ABSTRACT
Behavioral and kinematic properties and capacities of wild migratory salmonid fishes swimming upstream and jumping up waterfalls generally have played only minor roles in the design and construction of passageways intended to help these fishes get past dams and other human-made obstacles blocking their movements. This paper reports the results of an experimental study of relevant behavioral and kinematic properties of adult kokanee salmon (Oncorhynchus nerka) jumping up waterfalls as they migrate upstream. We used a portable, adjustable apparatus to study in the field fish responding to artificial waterfalls under a range of flow conditions. We observed fish under conditions of varying water flow rates, pool depths, fall heights and fall angles. We analyzed digital video recordings of their behaviors. Kokanee salmon spontaneously jump up waterfalls within a relatively narrow range of conditions, including low flow speeds, near vertical angles and pool depth to fall height ratios near 1.0. Preferred values for each parameter are, to some extent, dependent on other parameters. In contrast to previous misconceptions, jumping behavior is initiated by running S-start accelerations from beneath the boils formed in the plunge pools below waterfalls, as opposed to C-start standing jumps from the surface. S-starts are immediately followed by burst swimming to the point of takeoff at the surface. These results can contribute to an improved basis for developing designs of fish passageways that may ultimately make them more effective and efficient.
Subject(s)
Animal Migration/physiology , Environment Design , Salmon/physiology , Animals , Biomechanical Phenomena , Biomimetics , Calibration , Hydrodynamics , Video RecordingABSTRACT
It has long been recognized that the first and second lumbricals are normally innervated by the median nerve, whereas the third and fourth lumbricals are innervated by the ulnar nerve (Sunderland and Ray, 1946). However, the courses of the motor nerves, particularly to the first two lumbricals and their loci of insertion, have not been clearly described. Because this information may be useful to a surgeon operating in the palm, we undertook a cadaver study to define more precisely the pathways of innervation of the lumbrical muscles.
Subject(s)
Median Nerve/anatomy & histology , Muscle, Skeletal/innervation , Ulnar Nerve/anatomy & histology , Cadaver , Fingers , HumansABSTRACT
Prostaglandin E2 (PGE2) has been shown to stimulate both bone resorption and formation in experimental animals, leading to augmentation of trabecular and cortical bone. The amino bisphosphonate alendronate (ALN) is a potent inhibitor of bone resorption. The objectives of this study were to examine if PGE2 stimulation of bone formation was dependent on bone resorption and if the bone accrued as a result of PGE2 treatment contributed to bone strength. The 48 female Sprague-Dawley rats were assigned to six groups as follows: five groups (8/group) were ovariectomized at the age of 6 months. One group was sacrificed 2 months later to establish baseline conditions, and four groups were treated for 25 days with (1) vehicle, (2) PGE2 at 3 mg/kg/day, (3) ALN sc at 0.8 micrograms/kg/day, and (4) PGE2 + ALN at the respective doses. The sixth group served as nonovariectomized untreated controls. Histomorphometric analysis of 6-10 microns thick tibial sections after in vivo fluorochrome double labeling showed that treatment with PGE2 alone increased endocortical mineral apposition rate and bone formation rate, stimulated production of bone trabeculae in the marrow cavity, and increased cortical porosity. Combined ALN + PGE2 treatment prevented the resorption induced by PGE2 but not the stimulation of bone formation on endocortical and periosteal surfaces and resulted in a significant increase in cortical thickness. Consistent with these observations, the femoral midshaft tested to failure in three-point bending showed a significant increase in strength in the PGE2 + ALN group (181 +/- 15 N) compared to time 0 controls (145 +/- 23 N) or to the ovariectomized vehicle-treated group (141 +/- 28 N).(ABSTRACT TRUNCATED AT 250 WORDS)
Subject(s)
Bone Development/drug effects , Bone Resorption , Bone and Bones/drug effects , Dinoprostone/pharmacology , Diphosphonates/pharmacology , Alendronate , Animals , Biomechanical Phenomena , Bone Density/drug effects , Bone and Bones/anatomy & histology , Bone and Bones/physiology , Drug Interactions , Female , Femur , Hindlimb , Lumbar Vertebrae , Ovariectomy , Rats , Rats, Sprague-Dawley , SoftwareABSTRACT
The biocompatibility of a new elastomeric-hydrogel matrix biomaterial for use as an intravasal occlusive device was assessed by inserting it into the vas deferens of dogs. The vas was removed and examined histologically after varying periods of time. The biomaterial resulted in total occlusion of the vas. Epithelial changes were limited to squamous metaplasia in areas adjacent to the implant. Changes in the subepithelium were minimal. This new material is biocompatible with the dog vas, and it has potential as an occlusive device for "reversible" vasectomy in men. Semen analysis studies are needed to assess the completeness and reversibility of the vasal occlusion achieved with this implant.