Dynamics of Spontaneous Magnetization Reversal in Exchange Biased Heterostructures

The dependence of thermally induced spontaneous magnetization reversal on time-dependent cooling protocols was studied. Slower cooling and longer waiting close to the N\`{e}el temperature of the antiferromagnet ($T_N$) enhances the magnetization reversal. Cycling the temperature around $T_N$ leads to a thermal training effect under which the reversal magnitude increases with each cycle. These results suggest that spontaneous magnetization reversal is energetically favored, contrary to our present understanding of positive exchange bias

Dynamic Spin-Polarized Resonant Tunneling in Magnetic Tunnel Junctions

Precisely engineered tunnel junctions exhibit a long sought effect that occurs when the energy of the electron is comparable to the potential energy of the tunneling barrier. The resistance of metal-insulator-metal tunnel junctions oscillates with an applied voltage when electrons that tunnel directly into the barrier's conduction band interfere upon reflection at the classical turning points: the insulator-metal interface, and the dynamic point where the incident electron energy equals the potential barrier inside the insulator. A model of tunneling between free electron bands using the exact solution of the Schroedinger equation for a trapezoidal tunnel barrier qualitatively agrees with experiment.Comment: 4pgs, 3 fig

Speaker-independent emotion recognition exploiting a psychologically-inspired binary cascade classification schema

In this paper, a psychologically-inspired binary cascade classification schema is proposed for speech emotion recognition. Performance is enhanced because commonly confused pairs of emotions are distinguishable from one another. Extracted features are related to statistics of pitch, formants, and energy contours, as well as spectrum, cepstrum, perceptual and temporal features, autocorrelation, MPEG-7 descriptors, Fujisakis model parameters, voice quality, jitter, and shimmer. Selected features are fed as input to K nearest neighborhood classifier and to support vector machines. Two kernels are tested for the latter: Linear and Gaussian radial basis function. The recently proposed speaker-independent experimental protocol is tested on the Berlin emotional speech database for each gender separately. The best emotion recognition accuracy, achieved by support vector machines with linear kernel, equals 87.7%, outperforming state-of-the-art approaches. Statistical analysis is first carried out with respect to the classifiers error rates and then to evaluate the information expressed by the classifiers confusion matrices. © Springer Science+Business Media, LLC 2011

Multiple episodes of star formation in the CN15/16/17 molecular complex

We have started a campaign to identify massive star clusters inside bright molecular bubbles towards the Galactic Center. The CN15/16/17 molecular complex is the first example of our study. The region is characterized by the presence of two young clusters, DB10 and DB11, visible in the NIR, an ultra-compact HII region identified in the radio, several young stellar objects visible in the MIR, a bright diffuse nebulosity at 8\mu m coming from PAHs and sub-mm continuum emission revealing the presence of cold dust. Given its position on the sky (l=0.58, b=-0.85) and its kinematic distance of ~7.5 kpc, the region was thought to be a very massive site of star formation in proximity of the CMZ. The cluster DB11 was estimated to be as massive as 10^4 M_sun. However the region's properties were known only through photometry and its kinematic distance was very uncertain given its location at the tangential point. We aimed at better characterizing the region and assess whether it could be a site of massive star formation located close to the Galactic Center. We have obtained NTT/SofI JHKs photometry and long slit K band spectroscopy of the brightest members. We have additionally collected data in the radio, sub-mm and mid infrared, resulting in a quite different picture of the region. We have confirmed the presence of massive early B type stars and have derived a spectro-photometric distance of ~1.2 kpc, much smaller than the kinematic distance. Adopting this distance we obtain clusters masses of M(DB10) ~ 170 M_sun and M(DB11) ~ 275 M_sun. This is consistent with the absence of any O star, confirmed by the excitation/ionization status of the nebula. No HeI diffuse emission is detected in our spectroscopic observations at 2.113\mu m, which would be expected if the region was hosting more massive stars. Radio continuum measurements are also consistent with the region hosting at most early B stars.Comment: Accepted for publication in Astronomy and Astrophysics. Fig. 1 and 3 presented in reduced resolutio

Effectiveness of a short web-based film targeting parental oral health knowledge in a well-child care setting

Young children rely on their parents with respect to oral health routines. However, parental knowledge on this topic is often insufficient. Well-child care may be an excellent route to reach parents because almost all of them attend. To evaluate the effectiveness of an 8.5 min web-based film about oral health, provided by well-child care, a non-blinded quasi-experimental study was performed. Parents attending well-child care clinics in the Netherlands were assigned to an intervention (n = 88) or control group (n = 41). The control group received care as usual. We measured parental knowledge of oral health with a questionnaire (range of scores 1-12) before and directly after the intervention, and 6 months later, and assessed differences between the intervention and the control group. Parental oral health knowledge improved after watching the film: the intervention group's mean score of 11.1 (SD 1.3) was greater than the mean score of 7.1 (SD 2.0) of the control group (Cohen's d = 2.64). Scores remained higher in the intervention group 6 months after watching the film (mean 9.1, SD 1.3) than before (Cohen's d = 1.25). A web-based educational film delivered in a well-child care setting can be an effective way to address oral health and to improve parental knowledge

Body mass index and dental caries in children aged 5 to 8 years attending a dental paediatric referral practice in the Netherlands

Background Obesity and dental caries are widely-recognised problems that affect general health. The prevention of both dental caries and obesity have proven very difficult: children and their parents may need professional support to achieve behaviour change. To find out whether both dental caries and overweight in childhood can be targeted using a common risk factor approach, it is necessary to establish whether the two diseases are indeed linked. The aim of the present study was therefore to use anthropometric data obtained professionally to investigate the association between Body Mass Index and dental caries experience in children aged 5-8 years receiving treatment in a referral centre for paediatric dental care in the Netherlands. Methods Children’s dmft and dmfs scores were calculated using dental records and sociodemographic data were also extracted from these records. Dentists were trained to measure standing height and weight in a standardised way. Body Mass Index was calculated by dividing kilograms by height squared (kg/m2). Extended International (International Obesity Task Force) body mass index cut-offs were used to define ‘no overweight’ and ‘overweight’ (with the latter category including obesity). Results No statistically significant differences were found between the mean dmft or dmfs scores of the two groups (overweight and non-overweight), even after correction for the effect of the potential confounders sex, socio-economic status and ethnicity. The percentage of caries-active children in the non-overweight group was almost the same as in the overweight group. No statistically significant differences were found. Conclusions We hypothesised to find a positive association between body mass index and dental caries experience in children aged 5-8 years attending our practice. However, this study did not find a relationship of this kind. A common risk factor approach for the prevention of caries and overweight is therefore not supported by our study

Dip coating process: Silicon sheet growth development for the large-area silicon sheet task of the low-cost silicon solar array project

The technical and economic feasibility of producing solar cell quality sheet silicon by dip-coating one surface of carbonized ceramic substrates with a thin layer of large grain polycrystalline silicon was investigated. The dip-coating methods studied were directed toward a minimum cost process with the ultimate objective of producing solar cells with a conversion efficiency of 10% or greater. The technique shows excellent promise for low cost, labor-saving, scale-up potentialities and would provide an end product of sheet silicon with a rigid and strong supportive backing. An experimental dip-coating facility was designed and constructed, several substrates were successfully dip-coated with areas as large as 25 sq cm and thicknesses of 12 micron to 250 micron. There appears to be no serious limitation on the area of a substrate that could be coated. Of the various substrate materials dip-coated, mullite appears to best satisfy the requirement of the program. An inexpensive process was developed for producing mullite in the desired geometry

Trends in caries experience of adults in the Netherlands from 1995 to 2013

The Dutch National Health Care Institute, formerly CVZ/Ziekenfondsraad, asked TNO to investigate oral health in adults in the Netherlands 4 times in the period from 1995 to 2013 in order to monitor trends in oral health and, if necessary, to be able to adjust their policies accordingly. With the results of these 4 studies, the trends in caries experience of 25- up to and including 54-year-olds during the period 1995 to 2013 were established. In 1995, 2002, 2007 and 2013, the oral health of 25- up to and including 54-year-olds living in 's-Hertogenbosch was determined by means of a questionnaire and a clinical oral examination. In the period 1995-2013 a reduction in caries experience was found in both well- and less well-educated individuals. The outcomes for well-educated individuals were more favourable than those of their less well-educated peers. In 2012, then, oral health still has a socio-economic gradient. The debate on how to reach the high-risk group remains a matter of concern both for the dental profession and for politicians. In order to be able to keep a finger on the pulse monitoring of caries experience is of great importance.</p

LLiST - a new star tracker camera for tip-tilt correction at IOTA

The tip-tilt correction system at the Infrared Optical Telescope Array (IOTA) has been upgraded with a new star tracker camera. The camera features a backside-illuminated CCD chip offering doubled overall quantum efficiency and a four times higher system gain compared to the previous system. Tests carried out to characterize the new system showed a higher system gain with a lower read-out noise electron level. Shorter read-out cycle times now allow to compensate tip-tilt fluctuations so that their error imposed on visibility measurements becomes comparable to, and even smaller than, that of higher-order aberrations.Comment: To be published in "New Frontiers in Stellar Interferometry", W. A. Traub, ed., SPIE Proceedings Series, Vol. 5491, paper [5491-126]; 10 pages, 6 figures, 1 table; Latex spie class, uses packages graphicx and url; bib style spiebib; keywords: interferometry, tip-tilt correctio

Enhancement of the electronic contribution to the low temperature specific heat of Fe/Cr magnetic multilayer

We measured the low temperature specific heat of a sputtered $(Fe_{23\AA}/Cr_{12\AA})_{33}$ magnetic multilayer, as well as separate $1000\AA$ thick Fe and Cr films. Magnetoresistance and magnetization measurements on the multilayer demonstrated antiparallel coupling between the Fe layers. Using microcalorimeters made in our group, we measured the specific heat for $4<T<30 K$ and in magnetic fields up to $8 T$ for the multilayer. The low temperature electronic specific heat coefficient of the multilayer in the temperature range $4<T<14 K$ is $\gamma_{ML}=8.4 mJ/K^{2}g-at$. This is significantly larger than that measured for the Fe or Cr films (5.4 and $3.5 mJ/K^{2}mol$ respectively). No magnetic field dependence of $\gamma_{ML}$ was observed up to $8 T$. These results can be explained by a softening of the phonon modes observed in the same data and the presence of an Fe-Cr alloy phase at the interfaces.Comment: 20 pages, 5 figure