Predictive Validity of Critical Power and Functional Threshold Power for Mountain Bike Race Performance.

Miller, M., Witmer, C., Moir, G., Davis, S., East Stroudsburg University, East Stroudsburg, PA Purpose: This study tested the predictive validity of critical power (CP) and functional threshold power (FTP) for mountain bike cross-country (MTB) race performance. Methods: Five well-trained MTB athletes (mean ± s: age: 31.4 ± 9.3 years; mass: 70.8 ± 9.5kg; VO2max: 63.8 ± 7.0 ml/kg/min) volunteered for this study. Participants’ FTP was measured during a ramped cycle ergometer test to exhaustion and was indicated as the point at which blood lactate reached 4.0 mmol/L. This test also served to measure the gas exchange threshold and VO2peak for CPtesting. CP was tested during a 3-minute all-out test on a cycle ergometer against a fixed resistance. MTB performance measures were gathered from a USA Cycling sanctioned MTB race and reduced to mean lap time over four laps of 7.5 km each. Linear regression was used to assess the prediction of MTB performance using either FTP or CP. Results: This study shows that CP can predict MTB better than FTP (R2=0.943 versus R2=0.784). CP can also predict MTB with less error than FTP (39.413 s versus 76.526 s). Conclusion: Coaches and athletes can use this information to gauge ability and prescribe training for MTB athletes

Effects of Precooling on Recreationally Active Individuals During Loaded Carriage Foot Marches in Heated Conditions

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VE-based training strategies for acquiring survey knowledge

Virtual environments (VEs) have been used successfully to train wayfinders to navigate through buildings and learn their layout. However, at the same time, for many, the VE deficiencies have reduced the effectiveness of VEs for training spatial tasks. In an effort to improve VE effectiveness, we conducted research to determine if certain unique capabilities of VEs could compensate for its deficiencies. Research participants were required to learn the layout or configuration of one floor of an office building as portrayed in a VE. To improve spatial learning, we developed three VE navigation training aids: local and global orientation cues, aerial views, and a themed environment enhanced with sights and sounds and divided into four distinct sectors. The navigation aids were provided during the training but were not available during testing of survey knowledge. Of the three training aids investigated, only the aerial views were effective in improving performance on the survey knowledge tests. The effectiveness of the navigation aids seemed to depend on how they were used during training. A retention test given one week after training indicated that spatial knowledge acquired in a VE diminished little over the one-week retention interval

VE-based training strategies for acquiring survey knowledge

Virtual environments (VEs) have been used successfully to train wayfinders to navigate through buildings and learn their layout. However, at the same time, for many, the VE deficiencies have reduced the effectiveness of VEs for training spatial tasks. In an effort to improve VE effectiveness, we conducted research to determine if certain unique capabilities of VEs could compensate for its deficiencies. Research participants were required to learn the layout or configuration of one floor of an office building as portrayed in a VE. To improve spatial learning, we developed three VE navigation training aids: local and global orientation cues, aerial views, and a themed environment enhanced with sights and sounds and divided into four distinct sectors. The navigation aids were provided during the training but were not available during testing of survey knowledge. Of the three training aids investigated, only the aerial views were effective in improving performance on the survey knowledge tests. The effectiveness of the navigation aids seemed to depend on how they were used during training. A retention test given one week after training indicated that spatial knowledge acquired in a VE diminished little over the one-week retention interval

Effects of a Self-Selected Pace on VO2max during a Running Test to Volitional Exhaustion

Please view abstract in the attached PDF file

Aluminum action on mouse bone cell metabolism and response to PTH and 1,25(OH)2D3

Aluminum action on mouse bone cell metabolism and response to PTH and 1,25(OH)2D3. Aluminum (Al) accumulation in bone is associated with low bone formation and mineralization rates; resorption may also be reduced. The mechanism of these Al-induced changes was investigated using cultured mouse osteoblast–like (OB) and osteoclast–like (OC) cells. The Al effect on bone resorption was measured by the in vitro release of 45Ca and β-glucuronidase from mouse fetal limb–bones. Al had a biphasic effect. High concentrations (>1.5 × 10-6 M) of Al inhibited collagen and DNA synthesis, ornithine decarboxylase and alkaline phosphatase activity in OB, and depressed tartrate-resistant acid phosphatase activity in OC. Lower Al concentrations stimulated these cellular activities and 45Ca and β-glucuronidase release from fetal bones. Al had no effect on basal cAMP levels in OB but inhibited the stimulating effect of bPTH on cAMP content. Al also altered the 1,25(OH)2D3 effects on the ornithine decarboxylase activity of OB cells. These data suggest that: (i) the low bone formation observed in vivo during Al intoxication may be due to the inhibition of collagen synthesis and to depressed cell proliferation; and (ii) Al may indirectly influence bone remodeling by interfering with the actions of bPTH and 1,25(OH)2D3 on bone cells

Distribution and turnover of Langerhans cells during delayed immune responses in human skin

The changes in distribution and turnover of T6+ Langerhans cells (LC) in the skin during delayed immune responses to tuberculin, and in the lesions of tuberculoid leprosy and cutaneous Leishmaniasis were investigated. In each situation, there was a dermal accumulation of monocytes and T cells and epidermal thickening with keratinocyte Ia expression. In the tuberculin response a dramatic change in the distribution of LC was observed. By 41 h, T6+ LC were displaced to the upper zone of the thickening epidermis followed by an almost complete loss of LC from the epidermis by approximately 72 h. After 7 d, T6+ cells started to reappear in the epidermis, which regained almost normal numbers of T6+ LC by 14 d. After antigen administration and initiation of the delayed immune response, enhanced numbers of T6+ cells appeared in association with the mononuclear cell infiltrate of the upper dermal lesions. Their numbers peaked by 72 h, were reduced at 7 d, and again enhanced by 14 d, when the epidermis was being repopulated. Similar numbers of T6+ cells were found in the chronic lesions of tuberculoid leprosy and cutaneous Leishmaniasis but not lepromatous leprosy. The cells of the dermis were identified as typical LC by the presence of Birbeck granules and surface T6 antigen at the electron microscope level. These cells were closely associated with lymphocytes. We have quantified the number of LC, evaluated their directional flux into the epidermis and dermis, determined nearest neighbors, and made predictions as to their fate

Characteristics of Mountain Lion Bed, Cache and Kill Sites In Northeastern Oregon

We described mountain lion (Puma concolor) habitat characteristics during two studies in the same area of northeastern Oregon during the 1990s. In the first study (1992-1994) we evaluated micro-habitat features associated with 61 diurnal bed sites that were not associated with kills. We used similar techniques in the second study (1996- 1998) to evaluate habitat features at 79 cache sites near lion-killed prey. A dog was used to find 93% of the diurnal bed sites. Radio telemetry triangulation was used in the second study. Characteristics of diurnal bed sites and cache sites were compared with random habitat plots. Rock structure and downed logs were identified as important habitat components at diurnal bed sites. Canopy cover at cache sites was significantly higher than at random sites. Cache sites also were associated with rock structure, but not to the same degree as diurnal bed sites. In both studies mountain lions used sites in close proximity to habitat edges more frequently than expected based on random plots. Understanding the similarities and differences of habitat use at diurnal bed, cache and kill sites sheds light on the ecological adaptation of mountain lions to the multiple environmental influences and disturbances of managed forests

RAPTOR USE OF ARTIFICIAL PERCHES AT NATURAL AREAS, CITY OF FORT COLLINS, COLORADO

The black-tailed prairie dog (Cynomys ludovicianus) remains a critical element of the prairie ecosystem even though its numbers and occupied range have declined dramatically since the arrival of Europeans in North America (Antol in et al. 2002). Prairie dog colonies are used by many species of wildlife and help maintain high levels of biodiversity (Kotliar et al. 1999). In the urban-suburban setting, the occurrence of prairie dog colonies also provides opportunities for wildlife viewing and environmental education. Unfortunately, prairie dogs also can come into conflict with humans, especially in the urban-suburban setting, where they cause vegetation and property damage, and pose a health threat attributable to periodic plague (Yersinia pestis) outbreaks (Witmer et al. 2003). Efforts to reduce conflicts can involve colony relocation or management so that the prairie dog population and occupied area does not increase (e.g., lethal or non-lethal removal, construction of physical barriers around the colony; Witmer et al. 2003). frtificial perches, placed at prairie dog colonies, can attract raptors, while providing for public viewing of raptors. The artificial perches, if strategically placed, also might increase predation on prairie dogs, slowing the increase in the size of the colony (Witmer et al. 2003). This approach has been used in other settings in an attempt to reduce rodent populations or damage, but most researchers reported little success in rodent control (e.g., Howard et al. 1985, Askham 1990, Moore and Van Vuren 1998, Wolff et al. 1999). A few researchers, however, reported that increased use of artificial perches might help reduce rodent numbers and damage (e.g., Kay et al. 1994, Mulner 2000, Hafidzi and Mohd 2003). In our region, this management practice might be especially effective given the paucity of trees (i.e., natural perches) in the shortgrass prairie outside riparian systems (Weaver et al. 1996). The objective of this study was to document the use of artificial perches by raptors and the food habits of these raptors within the city limits of Fort Collins, Colorado

RAPTOR USE OF ARTIFICIAL PERCHES AT NATURAL AREAS, CITY OF FORT COLLINS, COLORADO

The black-tailed prairie dog (Cynomys ludovicianus) remains a critical element of the prairie ecosystem even though its numbers and occupied range have declined dramatically since the arrival of Europeans in North America (Antol in et al. 2002). Prairie dog colonies are used by many species of wildlife and help maintain high levels of biodiversity (Kotliar et al. 1999). In the urban-suburban setting, the occurrence of prairie dog colonies also provides opportunities for wildlife viewing and environmental education. Unfortunately, prairie dogs also can come into conflict with humans, especially in the urban-suburban setting, where they cause vegetation and property damage, and pose a health threat attributable to periodic plague (Yersinia pestis) outbreaks (Witmer et al. 2003). Efforts to reduce conflicts can involve colony relocation or management so that the prairie dog population and occupied area does not increase (e.g., lethal or non-lethal removal, construction of physical barriers around the colony; Witmer et al. 2003). frtificial perches, placed at prairie dog colonies, can attract raptors, while providing for public viewing of raptors. The artificial perches, if strategically placed, also might increase predation on prairie dogs, slowing the increase in the size of the colony (Witmer et al. 2003). This approach has been used in other settings in an attempt to reduce rodent populations or damage, but most researchers reported little success in rodent control (e.g., Howard et al. 1985, Askham 1990, Moore and Van Vuren 1998, Wolff et al. 1999). A few researchers, however, reported that increased use of artificial perches might help reduce rodent numbers and damage (e.g., Kay et al. 1994, Mulner 2000, Hafidzi and Mohd 2003). In our region, this management practice might be especially effective given the paucity of trees (i.e., natural perches) in the shortgrass prairie outside riparian systems (Weaver et al. 1996). The objective of this study was to document the use of artificial perches by raptors and the food habits of these raptors within the city limits of Fort Collins, Colorado