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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
491

Active Flutter Suppression Of A Smart Fin

Karadal, Fatih Mutlu 01 September 2008 (has links) (PDF)
This study presents the theoretical analysis of an active flutter suppression methodology applied to a smart fin. The smart fin consists of a cantilever aluminum plate-like structure with surface bonded piezoelectric (PZT, Lead- Zirconate-Titanate) patches. A thermal analogy method for the purpose of modeling of piezoelectric actuators in MSC&reg / /NASTRAN based on the analogy between thermal strains and piezoelectric strains was presented. The results obtained by the thermal analogy were compared with the reference results and very good agreement was observed. The unsteady aerodynamic loads acting on the structure were calculated by using a linear two-dimensional Doublet-Lattice Method available in MSC&reg / /NASTRAN. These aerodynamic loads were approximated as rational functions of the Laplace variable by using one of the aerodynamic approximation schemes, Roger&amp / #8217 / s approximation, with least-squares method. These approximated aerodynamic loads together with the structural matrices obtained by the finite element method were used to develop the aeroelastic equations of motion of the smart fin in state-space form. The Hinf robust controllers were then designed for the state-space aeroelastic model of the smart fin by considering both SISO (Single-Input Single-Output) and MIMO (Multi-Input Multi-Output) system models. The verification studies of the controllers showed satisfactory flutter suppression performance around the flutter point and a significant improvement in the flutter speed of the smart fin was also observed.
492

Performance Evaluation Of Piezoelectric Sensor/actuator On Investigation Of Vibration Characteristics And Active Vibration Control Of A Smart Beam

Aridogan, Mustafa Ugur 01 June 2010 (has links) (PDF)
In this thesis, the performance of piezoelectric patches on investigation of vibration characteristics and active vibration control of a smart beam is presented. The smart beam is composed of eight surface-bonded piezoelectric patches symmetrically located on each side of a cantilever aluminium beam. At first, vibration characteristics of the smart beam is investigated by employment of piezoelectric patches as sensors and actuators. Smart beam is excited by either impact hammer or piezoelectric patch and the response of the smart beam particular to these excitations is measured by piezoelectric patches used as sensors. In order to investigate the performance of piezoelectric patches in sensing, the measurements are also conducted by commercially available sensing devices. Secondly, active vibration suppression of the smart beam via piezoelectric sensor/actuator pair is considered. For this purpose, system identification of the smart beam is conducted by using four piezoelectric patches as actuators and another piezoelectric patch as a sensor. The designed robust controller is experimentally implemented and active vibration suppression of the free and first resonance forced vibration is presented. Thirdly, active vibration control of the smart beam is studied by employment of piezoelectric patches as self-sensing actuators. Following the same approach used in the piezoelectric sensor/actuator pair case, system identification is conducted via self-sensing piezoelectric actuators and robust controller is designed for active vibration suppression of the smart beam. Finally, active vibration suppression via self-sensing piezoelectric actuators is experimentally presented.
493

Unerwünschte Gedanken bei Angststörungen / Diagnostik und experimentelle Befunde

Fehm, Lydia Birgit 25 June 2000 (has links) (PDF)
Die vorliegende Arbeit beschäftigt sich mit der Diagnostik unerwünschter Gedanken sowie der Spezifität von Gedankenunterdrückung bei phobischen Patienten. Zwei Fragebogenverfahren zum Thema Sorgen sowie ein Instrument zur Erfassung von Strategien im Umgang mit intrusiven Gedanken wurden bezüglich der Gütekriterien der deutschen Übersetzung in einer klinischen Stichprobe evaluiert. Dabei handelt es sich um den Worry Domains Questionnaire (WDQ), der Sorgeninhalte erhebt, den Penn State Worry Questionnaire (PSWQ), der die Intensität von Sorgen erfasst, und den Thought Control Questionnaire (TCQ) zur Erfassung der Gedankenkontrollstrategien. Die Verfahren wurden bei 440 Psychotherapie-Patienten zu drei Meßzeitpunkten eingesetzt. Hinsichtlich der inneren Konsistenz und der Retest-Reliabilität ergeben sich für alle Instrumente zufriedenstellende bis gute Kennwerte. Die Validität ist nur für den PSWQ als gut zu bezeichnen. Beim WDQ zeigen sich Probleme hinsichtlich der Trennung von Sorgen und sozialer Ängstlichkeit, während der TCQ wohl eher Aspekte allgemeiner Psychopathologie als spezifische Strategien erfasst. Eine zweite Studie befasste sich mit intentionaler Gedankenunterdrückung. Die paradoxen Effekte dieser Bemühungen wurden wiederholt mit psychischen Störungen, vor allem mit Angststörungen, in Verbindung gebracht. Dabei ist ein wichtiges Thema, ob die Gedankenkontrollfähigkeit nur für störungsspezifische Inhalte oder generell beeinträchtigt ist. Die vorliegende Studie verglich Patienten mit Agoraphobie und Patienten mit Sozialphobie mit einer gesunden Kontrollgruppe. Alle Personen mussten Gedanken an ein neutrales Kontrollthema sowie zwei störungsspezifische Themen unterdrücken. Es zeigte sich ein störungsspezifischer Effekt bei den Agoraphobikern. Sozialphobiker scheinen hingegen ein generelles Defizit ihrer mentalen Kontrolle aufzuweisen. Zusätzlich erwies sich soziale Ängstlickeit innerhalb einer Reihe psychopathologischer Variablen als stärkster Prädikator für Schwierigkeiten bei der Gedankenunterdrückung. Ingesamt weisen einige Ergebnisse dieser Arbeit darauf hin, dass Gedankenunterdrückung ein wichtiges Merkmal der Sozialphobie sein könnte. / The work conducted aimed at evaluating instruments investigating unwanted thoughts as well as determining the specifity of thought suppression in phobia. German translations of two questionnaires measuring worry as well as an instrument, measuring strategies used in dealing with unwanted thoughts, were evaluated in a clinical sample. We used the Worry Domains Questionnaire (WDQ), measuring contents of worry, the Penn State Worry Questionnaire (PSWQ), measuring the intensity of worry, and the Thought Control Questionnaire (TCQ), investigating strategies in thought control. The instruments were administered at three points in a sample of 440 patients receiving psychological treatment. Concerning internal consistency and retest-reliability all questionnaires showed acceptable to good results. Validity is only good concerning PSWQ. WDQ has problems in differentiating worry and social anxiety, where as TCQ seems to measure general psychopathology more than specific strategies. The second study investigated intended thought suppression. Its paradoxical effects have been linked to psychological disorders, namely anxiety disorders. One important issue is if thought suppression is impaired only for thoughts related to the disorder or if the ability for mental control is generally impaired in anxiety patients. This study compared groups of agoraphobics and social phobics with healthy controls. All subjects had to suppress a neutral topic and two topics related to the central fear of the two disorders. We found a rather specific deficit in thought suppression for the agoraphobics. Social phobics seem to be characterized by a general impairment of mental control. In addition, among several psychopathological variables, social anxiety proved to be the strongest predictor for problems with thought suppression. Taken together, there are several indicators that thought suppression may be an important feature of social phobia.
494

Development of PYRAMDS (Python for Radioisotope Analysis and Multi-Detector Suppression) code used in fission product detection limit improvements with the DGF Pixie-4 digital spectrometer

Weaver, Christopher Jordan 06 July 2011 (has links)
The work presented here develops a gamma-ray spectral construction and analysis software tool that was used to analyze multi-detector data collected using a digital spectrometer with list mode capabilities. The tool was used to parse the output from three detectors and generate new spectra that the user chooses from post-processing suppression routines, such as simulated anticoincidence and coincidence spectra. Part of this research was also to characterize the improvements in the detection limits and the various detector efficiencies from this method as opposed to creating these spectra using traditional electronic gating systems. A focus is placed on the detection capability improvements for nuclear forensics purposes, particularly the identification and quantification of fission product samples, and structuring the code framework for handling these types of time-dependent samples while increasing the versatility of the detector system. Improvements to the minimum detectable activity for a series of fission products was accomplished through post-processing suppression methods and multi-dimensional spectral data structures are now achievable. / text
495

Identification of the radionuclides in spent nuclear fuel that may be detected by Compton suppression and gamma-gamma coincidence methods

Schreiber, Samuel Stuart 01 August 2011 (has links)
The nuclides present in spent nuclear fuel are categorized according to their capacity for detection by Compton suppression or gamma-gamma coincidence methods. The fifty nuclides with the highest activities in spent fuel are identified, their decay schemes analyzed, and the best detection scheme for each is recommended. / text
496

Compost Water Extracts And Suppression Of Root Rot (F. Solani F. Sp. Pisi) In Pea: Factors Of Suppression And A Potential New Mechanism

Tollefson, Stacy Joy January 2014 (has links)
One of the motivating reasons for the development of hydroponics was avoidance of root pathogens. Hydroponics involves growing crops in relatively sterile media, isolated from the underlying soil which may have disease pressure. However, even when hydroponics is coupled with controlled environments such as high tunnels and climate-controlled greenhouses, soil-borne pathogens can enter the growing area and proliferate due to optimal environmental conditions for pathogen growth. Control of root pathogens is difficult and usually achieved through synthetic fungicides since few biocontrol options are available. Compost water extracts (CWE) have recently been gaining the attention of greenhouse growers because they may be a low-cost, environmentally friendly approach to control root disease. CWE are mixtures of compost and water incubated for a defined period of time, either with or without aeration, and with or without additives intended to increase microbial populations, which in turn suppress disease. Much anecdotal, but very little scientific, evidence exists describing CWE effect on suppressing soil-borne pathogens. The present study 1) examined the effect of an aerated CWE on disease suppression at the laboratory scale and in container studies using different soilless substrates, 2) investigated a phenotypic change at the root level caused by CWE that may be associated with disease suppression, and 3) isolated some factors in the production of CWE that affect the ability of a CWE to suppress disease. The common model pathogen-host system of Fusarium solani f.sp. pisi and pea was used to examine CWE-induced disease suppression, with information then being translatable to similar patho-systems involved in greenhouse crop production. In the first study, laboratory-based root growth and infection assays resulted in 100% suppression of F. solani when roots were drenched in CWE. These protected seedlings were then taken to a greenhouse and transplanted into fine coconut coir, watered with hydroponic nutrient solution, and grown for five weeks. At the end of the experiment, 23% of the shoots of the pathogen-inoculated, CWE-drenched seedlings remained healthy while only 2% of the inoculated seedlings without CWE drench remained healthy. All of the roots of the inoculated seedlings developed lesions, even those drenched in CWE. However, 29% of the CWE drenched roots were able to recover from disease, growing white healthy roots past the lesion, while only 2% recovered naturally. A shorter-term container study was conducted in the laboratory to determine the effects of CWE-induced suppression when peas were grown in different substrates and to determine if the hydroponic nutrient solution had an effect on the suppression. Peas were grown in sterilized fine and coarse coconut coir fiber and sand irrigated with water, with a second set of fine coir irrigated with hydroponic nutrient solution. Pea seeds with 20-25mm radicles were inoculated with pathogen and sown directly into CWE-drenched substrate and grown for three weeks. At the end of the experiment, 80%, 60%, 90%, and 50% of the shoots of the inoculated, CWE-drenched seedlings remained healthy when grown in fine coir, coarse coir, sand, and fine coir irrigated with hydroponic nutrient solution, respectively. Nearly 100% of the roots grown in coconut coir substrates again developed necrotic lesions but 83%, 87%, 100%, and 87% grew healthy roots beyond the disease region. The hydroponic nutrient solution had a negative effect on suppression, with a reduction of at least 30 percentage points. Sand demonstrated a natural ability to suppress F. solani. Only 23% of inoculated seedlings had dead or dying shoots by the end of the experiment (compared to 77-80% in coir substrates) and although all but one of the roots developed lesions, all were able to recover on their own with CWE. CWE further increased shoot health and also prevented 57% of the roots from developing lesions. In a second study, two different CWE were used to examine the effect on root border cell dispersion and dynamics in pea, maize, cotton, and cucumber and its relation to disease suppression. Dispersal of border cells after immersion of roots into water or CWE was measured by direct observation over time using a compound microscope and stereoscope. Pictures were taken and the number of border cells released into suspension were enumerated by counting the total number of cells in aliquots taken from the suspension. Border cells formed a mass surrounding root tips within seconds after exposure to water, and most cells dispersed into suspension spontaneously. In CWE, >90% of the border cell population instead remained appressed to the root surface, even after vigorous agitation. This altered border cell phenomena was consistent for pea, maize, and cotton and for both CWE tested. For most cucumber roots (n=86/95), inhibition of border cell dispersal in both CWE was similar to that observed in pea, maize, and cotton. However, some individual cucumber roots (8±5%) exhibited a distinct phenotype. For example, border cells of one root immersed into CWE remained tightly adhered to the root tip even after 30 minutes while border cells of another root immersed at the same time in the same sample of CWE expanded significantly within 5 minutes and continued to expand over time. In a previous study, sheath development over time in growth pouches also was distinct in cucumber compared with pea, with detachment of the sheaths over time, and root infection was reduced by only 38% in cucumber compared with 100% protection in pea (Curlango-Rivera et al. 2013). Further research is needed to evaluate whether this difference in retention of border cell sheaths plays a role in the observed difference in inhibition of root infection. In the third study, a series of investigations were conducted to isolate different factors that contribute to the suppression ability of a CWE by changing incrementally changing some aspect of the CWE production process. The basic aerated CWE recipe (with molasses, kelp, humic acid, rock phosphate, and silica) provided 100% protection of pea from root disease while the non-aerated basic recipe CWE provided 72% protection. Aerated CWE made of only compost and water resulted in 58% protection. It was found that molasses did not contribute to the suppression ability of the ACWE, while kelp contributed strongly. When soluble kelp was added by itself to the compost and water, the CWE provided 80% suppression. However, when all additives were included except molasses and kelp, suppression remained high (93%) indicating that humic acids, rock phosphate, and/or silica were also major contributors toward the suppression effect. Optimal fermentation time for ACWE was 24 hr to achieve 100% suppression, with increased time resulting in inconsistent suppression results. Optimal fermentation time for NCWE was 3 days or 8 days. These studies are important contributions to understanding the differences that might be expected in CWE suppression when growing in different substrates, some of the factors in the production of CWE that affects the ability of a CWE to suppress disease, and the phenotypic effect CWE has on the root zone of plants and the possible relationship between that effect and disease suppression.
497

Aplinkos triukšmo ir jo mažinimo, taikant lengvas konstrukcijas, tyrimai bei skaitinis modeliavimas / Research and Digital Modelling of Environmental Noise and its Reduction by Applying Light Structures

Grubliauskas, Raimondas 13 July 2009 (has links)
Disertacijoje nagrinėjamas triukšmo šaltinių keliamo triukšmo sklidimas į aplinką bei ieškoma mažinimo priemonių jam slopinti. Disertacijos tikslas – įver-tinti stacionarių ir mobilių šaltinių keliamo triukšmo sklaidą aplinkoje ir numatyti efektyvias priemones jai mažinti, naudojant triukšmo slopinimo kamerą, o prie-monių efektyvumą įvertinti modeliuojant. Šiame darbe sprendžiami keli pagrindiniai uždaviniai: sukurti ir įrengti triukšmo slopinimo kamerą; nustatyti triukšmo sklaidą, esant skirtingiems mobi-liems ir stacionariems triukšmo šaltiniams; numatyti bei modeliavimo būdu įver-tinti priemones triukšmui slopinti. Disertaciją sudaro įvadas, penki skyriai, rezultatų apibendrinimas, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai. Įvadiniame skyriuje aptariama tiriamoji problema, darbo aktualumas, apra-šomas tyrimų objektas, formuluojamas darbo tikslas bei uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai. Įvado pabaigoje pristatomos disertacijos tema autoriaus pa-skelbtos publikacijos ir pranešimai konferencijose bei disertacijos struktūra. Pirmasis skyrius skirtas literatūros apžvalgai. Jame išnagrinėti skirtingi triukšmo parametrai, jo šaltiniai, triukšmo mažinimo būdai, poveikis aplinkai, triukšmo sklaidos modeliavimo programos bei medžiagų akustinių savybių tyri-mai. Skyriaus pabaigoje formuluojamos išvados. Antrajame skyriuje pateiktos eksperimentinių tyrimų, skirtingų šaltinių... [toliau žr. visą tekstą] / The dissertation analyses the problem of environment noise pollution and mitigation. The dissertation is aimed to evaluate the dispersion of noise from sta-tionary and mobile sources, provide for effective techniques and measures to re-duce it by using a noise suppression chamber for research into acoustic properties and to estimate the efficiency of the noise reduction measures through modelling. The work deals with main tasks: to design and fit out a noise suppression chamber and use it for research into the noise absorption and insulation proper-ties of different materials; to determine the levels and dispersion of noise from different mobile and stationary sources of noise; to determine the longitudinal sound wave attenuation coefficient for individual building materials and for buil-ding structures - the airborne sound attenuation index; to estimate the efficiency of the measures reducing noise from diferent sources with software “CadnaA”. The scientific work consist of the general characteristic of the dissertation, 5 chapters, conclusions and recommendations, list of literature, list of publications. The introduction discusses the problem addressed, topicality of the work, describes the object of research, and formulates the aim and tasks of the work, scientific novelty of the work, practical value of the research results and defen-ded propositions. It presents the author’s publications and conference reports on the topic of the dissertation and the structure of the... [to full text]
498

Discourse processing abilities in ageing : influence of working memory capacity on reference resolution.

Ghaleh, Maryam January 2015 (has links)
Maintaining health and quality of life into old age is a critical issue facing society today. Language, and in particular language comprehension, is vulnerable to the processes of ageing (Au, Albert, & Obler, 1989; Kynette & Kemper, 1986; Nicholas, Obler, Albert, & Goodglass, 1985; Shewan & Henderson, 1988). An improved understanding of language processing and ageing will assist in distinguishing language difficulties in normal ageing from those in pathological ageing and aphasia (Maxim & Bryan, 1994) and, potentially, optimises communication throughout life. The current thesis focuses on a specific component of language comprehension - anaphora resolution . Anaphora resolution occurs frequently in everyday discourse and has been reported to decline with ageing (Cohen, 1979; Light & Capps, 1986; Ulatowska, Hayashi, Cannito, & Fleming, 1986). This thesis explored anaphora resolution relative to two key variables: ageing and working memory. Ageing was chosen as a variable as anaphora resolution has been shown to be affected by age (Cohen, 1979; Light & Capps, 1986; Ulatowska et al., 1986). Working memory was chosen as working memory is thought to underlie key aspects of discourse comprehension such as building a mental structure of discourse and updating the information (Brébion, 2003; Hasher & Zacks, 1988; Radvansky, Copeland, & Hippel, 2010; Radvansky, Lynchard, & von Hippel, 2009). Anaphora resolution was investigated using two key paradigms. The first focussed on anaphora resolution in a reading comprehension task. Performance was assessed using accuracy of response. The second employed Gernsbacher's (1989) probe-response paradigm. The probe- response paradigm allowed examination of specific working memory processes underlying discourse comprehension, namely; a) storing and maintaining information in working memory (i.e., laying the foundation of the discourse structure); and b) updating information stored in working memory through suppressing the irrelevant discourse information. Storage and maintenance of the information was assessed by examining whether participants utilised “advantage of first mention” (Gernsbacher, 1990). Suppression was evaluated by investigating whether the accessibility of nonreferent names decreased in participants' working memory after they read anaphoric pronouns in sentences. This approach aimed to answer the following questions: 1) Do age and working memory capacity affect anaphora resolution in a comprehension task?; 2) Do age and working memory affect advantage of first mention in a probe recognition task?; and 3) Does age affect suppression of irrelevant information in an anaphora resolution task? In Chapter 3, Gernsbacher's (1989) original study was replicated. In Chapter 4 the same questions were examined, with the addition of a higher working memory load. For both studies, 30 younger and 30 older participants completed two comprehension experiments followed by an assessment of working memory capacity (reading span task). The comprehension experiments each contained a reading comprehension task and a probe recognition task. The reading comprehension task introduced two discourse characters (either a male or female name), one of which was referred to later in the text, using an anaphoric pronoun. Comprehension questions always asked about the referents of the anaphoric pronouns. Participants' accuracy in answering each comprehension question was indicative of their ability to resolve anaphora. Response times in the recognition task provided measures of the accessibility of: a) first and second mentioned names, and b) referent and nonreferent names. Chapters 3 and 4 found that, regardless of the tasks' working memory storage demands, older adults were less accurate than younger adults in the comprehension of anaphoric pronouns. Comprehension accuracy was related to working memory capacity, such that individuals with higher working memory capacity exhibited higher accuracy of response in the comprehension task. In addition, working memory capacity affected the accessibility of first and second mentioned names in the discourse suggesting that working memory capacity might influence the process of laying the foundation for the mental representation of comprehension. An ageing effect was observed on the suppression process during anaphora resolution under high working memory load only. When working memory load was low, neither younger nor older participants suppressed the accessibility of the nonreferents by the time they finished reading the sentences. This suggested that anaphora resolution might be postponed in less demanding tasks. However, under higher working memory load, younger adults, but not older adults, suppressed the accessibility of the nonreferents by the time they finished reading the sentence. It was therefore suggested that age-related changes in anaphora resolution abilities might be mediated by a decline in inhibitory functions that are responsible for suppressing the already-activated information that are no longer relevant to the task goals. The final study of the thesis (Chapter 5) aimed to determine why younger adults delayed the process of anaphora resolution in Experiment 1 (See Chapter 3), but completed the process by the time they finished reading the sentences in Experiment 2 (See Chapter 4). Specific questions addressed were: 1) Was comprehension accuracy affected by working memory storage load and the syntactic structure of the sentences?; 2) Do younger adults suppress the accessibility of the nonreferents by the time they reach the end of the sentence, in simpler sentences with increased storage load and late disambiguation?; and, 3) Do younger adults suppress the accessibility of nonreferents by the time they reach the end of the sentence, in more syntactically complex sentences with low storage load and prior disambiguation?. Forty younger participants completed four separate comprehension experimental tasks followed by a reading span test. A similar experimental approach was employed to that described in Chapters 3 and 4; however working memory storage load, syntactic complexity, and time-course for providing contextual information were manipulated. Results of Chapter 5 found that participants' accuracy declined in more syntactically complex sentences. A decline in accuracy appeared indicative of the tasks' higher processing demands and demonstrated that prior disambiguation was not facilitating the resolution of anaphora. Results from the recognition task showed that in sentences of increased syntactic complexity, participants suppressed the accessibility of nonreferents by the time they finished reading the sentence. It was suggested that higher processing demands of syntactically complex sentences, rather than a facilitating effect of earlier disambiguation in these sentences, contributed to the earlier suppression of nonreferents. In summary, this thesis demonstrated that older adults were less accurate than younger adults in comprehending anaphoric pronouns. Moreover, working memory capacity positively influenced comprehension accuracy and affected the advantage of first mention of discourse entities. It was suggested that individual differences in working memory capacity might affect the ability to lay foundations for discourse comprehension. Furthermore, older adults showed no suppression of nonreferents during processing of anaphora, regardless of working memory storage load. It appears possible that older adults' difficulty in anaphora resolution might be due to an inability to suppress irrelevant discourse information. Findings from the present study suggest that ageing may negatively affect the comprehension of linguistic structures for which more than one meaning could be inferred. While further exploration of this finding is required, it is possible that communication strategies could be devised to minimise the use of structures with more than one meaning - with the aim of improving and maintaining communication in older adults. Ultimately, determining the underlying causes of language impairments in both healthy ageing and neurological disease will help to improve speech-language therapy methods for these populations.
499

Animal and Pasture Responses to Grazing Management of Chemically Suppressed Tall Fescue in Mixed Pastures

Williamson, Jessica A 01 January 2015 (has links)
Treatment of endophyte-infected tall fescue [Lolium arundinaceum (Schreb.) Darbysh] with the broad leaf herbicide Chaparral® can mitigate fescue toxicosis and enhance forage quality by suppressing seedhead emergence. Applying the herbicide to fescue pastures also reduces forage mass and promotes severe spot grazing when pastures are continuously grazed. A grazing experiment was conducted with steers (2013) and heifers (2014) to evaluate animal and plant responses in fescue-bluegrass (Poa pratensis L.) mixtures treated with Chaparral to determine the effects of grazing management on pasture carrying capacity, nutritive values, botanical composition, and animal performance. Continuous and rotational (i.e., four subdivisions to provide a 7-d grazing period and a 21-d rest period) grazing treatments were assigned to six, 3.0-ha fescue-bluegrass pastures in a randomized complete block design with three replications. Each pasture had six tester animals, and stocking rates were varied using put-and-take animals. Pastures were grazed from 16 April to 8 July 2013 (Year 1) and 20 May to 12 Aug (Year 2) and cattle were blocked by body weight for allotment to pastures. Pasture carrying capacities were greater (P = 0.07) for rotational compared to continuous pastures across both years. Calves on rotationally grazed pastures had greater average daily gain (P = 0.03) and gain per acre (P = 0.05) than those on the continuous treatment across both years. Canopies of continuously grazed pastures contained less (P = 0.01) tall fescue than those in rotationally grazed pastures. Herbage in pre-grazed paddocks had less NDF and ADF than post-grazed paddocks and continuously grazed pastures in 2013 (P < 0.10), but did not differ in 2014 (P > 0.10). In vitro digestible dry matter was greater (P = 0.07) in pre-graze rotational pastures in 2013 compared with continuous and post-graze rotational, and IVDDM did not differ (P < 0.01) between pre-graze rotational and continuous in 2014, but was greater than post-graze rotational. Crude protein was lower (P = 0.06) in both years in post-graze rotational pasture than in continuous or pre-graze rotational pasture, which did not differ. In 2013, there was no difference (P = 0.60) in root WSC among treatments; however, in 2014, WSC levels were greater (P = 0.01) in rotationally grazed pastures compared with continuously grazed pastures. This grazing experiment indicated that rotational grazing of Chaparral treated fescue-bluegrass mixtures can improve both animal performance and the sustainability of pasture productivity.
500

Endocrine studies in stroke patients

Olsson, Tommy January 1989 (has links)
There are a number of links between the endocrine system and the nervous system. In this study, the impact of ischemic stroke on the endocrine system was investigated. Elderly volunteers were studied because data regarding the influence of advanced age on endocrine parameters were lacking. Only small differences in pituitary-thyroid and pituitary-adrenal hormone axes were found between two groups of elderly patients, 60 and 80 years of age. The 80-year-old age group had a lower thyrotropin response to thyrotropin releasing hormone (TRH) and a decline in dopamine excretion. Patients with acute ischemic stroke showed a pronounced hypercortisolism studied by the dexamethasone test and urine free cortisol measurements. In multiple regression analyses, postdexamethasone cortisol levels were positively correlated to proximity of the lesion to the frontal pole of the brain and disorientation. Urine cortisol levels were predicted by limb paresis, disorientation and body temperature. High cortisol excretion was associated with a worse functional outcome. Norepinephrine excretion was correlated to urine cortisol levels and to motor impairment. Patients with acute stroke had elevated free thyroxin indices. A paradoxical growth hormone response to TRH was found in the majority of stroke patients. In a multiple regression model disorientation was negatively correlated to thyrotropin response after TRH and positively correlated to prolactin response. Growth hormone response to TRH was associated with extensive paresis. In a cohort study diabetic and non-diabetic patients were prospectively studied after an initial stroke. Diabetes mellitus adversely influenced survival, the risk for a recurrent stroke and myocardial infarction. / <p>S. 1-66: sammanfattning, s. 69-190: 6 uppsatser</p> / digitalisering@umu

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