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71.
Data relating to variations in hem lengths (presented in Part I) are further assessed in the context of a range of economic indicators. The results indicate, firstly, that the pace of fashion change has not been notably affected by changes in a variety of economic indicators and, secondly, that, contrary to popular mythology, hem lengths do not appear to have risen and fallen in unison with changes in the economy.  相似文献   
72.
The effect of depth of intake and controlled discharge of heated waters (Δ T—10°C) on a natural phytoplankton community in a cold water lake was studied using polyethylene enclosures. Changes in plankton species composition and cell concentrations were used as indicators of temperature effects. Of three intake-discharge arrangements studied (surface intake-surface discharge; deep intake-deep discharge; deep intake-surface discharge) only the first design produced statistically significant increases in plankton numbers. A deep intake-surface discharge resulted in the least biological and physical changes in the lake water. Phytoplankton species succession in the heated water was similar to patterns observed in the open lake.  相似文献   
73.
Gelatinase A, a member of the matrix metalloproteinase (MMP) family, is secreted possessing an 80 amino acid N-terminal propeptide that must be removed in order to generate the active enzyme. Purified progelatinase A was activated to 38% of maximum by a 6 h incubation at 37 degrees C with equimolar concentrations of trypsin-activated interstitial collagenase (another MMP). The increase in activity was accompanied by cleavage of the M(r) 72,000 progelatinase A to the M(r) 66,000 active enzyme that has Y81 as its N-terminus. At low concentrations, progelatinase A was processed via an inactive intermediate, suggesting that its activation is a biphasic process. This was confirmed by the action of collagenase on proE375-->A (a mutant of progelatinase A that cannot become active) because, in this instance, only an M(r) 68,000 species with L38 as the N-terminus was produced. The remaining propeptide amino acids to Y81 could be readily removed by added active gelatinase A, indicating that collagenase works by generating an intermediate that is susceptible to autolytic activation. Although relatively slow, the rate of activation could be increased approximately 10-fold by the addition of 100 micrograms/mL heparin. This binds to the C-terminal domain of collagenase and progelatinase A and presumably acts as a template that positions the reactants close to one another. Collagenase activated by trypsin retains 8 or 14 amino acids of its propeptide.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
74.
BACKGROUND: Water under high pressure can produce vaginal injury. Previous reports suggest that postmenarcheal maturation and the presence of a vaginal foreign body contributed to water slide injuries in women. METHODS: A case of a vaginal injury from a water slide in a premenarcheal patient is presented. A literature review of water-related vaginal injuries in adults and children compares the mechanism of injury with that previously reported. RESULTS: The patient underwent operative repair of her injury. CONCLUSIONS: Vaginal injury in premenarcheal patients may result from a water slide. The emergency physician must be aware of this potential injury mechanism and the need for complete examination under anesthesia when vaginal bleeding is present.  相似文献   
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Two pressure-controlled inlets (PCI) have been designed and integrated into the Aerodyne Aerosol Mass Spectrometer (AMS) inlet system containing an aerodynamic aerosol lens system for use in airborne measurements. Laboratory experiments show that size calibration and mass flow rate into the AMS are not affected by changes in upstream pressure (P 0 ) of the PCI as long as the pressure within the PCI chamber (P PCI ) is controlled to values lower than P 0 . Numerous experiments were conducted at different P PCI , P 0 , and AMS lens pressures (P Lens ) to determine particle transmission efficiency into the AMS. Based on the results, optimum operating conditions were selected which allow for constant pressure sampling with close to 100% transmission efficiency of particles in the size range of ~ 100–700 nm vacuum aerodynamic diameter (d va ) at altitudes up to ~ 6.5 km. Data from an airborne field study are presented for illustration.  相似文献   
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A recently developed method to rapidly quantify the elemental composition of bulk organic aerosols (OA) using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) is improved and applied to ambient measurements. Atomic oxygen-to-carbon (O/C) ratios characterize the oxidation state of OA, and O/C from ambient urban OA ranges from 0.2 to 0.8 with a diurnal cycle that decreases with primary emissions and increases because of photochemical processing and secondary OA (SOA) production. Regional O/C approaches approximately 0.9. The hydrogen-to-carbon (H/C, 1.4--1.9) urban diurnal profile increases with primary OA (POA) as does the nitrogen-to-carbon (N/C, approximately 0.02). Ambient organic-mass-to-organic-carbon ratios (OM/OC) are directly quantified and correlate well with O/C (R2 = 0.997) for ambient OA because of low N/C. Ambient O/C and OM/OC have values consistent with those recently reported from other techniques. Positive matrix factorization applied to ambient OA identifies factors with distinct O/C and OM/OC trends. The highest O/C and OM/OC (1.0 and 2.5, respectively) are observed for aged ambient oxygenated OA, significantly exceeding values for traditional chamber SOA,while laboratory-produced primary biomass burning OA (BBOA) is similar to ambient BBOA, O/C of 0.3--0.4. Hydrocarbon-like OA (HOA), a surrogate for urban combustion POA, has the lowest O/C (0.06--0.10), similar to vehicle exhaust. An approximation for predicting O/C from unit mass resolution data is also presented.  相似文献   
80.
1. Frequency-domain spectral analysis of stationary ECG R-R intervals was made by fast Fourier transformation (FFT) in conditions of monitored arterial blood pressure and respiratory activity in diethyl-ether-anaesthetized and pithed adult rats. This technique yields a number of parameters which allow quantitative evaluation of the non-random distribution of the mean values obtained in time-domain studies. The frequency-analysis method enables the overall heart rate variability to be broken down into its various constituents, which are differently affected by physiological loading and capable of selective reactivity to pharmacological agents. 2. The low-frequency spectral component obtained by breaking down the total spectral density power, i.e. the appropriate variability signal (band width < 0.15 Hz) and a higher-frequency band corresponding to spontaneous (0.80-1.60 Hz) or artificially imposed (0.75 Hz) respiratory activity were estimated and their integrated areas evaluated as absolute powers or normalized fractional values. 3. The power of the high-frequency spectral component increased in all animal preparations under treatment with prazosin, dl-propranolol, endothelin-1 and the angiotensin converting enzyme (ACE) inhibitors captopril, lisinopril, quinapril and ramipril. The power of the low-frequency band increased under alpha-r atriopeptin and ACE inhibitors in the pithed preparations only, and decreased in the anaesthetized animals. 4. The new power spectrum features and trends detected indicate that these time-independent, model-dependent cardiovascular and respiratory markers are subject to some form of complex peptidergic control. 5. The relative roles of the various factors operating in the genesis of these short-term changes in spectral power in the low- and high-frequency bands cannot be interpreted as indicating a reciprocal push-pull relationship between sympathetic and parasympathetic control. 6. The study findings, however, can be interpreted as providing evidence of a different and to some extent alternative form of integrative cardiovascular control persisting in the pithed rats (i.e. in the 'peripheral', CNS-destroyed preparations). 7. New areas of theoretical and applied research are being developed in the (auto)classification of (iso)receptors and drug analogues through exploration of multiple physiological and pharmacokinetic parameters in the frequency-domain. Furthermore, model-independent frequency-domain methods not requiring stationary data will afford scope for even more significant developments by separating the overlapping dynamic processes from a whole series of correlated effects.  相似文献   
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