Spin injection and spin accumulation in permalloy-copper mesoscopic spin valves

We study the electrical injection and detection of spin currents in a lateral spin valve device, using permalloy (Py) as ferromagnetic injecting and detecting electrodes and copper (Cu) as non-magnetic metal. Our multi-terminal geometry allows us to experimentally distinguish different magneto resistance signals, being 1) the spin valve effect, 2) the anomalous magneto resistance (AMR) effect and 3) Hall effects. We find that the AMR contribution of the Py contacts can be much bigger than the amplitude of the spin valve effect, making it impossible to observe the spin valve effect in a 'conventional' measurement geometry. However, these 'contact' magneto resistance signals can be used to monitor the magnetization reversal process, making it possible to determine the magnetic switching fields of the Py contacts of the spin valve device. In a 'non local' spin valve measurement we are able to completely isolate the spin valve signal and observe clear spin accumulation signals at T=4.2 K as well as at room temperature. We obtain spin diffusion lengths in copper of 1 micrometer and 350 nm at T=4.2 K and room temperature respectively.Comment: 8 pages (incl. figures), 7 figures, RevTex, conferenc

Modality-specific Affective Responses and their Implications for Affective BCI

Reliable applications of multimodal affective brain-computer interfaces (aBCI) require a detailed understanding of the processes involved in emotions. To explore the modality-specific nature of affective responses, we studied neurophysiological responses of 24 subjects during visual, auditory, and audiovisual affect stimulation and obtained their subjective ratings. Coherent with literature, we found modality-specific responses in the EEG: parietal alpha power decreases during visual stimulation and increases during auditory stimulation, whereas more anterior alpha power decreases during auditory stimulation and increases during visual stimulation. We discuss the implications of these results for multimodal aBCI

Highly efficient room temperature spin injection in a metal-insulator-semiconductor light emitting diode

We demonstrate highly efficient spin injection at low and room temperature in an AlGaAs/GaAs semiconductor heterostructure from a CoFe/AlOx tunnel spin injector. We use a double-step oxide deposition for the fabrication of a pinhole-free AlOx tunnel barrier. The measurements of the circular polarization of the electroluminescence in the Oblique Hanle Effect geometry reveal injected spin polarizations of at least 24% at 80K and 12% at room temperature

Determinants of caregiving experiences and mental health of partners of cancer patients

BACKGROUND. Research regarding informal caregiving showed considerable individual variation in responses to cancer caregiving. The current longitudinal study examined determinants of caregiver outcomes in terms of caregiver experiences at 3 months and caregiver's mental health at 6 months after hospital discharge. It included both negative and positive dimensions of caregiving outcomes.METHODS. One hundred forty-eight patients with newly diagnosed colorectal carcinoma and their partners were included. Caregiver experiences were assessed by the Caregiver Reaction Assessment Scale, which contains four negative subscales (disrupted schedule, financial problems, lack of family support, and loss of physical strength) and one positive subscale (self-esteem). The mental health of the caregiver was assessed in terms of depression and quality of life. Possible determinants of the caregiver's experiences and mental health were categorized according to characteristics of the caregiver, the patient, and the care situation. Caregiving experiences were studied as a fourth additional category of possible determinants of the caregiver's mental health.RESULTS. Each domain of the caregiving experience was explained by different factors, with total explained variances ranging between 11-46%. Negative caregiver experiences were associated with a low income, living with only the patient, a distressed relationship, a high level of patient dependency, and a high involvement in caregiving tasks. Caregivers with a low level of education and caregivers of patients with a stoma were able to derive more self-esteem from caregiving. Although caregiving may lead to depression, especially in those experiencing loss of physical strength, caregivers may sustain their quality of life by deriving self-esteem from caregiving.CONCLUSIONS. It is important that professionals involved in the ongoing care of cancer patients and their families be aware of the increasing demands made on caregivers and the specific problems and uplifts they perceive in caregiving. Professional caregivers are urged to involve informal caregivers with care explicitly and continuously. However, specific attention to those caregivers who live only with the patient, those with a low income, those with a distressed relationship, and those with a high level of patient dependency and care involvement is warranted. Cancer 1999;86:577-88. (C) 1999 American Cancer Society.</p

Brain computer interfaces as intelligent sensors for enhancing human-computer interaction

BCIs are traditionally conceived as a way to control apparatus, an interface that allows you to act on" external devices as a form of input control. We propose an alternative use of BCIs, that of monitoring users as an additional intelligent sensor to enrich traditional means of interaction. This vision is what we consider to be a grand challenge in the field of multimodal interaction. In this article, this challenge is introduced, related to existing work, and illustrated using some best practices and the contributions it has received