Wet oxidation of GeSi at (700)C

About 500-nm-thick films of Ge0.36Si0.64 and Ge0.28Si0.72 grown epitaxially on (100)Si have been oxidized at 700-degrees-C in wet ambient. A uniform GexSi1-xO2 oxide layer forms with a smooth interface between it and the unoxidized GexSi1-x layer below. The composition and structure of that layer remains unchanged as monitored by backscattering spectrometry or cross-sectional transmission electronic microscopy. The oxide of both samples grows as square root of oxidation duration. The parabolic rate constant increases with the Ge content and is larger than that for wet oxidation of pure Si at the same temperature. The absence of a regime of linear growth at this relatively low temperature indicates a much enhanced linear rate constant

Elastic precession of electronic spin states in interacting integer quantum Hall edge channels

We consider the effect of Coulomb interactions in the propagation of electrons, prepared in arbitrary spin states, on chiral edge channels in the integer quantum Hall regime. Electrons are injected and detected at the same energy at different locations of the Hall bar, which is modeled as a chiral Tomonaga-Luttinger liquid. The current is computed perturbatively in the tunneling amplitudes, within a non-crossing approximation using exact solutions of the interacting Green's functions. In the case of different channel velocities, the spin precession effect is evaluated, and the role of interaction parameters and wavevectors is discussed.Comment: 5 pages, 3 figure

Portraits of care: medical research through portraiture

The Portraits of Care study used portraiture to investigate ideas about care and care giving at the intersection of art and medicine. The study employed mixed methods involving both qualitative and quantitative research techniques. All aspects of the study were approved by the Institutional Review Board. The study included 26 patient and 20 caregiver subjects. Patient subjects were drawn from across the lifespan and included healthy and ill patients. Caregiver subjects included professional and familial caregivers. All subjects gave their informed consent for the study and the subsequent exhibition of artwork. The artist drew or painted 100 portraits during the 2-year study. A multi-disciplinary analysis team carried out the initial analysis of portraits and subject data. Findings from their qualitative analysis were used to develop a quantitative survey and qualitative journal tool that the public used to give feedback at the subsequent exhibition. Exhibition data confirmed the initial findings. Study results showed the introspection of subjects that revealed their sense of identity and psychological status. Patients appear as ‘whole people’, not fragmented by diagnosis. Caregivers\u27 portraits reveal their commitment to care. There is also a sense of mutuality and fluidity in the background stories of subjects. Many patient subjects have been caregivers and, at times, caregivers are also patients. Public data emphasised the identity transformation of subjects, the centrality of the idea of mortality, the presence of hope despite adversity, and the importance of empathy and compassion in care

Transient effects in the backscattered current of a Luttinger liquid

We study the backscattered current in a Luttinger liquid in the presence of a point like weak impurity switched on at finite time, taking into account finite-temperature effects. We show how the well-known results for a static impurity are distorted. We derive a dimensionless parameter $\tau_{R}$ as function of the electron-electron interaction and the temperature, such that for $\tau_{R} 1$) the switching process is relevant (irrelevant). Our results suggest the possibility of determining the value of the Luttinger parameter $K$ through time measurements in transport experiments at fixed voltage.Comment: 8 pages, 3 figures. To appear in Physical Review

Effects of hypophyseal or thymic allograft on thymus development in partially decerebrated chicken embryos: expression of PCNA and CD3 markers

Changes in chicken embryo thymus after partial decerebration (including the hypophysis) and after hypophyseal or thymic allograft were investigated. Chicken embryos were partially decerebrated at 36–40 h of incubation and on day 12 received a hypophysis or a thymus allograft from 18-day-old donor embryos. The thymuses of normal, sham-operated and partially decerebrate embryos were collected on day 12 and 18. The thymuses of the grafted embryos were collected on day 18. The samples were examined with histological method and tested for the anti-PCNA and anti-CD3 immune-reactions. After partial decerebration, the thymic cortical and medullary compartments diminished markedly in size. Anti-PCNA and anti-CD3 revealed a reduced immunereaction, verified also by statistical analysis. In hypophyseal or grafted embryos, the thymic morphological compartments improved, the anti-PCNA and anti-CD3 immune-reactions recovered much better after the thymic graft, probably due to the thymic growth factors and also by an emigration of thymocytes from the same grafted thymus

Exposing the human nude phenotype [4]

Peer reviewedSubmitted Versio

Portrait of a process: arts-based research in a head and neck cancer clinic

The role of art in medicine is complex, varied and uncertain. To examine one aspect of the relationship between art and medicine, investigators analysed the interactions between a professional artist and five adult patients with head and neck cancer as they cocreated portraits in a clinical setting. The artist and four members of an interdisciplinary team analysed the portraits as well as journal entries, transcripts of portrait sessions and semistructured interviews. Over the course of 5 months, 24 artworks evolved from sittings that allowed both the patients and the artist to collaborate around stories of illness, suffering and recovery. Using narrative inquiry and qualitative arts-based research techniques five emergent themes were identified: embracing uncertainties; developing trusting relationships; engaging in reflective practices; creating shared stories; and empowerment. Similar themes are found in successful physician–patient relationships. This paper will discuss these findings and potential implications for healthcare and medical education

Experimental Rugged Fitness Landscape in Protein Sequence Space

The fitness landscape in sequence space determines the process of biomolecular evolution. To plot the fitness landscape of protein function, we carried out in vitro molecular evolution beginning with a defective fd phage carrying a random polypeptide of 139 amino acids in place of the g3p minor coat protein D2 domain, which is essential for phage infection. After 20 cycles of random substitution at sites 12–130 of the initial random polypeptide and selection for infectivity, the selected phage showed a 1.7×10(4)-fold increase in infectivity, defined as the number of infected cells per ml of phage suspension. Fitness was defined as the logarithm of infectivity, and we analyzed (1) the dependence of stationary fitness on library size, which increased gradually, and (2) the time course of changes in fitness in transitional phases, based on an original theory regarding the evolutionary dynamics in Kauffman's n-k fitness landscape model. In the landscape model, single mutations at single sites among n sites affect the contribution of k other sites to fitness. Based on the results of these analyses, k was estimated to be 18–24. According to the estimated parameters, the landscape was plotted as a smooth surface up to a relative fitness of 0.4 of the global peak, whereas the landscape had a highly rugged surface with many local peaks above this relative fitness value. Based on the landscapes of these two different surfaces, it appears possible for adaptive walks with only random substitutions to climb with relative ease up to the middle region of the fitness landscape from any primordial or random sequence, whereas an enormous range of sequence diversity is required to climb further up the rugged surface above the middle region