770 research outputs found
Two-dimensional frustrated spin systems in high magnetic fields
We discuss our numerical results on the properties of the S = 1/2 frustrated
J1-J2 Heisenberg model on a square lattice as a function of temperature and
frustration angle phi = atan(J2/J1) in an applied magnetic field. We cover the
full phase diagram of the model in the range -pi <= phi <= pi. The discussion
includes the parameter dependence of the saturation field itself, and addresses
the instabilities associated with it. We also discuss the magnetocaloric effect
of the model and show how it can be used to uniquely determine the effective
interaction constants of the compounds which were investigated experimentally.Comment: 4 pages, 5 figures, proceedings of RHMF 200
Giant nonlinear conduction and thyristor-like negative derivative resistance in BaIrO3 single crystals
We synthesized single-crystalline samples of monoclinic BaIrO3 using a molten
flux method, and measured their magnetization, resistivity, Seebeck coefficient
and nonlinear voltage-current characteristics. The magnetization rapidly
increases below a ferromagnetic transition temperature TC of 180 K, where the
resistivity concomitantly shows a hump-type anomaly, followed by a sharp
increase below 30 K. The Seebeck coefficient suddenly increases below TC, and
shows linear temperature dependence below 50 K. A most striking feature of this
compound is that the anomalously giant nonlinear conduction is observed below
30 K, where a small current density of 20 A/cm2 dramatically suppresses the
sharp increase in resistivity to induce a metallic conduction down to 4 K.Comment: 10 pages, 4 figures Submitted to Physical Review Letter
The effects of intrathecal midazolam on the duration of analgesia in patients undergoing knee arthroscopy
Background: Spinal anaesthesia is a common anaesthetic technique for lower limb surgery. Many adjuvants have been tried to prolong the duration of analgesia provided by local anaesthetics when administered intrathecally. Midazolam has been shown to prolong the duration of analgesia when used as an adjuvant, providing the added advantages of mild sedation and amnesia, while being devoid of neurotoxicity, and the adverse effects of opioids. This study was designed to evaluate the effect of 2 mg preservative-free intrathecal midazolam added to spinal bupivacaine during postoperative analgesia, and the incidence of adverse effects, if any, in patients undergoing knee arthroscopies. Method: Fifty consenting American Society of Anesthesiologists (ASA) physical status I or II patients of either gender (men = 19, women = 31), aged between 18-56 years, were randomly allocated to two groups (25 each). Group M received 0.5% hyperbaric bupivacaine with preservative-free midazolam 2 mg intrathecally, and Group S received 0.5% hyperbaric bupivacaine with saline intrathecally. Peak sensory level, total duration of analgesia, duration of motor blockade, pain score using the Visual Analogue Scale, and sedation score using the Observer Assessment Score of Sedation were assessed, along with vital parameters, namely heart rate and systolic, diastolic and mean blood pressure. Results: The total duration of analgesia observed was significantly higher in Group M (399 ± 88.11 minutes) vs. Group S (301.60 ± 110.14 minutes), and the pain score was lower in Group M (33.6 ± 4.68 mm) vs. Group S (56.6 ± 8.64 mm). Conclusion: The addition of preservative-free midazolam 2 mg to intrathecal 0.5% hyperbaric bupivacaine prolongs the duration of analgesia without any observed adverse effects in patients undergoing knee arthroscopies.Keywords: intrathecal midazolam, spinal anaesthesi
A Study of Serum C-Reactive Protein (CRP) at Admission as a Predictor of Outcome in Febrile Children
Techniques of deep learning and image processing in plant leaf disease detection: a review
Computer vision techniques are an emerging trend today. Digital image processing is gaining popularity because of the significant upsurge in the usage of digital images over the internet. Digital image processing is a practice that can help in designing sophisticated high-end machines, which can hold the ophthalmic functionality of the human eye. In agriculture, leaf examination is important for disease identification and fair warning for any deficiency within the plant. Many prominent plant species are facing extinction because of a lack of knowledge. A proper realization of computer vision techniques aid in extracting a significant amount of information from leaf image. This necessitates the requirement of an automatic leaf disease detection method to diagnose disease occurrences and severity, for timely crop management, by spraying pesticides. This study focuses on techniques of digital image processing and machine learning rendered in plant leaf disease detection, which has great potential in precision agriculture. To support this study, techniques exercised by various researchers in recent years are tabulated
Genetic and Neuroanatomical Support for Functional Brain Network Dynamics in Epilepsy
Focal epilepsy is a devastating neurological disorder that affects an
overwhelming number of patients worldwide, many of whom prove resistant to
medication. The efficacy of current innovative technologies for the treatment
of these patients has been stalled by the lack of accurate and effective
methods to fuse multimodal neuroimaging data to map anatomical targets driving
seizure dynamics. Here we propose a parsimonious model that explains how
large-scale anatomical networks and shared genetic constraints shape
inter-regional communication in focal epilepsy. In extensive ECoG recordings
acquired from a group of patients with medically refractory focal-onset
epilepsy, we find that ictal and preictal functional brain network dynamics can
be accurately predicted from features of brain anatomy and geometry, patterns
of white matter connectivity, and constraints complicit in patterns of gene
coexpression, all of which are conserved across healthy adult populations.
Moreover, we uncover evidence that markers of non-conserved architecture,
potentially driven by idiosyncratic pathology of single subjects, are most
prevalent in high frequency ictal dynamics and low frequency preictal dynamics.
Finally, we find that ictal dynamics are better predicted by white matter
features and more poorly predicted by geometry and genetic constraints than
preictal dynamics, suggesting that the functional brain network dynamics
manifest in seizures rely on - and may directly propagate along - underlying
white matter structure that is largely conserved across humans. Broadly, our
work offers insights into the generic architectural principles of the human
brain that impact seizure dynamics, and could be extended to further our
understanding, models, and predictions of subject-level pathology and response
to intervention
Test for interlayer coherence in a quasi-two-dimensional superconductor
Peaks in the magnetoresistivity of the layered superconductor
-(BEDT-TTF)Cu(NCS), measured in fields T applied
within the layers, show that the Fermi surface is extended in the interlayer
direction and enable the interlayer transfer integral (
meV) to be deduced. However, the quasiparticle scattering rate is
such that , implying that
-(BEDT-TTF)Cu(NCS) meets the criterion used to identify
interlayer incoherence. The applicability of this criterion to anisotropic
materials is thus shown to be questionable.Comment: 5 pages, 4 figure
Acute Toxicity and Vascular Properties of Seed of Parkia Biglobosa (Jacq) R. Br Gift (Mimosaceae) on Rat Aorta
The authors report here the results of study on Parkia biglobosa seeds used in Burkina Faso for arterial hypertension treatment. Investigations were done on acute toxicity and vascular properties of fermented and roasted seeds. Acute toxicity test using mice, revealed by the intraperitoneal route a lethal dose 50 (LD50) of 1800 mg/kg and 1600 mg/kg of body weight for aqueous extract from roasted and fermented seeds respectively. According to the scale of Hodge and Sterner and that of the World Health Organization, such drugs would be classified lightly toxic. Oral administration (up to 3000 mg/kg) did not induce any death of animal. For the vascular properties, the effects of these products were tested on the aorta isolated from rats. The cumulative administration of extract from roasted and fermented seeds (0.1-10 mg/mL) in an organ bath induced a concentration-dependent relaxation of the aorta pre contracted by phenylephrine, with or without functional endothelium. The extracts (10 mg/mL) inhibited for 100% the contraction induced by phenylephrine. The EC50 values in presence and absence of endothelium were respectively of 5.37 ± 0.12 and 4.19 ± 1.02 mg/mL for fermented seeds; for roasted seeds these values were respectively, 5.39 ± 1.12 and 5.93 ± 0.95 mg/mL. Nevertheless, low concentration of roasted seeds (1-4 mg/mL) induced endothelium-dependent relaxation and this effect was inhibited by indomethacin (10-5M), and not by L-NAME (310-4M). These experimental results revealed a vasorelaxant effect of P. biglobosa seeds. P. biglobosa seems to act directly on the smooth muscle and via endothelium involving the generation of vasodilatating prostaglandins. This vasodilator effect would be in favor of an anti hypertensive property of P. biglobosa seeds.Key words: Acute toxicity; vasodilator; endothelium; Parkia biglobosa
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