Reversal of pretreatment hypotension and control of hemorrhage in trauma patients by a simple device

The injection of a suspension of Walker 256 carcinoma cells into the carotid artery of rats produced a model of hematogenously spread cerebral metastases. Most animals died from massive extracerebral tumors of the head and jaw; brain tumors were present in only one-quarter. External carotid artery ligation prior to tumor inoculation did not increase the incidence of fatal brain tumor. When cyclophosphamide, 15 mg/kg, was injected as a single dose on the fourteenth day after tumor inoculation, most of the extracerebral tumor disappeared. Fifty percent of the animals so treated were cured of tumor, but 90% of the remainder died of large intracerebral tumors. Severe cytopathic changes resulting from cyclophosphamide were present in extracerebral or choroid plexus tumors but were mild or nonexistent in intracerebral tumors. These selective effects of cyclophosphamide suggest that water-soluble agents are less effective against tumor in the brain than against extracerebral tumors despite the fact that metastatic tumor breaks down the blood-brain barrier.     

Self-referencing intensity measurements based on square-wave gated phase-modulation fluorimetry

An adaptation of square-wave gated phase-modulation (GPM) fluorimetry allows for self-referenced intensity measurements without the complexity of dual excitation or dual emission wavelengths. This AC technique utilizes square-wave excitation, gated detection, a reference emitter, and a sensor molecule. The theory and experimental data demonstrating the effectiveness and advantages of the adapted GPM scheme are presented. One component must have an extremely short lifetime relative to the other. Both components are affected identically by changes in intensity of the excitation source, but the sensor intensity also depends on the concentration of the analyte. The fluctuations of the excitation source and any optical transmission changes are eliminated by ratioing the sensor emission to the reference emission. As the concentration of the analyte changes, the corresponding sensor intensity changes can be quantified through several schemes including digitization of the signal and digital integration or AC methods. To measure pH, digital methods are used with Na3[Tb(dpa)3] (dpa = 2,6-pyridinedicarboxylic acid) as the long-lived reference molecule and fluorescein as the short-lived sensor molecule. Measurements from the adapted GPM scheme are directly compared to conventional ratiometric measurements. Good agreement between the data collection methods is demonstrated through the apparent pKa. For the adapted GPM measurements, conventional measurements, and a global fit the apparent pKa values agree within less than 2%. A key element of the adapted GPM method is its insensitivity to fluctuations in the source intensity. For a roughly 8-fold change in the excitation intensity, the signal ratio changes by less than 3%.     

CMOS-compatible optical rib waveguides defined by local oxidation of silicon

The local oxidation of silicon process is shown to be an effective means of defining optical rib waveguides in silicon on insulator while maintaining the surface planarity required for CMOS integration. Experimental waveguides have shown singlemode operation and losses of less than 1 dB/cm in the telecommunications band around 1550 nm     

Operational Analysis of a Quantum Dot Optically Gated Field-Effect Transistor as a Single-Photon Detector

We report on the operation of a novel single-photon detector, where a layer of self-assembled quantum dots (QDs) is used as an optically addressable floating gate in a GaAs/Al_0.2Ga_0.8As delta-doped field-effect transistor. Photogenerated holes charge the QDs, and subsequently, change the amount of current flowing through the channel by screening the internal gate field. The photoconductive gain associated with this process makes the structure extremely sensitive to light of the appropriate wavelength. We investigate the charge storage and resulting persistent photoconductivity by performing time-resolved measurements of the channel current and of the photoluminescence emitted from the QDs under laser illumination. In addition, we characterize the response of the detector, and investigate sources of photogenerated signals by using the Poisson statistics of laser light. The device exhibits time-gated, single-shot, single-photon sensitivity at a temperature of 4 K. It also exhibits a linear response, and detects photons absorbed in its dedicated absorption layer with an internal quantum efficiency (IQE) of up to (68 plusmn18)%. Given the noise of the detection system, the device is shown to operate with an IQE of (53 plusmn 11)% and dark counts of 0.003 counts per shot for a particular discriminator level.     

Process Controls for Individual Section Machines

Improving the productivity of a container manufacturing operation requires reducing the art in the operation of the process and adding process controls. Reducing the art, in turn, requires providing machine control mechanisms that will provide a consistent and repeatable machine operation independent of operator experience. For a glass container line the control mechanisms must provide for a consistent glass flow, a gob distributor synchronized with the gob feeder, a control means for repeatable on-off actuation and velocity control for the mechanical motions on the individual section (IS) machine, and synchronized take-away and stacker conveyors. A system combining these process control functions and providing a catalog of process adjustments by container type is described. This type of control system can provide for a de-skilled glass container manufacturing operation which is repeatable from one run to the next.     

Preferential interactions of fluorescent probe Prodan with cholesterol

The fluorescent probe Prodan has been widely used as a probe of model and biological membranes. Its fluorescent maxima in phospholipid bilayers vary as a function of phase state, with maxima at 485 for the liquid crystal Lalpha, 435 nm for the gel L'beta, and 507 nm for the interdigitated gel LbetaI phase, with excitation at 359 nm. These spectral changes have been used for the detection of phase changes among these phases. In the present study, the fluorescent properties and partition coefficients of Prodan in model membranes of phosphatidylcholines and phosphatidylethanols have been studied as a function of lipid phase state and cholesterol content. It is shown that the Prodan spectrum in the presence of cholesterol no longer reflects the known phase state of the lipid; in each phase state, the presence of cholesterol leads to a spectrum with the maximum at 435 nm, characteristic of the noninterdigitated gel phase. The partition coefficient of Prodan into these lipids also varies with the phase state, giving values of 0.35 x 10(4) in the interdigitated gel, 1.8 x 10(4) in the noninterdigitated gel, and 7. 6 x 10(4) in the liquid crystal phase. In the presence of cholesterol these partition coefficients are increased to 13 x 10(4) for the liquid crystal and the gel phase, and 5.1 x 10(4) in the presence of 100 mg/ml ethanol. These results suggest that Prodan has preferential interactions with cholesterol, and is thus not a randomly distributed fluorescent reporter probe in membranes containing cholesterol. These results suggest that Prodan should be used only with great caution in complex lipid mixtures, particularly biological membranes.     

Surface roughness changes during rolling

The changes in surface topography of a rolled strip have been examined after sequential passes giving various total reductions of cross-sectional area. A relocation technique has been used to reveal details of individual surface hills and valleys, and the data have been digitised for computation of selected surface parameters.It is found that the hills are very easily flattened, but that the valleys persist much longer, even after 40% reduction when a grease lubricant is used. A thin layer of MoS₂ provides lubrication but allows a smooth shiny surface to be produced by rolling.     

Characterisation of a fibre Raman oscillator using fibre grating reflectors

We have constructed a completely integrated fibre Raman oscillator using two fibre grating reflectors. This was synchronously mode-locked using a CW mode-locked Nd:YAG laser operating at 1.06?m. Spectral and temporal characteristics of the Raman oscillator are presented.     

Self‐help housing provision: Production,consumption, accumulation and policy in Atlantic Canada

Self‐help has been a neglected aspect of housing provision in industrialised nations, yet in many locations it accounts for a significant share of new production and can contribute to improved housing circumstances for those whose housing need is not too severe. This paper discusses self‐help housing provision in Atlantic Canada and argues that it reduces the profitability of the residential construction industry and for this and other reasons, self‐help is likely to continue as a major form of production. This paper also evaluates the impact on self‐help of several housing policy options.     

Geomembrane Strain Observed in Large-Scale Testing of Protection Layers

A method for estimating the local strain in a geomembrane due to the indentation of gravel particles is presented. The accuracy of various strain calculation methods is evaluated by a series of tests, and it is shown that the traditional arch elongation method provides only an approximate estimate of the magnitude of strain induced in the geomembrane due to indentation and does not adequately define the distribution of strain. Consideration of the combined membrane and bending strains as proposed here is shown to provide a better representation of the distribution of strains and enhances the evaluation of the peak strains in the geomembrane caused by local indentations. Large-scale tests are conducted using different protection layers, and the strains are reported based on both the arch elongation method and the combined bending and membrane theory. The results indicate that the best protection for the underlying geomembrane was provided by a sand-filled geocushion or a special rubber geomat, which limited strains induced by coarse (40–50 mm) angular gravel to 0.9% at 900 kPa and 1.2% at 600 kPa. The poorest performance was achieved using nonwoven geotextiles with a maximum strain of 8% being obtained with a 435 g∕m2 geotextile at 250 kPa and 13% with two layers of 600 g∕m2 geotextile at 900 kPa.