Coherent lidar airborne wind sensor II: flight-test results at 2 and 10 νm

The use of airborne laser radar (lidar) to measure wind velocities and to detect turbulence in front of an aircraft in real time can significantly increase fuel efficiency, flight safety, and terminal area capacity. We describe the flight-test results for two coherent lidar airborne shear sensor (CLASS) systems and discuss their agreement with our theoretical simulations. The 10.6-μm CO(2) system (CLASS-10) is a flying brassboard; the 2.02-μm Tm:YAG solid-state system (CLASS-2) is configured in a rugged, light-weight, high-performance package. Both lidars have shown a wind measurement accuracy of better than 1 m/s.     

Application of genetic markers to the identification of recrudescent Plasmodium falciparum infections on the northwestern border of Thailand

PATIENTS AND METHODS: The role of cerebral magnetic resonance imaging (MRI) in the diagnosis of growth hormone (GH) deficiency in children has been studied in 100 children. The diagnosis of GH deficiency was assessed at a mean age of 6.7 +/- 4.1 years: morphological abnormalities of the hypothalamic-pituitary (HP) region have been studied in three different groups: in the first group (70 cases), the neurohypophysis was present and normally located; in the second group (ten cases) it was missing; in the third group (20 cases) the neurohypophysis was ectopic (truncated stalk syndrome with ectopic neurohypophysis, small antehypophysis, thin or non-visualized stalk). RESULTS: In the majority of cases, children presenting with only one morphological abnormality of the HP region (ectopic neurohypophysis or small antehypophysis or non-visualized or thin stalk) had an isolated GH deficiency. When multiple morphological abnormalities were present, anterior pituitary deficiency was multiple in more than half the cases. Cerebral midline anomalies (above all Chiari I malformation and basipharyngeal canal) had been observed in 20% of the children presenting with GH deficiency. In the majority of cases (95%), these anomalies were associated with one or more abnormalities of the HP region. A familial case is reported: morphological anomalies of the HP region were different for both siblings. Genetic factors are evoked. CONCLUSION: The severity of the hormone deficiency is correlated to the ectopic location of the neurohypophysis, the thin appearance or non visibility of the pituitary stalk and the associated midline anomalies.     

Total simultaneous repair of coarctation and intracardiac pathology in adult patients

OBJECTIVE: To determine whether neutralizing antibodies (NABs) to interferon beta (IFNbeta)-1a (Avonex) and IFNbeta-1b (Betaseron) cross-react. BACKGROUND: A total of 38% of MS patients treated with IFNbeta-1b and 22% of those treated with IFNbeta-1a were reported to develop NABs, which could reduce the clinical efficacy of the drug. METHODS: Blood from 10 MS patients was collected before and at 3 and 6 months after initiating treatment with IFNbeta-1a. ELISA was performed to detect binding antibodies to IFNbeta-1a. Sera from patients who tested positive for binding antibodies to IFNbeta-1a were then screened for NABs to IFNbeta-1a in a biologic assay based on neutralization of antiviral activity. These serum samples were subsequently tested for cross-reactivity with IFNbeta-1b both in the ELISA and the biologic assay. In the second part of the study, sera from patients who participated in the phase III IFNbeta-1b trial at the University of Maryland were examined for cross-reactivity with IFNbeta-1a in the ELISA and the biologic assay. RESULTS: Of the 10 patients treated with IFNbeta-1a, three developed binding as well as NABs to IFNbeta-1a 6 months after treatment, and these antibodies cross-reacted with IFNbeta-1b both in the binding and the biologic assay. Similarly, sera from six patients with NABs to IFNbeta-1b showed cross-reactivity with IFNbeta-1a in the binding assay. Three of these six serum samples tested for neutralizing activity against IFNbeta-1a demonstrated the presence of NABs to IFNbeta-1a. CONCLUSIONS: NABs to IFNbeta-1a (Avonex) and IFNbeta-1b (Betaseron) cross-react, both in the binding and the biologic assays. This suggests that switching to alternate IFNbeta preparation in patients who develop NABs may not be clinically beneficial. Studies examining cross-reactivity between NABs to IFNbeta-1a and IFNbeta-1b in a large number of patients are indicated.     

Retrospective analysis of 19 cases of isolated torsion of the splenic pedicle in dogs

Nineteen cases of isolated splenic torsion in the dog were reviewed retrospectively. Perioperative data were analysed in order to determine prognostic indicators of morbidity and mortality for animals with this disease. This Great Dane and German shepherd dog were found to be at increased risk for this condition. The historical features of splenic torsion were non-specific and included intermittent signs of gastrointestinal disease and abdominal discomfort. Mean duration of malaise was eight days, but 17 dogs were presented because of a rapid deterioration in their condition. Abdominal ultrasound findings assisted in the decision to perform surgery in all the dogs on which it was performed. Eighteen animals had splenic torsion confirmed at surgery and were treated by total splenectomy. All 18 surgically managed dogs survived. Analysis of pre- and postoperative data failed to reveal preoperative parameters that consistently predicted postoperative complications.     

Diagnosis and management of traumatic aorto-right ventricular fistulas

BACKGROUND: Traumatic aorto-right ventricular (Ao-RV) fistulas are rare lesions that result in congestive heart failure if left untreated. Early diagnosis and prompt surgical intervention are required to avoid the natural outcome of cardiac decompensation. METHODS: All cases of traumatic Ao-RV fistula described in the English literature since 1958 were reviewed. The clinical presentation, methods of diagnosis, and treatment strategies were assessed to determine the pathophysiology, natural history, and outcome of surgical intervention. RESULTS: Forty cases of traumatic Ao-RV fistulas were described in the English literature. There were 39 men and 1 woman, with a mean age of 28.3 years (range, 15 to 50 years). Twenty-two (55%) patients had isolated Ao-RV fistulas. Fourteen (35%) had Ao-RV fistulas with aortic insufficiency. Definitive surgical repair was performed in 38 patients. The associated aortic valve injuries were managed with repair techniques or replacement with prosthetic devices. The surgical outcomes in all patients were satisfactory. CONCLUSIONS: The pathophysiology and natural history of Ao-RV fistulas involves the development of congestive heart failure. Traumatic aortic insufficiency frequently is associated with this disorder. Early diagnosis and prompt treatment are necessary to avoid the natural outcome of cardiac decompensation. Definitive repair should be performed with the aid of cardiopulmonary bypass during the same hospitalization.     

Direct observation of single flexible polymers using single stranded DNA()

Over the last 15 years, double stranded DNA (dsDNA) has been used as a model polymeric system for nearly all single polymer dynamics studies. However, dsDNA is a semiflexible polymer with markedly different molecular properties compared to flexible chains, including synthetic organic polymers. In this work, we report a new system for single polymer studies of flexible chains based on single stranded DNA (ssDNA). We developed a method to synthesize ssDNA for fluorescence microscopy based on rolling circle replication, which generates long strands (>65 kb) of ssDNA containing "designer" sequences, thereby preventing intramolecular base pair interactions. Polymers are synthesized to contain amine-modified bases randomly distributed along the backbone, which enables uniform labelling of polymer chains with a fluorescent dye to facilitate fluorescence microscopy and imaging. Using this approach, we synthesized ssDNA chains with long contour lengths (>30 μm) and relatively low dye loading ratios (~1 dye per 100 bases). In addition, we used epifluorescence microscopy to image single ssDNA polymer molecules stretching in flow in a microfluidic device. Overall, we anticipate that ssDNA will serve as a useful model system to probe the dynamics of polymeric materials at the molecular level.     

Three-dimensional analysis of the interaction between a matrix crack and nanofiber

A three-dimensional study of interactions between a matrix crack and nanofibers is undertaken. The nanofibers considered in the study have a hollow structure and a certain wall thickness. The analytical study is performed by considering a penny-shaped crack propagating towards a pair of nanofibers placed symmetrically with respect to the crack. The three-dimensional study accounts for the influence of nanofiber hollow geometry and outer diameter on crack energetics. The effect of the mismatch between the elastic properties of nanofiber and matrix is also considered. Finally, the influence of the interphase between nanofiber and matrix on crack energetics is investigated. Energy release rates along the crack front of the penny-shaped crack are computed to understand the nature of the toughening effect of nanofibers. The results of the study indicate a significant influence of nanofiber wall thickness and longitudinal modulus on crack energetics. Also, the presence of an interphase between a nanofiber and matrix seems to alter the crack energetics considerably. Finally, the results of the study indicate that nanofiber diameter may have a positive or negative effect on resistance to crack propagation depending on nanofiber wall thickness.     

Lipid-lipid complexes: Properties and effects on lipase binding to surfaces

In the presence of bulk water, the lipase-catalyzed synthesis and hydrolysis of insoluble lipid esters occur at the lipid-water interface. For water-soluble lipases, a necessary step in this process is the partitioning of enzyme from the bulk aqueous phase to the surface phase. In surface phases of phospholipids and the substrates and products of lipolysis, physical studies have demonstrated the formation of preferred packing arrays or lipid-lipid “complexes.” Such interactions involve changes in both lipid molecular area and hydration. Binding of pancreatic carboxylester lipase (cholesterol esterase) and colipase to monomolecular films of a phosphatidylcholine and its complexes with fatty acid or diglyceride is negligible. In contrast, saturation of film of pure fatty acid or diglyceride correlates with formation of a protein monolayer. With mixtures of complex and uncomplexed fatty acid or diglyceride, binding to the uncomplexed lipid occurs, but only with colipase can saturation of available sites be achieved. The lower affinity of carboxylester lipase for surfaces containing complexes can be qualitatively explained by differences in the size of lipid and protein molecules. Because it involves no direct interaction between enzyme and complex, such “proxinhibition” of enzyme binding is potentially an important regulation of lipid-protein interactions. Presented at the symposium “The Biology, Biochemistry and Technology of Lipases” at the 78th annual meeting of the American Oil Chemists’ Society held May 17–21, 1987, in New Orleans, Louisiana.