196,207 research outputs found
OBSERVATIONAL CONSTRAINTS OF THE INTERACTION BETWEEN PLANETS AND PROTOPLANETARY DISKS
No full textOver the course of almost three decades, exoplanet research has unveiled thousands of planets orbiting stars beyond our Sun. Surprisingly, the majority of these exoplanetary systems exhibit significant differences from our own Solar System. To comprehend the reasons behind these distinctions, it is imperative to study how planets form. Planets take shape during the star formation process, emerging from the material within the protoplanetary disk surrounding the young protostar. Interactions between these newly formed planets and the disk create observable effects on the disk itself, which can be detected in the sub-millimeter to centimeter wavelength range through advanced interferometers like ALMA and VLA.
In this Thesis, I explore various protoplanetary disks, each possessing unique characteristics. They range from extended disks with noticeable substructures in dust emission to a disk surrounding a very low-mass star that may have undergone giant planet formation, as well as a compact, structureless disk exhibiting a peculiar behavior whose origin remains uncertain. The methodologies employed in these investigations are diverse, encompassing high-resolution ALMA observations, comprehensive numerical modeling involving hydrodynamical and radiative transfer simulations, and a multiwavelength analysis spanning from centimeter to sub-millimeter wavelengths, incorporating data from VLA, ALMA, and other interferometers. In all the systems under examination, the presence of planets could potentially play a role, whether giant planets shaping observed dust substructures at tens or hundreds of astronomical units or inner planets generating unresolved substructures, preventing radial drift and leading to the formation of a compact disk
Sphenopalatine endoscopic ganglion block : a revision of a traditional technique for cluster headache
No full textThe diagnosis of chronic cluster headache (CH), the most painful form of headache, is based on typical clinical features characterized by strictly unilateral pain with no side shift and ipsilateral oculofacial autonomic phenomena. The attacks occur several times a day for periods of 1 to 2 months in the episodic form of the disease or less frequently on a daily basis in the chronic form. The pathogenesis of CH involves the activation of parasympathetic nerve structures located within the sphenopalatine ganglion (SPG), which explains many of the associated symptoms, whereas the activation of the ipsilateral hypothalamic gray matter may explain its typical circadian and circannual periodicity. A number of surgical approaches have been tried in cases of chronic CH resistant to pharmacologic therapy, of which SPG blockade has been shown to have certain efficacy. We have adopted a new technique based on endoscopic ganglion blockade that approaches the pterigo-palatine fossa by way of the lateral nasal wall and consists of the injection of a mixture of local anesthetics and corticosteroids, which was performed in 20 selected patients with chronic CH, according to the International Headache Society criteria (18 male, 2 female; mean age 40 yr), who were selected for SPG blockade because they were totally drug resistant. The symptoms improved significantly, but always only temporarily, in 11 cases. These results should be considered rather good because, unlike other frequently used techniques, SPG blockade is not invasive and should therefore always be attempted before submitting patients to more invasive surgical approaches
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
Deep brain stimulation and cluster headache
No full textIn recent years, neuroimaging data have greatly improved the knowledge on trigeminal autonomic cephalalgias' (TACs) central mechanisms. Positron emission tomography studies have shown that the posterior inferior hypothalamic grey matter is activated during cluster headache attacks as well as in short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT). Voxel-based morphometric MRI has also documented alteration in the same area in cluster headache patients. These data suggest that the cluster headache generator is located in this region and leads us to hypothesise that stimulation of this brain area could relieve intractable cluster headache just as deep brain stimulation improves intractable movements disorders. This view received support by the observation that high frequency stimulation of the ipsilateral hypothalamus prevented attacks in an otherwise intractable chronic cluster headache patient previously treated unsuccessfully by surgical procedures to the trigeminal nerve. So far, 16 patients with intractable cronic cluster headache (CCH) and one intractable SUNCT patient have been successfully treated by hypothalamic stimulation. The procedures were well tolerated with no significant adverse events. Hypothalamic DBS is an efficacious and safe procedure to relieve otherwise intractable CCH and SUNCT. (copyright) Springer-Verlag Italia 2005
Chiari malformation-related headache: outcome after surgical treatment
No full textThe outcome of headache in a series of 135 operated CM1 is presented. Favorable results were obtained in 85% of atypical and 93% typical headache with the support of a multidisciplinary approach that restricted the indications for surgery
Difficulties in work-related activities among migraineurs are scarcely collected: results from a literature review.
No full textMigraine affects work productivity in terms of missed workdays and days with reduced productivity. In this literature review, we looked for papers addressing specific difficulties in work-related activities. Twenty-three papers were included in the review, reporting data on 51,135 patients. Results showed that there is some evidence for limitations in skills such as problem solving, and activities such as speaking and driving. However, the way in which problems with remunerative employment are addressed is limited to concepts such as reduced performance or inability to work as usual. Given the paucity of data, a return to patient-derived data will be needed to develop an assessment instrument that is able to collect information on headache-related problems in work activities
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Difficulties in work-related activities among migraineurs are scarcely collected: results from a literature review.
No full textMigraine affects work productivity in terms of missed workdays and days with reduced productivity. In this literature review, we looked for papers addressing specific difficulties in work-related activities. Twenty-three papers were included in the review, reporting data on 51,135 patients. Results showed that there is some evidence for limitations in skills such as problem solving, and activities such as speaking and driving. However, the way in which problems with remunerative employment are addressed is limited to concepts such as reduced performance or inability to work as usual. Given the paucity of data, a return to patient-derived data will be needed to develop an assessment instrument that is able to collect information on headache-related problems in work activities
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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