Dibenzcycloheptadienes: With Some Remarks on Their Relationship to Degradation Products of Colchicine

Abstract Not Provided

An Analysis of the Effect of Vibration Sensitivity on Hydrophone Design

Hydrophones used in the ocean produce spurious outputs due to vibration sensitivity which can severely degrade measurement accuracy. Sources of these vibration inputs are ocean surface waves, flow turbulence, and induced mechanical vibration. The hydrophone response to these vibrations is a noise voltage output. This can leave to a signal-to-noise problem particularly when measurements of small sound pressure levels are to be made. The objective of this thesis is to analyze the vibration response of three typical piezoelectric hydrophone sensor elements configurations and give design methods and constraints for reducing the problem of vibration sensitivity to an acceptable level. The sensor element configurations analyzed are the radially polarized cylindrical shell, radially polarized spherical shell, and axially polarized cylindrical shell. The analysis is carried out due to two causes. An electromechanical analysis is given of the voltage sensitivity of each of the three sensor configuration to the inertial effect of acceleration inputs. The second effect analyzed is the voltage sensitivity of a pressure sensitive sensor element to the hydrostatic pressure amplitude caused by periodic vertical displacement of a hydrophone. Results of the analyses show that the radially polarized cylindrical and spherical shell configurations have zero acceleration sensitivity to inputs on the axes analyzed. An equation is derived for the axial acceleration sensitivity of the axially polarized cylindrical shell in terms of the equivalent sound pressure. The analysis of hydrophone sensor response to periodic vertical displacements shows high voltage sensitivity to very small displacement amplitudes. Data is given for the maximum permissible vertical displacement amplitude to produce a 20dB signal-to-noise ratio. Based on these analyses, design considerations are given to minimize hydrophone vibration sensitivity

Landowners’ Perceptions and Involvement in the Management of Kyabobo National Park, Ghana

This study examines the perceptions of landowners of fringe communities of the Kyabobo National Park (KNP) about their involvement in the creation and management of the KNP. Four KNP-fringe communities namely: Shiare, Odomi, Gekorong, and Keri which are less than a kilometre from the boundary of the park were selected for the study. Pearson correlation coefficient was used to establish the relationship between landowners’ perceptions and their involvement in the management of the park. A systematic sampling method was used to select 212 landowners for interviews using a structured interview schedule. The study found that some landowners in the KNP-fringe communities were employed at various levels in the management of the park but were not managing partners of the park. Landowners also benefited from selling handicrafts to park visitors. The physical infrastructures in the communities have remained poor. It is recommended that landowners in park-fringe communities are given the opportunity to become managing partners of the park to guarantee the successful operation of the park. Government should also provide modern physical infrastructure in the KNP-fringe communities as was promised prior to the establishment of the park

Predictors of Medication Nonadherence Differ among Black and White Patients with Heart Failure

Heart failure (HF) is a global public health problem, and outcomes remain poor, especially among ethnic minority populations. Medication adherence can improve heart failure outcomes but is notoriously low. The purpose of this secondary analysis of data from a prospective cohort comparison study of adults with heart failure was to explore differences in predictors of medication nonadherence by racial group (Black vs. White) in 212 adults with heart failure. Adaptive modeling analytic methods were used to model HF patient medication nonadherence separately for Black (31.7%) and White (68.3%) participants in order to investigate differences between these two racial groups. Of the 63 Black participants, 33.3% had low medication adherence, compared to 27.5% of the 149 White participants. Among Blacks, 16 risk factors were related to adherence in bivariate analyses; four of these (more comorbidities, lower serum sodium, higher systolic blood pressure, and use of fewer activities compensating for forgetfulness) jointly predicted nonadherence. In the multiple risk factor model, the number of risk factors in Black patients ranged from 0 to 4, and 76.2% had at least one risk factor. The estimated odds ratio for medication nonadherence was increased 9.34 times with each additional risk factor. Among White participants, five risk factors were related to adherence in bivariate analyses; one of these (older age) explained the individual effects of the other four. Because Blacks with HF have different and more risk factors than Whites for low medication adherence, interventions are needed that address unique risk factors among Black patients with HF

Evaluation of Microcosms for Determining the Fate and Effect of Benz(a)anthracene in Aquatic Systems

Small scale, three-phase microcosms were used to study the aquatic fate and effect of a polycyclic aromatic hydrocarbon (PAH), benz(a)anthracene. This compound was chosen as a model for carcinogenic PAH because it is a typical constituent of petro-chemical effluents and has middle-of-the-range physical and chamical characteristics. In a series of experiments, techniques were established for monitoring the behavior and for assessing the biological response to the pollutant. Results indicate taht benz(a)anthracene has no acute effect on aquatic organisms as indicated by the parameters used to measure community structure and function (gas productivity, nutrient utilization, biomass accumulation, and species composition). Gas chromatograph/mass spectral analysis of benz(a)anthracene and metabolites in the medium sediment, and biota made it possible to trace the fate of the compound. At the end of one 60 day experiment, 76 percent remained in the sediment, 17 percent had been recovered in the medium, 1 percent was associated with the biota. Of the remaining 5 percent, a portion photodegraded. There was no evidence of metabolism

Effects of 4-lobe swirl-inducing pipe on pressure drop

This thesis describes the effects of the 4-lobe swirl-inducing pipe on pressure drops for water, sand-water slurry and carboxymethyl cellulose fluids. The pressure drops were measured for two 4-lobe swirl-inducing pipe combined, one 4-lobe swirl-inducing pipe and without swirl-inducing pipe. The swirling pipe applications were installed before a bend on radius-to-diameter (R/D) ratio of 4. The pressure drops were measured on three different locations, before and after the 4-lobe swirl-inducing pipe, and after the bend. Swirling flow behaviours were observed for sand-water slurry at different concentrations. Reynolds number indicated water and sand-water slurries in turbulent regimes. The sand particles were evenly distributed when induced with swirling flow, which caused less wear effect on a pipe-cross section. Results indicated that the swirl-inducing pipe increased the pressure drop for higher concentrations. The 4-lobe swirl-inducing pipe caused an increased in pressure drop over horizontal pipe and a reduction in pressure drop over the bend. Results showed that the overall pressure drops across pipe (after swirl and bend) were increased with swirl-inducing pipe

Studies on the physiology of lichens with special reference to Peltigera praetextata (Flk.) Vain

Part 1 comprises tm investigation of several lichens for fixation of elemental nitrogen. Three lichens, Collema gronosum (Scop.) Sehaer., leptogjum lichenoides (L.) Zahlbr., and Poltigera praetextate (Flk.) Vain., each containing blue-green algae, were examined by a technique using the heavy isotope of nitrogen., 15N All were shown to fix atmospheric nitrogen. Evidence is provided to show that the fixation should be attributed to the algal symbiont (Nostoe) of these lichens. In the case of Leptogium and calculation of the total fixation of nitrogen over a period of five days, shows that the rate of fixation ( approx. 0.05 mg. nitrogen per gm, fresh weight of lichen) was too high to he attributed to any nitrogen-fixing agent (e.g. Azotobacter) other than the Nostoe. Confirmation of the fixation of nitrogen by Peltigera praetextata was obtained by a study of the growth, in nitrogen- free mineral solution, of dises of this lichen. It is also shown, by this method of culture, that nitrogen fixed by the algal symbiont is transferred to the associated fungal hyphao. Application of the isotopic test to two lichens containing green algae, Cladonia imnexa Harm. F. laxiuseula (Del.) Sendst, and Lobaria nulmonaria (L.) Hoffm., gave no evidence of fixation of nitrogen, it is considered, on the basis of these tests, that the triple symbiosis theory of Henckel and Yuzhakova (1936) can not he universally applied to lichens. In Part II is described an investigation of the growth, in culture, of discs of poltigera praetextata. Experiments are described which relate to the effect, on growth of discs, of the concentration of nutrients in the culture medium, and of the moisture content of the discs. Data for the rate of growth, under greenhouse conditions, of an entire plant of this species are given. This is shown to be higher than the rate of growth of discs of the lichen in culture. A physiological investigation of the formation of isidia on p. praetextate, and on other species of the genus, leads to the view that these structures are initiated by a light stimulus acting on the algal symbiont. An isidioid growth, somowhat similar to that commonly found on P.praetextata, has been induced to form on P.horizontalis, a species on which these structures are not found in Nature. Considerable evidence is produced, both from culture work and from examination of herbarium material, to support the view that the isidia of P. praetextata are potential reproductive organs. The isolation of the algal symbiont of P. praetextata, in bacteria-free culture, is described in Part III. Three isolation techniques were used. The isolated alga was irradiated with ultra violet light to produce a bacteria-free culture. Various stages in the development of the algal symbiont in culture are described and Illustrated. The alga is shown to be capable of heterotrophic growth, with the continued, formation of chlorophyll, using glucose as the source of energy. Part if comprises an investigation of the characteristics of dissemination and germination of ascospores of Peltligera praetetata. An aqueous extract of Nostoc, isolated from P. praetextata alone provided a suitable medium for spore germination. A detailed investigation of the causes of spore rupture in various synthetic media and in media containing agar, showed that this effect was due to an excess of vitamins la these media, The addition of thiamin (100 gamma/1.) or biotin (10 gamma/1.), to vitamin-free media produced a similar effect. The advantages of silica-gal as a substitute for agar are discussed. Tabulation of the data recorded for 83 apothecia of Peltigera praetextata,, used in experiments over a period of three years, shows that spores arc ejected, from the apothecia throughout the year, At no season arc they incapable of germinating. Consideration of the data obtained regarding spore rupture leads to the view that a large percentage of spores ejected from apothecia to the soil surrounding the plant, must succumb to this effect and hence be unable to germinate. The continued use of the term "gonidia" in the description of lichen-algae is deprecated. The term "phycobiont" is proposed, to replace "gonidium" and synonymous terms such as "algal symbiont", "algal host" and "lichen-alga". The term "mycobiont" is proposed, to replace the terms "fungal symbient" and "lichen-fungus"