113 research outputs found

    An Iterative Reconstruction Algorithm for Faraday Tomography

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    Faraday tomography offers crucial information on the magnetized astronomical objects, such as quasars, galaxies, or galaxy clusters, by observing its magnetoionic media. The observed linear polarization spectrum is inverse Fourier transformed to obtain the Faraday dispersion function (FDF), providing us a tomographic distribution of the magnetoionic media along the line of sight. However, this transform gives a poor reconstruction of the FDF because of the instrument's limited wavelength coverage. The current Faraday tomography techniques' inability to reliably solve the above inverse problem has noticeably plagued cosmic magnetism studies. We propose a new algorithm inspired by the well-studied area of signal restoration, called the Constraining and Restoring iterative Algorithm for Faraday Tomography (CRAFT). This iterative model-independent algorithm is computationally inexpensive and only requires weak physically-motivated assumptions to produce high fidelity FDF reconstructions. We demonstrate an application for a realistic synthetic model FDF of the Milky Way, where CRAFT shows greater potential over other popular model-independent techniques. The dependence of observational frequency coverage on the various techniques' reconstruction performance is also demonstrated for a simpler FDF. CRAFT exhibits improvements even over model-dependent techniques (i.e., QU-fitting) by capturing complex multi-scale features of the FDF amplitude and polarization angle variations within a source. The proposed approach will be of utmost importance for future cosmic magnetism studies, especially with broadband polarization data from the Square Kilometre Array and its precursors. We make the CRAFT code publicly available.Comment: Accepted for publication in MNRAS. 13 pages and 12 figure

    Low-Lying Excited States of Quantum Antiferromagnets on a Triangular Lattice

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    We study low-lying states of the XY and Heisenberg antiferromagnets on a triangular lattice to clarify whether spontaneous symmetry breaking occurs at T=0T=0 in the thermodynamic limit. Approximate forms of low-lying states are proposed, in which degrees of freedom of the sublattice magnetization and of the chirality are separated. It is shown that low-lying states can be accurately described with the present approximation. It was argued that low-lying states play an important role in symmetry breaking. With help of this approximation, we discuss the contribution of low-lying states to symmetry breaking of two types, namely creation of the spontaneous sublattice magnetization and the spontaneous chirality. Furthermore, to show an evidence for the occurrence of the symmetry breaking, we numerically study the low-lying states of finite systems of the XY and Heisenberg antiferromagnets. It is found that the necessary conditions for the symmetry breaking to occur are satisfied in these models.Comment: LaTex 22 pages, figures included in uuencoded form, to be published in J.Stat.Phy

    Extracorporeal Shock Wave Lithotripsy (ESWL) without Endoscopic Lithotomy for Pancreatolithiasis : A Report of Two Cases

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    Extracorporeal shock wave lithotripsy (ESWL) without endoscopic sphincterotomy (EST) for pancreatic duct stones was performed in two patients with chronic pancreatitis. Case 1 was a 37-year-old man. Pancreatic stones were observed in the pancreatic head and tail region with a persistent pancreatic fistula. ESWL without EST for pancreatolithiasis was performed two times. Almost all the stones in the pancreatic head were disintegrated without any complications by ESWL (4700 shock waves at 24.0 KV) under fluoroscopic control using a lithotriptor (Dornier MLF 5000). Consequently, the fistula closed and the pancreatic exocrine function recovered. Case 2 was a 65-year-old woman suffering from chronic relapsing pancreatitis with calcified stones in the pancreatic head region. ESWL (5700 shock waves at 23.0 KV) without EST produced complete disintegration of the stones without any complications. Seven days later, almost all of the stones in the pancreatic head were diminished. Thereafter, we observed not only amelioration of the symptoms of pancreatitis but also improvement in pancreatic exocrine function. Thus, ESWL treatment without EST was a safe and effective method for pancreatolithiasis and should be considered a high-priority non-surgical treatment for pancreatolithiasis

    Possible chiral phase transition in two-dimensional solid 3^3He

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    We study a spin system with two- and four-spin exchange interactions on the triangular lattice, which is a possible model for the nuclear magnetism of solid 3^3He layers. It is found that a novel spin structure with scalar chiral order appears if the four-spin interaction is dominant. Ground-state properties are studied using the spin-wave approximation. A phase transition concerning the scalar chirality occurs at a finite temperature, even though the dimensionality of the system is two and the interaction has isotropic spin symmetry. Critical properties of this transition are studied with Monte Carlo simulations in the classical limit.Comment: 4 pages, Revtex, 4 figures, to appear in Phys.Rev.Let

    Spontaneous Rupture of Hepatocellular Carcinoma

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    Of 105 patients of hepatocellular carcinoma (HCC) treated during 1970-1988, twelve patients had spontaneous rupture of carcinomatous nodules. 1) Of previous 6 cases, five were treated by conventional surgical procedures such as packing and suture, and all died. One case underwent right lobectomy following guaze pack and lived for 15 months. 2) The recent 6 cases underwent emergency transcatheter arterial embolization (TAE ) and two died of hepatic failure due to severe cirrhosis. The other 4 cases had successful control , of bleeding which allowed further treatment of HCC ; hepatectomy in 3 and repeated TAE in one. 3) All cases had precirrhosis or cirrhosis. Pathologically, ruptured tumors expansively growing with capsule invasion of cancer cells, and portal tumor thrombus were recognized in resected or autopsy specimens. DNA aneuploid HCC on flow cytometric DNA analysis were found in 4 out of 5 cases. In conclusion, hepatic resection following embolization, when possible, would seem to be rational treatment for spontaneous rupture of HCC, although the prognosis is still extremely poor despite successful control of bleeding

    An integrated analysis platform merging SuperDARN data within the THEMIS tool developed by ERG-Science Center (ERG-SC)

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    The Energization and Radiation in Geospace (ERG) mission seeks to explore the dynamics of the radiation belts in the Earthā€™s inner magnetosphere with a space-borne probe (ERG satellite) in coordination with related ground observations and simulations/ modeling studies. For this mission, the Science Center of the ERG project (ERG-SC) will provide a useful data analysis platform based on the THEMIS Data Analysis software Suite (TDAS), which has been widely used by researchers in many conjunction studies of the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft and ground data. To import SuperDARN data to this highly useful platform, ERG-SC, in close collaboration with SuperDARN groups, developed the Common Data Format (CDF) design suitable for fitacf data and has prepared an open database of SuperDARN data archived in CDF. ERG-SC has also been developing programs written in Interactive Data Language (IDL) to load fitacf CDF files and to generate various kinds of plotsāˆ’not only range-time-intensity-type plots but also two-dimensional map plots that can be superposed with other data, such as all-sky images of THEMIS-GBO and orbital footprints of various satellites. The CDF-TDAS scheme developed by ERG-SC will make it easier for researchers who are not familiar with SuperDARN data to access and analyze SuperDARN data and thereby facilitate collaborative studies with satellite data, such as the inner magnetosphere data provided by the ERG (Japan)āˆ’RBSP (USA)āˆ’THEMIS (USA) fleet

    Management of Blunt Hepatic Trauma

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    One hundred and twelve consecutive cases with blunt hepatic trauma between January 1, 1965 and December 31, 1988 at the First Dpartment of Surgery, Nagasaki University were reviewed. Fifty-seven patients had minor injuries, 33 moderate injuries and 22 severe injuries. Sixty-five patients (58%) sustained also one of more associated injuries. Out of 43 patients over the last ten years 30 were diagnosed by US or CT. Eighty-eight patients (78.3%) underwent laparotomy ; laparotomy and drainage alone in 13, suture and packs in 57, debridement and minor liver resection in 11 and right lobectomy in 9. The results of treated patients were assessed according to the grading of liver injury and assocated injury. The overall mortality was 13.4% (15 of 112). True liver-related mortality due to hemorrhage was 26.7% (4 of 5), and the other 11 patients who died were due to refractory shock and the development of multiple organ failure (MOF). Twenty-one patients were conservatively managed with only one death, and the other 20 survivors had no complications and healed completely from 6 to 12 months after trauma. Although lobectomy or resectional debridement are advocated as an operative procedure for massive injury, a conservative management for mild or moderate ruptures is still recommended as far as possible

    Paraneoplastic Antigen-Like 5 Gene (PNMA5) Is Preferentially Expressed in the Association Areas in a Primate Specific Manner

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    To understand the relationship between the structure and function of primate neocortical areas at a molecular level, we have been screening for genes differentially expressed across macaque neocortical areas by restriction landmark cDNA scanning (RLCS). Here, we report enriched expression of the paraneoplastic antigen-like 5 gene (PNMA5) in association areas but not in primary sensory areas, with the lowest expression level in primary visual cortex. In situ hybridization in the primary sensory areas revealed PNMA5 mRNA expression restricted to layer II. Along the ventral visual pathway, the expression gradually increased in the excitatory neurons from the primary to higher visual areas. This differential expression pattern was very similar to that of retinol-binding protein (RBP) mRNA, another association-area-enriched gene that we reported previously. Additional expression analysis for comparison of other genes in the PNMA gene family, PNMA1, PNMA2, PNMA3, and MOAP1 (PNMA4), showed that they were widely expressed across areas and layers but without the differentiated pattern of PNMA5. In mouse brains, PNMA1 was only faintly expressed and PNMA5 was not detected. Sequence analysis showed divergence of PNMA5 sequences among mammals. These findings suggest that PNMA5 acquired a certain specialized role in the association areas of the neocortex during primate evolution

    CNVs in Three Psychiatric Disorders

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    BACKGROUND: We aimed to determine the similarities and differences in the roles of genic and regulatory copy number variations (CNVs) in bipolar disorder (BD), schizophrenia (SCZ), and autism spectrum disorder (ASD). METHODS: Based on high-resolution CNV data from 8708 Japanese samples, we performed to our knowledge the largest cross-disorder analysis of genic and regulatory CNVs in BD, SCZ, and ASD. RESULTS: In genic CNVs, we found an increased burden of smaller (500 kb) exonic CNVs in SCZ/ASD. Pathogenic CNVs linked to neurodevelopmental disorders were significantly associated with the risk for each disorder, but BD and SCZ/ASD differed in terms of the effect size (smaller in BD) and subtype distribution of CNVs linked to neurodevelopmental disorders. We identified 3 synaptic genes (DLG2, PCDH15, and ASTN2) as risk factors for BD. Whereas gene set analysis showed that BD-associated pathways were restricted to chromatin biology, SCZ and ASD involved more extensive and similar pathways. Nevertheless, a correlation analysis of gene set results indicated weak but significant pathway similarities between BD and SCZ or ASD (r = 0.25ā€“0.31). In SCZ and ASD, but not BD, CNVs were significantly enriched in enhancers and promoters in brain tissue. CONCLUSIONS: BD and SCZ/ASD differ in terms of CNV burden, characteristics of CNVs linked to neurodevelopmental disorders, and regulatory CNVs. On the other hand, they have shared molecular mechanisms, including chromatin biology. The BD risk genes identified here could provide insight into the pathogenesis of BD
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