Evaluation of reduced-tillering (tin) wheat lines in managed, terminal water deficit environments.

Small or shrivelled wheat kernels (screenings) that reduce crop value are commonly produced in terminal drought environments. The aim of this study was to establish whether the incorporation of the tiller inhibition (tin) gene would contribute to maintenance of kernel weight and reductions in screenings under terminal water deficit. Five Silverstar near-isogenic lines contrasting in high and low tiller potential and their recurrent Silverstar parent were established at two plant densities under managed terminal water deficit (mild and severe) and irrigated conditions. With irrigation (grain yield of 5.6 t ha(-1)), kernels of all lines weighed ~31 mg, with restricted-tillering (R-tin) lines producing an average 15% lower grain yield. Under both mild and severe terminal water deficit (4.1 t ha(-1) and 2.8 t ha(-1)), free-tillering lines had relatively high screenings ranging from 11.9% to 16.2%. Compared with free-tillering lines, R-tin lines maintained large kernel weight (~29 mg kernel(-1)) and had 29% and 51% fewer screenings under the two stresses, and a significantly greater (+11%) grain yield under mild stress. Higher kernel weights in tin lines were realized even with the greater kernel number per spike. The higher kernel weight of the R-tin lines under stress conditions was associated with greater anthesis biomass and increased stem water-soluble carbohydrates, ensuring more assimilate for later translocation to filling grain. The incorporation of the tin gene into genetic material adapted to the target environments provides scope for improvement in both grain yield and kernel weight, and a reduction in screenings in terminal water deficit environments.

Teleoperation in surgical robotics--network latency effects on surgical performance.

A teleoperated surgical robotic system allows surgical procedures to be conducted across long distances while utilizing wired and wireless communication with a wide spectrum of performance that may affect the outcome. An open architecture portable surgical robotic system (Raven) was developed for both open and minimally invasive surgery. The system has been the subject of an intensive telesurgical experimental protocol aimed at exploring the boundaries of the system and surgeon performance during a series of field experiments in extreme environments (desert and underwater) teleportation between US, Europe, and Japan as well as lab experiments under synthetic fixed time delay. One standard task (block transfer emulating tissue manipulation) of the Fundamentals of Laparoscopic Surgery (FLS) training kit was used for the experimental protocol. Network characterization indicated a typical time delay in the range of 16-172 ms in field experiments. The results of the lab experiments showed that the completion time of the task as well as the length of the tool tip trajectory significantly increased (alpha< 0.02) as time delay increased in the range of 0-0.5 sec increased. For teleoperation with a time delay of 0.25s and 0.5s the task completion time was lengthened by a factor of 1.45 and 2.04 with respect to no time delay, whereas the length of the tools' trajectory was increased by a factor of 1.28 and 1.53 with respect to no time delay. There were no statistical differences between experienced surgeons and non-surgeons in the number of errors (block drooping) as well as the completion time and the tool tip path length at different time delays.

Objective assessment of telesurgical robot systems: Telerobotic FLS.

The Society of American Gastrointestinal Endoscopic Surgeons (SAGES) Fundamentals of Laparoscopic Surgery (FLS) program contains curriculum that includes both a cognitive and psychomotor skills. In this research the use of FLS Block Transfer task is used to evaluate the performance of surgeons' teleoperating the University of Washington Surgical robot. The use of the FLS Trainer Box and accessories kit provides a well-defined series of tasks that can be repeated by any researchers working in the field of surgical robotics so that systems can be evaluated using a common method.

TeleRobotic fundamentals of laparoscopic surgery (FLS): effects of time delay--pilot study.

Within the area of telerobotic surgery no standardized means of surgically relevant performance evaluation has been established. The Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) Fundamentals of Laparoscopic Surgery (FLS) program provides a set of standardized tasks that are considered the 'gold standard' in surgical skill assessment. We present a methodology for using one of the SAGES FLS tasks for surgical robotic performance evaluation. The TeleRobotic FLS methodology is extendable to two other FLS tasks. Time delay in teleoperation in general and telesurgery in particular is one of the fundamental effects that limits performance in telerobotic surgery. In this pilot study the effect of time delay on the Block Transfer task performance was investigated. The RAVEN Surgical Robot was used in a master/slave configuration in which time delays of 0, 250, 500, and 1000 ms were introduced by a network emulator between the master (Surgeon Site) and the slave (Patient Site). The study included three subjects, each of whom was presented with three of the four conditions. The results show that one subject had a lower error rate with increasing time delay, whereas the other subjects had a higher error rate with increased delay. The subject with the longest average completion time suffered the least performance decrease under time delay.

Longitudinal-transverse separations of deep-inelastic structure functions at low Q2 for hydrogen and deuterium.

We report on a study of the longitudinal to transverse cross section ratio, R=sigmaL/sigmaT, at low values of x and Q2, as determined from inclusive inelastic electron-hydrogen and electron-deuterium scattering data from Jefferson Laboratory Hall C spanning the four-momentum transfer range 0.06

Telesurgery via Unmanned Aerial Vehicle (UAV) with a field deployable surgical robot.

Robotically assisted surgery stands to further revolutionize the medical field and provide patients with more effective healthcare. Most robotically assisted surgeries are teleoperated from the surgeon console to the patient where both ends of the system are located in the operating room. The challenge of surgical teleoperation across a long distance was already demonstrated through a wired communication network in 2001. New development has shifted towards deploying a surgical robot system in mobile settings and/or extreme environments such as the battlefield or natural disaster areas with surgeons operating wirelessly. As a collaborator in the HAPs/MRT (High Altitude Platform/Mobile Robotic Telesurgery) project, The University of Washington surgical robot was deployed in the desert of Simi Valley, CA for telesurgery experiments on an inanimate model via wireless communication through an Unmanned Aerial Vehicle (UAV). The surgical tasks were performed telerobotically with a maximum time delay between the surgeon's console (master) and the surgical robot (slave) of 20 ms for the robotic control signals and 200 ms for the video stream. This was our first experiment in the area of Mobile Robotic Telesurgery (MRT). The creation and initial testing of a deployable surgical robot system will facilitate growth in this area eventually leading to future systems saving human lives in disaster areas, on the battlefield or in other remote environments.

Optimization of a spherical mechanism for a minimally invasive surgical robot: theoretical and experimental approaches.

With a focus on design methodology for developing a compact and lightweight minimally invasive surgery (MIS) robot manipulator, the goal of this study is progress toward a next-generation surgical robot system that will help surgeons deliver healthcare more effectively. Based on an extensive database of in-vivo surgical measurements, the workspace requirements were clearly defined. The pivot point constraint in MIS makes the spherical manipulator a natural candidate. An experimental evaluation process helped to more clearly understand the application and limitations of the spherical mechanism as an MIS robot manipulator. The best configuration consists of two serial manipulators in order to avoid collision problems. A complete kinematic analysis and optimization incorporating the requirements for MIS was performed to find the optimal link lengths of the manipulator. The results show that for the serial spherical 2-link manipulator used to guide the surgical tool, the optimal link lengths (angles) are (60 degrees, 50 degrees). A prototype 6-DOF surgical robot has been developed and will be the subject of further study.

Control system architecture for a minimally invasive surgical robot.

As the field of surgical robotics continues to evolve, it is important to keep patient safety in mind. This paper describes a safety control architecture aimed at moving an experimental system in the direction of intrinsically safe operation. The system includes safety features such as: a small number of states, Programmable Logic Controller (PLC) state transition control, active enable, brakes, E-STOP, and a surgeon foot pedal.

Hybrid analysis of a spherical mechanism for a minimally invasive surgical (MIS) robot--design concepts for multiple optimizations.

Several criteria exist for determining the optimal design for a surgical robot. This paper considers kinematic performance metrics, which reward good kinematic performance, and dynamic performance metrics, which penalize poor dynamic performance. Kinematic and dynamic metrics are considered independently, and then combined to produce hybrid metrics. For each metric, the optimal design is the one that maximizes the performance metric over a specific design space. In the case of a 2-DOF spherical mechanism for a surgical robot, the optimal design determined by kinematic metrics is a robot arm with link angles (alpha(12)=90 degrees , alpha(23)=90 degrees ). The large link angles are the most dextrous, but have the greatest risk of robot-robot or robot-patient collisions and require the largest actuators. The link lengths determined by the dynamic metrics are much shorter, which reduces the risk of collisions, but tend to place the robot in singularities much more frequently. When the hybrid metrics are used, and a restriction that the arm must be able to reach a human's entire abdomen, the optimal design is around (alpha(12)=51 degrees, alpha(23)=54 degrees). The hybrid design provides a compromise between dexterity and compactness.

New insights into central cardiovascular control during exercise in humans: a central command update.

The autonomic adjustments to exercise are mediated by central signals from the higher brain (central command) and by a peripheral reflex arising from working skeletal muscle (exercise pressor reflex), with further modulation provided by the arterial baroreflex. Although it is clear that central command, the exercise pressor reflex and the arterial baroreflex are all requisite for eliciting appropriate cardiovascular adjustments to exercise, this review will be limited primarily to discussion of central command. Central modulation of the cardiovascular system via descending signals from higher brain centres has been well recognized for over a century, yet the specific regions of the human brain involved in this exercise-related response have remained speculative. Brain mapping studies during exercise as well as non-exercise conditions have provided information towards establishing the cerebral cortical structures in the human brain specifically involved in cardiovascular control. The purpose of this review is to provide an update of current concepts on central command in humans, with a particular emphasis on the regions of the brain identified to alter autonomic outflow and result in cardiovascular adjustments.

Correlated strength in the nuclear spectral function.

We have carried out an (e,e'p) experiment at high momentum transfer and in parallel kinematics to measure the strength of the nuclear spectral function S(k,E) at high nucleon momenta k and large removal energies E. This strength is related to the presence of short-range and tensor correlations, and was known hitherto only indirectly and with considerable uncertainty from the lack of strength in the independent-particle region. This experiment locates by direct measurement the correlated strength predicted by theory.

Contraction-sensitive skeletal muscle afferents inhibit arterial baroreceptor signalling in the nucleus of the solitary tract: role of intrinsic GABA interneurons.

Arterial baroreceptor and skeletal muscle receptor afferents relay sensory information to the nucleus of the solitary tract (NTS) during exercise. Previous studies have suggested that skeletal muscle afferent input inhibits baroreflex function; however, detailed information on the role of muscle afferents and GABAergic mechanisms in the NTS is limited. Furthermore, identification of specific afferent modalities that activate GABAergic neurons in the NTS remains unknown. In the present study, we examined the neuroanatomical and physiological interactions between spinal dorsal horn cells that transmit contraction-sensitive input from skeletal muscle and GABAergic interneurons in the NTS. Biotinylated dextran amine (BDA, 10%, 25-100 nL) microinjection into dorsal horn of the cervical spinal cord was combined with glutamate decarboxylase (GAD) immunohistochemistry to visualize the nature of the relationship of BDA-labeled fibers in the NTS with GAD immunoreactivity (GAD-ir). BDA-labeled axons and terminal processes were localized in the medial, commissural, dorsomedial and dorsolateral subdivisions of the caudal NTS. Moreover, BDA-labeled fibers were observed in close proximity to GAD-ir structures throughout these regions of the NTS. The physiological interaction between skeletal muscle receptor and arterial baroreceptor afferents was investigated using an arterially perfused, decerebrate rat preparation. Activation of skeletal muscle afferents by electrically evoked twitch contraction of the forelimb attenuated baroreflex responsiveness (BR, calculated as the ratio of changes in heart rate to systemic pressure) from -1.5+/-0.3 bpm.mm Hg(-1) to -0.1+/-0.1 bpm.mm Hg(-1) (control versus contraction, P<0.05, n=15). However, forelimb contraction failed to inhibit the reflex bradycardia evoked by activation of peripheral chemoreceptor afferents, indicating a reflex-specific action. Bilateral microinjection of bicuculline methiodide (BIC, 10 microM, 40-60 nL) into the caudal NTS restored baroreflex responsiveness during contraction (-1.6+/-0.2 versus -0.1+/-0.1 versus -1.5+/-0.2 bpm.mmHg(-1), control versus contraction versus contraction+BIC P<0.05, n=8). We conclude that activation of ascending spinal neurons from the cervical dorsal horn by contraction-sensitive skeletal muscle afferents selectively inhibits arterial baroreceptor signaling in the NTS via activation of a GABAergic mechanism.

Role of central command in carotid baroreflex resetting in humans during static exercise.

The purpose of the experiments was to examine the role of central command in the exercise-induced resetting of the carotid baroreflex. Eight subjects performed 30 % maximal voluntary contraction (MVC) static knee extension and flexion with manipulation of central command (CC) by patellar tendon vibration (PTV). The same subjects also performed static knee extension and flexion exercise without PTV at a force development that elicited the same ratings of perceived exertion (RPE) as those observed during exercise with PTV in order to assess involvement of the exercise pressor reflex. Carotid baroreflex (CBR) function curves were modelled from the heart rate (HR) and mean arterial pressure (MAP) responses to rapid changes in neck pressure and suction during steady state static exercise. Knee extension exercise with PTV (decreased CC activation) reset the CBR-HR and CBR-MAP to a lower operating pressure (P < 0.05) and knee flexion exercise with PTV (increased CC activation) reset the CBR-HR and CBR-MAP to a higher operating pressure (P < 0.05). Comparison between knee extension and flexion exercise at the same RPE with and without PTV found no difference in the resetting of the CBR-HR function curves (P > 0.05) suggesting the response was determined primarily by CC activation. However, the CBR-MAP function curves were reset to operating pressures determined by both exercise pressor reflex (EPR) and central command activation. Thus the physiological response to exercise requires CC activation to reset the carotid-cardiac reflex but requires either CC or EPR to reset the carotid-vasomotor reflex.

Brain activation by central command during actual and imagined handgrip under hypnosis.

The purpose was to compare patterns of brain activation during imagined handgrip exercise and identify cerebral cortical structures participating in "central" cardiovascular regulation. Subjects screened for hypnotizability, five with higher (HH) and four with lower hypnotizability (LH) scores, were tested under two conditions involving 3 min of 1) static handgrip exercise (HG) at 30% of maximal voluntary contraction (MVC) and 2) imagined HG (I-HG) at 30% MVC. Force (kg), forearm integrated electromyography, rating of perceived exertion, heart rate (HR), mean blood pressure (MBP), and differences in regional cerebral blood flow distributions were compared using an ANOVA. During HG, both groups showed similar increases in HR (+13 +/- 5 beats/min) and MBP (+17 +/- 3 mmHg) after 3 min. However, during I-HG, only the HH group showed increases in HR (+10 +/- 2 beats/min; P < 0.05) and MBP (+12 +/- 2 mmHg; P < 0.05). There were no significant increases or differences in force or integrated electromyographic activity between groups during I-HG. The rating of perceived exertion was significantly increased for the HH group during I-HG, but not for the LH group. In comparison of regional cerebral blood flow, the LH showed significantly lower activity in the anterior cingulate (-6 +/- 2%) and insular cortexes (-9 +/- 4%) during I-HG. These findings suggest that cardiovascular responses elicited during imagined exercise involve central activation of insular and anterior cingulate cortexes, independent of muscle afferent feedback; these structures appear to have key roles in the central modulation of cardiovascular responses.

Electrically induced static exercise elicits a pressor response in the decerebrate rat.

1. The purpose of this investigation was to determine if activation of the exercise pressor reflex in the decerebrate rat induced circulatory responses comparable to those reported in large mammalian species. 2. To activate both mechanically and metabolically sensitive afferent fibres, static hindlimb contractions were induced by stimulating the cut ends of L4 and L5 spinal ventral roots in Sprague-Dawley rats (300-400 g). To selectively stimulate mechanically sensitive receptors, hindlimb muscles were passively stretched. 3. In intact halothane-anaesthetized animals (n = 10), static contraction and passive stretch induced a decrease in mean arterial pressure (Delta MAP = -17 +/- 3 and -8 +/- 1 mmHg for contraction and stretch, respectively) and heart rate (HR). In contrast, MAP increased 23 +/- 2 mmHg during contraction and 19 +/- 3 mmHg during stretch in decerebrate rats (n = 10). These pressor responses were accompanied by a significant tachycardia. In decerebrate animals, the reintroduction of halothane attenuated the increase in MAP and HR caused by both contraction and stretch. 4. In both anaesthetized and decerebrate rats, sectioning the spinal dorsal roots innervating the activated skeletal muscle eliminated responses to contraction and stretch. This finding indicated that an intramuscular neural reflex mediated the response to each stimulus. 5. The results demonstrate that a decerebrate preparation in the rat is a reliable model for the study of the exercise pressor reflex. Development of the model would enable the study of this reflex in a variety of pathological conditions and allow investigation of the mechanisms controlling cardiovascular responses to exercise in health and disease.

A 30-year follow-up of the Dallas Bedrest and Training Study: I. Effect of age on the cardiovascular response to exercise.

BACKGROUND: Cardiovascular capacity declines with aging, as evidenced by declining maximal oxygen uptake (VO(2)max ), with little known about the specific mechanisms of this decline. Our study objective was to assess the effect of a 30-year interval on body composition and cardiovascular response to acute exercise in 5 healthy subjects originally evaluated in 1966. METHODS AND RESULTS: Anthropometric parameters and the cardiovascular response to acute maximal exercise were assessed with noninvasive techniques. On average, body weight increased 25% (77 versus 100 kg) and percent body fat increased 100% (14% versus 28%), with little change in fat-free mass (66 versus 72 kg). On average, VO(2)max decreased 11% (3.30 versus 2.90 L/min). Likewise, VO(2)max decreased when indexed to total body mass (43 versus 31 mL. kg(-1). min(-1)) or fat-free mass (50 versus 43 mL/kg fat-free mass per minute). Maximal heart rate declined 6% (193 versus 181 bpm) and maximal stroke volume increased 16% (104 versus 121 mL), with no difference observed in maximal cardiac output (20.0 versus 21.4 L/min). Maximal AV oxygen difference declined 15% (16.2 versus 13.8 vol%) and accounted for the entire decrease in cardiovascular capacity. CONCLUSIONS: Cardiovascular capacity declined over the 30-year study interval in these 5 middle-aged men primarily because of an impaired efficiency of maximal peripheral oxygen extraction. Maximal cardiac output was maintained with a decline in maximal heart rate compensated for by an increased maximal stroke volume. Most notably, 3 weeks of bedrest in these same men at 20 years of age (1966) had a more profound impact on physical work capacity than did 3 decades of aging.

A 30-year follow-up of the Dallas Bedrest and Training Study: II. Effect of age on cardiovascular adaptation to exercise training.

BACKGROUND: Aerobic power declines with age. The degree to which this decline is reversible remains unclear. In a 30-year longitudinal follow-up study, the cardiovascular adaptations to exercise training in 5 middle-aged men previously trained in 1966 were evaluated to assess the degree to which the age-associated decline in aerobic power is attributable to deconditioning and to gain insight into the specific mechanisms involved. Methods and Results-- The cardiovascular response to acute submaximal and maximal exercise were assessed before and after a 6-month endurance training program. On average, VO(2max) increased 14% (2.9 versus 3.3 L/min), achieving the level observed at the baseline evaluations 30 years before. Likewise, VO(2max) increased 16% when indexed to total body mass (31 versus 36 mL/kg per minute) or fat-free mass (44 versus 51 mL/kg fat-free mass per minute). Maximal heart rate declined (181 versus 171 beats/min) and maximal stroke volume increased (121 versus 129 mL) after training, with no change in maximal cardiac output (21.4 versus 21.7 L/min); submaximal heart rates also declined to a similar degree. Maximal AVDO(2) increased by 10% (13.8 versus 15.2 vol%) and accounted for the entire improvement of aerobic power associated with training. CONCLUSIONS: One hundred percent of the age-related decline in aerobic power among these 5 middle-aged men occurring over 30 years was reversed by a 6-month endurance training program. However, no subject achieved the same maximal VO(2) attained after training 30 years earlier, despite a similar relative training load. The improved aerobic power after training was primarily the result of peripheral adaptation, with no effective improvement in maximal oxygen delivery.

Effect of a phytoestrogen food supplement on reproductive health in normal males.

Animal studies and human intervention trials have demonstrated the cancer chemopreventive properties of plant phytoestrogens, and phytoestrogen supplements are now widely available 'over-the-counter'. However, consumption of phytoestrogen-rich diets can cause impaired fertility and reproductive tract disorders in some animals and the apparent decline in human sperm quality over recent decades may be related to increased exposure to environmental endocrine disruptors. The present study determines the effects of a short-term phytoestrogen supplement on semen quality and serum sex steroid and gonadotrophin levels in human males. Healthy volunteers took a supplement containing 40 mg of isoflavones daily for 2 months and donated blood and semen samples monthly for 2 months before and 4 months after supplementation. Semen samples were analysed for ejaculate volume, sperm concentration, total sperm count, motility and morphology. Blood samples were analysed for sex hormone and gonadotrophin levels and phytoestrogen concentrations, and testicular volume was measured using an orchidometer. The phytoestrogen supplement increased plasma genistein and daidzein concentrations to approx. 1 microM and 0.5 microM respectively; yet, there was no observable effect on endocrine measurements, testicular volume or semen parameters over the study period. This is the first study to examine the effects of a phytoestrogen supplement on reproductive health in males. We conclude that the phytoestrogen dose consumed had no effect on semen quality.

Search for quadrupole strength in the electroexcitation of the delta+(1232).

High-precision 1H(e,e'p)pi(0) measurements at Q2 = 0.126 (GeV/c)2 are reported, which allow the determination of quadrupole amplitudes in the gamma*N-->Delta transition; they simultaneously test the reliability of electroproduction models. The derived quadrupole-to-dipole ( I = 3/2) amplitude ratios, R(SM) = (-6.5+/-0.2(stat+sys)+/-2.5(mod))% and R(EM) = (-2.1+/-0.2(stat+sys)+/-2.0(mod))%, are dominated by model error. Previous R(SM) and R(EM) results should be reconsidered after the model uncertainties associated with the method of their extraction are taken into account.