Tackling social determinants of health through community based initiatives.
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Community Health Planning↗
Biomedical subjects
S Watts
Publications and source records attributed to S Watts.
Comparison of kinematics in skilled and unskilled arms of the same recreational baseball players.
We examined mechanisms of coordination that enable skilled recreational baseball players to make fast overarm throws with their skilled arm and which are absent or rudimentary in their unskilled arm. Arm segment angular kinematics in three dimensions at 1000 Hz were recorded with the search-coil technique from the arms of eight individuals who on one occasion threw with their skilled right arm and on another with their unskilled left arm. Compared with their unskilled arm, the skilled arm had: a larger angular deceleration of the upper arm in space in the forward horizontal direction; a larger shoulder internal rotation velocity at ball release (unskilled arms had a negative velocity); a period of elbow extension deceleration before ball release; and an increase in wrist velocity with an increase in ball speed. It is suggested that some of these differences in arm kinematics occur because of differences between the skilled and unskilled arms in their ability to control interaction torques (the passive torque at one joint due to motion at adjacent joints). It is proposed that one reason unskilled individuals cannot throw fast is that, unlike their skilled counterparts, they have not developed the coordination mechanisms to effectively exploit interaction torques.
Acceleration↗
Two-stage thermophilic-mesophilic anaerobic digestion of waste activated sludge from a biological nutrient removal plant.
A two-stage thermophilic-mesophilic anaerobic digestion pilot-plant was operated solely on waste activated sludge (WAS) from a biological nutrient removal (BNR) plant. The first-stage thermophilic reactor (HRT 2 days) was operated at 47, 54 and 60 degrees C. The second-stage mesophilic digester (HRT 15 days) was held at a constant temperature of 36-37 degrees C. For comparison with a single-stage mesophilic process, the mesophilic digester was also operated separately with an HRT of 17 days and temperature of 36-37 degrees C. The results showed a truly thermophilic stage (60 degrees C) was essential to achieve good WAS degradation. The lower thermophilic temperatures examined did not offer advantages over single-stage mesophilic treatment in terms of COD and VS removal. At a thermophilic temperature of 60 degrees C, the plant achieved 35% VS reduction, representing a 46% increase compared to the single-stage mesophilic digester. This is a significant level of degradation which could make such a process viable in situations where there is no primary sludge generated. The fate of the biologically stored phosphorus in this BNR sludge was also investigated. Over 80% of the incoming phosphorus remained bound up with the solids and was not released into solution during the WAS digestion. Therefore only a small fraction of phosphorus would be recycled to the main treatment plant with the dewatering stream.
Anaerobiosis↗
Braking of elbow extension in fast overarm throws made by skilled and unskilled subjects.
A previous computer simulation study of overarm throws in 2D showed that reversal of elbow torque by antagonist muscle action late in the throw led to increased wrist flexion velocity and to increased ball speeds. We tested the hypothesis that the skill of making fast overarm throws in 3D involves deceleration (braking) of elbow extension before ball release, and that this is an active mechanism. Skilled and unskilled throwers were instructed to throw baseballs at a fast speed. Arm segment angular positions in 3D at 1,000 Hz were recorded with the search-coil technique (which records angular motions). In skilled throws, but not in unskilled throws, there was a period (mean 17 ms) of rapid elbow extension deceleration before ball release. However, there was relatively little biceps EMG activity associated with the very large magnitude of elbow deceleration. This finding and other work suggests that elbow extension deceleration results in part from interaction torques associated with late-occurring shoulder rotations, and only in part from elbow flexor contraction. During the period when elbow extension was decelerating, the forearm in space was undergoing angular acceleration (because of internal rotation at the shoulder) which would be expected to produce a torque at the wrist in the extensor (not flexor) direction. The results show that elbow extension deceleration occurs before ball release in fast (skilled) 3D throws, and that it does not produce forearm angular deceleration. Whether it produces forearm translational deceleration, which could increase wrist flexion velocity, remains to be determined.
Adult↗
Timing of ball release in overarm throws affects ball speed in unskilled but not skilled individuals.
We tested the hypothesis that variability in the timing of ball release in overarm throws affects ball speed. Nine unskilled and six skilled throwers made 30 throws fast and accurately from a sitting and standing position. Angular positions of finger and arm segments were recorded with search-coils at 1000 Hz; ball speed was measured with a radar gun. The time of ball release from the fingertips was measured with respect to seven arm kinematic reference points. Mean timing windows for ball release were 28 ms for unskilled throwers and 7 ms for skilled throwers. Mixed-model analyses of variance showed that a there was a statistically significant relationship between ball speed and the timing of ball release in unskilled throwers, but not in skilled throwers. This was presumably due to the difference in variability of the timing of ball release between the two groups. In contrast, skilled throwers showed a relationship between ball speed and peak forearm angular velocity (one measure of arm speed). We conclude that although variability in the timing of ball release can affect ball speed, this is only a major factor in unskilled throwers. When skilled throwers throw fast, variability in ball speed is due to variability in arm speed.
Adult↗
Experience of domestic violence by women attending an inner city accident and emergency department.
OBJECTIVES: To identify the prevalence of domestic violence (DV) (defined as physical abuse perpetrated by intimate partners) in women attending an inner city accident and emergency department and to elicit women's response about being asked routinely about domestic violence in this setting. METHODS: 22 nursing shifts were purposefully sampled to be representative of day, night, and weekends. A questionnaire was administered to 198 consenting women who were not intoxicated, confused, or critically ill. RESULTS: The prevalence of acute trauma in women attributable to DV was 1% (95%CI 0.14 to 3.6), the prevalence of lifetime physical abuse was 34.8% (95%CI 28.2 to 41.5), of past year physical abuse was 6.1% (95%CI 3.2 to 10.3), and of lifetime life threatening physical abuse was 10.6% (95%CI 6.3 to 14.9). Seventy six per cent of women felt comfortable about being asked about DV and 60.5% of women felt that they should always or usually be asked about DV in this setting. CONCLUSION: This cross sectional survey adds to the body of knowledge showing that the prevalence of DV in women attending an accident and emergency department is high. Most women were in favour of being asked, and disclosure was associated with discomfort in few women. This sensitive area of history taking and referral could be undertaken by health professionals using a supportive approach.
Adolescent↗
Kinematics of wrist joint flexion in overarm throws made by skilled subjects.
Previous studies of multijoint arm movements have shown that the CNS holds arm kinematics constant in different situations by predictively compensating for the effects of interaction torques. We determined whether this was also the case for wrist joint flexion in natural overarm throws performed by skilled subjects in 3D, a situation where large passive torques can occur at the wrist. Specifically, we investigated whether wrist flexion amplitudes are held constant in throws of different speeds. Joint rotations were recorded at 1,000 Hz with the search-coil technique. Contrary to a previous study on constrained 2D throwing, indirect evidence was found that in fast throws passive torques associated with forearm deceleration were exploited to increase wrist flexion velocity. This increase in wrist flexion velocity was associated with constant wrist flexion amplitudes at ball release (mean 27 degrees) for throws of different speeds. Furthermore, final wrist flexion positions after ball release were similar for a particular subject irrespective of the speed of the throw. This was associated in faster throws with increased magnitudes of wrist flexor and wrist extensor EMG activity which damped passive torques associated with forearm angular deceleration. It is concluded that wrist flexion in overarm throws of different speeds is produced by central signals which precisely control net joint torque by both exploiting and damping passive torques during different parts of the throw to keep wrist joint angular position parameters constant. As such the results show that control strategies for natural 3D throwing are different from those for constrained 2D throwing.
Arm↗
Overarm throwing speed in cerebellar subjects: effect of timing of ball release.
Cerebellar subjects cannot throw fast and show variability in ball speed from throw to throw. One possible reason is that they release the ball at times when arm speed is not at its maximal value. Therefore, we investigated the hypothesis that the slow and variable speeds of throws made by cerebellar subjects are caused by their known large variability in the timing of ball release. Eight cerebellar subjects and matched controls were instructed to make overarm throws fast and accurately. Angular positions of arm segments were recorded with search coils at 1,000 Hz. Timing of ball release was measured with respect to the time of occurrence of seven arm kinematic reference points. All cerebellar subjects showed strong relations between ball speed and the timing of ball release, with faster ball speeds associated with late ball release. In agreement, faster ball speeds were also associated with longer hand paths to ball release, and with balls which went low on the target. However, when timing of ball release was optimal for achieving maximal ball speed in the cerebellar subjects, their fastest ball speeds were on average only 67% those of controls. Similarly, peak forearm angular velocity (one measure of arm speed) in the cerebellar group was 58% that of the control group. It is concluded that the large variability in timing ball release in cerebellar subjects contributes to their variability in ball speed, but is only a minor factor in their inability to throw fast. The major reason why cerebellar subjects do not throw fast is that they do not generate fast arm speeds.
Adolescent↗
Health visiting at the crossroads: which way to the 21st century?
This article presents a response from a group of lecturers at Florence Nightingale School of Nursing and Midwifery, King's College London and one service user to the perception of a crisis of confidence within health visiting. Changes in registration procedures and shifts in policy have led health visiting to question its place within primary care and the model of preparation for health visiting practice. The group argues that this debate is based on a misunderstanding of the changing health care environment and that health visiting can find a place within the primary care team. Key to this is the continued adherence to a basic nursing training. The authors suggest an incremental model of health visitor training to provide the fullest scope to implement the new health agenda.
Attitude of Health Personnel↗
Disorders in timing and force of finger opening in overarm throws made by cerebellar subjects.
Although there is agreement that an important sign of cerebellar dysfunction is disorder in timing of movement, it appears that authors who study different behaviors mean different things when they use the term "timing," and that the underlying mechanisms are likely to be different. For overarm throwing, skilled throwers can time ball release with a precision of less than 7 ms, whereas cerebellar subjects show a large variability of 50 ms or more in this timing. Furthermore, cerebellar patients show a larger variability in the amplitude of finger opening which could either reflect a disorder in force, or result indirectly from the increased variability in timing. To determine whether timing and force of finger opening were dependent variables, the time of ball release was plotted against the amplitude of finger opening. In control subjects these two parameters were related, with early (mistimed) throws having smaller finger amplitudes. However, in cerebellar subjects the increased variability in finger amplitude could not be accounted for by the increased variability in timing. Similarly, the increased timing windows could not be explained by disorder in force at the fingers. It is concluded that the abnormal finger opening that occurs in cerebellar patients when making overarm throws results from increased variability in both the timing and force of finger extension. Whether the increased variability in timing is a disorder in triggering finger opening at the right moment, or is due to a failure to combine finger opening appropriately with the hand trajectory, remains to be determined.
Arm↗
Physiological compensation in unilateral eyestalk ablated crayfish, Cherax quadricarinatus.
The eyestalks of crustaceans contain neurosecretory cells involved in the regulation of molting. In crayfish, bilateral ablation results in increased molting frequency and weight gain whereas unilateral ablation typically has no effect on molting frequency and weight gain. The effects of unilateral ablation were examined in juvenile Australian freshwater crayfish, Cherax quadricarinatus. As observed for other crayfish species, molting frequency and weight gain of unilateral ablated crayfish were not significantly different from control (intact) crayfish. Survival of unilateral ablated crayfish, however, was reduced compared to controls and was likely due to stress associated with the surgical procedure itself. Using radiolabeling techniques, protein synthesis was determined for neural tissues from the remaining eyestalk of ablated crayfish and compared to protein synthesis of neural tissues from eyestalks of control, non-ablated crayfish. Protein synthesis of ablated crayfish neural tissues was significantly higher (ca. 45%) than protein synthesis of control neural tissues. Electrophoretic analysis (SDS-PAGE and autoradiography) further demonstrated that protein synthesis increased linearly for all proteins in the remaining eyestalk of ablated crayfish. Together, these results suggest that a compensatory response occurred in unilateral ablated crayfish allowing normal physiological functions, particularly those involved in regulating growth cycles, to be maintained. J. Exp. Zool. 289:184-189, 2001.
Adaptation, Physiological↗
L-NAME, a nitric oxide synthase inhibitor, as a potential countermeasure to post-suspension hypotension in rats.
A large number of astronauts returning from spaceflight experience orthostatic hypotension. This hypotension may be due to overproduction of vasodilatory mediators, such as nitric oxide (NO) and prostaglandins. To evaluate the role of the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) as a countermeasure against the post-suspension reduction in mean arterial pressure (MAP), we assessed the cardiovascular responses and vascular reactivity to 7-day 30 degrees tail-suspension and a subsequent 6 hr post-suspension period in conscious rats. After a pre-suspension reading, direct MAP and heart rate (HR) were measured daily and every 2 hrs post-suspension. The NO synthase inhibitor L-NAME (20 mg/kg, i.v.), or saline, were administered after the 7th day reading prior to release from suspension and at 2 and 4 hrs post-suspension. At 6 hrs post-suspension, vascular reactivity was assessed. While MAP did not change during the suspension period, it was reduced post-suspension. Heart rate was not significantly altered. L-NAME administration reversed the post-suspension reduction in MAP. In addition, the baroreflex sensitivity for heart rate was modified by L-NAME. Thus, the post-suspension reduction in MAP may be due to overproduction of NO and altered baroreflex activity.
Animals↗
Experience of 'screening' for domestic violence in women's services.
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Attitude of Health Personnel↗
Decreased vascular glucose transporter expression and glucose uptake in DOCA-salt hypertension.
OBJECTIVE: Because glucose uptake and metabolism can affect vascular smooth muscle cell function, we proposed that animals with hypertension might develop alterations in glucose transporter expression in vascular smooth muscle cells that were responsible for some of the vascular abnormalities characteristic of hypertension. DESIGN AND METHOD: Male Sprague-Dawley rats (250-300 g) were left uni-nephrectomized and either implanted or not with deoxycorticosterone acetate (DOCA, 200 mg/kg) impregnated silastic. All animals were fed normal rat chow. The DOCA-implanted rats were given water supplemented to 1% NaCl and 0.2% KCl for 7, 14 or 28 days. RESULTS: The insulin-response glucose transporter (GLUT4) polypeptide levels were depressed several-fold in aortae and carotid arteries from DOCA-salt hypertensive rats compared with sham rats. Uptake of the glucose analog, 2-deoxyglucose (2-DOG), was also reduced 53% in hypertensive compared with sham aortae. There were no changes in GLUT4 expression in other tissues in the DOCA-salt animals, nor were there significant changes in aortae from spontaneously hypertensive rat/stroke prone animals. As previously demonstrated, carotid arteries from DOCA-salt animals exhibited a significant increased contractile sensitivity to ergonovine. Inhibition of glucose metabolism with 2-DOG in sham arteries caused a marked enhancement of contractile responsiveness to ergonovine, whereas 2-DOG had no effect on the already enhanced contractility of DOCA-salt arteries, suggesting that reduction in glucose uptake and metabolism substantially increases the contractile response of DOCA-salt arteries. CONCLUSIONS: Alterations in glucose uptake and metabolism in vascular smooth muscle cells may participate in the contractile abnormalities characteristic of certain forms of hypertension.
Animals↗
Nitric oxide-independent effects of tempol on sympathetic nerve activity and blood pressure in normotensive rats.
The role of the sympathetic nervous system in 4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl (tempol)-induced cardiovascular responses in urethane-anesthetized, normotensive rats was evaluated. Tempol caused dose-dependent (30-300 micromol/kg iv) decreases in renal sympathetic nerve activity (RSNA), mean arterial blood pressure (MAP), and heart rate (HR). Similar responses were obtained after sinoaortic denervation and cervical vagotomy. These responses were not blocked following treatment with the nitric oxide synthase inhibitor NG-nitro-L-arginine (2.6 mg x kg(-1) x min(-1) iv for 5 min) or the alpha2-adrenergic receptor antagonist idazoxan (0.3 mg/kg iv bolus). Idazoxan blocked the effects of clonidine (10 miccrog/kg iv) on HR, MAP, and RSNA. Hexamethonium (30 mg/kg iv) inhibited RSNA, and tempol did not decrease RSNA after hexamethonium. The effects of tempol on HR and MAP were reduced by hexamethonium. In conclusion, depressor responses caused by tempol are mediated, partly, by sympathoinhibition in urethane-anesthetized, normotensive rats. Nitric oxide does not contribute to this response, and the sympathoinhibitory effect of tempol is not mediated via alpha2-adrenergic receptors. Finally, tempol directly decreases HR, which may contribute to the MAP decrease.
Animals↗
Control of finger grip forces in overarm throws made by skilled throwers.
In an overarm throw, as the hand opens and the ball rolls along the fingers, the ball exerts a back force on the fingers. Previous studies suggested that skilled throwers compensate for this back force by producing an appropriate finger flexor torque to oppose the back force, but it was unclear how this is controlled by the CNS. We investigated whether the increase in finger flexor torque is timed precisely to occur late in the throw as the fingers open or whether the increase occurs throughout the throw to anticipate the increase in hand acceleration. Recreational ball players threw balls of different weights and diameters at different speeds from both a sitting and standing position while arm joint rotations were recorded with the search-coil technique. Force transducers were taped to the distal and middle phalanges of the middle finger and subjects released the ball from this finger. Passive forces on the finger were also recorded in "fake" throws in which the ball was taped to the finger and subjects did not grip the ball. These skilled throwers correctly anticipated the magnitude of the back force from the ball on the finger because the mean amplitude of finger extension did not increase in throws made with a large range of increasing back forces. This was achieved by subjects gripping the ball during the backswing with a force proportional to ball weight and intended ball speed (acceleration) and progressively increasing the grip force throughout the backswing and forward throw. The magnitude of this grip force during the forward throw was not affected by ball texture. After ball release from the fingertip, the finger flexed in proportion to the peak force on the finger before ball release. It is concluded, in a skilled fast overarm throw where large, fast-changing forces on the fingers result from the sum of motions at all arm joints, that finger flexor torque is progressively increased throughout the throw in an anticipatory (predictive) fashion to counteract the progressively increasing back force from the ball.
Adult↗
Increased variability in finger position occurs throughout overarm throws made by cerebellar and unskilled subjects.
We investigated the ability of cerebellar patients and unskilled subjects to control finger grip position and the amplitude of finger opening during a multijoint overarm throw. This situation is of interest because the appropriate finger control requires predicting the magnitude of back forces from the ball on the finger throughout the throw and generating the appropriate level and rate of change of finger flexor torque to oppose the back force. Cerebellar patients, matched controls, and unskilled subjects threw tennis balls and tennis-sized balls of different weights. In all cases angular positions of five arm segments in three dimension were recorded at 1,000 Hz with the search-coil technique as subjects threw from a seated position. When the hand was stationary, cerebellar patients showed a normal ability to grip the ball and open the fingers and drop the ball. In contrast, in overarm throws where a back force occurred on the fingers, cerebellar patients showed an abnormally large variability in amplitude of the change in finger position when gripping, in amplitude of finger opening, and in amplitude of the change in finger position 10 ms after ball release. This was not due to more trial-to-trial variation in throwing speed. When throwing balls of increasing weights, both controls and cerebellar patients had increasing finger flexions after ball release that indicated that, on average, both scaled finger force in proportion to ball weight during the throw. Unlike skilled controls, cerebellar patients showed a small (<20 degrees ) increase in the amplitude of finger opening with balls of increasing weight. However, neither the increase in variability of finger position nor the increase in finger amplitude with balls of increasing weight were unique cerebellar signs because both were observed to various degrees in unskilled throwers. It is concluded that in the absence of either normal cerebellar function or skill, the central neural activity that controls finger opening in throwing can increase finger flexor force to oppose an increase in back force from heavier balls and can open the fingers but cannot control finger force or finger opening precisely and consistently from throw to throw. These results fit with the idea that cerebellar disorders are greater in multijoint than single-joint movements because control of force is more complicated. They are also consistent with the hypothesis that the cerebellum produces skill in movement by reducing variability in the timing and force of muscle contractions.
Adolescent↗
Exceptionally high-rate nitrification in sequencing batch reactors treating high ammonia landfill leachate.
The nitrogen removal capacity of a suspended culture system treating mature landfill leachate was investigated. Leachate containing high ammonium levels of 300-900 mg N/L was nitrified in a bench scale sequencing batch reactor. Leachate from four different landfills was treated over a two year period for the removal of nitrogen. In this time, a highly specific nitrifying culture was attained that delivered exceptionally high rates of ammonia removal. No sludge was wasted from the system to increase the throughput and up to 13 g/L of MLSS was obtained. Settleability of the purely nitrifying biomass was excellent with SVI less than 40 mL/g, even at the high sludge concentrations. Nitrification rates up to 246 mg N/(L h) (5.91 g N/(L d)) and specific nitrification rates of 36 mg N/(gVSS h) (880 mg N/(gVSS d)) were obtained. The loading to the system at this time allowed complete nitrification of the leachate with a hydraulic retention time of only 5 hours. Following these successful treatability studies, a full-scale plant was designed and built at one of the landfills investigated.
Ammonia↗