Determination of reference values for optical properties of liquid phantoms based on Intralipid and India ink.

A multi-center study has been set up to accurately characterize the optical properties of diffusive liquid phantoms based on Intralipid and India ink at near-infrared (NIR) wavelengths. Nine research laboratories from six countries adopting different measurement techniques, instrumental set-ups, and data analysis methods determined at their best the optical properties and relative uncertainties of diffusive dilutions prepared with common samples of the two compounds. By exploiting a suitable statistical model, comprehensive reference values at three NIR wavelengths for the intrinsic absorption coefficient of India ink and the intrinsic reduced scattering coefficient of Intralipid-20% were determined with an uncertainty of about 2% or better, depending on the wavelength considered, and 1%, respectively. Even if in this study we focused on particular batches of India ink and Intralipid, the reference values determined here represent a solid and useful starting point for preparing diffusive liquid phantoms with accurately defined optical properties. Furthermore, due to the ready availability, low cost, long-term stability and batch-to-batch reproducibility of these compounds, they provide a unique fundamental tool for the calibration and performance assessment of diffuse optical spectroscopy instrumentation intended to be used in laboratory or clinical environment. Finally, the collaborative work presented here demonstrates that the accuracy level attained in this work for optical properties of diffusive phantoms is reliable.

Gunshot induced indirect femoral fracture: mechanism of injury and fracture morphology.

INTRODUCTION: Indirect ballistic fractures occur when a projectile passes close to, but not contacting, the bone. The mechanism of how these fractures occur is not yet proven, but recently the acoustic shockwave has been excluded as a cause. The objective of this study is to determine whether the expanding temporary cavity, the collapse of this cavity or its oscillation causes these fractures. In addition, we describe the fracture morphology and biomechanical causes of this injury. METHOD: 40 fresh deer femora were strain gauged and embedded in ballistic gelatin before being shot with four different projectiles with varying distances off the bone. Pressure recordings, chronographs and radar allowed assessment of local pressures and energy transfer. High-speed video allowed the temporal relationship between the temporary cavity and fracture formation to be analysed, while sample dissection allowed the fracture morphology to be described. RESULTS: The fractures produced were consistently wedge-shaped and caused by the expansion of the temporary cavity, flexing the bone beyond its yield point, causing tension failure on the cortex opposite the expanding temporary cavity and a compression wedge on the side of the cavity. Local pressure was not predictive of fracture formation but the energy transfer to the gelatin block was predictive. CONCLUSIONS: Indirect fractures are caused by the expansion of the temporary cavity and relate to the proximity of this cavity to the bone. Fractures occur from flexion of the bone and classically display wedge-shaped fracture patterns with the apex of the wedge pointing away from the expanding cavity.

Identifying the source of bullet wipe: a randomised blind trial.

OBJECTIVE: To assess the usefulness of scanning electron microscopy and energy dispersive x-ray spectroscopy in matching bullet wipe to the bullet. HYPOTHESIS: Bullet wipe can be used to match a bullet type to a crime scene.

The use of magnetic field effects on photosensitizer luminescence as a novel probe for optical monitoring of oxygen in photodynamic therapy.

The effect of a magnetic field on the steady-state and time-resolved optical emission of a custom fullerene-linked photosensitizer (PS) in liposome cell phantoms was studied at various oxygen concentrations (0.19-190 microM). Zeeman splitting of the triplet state and hyperfine coupling, which control intersystem crossing between singlet and triplet states, are altered in the presence of low magnetic fields (B < 320 mT), perturbing the luminescence intensity and lifetime as compared to the triplet state at B = 0. Measurements of the luminescence intensity and lifetime were performed using a time-domain apparatus integrated with a magnet. We propose that by probing magnet-affected optical emissions, one can monitor the state of oxygenation throughout the course of photodynamic therapy. Since the magnetic field effect (MFE) operates primarily by affecting the radical ion pairs related to type I photodynamic action, the enhancement or suppression of the MFE can be used as a measure of the dynamic equilibrium between the type I and II photodynamic pathways. The unique photo-initiated charge-transfer properties of the PS used in this study allow it to serve as both cytotoxic agent and oxygen probe that can provide in situ dosimetric information at close to real time.

A net with complex weights.

In this article a new neural-network architecture suitable for learning and generalization is discussed and developed. Although similar to the radial basis function (RBF) net, our computational model called the net with complex weights (CWN) has demonstrated a considerable gain in performance and efficiency in number of applications compared to RBF net. Its better performance in classification tasks is explained by the cross-product terms in internal representation of its basis function introduced parsimoniously. Implementation of CWN by the ensemble approach is described. A number of examples, solved using CWN and other networks, are used to illustrate the desirable characteristics of CWN.

The ensemble approach to neural-network learning and generalization.

In this paper a new method is suggested for learning and generalization with a general one-hidden layer feedforward neural network. This scheme encompasses the use of a linear combination of heterogeneous nodes having randomly prescribed parameter values. The learning of the parameters is realized through adaptive stochastic optimization using a generalization data set. The learning of the linear coefficients in the linear combination of nodes is achieved with a linear regression method using data from the training set. One node is learned at a time. The method allows for choosing the proper number of net nodes, and is computationally efficient. The method was tested on mathematical examples and real problems from materials science and technology.

Meiotic behaviour of the minichromosome in the phytopathogenic ascomycete Leptosphaeria maculans.

All Leptosphaeria maculans field isolates displayed a minichromosome (MC) clearly separated from the overall electrokaryotype following pulsed-field gel electrophoresis. MCs exhibited a length polymorphism ranging from 650 to 950 kb. Tetrad analyses revealed the parental inheritance of MC length polymorphism (50% of the tetrads) or else the generation of novel-sized MCs (27%), which suggested that recombination occurred between MCs. Nineteen percent of the tetrads displayed a lack of the MC band in the electrokaryotype for one or two of the four resulting genotypes. Crosses between isolates carrying or lacking MCs revealed non-Mendelian segregation and suggested that some isolates could display at least two copies of the MC. Only repeated sequences hybridising to all chromosomes were isolated from the MC. Finally, saprophytic or parasitic fitness was not modified when isolates apparently lacked the MC. All these data suggested that the L. maculans MC behaves like a 'B' chromosome.

Neural-net computing for interpretation of semiconductor film optical ellipsometry parameters.

Optical ellipsometry has been found to be a promising technique for monitoring process parameters, such as film composition and film thickness, of semiconductor wafers grown with molecular beam epitaxy. Whereas it is a straightforward task to calculate ellipsometry angles given the thickness of the film and the refractive indexes of the film and substrate, it is a difficult task to invert that mathematical relationship. However, the process must be inverted if the measured parameters are to be interpreted meaningfully in terms of film composition and film thickness. This paper reports on the use of neural-net computing for the inverse mapping of measured ellipsometry parameters. We used a functional-link net which is very efficient in function approximation. The advantage of using the net, however, is not only its speed, but also because some other net architecture characteristics allow us to perform the task in a holistic manner.

Industrial rehabilitation comes of age.

Yes, industrial rehabilitation has come of age. The "trendiness" and "glitz" associated with such programs are now gone (or, at least, on the wane). These programs are now being subjected to the same scrutiny as other business ventures, no longer seen as the "cash cows" that single-handedly can end the financial woes of an organization. Along with this maturity has come an accreditation system with accepted standards of practice, care and methodological style; a data base reporting on the range and limits of program capability; and the realization by the insurance community that industrial rehabilitation can be effective and that these programs are reasonable assessment and intervention alternatives for selected patients. We have also noted that as these programs grow past their adolescence it will be important to pay close attention to basic questions of cost, value, and worth. While most programs have not been totally "institutionalized" into the health care provision system, their honeymoon phase has reached a positive conclusion. It's now time to look very closely at where we are today, remember where we have come from, and look to the future with a realistic and clear view.

Documentation and evaluation of fevers in hospital-based and community-based nursing homes.

We reviewed clinical evaluation practices and documentation of fever (greater than or equal to 100.2 degrees F) in all febrile patients over a two-month period in a hospital-based nursing home (HBNH) compared with a community-based nursing home (CBNH). Results showed 38 febrile (mean 101.9 degrees F) HBNH patients and 26 febrile (mean 101.5 degrees F) CBNH patients. Median time from fever onset to physician contact was 4 hours in HBNH and 12.5 hours in CBNH episodes (P less than 0.01). Laboratory studies were initially performed in 68% of HBNH and 31% of CBNH episodes (P less than 0.005), and diagnosis of fever source was documented in 76% of HBNH and 16% of CBNH episodes (P less than 0.005). Overall assessment stratification showed 81% febrile HBNH patients had both evaluation and therapy performed compared with 38% in CBNH (P less than 0.0001); 39% of febrile CBNH patients had no evaluation or therapy performed. Results indicate lack of documentation, and fever evaluation in CBNHs may preclude complete detection of nursing home-acquired infections and thereby hamper preventive responses to potential infection problems.

Survey of nursing personnel attitudes toward infections and their control in the elderly.

To better understand nursing practice in geriatric care settings as it relates to infections, a survey of nursing attitudes about a variety of infection control issues was undertaken. Nurses were recruited from four settings: a university-affiliated, private nursing home (N = 46), a hospital-based nursing home (N = 33), a private nursing home (N = 20), and a home care agency (N = 26). The nurses appropriately recognized the importance of pneumonia and influenza as major threats to health in these settings and also reported some indifference regarding the notification of physicians about fevers under 38.9 degrees C (102.0 degrees F). Among the groups, similar attitudes about infection control principles were recorded, except that the ratings by the home care agency nurses were different from those of the institution-based nurses in the following areas: isolation as a means to prevent infection spread, proper waste disposal methods, and frequency of catheter change. Assessment of personnel attitudes and practices are important in detecting problems, guiding in-service programing, and revising care practices.

Comparison of methods for calculation and depiction of incidence infection rates in long-term care facilities.

Assessment of changes in endemic infections in health care facilities are often based on comparison of infection rates over time. This study compared two methods for calculating and depicting infection data at a hospital-based nursing home care unit. Prospective incidence surveillance of nursing home acquired infections was conducted over a 12-month period, during which time denominator information on census and patient care days was also collected. Monthly infection rates were calculated based on (a) census (number infections per month/average monthly census), and (b) care duration (number infections per month/average monthly resident stay days). Results showed average monthly infection incidence of 27.4 episodes, (range 19-37), with average monthly census of 166.2 (range 160.0-180.0) and average monthly patient days of 5056 (range 4631-5583). The average census based monthly infection rate was 16.5 (range 11.9-22.4); average care duration based monthly infection rate was 5.4 (range 3.8-7.2) episodes per 1000 patient care days. Results indicate care duration based rates demonstrate less marked rate fluctuation than census based findings, and that duration based rates are more similar to values observed in acute care hospital nosocomial infection rates, thus are less likely to be misunderstood or misinterpreted by staff. Institutions should consider analyzing their methods for depicting infection data to provide consistency and clarity in data reporting.

Cognitive characteristics of bulimic and drug-abusing women.

This descriptive study contrasted specific coping styles, attitudes, and irrational beliefs among three groups of women: bulimics, drug abusers, and a normative comparison group. The substance abuse groups were found to be more irrational than the comparison group and were moodier and more socially alienated. They also were prone to a negative view of the world and a bleak outlook toward the future. Bulimic subjects put considerable importance on others' approval, tended to denigrate themselves, and were under a lot of self imposed pressure and chronic tension; drug abuse subjects were more introversive, perfectionistic, and subject to recent stress. By contrast, the normative comparison group appeared confident, sociable, and optimistic.