84 research outputs found
Multi-Gigabit Wireless data transfer at 60 GHz
In this paper we describe the status of the first prototype of the 60 GHz
wireless Multi-gigabit data transfer topology currently under development at
University of Heidelberg using IBM 130 nm SiGe HBT BiCMOS technology. The 60
GHz band is very suitable for high data rate and short distance applications as
for example needed in the HEP experments. The wireless transceiver consist of a
transmitter and a receiver. The transmitter includes an On-Off Keying (OOK)
modulator, an Local Oscillator (LO), a Power Amplifier (PA) and a BandPass
Filter (BPF). The receiver part is composed of a BandPass- Filter (BPF), a Low
Noise Amplifier (LNA), a double balanced down-convert Gilbert mixer, a Local
Oscillator (LO), then a BPF to remove the mixer introduced noise, an
Intermediate Amplifier (IF), an On-Off Keying demodulator and a limiting
amplifier. The first prototype would be able to handle a data-rate of about 3.5
Gbps over a link distance of 1 m. The first simulations of the LNA show that a
Noise Figure (NF) of 5 dB, a power gain of 21 dB at 60 GHz with a 3 dB
bandwidth of more than 20 GHz with a power consumption 11 mW are achieved.
Simulations of the PA show an output referred compression point P1dB of 19.7 dB
at 60 GHz.Comment: Proceedings of the WIT201
El aire: hábitat y medio de transmisión de microorganismos
La atmósfera no tiene una microbiota autóctona pero es un medio para la dispersión de muchos tipos de microorganismos (esporas, bacterias, virus y hongos), procedentes de otros ambientes. Algunos han creado adaptaciones especializadas que favorecen su supervivencia y permanencia. Los microorganismos dispersados por el aire tiene una gran importancia biológica y económica. Producen enfermedades en plantas, animales y humanos, causan alteración de alimentos y materiales orgánicos y contribuyen al deterioro y corrosión de monumentos y metales. La Microbiología del aire comienza en el siglo XIX, con Pasteur y Miquel que diseñaron métodos para estudiar los microorganismos en el aire y descubrir la causa de algunas enfermedades. Desde entonces numerosos investigadores han trabajado en este campo tanto en el aire exterior como en recintos cerrados. Las enfermedades transmitidas por el aire, producidas por bacterias, virus y hongos, son las respiratorias (neumonía, tosferina, tuberculosis, legionelosis, resfriado, gripe), sistémicas (meningitis, sarampión, varicela, micosis) y alérgicas
Structure function of the UV variability of Q0957+561
We present a detailed structure function analysis of the UV variability of
Q0957+561. From new optical observations, we constructed normalized structure
functions of the quasar luminosity at restframe wavelengths of 2100 and 2600
\AA. Old optical records also allow the structure function to be obtained at
2100 \AA, but 10 years ago in the observer's frame. These three structure
functions are then compared to predictions of both simple and relatively
sophisticated (incorporating two independent variable components) Poissonian
models. We do not find clear evidence of a chromatic mechanism of variability.
From the recent data, 100-d time-symmetric and 170-d time-asymmetric flares
are produced at both restframe wavelengths. Taking into account measurements of
time delays and the existence of an EUV/radio jet, reverberation is probably
the main mechanism of variability. Thus, two types of EUV/X-ray fluctuations
would be generated within or close to the jet and later reprocessed by the disc
gas in the two emission rings. The 100-d time-symmetric shots are also
responsible for most of the 2100 \AA variability detected in the old
experiment. However, there is no evidence of asymmetric shots in the old UV
variability. If reverberation is the involved mechanism of variability, this
could mean an intermittent production of high-energy asymmetric fluctuations.
The old records are also consistent with the presence of very short-lifetime
(10 d) symmetric flares, which may represent additional evidence of time
evolution. We also discuss the quasar structure that emerges from the
variability scenario.Comment: 7 pages, 4 figures. Accepted for publication in A&A (based on the
brightness records at http://arxiv.org/abs/0810.4619
Amputación Pirogoff modificada aplicada a la cirugía oncológica del pie
Los sarcomas óseos y de tejidos blandos del pie son infrecuentes, representando menos del 10% de todos los sarcomas de la extremidad inferior. El tratamiento más frecuente de los sarcomas del pie es la amputación por debajo de la rodilla, debido a la imposibilidad de conseguir márgenes amplios, pero en determinados casos de tumores del antepié se puede optar por una amputación parcial del pie con margen amplio. Se presenta una serie de tres casos de amputación de Pirogoff modificada aplicada a la resección oncológica tumoral. La amputación de Pirogoff consiste en una artrodesis calcaneotibial con resección del astrágalo, rotando el calcáneo 90°. La modificación de la técnica de amputación del Pirogoff, en la que se conservan ambos maléolos con escisión de la carilla articular favorece la estabilidad en el plano lateral y ayuda a una más rápida artrodesis. Es muy importante mantener los principios oncológicos de la resección tumoral.Bone and soft-tissue sarcomata of the foot are infrequent neoplasms, representing less than 10% of all lower limb sarcomata. The most frequent therapeutic measure for foot sarcomata is amputation below the knee, due to the difficulty to achieve ample (onco-)-surgical margins, yet in a number of cases of forefoottumours there is an option for partial foot amputation with ample surgical margins. We report a series of three cases of modified Pirogoff's amputation as applied to oncosurgical tumour resection. Pirogoff's amputation is a calcaneo-tibial arthrodesis with resection of the talus and 90° rotation of the calcaneus. The here reported modification of the Pirogoff amputation, in which both malleoli are preserved yet with excision of the articular surface, favours lateral-plane stability and promotes a quicker arthrodesis. It is highly important to observe and maintain the oncologic surgery principles for tumour resection
Time delay of SBS 0909+532
The time delays between the components of a lensed quasar are basic tools to
analyze the expansion of the Universe and the structure of the main lens galaxy
halo. In this paper, we focus on the variability and time delay of the double
system SBS 0909+532A,B as well as the time behaviour of the field stars. We use
VR optical observations of SBS 0909+532A,B and the field stars in 2003. The
frames were taken at Calar Alto, Maidanak and Wise observatories, and the VR
light curves of the field stars and quasar components are derived from aperture
and point-spread function fitting methods. We measure the R-band time delay of
the system from the chi-square and dispersion techniques and 1000 synthetic
light curves based on the observed records. One nearby field star (SBS
0909+532c) is found to be variable, and the other two nearby field stars are
non-variable sources. With respect to the quasar components, the R-band records
seem more reliable and are more densely populated than the V-band ones. The
observed R-band fluctuations permit a pre-conditioned measurement of the time
delay. From the chi-square minimization, if we assume that the quasar emission
is observed first in B and afterwards in A (in agreement with basic
observations of the system and the corresponding predictions), we obtain a
delay of - 45 (+ 1)/(- 11) days (95% confidence interval). The dispersion
technique leads to a similar delay range. A by-product of the analysis is the
determination of a totally corrected flux ratio in the R band (corrected by the
time delay and the contamination due to the galaxy light). Our 95% measurement
of this ratio (0.575 +/- 0.014 mag) is in excellent agreement with previous
results from contaminated fluxes at the same time of observation.Comment: 26 pages, 15 figures, Astronomy and Astrophysics (see also
http://www.astro.ulg.ac.be/RPub/Colloques/JENAM/proceedings/proceedings.html
- Quasars Section
First robotic monitoring of a lensed quasar: intrinsic variability of SBS 0909+532
To go into the details about the variability of the double quasar SBS
0909+532, we designed a monitoring programme with the 2 m Liverpool Robotic
Telescope in the r Sloan filter, spanning 1.5 years from 2005 January to 2006
June. The r-band light curves of the A and B components, several
cross-correlation techniques and a large number of simulations (synthetic light
curves) lead to a robust delay of 49 +/- 6 days (1-sigma interval) that agrees
with our previous results (the B component is leading). Once the time delay and
the magnitude offset are known, the magnitude- and time-shifted light curve of
image A is subtracted from the light curve of image B. This difference light
curve of SBS 0909+532 is consistent with zero, so any possible extrinsic signal
must be very weak, i.e., the observed variability in A and B is basically due
to observational noise and intrinsic signal. We then make the combined light
curve and analyse its statistical properties (structure functions). The
structure function of the intrinsic luminosity is fitted to predictions of
simple models of two physical scenarios: accretion disc instabilities and
nuclear starbursts. Although no simple model is able to accurately reproduce
the observed trend, symmetric triangular flares in an accretion disc seems to
be the best option to account for it.Comment: 27 pages, 9 figures and 2 tables (including information on the
robotic monitoring and the final fluxes). Accepted for publication in New
Astronom
Molecular characterization of a fungal gene paralogue of the penicillin penDE gene of Penicillium chrysogenum
<p>Abstract</p> <p>Background</p> <p><it>Penicillium chrysogenum </it>converts isopenicillin N (IPN) into hydrophobic penicillins by means of the peroxisomal IPN acyltransferase (IAT), which is encoded by the <it>penDE </it>gene. <it>In silico </it>analysis of the <it>P. chrysogenum </it>genome revealed the presence of a gene, Pc13g09140, initially described as paralogue of the IAT-encoding <it>penDE </it>gene. We have termed this gene <it>ial </it>because it encodes a protein with high similarity to IAT (IAL for IAT-Like). We have conducted an investigation to characterize the <it>ial </it>gene and to determine the role of the IAL protein in the penicillin biosynthetic pathway.</p> <p>Results</p> <p>The IAL contains motifs characteristic of the IAT such as the processing site, but lacks the peroxisomal targeting sequence ARL. Null <it>ial </it>mutants and overexpressing strains indicated that IAL lacks acyltransferase (penicillin biosynthetic) and amidohydrolase (6-APA forming) activities <it>in vivo</it>. When the canonical ARL motif (leading to peroxisomal targeting) was added to the C-terminus of the IAL protein (IAL<sup>ARL</sup>) by site-directed mutagenesis, no penicillin biosynthetic activity was detected. Since the IAT is only active after an accurate self-processing of the preprotein into α and β subunits, self-processing of the IAL was tested in <it>Escherichia coli</it>. Overexpression experiments and SDS-PAGE analysis revealed that IAL is also self-processed in two subunits, but despite the correct processing, the enzyme remained inactive <it>in vitro</it>.</p> <p>Conclusion</p> <p>No activity related to the penicillin biosynthesis was detected for the IAL. Sequence comparison among the <it>P. chrysogenum </it>IAL, the <it>A. nidulans </it>IAL homologue and the IAT, revealed that the lack of enzyme activity seems to be due to an alteration of the essential Ser309 in the thioesterase active site. Homologues of the <it>ial </it>gene have been found in many other ascomycetes, including non-penicillin producers. Our data suggest that like in <it>A. nidulans</it>, the <it>ial </it>and <it>penDE </it>genes might have been formed from a single ancestral gene that became duplicated during evolution, although a separate evolutive origin for the <it>ial </it>and <it>penDE </it>genes, is also discussed.</p
Time delay between images of the lensed quasar UM673
We study brightness variations in the double lensed quasar UM673 (Q0142-100)
with the aim of measuring the time delay between its two images. In the paper
we combine our previously published observational data of UM673 obtained during
the 2003 - 2005 seasons at the Maidanak Observatory with archival and recently
observed Maidanak and CTIO UM673 data. We analyze the V, R and I-band light
curves of the A and B images of UM673, which cover ten observational seasons
from August 2001 to November 2010. We also analyze the time evolution of the
difference in magnitudes between images A and B of UM673 over more than ten
years. We find that the quasar exhibits both short-term (with amplitude of \sim
0.1 mag in the R band) and high-amplitude (\sim 0.3 mag) long-term variability
on timescales of about several months and several years, respectively. These
brightness variations are used to constrain the time delay between the images
of UM673. From cross-correlation analysis of the A and B quasar light curves
and error analysis we measure the mean time delay and its error of 89 \pm11
days. Given the input time delay of 88 days, the most probable value of the
delay that can be recovered from light curves with the same statistical
properties as the observed R-band light curves of UM673 is 95{+5/-16}{+14/-29}
days (68 and 95 % confidence intervals). Analysis of the V - I color variations
and V, R and I-band magnitude differences of the quasar images does not show
clear evidence of the microlensing variations between 1998 and 2010.Comment: Submitted to A&A, 11 pages, 9 figure
Exploring the theoretical foundations of visual art programmes for people living with dementia
Despite the growing international innovations for visual arts interventions in dementia care, limited attention has been paid to their theoretical basis. In response, this paper explores how and why visual art interventions in dementia care influence changes in outcomes. The theory building process consists of a realist review of primary research on visual art programmes. This aims to uncover what works, for whom, how, why and in what circumstances. We undertook a qualitative exploration of stakeholder perspectives of art programmes, and then synthesised these two pieces of work alongside broader theory to produce a conceptual framework for intervention development, further research and practice. This suggests effective programmes are realised through essential attributes of two key conditions (provocative and stimulating aesthetic experience; dynamic and responsive artistic practice). These conditions are important for cognitive, social and individual responses, leading to benefits for people with early to more advanced dementia. This work represents a starting point at identifying theories of change for arts interventions, and for further research to critically examine, refine and strengthen the evidence base for the arts in dementia care. Understanding the theoretical basis of interventions is important for service development, evaluation and implementation
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