An analysis of automatic teller machine usage by older adults: a structured interview approach

Sex differences in the activity of aromatase cytochrome P450 (CYP19) in the rat brain have been reported during pre- and postnatal development. It is unclear, however, whether these differences are reflected by corresponding differences in specific mRNA levels. To address this question, we have examined aromatase mRNA levels in specific regions of male and female rat brains by means of in situ hybridization (ISH). At prenatal stages of development, i.e. at gestational day 18 (GD18) and GD20, aromatase mRNA was detected in several preoptic, hypothalamic and limbic brain regions. Semiquantitative analysis of aromatase mRNA did not reveal sex differences in any of these regions. In contrast, clear-cut sex differences were determined at postnatal day (PN) 2; male animals expressed significantly more aromatase mRNA in the bed nucleus of stria terminalis (BST) and the sexually dimorphic nucleus of the preoptic area (SDN). Smaller but still significant differences (females > males) were obtained in the medial preoptic area (MPO). At PN6, sex differences of aromatase mRNA signals (males > females) were still present in the BST, but were no longer detectable in the SDN and the MPO. At PN15 and in adult animals, aromatase mRNA levels were similar in BST and medical amygdaloid nucleus of male and female rats. Since aromatase mRNA expression decreases during postnatal development, no ISH signals could be detected anymore in MPO, SDN and ventromedial hypothalamic nucleus. Our results are consistent with the concept that differential regulation of aromatase mRNA expression might be important for the establishment of different neuronal circuitry in male and female animals.     

Diagnosis of transfusion-associated graft-versus-host disease by polymerase chain reaction in fludarabine-treated B-chronic lymphocytic leukaemia

Transfusion-associated graft-versus-host disease (TA-GVHD), has rarely been reported associated with B-chronic lymphocytic leukaemia (B-CLL). We report a patient diagnosed with B-CLL, previously treated with fludarabine, who developed TA-GVHD after being transfused during surgery for splenectomy. Diagnosis was confirmed by polymerase chain reaction (PCR) detection of donor DNA in the patient, by amplification of Y-chromosome sequence and analysis of minisatellite polymorphisms. B-CLL patients treated with fludarabine appear to be at risk for TA-GVHD and should be regarded as candidates for transfusions with irradiated blood products. This case illustrates that PCR is a rapid technique for the early diagnosis of TA-GVHD.     

Modeling the flow behavior of a medium carbon microalloyed steel under hot working conditions

The constitutive equations for the flow behavior of a commercial 0.34 pct C-1.5 pct Mn-0.7 pct Si-0.083 pct V-0.018 pct Ti microalloyed steel were determined. For this purpose, uniaxial hot compression tests were carried out over a wide range of strain rates (10⁻⁴ to 10 s⁻¹) and temperatures (1123 to 1423 K). In combination with models developed in the literature, the experimental results permit the flow stress of the present steel to be predicted within ± 5 pct. It is shown that the classical constitutive equations must be modified to take the grain size into account, particularly when the latter is below 30 μm.     

Multi-approach back-analysis of a roof bed collapse in a mining room excavated in stratified rock

Roof bed deformation mechanics is a complex topic in mining practice. There are a number of empirical, analytical and numerical techniques that can be used to analyze and design underground excavations in stratified rock masses. Each has particular drawbacks, however, so the use of just one approach in order to obtain consistent and economic designs is not practical. To deepen understanding of this topic, it is useful to study real failure in mines. In this paper we describe how a roof bed failure in an underground mine, excavated in a stratified rock mass, was back-analyzed using different approaches, namely, the empirical stability graph method, the analytical voussoir techniques, and the numerical discrete element method. The study enabled us to better understand the conditions of failure and to define the most significant parameters affecting the failure. It has also been shown how relaxation or loss of confinement stress can play an important role in roof bed deformation.     

Spatial Imaging of Charge Transport in Germanium at Low Temperature

The purpose of this experiment is to observe the oblique propagation of electrons through germanium by exciting a point source of charge carriers with a focused laser pulse on one face of a germanium crystal. After the electrons are drifted through the crystal by a uniform electric field, the pattern of charge density arriving on the opposite face is mapped and used to reconstruct the trajectories of the electrons. These measurements will verify in detail the Monte Carlo analysis utilized in the Cryogenic Dark Matter Search to model the transport of charge carriers in high-purity germanium detectors, including both oblique electron propagation and inter-valley scattering.     

An extension of the noncommutative Bergman’s ring with a large number of noninvertible elements

For a prime number \(p\) , Bergman (Israel J Math 18:257–277, 1974) established that \(\mathrm {End}(\mathbb {Z}_{p} \times \mathbb {Z}_{p^{2}})\) is a semilocal ring with \(p^{5}\) elements that cannot be embedded in matrices over any commutative ring. In an earlier paper Climent et al. (Appl Algebra Eng Commun Comput 22(2):91–108, 2011), the authors presented an efficient implementation of this ring, and introduced a key exchange protocol based on it. This protocol was cryptanalyzed by Kamal and Youssef (Appl Algebra Eng Commun Comput 23(3–4):143–149, 2012) using the invertibility of most elements in this ring. In this paper we introduce an extension of Bergman’s ring, in which only a negligible fraction of elements are invertible, and propose to consider a key exchange protocol over this ring.     

Directional Estimation of Block-Fading MIMO Channels Using Spherical Harmonics Expansion and Tensor Analysis

The well-known benefits of multiple input multiple output (MIMO) wireless communication systems suppose an efficient use of spatial diversity at both the transmitter and receiver. An important and not well-explored path toward improving MIMO system performance using spatial diversity takes into account the interactions among the antennas and the (physical) propagation medium. In this work, spherical harmonics and tensor analysis are originally combined into the problem of MIMO channel modeling and estimation. The use of spherical harmonics allows to represent the antenna radiation patterns in terms of coefficients of an expansion of spatially orthogonal functions, thus decoupling the transmit and receive antenna array responses from the physical propagation medium. Assuming a single-scattering propagation scenario driven by a finite number of specular multipaths, the parallel factor model is used to decompose the spherical modes of the MIMO channel into a sum of rank-one spherical mode tensors, whose dimensions are transmit modes, receive modes, and time. Then, we extend the tensor modeling framework to double scattering channels by resorting to the PARATUCK model that captures the interactions between multiple-scattering clusters. Capitalizing on the structure of these tensor models, we derive tensor-based alternating least squares algorithms for estimating directional MIMO channels in the spherical harmonics domain, from which the directions of arrival and directions of departure are extracted by means of a MUSIC-based method. Simulation results are provided to assess the performance of the proposed algorithms in selected system configurations. Our results also show the impact of the spherical expansion order on the accuracy of DoD/DoA estimates using the proposed algorithms.     

An energy efficient joint localization and synchronization solution for wireless sensor networks using unmanned aerial vehicle

Localization and synchronization are fundamental services for many applications in wireless sensor networks (WSNs), since it is often required to know the sensor nodes’ position and global time to relate a given event detection to a specific location and time. However, the localization and synchronization tasks are often performed after the sensor nodes’ deployment on the sensor field. Since manual configuration of sensor nodes is usually an impractical activity, it is necessary to rely on specific algorithms to solve both localization and clock synchronization problems of sensor nodes. With this in mind, in this work we propose a joint solution for the problem of 3D localization and time synchronization in WSNs using an unmanned aerial vehicle (UAV). A UAV equipped with GPS flies over the sensor field broadcasting its geographical position. Therefore, sensor nodes are able to estimate their geographical position and global time without the need of equipping them with a GPS device. Through simulation experiments, we show that our proposed joint solution reduces time synchronization and localization errors as well as energy consumption when compared to solutions found in the literature.     

Corrosion resistance of directionally solidified Al–6Cu–1Si and Al–8Cu–3Si alloys castings

The aim of this article is to compare the electrochemical corrosion resistance of two as-cast Al–6 wt.% Cu–1 wt.% Si and Al–8 wt.% Cu–3 wt.% Si alloys considering both the solutes macrosegregation profiles and the scale of the microstructure dendritic arrays. A water-cooled unidirectional solidification system was used to obtain the as-cast samples. Electrochemical impedance spectroscopy (EIS) and potentiodynamic anodic polarization techniques were used to analyze the corrosion resistance in a 0.5 M NaCl solution at 25 °C. It was found that the Al–8Cu–3Si alloy has better electrochemical corrosion resistance than the Al–6Cu–1Si alloy for any position along the casting length. At the castings regions where the Cu inverse profile prevailed (up to about 10 mm from the castings surface) the corrosion current density decreased up to 2.5 times with the decrease in the secondary dendrite arm spacing.     

Correlated Postfiltering and Mutual Information in Pseudoanechoic Model Based Blind Source Separation

In a recent publication the pseudoanechoic mixing model for closely spaced microphones was proposed and a blind audio sources separation algorithm based on this model was developed. This method uses frequency-domain independent component analysis to identify the mixing parameters. These parameters are used to synthesize the separation matrices, and then a time-frequency Wiener postfilter to improve the separation is applied. In this contribution, key aspects of the separation algorithm are optimized with two novel methods. A deeper analysis of the working principles of the Wiener postfilter is presented, which gives an insight in its reverberation reduction capabilities. Also a variation of this postfilter to improve the performance using the information of previous frames is introduced. The basic method uses a fixed central frequency bin for the estimation of the mixture parameters. In this contribution an automatic selection of the central bin, based in the information of the separability of the sources, is introduced. The improvements obtained through these methods are evaluated in an automatic speech recognition task and with the PESQ objective quality measure. The results show an increased robustness and stability of the proposed method, enhancing the separation quality and improving the speech recognition rate of an automatic speech recognition system.