All optical switching of reflectivity and transmissivity by anonlinear sandwich

A simple model system comprised of a thin nonlinear layer sandwiched between two glass plates is demonstrated. This nonlinear sandwich allows the investigation of both the transmitted and reflected beams for all-optical switching. With a thermal (negative) nonlinearity high-contrast switching is obtained within several nanoseconds. The authors also show for the first time, the avoidance of multiple thresholds and associated beam breakup for a nonsaturating nonlinearity for both the transmitted and reflected beams. This promises cascadability of all optical devices based on the nonlinear interface     

A sequence in the 5'' flanking region confers progestin responsiveness on the human c-myc gene

Sarcoidosis is a systemic granulomatous disease of undetermined etiology in which the immune system is overstimulated. Management of the patient with sarcoidosis entails continuity of patient care far beyond disease, even into remission. Care is comprehensive, including all involved organ systems, coordination of specialty consultations and services, and includes diagnostic tests. Therapeutic decisions are the responsibility of the primary care practitioner. Prognosis of sarcoidosis is not uniformly good. Patients can die. Subacute sarcoidosis patients usually do not require pharmacologic therapy. Chronic sarcoidosis may require long-term treatment for years to indefinitely. Corticosteroids are still the drugs of choice and other therapy is now available. Health organizations and private nonprofit support groups are available for patient education and assistance. Close support must still come from the family unit. Sarcoidosis may occur in family members in different cohorts at all ages in life and in any racial or ethnic group. The second in a two-part series on management of the patient with sarcoidosis, this article describes coordination of care and considers community, prevention, and family aspects of the disease.     

Monitoring of hematopoietic recovery after autologous stem cell transplantation by analysis of G alpha 16 mRNA and CD34 surface glycoprotein

The hematopoiesis-specific G protein alpha subunit G alpha16 was shown to be expressed in early normal and malignant hematopoietic cell lines and has been suggested to play an important role in signal transduction of hematopoiesis. We previously demonstrated a strict correlation of G alpha16 mRNA and CD34 antigen expression in peripheral blood stem cells (PBSC). In PBSC mobilization, both markers are detectable at the time of hematopoietic recovery and progenitor cell release. In this study the possible use of G alpha16 determination in peripheral blood samples for monitoring patients undergoing stem cell transplantation was investigated. Normal peripheral blood is negative for G alpha16 expression. In all five patients G alpha16 mRNA expression appeared shortly before the time of blood cell recovery. When tested together with CD34 (three cases) a pattern different from CD34 antigen expression was found, reflecting a different mechanism of action. In two cases with different time points of leukocyte and platelet recovery G alpha16 mRNA was detected at both time points but not in the interval, thus suggesting a role of G alpha16 in multipotent precursor cells. CD34 mRNA tested in three patients was not detected at any time; this argues for different regulation of CD34 and G alpha16 mRNA. G alpha16 may be used as an indicator of hematopoietic recovery after autologous stem cell transplantation, suggesting that there are cell type-specific G protein-mediated signal transduction pathways of early hematopoiesis.     

Particle size and aggregation effects on magnetite reactivity toward carbon tetrachloride

Nanoparticulate magnetite is found in many natural and engineered environments. This study characterized the reactivity of this material toward carbon tetrachloride (CCl4). Particle diameter plays an important role, with nominal (9 nm) magnetite suspensions exhibiting greater reactivity on both mass (k(m)) and surface area normalized (k(SA)) bases than (80 nm) magnetite suspensions. For the (9 nm) suspension, the aggregation state of the particles affects the measured km values. At 0.001 M ionic strength and pH 7, k(m) (=0.052-0.139 L g(-1) h(-1)) was as much as seven times larger than at 1 M (k(m) = 0.025-0.030 L g(-1) h(-1)). This decrease in reactivity with an increase in ionic strength is related to the measured diameter of the aggregates present in solution, thus implicating aggregate size as an important variable. This work is the first to indicate that both particle size and aggregation state must be considered when evaluating the reactivity of nanoparticle suspensions with groundwater contaminants.     

Temperature dependent variations in the lamellar structure of poly(l-lactide)

Time- and temperature-dependent SAXS and WAXS experiments on poly(l-lactide) were used (i) to establish the relationships between the crystallization temperature, the crystal thickness and the melting point, (ii) to follow recrystallization processes during heating, and (iii) to detect perturbations of the crystalline order. The studies showed several peculiarities: (i) although no solid state thickening occurs during a crystallization, crystal thicknesses are with values between 11 and 20 nm very large (ii) crystal thicknesses and long spacings have a minimum at 120 °C and increase for both higher and lower crystallization temperatures. The anomalous behavior at low crystallization temperatures is to be related with a disordering of the crystal lattice (iii) there exists an extended temperature range where crystal thicknesses change in controlled manner by recrystallization processes (iv) as it appears, a triple point where the fluid, the crystalline and a mesomorphic phase coexist is located near to normal pressure and a temperature of 190 °C.     

Influence of the steel plate on the friction behavior of automotive wet disk clutches

Friction behavior is the key parameter for the design of automotive wet disk clutches. On the one hand, the Coefficient of Friction (CoF) level should be high to transmit torque efficiently. On the other hand, the clutch requires a positive slope of the CoF over sliding speed for good controllability, high comfort, and a low tendency to shudder. Clutches used in automatic or dual-clutch transmissions mostly use organic friction lining. These friction systems tend to have low CoF at low sliding speeds due to their high requirements regarding shifting comfort. Nevertheless, they show high values of CoF at high sliding speeds.

This study investigates the influence of different steel plate finishes on friction behavior in different application-relevant operation modes such as brake shift, unsteady slip, and micro slip. Each of these operation modes requires an accurate CoF measurement at different sliding speed ranges. Therefore, we use different test rig setups. We characterize the steel plates by their areal surface topography measured with an optical system using focus variation. We discuss differences in the friction behavior of the corresponding tribological systems at different operating conditions.

Results show an influence of the steel plate surface finish on the CoF level. Therefore, the surface finish of the steel plate influences the functional behavior of wet disk clutches and engineers should consider the surface finish in the early design phase. We discuss the correlation between commonly used surface parameters and friction parameters.