Magnetic behavior of nanocrystalline ErCo2

We have investigated the magnetic behavior of the nanocrystalline form of a well-known Laves phase compound, ErCo2 - the bulk form of which has been known to undergo an interesting first-order ferrimagnetic ordering near 32 K - synthesized by high-energy ball-milling. It is found that, in these nanocrystallites, Co exhibits ferromagnetic order at room temperature as inferred from the magnetization data. However, the magnetic transition temperature for Er sublattice remains essentially unaffected as though the (Er)4f-Co(3d) coupling is weak on Er magnetism. The net magnetic moment as measured at high fields, sat at 120 kOe, is significantly reduced with respect to that for the bulk in the ferrimagnetically ordered state and possible reasons are outlined. We have also compared the magnetocaloric behavior for the bulk and the nano particles.Comment: JPCM, in pres

The Discovery of a Molecular Complex in the Tidal Arms near NGC 3077

We present the discovery of a giant molecular complex (r=350 pc, M_ vir=10^7 M_sun) in the tidal arms south-east of NGC 3077, a member of the M 81 triplet. The complex is clearly detected in the 12CO (J=1-0) transition at five independent positions. The position relative to NGC 3077, the systemic velocity (v_hel=14km/s) and the cloud averaged line width (15km/s) indicate that the object is not related to Galactic cirrus but is extragalactic. The tidal HI arm where the molecular complex is located has an total HI mass of M_HI=3x10^8 M_sun. This tidal material was presumably stripped off the outer parts of NGC 3077 during the closest encounter with M 81, about 3x10^8 years ago. After the complex detected along a torn-out spiral arm of M 81 by Brouillet et al., it is the second of its kind reported so far. Based on published optical observations, we have no evidence for on--going star formation in the newly detected molecular complex. Since the system has all the ingredients to form stars in the future, we speculate that it might eventually resemble the young dwarf galaxies in the M 81 group.Comment: 12 pages (including 3 figures), accepted for publication in the ApJ Letter

Observation of a Griffiths-like phase in the paramagnetic regime of ErCo_2

A systematic x-ray magnetic circular dichroism study of the paramagnetic phase of ErCo2 has recently allowed to identify the inversion of the net magnetization of the Co net moment with respect to the applied field well above the ferrimagnetic ordering temperature, Tc. The study of small angle neutron scattering measurements has also shown the presence of short range order correlations in the same temperature region. This phenomenon, which we have denoted parimagnetism, may be related with the onset of a Griffiths-like phase in paramagnetic ErCo2. We have measured ac susceptibility on ErCo2 as a function of temperature, applied field, and excitation frequency. Several characteristics shared by systems showing a Griffiths phase are present in ErCo2, namely the formation of ferromagnetic clusters in the disordered phase, the loss of analyticity of the magnetic susceptibility and its extreme sensitivity to an applied magnetic field. The paramagnetic susceptibility allows to establish that the magnetic clusters are only formed by Co moments as well as the intrinsic nature of those Co moments

Powerful H2_2 Line-cooling in Stephan's Quintet : I - Mapping the Significant Cooling Pathways in Group-wide Shocks

We present results from the mid-infrared spectral mapping of Stephan's Quintet using the Spitzer Space Telescope. A 1000 km/s collision has produced a group-wide shock and for the first time the large-scale distribution of warm molecular hydrogen emission is revealed, as well as its close association with known shock structures. In the main shock region alone we find 5.0 $\times10^{8}$ M$_{\odot}$ of warm H$_2$ spread over $\sim$ 480 kpc$^2$ and additionally report the discovery of a second major shock-excited H$_2$ feature. This brings the total H$_2$ line luminosity of the group in excess of 10$^42$ erg/s. In the main shock, the H$_2$ line luminosity exceeds, by a factor of three, the X-ray luminosity from the hot shocked gas, confirming that the H$_2$-cooling pathway dominates over the X-ray. [Si II]34.82$\mu$m emission, detected at a luminosity of 1/10th of that of the H$_2$, appears to trace the group-wide shock closely and in addition, we detect weak [FeII]25.99$\mu$m emission from the most X-ray luminous part of the shock. Comparison with shock models reveals that this emission is consistent with regions of fast shocks (100 < $V_{s}$ < 300 km/s) experiencing depletion of iron and silicon onto dust grains. Star formation in the shock (as traced via ionic lines, PAH and dust emission) appears in the intruder galaxy, but most strikingly at either end of the radio shock. The shock ridge itself shows little star formation, consistent with a model in which the tremendous H$_{2}$ power is driven by turbulent energy transfer from motions in a post-shocked layer. The significance of the molecular hydrogen lines over other measured sources of cooling in fast galaxy-scale shocks may have crucial implications for the cooling of gas in the assembly of the first galaxies.Comment: 23 pages, 15 figures, Accepted to Ap

Learning frequent behaviors patterns in intelligent environments for attentiveness level

Nowadays, when it comes to achieving goals in business environments or educational environments, the performance successfully has an important role in performing a task. However, this performance can be affected by several factors. One of the most common is the lack of attention. The individual’s attention in performing a task can be determinant for the final quality or even at the task’s conclusion. In this paper is intended to design a solution that can reduce or even eliminate the lack of attention on performing a task. The idea consist on develop an architecture that capture the user behavior through the mouse and keyboard usage. Furthermore, the system will analyze how the devices are used.This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013.info:eu-repo/semantics/publishedVersio

The Molecule-Rich Tail of the Peculiar Galaxy NGC 2782 (Arp 215)

We present the first detection of a large quantity of molecular gas in the extended tail of an interacting galaxy. Using the NRAO 12m telescope, we have detected CO (1 - 0) at five locations in the eastern tail of the peculiar starburst galaxy NGC 2782. The CO velocities and narrow (FWHM = 50 km/s) line widths in these positions agree with those seen in HI, confirming that the molecular gas is indeed associated with the tail rather than the main disk. As noted previously, the gas in this tail has an apparent `counter-rotation' compared to gas in the core of the galaxy, probably because the tails do not lie in the same plane as the disk. Assuming the standard Galactic conversion N(H2)/I(CO) factor, these observations indicate a total molecular gas mass of 6 X 10**8 M(sun) in this tail. This may be an underestimate of the total H2 mass if the gas is metal-poor. This molecular gas mass, and the implied H2/HI mass ratio of 0.6, are higher than that found in many dwarf irregular galaxies. Comparison with an available H-alpha map of this galaxy, however, shows that the rate of star formation in this feature is extremely low relative to the available molecular gas, compared to L(H-alpha)/M(H2) values for both spiral and irregular galaxies. Thus the timescale for depletion of the gas in this feature is very long.Comment: 19 pages, 6 figures, Latex. To appear in the Astronomical Journa

Development of a Real-Time, Simple and High-Accuracy Fall Detection System for Elderly Using 3-DOF Accelerometers

© 2018, King Fahd University of Petroleum & Minerals. Falls represent a major problem for the elderly people aged 60 or above. There are many monitoring systems which are currently available to detect the fall. However, there is a great need to propose a system which is of optimal effectiveness. In this paper, we propose to develop a low-cost fall detection system to precisely detect an event when an elderly person accidentally falls. The fall detection algorithm compares the acceleration with lower fall threshold and upper fall threshold values to accurately detect a fall event. The post-fall recognition module is the combination of posture recognition and vertical velocity estimation that has been added to our proposed method to enhance the performance and accuracy. In case of a fall, our device will transmit the location information to the contacts instantly via SMS and voice call. A smartphone application will ensure that the notifications are delivered to the elderly person’s relatives so that medical attention can be provided with minimal delay. The system was tested by volunteers and achieved 100% sensitivity and accuracy. This was confirmed by testing with public datasets and it also achieved the same percentage in sensitivity and accuracy as in our recorded datasets