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Background In Quebec, 6.2% of all tuberculosis (TB) isolates from Canadian-born patients are resistant to pyrazinamide (PZA) alone. The clinical significance of PZA-monoresistant (PZA(MR)) TB is unknown. Methods Canadian-born patients with PZA(MR) TB diagnosed between 1 January 1990 and 31 December 2000 and reported in a prior study were compared to randomly selected Canadian-born patients with fully susceptible isolates diagnosed within the same time period. Results A total of 318 patients were eligible, of whom 40 (12.6%) had missing outcome information. Mean total duration of treatment was respectively 9.0 and 8.9 months for those with PZA(MR) and pan-susceptible strains. Respectively 91% and 89% of PZA(MR) and pan-susceptible patients received at least 6 months of rifampin-containing treatment. Among 67 patients with PZA(MR) TB, 51 (76%) were cured, 3 (4%) relapsed, none failed treatment, and 16 (24%) died within 6 months of diagnosis. Of 211 subjects with fully susceptible isolates, 181 (86%) were cured, 2 (1%) relapsed, 2 (1%) failed treatment, and 30 (14%) died within 6 months of diagnosis. PZA monoresistance was associated with decreased odds of successful clinical outcomes compared with pan-susceptible TB (OR 0.4, 95%CI 0.2-0.8). Conclusion Patients with PZA(MR) TB had significantly worse clinical outcomes than patients with fully susceptible strains.

One of the reasons often advanced for the study of Western civilization is its history of scientific and technical prowess. Advances in science and technology have resulted in the many conveniences of modern life: air travel, automobiles, and smart phones, to name just a few. These are fruits of the Baconian project, which emphasized observation and measurement in the study of nature as part of an endeavor to “establish and extend the power and dominion of the human race itself over the whole universe.” 1 Bacon identified three inventions that separated the ancients from the moderns: the magnetic compass, gunpowder, and printing. 2 Of interest here

The ocular microenvironment is an extreme example of regional immunity. Within its microenvironment, expression of delayed type hypersensitivity (DTH) is suppressed. This immunosuppression is mediated in part by the constitutive expression of alpha-MSH. Previously we have found that alpha-MSH suppresses the production of IFN-gamma by activated effector T cells. Recently we have found that alpha-MSH can mediate induction of TGF-beta-producing T cells that act as regulatory T cells. This has encouraged us to further examine the potential for alpha-MSH to suppress T cell-mediated inflammation (autoimmune disease) and to regulate lymphokine production by effector T cells. When alpha-MSH was injected i.v. into mice at the time of peak retinal inflammation, the severity of experimental autoimmune uveitis (EAU) was significantly suppressed. Effector T cells activated in vitro in the presence of alpha-MSH proliferated and produced IL-4 and enhanced levels of TGF-beta while their IFN-gamma and IL-10 production was suppressed. The alpha-MSH-treated T cells functioned as regulatory T cells by suppressing in vitro IFN-gamma production by other inflammatory T cells. This regulatory activity was the function of alpha-MSH-treated CD4+ CD25+ T cells. Therefore, alpha-MSH mediates immunosuppression by inducing a differential expression of lymphokine production and by inducing activation of regulatory functions in T cells. This implies that alpha-MSH may take part in regional mechanisms of immunosuppression and possibly peripheral tolerance. Thus, alpha-MSH can be used to suppress autoimmune disease and possibly reestablish tolerance to autoantigens.

We study coherent phonon oscillations in GaAs/AlGaAs superlattices and multiple quantum wells as a function of the barrier width. Strong, bulklike screened LO phonons accompany bare LO phonons for thin barrier samples, whereas for thicker barrier samples, only the bare LO phonons exist. These results strongly indicate that the coherent interwell plasmons oscillating across the barrier couple to LO phonons. The technique applied is a very sensitive way of probing the superlattice--multiple quantum well transition of collective charge oscillations.

The magnetization reversal is investigated in (Ga,Mn)As thin films using magneto-optical Kerr effect. The results demonstrate a reversal behavior analogous to that observed in metallic magnetic layers (coherent rotation followed by nucleation propagation process). The dynamic study at T=20 K shows a strong increase of the coercivity with the increase of dH/dt.

Aedes albopictus (Stegomyia albopictus) (Diptera: Culicidae) has probably supplanted Aedes aegypti (Stegomyia aegypti) throughout most of its historical range in the U.S.A., although Ae. aegypti still exists in large coastal cities in southern Florida. We measured salt concentrations in field containers along an axis perpendicular to the coast and examined intraspecific outcomes in these species under different salt concentrations in a factorial study using varying intra- and interspecific densities in different conditions of salinity to order to determine if salt could mitigate the documented competitive superiority of Ae. albopictus. Salt in field containers declined away from the coast, with maximal values similar to our lower salt concentrations. Egg hatching and short-term survival of pupae and late instars were not affected by salt concentrations; survival of early instars of both species decreased at higher concentrations. In high salt conditions, Ae. aegypti achieved higher survival. In the longterm experiment, both species displayed longer development times. Salt did not affect interactions for either species; Ae. aegypti survived in the highest salt conditions, regardless of density. The tolerance of Ae. aegypti to high salt concentrations may allow it to use coastal containers, although because salt did not mediate interspecific interactions between Ae. aegypti and Ae. albopictus, the ultimate effects of salt on the coexistence of these species or exclusion of either species remain unknown.

In helically symmetric protein assemblies, fluorescence resonance energy transfer (FRET) spectroscopy can be used to determine the radial coordinates of fluorescent probes attached to specific amino acid side chains. This is done by separately labeling monomers with donor and acceptor probes, mixing them in different proportions, allowing the mixtures to self-assemble, and then measuring the fluorescence intensity. Provided the helical symmetry is known, and provided the donor- and acceptor-labeled monomers associate randomly, the radial coordinate of the probes can be calculated. Using different probe pairs, two different research groups have employed this method to show that the Cys-374 site of the actin filament (F-actin) is located at a radius of either 35-40 A [Taylor, D.L., Reidler, J., Spudich, J.A., & Stryer, L. (1981) J. Cell Biol. 89, 362-367] or 20-25 A [Kasprzak, A.A., Takashi, R., & Morales, M.F. (1988) Biochemistry 27, 4512-4522]. We have reinvestigated these disparate radius determinations using the same probe pairs employed by these authors with a wide range of acceptor molar fractions. Our results suggest that labeling actin with probes makes the association of monomers significantly nonrandom. This may be avoided by polymerizing actin in the presence of phalloidin. The nonrandomness also can be modeled using stochastic simulation. Taking the average diameters of the probes into account, we conclude that in phalloidin-stabilized F-actin, Cys-374 lies at a radius of (17-18) +/- 5 A. This value is consistent with radial coordinates determined by electron microscopy.(ABSTRACT TRUNCATED AT 250 WORDS)

In this letter, magnetization reversal is investigated in (Ga,Mn)As thin films using the magneto-optical Kerr effect. A Stoner–Wohlfart model, modified to take into account the existence of magnetic reversal discontinuities associated with nucleation and propagation phenomena allows us to estimate most of the characteristic constants. These results demonstrate a reversal behavior analogous to that observed in metallic magnetic layers (coherent rotation followed by a nucleation propagation process). The dynamic study at T=20 K shows a strong increase of the coercivity with the increase of dH/dt. This effect is related to the random distribution of Mn magnetic ions in the lattice.

Continuous‐wave (CW) terahertz (THz) generation has been successfully achieved by low‐temperature grown (LTG) In1−xGaxAs (x = 0.47) epitaxial layer as a THz emitter and a photomixer module with dual‐wavelength laser as an optical beat source. The reflectance decay spectroscopy revealed a carrier lifetime of ∼ 2.5 ps in LTG‐InGaAs layer grown at 220 °C and subsequently in‐situ annealed at 550 °C for 10 min. The THz ouput characteristics are demonstrated in the range of 0.3–0.8 THz.

We develop highly‐resistive (i.e. low‐carrier‐density) and ultrafast Fe‐ion implanted InGaAs layers for the applications of THz photomixer and photoconductive switch. The measured Hall mobility, sheet resistance, carrier density, and carrier lifetime of the optimized 1.2‐μm‐thick Fe‐implanted InGaAs layer are 3.4×102 cm2/Vs, 0.24 MΩ, 6.5×1014 cm−3, and 0.13ps, respectively.

A significant charge transfer, which differs from tunneling, over thick AlxGa1−xAs barrier in GaAs/AlxGa1−xAs asymmetric double quantum wells is studied by cw photoluminescence excitation (PLE) and time‐resolved photoluminescence. It is found that 300‐A‐thick Al0.3Ga0.7As barrier is universally ‘‘leaky’’ with transport time of ∼300 ps, while AlAs and AlAs/GaAs digital alloy barriers with same thickness are not. Aided by a model calculation, we suggest that the intrinsic inhomogeneities in the alloy, which recent x‐ray and scanning tunneling microscope studies revealed, may be responsible.

Chimeric angiotensin II (AngII) receptors constructed of portions of the AT2 receptor substituted into the AT1 receptor revealed the AT2 third extracellular loop and seventh transmembrane-spanning domain as major determinants for the ability to bind and activate in response to the AT2 receptor-selective agonist CGP 42112A. Radioligand binding experiments showed that chimeric AngII receptors possessing the AT2 third extracellular loop and seventh transmembrane-spanning domain bound CGP 42112A with high affinity approaching that of the wild-type AT2 receptor. The presence of the AT2 third extracellular loop appeared sufficient for high-affinity CGP 42112A binding, which was further enhanced by the additional presence of the AT2 seventh transmembrane-spanning domain. Experiments with PD 123319, losartan, and [Sar1,Ile8]-AngII showed that increases in binding affinity associated with these domains were specific for CGP 42112A. Use of phosphoinositide hydrolysis as a functional index to measure activation of these chimeric AngII receptors further demonstrated that the AT2 seventh transmembrane-spanning domain was especially critical for CGP 42112A to act as an agonist. The absence of the AT2 seventh transmembrane-spanning domain prohibited CGP 42112A-induced activation of these receptors, even in the presence of high concentrations of CGP 42112A sufficient to saturate the binding sites. This study is the first to identify binding determinants of the AT2 receptor that are selective for CGP 42112A, and indicates that these determinants are at least partially distinct from those for the AT2-selective antagonist PD 123319. These differences may be a factor in the pharmacodynamic difference between these two ligands.

The availability of large EST (Expressed Sequence Tag) databases has led to a revolution in the way new genes are cloned. Difficulties arise, however, due to high error rates and redundancy of raw EST data. For these reasons, one of the first tasks performed by a scientist investigating any EST of interest is to gather contiguous ESTs and assemble them into a larger virtual cDNA. The REX (Recursive EST eXtender) algorithm described in this paper completely automates this process by finding ESTs that can be clustered on the basis of overlapping bases, and then assembling the contigs into a consensus sequence. By combining the clustering and assembly steps, REX can quickly generate assemblies from EST databases that are frequently updated without having to preprocess the data. A consensus assembly method is used to correct miscalled bases and remove indel errors. A unique feature of this method is that it addresses the issues of splice variants and unspliced cDNA data. Since REX is a fast greedy algorithm, it can address the problem of generating a database of assembled sequences from very large collections of EST data. A procedure is described for creating and maintaining an Assembled Consensus EST database (ACE) that is useful for characterizing the large body of data that exists in EST databases.

Deployment of endovascular grafts composed of a metallic stent surrounded by expanded polytetrafluoroethylene (ePTFE) stretches the polymer beyond its original dimensions, altering the structural characteristics of the ePTFE. We hypothesized this structural modification would alter the healing response associated with the implant. In this study, 4 mm i.d. of ePTFE (30 microns internodal distance) vascular grafts were balloon dilated using angioplasty balloons having final diameters of 6 (1.5X), 8 (2X), 10 (2.5X), 12 (3X), and 18 (4.5X) mm. Following balloon dilatation of the ePTFE, a circular punch (6 mm in diameter) was used to prepare polymer samples for implantation. The ePTFE circular patches were implanted within subcutaneous tissue and epididymal fat pads of male Sprague-Dawley rats. After 5 weeks, the implants were removed and analyzed for fibrous capsule formation, inflammation, and neovascularization associated with the material. Histological analysis revealed the formation of fibrous capsules only with control subcutaneous implants. The inflammatory response associated with subcutaneously implanted ePTFE was decreased significantly following balloon dilatation to at least 2.5 times the original diameter of the graft. In contrast, ePTFE implanted within adipose tissue demonstrated a significantly greater inflammatory response following balloon dilatation when compared to control implants. Only ePTFE balloons dilated to 6 mm and implanted within adipose tissue demonstrated neovascularization to any extent. These data suggest the structural modifications incurred by ePTFE following balloon dilatation dramatically affect the inflammatory response associated with an implant. Therefore, polymeric materials used for endovascular graft technology require designs that consider changes in polymer healing inherent to device design.

Locally advanced prostate carcinoma is usually not curable with surgery or radiation therapy. Primary hormone therapy is an alternative therapeutic option, but contemporary prospective studies of the outcomes of such therapy are not available.The authors conducted a prospective, hospital-based study of gonadal androgen ablation with deferred antiandrogen therapy in 103 men with prostate carcinoma clinically classified as T3-4NXM0. The median potential follow-up was 51 months (range, 36-74 months), and the median period of observation was 43 months (range, 6-74 months).Each patient experienced regression of the primary tumor, and none experienced significant morbidity from the primary tumor during the study period. The projected 5-year cause specific, metastasis free, PSA disease free (no PSA elevation1.0 ng/mL after the beginning of antiandrogen therapy), and all-cause survival rates were 84%, 84%, 68%, and 58%, respectively.Primary hormone therapy is a reasonable treatment option for locally advanced prostate carcinoma in elderly men or in men with significant comorbid disease who request therapeutic intervention.

We study coherent phonon oscillations in GaAs/AlxGa1−xAs MQW’s with varying x and fixed well and barrier widths of 100A. We have observed large plasmon-phonon coupling in x=0.2 MQW, although it is generally believed that the 2D nature of plasmon makes the plasmon-phonon coupling very difficult. One possible explanation for this phenomenon is the bulk-like, growth direction plasmon oscillations mediated by the anomalously large well-to-well coupling for small x (x

The search for less invasive treatments for cardiovascular disease has lead to the development of endovascular stent grafts, metallic and alloy stents surrounded by prosthetic vascular graft material. Introduced intravascularly, the deployment of stent grafts requires balloon dilatation of the device which results in expansion of the stent along with the vascular graft material. We hypothesized that balloon dilatation of stent grafts would alter the physical structure of the prosthetic graft material. In this study, noncompliant angioplasty balloons were used to dilate expanded polytetrafluoroethylene (ePTFE), a material commonly used for endovascular stent-graft technology. The maximal outer diameter (inflated balloon within the lumen) and the recoiled outer diameter (balloon removed) of two types of ePTFE, 3-mm inside diameter (i.d.) thin wall (30-micron internodal distance) and 4-mm i.d. standard wall (30-micron internodal distance), were measured to compare material recoil. Following balloon dilatation, ePTFE samples were prepared for scanning electron microscopic examination and the following parameters were measured: wall thickness, internodal distance, nodal width, interfiber distance, and fiber width. Following primary dilatation, both types of ePTFE recoiled approximately 20% regardless of inflated balloon diameter. However, following eight repetitive balloon dilatations, recoil decreased to approximately 10%. Scanning electron microscopic analysis revealed variations in internodal distance and significant decreases in wall thickness, nodal thickness, and interfiber distance. Fiber width was significantly decreased following dilatation of 3 mm, but not 4 mm ePTFE. Our data support our initial hypothesis that balloon dilatation alters the structure of ePTFE.

The intraocular microenvironment is an immune-privileged site where immunogenic inflammation is suppressed. Suppression of immunogenic inflammation has been associated with immunosuppressive factors found in aqueous humor produced by ocular tissues. To further understand the mechanisms suppressing immunogenic inflammation in the eye, we have examined the production of lymphokines by primed T-cells activated in the presence of aqueous humor.Enriched in vivo primed T-cells were T-cell receptor-stimulated in the presence of fresh aqueous humor. The culture supernatant was assayed for IFN-gamma and IL-4 by sandwich ELISA. TGF-beta production by T-cells stimulated in the presence of aqueous humor was assayed by a TGF-beta bioassay of the culture supernatant and by quantitative RT-PCR for TGF-beta 1 mRNA expression. Aqueous humor-treated T-cells were assayed for their capacity to suppress IFN-gamma production by stimulated, primed T-cells.Aqueous humor-enhanced proliferation but irreversibly suppressed production of both IFN-gamma and IL-4 by in vitro-activated, in vivo-primed T-cells. Aqueous humor induced in vivo primed T-cells to produce TGF-beta in vitro, and these TGF-beta-producing T-cells suppressed IFN-gamma production by other T-cells activated in co-cultures.Aqueous humor alters the functional program of TCR-ligand-activated, primed T-cells, converting the cells to TGF-beta-producing regulatory cells.

Since postoperative pain is associated with morbidity and increased hospital resources, reducing pain should improve patient care. Enhanced education and individualized feedback were introduced at the study hospital to promote anesthesiologists' use of patient-controlled analgesia, nonsteroidal antiinflammatory drugs, epidural morphine, and nerve blocks. After 6-mo baseline, anesthesiologists at the study hospital attended educational seminars and received literature about pain management. Personalized feedback forms were then distributed to each anesthesiologist showing the management and rates of pain for their patients. Practice was as usual at a control hospital. Pain in the postanesthesia care unit (PACU) and for 6-h post-PACU discharge was assessed using PACU records and interviews for 3413 patients at the study hospital and 1753 at the control hospital. From the baseline to the feedback period, the absolute increase in the proportion of patients receiving at least one promoted strategy was greater at the study hospital than at the control hospital (44.9% vs 22.8% P < 0.0001). Mean pain scores with activity decreased at both hospitals; study hospital 7.6 (7.3-7.8, 99% confidence interval) to 6.2 (5.9-6.5); control hospital 7.3 (6.9-7.6) to 6.1 (5.7-6.4). Education and feedback increased the use of pain management strategies at the study hospital. The modest change in patient outcome was unlikely related to directed interventions.

Because the ultimate purpose of new medical knowledge is to achieve improved health outcomes, physicians need to possess and use this knowledge in their practice. The authors introduced enhanced education and individualized feedback to reduce postoperative nausea and vomiting (PONV). The primary objective was to increase anesthesiologists' use of preventive measures to reduce PONV, and the secondary objective was to determine whether patient outcomes were improved.After obtaining hospital ethics committee approval, the effect of education and feedback on anesthesiologist performance and the rate of PONV in major surgery elective inpatients during a 2-yr period was assessed. After baseline data collection (6 months), anesthesiologists at the study hospital received enhanced education (8 months) and individualized feedback (10 months). Parallel data collection was performed at a control hospital at which practice was continued as usual. The education promoted preventive measures (antiemetic premedication, nasogastric tubes, droperidol, metoclopramide). Individualized feedback provided the number of patients receiving promoted measures and the rate of PONV. The mean percentage of anesthesiologists' patients receiving at least one promoted measure and the rate of PONV were compared with baseline levels.At the study hospital, there was a significant increase in the mean percentage of the anesthesiologists' female patients receiving a preventive measure as well as a significant increase in the use of droperidolor = 1 mg (P0.05) for all patients. The use of other promoted measures was unaffected. Absolute rates of PONV were unaffected at the study hospital until the post-feedback period (decrease of 8.8% between baseline and post-feedback (P = 0.015)).It was demonstrated that enhanced education and individualized feedback can change anesthesiologists' practice patterns. The actual benefit to patients from use of preventive measures was limited when used in the everyday clinical situation. Therefore, only modest decreases in PONV were achieved, despite the use of preventive measures.

Evidence continues to accumulate that strengthens the proposal of heterogeneity within both the AT1 and the AT2 receptor subtypes. Pharmacologic, biochemical and immunological studies of AT2 receptors expressed in N1E-115 cells strengthen the hypothesis of AT2 receptor heterogeneity. However, it is important to reassess these studies, especially in terms of how these results correlate with other reports of AT2 receptor heterogeneity. For example, AT2 receptor immunoreactivity was absent in some neuronal regions which have previously been proposed to express the AT2 receptor subtype. In particular, AT2 receptor staining was not seen in the inferior olive, a region which is known to express a high density of AT2 receptors. Upon first examination, these results were somewhat troubling. However, when compared with earlier reports, these results should not have been unexpected. For instance, Tsutsumi and Saaverdra previously have shown that AT2 receptors in the locus coeruleus are sensitive to the actions of guanine nucleotides, while AT2 receptors in the inferior olive are insensitive (21). These antisera were raised against a population of AT2 receptors which are sensitive to GTP gamma S and therefore, the lack of AT2 receptor staining in the inferior olive, as well as the presence of AT2 receptor immunoreactivity in the locus coeruleus, confirms and extends these earlier reports. In addition the AT2 receptors expressed in the locus coeruleus have been shown to be functionally distinct from AT2 receptors in the inferior olive. In this regard, Ang II has been shown to depress glutamate-induced EPSPs in the locus coeruleus, an effect which is mediated through the AT2 receptor (19). Conversely, AT2 receptors have been shown to increase the firing rate of neurons in the inferior olive (20). Collectively, these results would predict that staining should be absent in the inferior olive using these AT2-directed antisera. Indeed, in view of these earlier physiological and pharmacological studies, the presence of AT2 receptor immunoreactivity in the inferior olive would have been surprising. The most convincing example of AT2 receptor heterogeneity is the characterization of AT2 receptors present in N1E-115 cells. Separation of solubilized N1E-115 membranes by heparin-Sepharose chromatography generates two populations of AT2 receptors which are pharmacologically and biochemically distinct. In particular, CGP42112A was approximately 2 orders of magnitude more selective for Peak III AT2 receptors than was PD123319. Binding activity of Peak I and Peak III AT2 receptor populations also differed in their responses to GTP gamma S and DTT treatment. Lastly, the AT2-directed antisera, raised against the Peak I population of AT2 receptors, were not able to immunodetect the Peak III population of AT2 receptors in immunoblot analysis, or immunoprecipiatate AT2 binding activity from Peak III material. Pharmacological, biochemical and immunological analysis of the AT2 receptor clone isolated from N1E-115 cells revealed that it has the identical characteristics or properties of the Peak III receptor. The AT2 receptor isolated from N1E-115 cells exhibited a similar pharmacology as the Peak III AT2 receptor, in that CGP42112A was more effective at displacing 125I-Ang II binding activity than was PD123319. The AT2 receptor clone was also shown to be insensitive to the actions of GTP gamma S, as well as demonstrated increased binding activity in the presence of DTT, identical to the Peak III AT2 receptor. Lastly, immunoblot analysis of membranes prepared from COS-1 cells transfected with the AT2 receptor cDNA from N1E-115 cells did not demonstrate any immune-specific bands with the AT2-directed antisera. Characterization of an AT2 receptor cDNA isolated from N1E-115 cells reveals that this clone is identical to the Peak III type of AT2 receptor.

The diverse actions of angiotensin II (AngII) are mediated by cell surface receptors. Molecular cloning techniques have identified two distinct subtypes of AngII receptors referred to as AT1 and AT2. It is now well accepted that multiple forms of the AT1 receptor exist, but similar diversity of the AT2 subtype has not been conclusively demonstrated. Nonetheless, several converging lines of evidence do suggest that multiple AT2 receptors may be present in brain and cultured neuron-like cells lines. For instance, some AT2 receptors are regulated by guanine nucleotides and sulfhydryl-reducing agents, whereas others are insensitive. AT2 receptor populations also exhibit differing pharmacological profiles particularly with respect to their affinity for peptidic and non-peptidic ligands. Moreover, a recently developed anti-AT2 polyclonal antisera reveals a unique pattern of immunohistochemical staining in brain and it does not immunoreact with the recently cloned AT2 receptor. Collectively, these results support the hypothesis of multiple AT2 receptors at least within the CNS. Future studies should reveal whether these putative AT2 receptor subtypes result from unique genes or cell-specific post-translational modifications of a single gene product.

A few years ago, lattice model studies indicated that compactness could induce polymer chains to develop protein-like secondary structures. Subsequent off-lattice studies have found the amounts of induced structure to be relatively small. Here we use distance geometry to generate random conformations of compact poly-alanine chains of various chain lengths. The poly-alanine chains are subjected only to compactness and excluded volume constraints; no other energies or conformational propensities are included in the chain generation procedure. We find that compactness leads to considerable stabilization of secondary structure, but the absolute amount of secondary structure depends strongly on the criteria used to define helices and sheets. By loose criteria, much secondary structure arises from compactness, but by strict criteria, little does. The stabilization free energy of secondary structure provided by compactness, however, appears to be independent of criteria. Since real helices and sheets in proteins can be identified by strict criteria, we introduced small energy perturbations to compact poly-alanine chains using the AMBER force field. Small refinements produced good alpha-helices. For beta-sheets, however, larger refinements are necessary. Compactness appears to impart stability, but not much structural specificity, to secondary structures in proteins. Compactness acts more like diffusion as a force, a result of ensemble statistics, than like pair interactions such as hydrogen bonding.

The calcifying aponeurotic fibroma is a rare, benign neoplasm that often presents in the palms or soles of young male children. Microscopic examination of this tumor demonstrates atypical fibroblasts, foci of calcification, and patches of chondroid differentiation. The neoplasm's highly cellular architecture, locally aggressive growth pattern, and tendency to recur may lead to a misdiagnosis of fibrosarcoma and subsequent amputation. This manuscript presents a review of the literature and a unique case involving the digits of the foot.

Increasingly good quality case management is a necessary part of assuring appropriate and timely access to home care and other community-based services. This article focuses on how to develop a program to monitor the quality of case management services. It includes discussion of an approach for thinking about quality assurance, identifies objectives that are appropriate for quality assurance in case management settings, and provides suggestions for developing quality assurance activities in case management settings.

Lanthanum hexaboride (LaB6) is investigated for its potential as a low work‐function photocathode for high brightness e‐beam applications. Thin films of LaB6 at room temperature are shown to have quantum efficiencies of 0.2×10−3 at 442 nm excitation but readily form an inhibiting oxide. This oxide is easily removed by in situ 500 eV Ar+ ion sputtering, which restores photoemission for over 30 min at an oxygen partial pressure of 10−9 Torr.

The effect of argon ion bombardment on the structure and properties of thick copper films was studied. Primary deposition variables were ion flux, ion energy, substrate temperature, and substrate type. The effects of ion bombardment are profoundly different at high energy (600 eV) as opposed to low energy (62 eV). Trends in crystallographic texture, microhardness, crystallite size, and resistivity are significantly different at different ion energies on all substrates examined. At high energy, the substrate dependence of properties is small while a large dependence is seen at lower energy. This work demonstrates the independence of ion energy and ion flux as control parameters in property modification using ion‐assisted deposition processes.

In situ measurements during MeV ion bombardment at room temperature are used to study the superlinear increase of resistivity with fluence which occurs in irradiated ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{x}}$. The functional form of the resistivity increase is found to be exactly exponential for O and As ion irradiation, confirming previous results of lower precision. For low ion damage rates we find deviations from the exponential dependence at low doses. We show that these are caused by an unidentified phase transformation, occurring during the irradiation, which lowers the resistivity of the samples. Annealing of resistivity increments caused by brief irradiations occurs at room temperature, indicating that radiation-induced defects are mobile. The rate of annealing is strongly sample dependent, but in all cases the transformation induced by a small dose of irradiation causes a reduction in the resistivity of the sample. We suggest that the reduction in resistivity may be due to ordering on the oxygen sublattice.

The effect of ion bombardment on alloy film stress was studied by coevaporating W and Si in the presence of 100 and 400 eV Ar+ ion bombardment at room temperature, 350 and 500 °C. In the absence of ion bombardment, internal stress increases and becomes more tensile as deposition temperature increases. At room temperature, increasing ion bombardment causes the stress to go from tensile to compressive. At 350 °C tensile stress increases as a function of ion flux and decreases slightly at higher flux value. At 500 °C, the effect on stress due to ion bombardment is less pronounced. The correlation between the effect of ion bombardment on stress, deposition temperature, and the structure of the material is discussed using the concept of enhanced surface diffusion and local atomic rearrangement as a mechanism responsible for ion beam stress modification. By using this mechanism, we explain the diminished effect of ion bombardment on stress in the WSi2 films that contain compound phases compared to the amorphous...