A study of the slow reaction in Al-5 wt.% Ag alloy by resistivity measurements

The slow reaction in an Al-5 wt.% Ag alloy has been investigated by resistivity measurements. The "slope change" method gave an activation energy of 1.25 eV for silver diffusion during the slow reaction. The existence of an excess concentration of vacancies in equilibrium with the dislocation loops seems to be responsible for the slow reaction. The presence of silver inhibits the nucleation of dislocation loops by holding up the quenched-in vacancies in solution. There is no indication of the presence of a third stage in the low-temperature ageing process of this alloy.

Monetary Policy Implementation in the Interbank Market

The liquidity crisis that swept through the financial markets in 2007 triggered multi-billion losses and forced buyouts of some large banks. The resulting credit crunch is sometimes compared to the great recession in the early twentieth century. But the crisis also serves as a reminder of the significance of the interbank market and of proper central bank policy in this market. This thesis deals with implementation of monetary policy in the interbank market and examines how central bank tools affect commercial banks' decisions. I answer the following questions: • What is the relationship between the policy setup and interbank interest rate volatility? (averaging reserve requirement reduces the volatility) • What can explain a weak relationship between market liquidity and the interest rate? (high reserve requirement buffer) • What determines banks' decisions on when to satisfy the reserve requirement? (market frictions) • How did the liquidity crisis that began in 2007 affect interbank market behaviour? (resulted in higher credit risk and trading frictions as well as expected liquidity shortage)

Use of metastable equilibria for determination of Gibbs energy of solids

Attempts are made to measure activities of both components of a binary alloy (A�B) at 650 K using a solid-state galvanic cell incorporating a new composite solid electrolyte. Since the ionic conductivity of the composite solid electrolyte is three orders of magnitude higher than that of pure CaF2, the cell can be operated at lower temperatures. The alloy phase is equilibrated in separate experiments with flourides of each component and fluorine potential is measured. The mixture of the alloy (A�B) and the fluoride of the more reactive component (BF2) is stable, while (A�B) + AF2 mixture is metastable, Factors governing the possible use of metastable equilibria have been elucidated in this study. In the Co�Ni system, where the difference in Gibbs energies of formation of the fluorides is 21.4 kJ/mol, emf of the cell with metastable phases at the electrode is constant for periods ranging from 90 to 160 ks depending on alloy composition. Subsequently, the emf decreases because of the onset of the displacement reaction. In the Ni�Mn system, measurement of the activity of Ni using metastable equilibria is not fully successful at 650 K because of the large driving force for the displacement reaction (208.8 kJ/mol). Critical factors in the application of metastable equilibria are the driving force for displacement reaction and diffusion coefficients in both the alloy and fluoride solid solution.

Neural network based approach to standard cell placement

We propose a novel algorithm for placement of standard cells in VLSI circuits based on an analogy of this problem with neural networks. By employing some of the organising principles of these nets, we have attempted to improve the behaviour of the bipartitioning method as proposed by Kernighan and Lin. Our algorithm yields better quality placements compared with the above method, and also makes the final placement independent of the initial partition.

Eri maitohappobakteerien ja niiden annostustason vaikutus säilörehun käymislaatuun ja aerobiseen stabiilisuuteen

Tämän maisterin tutkielman tarkoituksena oli testata eri maitohappobakteerien ja niiden annostustason vaikutusta säilörehun käymislaatuun ja aerobiseen stabiilisuuteen. Biologisilla säilöntäaineilla eli ympeillä säilöttyjen rehujen laatua verrattiin kontrolleina toimiviin painorehuun ja muurahaishapolla tehtyyn rehuun. Koerehut tehtiin Helsingin yliopiston Maataloustieteiden laitoksella 7.6.2010. Timotei (Phleum pratense) - nurminata (Festuca pratensis) kasvusto korjattiin tähkimisen alkuvaiheessa D-arvon ollessa 711 g/kg ka. Nurmikasvuston kuiva-ainepitoisuus oli 170 g/kg heti niiton jälkeen määritettäessä ja neljän tunnin esikuivauksen jälkeen 208 g/kg. Rehuraaka-aine jaettiin kuuteen erään, joihin lisättiin säilöntäaine. Säilöntäainekäsittelyt olivat: 1) ei säilöntäainetta (painorehu), 2) muurahaishappo (100 %:na 4 l/t), 3) Lactobacillus plantarum ja Pediococcus acidilactici 1x10? pmy/g sekä pektinaasi-, ksylanaasi- ja sellulaasientsyymi, 4) L. plantarum 1x10? pmy/g, 5) L. plantarum 1x10? pmy/g ja 6) L. plantarum ja L. buchneri 2x10? pmy/g. Rehut säilöttiin laboratoriosiiloissa kolmena rinnakkaisena. Laboratoriosiilojen lisäksi rehua säilöttiin jokaisesta säilöntäainekäsittelystä kuuteen rinnakkaiseen minisiiloon säilönnän alkuajan fermentaation ja rehujen pH:n muutoksen seuraamiseksi. Minisiiloista seurattiin kaasuntuotantoa 21 päivän ajan. Raaka-aineen koostumus ja rehujen säilönnällinen laatu sekä aerobinen stabiilisuus määritettiin. Säilörehujen kuiva-ainepitoisuus oli suhteellisen pieni (n. 210 g/kg), jotta voitiin testata biologisten säilöntäaineiden tehoa märässä rehussa. Kosteassa rehussa biologisten säilöntäaineiden toiminnan onnistuminen on haastavaa. Koska raaka-aineen sokeripitoisuus oli kuitenkin erittäin suuri (196 g/kg ka), onnistui ymppirehujen säilöntä hyvin. Kaikkien koerehujen pH oli alle 4:n. Painorehu ei täyttänyt hyvän rehun kriteerejä ammoniumtypen osalta. Muurahaishapporehu oli laadultaan tyydyttävää etikkahapon pitoisuuden osalta. Rehussa tapahtui epätyypillistä etanolikäymistä hiivojen toimesta, jonka johdosta rehussa muodostui suuri määrä kaasua säilönnän aikana. Muurahaishapporehu ei kuitenkaan lämmennyt aerobisen stabiilisuuden mittauksen aikana, johtuen todennäköisesti suuresta etikkahapon määrästä ja toisaalta pienestä sokerin määrästä. Maitohappobakteerisäilöntäaineilla saatiin käymislaadultaan parempaa säilörehua verrattuna painorehuun, lukuun ottamatta maitohappobakteeri-entsyymirehua. Entsyymilisäyksestä ei todennäköisesti ollut hyötyä rehun säilöntälaadun kannalta. Raaka-aineen suuren sokeripitoisuuden johdosta säilörehussa oli koko säilönnän ajan tarpeeksi sokeria maitohappobakteerien käytettäväksi ja sokeri toimi siten substraattina haitallisille mikrobeille tuottaen suuren etikkahappopitoisuuden. Maitohappobakteeri-entsyymiseoksella tehty rehu oli etikkahappopitoisuuden perusteella heikkolaatuista. Lactobacillus plantarumin molemmilla annostustasoilla (1x10? ja 1x10? pmy/g rehua) saatiin laadultaan hyvää rehua. Suuri sokeripitoisuus molemmissa rehuissa johtui todennäköisesti raaka-aineen tavallista suuremmasta sokerin määrästä. Molempien rehujen maitohappo-etikkahappo-suhde oli melko korkea, viitaten homofermentatiiviseen maitohappokäymiseen. Lactobacillus buchneri –lisäyksellä rehu oli säilönnälliseltä laadultaan hyvää. Heterofermentatiivisen ympin lisäys nosti tyypillisesti rehun pH:ta sekä pienensi maitohappoetikkahappo-suhdelukua verrattuna homofermentatiiviseen ymppiin. L. buchneri –lisäys paransi hieman säilörehun aerobista stabiilisuutta verrattuna homofermentatiivisella maitohappobakteerilla säilöttyyn rehuun, mutta tulos ei ollut tilastollisesti merkitsevä.

Genetic polymorphisms and laboratory variables as predictors of blood pressure response to antihypertensive drugs

Hypertension is one of the major risk factors for cardiovascular morbidity. The advantages of antihypertensive therapy have been clearly demonstrated, but only about 30% of hypertensive patients have their blood pressure (BP) controlled by such treatment. One of the reasons for this poor BP control may lie in the difficulty in predicting BP response to antihypertensive treatment. The average BP reduction achieved is similar for each drug in the main classes of antihypertensive agents, but there is a marked individual variation in BP responses to any given drug. The purpose of the present study was to examine BP response to four different antihypertensive monotherapies with regard to demographic characteristics, laboratory test results and common genetic polymorphisms. The subjects of the present study are participants in the pharmacogenetic GENRES Study. A total of 208 subjects completed the whole study protocol including four drug treatment periods of four weeks, separated by four-week placebo periods. The study drugs were amlodipine, bisoprolol, hydrochlorothiazide and losartan. Both office (OBP) and 24-hour ambulatory blood pressure (ABP) measurements were carried out. BP response to study drugs were related to basic clinical characteristics, pretreatment laboratory test results and common polymorphisms in genes coding for components of the renin-angiotensin system, alpha-adducin (ADD1), beta1-adrenergic receptor (ADRB1) and beta2-adrenergic receptor (ADRB2). Age was positively correlated with BP responses to amlodipine and with OBP and systolic ABP responses to hydrochlorothiazide, while body mass index was negatively correlated with ABP responses to amlodipine. Of the laboratory test results, plasma renin activity (PRA) correlated positively with BP responses to losartan, with ABP responses to bisoprolol, and negatively with ABP responses to hydrochlorothiazide. Uniquely to this study, it was found that serum total calcium level was negatively correlated with BP responses to amlodipine, whilst serum total cholesterol level was negatively correlated with ABP responses to amlodipine. There were no significant associations of angiotensin II type I receptor 1166A/C, angiotensin converting enzyme I/D, angiotensinogen Met235Thr, ADD1 Gly460Trp, ADRB1 Ser49Gly and Gly389Arg and ADRB2 Arg16Gly and Gln27Glu polymorphisms with BP responses to the study drugs. In conclusion, this study confirmed the relationship between pretreatment PRA levels and response to three classes of antihypertensive drugs. This study is the first to note a significant inverse relation between serum calcium level and responsiveness to a calcium channel blocker. However, this study could not replicate the observations that common polymorphisms in angiotensin II type I receptor, angiotensin converting enzyme, angiotensinogen, ADD1, ADRB1, or ADRB2 genes can predict BP response to antihypertensive drugs.

Blade manipulators in turbulent channel flow

We report here the results of a series of careful experiments in turbulent channel flow, using various configurations of blade manipulators suggested as optimal in earlier boundary layer studies. The mass flow in the channel could be held constant to better than 0.1%, and the uncertainties in pressure loss measurements were less than 0.1 mm of water; it was therefore possible to make accurate estimates of the global effects of blade manipulation of a kind that are difficult in boundary layer flows. The flow was fully developed at the station where the blades were mounted, and always relaxed to the same state sufficiently far downstream. It is found that, for a given mass flow, the pressure drop to any station downstream is always higher in the manipulated than in the unmanipulated flow, demonstrating that none of the blade manipulators tried reduces net duct losses. However the net increase in duct losses is less than the drag of the blade even in laminar flow, showing that there is a net reduction in the total skin friction drag experienced by the duct, but this relief is only about 20% of the manipulator drag at most.

Impaired conflict monitoring in Parkinson's disease patients during an oculomotor redirect task

Fallibility is inherent in human cognition and so a system that will monitor performance is indispensable. While behavioral evidence for such a system derives from the finding that subjects slow down after trials that are likely to produce errors, the neural and behavioral characterization that enables such control is incomplete. Here, we report a specific role for dopamine/basal ganglia in response conflict by accessing deficits in performance monitoring in patients with Parkinson's disease. To characterize such a deficit, we used a modification of the oculomotor countermanding task to show that slowing down of responses that generate robust response conflict, and not post-error per se, is deficient in Parkinson's disease patients. Poor performance adjustment could be either due to impaired ability to slow RT subsequent to conflicts or due to impaired response conflict recognition. If the latter hypothesis was true, then PD subjects should show evidence of impaired error detection/correction, which was found to be the case. These results make a strong case for impaired performance monitoring in Parkinson's patients.

Structure and superconducting properties of a new family of thallium cuprates, TlSr3−xLnxCu2O7

Cuprates of the formula TlSr3−xLnxCu2O7 (Ln=Pr, NdorY) derived from the hypothetical TlSr3Cu2O7 show superconductivity with Tcs up to 95 K when 0.5less, approximatex≤0.75, the x=1.0 compositions being insulators. Rietveld analysis of X-ray diffraction profiles has been carried out for two superconducting members of this family. The unit cell a-parameter, and hence the in-plane Cu-O distance, increases with increase in x. The Tc value decreases with increase in x or the in-plane Cu-O distance in all the series of cuprates. Superconductivity in the Tl1−yPbySr3−xNdxCu2O7 systems is found with the highest Tc of 95 K when y=0.2 and x=0.5. The in-plane Cu-O distances in all the cuprates studied fall in the range found in the Sr-class of cuprate superconductors.

A quasi-steady performance prediction model for dynamic characteristics of a volute pump

A performance prediction model generally applicable for volute-type centrifugal pumps has been extended to predict the dynamic characteristics of a pump during its normal starting and stopping periods. Experiments have been conducted on a volute pump with different valve openings to study the dynamic behaviour of the pump during normal start-up and stopping, when a small length of discharge pipeline is connected to the discharge flange of the pump. Such experiments have also been conducted when the test pump was part of a hydraulic system, an experimental rig, where it is pumping against three similar pumps, known as supply pumps, connected in series, with the supply pumps kept idle or running. Instantaneous rotational speed, flowrate, and delivery and suction pressures of the pump were recorded and it was observed in all the tested cases that the change of pump behaviour during the transient period was quasi-steady, which validates the quasi-steady approach presented in this paper. The nature of variation of parameters during the transients has been discussed. The model-predicted dynamic head-capacity curves agree well with the experimental data for almost all the tested cases.

Modification of photochemical reactivity on formation of inclusion complexes: photorearrangement of benzyl phenyl ethers and methyl phenoxyacetates

The photorearrangement of benzyl phenyl ethers and methyl phenoxyacetates was investigated in methanol and in complexes with cyclodextrin in both the solid state and aqueous solutions. Irradiation in cyclodextrin media leads to a large change in product distribution with a very significant ortho selectivity different from that found in methanol where the reaction is non-selective. For meta-substituted ethers and phenoxyacetates, an impressive regioselectivity between the two ortho-rearranged isomers is observed and this is significantly enhanced by increasing the substituent chain length which acts as a spacer to induce a tight fit between the host and the guest. The observed results are rationalized on the basis of specific orientations of the unsubstituted and meta-substituted ethers and phenoxyacetates in the cyclodextrin cavity.

Unsteady compressible flow due to relative rotation and translation of a viscous fluid on a disk

The modification of the axisymmetric viscous flow due to relative rotation of the disk or fluid by a translation of the boundary is studied. The fluid is taken to be compressible, and the relative rotation and translation velocity of the disk or fluid are time-dependent. The nonlinear partial differential equations governing the motion are solved numerically using an implicit finite difference scheme and Newton's linearisation technique. Numerical solutions are obtained at various non-dimensional times and disk temperatures. The non-symmetric part of the flow (secondary flow) describing the translation effect generates a velocity field at each plane parallel to the disk. The cartesian components of velocity due to secondary flow exhibit oscillations when the motion is due to rotation of the fluid on a translating disk. Increase in translation velocity produces an increment in the radial skin friction but reduces the tangential skin friction.