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Search Results: 1 - 10 of 54710 matches for " Jonathan Di John. "
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Conceptualización de las causas y consecuencias de los Estados fallidos: una rese?a crítica de la literatura
Di John,Jonathan;
Revista de Estudios Sociales , 2010,
Abstract: this article provides a critical review of recent literature which has attempted to define what a 'failed state' is and explain why such states emerge. it is argued that aggregate indices of 'failure' are misleading due to the wide variations of capacity across state functions within a polity. the focus on ranking states also distracts attention away from analyses concerning the dynamics of state capacity. moreover, many of the definitions either compare reality to a weberian ideal, or assume that violence is 'development in reverse', both of which are ahistorical and unhelpful as a guide to policy. the second part of the paper assesses the contributions of functionalist, 'new war', and neo-tillean approaches to explaining state failure. the paper finds that while these theories take concrete historical situations seriously, they have important theoretical and empirical shortcomings. finally, the conclusion outlines an agenda for further research.
Conceptualización de las causas y consecuencias de los Estados fallidos: una rese a crítica de la literatura.
Jonathan Di John.
Revista de Estudios Sociales , 2010,
Abstract: This article provides a critical review of recent literature which has attempted to define what a ‘failed state’ is and explain why such states emerge. It is argued that aggregate indices of ‘failure’ are misleading due to the wide variations of capacity across state functions within a polity. The focus on ranking states also distracts attention away from analyses concerning the dynamics of state capacity. Moreover, many of the definitions either compare reality to a Weberian ideal, or assume that violence is ‘development in reverse’, both of which are ahistorical and unhelpful as a guide to policy. The second part of the paper assesses the contributions of functionalist, ‘new war’, and neo-Tillean approaches to explaining state failure. The paper finds that while these theories take concrete historical situations seriously, they have important theoretical and empirical shortcomings. Finally, the conclusion outlines an agenda for further research.
A Seated Single-Person Dial-Test for Posterolateral Corner and Posterior Cruciate Ligament Knee Injuries  [PDF]
Jibu John Joseph, Jonathan Dearing
Open Journal of Clinical Diagnostics (OJCD) , 2014, DOI: 10.4236/ojcd.2014.41004
Abstract: Background: Injuries to the posterolateral corner of the knee (PLC) can be difficult to diagnose and are often missed. The prone dial test can be difficult to perform in the acute setting and the supine dial test requires an assistant. Purpose: We present a simple single person seated dial test that can easily be performed in all patients with a suspected diagnosis of PLC injury. Study Design: Case Series. Method: The patient is seated on the edge of the examination couch with their knees flexed over the side and their calves pressed against the couch to reduce any posterior tibial subluxation. The patients’ knees are placed together ensuring the pelvis is square; the knees are at the same level, and the patellae are facing anteriorly. The patients place their hands against the side of their knees and hold their knees together in this position. The examiner then grasps the patient’s feet, approximates the medial malleoli and exerts a lateral rotational force at 30 and 90 degrees of knee flexion. Results: This test has 100% accuracy for diagnosing PLC injury in our institution. Conclusion: We present a sample to use alternative to traditional dial testing that does not require an assistant and also does not require the patient to be prone, thus limiting discomfort in the acute setting.


ALMA observations of a misaligned binary protoplanetary disk system in Orion
Jonathan P. Williams,Rita K. Mann,James Di Francesco,Sean M. Andrews,A. Meredith Hughes,Luca Ricci,John Bally,Doug Johnstone,Brenda Matthews
Physics , 2014, DOI: 10.1088/0004-637X/796/2/120
Abstract: We present ALMA observations of a wide binary system in Orion, with projected separation 440 AU, in which we detect submillimeter emission from the protoplanetary disks around each star. Both disks appear moderately massive and have strong line emission in CO 3-2, HCO+ 4-3, and HCN 3-2. In addition, CS 7-6 is detected in one disk. The line-to-continuum ratios are similar for the two disks in each of the lines. From the resolved velocity gradients across each disk, we constrain the masses of the central stars, and show consistency with optical-infrared spectroscopy, both indicative of a high mass ratio ~9. The small difference between the systemic velocities indicates that the binary orbital plane is close to face-on. The angle between the projected disk rotation axes is very high, ~72 degrees, showing that the system did not form from a single massive disk or a rigidly rotating cloud core. This finding, which adds to related evidence from disk geometries in other systems, protostellar outflows, stellar rotation, and similar recent ALMA results, demonstrates that turbulence or dynamical interactions act on small scales well below that of molecular cores during the early stages of star formation.
Protoplanetary Disk Masses in the Young NGC 2024 Cluster
Rita K. Mann,Sean M. Andrews,Josh A. Eisner,Jonathan P. Williams,Michael R. Meyer,James Di Francesco,John M. Carpenter,Doug Johnstone
Physics , 2015, DOI: 10.1088/0004-637X/802/2/77
Abstract: We present the results from a Submillimeter Array survey of the 887 micron continuum emission from the protoplanetary disks around 95 young stars in the young cluster NGC 2024. Emission was detected from 22 infrared sources, with flux densities from ~5 to 330 mJy; upper limits (at 3sigma) for the other 73 sources range from 3 to 24 mJy. For standard assumptions, the corresponding disk masses range from ~0.003 to 0.2Msolar, with upper limits at 0.002--0.01Msolar. The NGC 2024 sample has a slightly more populated tail at the high end of its disk mass distribution compared to other clusters, but without more information on the nature of the sample hosts it remains unclear if this difference is statistically significant or a superficial selection effect. Unlike in the Orion Trapezium, there is no evidence for a disk mass dependence on the (projected) separation from the massive star IRS2b in the NGC 2024 cluster. We suggest that this is due to either the cluster youth or a comparatively weaker photoionizing radiation field.
ALMA Observations of the Largest Proto-Planetary Disk in the Orion Nebula, 114-426: A CO Silhouette
John Bally,Rita K. Mann,Josh Eisner,Sean M. Andrews,James Di Francesco,Meredith Hughes,Doug Johnstone,Brenda Matthews,Luca Ricci,Jonathan P. Williams
Physics , 2015, DOI: 10.1088/0004-637X/808/1/69
Abstract: We present ALMA observations of the largest protoplanetary disk in the Orion Nebula, 114-426. Detectable 345 GHz (856 micron) dust continuum is produced only in the 350 AU central region of the ~1000 AU diameter silhouette seen against the bright H-alpha background in HST images. Assuming optically thin dust emission at 345 GHz, a gas-to-dust ratio of 100, and a grain temperature of 20 K, the disk gas-mass is estimated to be 3.1 +/- 0.6 Jupiter masses. If most solids and ices have have been incorporated into large grains, however, this value is a lower limit. The disk is not detected in dense-gas tracers such as HCO+ J=4-3, HCN J=4-3, or CS =7-6. These results may indicate that the 114-426 disk is evolved and depleted in some light organic compounds found in molecular clouds. The CO J=3-2 line is seen in absorption against the bright 50 to 80 K background of the Orion A molecular cloud over the full spatial extent and a little beyond the dust continuum emission. The CO absorption reaches a depth of 27 K below the background CO emission at VLSR ~6.7 km/s about 0.52 arcseconds (210 AU) northeast and 12 K below the background CO emission at VLSR ~ 9.7 km/s about 0.34 arcseconds (140 AU) southwest of the suspected location of the central star, implying that the embedded star has a mass less than 1 Solar mass .
ALMA Observations of the Orion Proplyds
Rita K. Mann,James Di Francesco,Doug Johnstone,Sean M. Andrews,Jonathan P. Williams,John Bally,Luca Ricci,A. Meredith Hughes,Brenda C. Matthews
Physics , 2014, DOI: 10.1088/0004-637X/784/1/82
Abstract: We present ALMA observations of protoplanetary disks ("proplyds") in the Orion Nebula Cluster. We imaged 5 individual fields at 856um containing 22 HST-identified proplyds and detected 21 of them. Eight of those disks were detected for the first time at submillimeter wavelengths, including the most prominent, well-known proplyd in the entire Orion Nebula, 114-426. Thermal dust emission in excess of any free-free component was measured in all but one of the detected disks, and ranged between 1-163 mJy, with resulting disk masses of 0.3-79 Mjup. An additional 26 stars with no prior evidence of associated disks in HST observations were also imaged within the 5 fields, but only 2 were detected. The disk mass upper limits for the undetected targets, which include OB stars, theta1Ori C and theta1Ori F, range from 0.1-0.6 Mjup. Combining these ALMA data with previous SMA observations, we find a lack of massive (>3 Mjup) disks in the extreme-UV dominated region of Orion, within 0.03 pc of O-star theta1Ori C. At larger separations from theta1Ori C, in the far-UV dominated region, there is a wide range of disk masses, similar to what is found in low-mass star forming regions. Taken together, these results suggest that a rapid dissipation of disk masses likely inhibits potential planet formation in the extreme-UV dominated regions of OB associations, but leaves disks in the far-UV dominated regions relatively unaffected.
Information locking in black holes
John Smolin,Jonathan Oppenheim
Physics , 2005, DOI: 10.1103/PhysRevLett.96.081302
Abstract: The black hole information loss paradox has plagued physicists since Hawking's discovery that black holes evaporate thermally in contradiction to the unitarity expected by quantum mechanics. Here we show that one of the central presumptions of the debate is incorrect. Ensuring that information not escape during the semi-classical evaporation process does not require that all the information remain in the black hole until the final stages of evaporation. Using recent results in quantum information theory, we find that the amount of information that must remain in the black hole until the final stages of evaporation can be very small, even though the amount already radiated away is negligible. Quantum effects mean that information need not be additive: a small number of quanta can lock a large amount of information, making it inaccessible. When this small number of locking quanta are finally emitted, the full information (and unitarity) is restored. Only if the number of initial states is restricted will the locking mechanism leak out information early.
Preferential attachment with choice
John Haslegrave,Jonathan Jordan
Mathematics , 2014,
Abstract: We consider the degree distributions of preferential attachment random graph models with choice similar to those considered in recent work by Malyshkin and Paquette and Krapivsky and Redner. In these models a new vertex chooses $r$ vertices according to a preferential rule and connects to the vertex in the selection with the $s$th highest degree. For meek choice, where $s>1$, we show that both double exponential decay of the degree distribution and condensation-like behaviour are possible, and provide a criterion to distinguish between them. For greedy choice, where $s=1$, we confirm that the degree distribution asympotically follows a power law with logarithmic correction when $r=2$ and shows condensation-like behaviour when $r>2$.
Post-Natal Spontaneous Resolution of a Congenital Pulmonary Airway Malformation in an Infant: Plain Radiographic and CT Manifestations  [PDF]
John Amodio, Agnes Perenyi, Jonathan Zember, Matthew Smith
Open Journal of Medical Imaging (OJMI) , 2012, DOI: 10.4236/ojmi.2012.22008
Abstract: We present a case of a near-term infant who developed respiratory distress, shortly after birth. Chest X-ray showed a right sided tension pneumothorax (PTX) with a large air containing structure at the base of the right hemithorax. The pneumothorax was partially evacuated with needle aspiration at which time the patient became asymptomatic, despite a small residual pneumothorax. CT scan of the chest confirmed a multilocular air-filled structure within the right lower lobe, most likely consistent with a congenital pulmonary airway malformation (CPAM). Subsequently, there was spontaneous resolution of the PTX and CPAM prior to surgical intervention. This case illustrates post-natal spontaneous resolution of a CPAM, thus obviating the need for surgical removal.
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