Probing a century old prediction one plasmonic particle at a time.

In 1908, Gustav Mie solved Maxwell's equations to account for the absorption and scattering of spherical plasmonic particles. Since then much attention has been devoted to the size dependent optical properties of metallic nanoparticles. However, ensemble measurements of colloidal solutions generally only yield the total extinction cross sections of the nanoparticles. Here, we show how Mie's prediction on the size dependence of the surface absorption and scattering can be probed separately for the same gold nanoparticle by using two single particle spectroscopy techniques, (1) dark-field scattering and (2) photothermal imaging, which selectively only measure scattering and absorption, respectively. Combining the optical measurements with correlated scanning electron microscopy furthermore allowed us to measure the size of the spherical gold nanoparticles, which ranged from 43 to 274 nm in diameter. We found that even though the trend predicted by Mie theory is followed well by the experimental data over a large range of nanoparticle diameters, for small size variations changes in scattering and absorption intensities are dominated by factors other than those considered by Mie theory. In particular, spectral shifts of the plasmon resonance due to deviations from a spherical particle shape alone cannot explain the observed variation in absorption and scattering intensities.

Modified RV short axis series--a new method for cardiac MRI measurement of right ventricular volumes.

PURPOSE: The current standard image orientation employed in the MRI assessment of right ventricular volumes uses a series of short axis cine acquisitions located with respect to a horizontal long axis view with the first slice placed across the atrio-ventricular valve plane at end diastole. Inherent inaccuracies are encountered with the use of this image orientation due to difficulty in defining the tricuspid valve and the border between atrium and ventricle on the resultant images. Our experience indicates that because the tricuspid valve is usually not in-plane in the slice the atrio-ventricular margin is difficult to distinguish. This leads to inaccuracies in measurements at the base of the RV and miscalculation of the RV volume. The purpose of this study was to assess an alternative method of image orientation aimed at increasing the accuracy of RV volume measurements using current commercially available CMRI sequences. This technique, the modified RV short axis series, is oriented to the outflow tract of the right ventricle. METHOD: We undertook a prospective study of 50 post cardiac transplant patients. A series of LV short axis multi-slice cine acquisition FIESTA images was acquired using the current standard technique. From this data set, LV and RV stroke volumes were derived on an Advantage Windows workstation using planimetry of the endocardial and epicardial borders in end systole and end diastole. Our new technique involved obtaining a set of multi-slice cine acquisition FIESTA images in a plane perpendicular to a line from the centre of the pulmonary valve to the apex of the RV. Planimetry of the RV was then performed and a stroke volume calculated using the same method of analysis. RV stroke volumes obtained from both techniques were compared with LV stroke volumes. Three operators independently derived RV data sets. RESULTS: On the images acquired with the new technique, the tricuspid valve was easier to define leading to more accurate and reproducible planimetry of ventricular borders. RV stroke volumes calculated from the new method showed better agreement with LV stroke volumes than with the current method. These results were consistent across the three operators. CONCLUSIONS: This new method improves visualisation of the tricuspid valve and makes analysis easier and less prone to operator error than the current standard technique for MRI assessment of RV volumes.

Mechanism of dihydrogen cleavage by high-valent metal oxo compounds: experimental and computational studies.

The oxidation of dihydrogen by metal tetraoxo compounds was investigated. Kinetic measurements of the oxidations of H(2) by MnO(4)(-) and RuO(4), performed by UV-vis spectroscopy, showed these reactions to be quite rapid at 25 degrees C (k(1) approximately (3-6) x 10(-2) M(-1) s(-1)). Rates measured for H(2) oxidation by MnO(4)(-) in aqueous solution (using KMnO(4)) and in chlorobenzene (using (n)Bu(4)NMnO(4)) revealed only a minor solvent effect on the reaction rate. Substantial kinetic isotope effects [(k(H)2/k(D)2 = 3.8(2) (MnO(4)(-), aq), 4.5(5) (MnO(4)(-), C(6)H(5)Cl soln), and 1.8(6) (RuO(4), CCl(4) soln)] indicated that H-H bond cleavage is rate determining and that the mechanism of dihydrogen cleavage is likely similar in aqueous and organic solutions. Third-row transition-metal oxo compounds, such as OsO(4), ReO(4)(-), and MeReO(3), were found to be completely unreactive toward H(2). Experiments were performed to probe for a catalytic hydrogen/deuterium exchange between D(2) and H(2)O as possible evidence of dihydrogen sigma-complex intermediates, but no H/D exchange was observed in the presence of various metal oxo compounds at various pH values. In addition, no inhibition of RuO(4)-catalyzed hydrocarbon oxidation by H(2) was observed. On the basis of the available evidence, a concerted mechanism for the cleavage of H(2) by metal tetraoxo compounds is proposed. Theoretical models were developed for pertinent MnO(4)(-) + H(2) transition states using density functional theory in order to differentiate between concerted [2 + 2] and [3 + 2] scissions of H(2). The density functional theory calculations strongly favor the [3 + 2] mechanism and show that the H(2) cleavage shares some mechanistic features with related hydrocarbon oxidation reactions. The calculated activation energy for the [3 + 2] pathway (DeltaH(++) = 15.4 kcal mol(-1)) is within 2 kcal mol(-1) of the experimental value.

GO GIRLS!: results from a nutrition and physical activity program for low-income, overweight African American adolescent females.

This article describes the development, implementation, and results of an intervention designed for inner-city, overweight African American adolescent women. Fifty-seven participants were recruited from four public housing developments. Participants were administered physiologic, dietary, and cognitive assessments at baseline and immediately postintervention. Each session comprised three elements: (1) an educational/behavioral activity, (2) 30 to 60 minutes of physical activity, and (3) preparation and tasting of low-fat meals. In the absence of a control group, results were compared for high and low attenders, the former defined as attending at least 50% of the sessions. High attenders (n = 26) showed more favorable 6-month posttest values for most outcomes compared with low attenders (n = 31). These effects achieved statistical significance for nutrition knowledge, low-fat practices, perceived changes in low-fat practices, and social support.

Involvement of drugs in sexual assault.

OBJECTIVE: To obtain information about the relationship of alcohol and drug usage in victims of sexual assault, including the newly identified "date rape" drugs gamma hydroxybutyrate and flunitrazepam. STUDY DESIGN: Analysis of urine samples with gas chromatography combined with mass spectrometry can identify alcohol and numerous other drugs with a high degree of specificity. This service was offered to rape treatment centers throughout the United States in May 1996; urine samples obtained from sexual assault victims suspected of drug use by history or physical examination were sent for testing at the discretion of the examiner. RESULTS: As of March 1999, a total of 2,003 specimens were analyzed. Nearly two-thirds of the samples contained alcohol and/or drugs; the predominant substances found were alcohol, present in 63%, and marijuana, present in 30%. A substantial subset of the specimens was found to contain other illicit substances, frequently in combination. GHB and flunitrazepam were found in < 3% of the positive samples. Additionally, over the two-year study period, the use of these two drugs appeared to be declining. CONCLUSION: These findings support prior data indicating that alcohol, marijuana and/or other drugs are important risk factors in sexual assault. Continued monitoring of drug use by victims of sex crimes is important, and programs that serve victims should modify protocols to reflect this.

Defining, measuring, and predicting impulsive aggression: a heuristic model.

Aggression research does not lack data--it lacks a model for integrating data. One of the problems confronting aggression researchers is the extensive body of multidisciplinary data that is difficult to synthesize to generate new directions in research. This paper proposes one solution that starts by asking "what is the minimal number of categories of concepts and measurements which are necessary to describe a person?". The answer is four categories of concepts: biological; cognitive; behavioral; environmental (physical and social). One way of many for integrating these four categories of concepts is a proposed discipline neutral heuristic model that is used herein to compare two different research approaches to the study of impulsive aggression. This comparison identifies clearly the differences in the two approaches with regard to different emphases among the four categories of constructs for each program. Using the model an example of common ground between the two approaches is sought as a basis for extending aggression research. The main conclusion of one of the research programs was that central nervous arousal is related to impulsive aggression. This program demonstrated that phenytoin will reduce impulsive aggressive acts and has an effect on CNS arousal. The other research program on impulsive aggression has been at the forefront in demonstrating the well established inverse relationship between serotonin levels and aggression. The comparison resulted in the suggestion that both serotonin and phenytoin may relate to a common neurochemical substrate which interacts in part to control CNS arousal, especially at the cortical level. The proposed heuristic model made obvious the need to use synthesizing concepts (e.g. information processing or language) which can interrelate multidisciplinary concepts and data from different research programs within the four categories of constructs when comparing interdisciplinary research.

Patterns of genital injury in female sexual assault victims.

OBJECTIVE: New colposcopic protocols allow examiners to better document genital trauma in rape victims. We report our findings on the locations and types of genital injury seen in female assault victims versus women engaging in consensual sex. STUDY DESIGN: Physical examinations were performed on 311 rape victims seen by San Luis Obispo County's Suspected Abuse Response Team between 1985 and 1993 and contemporaneously on 75 women after consensual sexual intercourse. RESULTS: Among 213 (68%) victims with genital trauma, 162 (76%) had 3.1 mean sites of injury. Comparatively, 8 (11%) consenting women had just single-site trauma. Two hundred (94%) victims had trauma at one or more of four locations, as follows: posterior fourchette, labia minora, hymen, fossa navicularis. Trauma types varied by site; tears appeared most often on the posterior fourchette and fossa, abrasions appeared on the labia, and ecchymosis was seen on the hymen. CONCLUSION: A localized pattern of genital trauma can frequently be seen in women reporting nonconsensual sexual intercourse; such findings are useful for the clinical forensic examiner.

PIP: New colposcopic protocols for US forensic examiners enable documentation of genital trauma in 87-92% of rape victims--a significant improvement over protocols based on gross visualization or toluidine blue dye enhancement. It remains unresearched, however, whether colposcopic genital findings in sexual assault victims differ substantially from those in women who have had consensual intercourse. Thus, the type, extent, and distribution of genital injuries observed through colposcopy in 311 rape victims seen by the San Luis Obispo (California) County's Suspected Abuse Response Team in 1985-93 were compared to genital changes in 75 healthy women who had engaged in consensual intercourse in the past 24 hours. 213 assault victims (68%) had evidence of anogenital trauma. Among the 178 women (57%) with nongenital trauma, 132 (74%) also had genital injury (tears, ecchymoses, abrasions, redness, and swelling). The most common trauma site was the posterior fourchette (70%). Examination findings were significantly greater at 24 hours after rape than at 72 hours or more, but almost half the women seen at 72 hours or more after assault had positive genital findings. The injury pattern was not affected by age. In the consensual sex group, trauma was noted in eight women (11%). The proportion with genital injury was significantly higher for women reporting nonconsensual sex than those reporting consensual sex.

Passive insufficiency of two-joint shoulder muscles.

This preliminary study examined the effects of full elbow flexion and full elbow extension on the end-point of active range of motion of shoulder flexion and shoulder extension respectively. The end-points were measured from lateral photographs of the right upper limbs of 30 men after they flexed and extended their shoulders with their elbows held in full flexion and full extension. Angular measurements showed that full elbow flexion limited shoulder flexion range of motion and that full elbow extension limited shoulder extension range of motion. The results indicated that passive muscle insufficiency of active shoulder flexion and extension was probably brought about by lengthening the triceps brachii and the biceps brachii muscles respectively. Clinicians are encouraged to considerthis passive insufficiency when measuring range of motion of shoulderflexion and extension and when implementing therapeutic interventions.

Wheat-kernel growth characteristics during exposure to chronic ozone pollution.

Chronic exposure to ozone (O(3)) air pollution can reduce yield in wheat; however, little is known concerning the effects of O(3) stress on kernel development. A field study was conducted to investigate the effects of chronic O(3) exposure on kernel-growth components of two soft red winter-wheat genotypes (Seven and MD5518308). Five air-quality treatments, including charcoal-filtered air (CF), non-filtered air (NF), NF + 20, and NF + 40 and NF + 80 nl O(3) liter(-1) air were applied 4 h d(-1), 5 d wk(-1) through maturity. In the case of the NF + treatments, O(3) was added to existing ambient O(3) levels. Spike samples were collected 16, 20, 24, 28, and 32 days after anthesis (DAA). Linear and quadratic equations were fitted to kernel-weight data to estimate kernel-growth rate (KGR) and kernel-fill duration (KFD). Effective filling period (EFP) and assimilate utilization (AU) were also determined. Rates of growth for individual kernels were 0.74 mg d(-1) and 1.07 mg d(-1) for the NF + 80 and CF treatments, respectively. The NF + 80 nL litter(-1) O(3) treatment significantly reduced KGR and AU compared with the CF treatment. Severn had a significantly loger KFD than MD5518308, but O(3) had no significant effect on KFD of either genotype. Each genotype had similar EFP values, and O(3) had no significant effect on EFP. Linear relationships between O(3) exposure and kernel weight suggests that O(3) effects on kernel weight begin soon after anthesis in MD5518308, but, in Severn, O(3) has a greater effect on kernel weight during the later stages of kernel development. These data suggest that decreased economic yield associated with chronic O(3) exposure is primarily the result of decreased KGR.

Colposcopy to establish physical findings in rape victims.

OBJECTIVE: Conventional rape examination protocols have been poor in yielding genital findings (10% to 30% typically). We report our experience with a revised protocol employing colposcopy to perform genital examinations of victims and to document findings. STUDY DESIGN: Physical examinations were performed on rape victims seen by San Luis Obispo County's Suspected Abuse Response Team between 1985 and 1990, and the results were reviewed for this study. RESULTS: Of 131 patients seen within 48 hours and who experienced penile penetration, 114 (87%) had positive findings. Colposcopic magnification allowed examiners to characterize these findings as acute mounting injuries, typically seen at 3, 6, and 9 o'clock on the posterior fourchette and consisting chiefly of lacerations, ecchymosis, and swelling. CONCLUSIONS: An examination protocol that includes colposcopy may be the most reliable means to document and characterize genital findings in rape victims and to evaluate whether findings may be linked to a reported sexual assault.

Cervical findings in rape victims.

The difficulty of documenting genital findings in rape victims by gross visualization is well known. However, we report two cases in which cervical findings were readily established by colposcopic examination and photography. Use of the colposcope may significantly increase the reliability of establishing findings in rape victims.

Effects of beta-carotene and retinyl palmitate on corn oil-induced superoxide dismutase and catalase in rats.

The present study was undertaken to determine the effects of beta-carotene on corn oil-induced superoxide dismutase and catalase. Six groups of male Buffalo rats were fed the following diets for 6 wk: a control diet containing recommended levels of beta-carotene and retinyl palmitate, a retinol diet containing 10 times the recommended level of retinyl palmitate, and a beta-carotene diet containing 10 times the recommended levels of beta-carotene and adequate levels of retinyl palmitate. Each vitamin combination was fed with either 5% (wt/wt) corn oil (low fat) or 20% corn oil (high fat). Plasma total beta-carotene levels were highest in the beta-carotene groups. Levels varied inversely with the level of fat in the control group and directly with fat in the beta-carotene group. Transport of beta-carotene appeared to parallel that of cholesterol in that 36 and 35%, respectively, were associated with the low density lipoprotein fraction. Accumulation of beta-carotene in the liver was apparent from the observation that levels in liver were much higher than those in plasma. Superoxide dismutase activity was much lower in the beta-carotene groups than in the retinol groups, irrespective of level of fat, and catalase activity was also lower in the beta-carotene group, but it was in proportion to the level of fat. These findings suggest that beta-carotene functions as an antioxidant in vivo.

The first simultaneous intraoperative hyperthermia and radiotherapy procedure: dog experiment and technique.

The Department of Radiation Therapy of Howard University Hospital was the first to revive (1976) the use of intraoperative radiotherapy, or direct view irradiation, using electron beam (IORTe(-)) in the United States. Since that time, this pioneering effort has gained both national and international acceptance. Now, many leading centers employ this investigational treatment modality. Recently, a new mode of cancer therapy has been gaining acceptance, namely hyperthermia (the treatment of cancer by heat). Hyperthermia has been shown, both experimentally and clinically, to improve the rate of local control (thermal enchancement ratio [TER]) when combined with radiation therapy in the treatment of cancer. Maximal TER has been observed with simultaneous or immediate application of radiation and hyperthermia for both tumor and normal tissues. Therefore, to achieve maximum therapeutic gain, selective, intraoperative, simultaneous heating and irradiation of the tumor with mechanical retraction of the normal and sensitive structures from the treatment field seems a promising alternative.There have been no published reports, to the authors' knowledge, on the combination of simultaneous IORTe(-) with intraoperative hyperthermia (IOHT). To employ this combination in human subjects, several questions must be answered first using animal models, including the technical and practical feasibility, the toxicity and morbidity, as well as the pathologic changes that may arise. The technical aspects of the first animal case, using a mongrel dog, applying simultaneous IORTe(-) and IOHT are presented.