No description available.

No description available.

Haematocrit in the high normal, as well as the pathological, range may be a risk factor for the development of stroke. As stroke is one of the most important causes of physical handicap attempts to reduce its incidence further are justified. Repeated small volume venesection without volume replacement is a simple method of haematocrit reduction which could be used in a controlled trial if shown to be safe and practicable. Forty three male patients (33 evaluable) with haematocrit above 0.46 without primary proliferative or secondary polycythaemia, were entered into an open study to assess the clinical, haemorheological and haematological sequelae of serial venesection. Haematocrit was reduced from a median of 0.49 to 0.385 which necessitated removal of 2.75 1 of blood (range 1.5 - 4.25 1). This resulted in a marked reduction in blood viscosity which correlated significantly with the change in haematocrit. Although haematocrit has been postulated to affect blood pressure through an effect on blood viscosity and hence peripheral resistance, no clinically significant reduction in blood pressure was observed. Despite producing a slight reactive thrombocytosis, serial venesection was not shown to increase thrombogenic activity. Bleeding time was prolonged significantly and there was a trend for a reduction in platelet adhesion. The reduction in platelet adhesion correlated significantly with the reduction in haematocrit. Maintenance of haematocrit below 0.45 necessitated further venesection on average once every 2 months during follow-up for one year. Two patients with a previous history suffered further strokes which were considered unlikely to be related to venesection. One patient had worsening of angina and 2 patients experienced intermittent palpitations when haematocrit was reduced to 0.40; these events were considered possibly due to an increase in cardiac output as a consequence of lowered haematocrit. Except in patients with cardiac disease, repeated small volume venesection without volume replacement is a safe and practicable method of reducing haematocrit.

No description available.

No description available.

Every second, an enormous volume of data is being gathered from various sources and stored in huge data banks. Most of the time, monitoring a data source requires several parallel measurements, which form a high-dimensional sample vector. Due to the curse of dimensionality, applying machine learning methods, that is, studying and analyzing high-dimensional data, could be difficult. The essential task of dimensionality reduction is to faithfully represent a given set of high-dimensional data samples with a few variables. The goal of this thesis is to develop and propose new techniques for handling high-dimensional data, in order to address contemporary demand in machine learning applications. Most prominent nonlinear dimensionality reduction methods do not explicitly provide a way to handle out-of-samples. The starting point of this thesis is a nonlinear technique, called Embedding by Affine Transformations (EAT), which reduces the dimensionality of out-of-sample data as well. In this method, a convex optimization is solved for estimating a transformation between the high-dimensional input space and the low-dimensional embedding space. To the best of our knowledge, EAT is the only distance-preserving method for nonlinear dimensionality reduction capable of handling out-of-samples. The second method that we propose is TesseraMap. This method is a scalable extension of EAT. Conceptually, TesseraMap partitions the underlying manifold of data into a set of tesserae and then unfolds it by constructing a tessellation in a low-dimensional subspace of the embedding space. Crucially, the desired tessellation is obtained through solving a small semidefinite program; therefore, this method can efficiently handle tens of thousands of data points in a short time. The final outcome of this thesis is a novel method in dimensionality reduction called Isometric Patch Alignment (IPA). Intuitively speaking, IPA first considers a number of overlapping flat patches, which cover the underlying manifold of the high-dimensional input data. Then, IPA rearranges the patches and stitches the neighbors together on their overlapping parts. We prove that stitching two neighboring patches aligns them together; thereby, IPA unfolds the underlying manifold of data. Although this method and TesseraMap have similar approaches, IPA is more scalable; it embeds one million data points in only a few minutes. More importantly, unlike EAT and TesseraMap, which unfold the underlying manifold by stretching it, IPA constructs the unfolded manifold through patch alignment. We show this novel approach is advantageous in many cases. In addition, compared to the other well-known dimensionality reduction methods, IPA has several important characteristics; for example, it is noise tolerant, it handles non-uniform samples, and it can embed non-convex manifolds properly. In addition to these three dimensionality reduction methods, we propose a method for subspace clustering called Low-dimensional Localized Clustering (LDLC). In subspace clustering, data is partitioned into clusters, such that the points of each cluster lie close to a low-dimensional subspace. The unique property of LDLC is that it produces localized clusters on the underlying manifold of data. By conducting several experiments, we show this property is an asset in many machine learning tasks. This method can also be used for local dimensionality reduction. Moreover, LDLC is a suitable tool for forming the tesserae in TesseraMap, and also for creating the patches in IPA.

No description available.

A range of air- and moisture-stable phosphonium salts was prepared. Compounds were isolated in high yield and fully characterized. The properties of these compounds and the nature of their formation were explored. The phosphonium salts react with base to give phosphino-aldehydes which are important building blocks in the synthesis of PNNP ligands. The condensation reaction between phosphino-aldehydes and a diamine usually employed for the preparation of PNNP ligands was not applicable to the phosphino-aldehydes derived from these phosphonium salts as a result of the high reactivity of the nucleophilic phosphorus causing uncontrollable side-reaction. In order to resolve this problem, a template reaction with iron(II) Lewis acid was used to suppress the reactivity of the phosphorus via coordination. The reaction was successful and gave rise to bis-tridentate complexes with PNN ligands ([Fe(Ph2PCH2CH=N---NH2)2][BPh4]2, where N---NH2 depends on diamine used) as the kinetic product and to desired tetradentate complexes with PNNP ligands (trans-[Fe(Ph2PCH2CH=N---N=CHCH2PPh2)(CH3CN)2][BPh4]2, where N---N depends on diamine used) as a thermodynamic product of the reaction. The reaction appeared to be very general; complexes iii with various diamines incorporated in the ligand backbone were prepared in high yield and fully characterized. Mono-carbonylation reaction of the complexes containing tetradentate PNNP ligands resulted in the formation of the precatalysts with a general formula (trans-[Fe(Ph2PCH2CH=N---N=CHCH2PPh2)(CO)(Br)][BPh4]. These precatalysts give active (TOF up to 28000 h-1) and enantioselective (up to 95 % ee) catalytic systems for the ATH of ketones when activated with base in a solution of 2-propanol as the reducing agent. On the basis of a kinetic study and other evidence, we propose a mechanism of activation and operation of the catalytic system involving the precatalyst trans-[Fe(CO)(Br)(Ph2CH2CH=N-((S,S)-C(Ph)H-C(Ph)H)-N=CHCH2PPh2)][BPh4] and acetophenone as a model substrate. We determined that the activation of the precatalyst to the active species involves the stereoselective reduction of one imine group of the ligand, since when the active species are quenched with acid, the complex trans-[Fe(CO)(Cl)(Ph2CH2CH-(H)N-((S,S)-C(Ph)H-C(Ph)H)-N=CHCH2PPh2)][BPh4] containing amine and imine functionalities in the backbone is produced.

A range of air- and moisture-stable phosphonium salts was prepared. Compounds were isolated in high yield and fully characterized. The properties of these compounds and the nature of their formation were explored. The phosphonium salts react with base to give phosphino-aldehydes which are important building blocks in the synthesis of PNNP ligands. The condensation reaction between phosphino-aldehydes and a diamine usually employed for the preparation of PNNP ligands was not applicable to the phosphino-aldehydes derived from these phosphonium salts as a result of the high reactivity of the nucleophilic phosphorus causing uncontrollable side-reaction. In order to resolve this problem, a template reaction with iron(II) Lewis acid was used to suppress the reactivity of the phosphorus via coordination. The reaction was successful and gave rise to bis-tridentate complexes with PNN ligands ([Fe(Ph2PCH2CH=N---NH2)2][BPh4]2, where N---NH2 depends on diamine used) as the kinetic product and to desired tetradentate complexes with PNNP ligands (trans-[Fe(Ph2PCH2CH=N---N=CHCH2PPh2)(CH3CN)2][BPh4]2, where N---N depends on diamine used) as a thermodynamic product of the reaction. The reaction appeared to be very general; complexes iii with various diamines incorporated in the ligand backbone were prepared in high yield and fully characterized. Mono-carbonylation reaction of the complexes containing tetradentate PNNP ligands resulted in the formation of the precatalysts with a general formula (trans-[Fe(Ph2PCH2CH=N---N=CHCH2PPh2)(CO)(Br)][BPh4]. These precatalysts give active (TOF up to 28000 h-1) and enantioselective (up to 95 % ee) catalytic systems for the ATH of ketones when activated with base in a solution of 2-propanol as the reducing agent. On the basis of a kinetic study and other evidence, we propose a mechanism of activation and operation of the catalytic system involving the precatalyst trans-[Fe(CO)(Br)(Ph2CH2CH=N-((S,S)-C(Ph)H-C(Ph)H)-N=CHCH2PPh2)][BPh4] and acetophenone as a model substrate. We determined that the activation of the precatalyst to the active species involves the stereoselective reduction of one imine group of the ligand, since when the active species are quenched with acid, the complex trans-[Fe(CO)(Cl)(Ph2CH2CH-(H)N-((S,S)-C(Ph)H-C(Ph)H)-N=CHCH2PPh2)][BPh4] containing amine and imine functionalities in the backbone is produced.

Typescript. / Thesis (Ph. D.)--University of Hawaii, 1966. / Bibliography: leaves 76-79. / xii, 88 l mounted illus., tables