High blood pressure is associated with decreased sensitivity to pain in humans and animals. Interestingly, hypoalgesia has also been observed in normotensive organisms at risk for hypertension, suggesting that it may be related to processes involved in the development of hypertension rather than with elevations of blood pressure per se. Sensitivity to laboratory and naturalistic daily aches and pains was assessed in young normotensive women and men with or without a parental history of hypertension and varying degrees of resting blood pressure. In women, risk for hypertension, as defined by a parental history of hypertension, relatively elevated systolic blood pressure, or a combination of the two, was associated with decreased pain reports and increased pain threshold for mechanical finger pressure, but not for the cold pressor test. Offspring of hypertensives also exhibited a reduced response to the pain stimuli compared to offspring of normotensives as assessed by the objective physiological measure of respiratory sinus arrhythmia (RSA). Group differences observed in the laboratory were generally maintained in reports of daily pain, with significant correlations emerging between laboratory and naturalistic pain reports. To assess the role of cardiopulmonary baroreceptor stimulation in blood pressure-related hypoalgesia, young men varying in risk for hypertension were exposed to finger pressure during a period of passive leg elevation and two control periods. Men with relatively elevated systolic blood pressure exhibited reduced pain during the period of leg elevation but not while in a supine position, nor following the valsalva manoeuver. The results of these studies support an association between risk for hypertension and pain sensitivity. This relation appears to extend to naturalistic pain encountered in daily life. Further, there is promising evidence suggesting that this relationship is influenced by cardiopulmonary baroreceptor activity.

The low temperature spin dynamics of the canonical dipolar spin ice materials is examined. The ac susceptibility of dipolar spin ice materials Ho2Ti2O7 and Dy2Ti2O7 is measured to lower temperatures and frequencies than previous studies. This provides a probe of the dynamics of fractionalized magnetic excitations which have been found to exist and interact as monopole-like particles within the spin ice con guration. Low temperatures and low frequencies access the dilute monopole phase, and provide a valuable stress case scenario to theory which has been used to describe the system to date. The relaxation is found to be well described at the lowest temperatures by an Arrhenius law with single energy barrier for both Ho2Ti2O7 and Dy2Ti2O7, with similar barriers to relaxation, 10.7 K and 9.79 K respectively. It is also revealed to be distinctly different from predictions of the dipolar spin ice model, based upon simulations of both a Coulomb gas and dipolar spin ice on the pyrochlore lattice. These simulations, as well as calculations based on Debye-Huckel theory, do not see Arrhenius behaviour in our temperature range, and do not predict the rate at which dynamics freeze out. It is not currently understood what would be required in order to amend this. The implications for thermal methods of probing spin dynamics is discussed, as well as how this measurement impacts the magnetolyte theory of spin ice. Brief reports are presented in the appendices of specific heat measurements of three spin liquid candidates: Yb2Ti2O7, Tb2Ti2O7, and Pr2Hf2O7. In Yb2Ti2O7, measurements of three single crystals, two unique features, a broad anomaly at 195 mK and sharp peak at 265 mK, are found which seem to comprise elements of previous single crystal and polycrystalline measurements. These low temperature features do not correspond to changes in neutron scattering intensity at 400 mK. In Tb2Ti2O7, a second order transition is found, corresponding to the emergence of a mode in inelastic neutron scattering. Absence of an ordering transition in the suspected <111> antiferromagnet Pr2Hf2O7 is also shown, with specific heat measured down to 100 mK with no ordering transition.

A growing literature has reported a significant reduction in pain sensitivity among hypertensioe animals and humans. One of the key questions about this finding is whether a reduced sensitivity to pain can be observed in normotensive individuals who go on to develop high blood pressure. Blood pressure was re-assessed in one hundred and fifteen 19 year-old boys initially tested at age 14, when they were also presented with a pain stimulus (mechanical finger pressure). Analyses indicated that information regarding pain sensitivity improved prediction of changes in blood pressure beyond that afforded by differences in blood pressure at age 14, parental history of hypertension, and body mass index. Similar results were found in comparable analyses predicting 24-hour blood pressure recorded in one hundred and seventeen of the young men at age 22. Significant associations were also observed between pain sensitivity in 14 year-olds and 24-hour heart rate variability in various frequency bands at age 22, suggesting increased sympathetic and reduced parasympathetic tone among individuals less sensitive to pain. In order to further assess the relationship between autonomic function and pain sensitivity, one hundred and sixteen adolescent boys were assessed for pain sensitivity and autonomic responses to orthostatic challenge. Analyses indicated that exaggerated autonomic responses to postural change were associated with reduced pain sensitivity. Finally, to examine the potential role of endogenous opioids in blood pressure-related hypoalgesia, a group of young normotensive men were administered low-frequency transcutaneous electrical nerve 5 stimulation (TENS), which has been demonstrated to elicit endogenous opioid release, prior to being presented with two painful stimuli (electric shock and arm ischemia). A negative association between pain and resting blood pressure was significantly strengthened by administration of low-frequency TENS. The resu

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains viii, 152 p. : ill. (some col.), maps. Includes abstract. Includes bibliographical references (p. 62-64).

The British Tertiary Volcanic Province comprises central volcanic complexes with positive gravity and magnetic anomalies, some centres associated with both large volumes of continental flood basalts and regional dyke swarms. The Lundy Island is the southern most expression of Tertiary volcanism and consists of granite intruded by around 200 dykes and associated with positive gravity and magnetic anomalies. The Lundy Dyke Swarm comprises basalt/dolerite and trachyte to rhyolite intrusions within host Tertiary granite (58.7 ± 1.6 Ma) and Devonian sediments. Outcrops of dykes are confined to coastal exposures on Lundy as they are veneered by peat over most of the island. Dykes present paired magnetic anomaly profiles, which allows their trends tobe determined by proton magnetometry. The dykes have a radial disposition superimposed on a ENE-WSW regional trend. Anisotropy of magnetic susceptibility studies indicate that magma for the radial component was emplaced at shallow to moderate inclinations, suggesting a relatively shallow origin near to the western border of Lundy Island. The regional component was emplaced at shallow to sub-horizontalangles, suggesting lateral movement of magma from a possible source 12 km to the northwest. Geochemical signatures indicate that the Lundy Dyke Swarm was transitional between plume-related magmatism and partial melting of the lithospheric mantle, the magma being stored in several small storage bodies at differing depths in the upper continental crust, rather than in one large magma chamber. Basic dykes at Lee Bay (60 ± 0.6 to 63.1 ± 0.7 Ma) pre-date the Lundy Dyke Swarm and were derived from a discrete magma chamber, possibly near to Morte Point. Conversely, other dykes in North Devon (Fremington dyke - 292.4 ± 1.7 Ma; Horse-Shoe Rocks - 339.6 ± 7.4 Ma) are not directly related to Tertiary magmatism, even though the Horse-Shoe Rocks have a Tertiary palaeomagnetic overprint. The Lundy Igneous Complex (comprising granite, dykes and sub-surface basic rocks) is situated close to the intersection of the Variscan Front and the Welsh Caledonides massif where the continental thickness is between 25 and 27 km. Emplacement of magma was assisted by the heavily fractured nature of the host sediments. However, a large positive gravity anomaly to the northwest of Lundy Island does not have a corresponding magnetic anomaly and so is interpreted as the response to relatively dense uplifted basement in the Lundy Horst rather than a large volume of basic rocks. Thus, the Lundy Igneous Complex probably did not produce sub-aerial volcanic activity, as pressure in the magma chamber would not have exceeded the overlying litho static load, despite the fractured nature of the host rocks.

Although Autism Spectrum Disorders (ASD) are often characterized by deficits in social domains, increasing evidence suggests that individuals with ASD have perceptual biases associated with a shift from reliance on global to local visual cues. This dissertation provides evidence for a two-factor structure to the systemizing trait of autism, as measured by the Systemizing Quotient-Revised (SQ-R), which differentially predicts this perceptual shift in the general population. Specifically, an Analytical Tendencies factor within the SQ-R was found to predict attenuated susceptibility to the global contextual cues that drive the rod-and-frame illusion (RFI), while an Insistence on Sameness factor was associated with heightened sensitivity to the local cues that drive the RFI. Furthermore, in a clinical sample of individuals with ASD, both Analytical Tendencies and Insistence on Sameness factors were found to be hyper-expressed, suggesting that perceptual biases in ASD populations can be explained, in part, by heightened systemizing tendencies. In addition, the Analytical Tendencies factor was also found to predict enhanced performance on the Embedded Figures Task, a visual search task commonly used to assess perceptual abilities in ASD. Furthermore, enhanced performance on this task was associated with reduced susceptibility to the global contextual effects of the RFI, suggesting that superior search performance in individuals with ASD may be due, in part, to attenuated interference from the contextual gestalt of the search array. Importantly, the relationship between heightened systemizing tendencies and attenuated use of global contextual cues was found to reflect a disinclination among high systemizers to use such cues and not a general impairment in processing such cues. Specifically, when contextual cues that benefit performance are available, high systemizers can use these cues to the same extent as low systemizers. Together, these findings implicate a two-factor structure to the SQ-R that is differentially predictive of distinct types of visual processing associated with ASD.

Microbicides are used in consumer products worldwide to enhance their antibacterial potency in disinfection, for antisepsis or as preservatives. With the widespread use of these compounds, concerns have been expressed about their potential to select for reduced susceptibility. Whilst in vitro studies have reported the laboratory generation of bacterial insusceptibility for certain combinations of bacterium and microbicide, true microbicide resistance, which is defined as a change in susceptibility that is likely to affect the outcome of treatment, has not been frequently reported or observed in the environment. Importantly, risk assessments on the use of microbicides have been largely based on laboratory studies whereby pure cultures of bacteria are exposed to microbicides in aqueous solution. In use however, microbicides are formulated with various excipients and bacteria are exposed to them most commonly in complex biofilm communities. Work described in this doctoral thesis evaluates the effects of exposing bacteria to microbicides using exposure conditions intended to increase realism, with the ultimate aim of informing improved risk assessment methods that better reflect deployment of microbicides in the real-world, taking in to account the effects of formulation, growth in multi-species communities and potential reduced competiveness in adapted bacteria. Test bacteria (8 species, 7 genera) were repeatedly exposed to selected microbicides in aqueous solution and in various formulations reflecting their use in the domestic environment, such as general-purpose cleaners and laundry detergents. Minimum inhibitory concentrations, minimum bactericidal concentrations and minimum biofilm eradication concentrations were determined before and after 14 passages (P14) in the presence of microbicides (benzalkonium chloride (BAC), benzisothiazolinone (BIT), chlorhexidine (CHX), didecyldimethyl ammonium chloride (DDAC), Glydant (DMDM-hydantoin), polyhexamethylene biguanide (PHMB), thymol and triclosan) in aqueous solution or in formulation, using a previously validated gradient plating system. Bacteria were subsequently passaged a further 14 times in the absence of any antimicrobial agent to determine the stability of any adaptations (X14). In bacterial isolates that demonstrated marked changes in susceptibility, further phenotypic analysis was conducted to test for any induced alterations in antibiotic susceptibility, planktonic growth rate, biofilm formation, competitive fitness and relative pathogenicity. Exposure of microbial communities was carried out using a previously validated domestic drain biofilm simulator within constant depth film fermenters (CDFF). The CDFFs were exposed to increasing concentrations of BAC in aqueous solution or BAC formulation over a 32-week period. Changes in bacterial community composition and antimicrobial susceptibility distributions were assessed via replica plating onto selective and antimicrobial-containing agars as well as through the use of next generation sequencing technologies via the illumina Miseq platform and QIIME software. The formulation of microbicides significantly increased antibacterial and anti-biofilm potency and reduced the incidence and extent of the development of insusceptibility isolated bacteria (7 non-revertible bacteria in MBCs for microbicides, whilst 2 non-revertible bacteria in MBCs for formulations). In bacteria that develop marked changes in antimicrobial susceptibility after repeated exposure show changes to biofilm growth rates (10 increases and 6 decreases after microbicide exposure; 1 increase and 3 decreases after formulation exposure), as well as alterations in competitive fitness (6 decreases and 19 increases after microbicide exposure; whilst all exposed to formulation had decreased fitness) and virulence (9/13 decreased and 1/13 increased after microbicide exposure; 4/7 decreased and 2/7 increased after formulation exposure). In the multispecies microcosm system, long-term exposure to BAC or BAC formulation induced shifts in bacterial community dynamics and resulted in a decrease in BAC and various antibiotic susceptibilities (1 log10 reduction in the BAC system; 2.5 log10 reduction in the BAC formulation system of viable bacteria). Such shifts in community dynamics after antimicrobial treatment are theorised to be mainly due to clonal expansion of innately insusceptible bacteria (abundance of Achromobacter sp. increased by 39% in BAC system and 10% in BAC formulation system). Understanding the potential selectivity of microbicide-containing formulations is likely to better serve by testing formulations as well as actives in aqueous solutions. This highlights the need to conduct risk assessments of induced microbicide susceptibility changes using conditions that more accurately reflect their deployment.

No description available.

No description available.

In this thesis the result x-ray diffraction, magnetic susceptibility, magnetization, and Mössbauer spectroscopy measurements of EuPdGe3, Al13Fe4, and FeNiSn are reported. The compound EuPdGe3 crystallizes in the BaNiSn3-type tetragonal structure (space group I4mm) with the lattice constants a = 4.4457(1) Å and c = 10.1703(2) Å. The results are consistent with EuPdGe3 being an antiferromagnet with the Néel temperature TN = 12.16(1) K and with the Eu spins S = 7/2 in the ab plane. The temperature dependence of the magnetic susceptibility above TN follows the modified Curie-Weiss law with the effective magnetic moment of 7.82(1) 𝜇𝐵 per Eu atom and the paramagnetic Curie temperature of −5.3(1) K indicative of dominant antiferromagnetic interactions. The M(H) isotherms for temperatures approaching TN from above are indicative of dynamical short-range antiferromagnetic ordering in the sample. The temperature dependence of the hyperfine magnetic field follows a S = 7/2 Brillouin function. The principal component of the electric field gradient tensor is shown to increase with decreasing temperature and is well described by a 𝑇32⁄ power-law relation. The Debye temperature of EuPdGe3 determined from the Mössbauer data is 199(2) K. The compound Al13Fe4 crystallizes in the monoclinic space group C2/m, in which Fe atoms are located at five inequivalent crystallographic sites, with the lattice parameters a = 15.503(2) Å, b = 8.063(2) Å, c = 12.464(2) Å, and β = 107.71(2)°. It is demonstrated that zero-field Mössbauer spectra can be decomposed into three quadrupole doublets. With the aid of the calculated electric field gradient (EFG) parameters we show that the first doublet results from one Fe site, the second doublet is due to two other Fe sites, and the third doublet originates from the last two Fe sites. We find that the shape of the Mössbauer spectrum of Al13Fe4 measured in an external magnetic field of 90 kOe can be accounted for with five component subspectra generated using the calculated II EFG parameters at five inequivalent Fe sites. The quadrupole splittings corresponding to three component doublets are shown to increase with decreasing temperature and are well described by a 𝑇32⁄ power-law relation. The Debye temperature of Al13Fe4 is found to be 383(3) K. We find a pseudogap in the density of states (DOS), with a width of ∼ 0.2 eV, that is centered 0.1 eV above the Fermi energy. The finite DOS at the Fermi energy confirms good metallicity of Al13Fe4. The 1/T-like dependence of the magnetic susceptibility shows that Al13Fe4 is a paramagnet. The compound FeNiSn crystallizes in the ZrBeSi-type crystal structure (space group P63/mmc) with the lattice constants a = 4.1329(1) Å and c = 5.1912(2) Å. It is a ferromagnet with the Curie temperature TC = 1024(10) K. Evidence is provided for a possible phase separation in the studied compound, into a majority magnetic phase and a minority, nanoscale, disordered phase with the corresponding iron magnetic moments at 4.6 K of 2.39(1) and 1.17(1) 𝜇𝐵. It is demonstrated that FeNiSn decomposes at a temperature significantly below TC when it is annealed in vacuum for about 30 hours. The Debye temperature of FeNiSn is found to be 445(6) K.