Ordered nanostructures written directly by laser interference.

We present a simplified method to employ laser interference lithography for the fabrication of ordered nanostructures. Neither resist, nor an elaborate fabrication process was needed. Four-beam interference patterns generated in this work included periodic arrays of holes in GaAs, covered with SiO(2) bubbles, and they were directly written into the sample. The diameters of the smallest holes were less than 30 nm. We propose a model to interpret the results.

Double clad tapered fiber for high power applications.

We report a novel type of active fiber - tapered double clad fiber suitable for pumping by low brightness sources with large beam parameter product of 50/300 mm x mrad. Ytterbium double clad all-silica fiber (core/1(st) clad/2(nd) clad diameters 27/834/890 mum, NA(core)=0.11, NA(clad)=0.21), tapered down by a factor 4.8 for a length of 10.5 m was drawn from a preform fabricated by plasma chemical technologies. At a moderate Yb-ion concentration and 1:31 core/cladding ratio, the tapered double clad fiber demonstrates 0.9 dB/m pump absorption at 976 nm and excellent lasing slope efficiency. An ytterbium fiber laser with 84 W of output power and 92% slope efficiency, a 74 W superfluorescent source with 85% slope efficiency and amplifiers operating both in CW and pulsed regimes have been realized. All devices demonstrated robust single mode operation with a beam quality factor of M(2)=1.07.

Necrotizing soft-tissue infections caused by marine vibrios.

Halophilic, noncholera marine Vibrio bacteria can cause septicemia, gastroenteritis, cellulitis, and necrotizing fasciitis. We describe six patients with necrotizing fasciitis and review 12 cases described previously. The 18 patients included 14 men and four women. Their ages ranged from 32 to 79 years (average 58.1 years). Eleven patients were older than 55 years. Nine infections were caused by V. vulnificus, three by V. parahaemolyticus, and one by V. alginolyticus. In five cases the Vibrio species was not identified. Twelve patients had associated conditions that might have made them more susceptible to these infections, such as cirrhosis, steroid therapy, hemochromatosis, and multiple myeloma. These infections usually occur in apparently insignificant wounds (puncture wounds, insect bites) exposed to sea water or fish. Treatment is by debridement and antibiotic therapy. Three patients required amputation to control the infection. Six (33.3%) of the 18 patients died.

Surgical management of the failed jejunoileal bypass.

The jejunoileal bypass is an efficient surgical treatment for morbid obesity, but it has a high complication rate that necessitates reversal in about 25 percent of patients. Conversion to Roux-Y gastric bypass was associated with acceptable morbidity and provided excellent control of weight. On the other hand, conversion to gastric partition resulted in weight gain almost equal to that seen with simple reversal alone. Conversion to Roux-Y gastric bypass is an acceptable procedure in the surgical treatment of the unsuccessful jejunoileal bypass.

Management of massive hemorrhage associated with abdominal trauma.

Control of massive hemorrhage from intra-abdominal organs and major vascular structures may tax the ingenuity of the trauma surgeon. It is emphasized, however, that total blood loss and the amount of transfused blood are far less critical than the duration and severity of shock.

Nutritional support by intraperitoneal dialysis in the rat: maintenance of body weight with normal liver and plasma chemistries.

A rat model was developed to study intraperitoneal (ip) dialysis as a means of total nutritional support. Rats (200 g) were implanted ip with a catheter device and connected to a rodent infusion assembly. An automated system exchanged 10-ml volumes of a 37 degrees C solution containing 10% dextrose, 2% amino acid solution plus micronutrients. Rats were adapted over 3 days to a schedule of 16 1-hr cycles/day, and continued on this regimen for another 4 days. Rats subjected to this program maintained similar body weight, nitrogen balance, plasma chemistries, and liver tests in comparison to control animals fed per os in isocaloric and isonitrogenous amounts. Efficiency of peritoneal absorption for both glucose and amino acid was 95%. Histological examination of intraabdominal organs revealed only mild inflammation. This model is applicable to studies involving nutritional support via the peritoneal cavity, a technique which may be of value in patients with sensitive fluid balances (cardiac, renal, or pulmonary failure).

Anomalous bismuth-stabilized (2x1) reconstructions on GaAs(100) and InP(100) surfaces.

First-principles phase diagrams of bismuth-stabilized GaAs- and InP(100) surfaces demonstrate for the first time the presence of anomalous (2x1) reconstructions, which disobey the common electron counting principle. Combining these theoretical results with our scanning-tunneling-microscopy and photoemission measurements, we identify novel (2x1) surface structures, which are composed of symmetric Bi-Bi and asymmetric mixed Bi-As and Bi-P dimers, and find that they are stabilized by stress relief and pseudogap formation.

Complications of Hickman-Broviac catheters.

Although Hickman-Broviac catheters have improved the care of patients with leukemia and patients using catheters for hyperalimentation, they are associated with a substantial morbidity. We experienced a 34 per cent complication rate. Some of these complications may be relieved with new therapy (streptokinase) and some of the intraoperative problems can be prevented by a more careful technique. We believe the cephalic vein cutdown technique remains the procedure of choice. Due to the morbidity of placement, every attempt should be made to save a catheter, as in type 1 infections. Type 2 infections should be the major indication for removal of the catheters.

Necrotizing fasciitis.

Necrotizing infections of soft tissues are rapidly progressive infections accompanied by a high mortality. Clinical presentation involves fever, cellulitis, edema, crepitus, bullae, necrosis and sepsis. Operative findings include fascial and subcutaneous tissue necrosis with or without myonecrosis. The treatment is prompt surgical debridement. Delay in treatment results in decreased survival time. The mortality in our study was 30 per cent (20 of 33). The time from recognition of an infection by the patient or physician until operative debridement averaged three and one-half days for survivors compared with 11.7 days for nonsurvivors. These infections frequently occur in compromised hosts and the mortality is greatly increased in these patients. Patients with diabetes had a mortality of 63 per cent (five of eight). The mortality for infections of the abdomen (44 per cent) and perineum (38 per cent) is greater than for the extremities (18 per cent). The bacteriologic findings of these infections involved three combinations of organisms. We had 30 mixed infections involving two or more organisms. In addition, three patients had identical signs and symptoms caused by infection with a single organism--Vibrio species. These patients all had some type of contact with a marine environment as a predisposing cause. We also applied both the APACHE and SIS systems to these patients to evaluate the severity of the illness. Nonsurvivors presented with a mean SIS score of 8.64 compared with survivors with 3.82. Initial scores with the APACHE system for nonsurvivors was 12.0 compared with 2.14 for survivors. In both systems, scores rapidly increased at three and seven days in nonsurvivors as compared with a rapid decline in the survivors. We suggest that the best descriptive system is to simply identify the organisms and tissues involved.

Growth factors and determinants of wound repair.

The application of contemporary biochemical, analytical, and production technology have, in part, clarified the physiologic processes and identified many new factors active in wound repair. A restructuring of the sequence of the reparative events for the wound environment followed the identification of an array of hormonal polypeptides and growth factors. Deterrents of the early phases of repair include neoplasms and therapeutic doses of steroidal and cytotoxic agents. The physiological effects of these agents are rapidly reversed following their removal with a resultant enhancement of wound tear strength and wound energy. The use of synthetic growth hormone and recombinant DNA-produced polypeptide may reverse the deleterious wound healing events initiated in the injured and tumor-bearing host.

The treatment of acute cholangitis. Percutaneous transhepatic biliary drainage before definitive therapy.

Forty-two patients with acute cholangitis, as evidenced by fever (95%), jaundice (86%), and right upper quadrant pain (67%), were treated with fluid and electrolyte resuscitation, broad spectrum antibiotic coverage, and initial percutaneous transhepatic biliary drainage (PTD). Despite a 17% incidence of nondilated ductal systems, drainage was established in all patients using a 22-gauge "skinny" needle and "accordion" catheter. No attempt was made at definitive cholangiogram; only 1-2 mL of contrast were injected to confirm placement of the catheter. Sepsis began to resolve in all patients within 24 hours of PTD, after which definitive cholangiogram was performed. PTD was accompanied by a 7% (3/42) complication rate, none of which contributed to subsequent morbidity and mortality. Two patients in severe septic shock had PTD but died within 8 hours of admission, constituting a 5% mortality rate. Definitive therapy after resolution of sepsis included: surgical (16 patients), internal/external drainage (14 patients), balloon dilatation (10 patients), mono-octanoin infusion (1 patient), and ampullary dilatation (1 patient). The surgical morbidity rate was 18%. There was no mortality. PTD is effective in providing decompression as initial therapy for acute cholangitis with minimal morbidity. Accurate diagnosis provided by the definitive cholangiogram obviates the need for multiple surgical procedures. PTD provides a portal to the biliary tract for alternative procedures (i.e., internal/external drainage, balloon dilatation), especially in patients with medical contraindications to surgery.

1.5-microm monolithic GaInNAs semiconductor saturable-absorber mode locking of an erbium fiber laser.

We present a new monolithic GaAs-based semiconductor saturable absorber operating at 1.55 microm. An epitaxially grown absorber mirror in a GaInNAs/GaAs material system was successfully used to mode lock an erbium-doped fiber laser. The GaInNAs material system possesses intriguing physical properties and provides great potential for lasers and nonlinear optical devices operating at the 1.3-1.55-microm wavelength range.

[Hepatic expression of the apolipoprotein B gene in the cow during lactation]. / Expression hépatique du gène d'apolipoprotéine B chez la vache au cours de la lactation.

Variations in apoprotein B hepatic expression were evaluated during lactation in dairy cows. Apoprotein B mRNA levels were significantly decreased in early lactation and this was accompanied by triglyceride accumulation in the liver.

Low-loss 1.3-microm GaInNAs saturable Bragg reflector for high-power picosecond neodymium lasers.

A novel low-loss, single-step-growth 1.3-microm GaInNAs saturable Bragg reflector mode-locking element has been developed. Combined radial thickness and postgrowth annealing control have permitted a tuning range of 46 nm for passive mode locking to be demonstrated from one wafer. With this structure, stabilized mode locking was obtained from quasi-cw diode-pumped Nd:YLF and Nd:YALO lasers operating at 1314 and 1342 nm, respectively, with average on-time output powers of as much as 20 W and pulse durations as low as 22 ps.