1,636 research outputs found
A Robust Semidefinite Programming Approach to the Separability Problem
We express the optimization of entanglement witnesses for arbitrary bipartite
states in terms of a class of convex optimization problems known as Robust
Semidefinite Programs (RSDP). We propose, using well known properties of RSDP,
several new sufficient tests for the separability of mixed states. Our results
are then generalized to multipartite density operators.Comment: Revised version (minor spell corrections) . 6 pages; submitted to
Physical Review
Protective effect of bronchial challenge with hypertonic saline on nocturnal asthma
Inhalation of hypertonic saline (HS) causes bronchoconstriction in asthmatic subjects. Repeated inhalation of HS leads to substantially reduced bronchoconstriction, known as the refractory period. Refractoriness due to different stimuli has also been described (cross-refractoriness). Nocturnal asthma is defined as an increase in symptoms, need for medication, airway responsiveness, and/or worsening of lung function that usually occurs from 4 to 6 am. Our objective was to determine the effect of refractoriness on nocturnal asthma. The challenge test consisted of inhalations of 4.5% saline with increasing durations until a reduction of 20% in forced expiratory volume in 1 s (FEV1) (PD20HS) or total time of 15.5 min. Twelve subjects with nocturnal asthma were challenged with HS at 16:00 and 18:00 h and FEV1 was measured at 4:00 h. One to 2 weeks later, FEV1 was determined at 16:00 and 4:00 h. LogPD20HS at 18:00 h was significantly greater than logPD20HS at 16:00 h, 0.51 ± 0.50 and 0.69 ± 0.60 mg, respectively (P = 0.0033). When subjects underwent two HS challenges in the afternoon, mean (± SD) FEV1 reduction was 206 ± 414 mL or 9.81 ± 17.42%. On the control day (without challenge in the afternoon) FEV1 reduction was 523 ± 308 mL or 22.75 ± 15.40% (P = 0.021). Baseline FEV1 values did not differ significantly between the control and study days, 2.48 ± 0.62 and 2.36 ± 0.46 L, respectively. The refractory period following HS challenges reduces the nocturnal worsening of asthma. This new concept may provide beneficial applications to asthmatic patients
Efetividade de fixação de nitrogênio de estirpes nativas de rizobio associadas a Arachis pintoi isoladas de solos de cerrado.
Was the GLE on May 17, 2012 linked with the M5.1-class flare the first in the 24th solar cycle?
On May 17, 2012 an M5.1-class flare exploded from the sun. An O-type coronal
mass ejection (CME) was also associated with this flare. There was an instant
increase in proton flux with peak at MeV, leading to S2 solar
radiation storm level. In about 20 minutes after the X-ray emission, the solar
particles reached the Earth.It was the source of the first (since December
2006) ground level enhancement (GLE) of the current solar cycle 24. The GLE was
detected by neutron monitors (NM) and other ground based detectors. Here we
present an observation by the Tupi muon telescopes (Niteroi, Brazil, , , 3 m above sea level) of the enhancement of muons at ground
level associated with this M5.1-class solar flare. The Tupi telescopes
registered a muon excess over background in the 5-min binning time
profile. The Tupi signal is studied in correlation with data obtained by
space-borne detectors (GOES, ACE), ground based neutron monitors (Oulu) and air
shower detectors (the IceTop surface component of the IceCube neutrino
observatory). We also report the observation of the muon signal possibly
associated with the CME/sheath striking the Earth magnetosphere on May 20,
2012. We show that the observed temporal correlation of the muon excess
observed by the Tupi muon telescopes with solar transient events suggests a
real physical connection between them. Our observation indicates that
combination of two factors, the low energy threshold of the Tupi muon
telescopes and the location of the Tupi experiment in the South Atlantic
Anomaly region, can be favorable in the study and detection of the solar
transient events. Our experiment provides new data complementary to other
techniques (space and ground based) in the study of solar physics.Comment: 9 pages, 10 figure
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