Characterizing physical habitat preferences and thermal refuge occupancy of brook trout (Salvelinus fontinalis) and Atlantic salmon (Salmo salar) at high river temperatures

Anthropogenic influences, including climate change, are increasing river temperatures in northern and temperate regions and threatening the thermal habitats of native salmonids. When river temperatures exceed the tolerance levels of brook trout and Atlantic salmon, individuals exhibit behavioural thermoregulation by seeking out cold‐water refugia – often created by tributaries and groundwater discharge. Thermal infrared (TIR) imagery was used to map cold‐water anomalies along a 53 km reach of the Cains River, New Brunswick. Trout and salmon parr did not use all identified thermal anomalies as refugia during higher river temperature periods (>21°C). Most small‐bodied trout (8–30 cm) were observed in 80% of the thermal anomalies sampled. Large‐bodied trout (>35 cm) required a more specific set of physical habitat conditions for suitable refugia, that is, 100% of observed large trout used 30% of the anomalies sampled and required water depths >65 cm within or adjacent to the anomaly. Densities of trout were significantly higher within anomalies compared with areas of ambient river temperature. Salmon parr were less aligned with thermal anomalies at the observed temperatures, that is, 59% were found in 65% of the sampled anomalies; and densities were not significantly different within/ outside anomalies. Salmon parr appeared to aggregate at 27°C, and after several events over 27°C variability in aggregation behaviour was observed – some fish aggregated at 25°C, others did not. We stipulate this is due to variances of thermal fatigue. Habitat suitability curves were developed for velocity, temperature, depth, substrate, and deep water availability to characterize conditions preferred by fish during high‐temperature events. These findings are useful for managers as our climate warms, and can potentially be used as a tool to help conserve and enhance thermal refugia for brook trout and Atlantic salmon in similar systems.     

Real-time organic aerosol chemical speciation in the indoor environment using extractive electrospray ionization mass spectrometry

Understanding the sources and composition of organic aerosol (OA) in indoor environments requires rapid measurements, since many emissions and processes have short timescales. However, real-time molecular-level OA measurements have not been reported indoors. Here, we present quantitative measurements, at a time resolution of five seconds, of molecular ions corresponding to diverse aerosol-phase species, by applying extractive electrospray ionization mass spectrometry (EESI-MS) to indoor air analysis for the first time, as part of the highly instrumented HOMEChem field study. We demonstrate how the complex spectra of EESI-MS are screened in order to extract chemical information and investigate the possibility of interference from gas-phase semivolatile species. During experiments that simulated the Thanksgiving US holiday meal preparation, EESI-MS quantified multiple species, including fatty acids, carbohydrates, siloxanes, and phthalates. Intercomparisons with Aerosol Mass Spectrometer (AMS) and Scanning Mobility Particle Sizer suggest that EESI-MS quantified a large fraction of OA. Comparisons with FIGAERO-CIMS shows similar signal levels and good correlation, with a range of 100 for the relative sensitivities. Comparisons with SV-TAG for phthalates and with SV-TAG and AMS for total siloxanes also show strong correlation. EESI-MS observations can be used with gas-phase measurements to identify co-emitted gas- and aerosol-phase species, and this is demonstrated using complementary gas-phase PTR-MS observations.     

2.4 GHz continuously variable ferroelectric phase shifters using all-pass networks

Continuously variable ferroelectric (BST on sapphire) phase shifters based on all-pass networks are presented. An all-pass network phase shifter consists of only lumped LC elements, and thus the total size of the phase shifter is kept to less than 2.2 mm /spl times/ 2.6 mm at 2.4 GHz. The tunability (C/sub max//C/sub min/) of a BST interdigital capacitor is over 2.9 with a bias voltage of 140 V. The phase shifter provides more than 121/spl deg/ phase shift with the maximum insertion loss of 1.8 dB and the worst case return loss of 12.5 dB from 2.4 GHz to 2.5 GHz. By cascading two identical phase shifters, more than 255/spl deg/ phase shift is obtained with the maximum insertion loss of 3.75 dB. The loss figure-of-merit of both the single- and double-section phase shifters is over 65/spl deg//dB from 2.4 GHz to 2.5 GHz.     

如何用硅振荡器替代晶体和陶瓷谐振器

对于绝大多数微控制器时钟电路而言，硅振荡器是一种简单且有效的解决方案。与晶体和陶瓷谐振器不同，基于硅材料的定时器具有抗振动、抗撞击和抗电磁干扰的优点。同时，硅振荡器不需要严格匹配的定时元件和线路板走线。     

Regression of severe atherosclerotic plaque in patients with mild elevation of LDL cholesterol

BACKGROUND: Intensive risk factor reduction in patients with dyslipidemias and coronary atherosclerosis has been shown to result in alterations in coronary artery morphology and reduced clinical events. However, the impact of such interventions in populations with relatively normal levels of low-density lipoproteins (LDL) is unclear. METHODS: To test the hypothesis that intensive risk factor reduction results in angiographic regression in patients with only mildly elevated levels of LDL, 14 patients with angiographically proven coronary atherosclerosis were entered into the University of California Davis Coronary Artery Disease Regression Program and intensively treated with pharmacologic and nonpharmacologic interventions for 2 years. Quantitative angiography was performed prior to and after 2 years of therapy to determine changes in coronary artery diameter. RESULTS: As a result of this program, dietary fat intake was reduced by 58% and LDL fell from 120 +/- 7 mg/dL to 104 +/- 6 mg/dL (p = 0.05). The average diameter of the measured arterial locations (including all 53 stenoses and 292 nondiscrete regions) on study entry was 2.74 +/- 0.05 mm. After 24 months, there was a net increase in arterial diameter (regression) of +0.05 +/- 0.04 mm to 2.81 +/- 0.05 mm (p = 0.01). While there was no significant change in the average diameter of discrete stenoses, all 8 lesions > or = 50% initial diameter narrowing regressed, with a mean diameter change of + 0.2 mm. Conversely, only 1 of 8 mild lesions < or = 20% regressed, while 4 progressed. Intermediate lesions (20% to 50%, n = 37) had balanced progression and regression. CONCLUSIONS: When examined as a continuous variable, there was a significant linear correlation between initial lesion severity (% stenosis) and the extent of regression (mm). Therefore, risk factor reduction (dietary therapy, exercise, psycho-social counseling, and lipid lowering therapy) in patients with only mild dyslipidemia results in angiographic regression of more severe lesions (> 50% initial stenosis), but does not prevent progression of mild lesions (< 20%). These findings demonstrate that intensive risk factor reduction in patients with only mild elevation of lipids beneficially influences the morphology of the most severe lesions.     

Differential transforming growth factor-beta secretion in adenocarcinoma and squamous cell carcinoma of the uterine cervix

Tumor cells from eight freshly isolated cervical cancers (i.e., four adenocarcinomas and four squamous carcinomas) were analyzed for their production of the immune-inhibitory cytokine transforming growth factor-beta (TGF-beta) in vitro. All fresh adenocarcinomas secreted significant levels of TGF-beta (mean 397, range between 207 and 782 pg/ml/10(5) cells/48 hr). In contrast, no detectable TGF-beta was present in the supernatants from the four fresh squamous carcinoma cultures (P < 0.001). These data suggest that major differences in the secretion of the immunoinhibitory cytokine TGF-beta exist between squamous cell carcinomas and adenocarcinomas of the uterine cervix. Furthermore, these findings suggest that at least some of the differences in the natural biologic behavior, as well as in the response to radiation treatment, between these two histologic types of cervical cancer could be related to differences in secretion of this immune-inhibitory cytokine.     

Voluntary head stabilization in space during oscillatory trunk movements in the frontal plane performed in weightlessness

The ability voluntarily to stabilize the head in space during lateral rhythmic oscillations (0.59+/-0.09 Hz) of the trunk has been investigated during microgravity (microG) and normal gravity (nG) conditions (parabolic flights). Five healthy young subjects, who gave informed consent, were examined. The movements were performed with eyes open or eyes closed, during phases of either microG or nG. The main result was that head orientation with respect to vertical may be stabilized about the roll axis under microG with, as well as without vision, despite the reduction in vestibular afferent and muscle proprioceptive inputs. Moreover, the absence of head stabilization about the yaw axis confirms that the degrees of freedom of the neck can be independently controlled, as was previously reported. These results seem to indicate that voluntary head stabilization does not depend crucially upon static vestibular afferents. Head stabilization in space may in fact be organized on the basis of either dynamic vestibular afferents or a short-term memorized postural body schema.     

Structure-permeation relations of met-enkephalin peptide analogues on absorption and secretion mechanisms in Caco-2 monolayers

Due to the low effective permeabilities of peptides at many absorption sites, their structure-permeation relations are of high interest. In this work structure-permeation relations of Met-enkephalin analogues are presented using confluent Caco-2 cells as an in vitro permeation model. Four model peptides (Met-enkephalin, [D-Ala2]Met-enkephalin, [D-Ala2]Met-enkephalinamide, and metkephamid) were tested in terms of permeability, lipophilicity, charge, and molecular size. Permeability coefficients (P(eff)) across Caco-2 cells were low, 3.3 x 10(-8) to 9.5 x 10(-8) cm s-1, and were similar to typical paracellular markers. No correlation of permeability and the log(apparent octanol/buffer partition coefficient) was observed. A 40-fold increase of the permeability of metkephamid in the presence of 10 mM EDTA suggested a significant contribution of paracellular transport. Independent support for this conclusion was obtained by visualizing the pathway of the fluorescein isocyanate isomer I 1-metkephamid by confocal laser scanning microscopy (CLSM). The fluorophore-labeled peptide was observed in the intercallular space only. Metkephamid permeabilities were found to be direction-specific. Permeabilities from basolateral to apical (b-to-a) were significantly higher (ca. 4-fold) than in the opposite (a-to-b) direction. The addition of verapamil equalized the permeabilities in the a-to-b and b-to-a directions, suggesting the involvement of a P-glycoprotein-mediated secretion mechanism. Similar observations were obtained with [D-Ala2]Met-enkephalinamide, but not with Met-enkephalin and [D-Ala2]Met-enkephalin. In contrast to the other analogues, metkephamid and [D-Ala2]Met-enkephalinamide are positively charged at neutral pH, as demonstrated by their isoelectric points (pl = 8.6 for [D-Ala2]Met-enkephalinamide and metkephamid and 5.3 for [D-Ala2]Met-enkephalin and Met-enkephalin). The data is in agreement with the literature showing that most compounds secreted by the P-glycoprotein transporter carry a positive charge.     

Comparison of single-fiber and macro electrode recordings: relationship to motor unit action potential duration

The factors contributing to the duration of a motor unit action potential (MUAP) are believed to be well known, with both manual measurements and computer simulations agreeing with respect to MUAP durations approaching 10 ms. In this investigation, it is clearly demonstrated that use of a wide-open amplifier bandpass combined with signal-to-noise ratio enhancement results in MUAP durations approaching 30 ms recorded with either a macro or single-fiber electrode. Why the clinically recorded MUAP duration differs significantly from these physiologic durations is discussed. A hypothesis is presented whereby the major contributing factor toward MUAP duration is the total time of action potential transmembrane current flow along the muscle fiber from end-plate zone to musculotendinous junction.