pressure flowmeter in 0.5–1.5 m long shoots, were significantly lower in shoots of low vigour compared to vigorous growing shoots in a 165-years-old stand in the southeast of Germany. Two types of bottlenecks to water transport could be identified in shoots of old oak trees, namely nodes and abscission zones. In young twigs, vessel diameter and vessel density in nodes with abscission zones were significantly reduced compared with internodes. In nodes without abscission zones, vessel density was significantly reduced. The reduction of hydraulic conductance was especially severe in the smallest and youngest shoots with diameters less than 2 mm. Internodes of 1–5 mm sapwood diameter had an average hydraulic conductance of 7.13×10⁻⁶±0.2×10⁻⁶ kg s⁻¹ m⁻¹ MPa⁻¹, compared to 4.54×10⁻⁶±0.3×10⁻⁶ kg s⁻¹ m⁻¹ MPa⁻¹ in those with nodes.Maximum stomatal conductance and maximum net assimilation rate increased significantly with hydraulic conductance and leaf-specific hydraulic conductance. Maximum rate of net photosynthesis A_max of the most vigorous shoots (VC0) (7.34±0.55 μmol m⁻² s⁻¹) was significantly higher (P<0.001) than in shoots of other vigour classes (5.97±0.28 μmol m⁻² s⁻¹). Our data support the hypothesis that the changes in shoot and consequently crown architecture that are observed in ageing and declining trees can limit photosynthesis by reducing shoot hydraulic conductance. Abscission zones increase the hydraulic disadvantage of less vigorous compared to vigorously growing twigs. Cladoptosis might serve as a mechanism of selection between twigs of different efficiency.     

Interactive cytogenetic effects on rat bone-marrow due to chronic ingestion of 2,5,2',5' and 3,4,3',4' PCBs.

Rats who were fed low doses of single PCBs, either 2,5,2',5' or 3,4,3',4', did not demonstrate any chromosome breakage or mitotic changes in their bone marrow cells. However, there was a significant increase in chromosome damage observed in bone marrow cells of rats ingesting 10 ppm 2,5,2',5' plus 0.1 ppm 3,3,3',4' in combination. It is suggested that this PCB combination, previously found to cause superadditive chromosome damage in vitro, is also capable of causing chromosome damage in vivo, but these effects do not compromise cell proliferation because the mitotic index is not depressed.     

Temporal transferability of wildlife habitat models: implications for habitat monitoring

Aim Temporal transferability is an important issue when habitat models are used beyond the time frame corresponding to model development, but has not received enough attention, particularly in the context of habitat monitoring. While the combination of remote sensing technology and habitat modelling provides a useful tool for habitat monitoring, the effect of incorporating remotely sensed data on model transferability is unclear. Therefore, our objectives were to assess how different satellite‐derived variables affect temporal transferability of habitat models and their usefulness for habitat monitoring. Location Wolong Nature Reserve, Sichuan Province, China. Methods We modelled giant panda habitat with the maximum entropy algorithm using panda presence data collected in two time periods and four different sets of predictor variables representing land surface phenology. Each predictor variable set contained either a time series of smoothed wide dynamic range vegetation index (WDRVI) or 11 phenology metrics, both derived from single‐year or multi‐year (i.e. 3‐year) remotely sensed imagery acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS). We evaluated the ability of models obtained with these four variable sets to predict giant panda habitat within and across time periods by using threshold‐independent and threshold‐dependent evaluation methods and five indices of temporal transferability. Results Our results showed that models developed with the four variable sets were all useful for characterizing and monitoring giant panda habitat. However, the models developed using multi‐year data exhibited significantly higher temporal transferability than those developed using single‐year data. In addition, models developed with phenology metrics, especially when using multi‐year data, exhibited significantly higher temporal transferability than those developed with the time series. Main conclusions The integration of land surface phenology, captured by high temporal resolution remotely sensed imagery, with habitat modelling constitutes a suitable tool for characterizing wildlife habitat and monitoring its temporal dynamics. Using multi‐year phenology metrics reduces model complexity, multicollinearity among predictor variables and variability caused by inter‐annual climatic fluctuations, thereby increasing the temporal transferability of models. This study provides useful guidance for habitat monitoring through the integration of remote sensing technology and habitat modelling, which may be useful for the conservation of the giant panda and many other species.     

Variation in elk response to roads by season,sex, and road type

Despite the near universal recognition that roads negatively affect wildlife, the mechanisms that elicit animal responses to roads are often ambiguous or poorly understood. We conducted a multi-year, multi-season study to assess the relative influence of roads on elk (Cervus elaphus) in a human-dominated landscape in South Dakota. We evaluated the effects of habitat covariates including security cover, forage quality, distance to roads (primary, secondary, and tertiary), and visibility from roads at the home range scale. We radio-collared 28 elk (21 adult females and 7 adult males) and calculated seasonal (winter, spring, summer, and autumn) utilization distributions (UDs). We assigned habitat covariates to use percentiles within the UDs (1% increments; from 1 to 98 percentiles) and used spatially explicit mixed linear regression to model the relationship between use percentile and habitat covariates. For each season and sex, we evaluated 15 candidate models and used Akaike's Information Criterion weights (ω_i) to identify top-ranking models. We plotted influential coefficients from these models with 95% confidence intervals to examine the magnitude of effects. Our analysis revealed fundamental differences in response to roads, by road type, between sexes, and across seasons. Male elk established home ranges near roads devoid of vehicle traffic in winter, spring, and autumn. In summer, coinciding with peak vehicle traffic levels, male elk reduced their use of habitat that was both visible from and close to primary roads. Female elk subherds similarly responded to primary roads in spring and autumn, during times of year when they were calving and mating, respectively. In spring and summer, female elk subherds selected habitat near roads that were closed to vehicle traffic. Forage quality and security cover were influential in the periphery (>50th use percentile) of elk home ranges, whereas road covariates were more influential towards the core of elk home ranges. This analysis further demonstrates the utility of visibility from road metrics and suggests that the retention of vegetation structures that screen visibility potential from roads could be important components of elk management strategies. © 2012 The Wildlife Society.     

The role of reactivity in DNA templated native chemical PNA ligation during PCR

DNA templated fluorogenic reactions have been used as a diagnostic tool for the sequence specific detection of nucleic acids; and it has been shown that the native chemical ligation between thioester- and 1,2-aminothiol-modified PNA probes is amongst the most selective DNA detection methods reported. We explored whether a DNA templated reaction can be interfaced with the polymerase chain reaction (PCR). This endeavor posed a significant challenge. The reactive groups involved must be sufficiently stable to tolerate the high temperature applied in the PCR process. Nevertheless, the ligation reaction must proceed very rapidly and sequence specifically within the short time available in the annealing and primer extension steps before denaturation is used after approx. 1 min to commence the next PCR cycle. This required a careful optimization of the ternary complex architecture as well as adjustments of probe length and probe reactivities. Our results point to the prime importance of the ligation architecture. We show that once suitable annealing sites have been identified less reactive probe sets may be preferable if sequence specificity is of major concern. The reactivity tuning enabled the development of an in-PCR ligation, which was used for the single nucleotide specific typing of the V600E (T1799A) point mutation in the human BRaf gene. Showcasing the efficiency and sequence specificity of native chemical PNA ligation, attomolar template proofed sufficient to trigger signal while a 1000-fold higher load of single mismatched template failed to induce appreciable signal.     

Using multiple methods to assess detection probabilities of forest-floor wildlife

Many previous comparisons of multiple sampling methods have assumed that detection probabilities for each method are either constant or equal to one. We used 4 sampling methods to estimate detection probabilities for forest-floor dwelling amphibians, reptiles, and small mammals. We investigated associations between seasonality and precipitation on species detection and explored sample design tradeoffs for future studies. Although we captured 25 species, we could reliably detect (detection probability >0.15) only northern short-tailed shrews (Blarina brevicauda) and pygmy and masked shrews (Sorex spp.) using drift fences and red-backed salamanders (Plethodon cinereus) using visual encounter surveys (VES). The use of multiple sampling methods improved detection probabilities for only red-backed salamanders ( = 0.32, 95% CI: 0.24–0.38, = 0.38, 95% CI: 0.32−0.44). Parameter estimates indicated detection of both shrew species was positively related to increased precipitation. Detection probabilities for pygmy and masked shrews and red-backed salamanders were positively and negatively associated with date, respectively. Our power analysis revealed that sampling during rain events increased the power of detecting a change in sorid occupancy by ≥40% (α = 0.05). Our results demonstrate the need to incorporate species detectability when comparing the effectiveness of different trapping methodologies. Furthermore, our study highlights the utility of power analyses for exploring study design tradeoffs for research and monitoring programs. © 2011 The Wildlife Society.     

Behavioral states in space and time: understanding landscape use by an invasive mammal

Animal movement models can be used to understand species behavior and assist with implementation of management activities. We explored behavioral states of an invasive wild pig (Sus scrofa) population that recently colonized central Michigan, USA, 2014–2018. To quantify environmental factors related to wild pig movement ecology and spatio-temporal landscape use, we predicted wild pig behavioral states relative to land cover type, landscape structure (i.e., edge and patch cohesion), and weather conditions. We used global positioning system (GPS)-collars and monitored 8 wild pigs from 2014–2018. We fit local convex hulls and calculated movement metrics revealing 3 wild pig behavioral states (resting, exploratory, and relocating) and constructed a 3-level model to predict behavioral state probabilities relative to biotic and abiotic conditions. Probabilities of exploratory and resting behaviors were higher nearer to riparian and open herbaceous cover types (oftentimes emergent marsh), indicating that these cover types provided security cover during activity and bedding. Hard mast cover types had a strong positive association with relocating behaviors. More cohesive patches of agriculture and shrub cover types were associated with higher probabilities of exploratory behaviors, while resting was more likely in continuous patches of agriculture (mostly mid-summer corn). The probability of exploratory behaviors increased exponentially with warming ambient temperature. Our results may be used by managers to develop control strategies conducive to landscape and environmental conditions where the likelihood of encountering wild pigs is highest or targeting wild pigs when in a behavioral state most vulnerable to a particular removal technique.