Pairing, Ferromagnetism, and Condensation of a normal spin-1 Bose gas

We theoretically study the stability of a normal, spin disordered, homogenous spin-1 Bose gas against ferromagnetism, pairing, and condensation through a Random Phase Approximation which includes exchange (RPA-X). Repulsive spin-independent interactions stabilize the normal state against both ferromagnetism and pairing, and for typical interaction strengths leads to a direct transition from an unordered normal state to a fully ordered single particle condensate. Atoms with much larger spin-dependent interaction may experience a transition to a ferromagnetic normal state or a paired superfluid, but, within the RPA-X, there is no instability towards a normal state with spontaneous nematic order. We analyze the role of the quadratic Zeeman effect and finite system size.Comment: 4 pages, 3 figures, 1 table. Supplementary materials attache

Who Cares? The Role Of Job Involvement In Psychological Contract Violation

This study examined survey data from full-time employees employed in a variety of occupations. We empirically examined how psychological involvement with one’s job affects reactions to psychological contract violation. Data for control variables (i.e., age, gender, organizational tenure), the independent variable (i.e., psychological contract violation), and the moderator (i.e., job involvement) were taken at Time 1; and dependent variables (i.e., depressed mood at work, turnover intention) were taken at Time 2. Results illustrated that job involvement was an important construct in understanding individuals’ negative reactions to psychological contract violations. Implications and limitations are discussed, and suggestions for future research are offered

Who Cares? The Role Of Job Involvement In Psychological Contract Violation

This study examined survey data from full-time employees employed in a variety of occupations. We empirically examined how psychological involvement with one’s job affects reactions to psychological contract violation. Data for control variables (i.e., age, gender, organizational tenure), the independent variable (i.e., psychological contract violation), and the moderator (i.e., job involvement) were taken at Time 1; and dependent variables (i.e., depressed mood at work, turnover intention) were taken at Time 2. Results illustrated that job involvement was an important construct in understanding individuals’ negative reactions to psychological contract violations. Implications and limitations are discussed, and suggestions for future research are offered

Validity of the scattering length approximation in strongly interacting Fermi systems

We investigate the energy spectrum of systems of two, three and four spin-1/2 fermions with short range attractive interactions both exactly, and within the scattering length approximation. The formation of molecular bound states and the ferromagnetic transition of the excited scattering state are examined systematically as a function of the 2-body scattering length. Identification of the upper branch (scattering states) is discussed and a general approach valid for systems with many particles is given. We show that an adiabatic ferromagnetic transition occurs, but at a critical transition point kF a much higher than predicted from previous calculations, almost all of which use the scattering length approximation. In the 4-particle system the discrepancy is a factor of 2. The exact critical interaction strength calculated in the 4-particle system is consistent with that reported by experiment. To make comparisons with the adiabatic transition, we study the quench dynamics of the pairing instability using the eigenstate wavefunctions.Comment: 7 pages, 7 figure

Magnetism of 3d transition metal atoms on W(001): submonolayer films

We have investigated random submonolayer films of 3d transition metals on W(001). The tight-binding linear muffin-tin orbital method combined with the coherent potential approximation was employed to calculate the electronic structure of the films. We have estimated local magnetic moments and the stability of different magnetic structures, namely the ferromagnetic order, the disordered local moments and the non-magnetic state, by comparing the total energies of the corresponding systems. It has been found that the magnetic moments of V and Cr decrease and eventually disappear with decreasing coverage. On the other hand, Fe retains approximately the same magnetic moment throughout the whole concentration range from a single impurity to the monolayer coverage. Mn is an intermediate case between Cr and Fe since it is non-magnetic at very low coverages and ferromagnetic otherwise.Comment: 5 pages, 3 figures in 6 files; presented at ICN&T 2006, Basel, Switzerlan

Spin Josephson effect in ferromagnet/ferromagnet tunnel junctions

We consider the tunnel spin current between two ferromagnetic metals from a perspective similar to the one used in superconductor/superconductor tunnel junctions. We use fundamental arguments to derive a Josephson-like spin tunnel current $I_J^{\rm spin}\propto\sin(\theta_1-\theta_2)$. Here the phases are associated with the planar contribution to the magnetization, $\sim e^{i\theta}$. The crucial step in our analysis is the fact that the $z$-component of the spin is canonically conjugate to the phase of the planar contribution: $[\theta,S^z]=i$. This is analogous to the commutation relation $[\phi,N]=i$ in superconductors, where $\phi$ is the phase associated to the superconducting order parameter and $N$ is the Cooper pair number operator. We briefly discuss the experimental consequences of our theoretical analysis.Comment: LaTex, seven pages, no figures; version to appear in Europhys. Lett.; in order to make room for a more extended microscopic analysis, the phenomenological discussion contained in v2 was remove

Effect of Reducing Atmosphere on the Magnetism of Zn1-xCoxO Nanoparticles

We report the crystal structure and magnetic properties of Zn1-xCoxO nanoparticles synthesized by heating metal acetates in organic solvent. The nanoparticles were crystallized in wurtzite ZnO structure after annealing in air and in a forming gas (Ar95%+H5%). The X-ray diffraction and X-ray photoemission spectroscopy (XPS) data for different Co content show clear evidence for the Co+2 ions in tetrahedral symmetry, indicating the substitution of Co+2 in ZnO lattice. However samples with x=0.08 and higher cobalt content also indicate the presence of Co metal clusters. Only those samples annealed in the reducing atmosphere of the forming gas, and that showed the presence of oxygen vacancies, exhibited ferromagnetism at room temperature. The air annealed samples remained non-magnetic down to 77K. The essential ingredient in achieving room temperature ferromagnetism in these Zn1-xCoxO nanoparticles was found to be the presence of additional carriers generated by the presence of the oxygen vacancies.Comment: 11 pages, 6 figures, submitted to Nanotechnology IO

Implications of subcutaneous or intravenous delivery of trastuzumab: further insight from patient interviews in the PrefHer study

BACKGROUND: The 2 Cohort randomised PrefHer trial examined the preferences of HER2+ve primary breast cancer patients for intravenous (IV) or subcutaneous (SC) delivery of trastuzumab via a Single Injectable Device (SID) or hand-held syringe (HHS). The novel approach and design of the study permitted an in-depth exploration of patients' experiences, the impact that different modes of delivery had on patients' well-being and implications for future management. METHODS: The preferences, experiences and general comments of patients in the PrefHer study were collected via specific semi-structured interview schedules. Exploratory analyses of data were conducted using standard methodology. The final question invited patients to make further comments, which were divided into 9 thematic categories - future delivery, compliments, time/convenience, practical considerations, pain/discomfort, study design, side-effects, psychological impact, and perceived efficacy. RESULTS: 267/467 (57%) patients made 396 additional comments, 7 were neutral, 305 positive and 86 negative. The three top categories generating the largest number of comments were compliments and gratitude about staff and being part of PrefHer (75/396; 19%), the potential future delivery of SC trastuzumab (73/396; 18%), and practical considerations about SC administration (60/396; 15%). CONCLUSIONS: Eliciting patient preferences about routes of administration of drugs via comprehensive interviews within a randomised cross-over trial yielded rich and important information. The few negative comments made demonstrated a need for proper staff training in SC administration Patients were grateful to have been part of the trial, and would have liked to continue with SC delivery. The possibility of home administration in the future also seemed acceptable. EUDRACT NUMBER: 2010-024099-25