428 research outputs found
Solar total irradiance in cycle 23
The apparently unusual behaviour of the TSI during the most recent minimum of
solar activity has been interpreted as evidence against solar surface magnetism
as the main driver of the secular change in the TSI. We test claims that the
evolution of the solar surface magnetic field does not reproduce the observed
TSI in cycle 23. We use sensitive, 60-minute averaged MDI magnetograms and
quasi-simultaneous continuum images as an input to our SATIRE-S model and
calculate the TSI variation over cycle 23, sampled roughly twice-monthly. The
computed TSI is then compared to the PMOD composite of TSI measurements and to
the data from two individual instruments, SORCE/TIM and UARS/ACRIM II, that
monitored the TSI during the declining phase of cycle 23 and over the previous
minimum in 1996, respectively. Excellent agreement is found between the trends
shown by the model and almost all sets of measurements. The only exception is
the early, i.e. 1996 to 1998, PMOD data. Whereas the agreement between the
model and the PMOD composite over the period 1999-2009 is almost perfect, the
modelled TSI shows a steeper increase between 1996 and 1999 than implied by the
PMOD composite. On the other hand, the steeper trend in the model agrees
remarkably well with the ACRIM II data. A closer look at the VIRGO data, that
make the basis of the PMOD composite after 1996, reveals that only one of the
two VIRGO instruments, the PMO6V, shows the shallower trend present in the
composite, whereas the DIARAD measurements indicate a steeper trend. We
conclude that (1) the sensitivity changes of the PMO6V radiometers within VIRGO
during the first two years have very likely not been correctly evaluated, and
that (2) the TSI variations over cycle 23 and the change in the TSI levels
between the minima in 1996 and 2008 are consistent with the solar surface
magnetism mechanism
Improving the lens design and performance of a contemporary electromagnetic shock wave lithotripter.
The efficiency of shock wave lithotripsy (SWL), a noninvasive first-line therapy for millions of nephrolithiasis patients, has not improved substantially in the past two decades, especially in regard to stone clearance. Here, we report a new acoustic lens design for a contemporary electromagnetic (EM) shock wave lithotripter, based on recently acquired knowledge of the key lithotripter field characteristics that correlate with efficient and safe SWL. The new lens design addresses concomitantly three fundamental drawbacks in EM lithotripters, namely, narrow focal width, nonidealized pulse profile, and significant misalignment in acoustic focus and cavitation activities with the target stone at high output settings. Key design features and performance of the new lens were evaluated using model calculations and experimental measurements against the original lens under comparable acoustic pulse energy (E+) of 40 mJ. The -6-dB focal width of the new lens was enhanced from 7.4 to 11 mm at this energy level, and peak pressure (41 MPa) and maximum cavitation activity were both realigned to be within 5 mm of the lithotripter focus. Stone comminution produced by the new lens was either statistically improved or similar to that of the original lens under various in vitro test conditions and was significantly improved in vivo in a swine model (89% vs. 54%, P = 0.01), and tissue injury was minimal using a clinical treatment protocol. The general principle and associated techniques described in this work can be applied to design improvement of all EM lithotripters
How to use magnetic field information for coronal loop identification?
The structure of the solar corona is dominated by the magnetic field because
the magnetic pressure is about four orders of magnitude higher than the plasma
pressure. Due to the high conductivity the emitting coronal plasma (visible
e.g. in SOHO/EIT) outlines the magnetic field lines. The gradient of the
emitting plasma structures is significantly lower parallel to the magnetic
field lines than in the perpendicular direction. Consequently information
regarding the coronal magnetic field can be used for the interpretation of
coronal plasma structures. We extrapolate the coronal magnetic field from
photospheric magnetic field measurements into the corona. The extrapolation
method depends on assumptions regarding coronal currents, e.g. potential fields
(current free) or force-free fields (current parallel to magnetic field). As a
next step we project the reconstructed 3D magnetic field lines on an EIT-image
and compare with the emitting plasma structures. Coronal loops are identified
as closed magnetic field lines with a high emissivity in EIT and a small
gradient of the emissivity along the magnetic field.Comment: 14 pages, 3 figure
Computed tomography imaging of the coronary sinus: A valuable preoperative screen for resynchronization therapy?
Randomized controlled trial comparing three different modalities of lithotrites for intracorporeal lithotripsy in pcnl
Purpose: To compare the efficiency (stone fragmentation and removal time) and complications of three models of intracorporeal lithotripters in percutaneous nephrolithotomy (PCNL). Materials and Methods: Prospective, randomized controlled trial at nine centers in the North America from 2009 to 2016. Patients were randomized to one of three lithotripter devices: the Cyberwand, a dual probe ultrasonic device; the Swiss Lithoclast Select, a combination pneumatic and ultrasonic device; and the StoneBreaker, a portable pneumatic device powered by CO2 cartridges. Since the StoneBreaker lacks an ultrasonic component, it was used with the LUS‐II ultrasonic lithotripter to allow fair comparison with combination devices. Results: 270 patients were enrolled, 69 were excluded after randomization. 201 patients completed the study: 71 in the Cyberwand group, 66 in the Lithoclast Select, and 64 in the StoneBreaker group. The baseline patient characteristics of the three groups were similar. Mean stone surface area was smaller in the StoneBreaker group at 407.8mm2 vs 577.5mm2 (Lithoclast Select) and 627.9mm2 (Cyberwand). The stone clearance rate was slowest in the StoneBreaker group at 24.0 mm2/min vs 28.9 mm2/min and 32.3 mm2/min in the Lithoclast Select and Cyberwand groups respectively. After statistically adjusting for the smaller mean stone size in the StoneBreaker group, there was no difference in the stone clearance rate among the three groups (p=0.249). Secondary outcomes, including complications and stone free rates, were similar between the groups. Conclusions: The Cyberwand, Lithoclast Select, and the StoneBreaker lithotripters have similar adjusted stone clearance rates in PCNL for stones > 2cm. The safety and efficacy of these devices are comparable
Collective labor relations and juridification: a marriage proposal
Contributing to debates over relations between the collective and juridified regulation of labor, this article analyzes a rich case study in the Israeli construction sector to claim that juridification can spur unions and employers’ associations to initiate strategic and inclusive change. By subsuming processes of juridification into traditional IR frameworks and embracing its logic and practices, the corporatist social partners broaden the relevance of collective labor relations to workers otherwise excluded from direct union representation. In this way, while not increasing union density or improving wages, these ‘traditional’ IR actors reassert their monopolistic control over worker and employer representation, as well as over the sectoral labor market
Junkie love : romance and addiction on the big screen
This article investigates the filmic construction of two disparate but intertwining cultural practices: those engaging in the life-affirming rituals of romantic love and those performing the potentially self-destructive rituals of hard drug consumption. Discussing a number of key feature films from the (mini) genre “junkie love”, it aims to show what happens when elements of mainstream romantic drama merge with the horror conventions of the heroin addiction film. Drawing amongst others on Murray Smith’s theory of “levels of [spectator] engagement” and Greg Smith’s concept of the “emotion system”, the article concludes that junkie love films, using tropes of the romantic tragedy in the tradition of Romeo and Juliet, present a more complex and nuanced approach to drug addicts than the predominantly condemnatory media coverage—one that arguably invites the spectator’s understanding and compassion
Metabolic diagnosis and medical prevention of calcium nephrolithiasis and its systemic manifestations: a consensus statement
Background: Recently published guidelines on the medical management of renal stone disease did not address relevant topics in the field of idiopathic calcium nephrolithiasis, which are important also for clinical research. Design: A steering committee identified 27 questions, which were proposed to a faculty of 44 experts in nephrolithiasis and allied fields. A systematic review of the literature was conducted and 5216 potentially relevant articles were selected; from these, 407 articles were deemed to provide useful scientific information. The Faculty, divided into working groups, analysed the relevant literature. Preliminary statements developed by each group were exhaustively discussed in plenary sessions and approved. Results: Statements were developed to inform clinicians on the identification of secondary forms of calcium nephrolithiasis and systemic complications; on the definition of idiopathic calcium nephrolithiasis; on the use of urinary tests of crystallization and of surgical observations during stone treatment in the management of these patients; on the identification of patients warranting preventive measures; on the role of fluid and nutritional measures and of drugs to prevent recurrent episodes of stones; and finally, on the cooperation between the urologist and nephrologist in the renal stone patients. Conclusions: This document has addressed idiopathic calcium nephrolithiasis from the perspective of a disease that can associate with systemic disorders, emphasizing the interplay needed between urologists and nephrologists. It is complementary to the American Urological Association and European Association of Urology guidelines. Future areas for research are identified
Variability of Sun-like stars: reproducing observed photometric trends
The Sun and stars with low magnetic activity levels, become photometrically
brighter when their activity increases. Magnetically more active stars display
the opposite behaviour and get fainter when their activity increases.
We reproduce the observed photometric trends in stellar variations with a
model that treats stars as hypothetical Suns with coverage by magnetic features
different from that of the Sun.
The presented model attributes the variability of stellar spectra to the
imbalance between the contributions from different components of the solar
atmosphere, such as dark starspots and bright faculae. A stellar spectrum is
calculated from spectra of the individual components, by weighting them with
corresponding disc area coverages. The latter are obtained by extrapolating the
solar dependences of spot and facular disc area coverages on chromospheric
activity to stars with different levels of mean chromospheric activity.
We have found that the contribution by starspots to the variability increases
faster with chromospheric activity than the facular contribution. This causes
the transition from faculae-dominated variability and direct
activity--brightness correlation to spot-dominated variability and inverse
activity--brightness correlation with increasing chromospheric activity level.
We have shown that the regime of the variability also depends on the angle
between the stellar rotation axis and the line-of-sight and on the latitudinal
distribution of active regions on the stellar surface. Our model can be used as
a tool to extrapolate the observed photometric variability of the Sun to
Sun-like stars at different activity levels, which makes possible the direct
comparison between solar and stellar irradiance data.Comment: 20 pages, 16 figures, accepted for publication in
Astronomy&Astrophysic
How do stone attenuation and skin-to-stone distance in computed tomography influence the performance of shock wave lithotripsy in ureteral stone disease?
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