ST Conditions Research Articles

Heat-Treatment Studies on Dissimilar Ti-Alloy EB Weld Joints

Ti3Al2.5V alloy is lean alpha plus beta titanium alloy having two phase microstructure at room temperature (RT) and has beta transus temperature (Tβ) about 9350C and Ti6Al4V-ELI (extra low interstitials) alloy has two phase structure at RT and has Tβ about 9750C. The samples were electron beam welded (EBW) after the optimization of weld parameters on bead-on plate of 6mm thickness of Ti6Al4V-ELI alloy. The samples were heat treated (solution treated, ST at 9100C for 20 minutes water quenched, WQ and aged at 5100C for 8 hours and air cooled, AC to RT). The specimens were tested to evaluate mechanical properties in as-welded, solution treated and aged conditions. The improvement in the tensile strength was 810 MPa to 897 MPa in as weld to ST conditions, and comparable in STA condition (887 MPa). The improvement in yield strength was 760 MPa to 782 MPa and 848 MPa in as-welded, ST and aged conditions respectively. While there is a decreasing trend in the ductility (%EL) of the joint in three conditions (as weld, ST and STA). In all the specimens evaluated at different heat treated conditions the failure location was within parent Ti3Al2.5V alloy (parent metal away from the weld interface) as confirmed through OM (optical microscopy).

Isozyme systems as markers of genetic deterioration in stored seeds of Brassicaceae species

The main objective of this study was to determine if isozyme systems can be used as markers of genetic deterioration in Brassicaceae seed accessions under different storage conditions. Seed samples of Brassica oleracea, Cardaria draba, Erysimum cheiri, Iberis sempervirens and Rapistrum rugosum were stored for periods of 9 to 30 years at -10°C and 3-4% seed moisture content (long-term or LT conditions) and at 5°C and uncontrolled relative humidity (RH) (short-term or ST conditions). Starch Gel Electrophoresis (SGE) was used to analyse six enzyme systems oriented to determine the genetic deterioration of the accessions studied. The results obtained show that long-term storage conditions (LT) were extremely effective in maintaining the viability of seeds of the five Brassicaceae species studied. The final germination percentages reached by seeds from LT samples ranged from 75 to 100%, while the germination percentages of ST samples (except for B. oleracea) were very low (from 0 to 10%). Similar conclusions were obtained studying the integrity of electrophoretic bands for several isozymes. Two enzyme systems were of special interest: malate dehydrogenase and alcohol dehydrogenase.

Latitudinal Variation in Physiological and Behavioral Responses of Nest‐Guarding Smallmouth Bass to Common Recreational Angling Practices

AbstractManagement policies related to catch‐and‐release (CR) angling of smallmouth bass Micropterus dolomieu vary widely across the geographic distribution of the species. Some jurisdictions, principally in the northern latitudes, prohibit or limit angling efforts that target nesting male smallmouth bass, whereas angling during the nesting period is generally unregulated in southern jurisdictions. Existing studies of individual‐level angling impacts on nesting smallmouth bass have primarily been conducted in the north; thus, the extent to which these findings are relevant to other regions is unknown. In the current study, we sought to systematically evaluate the rates of nest abandonment by nesting smallmouth bass subjected to common angling practices (CR treatment: Brief angling and no exposure to air; air exposure [AE] treatment: Exhaustive angling and 3 min of AE) and tournament practices (simulated tournament [ST] treatment: Exhaustive angling, 2 h of live‐well retention, and 3 min of AE prior to release) across a latitudinal gradient encompassing virtually the entire south‐north range of smallmouth bass (i.e., southern Missouri [MO], southern Ontario [SON], and northern Ontario [NON]) and compared these treatment groups with nonangled controls. We also quantified the extent to which physiological disturbance associated with angling varied across latitudes (peripheral populations [MO and NON] versus the intermediate‐latitude population [SON]). Whole‐blood lactate and glucose levels were highest in fish subjected to ST conditions, indicating increased stress; this pattern was conserved across all latitudes (although there was some evidence of intraspecific variation in stress response). Additionally, the pattern of brood abandonment was similar among fish at all three latitudes; ST fish exhibited the highest rates of nest abandonment (MO: Control = 9.1%, CR = 0%, AE = 9.1%, ST = 100%; SON: control = 10%, CR = 10%, AE = 10%, ST = 50%; NON: control = 7.7%, CR = 0%, AE = 9.1%, ST = 50%). Interestingly, fish from the most southerly latitude, where regulations are the most liberal, abandoned nests at higher rates than did fish from the other latitudes. Collectively, these data reveal that the reproductive success of individual smallmouth bass can suffer from interaction with anglers, particularly in a tournament context, regardless of the region. Further study is needed to determine the extent to which individual nest success is relevant to recruitment and how this relationship varies across latitudes.

Residual haptic sensation following stroke using ipsilateral stimulation

In 1987, Weiskrantz and Zhang described a stroke patient with severe somatosensory loss who, nevertheless, demonstrated impressive residual sensory performance when required to touch the affected limb with her ipsilesional...

Vectorcardiographic ST deviations related to increased heart rate in the absence of ischemia in an experimental pig model

The electrocardiographic ST segment may change when heart rate (HR) increases. We aimed to analyze vectorcardiographic ST relation and myocardial conditions during controlled HR increases in anesthetized pigs. The relative parameters ST change vector magnitude and ST change vector angle were calculated at paced HRs ranging from 85 to 175 beats per minute. ST change vector magnitude increased from baseline 6.3 ± 1.3 to 26.0 ± 3.1 μV ( P < .01; range, 4-50 μV) at HR 175 beats per minute with similar changes in ST change vector angle, whereas the absolute parameter ST vector magnitude demonstrated a heterogeneous pattern without any systematic relation to HR changes. Microdialysis results from left ventricular wall, with analysis of glucose, lactate, and pyruvate, showed no sign of ischemia during pacing. Potassium concentrations did not change during pacing. We conclude that significant HR-related ST vector changes can occur in the absence of myocardial ischemia.

Experimental study of PAH formation in laminar counterflow CH 4[sbnd]N 2/O 2[sbnd]N 2 and C 3H 8[sbnd]N 2/O 2[sbnd]N 2 nonpremixed flames

We studied polycyclic aromatic hydrocarbon (PAH) formation in laminar counterflow CH 4 N 2/O 2 N 2 and C 3H 8 N 2/O 2 N 2 nonpremixed flames using a gas chromatograph-mass spectrometer (GC-MS) under widely varying experimental conditions. In this paper we describe the effect of varying the flame-controlling parameter on the formation of PAHs. The formation of most PAHs is enhanced by increasing the strain rate regardless of fuel species and the stoichiometric mixture fraction, Z st . Increasing the dilution levels slightly suppresses PAH formation. However, the effect is quantitatively weak. PAH formation also is suppressed as Z st increases. However, the quantitative dependence of PAH formation on Z st variation is different between CH 4 flames and C 3H 8 flames. Naphthalene is the most abundant compound under all experimental conditions in CH 4 flames. On the other hand, for C 3H 8 flames, naphthalene is the most abundant compound in the range of smaller Z st while acenaphthylene is abundant under larger Z st conditions. For all experiments, under small Z st conditions, small-molecular-mass PAHs including naphthalene have significant concentration. Large-molecular-mass PAHs including acenaphthylene, which are mostly 2- and 3-ring, are produced mainly for larger values of Z st , when nonpremixed flames are established in the fuel stream. The formation behavior of PAHs in the counterflow nonpremixed flame is classified into two groups for C 3H 8 flames. One is the PAH group that has formation behavior similar to naphthalene, and the other is the PAH group that has formation behavior similar to acenaphthylene. It is experimentally observed that the effect of varying the initial C/O ratio on the PAH formation of nonpremixed flames is similar to that of previously reported numerical predictions for C 2H 2 premixed flames.

SPONTANEOUS MUTATIONAL GENOTYPE-ENVIRONMENT INTERACTION FOR FITNESS-RELATED TRAITS IN DROSOPHILA MELANOGASTER.

Spontaneous mutations were allowed to accumulate for 104-161 generations in 113-176 inbred lines, independently maintained by a single brother-sister mating per generation, all of them derived from a completely homozygous population of Drosophila melanogaster. In each of two to three consecutive generations, all lines were scored for fecundity, egg-to-pupa and pupa-to-adult viabilities, both in the standard laboratory culture medium (ST) and in three harsh media differing from the former by a single factor: higher temperature (HT), higher NaCl concentration (HSC), or a much reduced concentration of nutrients (D). Relative to the standard medium, productivity (fecundity × viability) decreased by 25% (HT), 66% (HSC), and 80% (D). In each medium, mutational variances of those traits and mutational covariances between all possible pairs were calculated from the between-line divergence (codivergence). Mutational correlations between character states in different media were also obtained. Because we used inbred lines, those estimates were mainly due to the accumulation of mildly detrimental mutations, deleterious mutations of large effect being underrepresented. For all traits, mutational heritabilities ranged from 1.41 × 10-4 to 11.24 × 10-4 , and did not increase with intensified environmental harshness. Mutational correlations between character states in different media were usually not large (average absolute value 0.31), reflecting a high degree of environmental specificity of the mutations involved. In our results, mutations quasi-neutral in ST conditions and mildly detrimental in more stressful media were not, as a class, important. Mutational correlations between fecundity and egg-to-pupa viability were small and positive in all media. Those involving pupa-to-adult viability were positive in HT, nonsignificant in HSC, and negative in ST and D, showing how the genetic covariance structure of quantitative traits in populations may change in variable environments.

P407 Central inhibitory mechanisms are impaired in focal dystonia a transcranial magnetic stimulation (TMS) study

This systematic review and meta-analysis was conducted across studies using transcranial magnetic stimulation to investigate corticospinal excitability and inhibition in response to a dual task (DT). Quantitative analysis was performed on eleven controlled studies that had included healthy participants over the age of 18 years. Results showed a small effect size for increased corticospinal excitability for DT conditions (SMD = 0.207; p = .217, and a small effect size (SMD = −0.253) demonstrating a significant decrease in corticospinal inhibition for DT conditions (p = .019). Meta-regression demonstrated that neither age, task type, or task prioritisation accounted for the high variability in effect sizes between studies. A number of possible sources of within study bias are identified, which reduced the level of evidence for study findings. The results show overall changes in corticospinal responses between ST and DT conditions; however further research is necessary to investigate variables that could account for differences in corticospinal responses between studies.

The development of water-intake regulation during schedule-induced polydipsia

Water intake by rats exhibiting asymptotic levels of schedule-induced polydipsia during a fixed-interval (FI) 1-min food schedule was decreased by reducing the diameter of the drinking spout orifice from 2.5 mm (LT-condition) to 1.0 mm (ST-condition). During initial exposure to the ST condition, rate of licking was immediately enhanced but session intake was not regulated. Lick rate continued to increase across subsequent ST sessions and session intake similar to that during LT conditions was achieved after several ST sessions. However, volume regulation failed to occur during the first session following each transition from LT to ST conditions. Restrictions in the rate of consumption increased the duration but not the frequency of post-pellet licking bouts, and resulted in decreased rates of bar-pressing with enhanced pause time. Reinforcement frequency across conditions was unaffected. Increased licking rates during ST sessions also resulted in enhanced licking rates during sugsequent LT sessions. These results suggest that volume regulation during schedule-induced polydipsia is achieved through reductions in competing responses, and changes in both the discriminative control of drinking and topography of licking.