Stabilizing Lead-Salt Diode Lasers: Understanding and Controlling Chaotic Frequency Emission

Lead-salt tunable diode lasers (TDLs) are the only devices currently available that can generate tunable monochromatic radiation at arbitrary wavelengths between 3 and 30 micrometers and are particularly useful for high-resolution spectroscopy over a wide range of spectral regimes. Detailed observations of TDLs show that the observed instrumental linewidth is actually a temporal average of many narrow (less than 0.5 megahertz) emission "modes." The time scale characteristic of these "modes," which appear to be of relatively constant intensity, is of the order of a microsecond. The laser's behavior is highly suggestive of a chaotic process, that is, seemingly random excursions of a dynamic variable (frequency) within a bounded range. This report shows experimentally that TDL emissions are indeed chaotic. Furthermore, in a simple and robust fashion, this chaotic behavior has been successfully controlled with the use of recent techniques that take advantage of chaos to produce a narrow band laser output.     

Redesigning trypsin: alteration of substrate specificity

A general method for modifying eukaryotic genes by site-specific mutagenesis and subsequent expression in mammalian cells was developed to study the relation between structure and function of the proteolytic enzyme trypsin. Glycine residues at positions 216 and 226 in the binding cavity of trypsin were replaced by alanine residues, resulting in three trypsin mutants. Computer graphic analysis suggested that these substitutions would differentially affect arginine and lysine substrate binding of the enzyme. Although the mutant enzymes were reduced in catalytic rate, they showed enhanced substrate specificity relative to the native enzyme. This increased specificity was achieved by the unexpected differential effects on the catalytic activity toward arginine and lysine substrates. Mutants containing alanine at position 226 exhibited an altered conformation that may be converted to a trypsin-like structure upon binding of a substrate analog.     

A modification for the theoretical infiltration equations based on physical properties of the soil

A modification based on capillary flow type was proposed for three theoretical infiltration equations accounting for the physical properties of the soil. The equations were (a) Green and Ampt, (b) Fletcher, and (c) Fok and Hansen. The derived modified equations were tested by computer programs on four undisturbed field soils on which the mass infiltration and soil properties had been measured. Of the three equations, (b) exhibited the best adherence to the data points and (a) and (c) were reasonably good. In general, the types of relations revealed by the field measurements were such as would tend to linearize if the log of the mass infiltration was plotted against the log of time. The breaks exhibited by some of the soils could be explained by changes in the soil properties at that point.     

Estimating theoretical radiation‐use efficiency for kale crops

Establishing the radiation‐use efficiency (RUE) of forage brassica crops will aid our understanding of their photosynthetic performance. The concept of RUE has been developed for cereals and legumes, but there is limited information for forage brassica crops. Three experiments defining the influence of different sowing dates on ‘Gruner’ kale (Brassica oleracea acephala L.) dry matter production were conducted at Hastings (Hawkes Bay) and Lincoln (Canterbury) in New Zealand between 2002 and 2009. These trials were also evaluated for radiation interception and RUE. Delayed sowing increased RUE in two out of three experiments across sites: from 1·93 g MJ^?1 photosynthetically active radiation (PAR) for December‐sown crops to 2·72 g MJ^?1 PAR (P < 0·001) for January‐sown crops at Hastings and from 1·50 for September‐sown crops to 2·00 g MJ^?1 PAR (P < 0·001) for November‐sown crops at Lincoln. The different sowing dates and years of experimentation provided a range of mean temperatures (from 13 to 16°C) during the vegetative period. Across years and sowing dates, RUE was strongly correlated with mean temperature (R² = 0·81) and sowing date (R² = 0·64), but weakly correlated with season length (R² = 0·11) and dry matter (R² = 0·002). There was also a strong correlation (R² = 0·83) between sowing date and mean temperature. The increase in RUE with delayed sowing was therefore mainly attributed to increased mean temperatures. Radiation‐use efficiency increased at about 0·41 g MJ^?1 for each 1°C increase from 13 to 16°C.     

Transpalpebral ultrasonographic measurement of the optic nerve sheath diameter in healthy dogs

Objective

To develop a reference range for ultrasonographically measured optic nerve sheath diameter (ONSD‐US) in dogs. We hypothesized that ONSD‐US can be measured reliably and is associated with weight but not age, sex, or body condition score (BCS), and that the relationship between weight and ONSD‐US in dogs is allometric due to canine size variations.

Design

Prospective, observational study.

Setting

University teaching hospital.

Animals

Seventy‐eight healthy adult dogs.

Interventions

The ONSD was measured by a standardized transpalpebral approach.

Measurements and Main Results

Regression analysis showed the relationship between weight and ONSD was better fit with a linear model (R² = 0.8510) than an allometric model (R² = 0.7917). Multiple regression analysis showed ONSD is associated with weight (P < 0.0001), age (P = 0.0021), and BCS (P = 0.0007), but not with sex. Dominance analysis showed 94.6% of the variance explained by the model was due to weight. Intraclass correlation coefficient (ICC) analysis showed excellent interobserver (ICC = 0.9338–0.9608) and intraobserver (ICC = 0.9893) reliability.

Conclusions

These results suggest that ONSD‐US may be reliably measured in dogs using our described transpalpebral approach, and we have calculated prediction intervals based on body weight. Future studies are needed to determine if ONSD‐US measurements are associated with intracranial hypertension as shown in human medicine.     

云南省曲靖市1995－2005年兽药质量抽检情况分析

以曲靖市兽药监察所最近十年的兽药质量监督抽检报告为基础材料进行统计分析，反映兽药质量监督抽检工作情况及兽药质量状况。     

Pituitary-adrenal function in dogs with acute critical illness

OBJECTIVE: To evaluate pituitary-adrenal function in critically ill dogs with sepsis, severe trauma, and gastric dilatation-volvulus (GDV). DESIGN: Cohort study. ANIMALS: 31 ill dogs admitted to an intensive care unit (ICU) at Washington State University or the University of Pennsylvania; all dogs had acute critical illness for < 48 hours prior to admission. PROCEDURES: Baseline and ACTH-stimulated serum cortisol concentrations and baseline plasma ACTH concentrations were assayed for each dog within 24 hours after admission to the ICU. The change in cortisol concentrations (Delta-cortisol) was calculated for each dog. Morbidity and mortality data were recorded for each patient. RESULTS: Overall, 17 of 31 (55%) acutely critically ill dogs had at least 1 biochemical abnormality suggestive of adrenal gland or pituitary gland insufficiency. Only 1 (3%) dog had an exaggerated response to ACTH stimulation. Dogs with Delta-cortisol < or = 83 nmol/L were 5.7 times as likely to be receiving vasopressors as were dogs with Delta-cortisol > 83 nmol/L. No differences were detected among dogs with sepsis, severe trauma, or GDV with respect to mean baseline and ACTH-stimulated serum cortisol concentrations, Delta-cortisol, and baseline plasma ACTH concentrations. CONCLUSIONS AND CLINICAL RELEVANCE: Biochemical abnormalities of the hypothalamic-pituitary-adrenal axis indicative of adrenal gland or pituitary gland insufficiency were common in critically ill dogs, whereas exaggerated responses to ACTH administration were uncommon. Acutely ill dogs with Delta-cortisol < or = 83 nmol/L may be more likely to require vasopressors as part of the treatment plan.