Hypothyroidism and Thyroid Substitution: Historical Aspects

The last part of the 19th century was a period of great achievements in medicine and endocrinology. The thyroid gland evolved from being considered a rudimentary structure to an organ related to specific diseases. The singular importance of iodine became acknowledged. Graves-Basedow's disease was described. Surgical treatment evolved with extraordinary speed. Theodor Kocher observed that the clinical picture in patients after total thyroidectomy was similar to the one seen in cretinism. In 1850, the first case of hypothyroidism or myxedema was described. Less than 50 years later, effective treatment was introduced. Another 50 years later, autoimmune thyroiditis was ascertained as the most frequent cause of hypothyroidism (in areas with no iodine deficiency). This paper gives a short survey of the history of hypothyroidism and its treatment

Heavy doping effects in high efficiency silicon solar cells

A model for bandgap shrinkage in semiconductors is developed and applied to silicon. A survey of earlier experiments, and of new ones, give an agreement between the model and experiments on n- and p-type silicon which is good as far as transport measurements in the 300 K range. The discrepancies between theory and experiment are no worse than the discrepancies between the experimental results of various authors. It also gives a good account of recent, optical determinations of band gap shrinkage at 5 K

A survey of unified constitutive theories

The state of the art of time temperature dependent elastic viscoplastic constitutive theories which are based on the unified approach werre assessed. This class of constitutive theories is characterized by the use of kinetic equations and internal variables with appropriate evolutionary equations for treating all aspects of inelastic deformation including plasticity, creep, and stress relaxation. More than 10 such unified theories which are shown to satisfy the uniqueness and stability criteria imposed by Drucker's postulate and Ponter's inequalities are identified. The theories are compared for the types of flow law, kinetic equation, evolutionary equation of the internal variables, and treatment of temperature dependence. The similarities and differences of these theories are outlined in terms of mathematical formulations and illustrated by comparisons of theoretical calculations with experimental results which include monotonic stress-strain curves, cyclic hysteresis loops, creep and stress relaxation rates, and thermomechanical loops. Numerical methods used for integrating these stiff time temperature dependent constitutive equations are reviewed

Experimental investigation of the excess charge and time constant of minority carriers in the thin diffused layer of 0.1 ohm-cm silicon solar cells

An experimental method is presented that can be used to interpret the relative roles of bandgap narrowing and recombination processes in the diffused layer. This method involves measuring the device time constant by open-circuit voltage decay and the base region diffusion length by X-ray excitation. A unique illuminated diode method is used to obtain the diode saturation current. These data are interpreted using a simple model to determine individually the minority carrier lifetime and the excess charge. These parameters are then used to infer the relative importance of bandgap narrowing and recombination processes in the diffused layer

Unified constitutive models for high-temperature structural applications

Unified constitutive models are characterized by the use of a single inelastic strain rate term for treating all aspects of inelastic deformation, including plasticity, creep, and stress relaxation under monotonic or cyclic loading. The structure of this class of constitutive theory pertinent for high temperature structural applications is first outlined and discussed. The effectiveness of the unified approach for representing high temperature deformation of Ni-base alloys is then evaluated by extensive comparison of experimental data and predictions of the Bodner-Partom and the Walker models. The use of the unified approach for hot section structural component analyses is demonstrated by applying the Walker model in finite element analyses of a benchmark notch problem and a turbine blade problem

Constitutive modeling for isotropic materials (HOST)

The results of the first year of work on a program to validate unified constitutive models for isotropic materials utilized in high temperature regions of gas turbine engines and to demonstrate their usefulness in computing stress-strain-time-temperature histories in complex three-dimensional structural components. The unified theories combine all inelastic strain-rate components in a single term avoiding, for example, treating plasticity and creep as separate response phenomena. An extensive review of existing unified theories is given and numerical methods for integrating these stiff time-temperature-dependent constitutive equations are discussed. Two particular models, those developed by Bodner and Partom and by Walker, were selected for more detailed development and evaluation against experimental tensile, creep and cyclic strain tests on specimens of a cast nickel base alloy, B19000+Hf. Initial results comparing computed and test results for tensile and cyclic straining for temperature from ambient to 982 C and strain rates from 10(exp-7) 10(exp-3) s(exp-1) are given. Some preliminary date correlations are presented also for highly non-proportional biaxial loading which demonstrate an increase in biaxial cyclic hardening rate over uniaxial or proportional loading conditions. Initial work has begun on the implementation of both constitutive models in the MARC finite element computer code

Friction and wear studies of some PEEK materials

The friction and wear behavior of several types of PEEK polymers and composites were studied. The influence of carbon fiber, lubricant and thermally conductive fillers were evaluated, as well as the effects of contact load and temperature.  The tests were done using a reciprocating ball-on-disc set-up. The materials were tested under the load of 5 N and 15 N, at room temperature, 80°C, 120°C and 150°C. The difference between the materials was substantial, with a friction coefficient varying between 0.03 and 0.3 for the different materials at 120°C. PEEK with carbon fiber filler showed an improvement in both friction and wear compared to unfilled PEEK. When adding lubricant, PTFE, to the composite the friction and wear were improved even more. PEEK with thermally conductive filler on the other hand had both highest friction and wear. Increasing the temperature slightly decreased both friction and wear for most of the PEEK materials. At 150°C, only the composite with PTFE lubricant had a low friction and wear

Is Cycle 24 the Beginning of a Dalton-Like Minimum?

The unexpected development of cycle 24 emphasizes the need for a better way to model future solar activity. In this article, we analyze the accumulation of spotless days during individual cycles from 1798-2010. The analysis shows that spotless days do not disappear abruptly in the transition towards an active sun. A comparison with past cycles indicates that the ongoing accumulation of spotless days is comparable to that of cycle 5 near the Dalton minimum and to that of cycles 12, 14 and 15. It also suggests that the ongoing cycle has as much as 20 \pm 8 spotless days left, from July 2010, before it reaches the next solar maximum. The last spotless day is predicted to be in December 2012, with an uncertainty of 11 months. This trend may serve as input to the solar dynamo theories.Comment: 10 pages, 5 figures. The final publication is available at http://www.springerlink.co

Systemic and intraperitoneal interleukin‐6 system during the first year of peritoneal dialysis

Perit Dial Int. 2006 Jan-Feb;26(1):53-63. Systemic and intraperitoneal interleukin-6 system during the first year of peritoneal dialysis. Pecoits-Filho R, Carvalho MJ, Stenvinkel P, Lindholm B, Heimbürger O. Division of Renal Medicine and Baxter Novum, Karolinska Institutet, K-56, Huddinge University Hospital, 141 86 Stockholm, Sweden. [email protected] Comment in: Perit Dial Int. 2006 Jan-Feb;26(1):35-7. Abstract OBJECTIVE: To investigate if intraperitoneal and systemic interleukin-6 (IL-6) and soluble IL-6 receptor (sIL-6R) are related to each other and to peritoneal solute transport rate (PSTR). DESIGN: Longitudinal study in retrospectively selected patients. SETTING: Peritoneal dialysis (PD) unit of a university-based hospital. PATIENTS AND METHODS: 31 PD patients on treatment with conventional glucose-based solutions participated in a longitudinal study. IL-6 and sIL-6R were measured in plasma and overnight effluent, both at baseline and after 12 +/- 2 months on PD. C-reactive protein (CRP) and serum albumin were used as surrogate markers of inflammation. PSTR of small solutes was evaluated using the dialysate-to-plasma ratio (D/P) of creatinine after a 4-hour dwell; PSTR of large solutes was evaluated using the 24-hour D/P ratio of albumin. RESULTS: D/P creat increased over time (0.67 +/- 0.15 vs 0.80 +/- 0.11, p or = median had higher (p or = median [24.7 (16.5 - 38.5) pg/mL] compared to patients with IL-6 < median [14.1 (10 - 25.7) pg/mL]. Neither CRP nor albumin changed over time on PD, although they were closely linked to plasma IL-6 levels. A strong positive correlation was found between D/P creat and dialysate IL-6 (rho = 0.77, p < 0.0001) at baseline, but not at 1 year. In contrast, there was a significant correlation between D/P creat and dialysate sIL-6R (rho = 0.39, p < 0.05) at 1 year, but not at baseline. At 1 year, 17 patients with increasing PSTR had higher increases in dialysate IL-6 (28 +/- 26 vs -21 +/- 78 pg/mL, p < 0.05) and levels of dialysate sIL-6R (693 +/- 392 vs 394 +/- 274 pg/mL, p = 0.05) compared to patients with stable PSTR (n = 11). Patients who had peritonitis presented higher baseline serum IL-6 concentration (6.8 +/- 1.0 pg/mL) compared with patients without peritonitis (4.0 +/- 0.6 pg/mL, p < 0.05). Finally, both at baseline and after 1 year, there were significant correlations between plasma and dialysate IL-6 (rho = 0.46, p < 0.05, and rho = 0.40, p < 0.05) respectively. CONCLUSIONS: These findings indicate that, (1) intraperitoneal and systemic inflammation increase in PD patients during the first year of therapy; (2) intraperitoneal and systemic inflammation may be interrelated and the IL-6 system may be the link; (3) the IL-6 system (both intraperitoneal and systemic) is associated with PSTR, particularly in the early phase of PD treatment, in which small and large solute transport are linked. Signs of a transition between acute and chronic inflammation were observed in the follow-up evaluation. Inflammation may, at least in part, be responsible for the development of a high PSTR, and this could be one reason for the high mortality in patients with high PSTR. PMID: 16538876 [PubMed - indexed for MEDLIN