A closed-loop jacobian transpose scheme for solving the inverse kinematics of nonredundant and redundant wrists

The solution of the inverse kinematic problem is of the utmost importance in robotic manipulator control. This article proposes a closed-loop scheme for solving the inverse kinematic problem for nonredundant and redundant wrists based on the computation of the Jacobian transpose. The manipulability measure is suitably introduced as a constraint for redundant wrists, by taking advantage of the null space of the Jacobian matrix. The resulting algorithm provides a computational tool to solve a specified orientation trajectory into a joint trajectory. Numerical results with two spherical wrists show the excellent performance of the scheme.     

A randomized, controlled, clinical study of laparoscopic vs open tension-free inguinal hernia repair

BACKGROUND: The aim of this prospective, randomized, controlled clinical study was to compare laparoscopic transabdominal preperitoneal (TAPP) hernia repair with a standard tension-free open mesh repair (open). METHODS: A total of 108 low-risk patients with unilateral (primary or recurrent) or bilateral hernias were randomized to TAPP (group 1 = 52 cases) or open (group 2 = 56 cases). The outcome measures included operating time, complications, postoperative pain, return to normal activity, operating theater costs, and recurrences. RESULTS: The mean operative time was longer for the TAPP than for the open group only in unilateral primary hernias. At rest, the median Visual Analog Scale (VAS) score was higher for group 1 than group 2 at 48 h postoperatively. Mild to discomforting pain in the inguinal region after 7 days, night pain after 30 days, and inguinal hardening after 3 months were more frequent in group 2 than group 1. No significant differences were observed in return to normal activities between the groups. One hernia recurrence was observed after 1 month in group 1. TAPP was significantly more expensive than open. CONCLUSIONS: TAPP was associated with less postoperative pain than open. The increase in operating theater costs, however, was dramatic and was not compensated by shorter time away from work. TAPP should not be adopted routinely unless its costs can be drastically reduced.     

Laparoscopic treatment of gallbladder and common bile duct stones: a prospective study

The aim of this study was to investigate prospectively the feasibility, success rate, safety, and short-term results of single-stage laparoscopic treatment of gallstones and ductal stones in 100 consecutive, unselected patients. Common bile duct (CBD) stones were diagnoses at routine intraoperative cholangiography and choledochoscopy in 100 of 950 patients with gallstones undergoing laparoscopic cholecystectomy (LC). Unsuspected CBD stones were present in 39 patients (4.1% of 950; 39% of 100); 26 patients were referred for surgery after failed endoscopic sphinctertomy (ES) performed elsewhere. Transcystic duct CBD exploration (TC-CBDE) was the procedure of choice. When it was not feasible, choledochotomy and direct CBD exploration (D-CBDE) was performed. Use of biliary drainage was liberal. A completion cholangiogram was obtained for all patients. Laparoscopic treatment of CBD stones was successful in 96 patients: after TC-CBDE in 63 and after D-CBDE in 33. Four operations were converted to open surgery (4%). Retained stones, observed in five patients, were treated by ES in two cases and by percutaneous endoscopic/fluoroscopic lithotripsy in three. Minor morbidity included biloma (n = 2), port site infection (n = 2), and subumbilical hematoma (n = 1). Major morbidity was bile leakage from the cystic duct stump in two cases due to clips or transcystic duct drainage displacement, respectively. One elderly, high risk patient died after being referred for several failed attempts of endoscopic clearance; she died from cardiogenic shock 3 days after successful laparoscopic treatment. Laparoscopic CBD exploration is feasible and safe in most patients, with short-term results that compare favorably with the results of sequential ES/LC reported in the literature.     

Impact of double Rayleigh scattering noise in distributed higher order Raman pumping schemes

We analyze the equivalent optical noise figure (NF) performances and double Rayleigh-scattering-induced noise characteristics of distributed Raman amplifiers based on higher order pumping schemes. We confirm that higher order counterpumping configurations improve the amplifier equivalent NF but also increase multipath interference noise, inducing system penalties at high ON-OFF Raman gain. A Q-factor analysis allows a quantitative evaluation of the real benefits provided by higher order pumping schemes.     

Load balancing to adjust for proximity in some network topologies

Each job scheduler in large decentralized load balancing systems generally must consider whether it is advantageous to offload jobs to remote computation servers when the local load is too high. Although processing power may appear to be available at a very distant server, two problems arise due to the transmission delay between the scheduler and server. Predictably, the response time of the job is adversely affected as the job spends valuable time in transit, but a more subtle problem involves the value, or reliability, of the state information regarding job queues. The longer the delay between scheduler and server, the less a scheduler should value the state information of the server (given that the state changes over time). We examine the performance of schedulers in topologies with different average proximity and show a probabilistic algorithm that allows schedulers to dynamically form efficient clusters in the network.     

Outcome of blunt thoracic aortic injury in a level I trauma center: an 8-year review

BACKGROUND: The purpose of this study was to evaluate our experience with blunt thoracic aortic injury and identify factors predictive of outcome. METHODS: Hospital charts, trauma registry data, and autopsies of 64 patients with blunt thoracic aortic injury from 1988 to 1995 were reviewed. RESULTS: Patients were identified and segregated based on admission physiology. Group 1 patients (n = 19) arrived in arrest. Group 2 patients (n = 10) arrived in shock with systolic BP 90. Group 3 patients (n = 35) arrived with systolic BP>90. All patients in groups 1 and 2 expired. Injury Severity Scores for nonsurvivors in group 3 (n = 12) were significantly higher than survivors. There were no significant differences when comparing time of injury to repair or arrival between groups, or in mortality or paralysis comparing repair techniques or clamp/bypass times. Double lumen endotracheal tubes caused significant operative delays compared to single lumen tubes. CONCLUSIONS: Predictors of survivability were hemodynamic stability on arrival and lower Injury Severity Scores. In thoracic aortic injury patients arriving hemodynamically stable, Injury Severity Score correlated with mortality but not paralysis.     

Synthesis of photoaffinity label analogues of alpha-tocopherol

Photoaffinity analogues of alpha-tocopherol have been synthesized that incorporate the photosensitive 4-azido-2,3,5,6-tetrafluorobenzyloxy group at the terminus of unbranched analogues of the naturally occurring phytyl side chain. An intermediate from these syntheses has also been used to generate a supported ligand for bioaffinity chromatography of alpha-tocopherol binding proteins.     

Hydrocortisone inhibits granulocyte-macrophage colony-stimulating factor production from normal human peripheral blood mononuclear cells and CD3+ T cells

Normal human peripheral blood mononuclear cells (MNCs), particularly T lymphocytes (T cells), are a rich source of granulocyte-macrophage colony-stimulating factor (GM-CSF). Glucocorticoids are known to inhibit GM-CSF production in in vitro cultures of a human fibroblast cell line and in normal human blood monocytes and alveolar macrophages. To determine whether glucocorticoids also inhibit GM-CSF production from normal human MNCs and T cells, we set up cultures of normal human MNCs and T cells in a liquid system in the presence and absence of 5, 50, and 250 microg/dL of hydrocortisone, and an hour later, a constant dose of 50-ng/mL Escherichia coli lipopolysaccharide (LPS) or 10-microg/mL phytohemagglutinin (PHA) was added. After three days, cell counts and GM-CSF levels were determined. Administering 50- and 250-microg/dL hydrocortisone decreased lymphocyte recovery from MNC cultures with LPS (p < or = 0.01), and 250 microg/dL of hydrocortisone decreased lymphocyte recovery from MNC and T-cell cultures with PHA (p < or = 0.03). The amount of GM-CSF produced from PHA-stimulated MNCs was about 100-fold higher than that produced from LPS-stimulated MNCs. The magnitude of GM-CSFs produced in MNC and T-cell cultures stimulated by PHA was comparable (p=0.88). Administering hydrocortisone at 5, 50, and 250 pg/dL decreased GM-CSF production (p < 0.003) in LPS- or PHA-stimulated MNC cultures and in PHA-stimulated T-cell cultures. PHA (not tested with LPS)-stimulated GM-CSF messenger RNA (mRNA) expression was blocked by hydrocortisone. These results indicate that lower concentrations of hydrocortisone inhibit GM-CSF production from normal human blood MNCs and T cells entirely by inhibiting the expression of GM-CSF mRNA, and higher concentrations of hydrocortisone inhibit by a combined effect of inhibiting the expression of GM-CSF mRNA and decreasing the lymphocyte count.