Master of Science

thesisThe Residency Review Committee (RRC) requires that general surgery residents document their Surgical Intensive Care Unit (SICU) experiences. To satisfy these requirements we created a web based intranet log to make it easier for residents to track their patients and determine when these requirements were complete. A premium was put on usability to promote acceptance by surgical residents. A prototype web site was designed with input from an attending general surgeon. Three general surgery residents were selected to participate in the iterative design phase. They went through three iterations using a "think-aloud" method while performing tasks on the prototype web site. Each iteration led to improvements to the web site. In a comparison test, a group of seven medical students performed 14 typical web site tasks using both the prototype and the final versions. They were asked to complete a Questionnaire for User Interaction Satisfaction (QUIS) for each version. The time for completion of these tasks was also recorded. The user interaction satisfaction did not show any improvement (F(1,6)=0.13, p=0.912). Similarly, there was no improvement in times for delete and add tasks ( Delete F(1,5) = 0.949, p=0.375, Add F(1,5)=0.267, p=0.628 ); however, the time to complete edit tasks was faster for the final version of the web site (F (1,5)= 14.3, p=0.013). The primary reason for not detecting other differences between the two web sites is likely that the comparison study did not have sufficient power. This was suggested by the participants whose comments favored the final version over the prototype as well as a trend of consistently higher mean subset scores in the final version. The results indicate that differences may be seen when more complex tasks are completed (editing information) versus the two simpler tasks (adding or deleting a patient record in a web site). Future studies should focus on the impact of navigation strategies on speed and data warehouse approaches to creating the application. This study shows the benefits of using an iterative design approach to create a usable web site and demonstrates the importance of further research in the field of usability

Linear orthogonality preservers of Hilbert bundles

Due to the corresponding fact concerning Hilbert spaces, it is natural to ask if the linearity and the orthogonality structure of a Hilbert $C^*$-module determine its $C^*$-algebra-valued inner product. We verify this in the case when the $C^*$-algebra is commutative (or equivalently, we consider a Hilbert bundle over a locally compact Hausdorff space). More precisely, a $\mathbb{C}$-linear map $\theta$ (not assumed to be bounded) between two Hilbert $C^*$-modules is said to be "orthogonality preserving" if \left =0 whenever \left =0. We prove that if $\theta$ is an orthogonality preserving map from a full Hilbert $C_0(\Omega)$-module $E$ into another Hilbert $C_0(\Omega)$-module $F$ that satisfies a weaker notion of $C_0(\Omega)$-linearity (known as "localness"), then $\theta$ is bounded and there exists $\phi\in C_b(\Omega)_+$ such that \left\ =\ \phi\cdot\left, \quad \forall x,y \in E. On the other hand, if $F$ is a full Hilbert $C^*$-module over another commutative $C^*$-algebra $C_0(\Delta)$, we show that a "bi-orthogonality preserving" bijective map $\theta$ with some "local-type property" will be bounded and satisfy \left\ =\ \phi\cdot\left\circ\sigma, \quad \forall x,y \in E where $\phi\in C_b(\Omega)_+$ and $\sigma: \Delta \rightarrow \Omega$ is a homeomorphism

Linear orthogonality preservers of Hilbert C∗C^*-modules over general C∗C^*-algebras

As a partial generalisation of the Uhlhorn theorem to Hilbert $C^*$-modules, we show in this article that the module structure and the orthogonality structure of a Hilbert $C^*$-module determine its Hilbert $C^*$-module structure. In fact, we have a more general result as follows. Let $A$ be a $C^*$-algebra, $E$ and $F$ be Hilbert $A$-modules, and $I_E$ be the ideal of $A$ generated by $\{\langle x,y\rangle_A: x,y\in E\}$. If $\Phi : E\to F$ is an $A$-module map, not assumed to be bounded but satisfying $$\langle \Phi(x),\Phi(y)\rangle_A\ =\ 0\quad\text{whenever}\quad\langle x,y\rangle_A\ =\ 0,$$ then there exists a unique central positive multiplier $u\in M(I_E)$ such that $$\langle \Phi(x), \Phi(y)\rangle_A\ =\ u \langle x, y\rangle_A\qquad (x,y\in E).$$ As a consequence, $\Phi$ is automatically bounded, the induced map $\Phi_0: E\to \overline{\Phi(E)}$ is adjointable, and $\overline{Eu^{1/2}}$ is isomorphic to $\overline{\Phi(E)}$ as Hilbert $A$-modules. If, in addition, $\Phi$ is bijective, then $E$ is isomorphic to $F$.Comment: 15 page

Zero product preserving linear maps of CCR C∗-algebras with Hausdorff spectrum

AbstractIn this paper, we try to attack a conjecture of Araujo and Jarosz that every bijective linear map θ between C∗-algebras, with both θ and its inverse θ−1 preserving zero products, arises from an algebra isomorphism followed by a central multiplier. We show it is true for CCR C∗-algebras with Hausdorff spectrum, and in general, some special C∗-algebras associated to continuous fields of C∗-algebras

Property (T) for non-unital C*-algebras

Inspired by the recent work of Bekka, we study two reasonable analogues of property (T) for not necessarily unital C*-algebras. The stronger one of the two is called ``property (T)'' and the weaker one is called ``property (T_{e})''. It is shown that all non-unital C*-algebras do not have property (T) (neither do their unitalizations). Moreover, all non-unital $\sigma$-unital C*-algebras do not have property (T_e).Comment: 7 pages; to appear in J. Math. Anal. App

Hemolysis and methemoglobinemia due to hepatitis E virus infection in patient with G6PD deficiency

published_or_final_versionSpringer Open Choice, 21 Feb 201