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Sample records for acute zonal occult

  1. Photoreceptor atrophy in acute zonal occult outer retinopathy

    DEFF Research Database (Denmark)

    Zibrandtsen, N.; Munch, I.C.; Klemp, K.

    2008-01-01

    PURPOSE: To assess retinal morphology in acute zonal occult outer retinopathy (AZOOR) without ophthalmoscopically visible fundus changes. METHODS: Retrospective case series. Two consecutive patients with bilateral AZOOR with photopsia corresponding to areas of visual field loss and a normal fundus...

  2. Photoreceptor atrophy in acute zonal occult outer retinopathy

    DEFF Research Database (Denmark)

    Zibrandtsen, N.; Munch, I.C.; Klemp, K.

    2008-01-01

    To assess retinal morphology in acute zonal occult outer retinopathy (AZOOR) without ophthalmoscopically visible fundus changes. Retrospective case series. Two consecutive patients with bilateral AZOOR with photopsia corresponding to areas of visual field loss and a normal fundus appearance were...

  3. Photoreceptor atrophy in acute zonal occult outer retinopathy

    DEFF Research Database (Denmark)

    Zibrandtsen, N.; Munch, I.C.; Klemp, K.

    2006-01-01

    Purpose: To assess retinal morphology in acute zonal occult outer retinopathy (AZOOR). Methods: Three patients with a normal ophthalmoscopic fundus appearance, a history of photopsia, and visual field loss compatible with AZOOR were examined using optical coherence tomography, automated perimetry...

  4. Acute Zonal Occult Outer Retinopathy with Atypical Findings

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    Dimitrios Karagiannis

    2014-01-01

    Full Text Available Background. To report a case of acute zonal occult outer retinopathy (AZOOR with atypical electrophysiology findings. Case Presentation. A 23-year-old-female presented with visual acuity deterioration in her right eye accompanied by photopsia bilaterally. Corrected distance visual acuity at presentation was 20/50 in the right eye and 20/20 in the left eye. Fundus examination was unremarkable. Visual field (VF testing revealed a large scotoma. Pattern and full-field electroretinograms (PERG and ERG revealed macular involvement associated with generalized retinal dysfunction. Electrooculogram (EOG light rise and the Arden ratio were within normal limits bilaterally. The patient was diagnosed with AZOOR due to clinical findings, visual field defect, and ERG findings. Conclusion. This is a case of AZOOR with characteristic VF defects and clinical symptoms presenting with atypical EOG findings.

  5. OCT Angiography Identification of Choroidal Neovascularization Secondary to Acute Zonal Occult Outer Retinopathy.

    Science.gov (United States)

    Levison, Ashleigh L; Baynes, Kimberly; Lowder, Careen Y; Srivastava, Sunil K

    2016-01-01

    A 74-year-old female with acute zonal occult outer retinopathy presented with a new lesion suspicious for choroidal neovascularization (CNV) in her right eye. Optical coherence tomography angiography (OCTA) confirmed the presence of CNV. OCTA is a new imaging technique that may help guide diagnosis and management of choroidal neovascular membranes in uveitic diseases.

  6. Acute Zonal Occult Outer Retinopathy (AZOOR in a patient with Hashimoto's thyroiditis

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    Luiz Reis Barbosa Júnior

    Full Text Available ABSTRACT Acute zonal occult outer retinopathy (AZOOR is a rare disease characterized by an acute damage of one or more external retinal zones leading to the visual field or the visual acuity impairment associated with small or no changes in the fundus examination.The main clinical symptoms are scotomas and the sudden onset of photopsias. Abnormal findings on electroretinography and visual field defects are critical for the diagnosis. Central vision is usually preserved and the stabilization occurs in six months in most cases. The objective of this article is to describe a 24-month follow-up of a patient with AZOOR and correlate the findings with the typical features of this disease.

  7. Acute Zonal Occult Outer Retinopathy: Vision Loss in an Active Duty Soldier

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    Courtney M. Crawford

    2013-01-01

    Full Text Available Objective. To describe a case of acute zonal occult outer retinopathy (AZOOR in an active duty patient. Methods. In this paper we studied fundus photographs, optical coherence tomograph, Humphrey visual field 30-2, fundus autofluorescence images, fluorescein angiograms, and electroretinography. Results. Exam findings on presentation: a 34-year-old American Indian female presented with bilateral photopsias, early RPE irregularity, and an early temporal visual field defect. Progression RPE damage and visual field defect along with ERG findings support final diagnosis of AZOOR. Conclusion. AZOOR may initially be identified as a broader category of disease called the “AZOOR complex of disorders”. Specific visual field defects, ERG results, and clinical exam findings will help distinguish AZOOR from other similar disorders.

  8. Acute Zonal Cone Photoreceptor Outer Segment Loss.

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    Aleman, Tomas S; Sandhu, Harpal S; Serrano, Leona W; Traband, Anastasia; Lau, Marisa K; Adamus, Grazyna; Avery, Robert A

    2017-05-01

    The diagnostic path presented narrows down the cause of acute vision loss to the cone photoreceptor outer segment and will refocus the search for the cause of similar currently idiopathic conditions. To describe the structural and functional associations found in a patient with acute zonal occult photoreceptor loss. A case report of an adolescent boy with acute visual field loss despite a normal fundus examination performed at a university teaching hospital. Results of a complete ophthalmic examination, full-field flash electroretinography (ERG) and multifocal ERG, light-adapted achromatic and 2-color dark-adapted perimetry, and microperimetry. Imaging was performed with spectral-domain optical coherence tomography (SD-OCT), near-infrared (NIR) and short-wavelength (SW) fundus autofluorescence (FAF), and NIR reflectance (REF). The patient was evaluated within a week of the onset of a scotoma in the nasal field of his left eye. Visual acuity was 20/20 OU, and color vision was normal in both eyes. Results of the fundus examination and of SW-FAF and NIR-FAF imaging were normal in both eyes, whereas NIR-REF imaging showed a region of hyporeflectance temporal to the fovea that corresponded with a dense relative scotoma noted on light-adapted static perimetry in the left eye. Loss in the photoreceptor outer segment detected by SD-OCT co-localized with an area of dense cone dysfunction detected on light-adapted perimetry and multifocal ERG but with near-normal rod-mediated vision according to results of 2-color dark-adapted perimetry. Full-field flash ERG findings were normal in both eyes. The outer nuclear layer and inner retinal thicknesses were normal. Localized, isolated cone dysfunction may represent the earliest photoreceptor abnormality or a distinct entity within the acute zonal occult outer retinopathy complex. Acute zonal occult outer retinopathy should be considered in patients with acute vision loss and abnormalities on NIR-REF imaging, especially if

  9. A New Look at Titan's Zonal Winds from Cassini Radio Occultations

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    Flasar, F. M.; Schinder, P. J.

    2012-01-01

    We use the existing thirteen Cassini radio'occultation soundings to construct a meridional cross section of geopotential height vs. pressure and latitude. The assumption of balanced flow permits the construction of a similar cross section of zonal winds, from near the surface to the 0.1'mbar level. In the lower troposphere, the winds are approx.10 m/s, except within 20deg of the equator, where they are much smaller. The winds increase higher up in the troposphere to nearly 40 m/s in the tropopause region, but then decay rapidly in the lower stratosphere to near'zero values at 20 mbar (approx.80 km), reminiscent of the Huygens Doppler Wind Experiment result. This null zone extends over most latitudes, except for limited bands at mid'latitudes. Higher up in the stratosphere, the winds become larger. They are highest in the northern (winter) hemisphere. We compare the occultation results with the DWE and CIRS retrievals and discuss the similarities and differences among the data sets.

  10. Occult Pneumothoraces in Acute Trauma Patients

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    Chad Berryman

    2012-12-01

    Full Text Available Introduction: Many traumatic pneumothoraces (PTX are not seen on initial chest radiograph (CR(occult PTX but are detected only on computed tomography (CT. Although CR remains the first toolfor detecting PTX, most trauma patients with significant thoracoabdominal injuries will receive both CTand CR. The primary objective of this study was to retrospectively determine the effectiveness of CR fordetecting PTX in trauma patients. Our hypotheses were that CR is a sensitive indicator of PTX on CT,that chest pain and shortness of breath are good predictors of PTX on CR, and that we could determineother predictors of PTX on CR.Methods: All trauma patients presenting to our Level I trauma center with a CT-diagnosed PTX over a2-year period who had both a CR and a chest CT were included. The CT reading was considered thegold standard for PTX diagnosis. Electronic medical records were searched using key words fordiagnoses, symptoms, demographics, and radiologic results. We recorded the official radiologistreadings for both CR and CT (positive or negative and the size of the PTX on CT (large, moderate,small, or tiny. The outcome variable was dichotomized based on presence or absence of PTXdetected on CR. Descriptive statistics and v2 tests were used for univariate analysis. A regressionanalysis was performed to determine characteristics predictive of a PTX on CR, and 1 variable wasadded to the model for every 10 positive CRs. With equal-size groups, this study has the power of 80%to detect a 10% absolute difference in single predictors of PTX on CR with 45 subjects in each group.Results: There were 134 CT-documented PTXs included in the study. Mean age was 42, and 74%were men. For 66 (49% patients, PTX was detected on CR (sensitivity¼50%. The CR detected 30%of small PTX, 35% of moderate PTX, and 33% of large PTX. Comparing patients with and without PTXon CR, there were no significant differences in shortness of breath or chest pain. There no

  11. High sensitivity of flow cytometry improves detection of occult leptomeningeal disease in acute lymphoblastic leukemia and lymphoblastic lymphoma.

    Science.gov (United States)

    Del Principe, Maria Ilaria; Buccisano, Francesco; Cefalo, Mariagiovanna; Maurillo, Luca; Di Caprio, Luigi; Di Piazza, Fabio; Sarlo, Chiara; De Angelis, Gottardo; Irno Consalvo, Maria; Fraboni, Daniela; De Santis, Giovanna; Ditto, Concetta; Postorino, Massimiliano; Sconocchia, Giuseppe; Del Poeta, Giovanni; Amadori, Sergio; Venditti, Adriano

    2014-09-01

    Conventional cytology (CC) of cerebrospinal fluid (CSF) fails to demonstrate malignant cells in up to 45 % of patients with acute lymphoblastic leukemia or lymphoblastic lymphoma (ALL/LL) in whom occult leptomeningeal disease is present. Flow cytometry (FCM) is considered more sensitive than CC, but clinical implications of CC negativity/CC positivity are not yet established. CSF samples from 38 adult patients with newly diagnosed ALL/LL were examined. Five (13 %) and nine (24 %) specimens were CC positive-FC positive (FCM(pos)/CC(pos)) and CC negative-FC positive (CC(neg)/FCM(pos)), respectively. The remaining 24 (63 %) samples were double negative (CC(neg)/FCM(neg)) (p = 0.001). CC(neg)/FCM(pos) patients showed a significantly shorter overall survival (OS) compared to CC(neg)/FCM(neg) ones. In multivariate analysis, the status of single FCM positivity was demonstrated to affect independently duration of OS (p = 0.005). In conclusion, FCM significantly improves detection of leptomeningeal occult localization in ALL/LL and appears to anticipate an adverse outcome. Further prospective studies on larger series are needed to confirm this preliminary observation.

  12. Zonal structure in plagioclases

    NARCIS (Netherlands)

    Harloff, Ch.

    1926-01-01

    The purpose of this paper is to record the results of a series of observations on zonal plagioelases made with the aid of the Fedorowstage. Some of these results may add to our present knowledge of zonality in general. It is necessary, first of all, to give a definition of what we mean by zonal stru

  13. Occult renal cell carcinoma with acrometastasis and ipsilateral juxta-articular knee lesions mimicking acute inflammation

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    Bhaskar Borgohain

    2012-01-01

    Full Text Available Generally, skeletal peripheral metastases below the elbow and the knee are rare. Skeletal metastases to the hand or foot are very rare; but when they do it may be a revealing clinical finding. Purely lytic lesions are commonly seen in metastases from lung, renal, and thyroid tumors, but they are also known to occur in primary myeloma, brown tumor and lymphomas. A 70-year-old man was brought to the emergency department with acute painful swelling involving his right hand and the right knee. Due to significant accompanying soft tissue swellings cellulitis, acute osteomyelitis and gouty arthropathy were included in the initial differential diagnosis. Radiographs showed pure lytic bony lesion with complete disappearance of lower two third of the second metacarpal, trapezium and trapezoid bones of the right hand along with a lytic subarticular lesion of medial condyle of ipsilateral femur. Chest X-ray (CXR was normal but sonography of the abdomen readily demonstrated a large renal mass, later confirmed at biopsy as renal cell carcinoma (RCC. Clinicians should be cognizant of the strong association between digital acrometastases and renal cell carcinoma in male patients with normal CXR findings. In suspected hand acrometastasis associated with a soft tissue component outside the contours of normal bone, screening the abdomen by sonography should be done prior to bone biopsy and before costly or time-consuming investigations are offered. Metastatic RCC should be included in the differential diagnosis of all unilateral expansile bony lesions of the digit. It is particularly important if such lesion/lesions are accompanied by local inflammation. Screening the abdomen by sonography may be of particular value in such elderly male patient when Chest X-ray shows no abnormality.

  14. Occult intracranial injury in infants.

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    Greenes, D S; Schutzman, S A

    1998-12-01

    The objectives of this study were as follows: (1) to determine whether clinical symptoms and signs of brain injury are sensitive indicators of intracranial injury (ICI) in infants admitted with head trauma, (2) to describe the clinical characteristics of infants who have ICI in the absence of symptoms and signs of brain injury, and (3) to determine the clinical significance of those ICIs diagnosed in asymptomatic infants. We conducted a retrospective analysis of all infants younger than 2 years of age admitted to a tertiary care pediatric hospital with acute ICI during a 6(1/2)-year period. Infants were considered symptomatic if they had loss of consciousness, history of behavior change, seizures, vomiting, bulging fontanel, retinal hemorrhages, abnormal neurologic examination, depressed mental status, or irritability. All others were considered to have occult ICI. Of 101 infants studied, 19 (19%; 95% confidence interval [CI] 12%, 28%) had occult ICI. Fourteen of 52 (27%) infants younger than 6 months of age had occult ICI, compared with 5 of 34 (15%) infants 6 months to 1 year, and none of 15 (0%) infants older than 1 year. Eighteen (95%) infants with occult ICI had scalp contusion or hematoma, and 18 (95%) had skull fracture. Nine (47%) infants with occult ICI received therapy for the ICI. No infants with occult ICI (0%) (95% CI 0, 14%) required surgery or medical management for increased intracranial pressure. Only 1 subject (5%) with occult ICI had any late symptoms or complications: a brief, self-limited convulsion. We found that 19 of 101 ICIs in infants admitted with head trauma were clinically occult. All 19 occult ICIs occurred in infants younger than 12 months of age, and 18 of 19 had skull fractures. None experienced serious neurologic deterioration or required surgical intervention. Physicians cannot depend on the absence of clinical signs of brain injury to exclude ICI in infants younger than 1 year of age.

  15. Titan's zonal winds in its lower stratosphere

    Science.gov (United States)

    Flasar, F. Michael; Schinder, Paul J.

    2016-10-01

    Titan's atmosphere near 80 km (20 mbar) marks the transition between lower altitudes, where radiative damping times are large and seasonal variations are muted, and higher higher altitudes, where the damping times are much smaller and temperatures and winds vary significantly over the year. Cassini radio occultation soundings at high northern latitudes in winter have indicated a sharp transition from a highly stable temperature profile in the lower stratosphere to a layer between 80 and 100 km where temperatures decrease with altitude. The cause of this destabilization may be associated with the enhanced infrared opacity of a cloud of organic ices. It is curious that 20 mbar is also the level where the Doppler Wind Experiment on the Huygens Probe at 10° S observed a deep minimum in the zonal wind profile. Application of the gradient wind relation to the altitude-pressure profiles obtained from the Cassini radio occultation soundings have shown that this minimum is global. More recent soundings, obtained as Titan's southern hemisphere moves toward winter, indicate that this structure persists. The cause of this peculiar behavior is not really understood, but the the deceleration of the zonal winds observed in the lower stratosphere may be caused by radiative damping of vertically propagating atmospheric waves in a region where the damping time decreases rapidly with altitude.

  16. Detection of single-phase CTA occult vessel occlusions in acute ischemic stroke using CT perfusion-based wavelet-transformed angiography

    Energy Technology Data Exchange (ETDEWEB)

    Kunz, Wolfgang G.; Sommer, Wieland H.; Meinel, Felix G.; Ertl-Wagner, Birgit; Thierfelder, Kolja M. [Ludwig-Maximilian-University Hospital Munich, Institute for Clinical Radiology, Munich (Germany); Havla, Lukas; Dietrich, Olaf [Ludwig-Maximilian-University Hospital Munich, Josef Lissner Laboratory for Biomedical Imaging of the Institute for Clinical Radiology, Munich (Germany); Dorn, Franziska [Ludwig-Maximilian-University Hospital Munich, Department of Neuroradiology, Munich (Germany); Buchholz, Grete [Ludwig-Maximilian-University Hospital Munich, Department of Neurology, Munich (Germany)

    2017-06-15

    To determine the detection rate of intracranial vessel occlusions using CT perfusion-based wavelet-transformed angiography (waveletCTA) in acute ischemic stroke patients, in whom single-phase CTA (spCTA) failed to detect an occlusion. Subjects were selected from a cohort of 791 consecutive patients who underwent multiparametric CT including whole-brain CT perfusion. Inclusion criteria were (1) significant cerebral blood flow (CBF) deficit, (2) no evidence of vessel occlusion on spCTA and (3) follow-up-confirmed acute ischemic infarction. waveletCTA was independently analysed by two readers regarding presence and location of vessel occlusions. Logistic regression analysis was performed to identify predictors of waveletCTA-detected occlusions. Fifty-nine patients fulfilled the inclusion criteria. Overall, an occlusion was identified using waveletCTA in 31 (52.5 %) patients with negative spCTA. Out of 47 patients with middle cerebral artery infarction, 27 occlusions (57.4 %) were detected by waveletCTA, mainly located in the M2 (15) and M3 segments (8). The presence of waveletCTA-detected occlusions was associated with larger CBF deficit volumes (odds ratio (OR) = 1.335, p = 0.010) and shorter times from symptom onset (OR = 0.306, p = 0.041). waveletCTA is able to detect spCTA occult vessel occlusions in about half of acute ischemic stroke patients and may potentially identify more patients eligible for endovascular therapy. (orig.)

  17. Ozone zonal asymmetry and planetary wave characterization during Antarctic spring

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    I. Ialongo

    2012-03-01

    Full Text Available A large zonal asymmetry of ozone has been observed over Antarctica during winter-spring, when the ozone hole develops. It is caused by a planetary wave-driven displacement of the polar vortex. The total ozone data by OMI (Ozone Monitoring Instrument and the ozone profiles by MLS (Microwave Limb Sounder and GOMOS (Global Ozone Monitoring by Occultation of Stars were analysed to characterize the ozone zonal asymmetry and the wave activity during Antarctic spring. Both total ozone and profile data have shown a persistent zonal asymmetry over the last years, which is usually observed from September to mid-December. The largest amplitudes of planetary waves at 65° S (the perturbations can achieve up to 50% of zonal mean values is observed in October. The wave activity is dominated by the quasi-stationary wave 1 component, while the wave 2 is mainly an eastward travelling wave. Wave numbers 1 and 2 generally explain more than the 90% of the ozone longitudinal variations. Both GOMOS and MLS ozone profile data show that ozone zonal asymmetry covers the whole stratosphere and extends up to the altitudes of 60–65 km. The wave amplitudes in ozone mixing ratio decay with altitude, with maxima (up to 50% below 30 km.

    The characterization of the ozone zonal asymmetry has become important in the climate research. The inclusion of the polar zonal asymmetry in the climate models is essential for an accurate estimation of the future temperature trends. This information might also be important for retrieval algorithms that rely on ozone a priori information.

  18. The Occult Today: Why?

    Science.gov (United States)

    Kessler, Gary E.

    1975-01-01

    Author offered some reflections on the "why" of the contemporary interest in the occult. He attempted to convince the reader that, if he or she has been surprised by the recent rise of occultism, sober reflection will dispell some fears and, perhaps, even convince him or her that occultism is not merely superstition. (Author/RK)

  19. Saturation of Zonal Flows

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    Kim, Eun-Jin

    2002-11-01

    Zonal flows (ZF) are generated by drift wave (DW) turbulence and then regulate it near marginality by shear suppression. Since collisions damp ZF while ZF suppress DW, the amplitude of DW turbulence (i.e. turbulent transport) is, in turn, proportional to collisionality. A key question is then what happens away from marginality, namely what is the saturation mechanism of ZF in that regime? This raises the interesting physical question of how ZF interact with mne 0, poloidally non-axisymmetric modes [1], both linearly and non linearly. We investigate this issue by exploring the nonlinear excitation of GKH modes by modulational instability in the background of finite amplitude of DW turbulence, as well as the linear inflection-type instability of ZF. In a simple model with cold ions, we show that ZF can grow faster than the linear GKH for γ/ωGKH modes can be comparable to their linear generation. Here, γ and ω are the growth rate and frequency of DW, and p and k are the characteristic wavenumbers of ZF and DW. These findings imply that the linear analysis of GKH may not always be valid and also that there may be no clear distinction between secondary (ZF) and tertiary mode (GKH). The effect of finite ion temperature fluctuations is incorporated in a simple toroidal ion temperature gradient model, within which both zonal flow and temperature are generated by modulational instability. The phase between the two is calculated self-consistently and shown to be positive. Furthermore, the correction to nonlinear generation of GKH modes appears to be small. [1] We refer to these low mne 0 modes as Generalized Kelvin-Helmholtz (GKH) modes, since they will appear as mne 0 distortions of a shear layer.

  20. Zonal flows as statistical equilibria

    CERN Document Server

    Bouchet, F

    2016-01-01

    Zonal jets are striking and beautiful examples of the propensity for geophysical turbulent flows to spontaneously self-organize into robust, large scale coherent structures. There exist many dynamical mechanisms for the formation of zonal jets: statistical theories (kinetic approaches, second order or larger oder closures), deterministic approaches (modulational instability, $\\beta$-plumes, radiating instability, zonostrophic turbulence, and so on). A striking remark is that all these different dynamical approaches, each of them possibly relevant in some specific regimes, lead to the same kind of final jet structures. Is it then possible to have a more general explanation of why all these different dynamical regimes, from fully turbulent flows to gentle quasilinear regime, consistently lead to the same jet attractors ? Equilibrium statistical mechanics provides an answer to this general question. Here we we present the salient features of this theory and review applications of this approach to the description...

  1. Occult hepatitis B virus and hepatitis C virus infections.

    Science.gov (United States)

    Carreño, Vicente; Bartolomé, Javier; Castillo, Inmaculada; Quiroga, Juan Antonio

    2008-01-01

    Occult HBV infection is a well-recognised clinical entity characterised by the detection of HBV-DNA in serum and/or in liver in the absence of detectable hepatitis B surface antigen (HBsAg). Occult HBV infection has been described not only in patients who have resolved an acute or chronic HBV infection but also in patients without any serological markers of a past HBV infection. Occult HBV infection in patients with chronic HCV infection may induce more severe liver disease and lower response rate to interferon treatment. The existence of occult HCV infections has been also reported more recently. Occult HCV infection is characterised by the presence of HCV-RNA in liver and peripheral blood mononuclear cells in the absence of detectable serum HCV-RNA. Occult HCV infection may occur under two different clinical situations: in hepatitis C antibody-(anti-HCV) negative and serum HCV-RNA-negative patients with abnormal liver function tests and in anti-HCV-positive patients who have no detectable serum HCV-RNA and who have normal liver enzymes. The clinical relevance of occult HCV infections is still under investigation.

  2. Occult intrasacral meningoceles

    Energy Technology Data Exchange (ETDEWEB)

    Vogelsang, H.

    1985-03-01

    The author reports on 8 patients with cystic enlargements of the canalis sacralis (occult intrasacral maningocele). The clinical pattern of signs, x-ray findings (plain radiography, myelography, computed tomography) and possible treatment are discussed in comparison with the cases published to date.

  3. Zonal flow formation in the Earth's core.

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    Miyagoshi, Takehiro; Kageyama, Akira; Sato, Tetsuya

    2010-02-11

    Zonal jets are very common in nature. Well-known examples are those in the atmospheres of giant planets and the alternating jet streams found in the Earth's world ocean. Zonal flow formation in nuclear fusion devices is also well studied. A common feature of these zonal flows is that they are spontaneously generated in turbulent systems. Because the Earth's outer core is believed to be in a turbulent state, it is possible that there is zonal flow in the liquid iron of the outer core. Here we report an investigation at the current low-viscosity limit of numerical simulations of the geodynamo. We find a previously unknown convection regime of the outer core that has a dual structure comprising inner, sheet-like radial plumes and an outer, westward cylindrical zonal flow. We numerically confirm that the dual-convection structure with such a zonal flow is stable under a strong, self-generated dipole magnetic field.

  4. On radial geodesic forcing of zonal modes

    OpenAIRE

    Kendl, Alexander

    2011-01-01

    The elementary local and global influence of geodesic field line curvature on radial dispersion of zonal modes in magnetised plasmas is analysed with a primitive drift wave turbulence model. A net radial geodesic forcing of zonal flows and geodesic acoustic modes can not be expected in any closed toroidal magnetic confinement configuration, since the flux surface average of geodesic curvature identically vanishes. Radial motion of poloidally elongated zonal jets may occur in the presence of g...

  5. On radial geodesic forcing of zonal modes

    CERN Document Server

    Kendl, Alexander

    2011-01-01

    The elementary local and global influence of geodesic field line curvature on radial dispersion of zonal modes in magnetised plasmas is analysed with a primitive drift wave turbulence model. A net radial geodesic forcing of zonal flows and geodesic acoustic modes can not be expected in any closed toroidal magnetic confinement configuration, since the flux surface average of geodesic curvature identically vanishes. Radial motion of poloidally elongated zonal jets may occur in the presence of geodesic acoustic mode activity. Phenomenologically a radial propagation of zonal modes shows some characteristics of a classical analogon to second sound in quantum condensates.

  6. Occult Macular Dystrophy

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    Işıl Sayman Muslubaş

    2016-04-01

    Full Text Available Occult macular dystrophy is an inherited macular dystrophy characterized by a progressive decline of bilateral visual acuity with normal fundus appearance, fluorescein angiogram and full-field electroretinogram. This case report presents a 20-year-old female patient with bilateral progressive decline of visual acuity for six years. Her visual acuity was 3-4/10 in both eyes. Anterior segment and fundus examination, fluorescein angiogram and full-field electroretinogram were normal. She could read all Ishihara pseudoisochromatic plates. Fundus autofluorescence imaging was normal. There was a mild central hyporeflectance on fundus infrared reflectance imaging in both eyes. Reduced foveal thickness and alterations of the photoreceptor inner and outer segment junction were observed by optical coherence tomography in both eyes. Central scotoma was also found by microperimetry and reduced central response was revealed by multifocal electroretinogram in both eyes. These findings are consistent with the clinical characteristics of occult macular dystrophy

  7. Zonal displacement of western Pacific warm pool and zonal wind anomaly over the Pacific Ocean

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The thermal condition anomaly of the western Pacific warm pool and its zonal displacement have very important influences on climate change in East Asia and even the whole world.However, the impact of the zonal wind anomaly over the Pacific Ocean on zonal displacement of the warm pool has not yet been analyzed based on long-term record. Therefore, it is important to study the zonal displacement of the warm pool and its response to the zonal wind anomaly over the equatorial Pacific Ocean. Based on the NCDC monthly averaged SST (sea surface temperature) data in 2°×2° grid in the Pacific Ocean from 1950 to 2000, and the NCEP/NCAR global monthly averaged 850 hPa zonal wind data from 1949 to 2000, the relationships between zonal displacements of the western Pacific warm pool and zonal wind anomalies over the tropical Pacific Ocean are analyzed in this paper. The results show that the zonal displacements are closely related to the zonal wind anomalies over the western, central and eastern equatorial Pacific Ocean. Composite analysis indicates that during ENSO events, the warm pool displacement was trigged by the zonal wind anomalies over the western equatorial Pacific Ocean in early stage and the process proceeded under the zonal wind anomalies over the central and eastern equatorial Pacific Ocean unless the wind direction changes. Therefore, in addition to the zonal wind anomaly over the western Pacific, the zonal wind anomalies over the central and eastern Pacific Ocean should be considered also in investigation the dynamical mechanisms of the zonal displacement of the warm pool.

  8. Venous thromboembolism and occult cancer: impact on clinical practice.

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    Gheshmy, Afshan; Carrier, Marc

    2016-04-01

    Unprovoked venous thromboembolism (VTE) can be the first manifestation of cancer. Given this relationship between unprovoked VTE and cancer, it is appealing for clinicians to screen their patients with a first episode of acute unprovoked VTE for a potential occult malignancy. Five different studies have compared a limited (thorough history and physical exam, basic bloodwork) to a more extensive occult cancer screening strategy (e.g. computed tomography, fludeoxyglucose positron emission tomography, etc.). Most of these studies have failed to show that an extensive occult cancer screening strategy diagnoses more occult cancer (including early cancers), misses fewer cancers during follow-up or improves overall and/or cancer-related mortality suggesting that extensive occult cancer screening should not be performed routinely. Therefore, patients with a first unprovoked VTE should undergo a limited cancer screening only and clinicians should ensure that their patients are up to date regarding age- and gender- specific cancer screening (colon, breast, cervix and prostate) as per their national recommendations. Current evidence does not support a net clinical benefit to perform an extensive occult cancer screening on all patients, and a decision to do additional testing should be made on a case by case basis.

  9. On the influence of zonal gravity wave distributions on the Southern Hemisphere winter circulation

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    Lilienthal, Friederike; Jacobi, Christoph; Schmidt, Torsten; de la Torre, Alejandro; Alexander, Peter

    2017-07-01

    A mechanistic global circulation model is used to simulate the Southern Hemisphere stratospheric, mesospheric, and lower thermospheric circulation during austral winter. The model includes a gravity wave (GW) parameterization that is initiated by prescribed 2-D fields of GW parameters in the troposphere. These are based on observations of GW potential energy calculated using GPS radio occultations and show enhanced GW activity east of the Andes and around the Antarctic. In order to detect the influence of an observation-based and thus realistic 2-D GW distribution on the middle atmosphere circulation, we perform model experiments with zonal mean and 2-D GW initialization, and additionally with and without forcing of stationary planetary waves (SPWs) at the lower boundary of the model. As a result, we find additional forcing of SPWs in the stratosphere, a weaker zonal wind jet in the mesosphere, cooling of the mesosphere and warming near the mesopause above the jet. SPW wavenumber 1 (SPW1) amplitudes are generally increased by about 10 % when GWs are introduced being longitudinally dependent. However, at the upper part of the zonal wind jet, SPW1 in zonal wind and GW acceleration are out of phase, which reduces the amplitudes there.

  10. DETECTION OF OCCULT GLOMERULAR DYSFUNCTION IN GLUCOSE SIX PHOSPHATE DEHYDROGENASE DEFICIENCY ANEMIA

    Directory of Open Access Journals (Sweden)

    Gehan Abdel Hakeem

    2016-08-01

    G6PD deficiency anemia is associated with a variable degree of glomerular dysfunction during acute hemolytic episodes. This glomerular dysfunction can result in chronic subclinical or occult chronic kidney injury.

  11. The occult urothelial cancer.

    Science.gov (United States)

    Ragonese, Mauro; Racioppi, Marco; D'Agostino, Daniele; Di Gianfrancesco, Luca; Lenci, Niccolò; Bientinesi, Riccardo; Palermo, Giuseppe; Sacco, Emilio; Pinto, Francesco; Bassi, Pier Francesco

    2016-05-24

    Transitional cell carcinoma (TCC) is the tumor that most frequently affects the urinary tract. The most common location is in the bladder; the diagnosis, as the follow-up, is based on urine cytology, endoscopic, and radiological examinations. Urinary cytology is an important non invasive tool used in the diagnosis and follow-up of patients with TCC. A positive urine cytology result is highly predictive of the presence of TCC, even in the presence of normal cystoscopy, because malignant cells may appear in the urine long time before any cystoscopically visible lesion becomes apparent. The presence of a positive urinary cytology, in the absence of clinical or endoscopic evidence of a TCC, can identify an occult urothelial cancer, located in any site of the urinary tract (upper urinary tract, bladder, prostatic urethra). Most of the urothelial tumors of the renal pelvis and ureters are diagnosed by radiological examinations, but we can observe a high rate of false negatives. In order to improve the diagnostic role of urinary cytology and other conventional examinations, numerous molecular markers have been identified; however, the real clinical application remains unclear. Photodynamic diagnosis and narrow band imaging (NBI) cystoscopy increase the diagnostic accuracy of endoscopic examinations in the presence of lesions not easily detectable. The aim of this review is to analyze the current diagnostic standards in the presence of occult urothelial cancer.

  12. Kuiper Belt Occultation Predictions

    CERN Document Server

    Fraser, Wesley C; Trujillo, Chad; Stephens, Andrew W; Kavelaars, JJ; Brown, Michael E; Bianco, Federica B; Boyle, Richard P; Brucker, Melissa J; Hetherington, Nathan; Joner, Michael; Keel, William C; Langill, Phil P; Lister, Tim; McMillan, Russet J; Young, Leslie

    2013-01-01

    Here we present observations of 7 large Kuiper Belt Objects. From these observations, we extract a point source catalog with $\\sim0.01"$ precision, and astrometry of our target Kuiper Belt Objects with $0.04-0.08"$ precision within that catalog. We have developed a new technique to predict the future occurrence of stellar occultations by Kuiper Belt Objects. The technique makes use of a maximum likelihood approach which determines the best-fit adjustment to cataloged orbital elements of an object. Using simulations of a theoretical object, we discuss the merits and weaknesses of this technique compared to the commonly adopted ephemeris offset approach. We demonstrate that both methods suffer from separate weaknesses, and thus, together provide a fair assessment of the true uncertainty in a particular prediction. We present occultation predictions made by both methods for the 7 tracked objects, with dates as late as 2015. Finally, we discuss observations of three separate close passages of Quaoar to field star...

  13. The Halogen Occultation Experiment

    Science.gov (United States)

    Russell, James M., III; Gordley, Larry L.; Park, Jae H.; Drayson, S. R.; Hesketh, W. D.; Cicerone, Ralph J.; Tuck, Adrian F.; Frederick, John E.; Harries, John E.; Crutzen, Paul J.

    1993-01-01

    The Halogen Occultation Experiment (HALOE) uses solar occultation to measure vertical profiles of O3, HCl, HF, CH4, H2O, NO, NO2, aerosol extinction, and temperature versus pressure with an instantaneous vertical field of view of 1.6 km at the earth limb. Latitudinal coverage is from 80 deg S to 80 deg N over the course of 1 year and includes extensive observations of the Antarctic region during spring. The altitude range of the measurements extends from about 15 km to about 60-130 km, depending on channel. Experiment operations have been essentially flawless, and all performance criteria either meet or exceed specifications. Internal data consistency checks, comparisons with correlative measurements, and qualitative comparisons with 1985 atmospheric trace molecule spectroscopy (ATMOS) results are in good agreement. Examples of pressure versus latitude cross sections and a global orthographic projection for the September 21 to October 15, 1992, period show the utility of CH4, HF, and H2O as tracers, the occurrence of dehydration in the Antarctic lower stratosphere, the presence of the water vapor hygropause in the tropics, evidence of Antarctic air in the tropics, the influence of Hadley tropical upwelling, and the first global distribution of HCl, HF, and NO throughout the stratosphere. Nitric oxide measurements extend through the lower thermosphere.

  14. Occult pneumothorax, revisited

    Directory of Open Access Journals (Sweden)

    Mangar Devanand

    2010-10-01

    Full Text Available Abstract Pneumothorax is a recognized cause of preventable death following chest wall trauma where a simple intervention can be life saving. In cases of trauma patients where cervical spine immobilization is mandatory, supine AP chest radiograph is the most practical initial study. It is however not as sensitive as CT chest for early detection of a pneumothorax. "Occult" pneumothorax is an accepted definition of an existing but usually a clinically and radiologically silent disturbance that in most patients can be tolerated while other more urgent trauma needs are attended to. However, in certain patients, especially those on mechanical ventilation (with subsequent increase of intrapleural air with positive pressure ventilation, missing the diagnosis of pneumothorax can be deleterious with fatal consequences. This review will discuss the occult pneumothorax in the context of 3 radiological examples, which will further emphasize the entity. Because a negative AP chest radiograph can dangerously delay its recognition, we recommend that any trauma victim presenting to the emergency department with symptoms of respiratory distress should be screened with either thoracic ultrasonography or chest CT scan to avoid missing a pneumothorax.

  15. Patients with hepatocellular carcinoma related to prior acute arsenic intoxication and occult HBV: Epidemiological, clinical and therapeutic results after 14 years of follow-up

    Institute of Scientific and Technical Information of China (English)

    Teresa Casanovas-Taltavull; Josepa Ribes; Ana Berrozpe; Sara Jordan; Aurora Casanova; Concha Sancho; Carles Valls; F Xavier Bosch

    2006-01-01

    Little is known about the long-term survivors of acute arsenic intoxication. We present here a clinical case report of a man with chronic hepatitis B virus (HBV) infection who developed hepatocellular carcinoma four years after acute arsenic poisoning. HBsAg was detected in serum in 1990 when he voluntarily donated blood.In 1991, the patient suffered from severe psychological depression that led him to attempt suicide by massive ingestion of an arsenic-containing rodenticide. He survived with polyneuropathy and paralysis of the lower limbs, and has been wheelchair-bound since then. During participation in a follow-up study conducted among HBV carriers, abdominal ultrasound detected a two-centimeter liver mass consistent with hepatocellular carcinoma. The tumor was confirmed by computed tomography (CT) and magnetic resonance image (MRI). Because of his significant comorbidity, the patient received palliative treatment with transarterial lipiodol chemoembolization (TACE) on three occasions (1996, 1997 and 1999).At his most recent visit in May 2005, the patient was asymptomatic, liver enzymes were normal and the tumor was in remission on ultrasound.

  16. The Occult: Diabolica to Alchemists

    Science.gov (United States)

    Delaney, Oliver J.

    1971-01-01

    The 91 items in this bibliography deal with works of occult science. The material is subdivided into biographies, dictionaries, encyclopedias, handbooks, noteworthy histories, indices, annuals, and a few miscellany works with treatises. (95 references) (Author)

  17. [Occult hepatitis C virus infection].

    Science.gov (United States)

    Carreño García, Vicente; Nebreda, Javier Bartolomé; Aguilar, Inmaculada Castillo; Quiroga Estévez, Juan Antonio

    2011-03-01

    Occult hepatitis C virus (HCV) infection is characterized by the detection of HCV-RNA in liver in the absence of anti-HCV and serum HCV-RNA determined by conventional techniques. The development of a new enzyme immunoassay for the detection of antibodies against a conserved epitope in the HCV core protein, together with the detection of HCV-RNA in peripheral blood mononuclear cells and in serum after concentrating the viral particles by ultracentrifugation, allow diagnosis of more than 90% of patients with occult HCV without the need to perform a liver biopsy. Histological damage in occult HCV infection ranges from minimal changes to liver cirrhosis and hepatocellular carcinoma, although in general this disease is less severe than classical chronic hepatitis C. A significant prevalence of occult HCV infection has been identified in risk groups such as hemodialysis patients and the family members of patients with occult hepatitis C. This occult HCV infection can also be found in subjects without clinical or biochemical evidence of liver disease. Copyright © 2011 Elsevier España S.L. All rights reserved.

  18. Emergence of non-zonal coherent structures

    CERN Document Server

    Bakas, Nikolaos A

    2015-01-01

    Planetary turbulence is observed to self-organize into large-scale structures such as zonal jets and coherent vortices. One of the simplest models that retains the relevant dynamics of turbulent self-organization is a barotropic flow in a beta-plane channel with turbulence sustained by random stirring. Non-linear integrations of this model show that as the energy input rate of the forcing is increased, the homogeneity of the flow is first broken by the emergence of non-zonal, coherent, westward propagating structures and at larger energy input rates by the emergence of zonal jets. The emergence of both non-zonal coherent structures and zonal jets is studied using a statistical theory, Stochastic Structural Stability Theory (S3T). S3T directly models a second-order approximation to the statistical mean turbulent state and allows the identification of statistical turbulent equilibria and study of their stability. Using S3T, the bifurcation properties of the homogeneous state in barotropic beta-plane turbulence ...

  19. Anisotropic electrostatic turbulence and zonal flow generation

    Energy Technology Data Exchange (ETDEWEB)

    Balescu, R [Physique Statistique-Plasmas, Association Euratom-Etat Belge, Universite Libre de Bruxelles, Campus Plaine, Bd. du Triomphe, 1050 Bruxelles (Belgium); Petrisor, I [Department of Physics, Association Euratom-MEdC, Romania, University of Craiova, 13 A.I.Cuza Str., 200585 Craiova (Romania); Negrea, M [Department of Physics, Association Euratom-MEdC, Romania, University of Craiova, 13 A.I.Cuza Str., 200585 Craiova (Romania)

    2005-12-15

    In this paper we analyse the running and asymptotic diffusion coefficients of a plasma in the case of zonal flow generation by an anisotropic stochastic electrostatic potential. Both the weak and relatively strong turbulence regimes were analysed. The analysis of the diffusion coefficients in wave vector space provides an illustration of the fragmentation of drift wave structures in the radial direction and the generation of long-wavelength structures in the poloidal direction that are identified as zonal flows. We have shown that the fragmentation of drift wave structures is strongly influenced by the anisotropy parameter, the electrostatic Kubo number and by the initial values of the wave vector.

  20. Home Use Tests: Fecal Occult Blood

    Science.gov (United States)

    ... Procedures In Vitro Diagnostics Home Use Tests Fecal Occult Blood Share Tweet Linkedin Pin it More sharing ... test kit to measure the presence of hidden (occult) blood in your stool (feces). What is fecal ...

  1. Testing for Occult Heartworm Infection

    Science.gov (United States)

    Stogdale, L.

    1984-01-01

    Heartworm infection in dogs is endemic in southern Ontario but occurs only sporadically throughout the remainder of Canada. The disease may either be associated with microfilariae in the patient's blood, a patent infection, or it may be occult. This paper describes a case of occult dirofilariasis in a dog, with emphasis on the diagnosis. A patent infection could be missed if the clinician tests an insufficient amount of blood. He should perform multiple concentration tests using either the modified Knott's technique or a filtration method. Occult infections occur in prepatent or unisexual infections, when the worms become sterile following therapy, or when the host produces antibodies that result in the destruction of the microfilariae. The recent release of a kit which detects the presence of antibodies to the adult heartworms now enables veterinarians to make an accurate diagnosis in the vast majority of dogs. PMID:17422386

  2. Occult Participation: Its Impact on Adolescent Development.

    Science.gov (United States)

    Tennant-Clark, Cynthia M.; And Others

    1989-01-01

    Investigated relationship between occult participation, substance abuse, and level of self-esteem among 25 clinical (alcohol or drug treatment) and 25 nonclinical adolescents. Results indicated that adolescent substance abuse and occult participation were significantly related. Found significant differences between high versus low occult groups…

  3. MRI of radiographically occult ischial apophyseal avulsions

    Energy Technology Data Exchange (ETDEWEB)

    Meyers, Arthur B. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, MLC 5031, Cincinnati, OH (United States); Children' s Hospital of Wisconsin, Milwaukee, WI (United States); Laor, Tal; Zbojniewicz, Andrew M.; Anton, Christopher G. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, MLC 5031, Cincinnati, OH (United States)

    2012-11-15

    Acute avulsions of unossified ischial apophyses in children may go undetected on radiography. Therapy includes rest and rehabilitation; however, substantial displacement may require surgery. Our purpose is to illustrate the utility of MRI in the detection of these radiographically occult injuries in skeletally immature children. This retrospective study of more than 5 years included children with ischial avulsions who were evaluated with both radiography and MRI within 3 weeks of acute injury. Initially, radiographs were reviewed to identify those children with unossified ischial apophyses. Subsequently, their MRI examinations were assessed for physeal disruption, bone/soft tissue edema, periosteal/perichondrial elevation and disruption. Initial and follow-up radiographs (if available) were reviewed. Patient age, symptoms and offending activity were determined from clinical records. Five children met inclusion criteria. All initial radiographs were normal. MRI showed: edema (n = 5), periosteal elevation (n = 4), periosteal/perichondrial disruption (n = 4), >5.5 mm displacement (n = 0). Follow-up radiographs in two children (2 and 2.5 months from MRI) showed osseous ischial irregularity. The apophyses remained unossified. Acute unossified ischial apophyseal avulsions in children may be radiographically undetected. In the setting of correlative clinical symptoms, MRI can be used to identify these injuries and to help direct appropriate therapy. (orig.)

  4. Generalized Quasilinear Approximation: Application to Zonal Jets

    Science.gov (United States)

    Marston, J. B.; Chini, G. P.; Tobias, S. M.

    2016-05-01

    Quasilinear theory is often utilized to approximate the dynamics of fluids exhibiting significant interactions between mean flows and eddies. We present a generalization of quasilinear theory to include dynamic mode interactions on the large scales. This generalized quasilinear (GQL) approximation is achieved by separating the state variables into large and small zonal scales via a spectral filter rather than by a decomposition into a formal mean and fluctuations. Nonlinear interactions involving only small zonal scales are then removed. The approximation is conservative and allows for scattering of energy between small-scale modes via the large scale (through nonlocal spectral interactions). We evaluate GQL for the paradigmatic problems of the driving of large-scale jets on a spherical surface and on the beta plane and show that it is accurate even for a small number of large-scale modes. As GQL is formally linear in the small zonal scales, it allows for the closure of the system and can be utilized in direct statistical simulation schemes that have proved an attractive alternative to direct numerical simulation for many geophysical and astrophysical problems.

  5. 21 CFR 864.6550 - Occult blood test.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Occult blood test. 864.6550 Section 864.6550 Food... DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Manual Hematology Devices § 864.6550 Occult blood test. (a) Identification. An occult blood test is a device used to detect occult blood in urine or feces. (Occult blood...

  6. ZonalMetrics - a Python toolbox for zonal landscape structure analysis

    Science.gov (United States)

    Adamczyk, Joanna; Tiede, Dirk

    2017-02-01

    We present a Python toolbox for the calculation of zonal landscape metrics. Instead of global calculations focusing on the whole landscape, the proposed ZonalMetrics toolbox allows the calculation of landscape metrics for user-defined zones. Such zones can be defined through regular units (e.g. hexagons, grids) that can be created within the toolbox. In addition, any polygonal set specified by the user (e.g. administrative units) can be used. The implemented set of landscape metrics is specifically selected and valid for calculations within zones. The tool is demonstrated based on a case study for the Warsaw metropolitan area and the possibilities of applying the toolbox for different zonal layers are illustrated. The implementation is based on the Python toolbox introduced in ArcGIS 10.1, offering an easy to use graphical user interface and batch calculation possibilities. The source code is free and open to the community and extendable to specific needs.

  7. Occult HBV infection and HCC

    Directory of Open Access Journals (Sweden)

    Isabelle Chemin

    2007-02-01

    Full Text Available

    A number of risk factors appear to play a role in Hepatocellularcinoma (HCC, HBV infection being one of the most important. Chronic inflammation and cytokines are key determinants in the development of fibrosis and liver cell proliferation. HBV DNA integration into host cellular DNA, has been extensively studied and may disrupt or promote expression of cellular genes that are important in cell growth and differentiation. Moreover, expression of HBV proteins may have a direct effect on cellular functions, and some of these gene products may lead to malignant transformation. Several HBV genes have been frequently found in infected tissues including truncated pre-S2/S, hepatitis B X gene, and a novel spliced transcript of HBV (hepatitis B spliced protein. The proteins expressed from these integrated genes have been shown to have intracellular activities, including effects on cellular growth and apoptosis. Occult hepatitis B virus (HBV infection is characterized by persistence of HBV DNA into the tissue of hep atitis B surface antigen-negative individuals. The clinical relevance of this peculiar infection, in particular, the impact of occult HBV infection in cases of HCC has been a matter of debate. Prevalence and molecular status of occult HBV in patients with HCC has been investigated in several studies. HCC patients from Italy, France, Japan, Morocco, the United States, Canada etc…..who had no detectable HBsAg in their serum have been studied. In these HBsAg-negative HCC patients, HBV DNA was detected in tumorous and/or in adjacent non tumorous liver tissue using polymerase chain reaction (PCR in almost half of the patients, being anti-HCV positive or not. Some of the patients are positive for anti-HBc antibodies as the only marker of HBV infection, but not all. Covalently closed circular HBV DNA may be detected indicating that at least some of these patients

  8. IUVS/MAVEN Stellar Occultations

    Science.gov (United States)

    Gröller, Hannes; Yelle, Roger; Montmessin, Franck; Lacombe, Gaetan; Schneider, Nicholas M.; Deighan, Justin; Jain, Sonal; Nakagawa, Hiromu; Jakosky, Bruce

    2016-10-01

    We present the latest results from stellar occultations observed with the Imaging Ultraviolet Spectrograph (IUVS) instrument on board of Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. So far 9 campaigns have been executed on average every two months since MAVEN began orbiting Mars. Approximately 50 occultations are recorded in each campaign. The IUVS instrument observes in two spectral regions, the far- and mid-UV. The FUV channel covers wavelengths from 110 to 190 nm and the MUV channel from 170 to 350 nm. By combining those two channels we cover the whole altitude range starting from around 30 km to 150 km. We present the geometric dependent CO2, O2, and O3 number densities from these occultations. The derived O2 mixing ratio varies between 1.5 × 10-3 and 5 × 10-3. In some of the MUV occultations we also can see aerosol extinction. In addition we present temperatures derived from the CO2 densities assuming hydrostatic equilibrium. We retrieved mean temperatures of around 180 K at lower altitudes, which decreasing with altitudes down to a mean of around 130 K at higher altitudes. We see a constantly cold layer with temperatures of 105 – 120 K at a pressure level at roughly 7 × 10-6 Pa, equivalent to an altitude of around 140 km. We also discuss possible wave structures with amplitudes between 5 and 15 K and wavelengths between 10 and 15 km in the obtained temperature profiles. The temperature profiles, retrieved with the IUVS instrument, are mostly in agreement with predicted values from the Mars Climate Database model, except where we see the cold layer around 140 km.

  9. Linear zonal atmospheric prediction for adaptive optics

    Science.gov (United States)

    McGuire, Patrick C.; Rhoadarmer, Troy A.; Coy, Hanna A.; Angel, J. Roger P.; Lloyd-Hart, Michael

    2000-07-01

    We compare linear zonal predictors of atmospheric turbulence for adaptive optics. Zonal prediction has the possible advantage of being able to interpret and utilize wind-velocity information from the wavefront sensor better than modal prediction. For simulated open-loop atmospheric data for a 2- meter 16-subaperture AO telescope with 5 millisecond prediction and a lookback of 4 slope-vectors, we find that Widrow-Hoff Delta-Rule training of linear nets and Back- Propagation training of non-linear multilayer neural networks is quite slow, getting stuck on plateaus or in local minima. Recursive Least Squares training of linear predictors is two orders of magnitude faster and it also converges to the solution with global minimum error. We have successfully implemented Amari's Adaptive Natural Gradient Learning (ANGL) technique for a linear zonal predictor, which premultiplies the Delta-Rule gradients with a matrix that orthogonalizes the parameter space and speeds up the training by two orders of magnitude, like the Recursive Least Squares predictor. This shows that the simple Widrow-Hoff Delta-Rule's slow convergence is not a fluke. In the case of bright guidestars, the ANGL, RLS, and standard matrix-inversion least-squares (MILS) algorithms all converge to the same global minimum linear total phase error (approximately 0.18 rad2), which is only approximately 5% higher than the spatial phase error (approximately 0.17 rad2), and is approximately 33% lower than the total 'naive' phase error without prediction (approximately 0.27 rad2). ANGL can, in principle, also be extended to make non-linear neural network training feasible for these large networks, with the potential to lower the predictor error below the linear predictor error. We will soon scale our linear work to the approximately 108-subaperture MMT AO system, both with simulations and real wavefront sensor data from prime focus.

  10. Occult Communications: On Instrumentation, Esotericism, and Epistemology

    Directory of Open Access Journals (Sweden)

    Bernard Dionysius Geoghegan

    2015-09-01

    Full Text Available Viewed from the perspective of the occult, formerly straight and narrow conduits of reason may even begin to resemble irregular relays composed of irregular twists and turns. This essay offers a brief overview of key literature on spiritualism and the occult, some larger reflections on the place of the occult within studies of science and communications, and brief summaries of the essays contained in this volume.

  11. OCCULT POWER AND AFRICA'S SOCIO-ECONOMIC PROBLEMS ...

    African Journals Online (AJOL)

    Dr Ike

    Occult powers are not provable by scientific experiments and experience. ... he possessed. African World View as Background to the Belief in Occult. Powers ..... on witchcraft and how to deal with it. What followed .... real occult power. Often the ...

  12. Scaling Relation for Occulter Manufacturing Errors

    Science.gov (United States)

    Sirbu, Dan; Shaklan, Stuart B.; Kasdin, N. Jeremy; Vanderbei, Robert J.

    2015-01-01

    An external occulter is a spacecraft own along the line-of-sight of a space telescope to suppress starlight and enable high-contrast direct imaging of exoplanets. The shape of an external occulter must be specially designed to optimally suppress starlight and deviations from the ideal shape due to manufacturing errors can result loss of suppression in the shadow. Due to the long separation distances and large dimensions involved for a space occulter, laboratory testing is conducted with scaled versions of occulters etched on silicon wafers. Using numerical simulations for a flight Fresnel occulter design, we show how the suppression performance of an occulter mask scales with the available propagation distance for expected random manufacturing defects along the edge of the occulter petal. We derive an analytical model for predicting performance due to such manufacturing defects across the petal edges of an occulter mask and compare this with the numerical simulations. We discuss the scaling of an extended occulter test-bed.

  13. Climate Prediction Center (CPC)Equatorial Zonally-Averaged 50-hPa Zonal Wind Anomalies

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is one of the CPC?s Monthly Atmospheric and SST Indices. It is the 50-hPa zonal wind anomalies averaged over the Equator. The anomalies are departures from the...

  14. Climate Prediction Center (CPC)Equatorial Zonally-averaged 30-hPa Zonal Wind Anomalies

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is one of the CPC?s Monthly Atmospheric and SST Indices. It is the 30-hPa zonal wind anomalies averaged over the Equator. The anomalies are departures from the...

  15. Currents, Geostrophic, Aviso, 0.25 degrees, Global, Zonal

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Aviso Zonal Geostrophic Current is inferred from Sea Surface Height Deviation, climatological dynamic height, and basic fluid mechanics.

  16. DYNAMICS OF THE ZONAL ASYMMETRIC STRUCTURE OF ARCTIC OSCILLATION

    Institute of Scientific and Technical Information of China (English)

    WANG Xiu-hong; YU Wei-dong; LUO Ti-qian

    2004-01-01

    The Arctic Oscillation(AO),though basically is a zonal symmetric phenomenon,also shows zonal asymmetric variation.The dynamics of this zonal variation is considered here from the point of view of the planetary propagation on the earth sphere.Based on the linear barotropic vorticity equation,the planetary wave ray path is calculated in the winter January.It shows that NAO(North Atlantic Oscillation),AO and North Pacific could be linked through the planetary wave propagation,which acts as the atmospheric bridge.The zonal symmetric and asymmetric structures both have association with these Rossby wave activities.

  17. Pathogenesis of occult chronic hepatitis B virus infection

    Institute of Scientific and Technical Information of China (English)

    Rocio Aller de la Fuente; María L Gutiérrez; Javier Garcia-Samaniego; Conrado Fernández-Rodriguez; Jose Luis Lledó; Gregorio Castellano

    2011-01-01

    Occult hepatitis B infection (OBI) is characterized by hepatitis B virus (HBV) DNA in serum in the absence of hepatitis B surface antigen (HBsAg) presenting HBsAg-negative and anti-HBc positive serological patterns. Occult HBV status is associated in some cases with mutant viruses undetectable by HBsAg assays; but more frequently it is due to a strong suppression of viral replication and gene expression. OBI is an entity with world-wide diffusion. The failure to detect HBsAg, despite the persistence of the viral DNA, is due in most cases to the strong suppression of viral replication and gene expression that characterizes this "occult" HBV infection; although the mechanisms responsible for suppression of HBV are not well understood. The majority of OBI cases are secondary to overt HBV infection and represent a residual low viremia level suppressed by a strong immune response together with histological derangements which occurred during acute or chronic HBV infection. Much evidence suggests that it can favour the progression of liver fibrosis and the development of hepatocellular carcinoma.

  18. Occult hemorrhage in children with severe ITP.

    Science.gov (United States)

    Flores, Adolfo; Buchanan, George R

    2016-03-01

    Little is known about the frequency and significance of clinically unapparent or occult hemorrhage in ITP. Therefore, we prospectively explored the sites and frequency of occult bleeding in children with severe ITP at diagnosis or upon symptomatic relapse in a prospective, single-institution cohort study of patients ≤ 18 years of age and a platelet count ≤ 10,000/mm(3) . Data collected included bleeding severity assessment, urinalysis, fecal occult blood testing, and non-contrast brain MRI. Stool and urine samples were tested within 7 days of diagnosis or symptomatic relapse. Three months after diagnosis or relapse a noncontrast brain MRI evaluated hemosiderin deposits resulting from prior localized hemorrhage. Fifty-two ITP patients were enrolled with a mean platelet count of 4,000/mm(3) . A significant occurrence of occult hemorrhage was identified in the urine (27%) compared with clinically overt hematuria (0.91%, P occult bleeding in the urinary tract. There was no relationship between occult hemorrhage and bleeding manifestations on physical examination. Occult hemorrhage was not a harbinger of subsequent bleeding. Our findings suggest that occult hemorrhage occurs with greater frequency than overt bleeding in children with severe ITP. CNS microbleeding is a potential risk in this patient population. Assessment of brain microbleeds and microscopic hematuria in this patient population require additional study.

  19. Occultations for probing atmosphere and climate

    CERN Document Server

    Foelsche, Ulrich; Steiner, Andrea

    2004-01-01

    Use of occultation methodology for observing the Earth's atmosphere and climate has become so broad as to comprise solar, lunar, stellar, navigation and satellite­ crosslink occultation methods. The atmospheric parameters obtained extend from the fundamental variables temperature, density, pressure, water vapor, and ozone via a multitude of trace gas species to particulate species such as aerosols and cloud liquid water. Ionospheric electron density is sensed as well. The methods all share the key properties of self-calibration, high accuracy and vertical resolution, global coverage, and (if using radio signals) all-weather capability. Occultation data are thus of high value in a wide range of fields including climate monitoring and research, atmospheric physics and chemistry, operational meteorology, and other fields such as space weather and planetary science. This wide area of variants and uses of the occultation method has led to a diversi­ fication of the occultation-related scientific community into a...

  20. Upper tropospheric and lower stratospheric ENSO signal derived from GPS radio occultation temperature

    Science.gov (United States)

    Scherllin-Pirscher, B.; Deser, C.; Ho, S.-P.; Chou, C.; Randel, W.; Kuo, Y.-W.

    2012-04-01

    We use radio occultation (RO) temperature data from CHAMP, GRACE, and Formosat-3/COSMIC (F3C) to detect the El Niño-Southern Oscillation (ENSO) signal in the troposphere and lower stratosphere. Merging data of all satellites, we calculate monthly mean climatologies with a horizontal resolution of 5° latitude and 5° longitude and a vertical spacing of 100 m from the surface up to 20 km. A sufficient number of profiles (>40000 profiles per month) is available since August 2006, when F3C measurements became available. The investigation of temperature anomalies (anomalies are obtained from subtracting the mean annual cycle) in the equatorial region up to 16 km yields a natural split into zonal-mean and eddy (deviations from the zonal-mean) ENSO components. EOF1 is dominated by the zonally-symmetric component where positive sea-surface temperature anomalies come along with warm tropospheric temperatures. It explains almost 70 % of total variance. The corresponding PC1 is highly correlated with the Nino 3.4 index (correlation equals 0.85 at a lag of 3 months). EOF2, which is dominated by the eddy ENSO signal, explains more than 7 % of total variance. PC2 is almost perfectly correlated with the Nino 3.4 index (correlation equals 0.95 at a lag of 0 months). Due to these findings we separate data into zonal-mean and eddy temperature fields and apply PCA and multiple linear regression analysis separately to both fields. Taking advantage of the high vertical resolution of RO data, we show that the node of the positive and negative zonal-mean ENSO signal occurs around the tropopause. Relative to the surface ENSO signal, the atmospheric zonal-mean signal is lagged by 3 months. At low latitudes equatorwards of about 30°, the eddy ENSO signal is characterized by an east-west dipole centered slightly westward to the date line. The vertical node to a reversed east-west dipole occurs at approximately 14.5 km altitude, which is well below the tropopause. At tropospheric mid

  1. Zonal Flows and Turbulence in Fluids and Plasmas

    CERN Document Server

    Parker, Jeffrey B

    2015-01-01

    In geophysical and plasma contexts, zonal flows are well known to arise out of turbulence. We elucidate the transition from statistically homogeneous turbulence without zonal flows to statistically inhomogeneous turbulence with steady zonal flows. Starting from the Hasegawa--Mima equation, we employ both the quasilinear approximation and a statistical average, which retains a great deal of the qualitative behavior of the full system. Within the resulting framework known as CE2, we extend recent understanding of the symmetry-breaking `zonostrophic instability'. Zonostrophic instability can be understood in a very general way as the instability of some turbulent background spectrum to a zonally symmetric coherent mode. As a special case, the background spectrum can consist of only a single mode. We find that in this case the dispersion relation of zonostrophic instability from the CE2 formalism reduces exactly to that of the 4-mode truncation of generalized modulational instability. We then show that zonal flow...

  2. The vertical and spatial structure of ENSO in the upper troposphere and lower stratosphere from GPS radio occultation measurements

    Science.gov (United States)

    Scherllin-Pirscher, B.; Deser, C.; Ho, S.-P.; Chou, C.; Randel, W.; Kuo, Y.-H.

    2012-10-01

    The vertical and spatial structure of the atmospheric El Niño-Southern Oscillation (ENSO) signal is investigated using radio occultation (RO) data from August 2006 to December 2010. Due to their high vertical resolution and global coverage, RO data are well suited to describe the full 3-dimensional ENSO structure in the troposphere and lower stratosphere. We find that interannual temperature anomalies in the equatorial region show a natural decomposition into zonal-mean and eddy (deviations from the zonal-mean) components that are both related to ENSO. Consistent with previous studies, we find that during the warm phase of ENSO, zonal-mean temperatures increase in the tropical troposphere and decrease in the tropical stratosphere. Maximum warming occurs above 8 km, and the transition between warming and cooling occurs near the tropopause. This zonal-mean response lags sea surface temperature anomalies in the eastern equatorial Pacific by 3 months. The atmospheric eddy component, in contrast, responds rapidly (within 1 month) to ENSO forcing. This signal features a low-latitude dipole between the Indian and Pacific Oceans, with off-equatorial maxima centered around 20° to 30° latitude in both hemispheres. The eddy response pattern attains maximum amplitude in the upper troposphere near 11 km and (with opposite polarity) in a shallow layer near the tropopause at approximately 17 km. The eddy ENSO signal tends to be out-of-phase between low and middle latitudes in both the troposphere and lower stratosphere.

  3. Early detection of occult atrial fibrillation and stroke prevention.

    Science.gov (United States)

    Keach, Joseph Walker; Bradley, Steven M; Turakhia, Mintu P; Maddox, Thomas M

    2015-07-01

    Atrial fibrillation (AF) is a very common arrhythmia and significantly increases stroke risk. This risk can be mitigated with oral anticoagulation, but AF is often asymptomatic, or occult, preventing timely detection and treatment. Accordingly, occult AF may cause stroke before it is clinically diagnosed. Currently, guidelines for the early detection and treatment of occult AF are limited. This review addresses recent advancements in occult AF detection methods, identification of populations at high risk for occult AF, the treatment of occult AF with oral anticoagulation, as well as ongoing trials that may answer critically important questions regarding occult AF screening.

  4. Sociology of religion and the occult revival

    Directory of Open Access Journals (Sweden)

    Lennart Ejerfeldt

    1975-01-01

    Full Text Available The "new" that makes the cults of the occult revival to "new religions" of the Western world, is their recently increased social significance. Historically most of modern occultism is anything but new. From the research and theorizing about the occult revival we have picked up some main themes. The first is the social diffusion of the new occultism. In this field, we find some studies of superstition, especially astrology. These illuminate the differences in social connotation between the consumers of superstition and the followers of institutional religion. Secondly the study of the occult revival has made valuable contributions to the conceptualizing of "cult" and the cultic phenomenon. Thirdly, we will look upon the connection between the occult revival and the counter-culture. The problem of the rise of cults as a symptom of socio-cultural change will be briefly discussed with reference to Bell's thesis of "the disjuntion of culture and social structure". Lastly, we proffer some reflections on the occult revival and the new spiritual trends in the churches, which so sharply contrast with the theology and churchmanship of the sixties.

  5. Persistent occult hepatitis B virus infection: Experimental findings and clinical implications

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Hepatitis B virus (HBV) is a highly pathogenic virus that causes chronic liver diseases in millions of people globally. In addition to a symptomatic, serologically evident infection, occult persistent HBV carriage has been identified since nucleic acid amplification assays of enhanced sensitivity became introduced for detection of hepadnaviral genomes and their replicative intermediates. Current evidence indicates that occult HBV infection is a common and long-term consequence of resolution of acute hepatitis B. This form of residual infection is termed as secondary occult infection (SOI).The data from the woodchuck model of HBV infection indicate that exposure to small amounts of hepadnavirus can also cause primary occult infection (POI) where virus genome, but no serological makers of exposure to virus, are detectable, and the liver may not be involved.However, virus replicates at low levels in the lymphatic system in both these forms. We briefly summarize the current understanding of the nature and characteristics of occult hepadnaviral persistence as well as of its documented and expected pathological consequences.

  6. Outcome of Concurrent Occult Hemothorax and Pneumothorax in Trauma Patients Who Required Assisted Ventilation

    Science.gov (United States)

    Mahmood, Ismail; Tawfeek, Zainab; El-Menyar, Ayman; Zarour, Ahmad; Afifi, Ibrahim; Kumar, Suresh; Latifi, Rifat; Al-Thani, Hassan

    2015-01-01

    Background. The management and outcomes of occult hemopneumothorax in blunt trauma patients who required mechanical ventilation are not well studied. We aimed to study patients with occult hemopneumothorax on mechanical ventilation who could be carefully managed without tube thoracostomy. Methods. Chest trauma patients with occult hemopneumothorax who were on mechanical ventilation were prospectively evaluated. The presence of hemopneumothorax was confirmed by CT scanning. Hospital length of stay, complications, and outcome were recorded. Results. A total of 56 chest trauma patients with occult hemopneumothorax who were on ventilatory support were included with a mean age of 36 ± 13 years. Hemopneumothorax was managed conservatively in 72% cases and 28% underwent tube thoracostomy as indicated. 29% of patients developed pneumonia, 16% had Acute Respiratory Distress Syndrome (ARDS), and 7% died. Thickness of hemothorax, duration of mechanical ventilation, and development of ARDS were significantly associated with tube thoracostomy in comparison to no-chest tube group. Conclusions. The majority of occult hemopneumothorax can be carefully managed without tube thoracostomy in patients who required positive pressure ventilation. Tube thoracotomy could be restricted to those who had evidence of increase in the size of the hemothorax or pneumothorax on follow-up chest radiographs or developed respiratory compromise. PMID:25785199

  7. Future Nanosatellite Constellation for Radio Occultation Measurements

    Science.gov (United States)

    Fallet, C.; Mahfouf, J. F.; Hauchechrne, A.; Mathieu, R.; Martin, T.; Capet, N.; Mandea, M.

    2016-08-01

    The future nanosatellite constellation for radio occultation measurements aims to provide 10000 occultations per day (horizon 2020). The radio occultation technique based on the refraction of an electromagnetic signal between a GNSS satellite (Global Navigation Satellite System) and a receiver satellite located o a low orbit provides a way to observe the Earth's atmosphere, especially its temperature, pressure and water vapor, but also the ionosphere. This technique is now considered a mature concept, the benefits clearly recognized by the communities of weather prediction, climatology and space weather. Activities are underway at CNES to define a low cost system and instrumental concept to satisfy the specifications of the different communities.

  8. The Approach to Occult Gastrointestinal Bleed.

    Science.gov (United States)

    Naut, Edgar R

    2016-09-01

    Occult gastrointestinal bleeding is not visible and may present with a positive fecal occult blood test or iron deficiency anemia. Obscure bleeding can be overt or occult, with no source identified despite an appropriate diagnostic workup. A stepwise approach to this evaluation after negative upper and lower endoscopy has been shown to be cost effective. This includes repeat endoscopies if warranted, followed by video capsule endoscopy (VCE) if no obstruction is present. If the VCE is positive then specific endoscopic intervention may be possible. If negative, patients may undergo either repeat testing or watchful waiting with iron supplements. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. The Lunar Occultation Observer (LOCO) mission concept

    Science.gov (United States)

    Miller, Richard S.

    2007-09-01

    The hard X-ray sky has tremendous potential for future discoveries and is one of the last electromagnetic regimes without a sensitive all-sky survey. A new approach to such a survey is to utilize the Moon as an occulting disk. The Lunar Occultation Observer (LOCO) mission concept, based on this Lunar Occultation Technique (LOT) and incorporating advanced inorganic scintillators as a detection medium, represents a sensitive and cost effective option for NASA's Beyond Einstein Black Hole Finder Probe or a future Explorer-class mission. We present the motivating factors for the LOT, outline developmental details and simulation results, as well as give preliminary estimates for source detection sensitivity.

  10. The occultation of Arcturus in the Vatican

    CERN Document Server

    Sigismondi, Costantino

    2013-01-01

    The dome of Saint Peter's Basilica plays the role of the Moon during a stellar occultation and Arcturus is the target star. This occultation-like phenomenon is useful for introducing to occultation astronomy a class of student up to university level. It can be organized very easily at the convenience of the audience. Techical and didactical aspects are discussed; the video is available at http://www.youtube.com/watch?v=hIfsj7t-u-c and has been realized with an ordinary camcorder.

  11. Phase-Occultation Nulling Coronagraphy

    CERN Document Server

    Lyon, Richard G; Clampin, Mark; Petrone, Peter

    2015-01-01

    The search for life via characterization of earth-like planets in the habitable zone is one of the key scientific objectives in Astronomy. We describe a new phase-occulting (PO) interferometric nulling coronagraphy (NC) approach. The PO-NC approach employs beamwalk and freeform optical surfaces internal to the interferometer cavity to introduce a radially dependent plate scale difference between each interferometer arm (optical path) that nulls the central star at high contrast while transmitting the off-axis field. The design is readily implemented on segmented-mirror telescope architectures, utilizing a single nulling interferometer to achieve high throughput, a small inner working angle (IWA), sixth-order or higher starlight suppression, and full off-axis discovery space, a combination of features that other coronagraph designs generally must trade. Unlike previous NC approaches, the PO-NC approach does not require pupil shearing; this increases throughput and renders it less sensitive to on-axis common-mo...

  12. The Zonal Structure of the Hadley Circulation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A discussion of the mass transport of the Hadley circulation is presented, with regard to its longitudinal structure. Data from the NCEP/NCAR reanalysis data set for the period 1948-2005 is examined,focusing on the solsticial seasons of June-August and December-February. Quantitative estimates have been extracted from the data to observe connections between the zonal mean of the upper tropospheric north/south mass transports and their relationship to the driving factor of tropical precipitation (implying latent heat release) and subsidence in the subtropical high pressure belts. The longitudinal structure of this flow is then examined with regard to these three main variables. The poleward upper tropospheric transport has four (JJA) or three (DJF) main branches, which link regions of major precipitation with corresponding regions of large subsidence, and one (June, July, August) or two (December, January, February) reverse branches. This structure has remained stable over the past sixty years. Although the total upper tropospheric transport in each season is less than the total sinking transport in the target subtropical high pressure belt, this does not apply to the individual branches, the balance being made up by the upper tropospheric reverse transports. An analysis of correlations between all of these various components shows, however, that the complete picture is more complex, with some precipitation regions being linked to subsidence regions outside their own branch.

  13. Bounded relative motion under zonal harmonics perturbations

    Science.gov (United States)

    Baresi, Nicola; Scheeres, Daniel J.

    2017-04-01

    The problem of finding natural bounded relative trajectories between the different units of a distributed space system is of great interest to the astrodynamics community. This is because most popular initialization methods still fail to establish long-term bounded relative motion when gravitational perturbations are involved. Recent numerical searches based on dynamical systems theory and ergodic maps have demonstrated that bounded relative trajectories not only exist but may extend up to hundreds of kilometers, i.e., well beyond the reach of currently available techniques. To remedy this, we introduce a novel approach that relies on neither linearized equations nor mean-to-osculating orbit element mappings. The proposed algorithm applies to rotationally symmetric bodies and is based on a numerical method for computing quasi-periodic invariant tori via stroboscopic maps, including extra constraints to fix the average of the nodal period and RAAN drift between two consecutive equatorial plane crossings of the quasi-periodic solutions. In this way, bounded relative trajectories of arbitrary size can be found with great accuracy as long as these are allowed by the natural dynamics and the physical constraints of the system (e.g., the surface of the gravitational attractor). This holds under any number of zonal harmonics perturbations and for arbitrary time intervals as demonstrated by numerical simulations about an Earth-like planet and the highly oblate primary of the binary asteroid (66391) 1999 KW4.

  14. McDonald's and the Occult.

    Science.gov (United States)

    Singer, Barry

    1979-01-01

    Discusses "occult" and "paranormal" literature which is often mistaken for nonfiction. Suggests that most publishers are unwilling to publish scientific perspectives on the paranormal because such writings would be unmarketable. Journal availability: see SO 507 190. (KC)

  15. Radio occultation measurements of the lunar ionosphere.

    Science.gov (United States)

    Pluchino, S.; Schillirò, F.; Salerno, E.; Pupillo, G.; Maccaferri, G.; Cassaro, P.

    Radio occultation measurements by using interplanetary probes is a well known technique to obtain information on planetary atmospheres. To further understand the morphology of the lunar ionosphere we performed radio occultation experiments by using the radio sounding technique. This method mainly consists in the analisys of the effects produced on the radio wave transmitted from the spacecraft to the Earth when it crosses the atmosphere. The wave amplitude and phase undergo modifications that are correlated to the physical parameters - i.e. electron density - of the crossed medium. The first data set was obtained during the lunar occultations of the European probe SMART-1 shortly before impacting the lunar soil on September 3rd, 2006. During this experiment several radio occultation measurements of the signal transmitted by the spacecraft were performed in S and X band by using the 32 meters radiotelescopes (at Medicina and Noto) of the Istituto di Radioastronomia - Istituto Nazionale di Astrofisica. Further experiments were performed during lunar occultations of Saturn and Venus. On May 22nd and June 18th 2007 the Cassini spacecraft, orbiting Saturn, and the Venus Express spacecraft, orbiting Venus, respectively were occulted by the Moon. The variation of the Total Electron Content (TEC) measured by our instruments (˜ 1013 el/m2) on this occasion is in agreement with values of the electron number density acquired by in situ measuments of the US Apollo missions and the USSR Luna 19 and 22 probes.

  16. Method of Modeling and Simulation of Shaped External Occulters

    Science.gov (United States)

    Lyon, Richard G. (Inventor); Clampin, Mark (Inventor); Petrone, Peter, III (Inventor)

    2016-01-01

    The present invention relates to modeling an external occulter including: providing at least one processor executing program code to implement a simulation system, the program code including: providing an external occulter having a plurality of petals, the occulter being coupled to a telescope; and propagating light from the occulter to a telescope aperture of the telescope by scalar Fresnel propagation, by: obtaining an incident field strength at a predetermined wavelength at an occulter surface; obtaining a field propagation from the occulter to the telescope aperture using a Fresnel integral; modeling a celestial object at differing field angles by shifting a location of a shadow cast by the occulter on the telescope aperture; calculating an intensity of the occulter shadow on the telescope aperture; and applying a telescope aperture mask to a field of the occulter shadow, and propagating the light to a focal plane of the telescope via FFT techniques.

  17. Update on occult hepatitis B virus infection.

    Science.gov (United States)

    Makvandi, Manoochehr

    2016-10-21

    The event of mutations in the surface antigen gene of hepatitis B virus (HBV) results in undetectable hepatitis B surface antigen with positive/negative anti-hepatitis B core (anti-HBc) antibody status in serum and this phenomenon is named occult hepatitis B infection (OBI). The presence of anti-HBc antibody in serum is an important key for OBI tracking, although about 20% of OBI cases are negative for anti-HBc antibody. The diagnosis of OBI is mainly based on polymerase chain reaction (PCR) and real-time PCR assays. However, real-time PCR is a more reliable method than PCR. OBI is a great issue for the public health problem and a challenge for the clinical entity worldwide. The persistence of OBI may lead to the development of cirrhosis and hepatocellular carcinoma. With regard to OBI complications, the screening of HBV DNA by the highly sensitive molecular means should be implemented for: (1) patients with a previous history of chronic or acute HBV infection; (2) patients co-infected with hepatitis C virus/human immunodeficiency virus; (3) patients undergoing chemotherapy or anti-CD20 therapy; (4) recipients of organ transplant; (5) blood donors; (6) organ transplant donors; (7) thalassemia and hemophilia patients; (8) health care workers; (9) patients with liver related disease (cryptogenic); (10) hemodialysis patients; (11) patients undergoing lamivudine or interferon therapy; and (12) children in time of HBV vaccination especially in highly endemic areas of HBV. Active HBV vaccination should be implemented for the close relatives of patients who are negative for OBI markers. Thus, the goal of this review is to evaluate the rate of OBI with a focus on status of high risk groups in different regions of the world.

  18. Update on occult hepatitis B virus infection

    Science.gov (United States)

    Makvandi, Manoochehr

    2016-01-01

    The event of mutations in the surface antigen gene of hepatitis B virus (HBV) results in undetectable hepatitis B surface antigen with positive/negative anti-hepatitis B core (anti-HBc) antibody status in serum and this phenomenon is named occult hepatitis B infection (OBI). The presence of anti-HBc antibody in serum is an important key for OBI tracking, although about 20% of OBI cases are negative for anti-HBc antibody. The diagnosis of OBI is mainly based on polymerase chain reaction (PCR) and real-time PCR assays. However, real-time PCR is a more reliable method than PCR. OBI is a great issue for the public health problem and a challenge for the clinical entity worldwide. The persistence of OBI may lead to the development of cirrhosis and hepatocellular carcinoma. With regard to OBI complications, the screening of HBV DNA by the highly sensitive molecular means should be implemented for: (1) patients with a previous history of chronic or acute HBV infection; (2) patients co-infected with hepatitis C virus/human immunodeficiency virus; (3) patients undergoing chemotherapy or anti-CD20 therapy; (4) recipients of organ transplant; (5) blood donors; (6) organ transplant donors; (7) thalassemia and hemophilia patients; (8) health care workers; (9) patients with liver related disease (cryptogenic); (10) hemodialysis patients; (11) patients undergoing lamivudine or interferon therapy; and (12) children in time of HBV vaccination especially in highly endemic areas of HBV. Active HBV vaccination should be implemented for the close relatives of patients who are negative for OBI markers. Thus, the goal of this review is to evaluate the rate of OBI with a focus on status of high risk groups in different regions of the world. PMID:27818588

  19. Role of stable modes in zonal flow regulated ITG turbulence

    Science.gov (United States)

    Makwana, Kirit; Terry, Paul; Hatch, David; Pueschel, M. J.

    2012-10-01

    Stable modes are studied in zonal flow regulated ITG turbulence using the gyrokinetic code GENE. Proper orthogonal decomposition (POD) modes are employed to investigate the eigenmode space of the distribution function. Both the unstable and stable POD modes show strong nonlinear energy transfer via three wave interactions that include zonal modes. The zonal mode itself absorbs a small fraction of the energy injected by the unstable mode. The remaining energy is deposited in the stable modes of non-zonal wavenumbers that are involved in the three wave coupling. These stable modes lie mostly within the wavenumber range of the instability. This indicates that zonal flows mediate energy transfer from unstable to stable modes, leading to saturation. The amplitude attenuation rate (AAR) of POD modes shows an equipartition across a large range of stable modes. This rate is balanced by three wave correlations of the POD modes and their time dependent amplitudes. These correlations are large if they involve zonal modes and they also show an equipartition for higher mode numbers. A similar analysis using linear eigenmodes also shows rough equipartition among the linear modes. Thus, AAR provides a handle to collectively describe the multitude of stable modes in a gyrokinetic simulation.

  20. Defining occult injuries of the distal forearm and wrist in children.

    Science.gov (United States)

    Elvey, Michael; Patel, S; Avisar, Erez; White, W J; Sorene, E

    2016-06-01

    The nonspecific terms "wrist sprain" and "suspected occult bony injury" are frequently documented as diagnoses in occult paediatric wrist injuries. To date, however, no one has accurately defined their true underlying pathology. The primary objective of this study was to identify the true pathoanatomy of occult acute paediatric wrist injuries. Our secondary objective was to compare our findings with existing adult data in order to determine any population differences that might be clinically relevant. We performed a single-centre retrospective case series evaluating MRI findings in acute paediatric wrist injuries presenting to the hand injury unit between 2011 and 2014. All patients underwent standardised radiographs of the wrist and, where clinically indicated, of the scaphoid. Where no bony anomaly was identified, MRI scanning was offered. Cohen's kappa coefficient was used to calculate the agreement between clinical and MRI diagnosis. 57 patients met the final inclusion criteria. Occult fractures and bony contusions comprised the majority of the pathologies, at 36.5 and 35.0 %, respectively. There were no cases of isolated soft-tissue injury. MRI effected management change in 35.1 % of cases. Paediatric wrists demonstrated differences in injury pattern and distribution when compared to an adult population. This study defines for the first time the true pathology of occult paediatric wrist injuries. The current definition of a wrist sprain was not applicable to a single case and therefore appears to be inappropriate for use in the paediatric population. A precise knowledge of the likely pathology facilitates accurate information delivery whilst reducing parental uncertainty and treatment variation.

  1. The Big Occulting Steerable Satellite (BOSS)

    CERN Document Server

    Copi, C J; Copi, Craig J.; Starkman, Glenn D.

    1999-01-01

    Natural (such as lunar) occultations have long been used to study sources on small angular scales, while coronographs have been used to study high contrast sources. We propose launching the Big Occulting Steerable Satellite (BOSS), a large steerable occulting satellite to combine both of these techniques. BOSS will have several advantages over standard occulting bodies. BOSS would block all but about 4e-5 of the light at 1 micron in the region of interest around the star for planet detections. Because the occultation occurs outside the telescope, scattering inside the telescope does not degrade this performance. BOSS could be combined with a space telescope at the Earth-Sun L2 point to yield very long integration times, in excess of 3000 seconds. If placed in Earth orbit, integration times of 160--1600 seconds can be achieved from most major telescope sites for objects in over 90% of the sky. Applications for BOSS include direct imaging of planets around nearby stars. Planets separated by as little as 0.1--0....

  2. [Progress in research of occult hepatitis B virus infection].

    Science.gov (United States)

    Huang, X Y; Shi, Q F; Huang, T

    2017-05-10

    Occult hepatitis B virus infection is a worldwide public health problem, which seriously affects the clinical diagnosis of hepatitis B and threatens the safety of blood transfusion. The concept of occult hepatitis B virus infection, the pathogenesis of occult hepatitis B virus infection, the prevalence of occult hepatitis B virus infection in different groups, including healthy population and different patients, and the possibility of transmission were summarized. The prevalence of occult hepatitis B virus infection was found in healthy population and different patients, and there is possibility of occult hepatitis B virus infection to be transmitted through blood transfusion. The paper provides a comprehensive introduction of the pathogenesis and prevalence of occult hepatitis B virus infection. More attention should be paid to occult hepatitis B virus infection.

  3. [Occult hepatitis B virus infection and hepatocellular carcinoma].

    Science.gov (United States)

    Lee, Jong Joon; Kwon, Oh Sang

    2013-09-01

    Many studies have suggested that occult HBV infection has a substantial clinical relevance to hepatocellular carcinoma (HCC). Occult HBV infection is an important risk factor for the development of cirrhosis and HCC in patients without HBsAg. As a matter of fact, occult HBV infection is one of the most common causes of crytogenic HCC in endemic areas of HBV. However, there still are controversial issues about the association between occult HBV infection and HCC according to the underlying liver disease. In alcoholic cirrhosis, occult HBV infection may exert synergistic effect on the development of HCC. However, there is insufficient evidence to relate occult HBV infection to hepatocarcinogenesis in non-alcoholic fatty liver disease. In cryptogenic HCC, occult HBV infection may play a direct role in the development of HCC. In order to elucidate the assocciation between occult HBV infection and HCC, underlying liver disease must be specified and larger number of cases must be included in future studies.

  4. Zonal disintegration phenomenon in rock mass surrounding deep tunnels

    Institute of Scientific and Technical Information of China (English)

    WU Hao; FANG Qin; GUO Zhi-kun

    2008-01-01

    Zonal disintegration is a typical static phenomenon of deep rock masses. It has been defined as alternating regions of fractured and relatively intact rock mass that appear around or in front of the working stope during excavation of a deep tunnel. Zonal disintegration phenomenon was successfully demonstrated in the laboratory with 3D tests on analogous gypsum models, two circular cracked zones were observed in the test. The linear Mohr-Coulomb yield criterion was used with a constitutive model that showed linear softening and ideal residual plastic to analyze the elasto-plastic field of the enclosing rock mass around a deep tunnel. The results show that tunneling causes a maximum stress zone to appear between an elastic and plastic zone in the surrounding rock. The zonal disintegration phenomenon is analyzed by considering the stress-strain state of the rock mass in the vicinity of the maximum stress zone. Creep instability failure of the rock due to the development of the plastic zone, and transfer of the maximum stress zone into the rock mass, are the cause of zonal disintegration. An analytical criterion for the critical depth at which zonal disintegration can occur is derived. This depth depends mainly on the character and stress concentration coefficient of the rock mass.

  5. Characteristics of tropopause parameters as observed with GPS radio occultation

    Directory of Open Access Journals (Sweden)

    T. Rieckh

    2014-11-01

    Full Text Available Characteristics of the lapse rate tropopause are analyzed globally for tropopause altitude and temperature using global positioning system (GPS radio occultation (RO data from late 2001 to the end of 2013. RO profiles feature high vertical resolution and excellent quality in the upper troposphere and lower stratosphere, which are key factors for tropopause determination, including multiple ones. RO data provide measurements globally and allow examination of both temporal and spatial tropopause characteristics based entirely on observational measurements. To investigate latitudinal and longitudinal tropopause characteristics, the mean annual cycle, and inter-annual variability, we use tropopauses from individual profiles as well as their statistical measures for zonal bands and 5° × 10° bins. The latitudinal structure of first tropopauses shows the well-known distribution with high (cold tropical tropopauses and low (warm extra-tropical tropopauses. In the transition zones (20 to 40° N/S, individual profiles reveal varying tropopause altitudes from less than 7 km to more than 17 km due to variability in the subtropical tropopause break. In this region, we also find multiple tropopauses throughout the year. Longitudinal variability is strongest at northern hemispheric mid latitudes and in the Asian monsoon region. The mean annual cycle features changes in amplitude and phase, depending on latitude. This is caused by different underlying physical processes (such as the Brewer–Dobson circulation – BDC and atmospheric dynamics (such as the strong polar vortex in the southern hemispheric winter. Inter-annual anomalies of tropopause parameters show signatures of El Niño–Southern Oscillation (ENSO, the quasi–biennial oscillation (QBO, and the varying strength of the polar vortex, including sudden stratospheric warming (SSW events. These results are in good agreement with previous studies and underpin the high utility of the entire RO record

  6. The Radio Occultation Processing Package ROPP

    Directory of Open Access Journals (Sweden)

    I. D. Culverwell

    2015-01-01

    Full Text Available This paper describes the Radio Occultation Processing Package, ROPP, a product of the EUMETSAT Radio Occultation Meteorology Satellite Application Facility (ROM SAF developed by a large number of scientists over many years. A brief review of the concepts, functionality and structure of ROPP is followed by more detailed descriptions of its key capabilities. Example results from a full chain of processing using some of the ROPP tools are presented. Some current and prospective uses of ROPP are given. Instructions on how to access the code and its supporting documentation are provided.

  7. Impact of zonal flows on edge pedestal collapse

    Science.gov (United States)

    Jhang, Hogun; Kaang, Helen H.; Kim, S. S.; Rhee, T.; Singh, R.; Hahm, T. S.

    2017-02-01

    We perform a computational study of the role of zonal flows in edge pedestal collapse on the basis of a nonlinear three-field reduced magnetohydrodynamic (MHD) model. A dramatic change of dynamics takes place when ideal ballooning modes are completely stabilized. Analyses show that a new instability is developed due to a strong excitation of zonal vorticity, resulting in a series of secondary crashes. The presence of subsidiary bursts after a main crash increases the effective crash time and energy loss. These simulation results resemble the behavior of compound edge localized modes (ELMs). Analyses in this paper indicate that a complete understanding of ELM crash dynamics requires the self-consistent inclusion of nonlinear zonal flows-MHD interaction and transport physics.

  8. Inertial wave and zonal flow in librating spherical shells

    CERN Document Server

    Lin, Yufeng; Calkin, Michael A

    2014-01-01

    We numerically study the inertial waves and zonal flows in spherical shells driven by longitudinal libration, an oscillatory variation of rotation rate. Internal shear layers are generated due to breakdown of the Ekman boundary layer at critical latitudes. Our numerical results validate the scaling laws of internal shear layers predicted by previous studies. Mean zonal flows are driven by the non-linear interaction in the boundary layers. Non-linear interaction of inertial waves in the interior fluids has no significant contribution to the zonal flow. Multiple geostrophic shear layers are generated due to non-linearities in the boundary layers at critical latitudes and reflection points of internal shear layers. We also investigate the scaling laws of geostrophic shear layers and extrapolate the results to the planetary setting.

  9. Magnetic Field Generation and Zonal Flows in the Gas Giants

    Science.gov (United States)

    Duarte, L.; Wicht, J.; Gastine, T.

    2013-12-01

    The surface dynamics of Jupiter and Saturn is dominated by a banded system of fierce zonal winds. The depth of these winds remains unclear but they are thought to be confined to the very outer envelopes where hydrogen remains molecular and the electrical conductivity is negligible. The dynamo responsible for the dipole dominated magnetic fields of both Gas Giants, on the other hand, likely operates in the deeper interior where hydrogen assumes a metallic state. We present numerical simulations that attempt to model both the zonal winds and the interior dynamo action in an integrated approach. Using the anelastic version of the MHD code MagIC, we explore the effects of density stratification and radial electrical conductivity variations. The electrical conductivity is assumed to remain constant in the thicker inner metallic region and decays exponentially towards the outer boundary throughout the molecular envelope. Our results show that the combination of stronger density stratification (Δρ≈55) and a weaker conducting outer layer is essential for reconciling dipole dominated dynamo action and a fierce equatorial zonal jet. Previous simulations with homogeneous electrical conductivity show that both are mutually exclusive, with solutions either having strong zonal winds and multipolar magnetic fields or weak zonal winds and dipole dominated magnetic fields. The particular setup explored here allows the equatorial jet to remain confined to the weaker conducting region where is does not interfere with the deeper seated dynamo action. The equatorial jet can afford to remain geostrophic and reaches throughout the whole shell. This is not an option for the additional mid to higher latitude jets, however. In dipole dominated dynamo solutions, appropriate for the Gas Giants, zonal flows remain very faint in the deeper dynamo region but increase in amplitude in the weakly conducting outer layer in some of our simulations. This suggests that the mid to high latitude jets

  10. Characterization of zonal flow generation in weak electrostatic turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Negrea, M; Petrisor, I [Department of Physics, Association Euratom-MEdC, Romania, University of Craiova, 13 A.I. Cuza Street, 200585 Craiova (Romania); Weyssow, B [Physique Statistique-Plasmas, Association Euratom-Etat Belge, Universite Libre de Bruxelles, Campus Plaine, Bd. du Triomphe, 1050 Bruxelles (Belgium)], E-mail: mnegrea@yahoo.com

    2008-05-15

    The influence of the diamagnetic Kubo number, which is proportional to the diamagnetic drift velocity, on the zonal flow generation by an anisotropic stochastic electrostatic potential is considered from a semi-analytic point of view. The analysis is performed in the weak turbulence limit and as an analytical tool the decorrelation trajectory method is used. It is shown that the fragmentation of the drift wave structures (a signature of the zonal flow generation) is influenced not only by the anisotropy parameter and the electrostatic Kubo number as expected, but also by the diamagnetic Kubo number. Global Lagrangian averages of characteristic quantities are calculated and interpreted.

  11. Characteristics of the global thermal tropopause derived from multiple radio occultation measurements

    Science.gov (United States)

    Li, Wei; Yuan, Yun-bin; Chai, Yan-Ju; Liou, Yuei-An; Ou, Ji-kun; Zhong, Shi-ming

    2017-03-01

    Thermal tropopause represents the region of the atmosphere where the environmental lapse rate changes from tropospheric positive to stratospheric negative. It also defines the altitude of the atmosphere beneath which significant weather perturbations occur except occasional overshooting thunderstorms in the tropical regions. Accordingly, how the temporal and spatial variability of thermal tropopause behaves is of great concern in atmospheric research and, hence, investigated in this study by using radio occultation (RO) observations obtained from seven space missions during the period from May 2001 to April 2013 (with a total of 6,075,359 occultations). While RO observations have been demonstrated to provide precise measurements of temperature profiles of the atmosphere, their results are inter-compared before further use in our analysis, showing expected high-precision observations with mean differences < 0.06 K and standard deviations < 1.6 K in the upper troposphere and lower stratosphere. Given a rather large data set of multi- space-mission RO measurements taken globally, a very detailed description of spatial structure and variability of the tropopause is revealed, and monthly mean zonal mean tropopause parameters in each 2° latitude band from 90°S to 90°N can be obtained. Many interesting features of seasonal cycle, spatial distribution, interannual variation, and diurnal variation of the thermal tropopause are observed. For examples, except for the primary minimum in January, the equatorial tropopause temperature exhibits a secondary minimum in April, possibly caused by the strongly combined wave forcing from two hemispheres; During the boreal winter over the tropics, the distribution of tropopause temperature extrema do not totally coincide with the altitude extrema spatially, and the former has a better agreement with the locations of strong tropical convection systems; Notable zonal asymmetries in interannual characteristics are observed in both

  12. Statistical Methods for Detecting Stellar Occultations by Kuiper Belt Objects the Taiwanese-American Occultation Survey

    CERN Document Server

    Liang, C L; De Pater, I; Alcock, C B; Axelrod, T; Wang, A; Liang, Chyng-Lan; Rice, John A.; Pater, Imke de; Alcock, Charles; Axelrod, Tim; Wang, Andrew

    2002-01-01

    The Taiwanese-American Occultation Survey (TAOS) will detect objects in the Kuiper Belt, by measuring the rate of occultations of stars by these objects, using an array of three to four 50cm wide-field robotic telescopes. Thousands of stars will be monitored, resulting in hundreds of millions of photometric measurements per night. To optimize the success of TAOS, we have investigated various methods of gathering and processing the data and developed statistical methods for detecting occultations. In this paper we discuss these methods. The resulting estimated detection efficiencies will be used to guide the choice of various operational parameters determining the mode of actual observation when the telescopes come on line and begin routine observations. In particular we show how real-time detection algorithms may be constructed, taking advantage of having multiple telescopes. We also discuss a retrospective method for estimating the rate at which occultations occur.

  13. Controversies about occult hepatitis B virus infection

    Institute of Scientific and Technical Information of China (English)

    Ersan Ozaslan; Tugrul Purnak

    2009-01-01

    We read with great interest the paper written by Shi et al, reviewing the molecular characteristics and stages of chronic hepatitis B virus (HBV) infection. We think that some points in the definition of occult HBV infection (OBI) and their conclusion about the management of OBI may need further considerations.

  14. Occult spondyloarthritis in inflammatory bowel disease.

    Science.gov (United States)

    Bandinelli, Francesca; Manetti, Mirko; Ibba-Manneschi, Lidia

    2016-02-01

    Spondyloarthritis (SpA) is a frequent extra-intestinal manifestation in patients with inflammatory bowel disease (IBD), although its real diffusion is commonly considered underestimated. Abnormalities in the microbioma and genetic predisposition have been implicated in the link between bowel and joint inflammation. Otherwise, up to date, pathogenetic mechanisms are still largely unknown and the exact influence of the bowel activity on rheumatic manifestations is not clearly explained. Due to evidence-based results of clinical studies, the interest on clinically asymptomatic SpA in IBD patients increased in the last few years. Actually, occult enthesitis and sacroiliitis are discovered in high percentages of IBD patients by different imaging techniques, mainly enthesis ultrasound (US) and sacroiliac joint X-ray examinations. Several diagnostic approaches and biomarkers have been proposed in an attempt to correctly classify and diagnose clinically occult joint manifestations and to define clusters of risk for patient screening, although definitive results are still lacking. The correct recognition of occult SpA in IBD requires an integrated multidisciplinary approach in order to identify common diagnostic and therapeutic strategies. The use of inexpensive and rapid imaging techniques, such as US and X-ray, should be routinely included in daily clinical practice and trials to correctly evaluate occult SpA, thus preventing future disability and worsening of quality of life in IBD patients.

  15. Clinical Characteristics and Treatment for Patients with Occult Chronic hepatitis B

    Institute of Scientific and Technical Information of China (English)

    Qing-wei Gao; De-sheng Yuan

    2013-01-01

    Objective To observe the clinical manifestations and assess direct antiviral effect for patients with occult hepatitis B in China. Methods The study includes 15 patients with occult hepatitis B and their medical history, family history, ifrst-diagnosis time, conifrmed-diagnosis time, laboratory report, anti-viral therapy and outcomes were analyzed. Results The average age of the patients is 38.67-year old (6 males and 9 females), 2 with acute hepatitis B (2/15, 13.3%), 13 with no hepatitis history (13/15, 86.6%), 8 with family history (8/15, 53.3%), 6 with no family history (6/15, 40%), 1 with unknown family history (1/15, 6.6%). Eight patients were treated with entecavir (0.5 mg/day, taken orally), with effective results and steady conditions;3 patients were treated with lamivudine (0.1 g/day, taken orally), 2 of them were prescribed to take adefovir dipivoxil additionally due to drug-resistance, the other one was treated with lamivudine continuously without drug-resistance;4 cases refused anti-viral therapy. One patient’s condition remained steady, 1 patient died of cirrhosis with portal hypertension and liver failure 5 years after ifrst-diagnosis, 1 patient progressed to hepatocellular carcinoma and accepted surgery operation treatment 5 years after ifrst-diagnosis, the other 1 patient progressed to compensatory cirrhosis 2 years after ifrst-diagnosis and is steady from then, which indicates that occult chronic hepatitis B can progress to cirrhosis and hepatocellular carcinoma without therapy in time. Conclusions The clinical characteristics of 15 cases with occult chronic hepatitis B showed that these patients with short latency, younger age when being-struck, and light damage to liver function. The efifcacy and drug-resistance of nucleos(t)ide-analogue (entecavir, lamivudine, adefovir dipivoxil) in treatment of patients with occult chronic hepatitis B are similar to chronic hepatitis B.

  16. Prevalence of occult hepatitis B virus infection in hemodialysis patients in Isfahan, Iran

    Science.gov (United States)

    Kalantari, Hamid; Ferdowsi, Faezeh; Yaran, Majid

    2016-01-01

    Background: The absence of a detectable hepatitis B surface antigen (HBsAg) with or without hepatitis B core antibody (anti-HBc) or hepatitis B surface antibody (anti-HBs) in the presence of hepatitis B virus-DNA (HBV-DNA) is defined as occult HBV infection. This study was aimed to evaluate the prevalence of occult HBV infection in patients receiving hemodialysis (HD) in Isfahan, Iran. Materials and Methods: This cross sectional study was done on 400 patients without acute or chronic HBV infection with end-stage renal disease undergoing regular HD. Blood samples were collected prior to the HD session, and serological markers of viral hepatitis B included HBsAg, anti-HBs and anti-HBc were measured using standard third generation commercially available enzyme immunoassays kit, then samples of positive anti-HBc and negative anti-HBs were tested for HBV DNA using quantitative real-time polymerase chain reaction techniques. Data were analyzed by SPSS using t-test and Chi-square test. Results: The mean age of patients was 51.6 ± 11.2 years. Anti-HBc positive was observed in 32 (8%) of 400 studied patients with negative HBsAg. Of 32 patients with anti-HBc positive, 15 were males and 17 were females with mean age of 49.7 ± 12.6 years. Among 32 patients with anti-HBc positive, 10 patients were negative for anti-HBs. All of 10 patients were negative for HBV DNA. The prevalence of occult HBV infection was 0%. Conclusions: The prevalence of occult HBV infection in HBsAg negative patients undergoing HD was 0% and look to be among the lowest worldwide. So, occult HBV infection is not a significant health problem in HD patients in this region.

  17. Occult hepatitis B infection: an evolutionary scenario

    Directory of Open Access Journals (Sweden)

    Lukashov Vladimir V

    2008-12-01

    Full Text Available Abstract Background Occult or latent hepatitis B virus (HBV infection is defined as infection with detectable HBV DNA and undetectable surface antigen (HBsAg in patients' blood. The cause of an overt HBV infection becoming an occult one is unknown. To gain insight into the mechanism of the development of occult infection, we compared the full-length HBV genome from a blood donor carrying an occult infection (d4 with global genotype D genomes. Results The phylogenetic analysis of polymerase, core and X protein sequences did not distinguish d4 from other genotype D strains. Yet, d4 surface protein formed the evolutionary outgroup relative to all other genotype D strains. Its evolutionary branch was the only one where accumulation of substitutions suggests positive selection (dN/dS = 1.3787. Many of these substitutiions accumulated specifically in regions encoding the core/surface protein interface, as revealed in a 3D-modeled protein complex. We identified a novel RNA splicing event (deleting nucleotides 2986-202 that abolishes surface protein gene expression without affecting polymerase, core and X-protein related functions. Genotype D strains differ in their ability to perform this 2986-202 splicing. Strains prone to 2986-202 splicing constitute a separate clade in a phylogenetic tree of genotype D HBVs. A single substitution (G173T that is associated with clade membership alters the local RNA secondary structure and is proposed to affect splicing efficiency at the 202 acceptor site. Conclusion We propose an evolutionary scenario for occult HBV infection, in which 2986-202 splicing generates intracellular virus particles devoid of surface protein, which subsequently accumulates mutations due to relaxation of coding constraints. Such viruses are deficient of autonomous propagation and cannot leave the host cell until it is lysed.

  18. The Big Occulting Steerable Satellite (BOSS)

    Energy Technology Data Exchange (ETDEWEB)

    Copi, Craig J.; Starkman, Glenn D.

    2000-03-20

    Natural (such as lunar) occultations have long been used to study sources on small angular scales, while coronographs have been used to study high-contrast sources. We describe here the properties of the Big Occulting Steerable Satellite (BOSS), a large steerable occulting satellite to combine both of these techniques. BOSS will have several advantages over standard occulting bodies. BOSS would block all but about 4x10{sup -5} of the light at 1 {mu}m in the region of interest around the star for planet detections (with even better blocking possible using new film surface etching techniques). Because the occultation occurs outside the telescope, scattering inside the telescope does not degrade this performance. BOSS could be combined with a space telescope at the Earth-Sun L2 point to yield very long integration times, in excess of 3000 s. If placed in Earth orbit, integration times of 160-1600 s can be achieved from most major telescope sites for objects in over 90% of the sky. Applications for BOSS include direct imaging of planets around nearby stars. Planets separated by as little as 0.1''-0.25'' from the star they orbit could be seen down to a relative intensity as little as 1x10{sup -9} around a magnitude 8 (or brighter) star. Other applications include ultra-high-resolution imaging of compound sources, such as microlensed stars and quasars, down to a resolution as little as 0.1 mas. (c) 2000 The American Astronomical Society.

  19. Cassini Radio Occultation by Enceladus Plume

    Science.gov (United States)

    Kliore, A.; Armstrong, J.; Flasar, F.; French, R.; Marouf, E.; Nagy, A.; Rappaport, N.; McGhee, C.; Schinder, P.; Anabtawi, A.; Asmar, S.; Barbinis, E.; Fleischman, D.; Goltz, G.; Aguilar, R.; Rochblatt, D.

    2006-12-01

    A fortuitous Cassini radio occultation by Enceladus plume occurs on September 15, 2006. The occultation track (the spacecraft trajectory in the plane of the sky as viewed from the Earth) has been designed to pass behind the plume (to pass above the south polar region of Enceladus) in a roughly symmetrical geometry centered on a minimum altitude above the surface of about 20 km. The minimum altitude was selected primarily to ensure probing much of the plume with good confidence given the uncertainty in the spacecraft trajectory. Three nearly-pure sinusoidal signals of 0.94, 3.6, and 13 cm-wavelength (Ka-, X-, and S-band, respectively) are simultaneously transmitted from Cassini and are monitored at two 34-m Earth receiving stations of the Deep Space Network (DSN) in Madrid, Spain (DSS-55 and DSS-65). The occultation of the visible plume is extremely fast, lasting less than about two minutes. The actual observation time extends over a much longer time interval, however, to provide a good reference baseline for potential detection of signal perturbations introduced by the tenuous neutral and ionized plume environment. Given the likely very small fraction of optical depth due to neutral particles of sizes larger than about 1 mm, detectable changes in signal intensity is perhaps unlikely. Detection of plume plasma along the radio path as perturbations in the signals frequency/phase is more likely and the magnitude will depend on the electron columnar density probed. The occultation time occurs not far from solar conjunction time (Sun-Earth-probe angle of about 33 degrees), causing phase scintillations due to the solar wind to be the primary limiting noise source. We estimate a delectability limit of about 1 to 3E16 electrons per square meter columnar density assuming about 100 seconds integration time. Potential measurement of the profile of electron columnar density along the occultation track is an exciting prospect at this time.

  20. Generation of zonal flows in rotating fluids and magnetized plasmas

    DEFF Research Database (Denmark)

    Juul Rasmussen, J.; Garcia, O.E.; Naulin, V.

    2006-01-01

    contribution the generation of zonal flows will be illustrated in a simple fluid experiment performed in a rotating container with radial symmetric bottom topography. An effective mixing that homogenizes the potential vorticity in the fluid layer will lead to the replacement of the high-potential vorticity...

  1. Can zonally symmetric inertial waves drive an oscillating mean flow?

    Science.gov (United States)

    Seelig, Torsten; Harlander, Uwe

    2016-04-01

    In the presentation [5] zonal mean flow excitation by inertial waves is studied in analogy to mean flow excitation by gravity waves [3] that plays an important role for the quasi-biennial oscillation in the equatorial atmosphere. In geophysical flows that are stratified and rotating, pure gravity and inertial waves correspond to the two limiting cases: gravity waves neglect rotation, inertial waves neglect stratification. The former are more relevant for fluids like the atmosphere, where stratification is dominant, the latter for the deep oceans or planet cores, where rotation dominates. In the present study a hierarchy of simple analytical and numerical models of zonally symmetric inertial wave-mean flow interactions is considered and the results are compared with data from a laboratory experiment [4]. The main findings can be summarised as follows: (i) when the waves are decoupled from the mean flow they just drive a retrograde (eastward) zonal mean flow, independent of the sign of the meridional phase speed; (ii) when coupling is present and the zonal mean flow is assumed to be steady, the waves can drive vertically alternating jets, but still, in contrast to the gravity wave case, the structure is independent of the sign of the meridional phase speed; (iii) when coupling is present and time-dependent zonal mean flows are considered the waves can drive vertically and temporarily oscillating mean flows. The comparison with laboratory data from a rotating annulus experiment shows a qualitative agreement. It appears that the experiment captures the basic elements of the inertial wave mean flow coupling. The results might be relevant to understand how the Equatorial Deep Jets can be maintained against dissipation [1, 2], a process currently discussed controversially. [1] Greatbatch, R., Brandt, P., Claus, M., Didwischus, S., Fu, Y.: On the width of the equatorial deep jets. J. Phys. Oceanogr. 42, 1729-1740 (2012) [2] Muench, J.E., Kunze, E.: Internal wave

  2. Dynamic mechanism of interannual zonal displacements of the eastern edge of the western Pacific warm pool

    Institute of Scientific and Technical Information of China (English)

    齐庆华; 张启龙; 侯一筠

    2010-01-01

    The eastern edge of the western Pacific warm pool (WPWP) in the upper layer (shallower than 50m) exhibits significant zonal displacements on interannual scale. Employing an intermediate ocean model, the dynamic mechanism for the interannual zonal displacement of the WPWP eastern edge in the upper layer is investigated by diagnosing the dynamic impacts of zonal current anomalies induced by wind, waves (Kelvin and Rossby waves), and their boundary reflections. The interannual zonal displacements of the WPWP e...

  3. PV-θ view of the zonal mean state of the atmosphere

    NARCIS (Netherlands)

    van Delden, A.J.; Hinssen, Y.B.L.

    2012-01-01

    The relation between zonal mean potential vorticity (PV) in potential temperature (u) coordinates and the zonal mean zonal wind in January and in July is studied. PV-anomalies are defined with respect to a reference state that is at rest with respect to the rotating earth. Two important PV-anomalies

  4. [Chronic hepatitis and occult HCV infection].

    Science.gov (United States)

    Kowala-Piaskowska, Arleta; Mozer-Lisewska, Iwona; Pham, Tram N Q; Michalak, Tomasz I

    2010-01-01

    Hepatitis C virus (HCV) was discovered in 1989. HCV is a positive single-strand RNA. We all have thought, that HCV can replicate only in liver tissue, but now we know, that HCV can replicate in extrahepatic tissue as well. In about 48-86% of HCV infected patients, chronic hepatitis C (CHC) has been noticed and eventually, after tens of years, liver insufficiency, cirrhosis or hepatocellular carcinoma. The current recommended treatment for CHC is a combination of pegylated-interferon alpha and Ribavirin. Presently it is known, that HCV infection can persist as an occult infection. RNA HCV can be detected in patients after successful treatment for CHC or spontaneous elimination. Persistent HCV replication in hepatocytes or lymphoid cells would likely lead to continuous antigenic stimulation of the immune system. This prolonged replication may contribute to the immune tolerance of HCV, impairment of immune response and even further virus persistence. This occult infection grows more important in transplantation.

  5. Ionospheric Signatures in Radio Occultation Data

    Science.gov (United States)

    Mannucci, Anthony J.; Ao, Chi; Iijima, Byron A.; Kursinkski, E. Robert

    2012-01-01

    We can extend robustly the radio occultation data record by 6 years (+60%) by developing a singlefrequency processing method for GPS/MET data. We will produce a calibrated data set with profile-byprofile data characterization to determine robust upper bounds on ionospheric bias. Part of an effort to produce a calibrated RO data set addressing other key error sources such as upper boundary initialization. Planned: AIRS-GPS water vapor cross validation (water vapor climatology and trends).

  6. Paraneoplastic retinopathy associated with occult bladder cancer

    DEFF Research Database (Denmark)

    Nivean, M; Muttuvelu, Danson V; Afzelius, Pia Maria Tullia

    2016-01-01

    The aim was to report the first case of cancer-associated retinopathy (CAR) presenting before bladder cancer diagnosis. A 71-year-old woman with a history of bilateral vision loss underwent subsequent complete ophthalmic examination include a fluorescein angiography, full-field electroretinogram ...... photoreceptor dysfunction, confirmed by ERG, should alert to a possible remote effect of known or occult malignancy. In the latter, PET-CT may be exploited as a powerful diagnostic tool....

  7. Behavior of zonal mean aerosol extinction ratio and its relationship with zonal mean temperature during the winter 1978-1979 stratospheric warming

    Science.gov (United States)

    Wang, P.-H.; Mccormick, M. P.

    1985-01-01

    The behavior of the zonal mean aerosol extinction ratio in the lower stratosphere near 75 deg N and its relationship with the zonal mean temperature during the January-February 1979 stratospheric sudden warming have been investigated based on the satellite sensor SAM II (Stratospheric Aerosol Measurement) and auxiliary meteorological measurements. The results indicate that distinct changes in the zonal mean aerosol extinction ratio occurred during this stratospheric sudden warming. It is also found that horizontal eddy transport due to planetary waves may have played a significant role in determining the distribution of the zonal mean aerosol extinction ratio.

  8. OCCULTISM AND MEDIUMSHIP IN FERNANDO PESSOA

    Directory of Open Access Journals (Sweden)

    Alisson Diêgo Dias de Medeiros

    2016-03-01

    Full Text Available This work is the result of a research on the influence that the occultism had on the work of the Portuguese poet Fernando Pessoa. To delimitate the study, we selected papers of Fernando Pessoa, which  suggested that the poet considered himself medium, and hence influenced his work, building his depersonalization. This work presents, thus, as main objectiveto analyze personal papers of Fernando Pessoa, whose outstanding characteristic is the presence of occultism and the supposed mediumship defended by him in response to non-literary and heteronymic manifestations. To this end, I focused on specific objectives, which are: a to study the speech of Fernando Pessoa on his supposed mediumship / occultism b to analyze specific texts that are, for the poet, mediumistic manifestations c to study excerpts from a set of personal letters in which Fernando Pessoa suggested being a medium. It is true that this dissertation will address many discussions already made by scholars and specialists in Fernando Pessoa, but we consider the possibility to deepen issues and contribute to the critical fortune of the poet.

  9. Understanding Nonlinear Saturation in Zonal-Flow-Dominated ITG Turbulence

    CERN Document Server

    Plunk, G G; Jenko, F

    2014-01-01

    We propose a quantitative model of the mode saturation, zonal flow (ZF) regulation and energy cascade that governs ion temperature gradient (ITG) turbulence in magnetized plasmas. Our model is formulated in terms of observable quantities, and tested in detail against numerical simulations to confirm that both its assumptions and predictions are satisfied. Key results include (1) a sensitivity of the nonlinear zonal flow response to the energy content of the ITG mode, (2) a persistence of ZF-controlled saturation at very high temperature gradients, (3) a physical explanation in terms of secondary and tertiary instabilities, and (4) dependence of heat flux in terms of dimensionless parameters at high drive strength. Our findings reconcile ostensibly divergent views on the basic theory of ITG turbulence.

  10. Statistical properties of Charney-Hasegawa-Mima zonal flows

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Johan, E-mail: anderson.johan@gmail.com [Department of Earth and Space Sciences, Chalmers University of Technology, SE-412 96 Göteborg (Sweden); Botha, G. J. J. [Department of Mathematics and Information Sciences, Northumbria University, Newcastle Upon Tyne NE1 8ST (United Kingdom)

    2015-05-15

    A theoretical interpretation of numerically generated probability density functions (PDFs) of intermittent plasma transport events in unforced zonal flows is provided within the Charney-Hasegawa-Mima (CHM) model. The governing equation is solved numerically with various prescribed density gradients that are designed to produce different configurations of parallel and anti-parallel streams. Long-lasting vortices form whose flow is governed by the zonal streams. It is found that the numerically generated PDFs can be matched with analytical predictions of PDFs based on the instanton method by removing the autocorrelations from the time series. In many instances, the statistics generated by the CHM dynamics relaxes to Gaussian distributions for both the electrostatic and vorticity perturbations, whereas in areas with strong nonlinear interactions it is found that the PDFs are exponentially distributed.

  11. The stability of a zonally averaged thermohaline circulation model

    CERN Document Server

    Schmidt, G A

    1995-01-01

    A combination of analytical and numerical techniques are used to efficiently determine the qualitative and quantitative behaviour of a one-basin zonally averaged thermohaline circulation ocean model. In contrast to earlier studies which use time stepping to find the steady solutions, the steady state equations are first solved directly to obtain the multiple equilibria under identical mixed boundary conditions. This approach is based on the differentiability of the governing equations and especially the convection scheme. A linear stability analysis is then performed, in which the normal modes and corresponding eigenvalues are found for the various equilibrium states. Resonant periodic solutions superimposed on these states are predicted for various types of forcing. The results are used to gain insight into the solutions obtained by Mysak, Stocker and Huang in a previous numerical study in which the eddy diffusivities were varied in a randomly forced one-basin zonally averaged model. Resonant stable oscillat...

  12. [Occult hepatitis B virus infection in chronic hepatitis C].

    Science.gov (United States)

    Jang, Jae Young; Park, Eui Ju

    2013-09-01

    Occult HBV infection is defined as the presence of HBV DNA in the liver (with or without detectable or undetectable HBV DNA in the serum) of individuals testing negative for HBsAg. Studies on occult HBV infection in hepatitis C patients have reported highly variable prevalence, because the prevalence of occult HBV infection varies depending on the hepatitis B risk factors and methodological approaches. The most reliable diagnostic approach for detecting occult HBV detection is through examination of liver DNA extracts. HCV has been suspected to strongly suppress HBV replication up to the point where it may be directly responsible for occult HBV infection development. However, more data are needed to arrive at a definitive conclusion regarding the role of HCV in inducing occult HBV infection. Occult HBV infection in chronic hepatitis C patients is a complex biological entity with possible relevant clinical implications. Influence of occult HBV infection on the clinical outcomes of chronic hepatitis C may be considered negative. However, recent studies have shown that occult HBV infection could be associated with the development of hepatocellular carcinoma and contribute to the worsening of the course of chronic liver disease over time in chronic hepatitis C patients. Nevertheless, the possible role of occult HBV infection in chronic hepatitis C is still unresolved and no firm conclusion has been made up until now. It still remains unclear how occult HBV infection affects the treatment of chronic hepatitis C. Therefore, in order to resolve current controversies and understand the pathogenic role and clinical impacts of occult HBV infection in chronic hepatitis C patients, well-designed clinical studies are needed.

  13. OCCULT-ORSER complete conversational user-language translator

    Science.gov (United States)

    Ramapriyan, H. K.; Young, K.

    1981-01-01

    Translator program (OCCULT) assists non-computer-oriented users in setting up and submitting jobs for complex ORSER system. ORSER is collection of image processing programs for analyzing remotely sensed data. OCCULT is designed for those who would like to use ORSER but cannot justify acquiring and maintaining necessary proficiency in Remote Job Entry Language, Job Control Language, and control-card formats. OCCULT is written in FORTRAN IV and OS Assembler for interactive execution.

  14. What can the Occult do for you? STarlight Attenuation & Reddening Survey of Multiple Occulting Galaxies (STARSMOG)

    CERN Document Server

    Holwerda, B W

    2015-01-01

    Interstellar dust is still the dominant uncertainty in Astronomy, limiting precision in e.g., cosmological distance estimates and models of how light is re-processed within a galaxy. When a foreground galaxy serendipitously overlaps a more distant one, the latter backlights the dusty structures in the nearer foreground galaxy. Such an overlapping or occulting galaxy pair can be used to measure the distribution of dust in the closest galaxy with great accuracy. The STARSMOG program uses HST observation of occulting galaxy pairs to accurately map the distribution of dust in foreground galaxies in fine ($<$100 pc) detail. Furthermore, Integral Field Unit observations of such pairs will map the effective extinction curve in these occulting galaxies, disentangling the role of fine-scale geometry and grain composition on the path of light through a galaxy. The overlapping galaxy technique promises to deliver a clear understanding of the dust in galaxies: the dust geometry, a probability function of the amount of...

  15. Analysis of Venusian Zonal Winds Using Venus Express Data

    Science.gov (United States)

    McCabe, Ryan M.; Sayanagi, Kunio M.; Blalock, John J.; Peralta, Javier; Gray, Candace L.; McGouldrick, Kevin; Imamura, Takeshi

    2016-10-01

    We measure the zonal mean wind structure of Venus between 2006 and 2013 in the ultraviolet images captured by the Venus Monitoring Camera (VMC) onboard the ESA Venus Express spacecraft. Our wind measurements employ the digital two-dimensional Correlation Imaging Velocimetry method to track cloud motions. Our current focus is on understanding the short- and long-term dynamics of Venus's atmospheric superrotation, in which the equatorial atmosphere rotates with a period of approximately 4-5 days (~60 times faster than the solid planet). The Venusian atmospheric superrotation's forcing and maintenance mechanisms remain to be explained. A number of studies have been published on the cloud-tracking wind measurements on Venus, however, those different measurements have not reached a consensus on the temporal evolution of the zonal wind structure (e.g., Kouyama et al 2013, Khatuntsev et al 2013, Patsaeva et al. 2015). Temporal evolution of the zonal wind could reveal the transport of energy and momentum and eventually shed a light on mechanisms that maintain the superrotation. Our first goal is to characterize the temporal dynamics of Venus's zonal wind profile and two-dimensional wind field, in which we will search for equatorial waves (in particular the so-called "Y-feature") that may force the Venusian atmospheric superrotation.Kouyama, T. et al (2013), J. Geophys. Res. Planets, 118, 37-46, doi:10.1029/2011JE004013.Khatuntsev et al. (2013), Icarus, 226, 140-158, doi:10.1016/j.icarus.2013.05.018.Patsaeva,M.V.,et al. (2015), Planetary and Space Science, 113, 100-108, doi:10.1016/j.pss.2015.01.013.

  16. Interaction of Moist Convection With Jupiter's Zonal Jets

    Science.gov (United States)

    Li, L.; Ingersoll, A. P.; Huang, X.

    2004-12-01

    Since Voyager times, observations have suggested that Jupiter's zonal jets violate the barotropic stability criterion (BSTC) (Ingersoll et al., 1981; Limaye, 1986; Li et al., in press). Recently, images from the Cassini Imaging Science System (ISS) (Porco et al., 2003; Li et al., in press) and from the Galileo imaging system (Little et al., 1999; Gierasch et al., 2000) have revealed important features of moist convection on Jupiter and suggest that moist convection may be driving the zonal jets. Here we investigate the interaction of moist convection with the zonal jets in a reduced-gravity quasi-geostrophic model using a moist convection parameterization that is based on the new observations. Our study shows that moist convection can excite multiple jets when the velocity of the flow in the deep underlying layer is zero, but these jets never violate the BSTC. However, based on a model of the interaction between the magnetic field and the zonal flow, Liu and Stevenson (2003, DPS 35th meeting) predict that there are easterly flows in the deep underlying layer at middle latitudes. With easterly flows in the deep underlying layer we can get stable multiple jets that violate the BSTC. Furthermore, the modeled jets have almost same width and amplitude as the observed jets. An easterly flow in the lower layer provides a simple explanation for why the upper layer jets are stable even though they violate the BSTC. The model reproduces the tilted, chevron-shaped cloud features provided we assume that the clouds persist longer than the moist convective storms that produce them.

  17. The Generalized Quasilinear Approximation: Application to Zonal Jets

    CERN Document Server

    Marston, J B; Tobias, S M

    2016-01-01

    Quasilinear theory is often utilized to approximate the dynamics of fluids exhibiting significant interactions between mean flows and eddies. In this paper we present a generalization of quasilinear theory to include dynamic mode interactions on the large scales. This generalized quasilinear (GQL) approximation is achieved by separating the state variables into large and small zonal scales via a spectral filter rather than by a decomposition into a formal mean and fluctuations. Nonlinear interactions involving only small zonal scales are then removed. The approximation is conservative and allows for scattering of energy between small-scale modes via the large scale (through non-local spectral interactions). We evaluate GQL for the paradigmatic problems of the driving of large-scale jets on a spherical surface and on the beta-plane and show that it is accurate even for a small number of large-scale modes. As this approximation is formally linear in the small zonal scales it allows for the closure of the system...

  18. The relevance of grid expansion under zonal markets

    Energy Technology Data Exchange (ETDEWEB)

    Bertsch, Joachim; Hagspiel, Simeon; Just, Lisa [ewi Energy Research and Scenarios gGmbH, Cologne (Germany); Cologne Univ. (Germany). Dept. of Economics; Brown, Tom [Frankfurt Institute of Advanced Studies (Germany)

    2015-12-15

    The European electricity market design is based on zonal markets with uniform prices. Locational price signals within these zones - necessary to ensure long-term efficiency - are not provided. Specifically, if intra-zonal congestion occurs due to missing grid expansion, the market design is revealed as inherently incomplete. This might lead to severe, unwanted distortions of the electricity market, both in the short- and in the long-term. In this paper, we study these distortions with a specific focus on the impact of restricted grid expansion under zonal markets. For this, we use a long term fundamental dispatch and investment model of the European electricity system and gradually restrict the allowed expansion of the transmission grid per decade. We find that the combination of an incomplete market design and restricted grid expansion leads to a misallocation of generation capacities and the inability to transport electricity to where it is needed. Consequences are severe and lead to load curtailment of up to 2-3 %. Moreover, missing grid expansion makes it difficult and costly to reach envisaged energy targets in the power sector. Hence, we argue that in the likely event of restricted grid expansion, either administrative measures or - presumably more efficient - an adaptation of the current market design to include locational signals will become necessary.

  19. Ipsilateral occult hernias during endoscopic groin hernia repair

    Directory of Open Access Journals (Sweden)

    Jain Mayank

    2008-01-01

    Full Text Available Endoscopic repair of groin hernias allows the surgeon to have a complete view of the groin and pelvis to diagnose occult hernias both ipsilaterally and contralaterally. These occult hernias can then be treated simultaneously and may reduce the incidence of recurrence and persistent symptoms. The authors present four unusual cases where occult hernias were found ipsilaterally during an endoscopic repair. All these occult hernias were treated along with the clinically diagnosed hernia at the same surgery with excellent results and no post-operative morbidity.

  20. Survey of the initial management and imaging protocols for occult scaphoid fractures in UK hospitals

    Energy Technology Data Exchange (ETDEWEB)

    Brookes-Fazakerley, S.D.; Kumar, A.J.S. [Countess of Chester Hospital NHS Foundation Trust, Department of Trauma and Orthopaedics, Chester (United Kingdom); Oakley, J. [Robert Jones and Agnes Hunt Orthopaedic and District Hospital NHS Trust, Oswestry, Shropshire (United Kingdom)

    2009-11-15

    The aim of this research was to survey how occult fractures of the scaphoid bone are both imaged and managed initially. A total of 832 questionnaires were sent via e-mail to active associate members of the British Orthopaedic Association. Included was a series of questions regarding the timing of initial and subsequent orthopaedic review of this group of patients and the use of serial radiographs and second-line imaging techniques. Nearly half of the UK's acute NHS trusts were represented (45%). The response rate was 16% (130 out of 832). Only 16% of respondents were aware of a local imaging protocol for the investigation of suspected fractures of the scaphoid. Ninety-four percent of respondents performed a second radiograph at first fracture clinic review. Fifty-eight percent used magnetic resonance imaging (MRI) as a second-line investigation; with computed tomography scan and radionuclide isotope bone scan being performed by 26% and 16% respondents, respectively. The survey revealed a wide variation in the management of occult fractures of the scaphoid. MRI has been shown to be both sensitive and specific in diagnosing occult carpal bone fractures. There is a need to standardise the management of these injuries to ensure early diagnosis and limit unnecessary wrist immobilisation. (orig.)

  1. The use of MRI and CT in Imaging Occult Hip Fractures

    Directory of Open Access Journals (Sweden)

    Obadă B.

    2014-11-01

    Full Text Available Diagnosis of hip fractures is particularly important due to the high dependence on the integrity of this structure for people to function in their daily lives. Left unrecognized, patients face increasing morbidity and mortality as time from the original injury lengthens. A delay of just 2 days in surgical treatment for an acute hip fracture doubles mortality. In addition, an unrecognized non-displaced fracture may displace, requiring surgery of much higher risk. This may be part of the reason that the most frequent lawsuit against Emergency Physicians is for missed orthopedic injury. We reviewed the use of MRI and CT for occult hip fractures (OHF detection at a major urban trauma unit. Our study is a retrospective review. Inclusion criteria: all patients presenting to the Emergency Clinical Hospital of Constanta with a suspected, posttraumatic, occult hip fracture, over a 5 years period were included. All patients had negative initial radiographs and underwent further imaging with either CT or MRI. A total of 185 cases meeting the inclusion criteria were identified. 72 occult hip fractures were detected with both imaging modalities. Although MRI certainly enables greater image detail, in our experience both modalities are able to provide satisfactory fracture characterization. The choice of imaging should be determined by availability and indication. MRI provides superior imaging of soft tissue but is less sensitive for degenerative changes in presence of bone edema.

  2. New perspectives in occult hepatitis C virus infection.

    Science.gov (United States)

    Carreño, Vicente; Bartolomé, Javier; Castillo, Inmaculada; Quiroga, Juan Antonio

    2012-06-21

    Occult hepatitis C virus (HCV) infection, defined as the presence of HCV RNA in liver and in peripheral blood mononuclear cells (PBMCs) in the absence of detectable viral RNA in serum by standard assays, can be found in anti-HCV positive patients with normal serum levels of liver enzymes and in anti-HCV negative patients with persistently elevated liver enzymes of unknown etiology. Occult HCV infection is distributed worldwide and all HCV genotypes seem to be involved in this infection. Occult hepatitis C has been found not only in anti-HCV positive subjects with normal values of liver enzymes or in chronic hepatitis of unknown origin but also in several groups at risk for HCV infection such as hemodialysis patients or family members of patients with occult HCV. This occult infection has been reported also in healthy populations without evidence of liver disease. Occult HCV infection seems to be less aggressive than chronic hepatitis C although patients affected by occult HCV may develop liver cirrhosis and even hepatocellular carcinoma. Thus, anti-HCV negative patients with occult HCV may benefit from antiviral therapy with pegylated-interferon plus ribavirin. The persistence of very low levels of HCV RNA in serum and in PBMCs, along with the maintenance of specific T-cell responses against HCV-antigens observed during a long-term follow-up of patients with occult hepatitis C, indicate that occult HCV is a persistent infection that is not spontaneously eradicated. This is an updated report on diagnosis, epidemiology and clinical implications of occult HCV with special emphasis on anti-HCV negative cases.

  3. New perspectives in occult hepatitis C virus infection

    Institute of Scientific and Technical Information of China (English)

    Vicente Carre(n)o; Javier Bartolomé; Inmaculada Castillo; Juan Antonio Quiroga

    2012-01-01

    Occult hepatitis C virus (HCV) infection,defined as the presence of HCV RNA in liver and in peripheral blood mononuclear cells (PBMCs) in the absence of detectable viral RNA in serum by standard assays,can be found in anti-HCV positive patients with normal serum levels of liver enzymes and in anti-HCV negative patients with persistently elevated liver enzymes of unknown etiology.Occult HCV infection is distributed worldwide and all HCV genotypes seem to be involved in this infection.Occult hepatitis C has been found not only in anti-HCV positive subjects with normal values of liver enzymes or in chronic hepatitis of unknown origin but also in several groups at risk for HCV infection such as hemodialysis patients or family members of patients with occult HCV.This occult infection has been reported also in healthy populations without evidence of liver disease.Occult HCV infection seems to be less aggressive than chronic hepatitis C although patients affected by occult HCV may develop liver cirrhosis and even hepatocellular carcinoma.Thus,anti-HCV negative patients with occult HCV may benefit from antiviral therapy with pegylatedinterferon plus ribavirin.The persistence of very low levels of HCV RNA in serum and in PBMCs,along with the maintenance of specific T-cell responses against HCV-antigens observed during a long-term follow-up of patients with occult hepatitis C,indicate that occult HCV is a persistent infection that is not spontaneously eradicated.This is an updated report on diagnosis,epidemiology and clinical implications of occult HCV with special emphasis on anti-HCV negative cases.

  4. Occult gastrointestinal bleeding in high-risk intensive care unit patients receiving antacid prophylaxis: frequency and significance.

    Science.gov (United States)

    Derrida, S; Nury, B; Slama, R; Marois, F; Moreau, R; Soupison, T; Sicot, C

    1989-02-01

    Gastroccult reagent was used every 4 h to detect blood in gastric juice in 41 ICU patients at risk of GI bleeding (GB) and receiving antacid prophylaxis (gastric pH greater than 3.5). Of the present patients, 27% (11/41) had at least one episode of occult GB (three consecutive positive determinations; a total of 14 episodes). Endoscopy identified acute gastroduodenal mucosal lesions (stress ulcers) as the most frequent lesion in this group (eight patients). Sepsis was the most frequent underlying condition associated with occult GB due to stress ulcer. Hematemesis occurred in 36% (4/11) of patients with occult GB and was due to stress ulcer in three patients and to benign gastric tumor in one. No overt GB occurred in the absence of previous occult GB. We conclude that: a) risk of GB persists in critically ill ICU patients in spite of antacid prophylaxis (gastric pH greater than 3.5); b) high-risk patients can be identified through periodic testing for the presence of blood in gastric juice using the reagent; c) when occult GB occurs, treatment should be based on the endoscopy results. In the absence of acute gastroduodenal mucosal lesions, antacid prophylaxis should not be modified, and specific treatment of the identified lesion(s) should be initiated. In the presence of stress lesions, antacid prophylaxis should be reinforced if the pH of the gastric content is less than 3.5 and a septic complication should be actively sought if the pH is greater than 3.5.

  5. Data analysis of 2005 Regulus occultation and simulation of the 2014 occultation

    CERN Document Server

    Sigismondi, Costantino; Flatrès, Thomas

    2014-01-01

    On March 20, 2014 at 6:06 UT (2:06 New York time) Regulus, the 1.3 magnitude brighter star of Leo constellation, is going to be occulted by the asteroid 163 Erigone. The unusual event, visible to the naked eye over NYC, can allow to measure the shape of the asteroid, with reaching a space resolution below the diffraction limit of the eye, and of all instruments not based on interferometry. Ultimately the aperture of the instrument is related to the amount of scintillation affecting the light curve of the occultation, limitating the accuracy of video recorded data. The asteroid profile scans the surface of the star at a velocity of 6 mas/s; the diameter of the star is about 1.3 mas and the detection of the stellar limb darkening signature is discussed, taking into consideration also the Fresnel fringes. New data reduction with R-OTE software of the 2005 Regulus occultation and simulations of the 2014 occultation with Fren_difl software are presented.

  6. Asymptomatic Hepadnaviral Persistence and Its Consequences in the Woodchuck Model of Occult Hepatitis B Virus Infection.

    Science.gov (United States)

    Mulrooney-Cousins, Patricia M; Michalak, Tomasz I

    2015-09-28

    Woodchuck hepatitis virus (WHV) is molecularly and pathogenically closely related to hepatitis B virus (HBV). Both viruses display tropism towards hepatocytes and cells of the immune system and cause similar liver pathology, where acute hepatitis can progress to chronic hepatitis and to hepatocellular carcinoma (HCC). Two forms of occult hepadnaviral persistence were identified in the woodchuck-WHV model: secondary occult infection (SOI) and primary occult infection (POI). SOI occurs after resolution of a serologically apparent infection with hepatitis or after subclinical serologically evident virus exposure. POI is caused by small amounts of virus and progresses without serological infection markers, but the virus genome and its replication are detectable in the immune system and with time in the liver. SOI can be accompanied by minimal hepatitis, while the hallmark of POI is normal liver morphology. Nonetheless, HCC develops in about 20% of animals with SOI or POI within 3 to 5 years. The virus persists throughout the lifespan in both SOI and POI at serum levels rarely greater than 100 copies/mL, causes hepatitis and HCC when concentrated and administered to virus-naïve woodchucks. SOI is accompanied by virus-specific T and B cell immune responses, while only virus-specific T cells are detected in POI. SOI coincides with protection against reinfection, while POI does not and hepatitis develops after challenge with liver pathogenic doses >1000 virions. Both SOI and POI are associated with virus DNA integration into the liver and the immune system genomes. Overall, SOI and POI are two distinct forms of silent hepadnaviral persistence that share common characteristics. Here, we review findings from the woodchuck model and discuss the relevant observations made in human occult HBV infection (OBI).

  7. Categorizing the Occult: Vodun, Sorcery and Religious Beliefs In Benin

    DEFF Research Database (Denmark)

    Strandsbjerg, Camilla

    2011-01-01

    characterized as witchcraft or occult. Reflecting upon earlier research and particularly on the choice of terminology of the occult in writing on religion and political change in Benin (PhD thesis 2008), this paper seeks to clarify some of the epistemological, academic and historical reasons that have formed...

  8. The Treatment of the Occult in General Encyclopedias.

    Science.gov (United States)

    Sonnenfeld, Gary F.

    This paper is a content analysis of three general encyclopedias, "Encyclopedia Americana" (EA), "Encyclopaedia Brittanica" (EB), and "World Book Encyclopedia" (WBC), which quantifies the treatment of the occult. Entries are selected from each by starting with the article "Occultism" and tracing all…

  9. Prevalence of occult hepatitis B virus infection

    Institute of Scientific and Technical Information of China (English)

    Maria Luisa Gutiérrez-García; Conrado M Fernandez-Rodriguez; Jose Luis Lledo-Navarro; Ingrid Buhigas-Garcia

    2011-01-01

    Occult hepatitis B virus (HBV) infection (OBI) is characterized by the persistence of HBV DNA in the liver tissue in individuals negative for the HBV surface antigen. The prevalence of OBI is quite variable depending on the level of endemic disease in different parts of the world,the different assays utilized in the studies, and the different populations studied. Many studies have been carried out on OBI prevalence in different areas of the world and categories of individuals. The studies show that OBI prevalence seems to be higher among subjects at high risk for HBV infection and with liver disease than among individuals at low risk of infection and without liver disease.

  10. Wave Optics Based LEO-LEO Radio Occultation Retrieval

    DEFF Research Database (Denmark)

    von Benzon, Hans-Henrik; Høeg, Per

    2016-01-01

    This paper describes the theory for performing retrieval of radio occultations that use probing frequencies in the XK and KM band. Normally radio occultations use frequencies in the L band and GPS satellites are used as the transmitting source and the occultation signals are received by a GPS...... in the signal amplitude caused by atmospheric absorption. The radio wave transmitter is placed on one of these satellites while the receiver is placed on the other LEO satellite. One of the drawbacks of normal GPS based radio occultations is that external information is needed to calculate some...... chain is therefore a wave optics based retrieval chain and it is therefore possible to process measurements that include multipath. In this paper simulated LEO to LEO radio occultations based on 5 different frequencies are used. The 5 frequencies are placed in the XK or KM frequency band. This new wave...

  11. A digital video system for observing and recording occultations

    CERN Document Server

    Barry, M A; Pavlov, Hristo; Hanna, William; McEwan, Alistair; Filipovic, Miroslav

    2015-01-01

    Stellar occultations by asteroids and outer solar system bodies can offer ground based observers with modest telescopes and camera equipment the opportunity to probe the shape, size, atmosphere and attendant moons or rings of these distant objects. The essential requirements of the camera and recording equipment are: good quantum efficiency and low noise, minimal dead time between images, good horological faithfulness of the image time stamps, robustness of the recording to unexpected failure, and low cost. We describe the Astronomical Digital Video occultation observing and recording System (ADVS) which attempts to fulfil these requirements and compare the system with other reported camera and recorder systems. Five systems have been built, deployed and tested over the past three years, and we report on three representative occultation observations: one being a 9 +/-1.5 second occultation of the trans-Neptunian object 28978 Ixion (mv=15.2) at 3 seconds per frame, one being a 1.51 +/-0.017 second occultation ...

  12. Effects of Zonal Wind on Stratospheric Ozone Variations over Nigeria

    Science.gov (United States)

    Chidinma Okoro, Eucharia,

    2016-07-01

    The effects of zonal wind on stratospheric ozone variation over Nigeria have been studied. The areas covered in this study include; Maiduguri, Ikeja, Port-Harcourt, Calabar, Makurdi, Ilorin, Akure, Yola, Minna, Jos, Kano and Enugu in Nigeria, from 1986 to 2008. Zonal wind was computed from the iso-velocity map employing MATLAB software. The mean monthly variations of AAM and LOD at pressure levels of 20, 30 and 50 mb in the atmosphere depict a trend of maximum amplitude between April and September, and minimum amplitude between December and March. The trend observed in seasonal variation of O3 column data in the low latitude had maximum amount from May through August and minimum values from December through February. The mean monthly maximum O3 concentrations was found to be 284.70 Du (Kano) occurring in May 1989 while, an average monthly minimum O3 concentration was found to be 235.60 Du (Port-Harcourt and Calabar) occurring in January 1998. It has been established in this study that, the variation in atmospheric angular momentum (AAM) caused by variation of the universal time or length of day (LOD) transfer ozone (O3) by means of zonal wind from the upper troposphere to the lower stratosphere in the stations understudy. The strong effect of the pressure levels of the atmosphere on O3 variation could be attributed to its effect on the AAM and LOD. Variation in the LOD is significant in the tropics, suggesting that, the effects of the extra-tropical suction pump (ETSP) action is not the only driver responsible for O3 transportation from the tropics to extra-tropical zones. Consequently, these findings lead to a deduction that weather pattern alteration observed due to these changes could lead to climate change. Keywords: ozone variations; dynamical processes; harmattan wind; ETSP; and climatic variability

  13. Thermospheric zonal temperature gradients observed at low latitudes

    Directory of Open Access Journals (Sweden)

    P. R. Fagundes

    Full Text Available Fabry-Perot interferometer (FPI measurements of thermospheric temperatures from the Doppler widths of the OI 630 nm nightglow emission line have been carried out at Cachoeira Paulista (23° S, 45° W, 16° S dip latitude, Brazil. The east-west components of the thermospheric temperatures obtained on 73 nights during the period from 1988 to 1992, primarily under quiet geomagnetic conditions, were analyzed and are presented in this paper. It was observed that on 67% of these nights, the temperatures in both the east and west sectors presented similar values and nocturnal variations. However, during 33% of the nights, the observed temperatures in the west sector were usually higher than those observed in the east sector, with zonal temperature gradients in the range of 100 K to 600 K, over about an 800 km horizontal distance. Also, in some cases, the observed temperatures in the east and west sectors show different nocturnal variations. One of the possible sources considered for the observed zonal temperature gradients is the influence of gravity wave dissipation effects due to waves that propagate from lower altitudes to thermospheric heights. The observed zonal temperature gradients could also be produced by orographic gravity waves originated away, over the Andes Cordillera in the Pacific Sector, or by dissipation of orographic gravity waves generated over the Mantiqueira Mountains in the Atlantic sector by tropospheric disturbances (fronts and/or subtropical jet streams.

    Key words. Atmospheric composition and structure (air-glow and aurora; thermosphere - composition and chemistry Ionosphere (equatorial ionosphere

  14. Magnetic flux concentration and zonal flows in magnetorotational instability turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Xue-Ning [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-51, Cambridge, MA 02138 (United States); Stone, James M., E-mail: xbai@cfa.harvard.edu [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States)

    2014-11-20

    Accretion disks are likely threaded by external vertical magnetic flux, which enhances the level of turbulence via the magnetorotational instability (MRI). Using shearing-box simulations, we find that such external magnetic flux also strongly enhances the amplitude of banded radial density variations known as zonal flows. Moreover, we report that vertical magnetic flux is strongly concentrated toward low-density regions of the zonal flow. Mean vertical magnetic field can be more than doubled in low-density regions, and reduced to nearly zero in high-density regions in some cases. In ideal MHD, the scale on which magnetic flux concentrates can reach a few disk scale heights. In the non-ideal MHD regime with strong ambipolar diffusion, magnetic flux is concentrated into thin axisymmetric shells at some enhanced level, whose size is typically less than half a scale height. We show that magnetic flux concentration is closely related to the fact that the turbulent diffusivity of the MRI turbulence is anisotropic. In addition to a conventional Ohmic-like turbulent resistivity, we find that there is a correlation between the vertical velocity and horizontal magnetic field fluctuations that produces a mean electric field that acts to anti-diffuse the vertical magnetic flux. The anisotropic turbulent diffusivity has analogies to the Hall effect, and may have important implications for magnetic flux transport in accretion disks. The physical origin of magnetic flux concentration may be related to the development of channel flows followed by magnetic reconnection, which acts to decrease the mass-to-flux ratio in localized regions. The association of enhanced zonal flows with magnetic flux concentration may lead to global pressure bumps in protoplanetary disks that helps trap dust particles and facilitates planet formation.

  15. Zonal flow regimes in rotating anelastic spherical shells (Invited)

    Science.gov (United States)

    Gastine, T.; Wicht, J.; Aurnou, J. M.; Heimpel, M. H.

    2013-12-01

    The surface zonal winds observed in the giant planets form a complex jet pattern with alternating prograde and retrograde direction. While the main equatorial band is prograde on the gas giants, both ice giants have a pronounced retrograde equatorial jet. The depth of these jets is however poorly known and highly debated. Theoretical scenarios range from "shallow models", that assume that these zonal flows are restricted to the outer stably stratified layer; to "deep models" that hypothesise that the surface winds are the signature of deep-seated convection. Most of the numerical models supporting the latter idea employed the Boussinesq approximation where compressibility effects are ignored. While this approximation is suitable for modelling the liquid iron core of terrestrial planets, this becomes questionable in the gas giants interiors, where density increases by several orders of magnitude. To tackle this problem, several numerical models using the "anelastic approximation" have been recently developed to study the compressibility effects while filtering out the fast acoustic waves. Here, we consider such anelastic models of rapidly-rotating spherical shells to explore the properties of the zonal winds in different regimes where either rotation or buoyancy dominates the force balance. We conduct several parameter studies to quantify the dependence of zonal flows on the background density stratification and the driving of convection. We find that the direction of the equatorial wind is controlled by the ratio of buoyancy and Coriolis force. The prograde equatorial band maintained by Reynolds stresses is found in the rotation-dominated regime. At low Ekman numbers, several alternating jets form at high latitude in a similar way to some previous Boussinesq calculations. In cases where buoyancy dominates Coriolis force, the angular momentum per unit mass is homogenised and the equatorial band is retrograde, reminiscent to those observed in the ice giants

  16. Radio occultation experiments with INAF-IRA radiotelescopes.

    Science.gov (United States)

    Pluchino, S.; Schillirò, F.; Salerno, E.; Pupillo, G.

    The Radio Occultation research program performed at the Medicina and Noto Radioastronomical Stations of the Istituto Nazionale di Astrofisica (INAF) - Istituto di Radioastronomia (IRA) includes observations of spacecraft by satellite and satellite by satellite events. The Lunar Radio Occultation (LRO) part of the program consists in collecting data of the lunar Total Electron Content (TEC), at different limb longitudes and at different time, in order to study long term variation of the Moon's ionosphere. The LRO program started at Medicina in September 2006 with the observation of the European probe SMART-1 during its impact on the lunar soil. It proceeded in 2007 with the observation of the lunar occultations of Saturn and Venus, and with the observation of Mars in 2008. On this occasion the probes Cassini, Venus Express, Mars Express, Mars Reconaissance Orbiter and Mars Odissey were respectively occulted by the moon. On Dec 1st 2008 a Venus lunar occultation occurred. On that occasion we performed the first Italian-VLBI (I-VLBI) tracking experiment by detecting the carrier signals coming from the Venus Express (VEX) spacecraft with both the IRA radiotelescopes together with the Matera antenna of the Italian Space Agency. The second part of the radio occultation program includes the observation of satellite by satellite occultation events, as well as mutual occultations of Jupiter satellites. These events are referred to as mutual phenomena (PHEMU). These observations are aimed to measure the radio flux variation during the occultation and to derive surface spatial characteristics such as Io's hot spots. In this work preliminary results of the Radio Occultation program will be presented.

  17. Experimental studies of zonal flow and field in compact helical system plasmaa)

    Science.gov (United States)

    Fujisawa, A.; Itoh, K.; Shimizu, A.; Nakano, H.; Ohshima, S.; Iguchi, H.; Matsuoka, K.; Okamura, S.; Minami, T.; Yoshimura, Y.; Nagaoka, K.; Ida, K.; Toi, K.; Takahashi, C.; Kojima, M.; Nishimura, S.; Isobe, M.; Suzuki, C.; Akiyama, T.; Ido, T.; Nagashima, Y.; Itoh, S.-I.; Diamond, P. H.

    2008-05-01

    The experimental studies on zonal flows and turbulence have been carried out in Compact Helical System [K. Matsuoka, S. Kubo, M. Hosokawa et al., in Plasma Physics and Controlled Nuclear Fusion Research, Proc. 12th Int. Conf., Nice, 1988 (International Atomic Energy Agency, Vienna, 1989, Vol. 2, p. 411] using twin heavy ion beam probes. The paper presents the experimental observations of stationary zonal flow, nonlinear couplings between zonal flow and turbulence, and the role of zonal flow in the improved confinement, together with the recent discovery of zonal magnetic field. The presented experimental results strongly support the new paradigm that the plasma transport should be considered as a system of drift wave and zonal flows, and provides the first direct evidence for turbulence dynamo that the structured magnetic field can be really generated by turbulence.

  18. Non-axisymmetric instabilities in discs with imposed zonal flows

    Science.gov (United States)

    Vanon, R.; Ogilvie, G. I.

    2016-12-01

    We conduct a linear stability calculation of an ideal Keplerian flow on which a sinusoidal zonal flow is imposed. The analysis uses the shearing sheet model and is carried out both in isothermal and adiabatic conditions, with and without self-gravity (SG). In the non-SG regime, a structure in the potential vorticity (PV) leads to a non-axisymmetric Kelvin-Helmholtz (KH) instability; in the short-wavelength limit its growth rate agrees with the incompressible calculation by Lithwick, which only considers perturbations elongated in the streamwise direction. The instability's strength is analysed as a function of the structure's properties, and zonal flows are found to be stable if their wavelength is ≳8 H, where H is the disc's scaleheight, regardless of the value of the adiabatic index γ. The non-axisymmetric KH instability can operate in Rayleigh-stable conditions, and it therefore represents the limiting factor to the structure's properties. Introducing SG triggers a second non-axisymmetric instability, which is found to be located around a PV maximum, while the KH instability is linked to a PV minimum, as expected. In the adiabatic regime, the same gravitational instability is detected even when the structure is present only in the entropy (not in the PV) and the instability spreads to weaker SG conditions as the entropy structure's amplitude is increased. This eventually yields a non-axisymmetric instability in the non-SG regime, albeit of weak strength, localized around an entropy maximum.

  19. Zonal structure of unbounded external-flow and aerodynamics

    CERN Document Server

    Liu, Luoqin; Wu, Jiezhi

    2016-01-01

    This paper starts from the far-field behaviours of velocity field in externally-unbounded flow. We find that the well-known algebraic decay of disturbance velocity as derived kinematically is too conservative. Once the kinetics is taken into account by working on the fundamental solutions of far-field linearized Navier-Stokes equations, it is proven that the furthest far-field zone adjacent to the uniform fluid at infinity must be unsteady, viscous and compressible, where all disturbances degenerate to sound waves that decay exponentially. But this optimal rate does not exist in some commonly used simplified flow models, such as steady flow, incompressible flow and inviscid flow, because they actually work in true subspaces of the unbounded free space, which are surrounded by further far fields of different nature. This finding naturally leads to a zonal structure of externally-unbounded flow field. The significance of the zonal structure is demonstrated by its close relevance to existing theories of aerodyna...

  20. Effective Mass in Rosenbluth-Hinton type zonal flows

    CERN Document Server

    Sengupta, W

    2016-01-01

    An initial radial electric field, $E_r(0)$, in an axisymmetric tokamak, results in geodesic acoustic mode (GAM) oscillations. The GAMs Landau damp, resulting in a much smaller final residual electric field, $E_r(\\infty)$, and accompanying parallel zonal flows (Rosenbluth and Hinton, 1998 PRL 80, 724, hereafter RH). The phenomenon exhibits a large effective mass (inertia due to flows), with an enhancement of order the well-known RH factor. In apparent paradox, the final angular momentum in the RH parallel zonal flow is much smaller than the angular momentum expected from the well-known rapid precession of the trapped particle population in the final electric field. In addition, an effective mass calculated naively based on the rapid trapped particle (TP) precession is much larger than the RH factor. A drift kinetic calculation is presented showing that the mathematical origin of the extra mass factor is a shift, proportional to $E_r$, of the usual energy coordinates in phase space. Importantly, this shift cont...

  1. Non-axisymmetric instabilities in discs with imposed zonal flows

    CERN Document Server

    Vanon, R

    2016-01-01

    We conduct a linear stability calculation of an ideal Keplerian flow on which a sinusoidal zonal flow is imposed. The analysis uses the shearing sheet model and is carried out both in isothermal and adiabatic conditions, with and without self-gravity (SG). In the non-SG regime a structure in the potential vorticity (PV) leads to a non-axisymmetric Kelvin-Helmholtz (KH) instability; in the short-wavelength limit its growth rate agrees with the incompressible calculation by Lithwick (2007), which only considers perturbations elongated in the streamwise direction. The instability's strength is analysed as a function of the structure's properties, and zonal flows are found to be stable if their wavelength is $\\gtrsim 8H$, where $H$ is the disc's scale height, regardless of the value of the adiabatic index $\\gamma$. The non-axisymmetric KH instability can operate in Rayleigh-stable conditions, and it therefore represents the limiting factor to the structure's properties. Introducing SG triggers a second non-axisym...

  2. Zonal Flows Driven by Small-Scale Drift-Alfven Modes

    Institute of Scientific and Technical Information of China (English)

    李德徽; 周登

    2011-01-01

    Generation of zonal flows by small-scale drift-Alfven modes is investigated by adopting the approach of parametric instability with the electron polarization drift included. The zonal mode can be excited by primary modes propagating at both electron and ion diamagnetic drift directions in contrast to the assertion in previous studies that only primary modes propagating in the ion diamagnetic drift directions can drive zonal instabilities. Generally, the growth rate of the driven zonal mode is in the same order as that in previous study. However, different from the previous work, the growth rate is no longer proportional to the difference between the diamagnetic drift frequencies of electrons and ions.

  3. Fine Structure Zonal Flow Excitation by Beta-induced Alfven Eigenmode

    CERN Document Server

    Qiu, Zhiyong; Zonca, Fulvio

    2016-01-01

    Nonlinear excitation of low frequency zonal structure (LFZS) by beta-induced Alfven eigenmode (BAE) is investigated using nonlinear gyrokinetic theory. It is found that electrostatic zonal flow (ZF), rather than zonal current, is preferentially excited by finite amplitude BAE. In addition to the well-known meso-scale radial envelope structure, ZF is also found to exhibit fine radial structure due to the localization of BAE with respect to mode rational surfaces. Specifically, the zonal electric field has an even mode structure at the rational surface where radial envelope peaks.

  4. Review: Occult hepatitis C virus infection: still remains a controversy.

    Science.gov (United States)

    Vidimliski, Pavlina Dzekova; Nikolov, Igor; Geshkovska, Nadica Matevska; Dimovski, Aleksandar; Rostaing, Lionel; Sikole, Aleksandar

    2014-09-01

    Occult hepatitis C virus (HCV) infection is characterized by the presence of HCV RNA in the liver cells or peripheral blood mononuclear cells of the patients whose serum samples test negative for HCV RNA, with or without presence of HCV antibodies. The present study reviews the existing literature on the persistence of occult hepatitis C virus infection, with description of the clinical characteristics and methods for identification of occult hepatitis C. Occult hepatitis C virus infection was detected in patients with abnormal results of liver function tests of unknown origin, with HCV antibodies and HCV RNA negativity in serum, and also in patients with spontaneous or treatment-induced recovery from hepatitis C. The viral replication in the liver cells and/or peripheral blood mononuclear cells was present in all clinical presentations of occult hepatitis C. The peripheral blood mononuclear cells represent an extra-hepatic site of HCV replication. The reason why HCV RNA was not detectable in the serum of patients with occult hepatitis C, could be the low number of circulating viral particles not detectable by the diagnostic tests with low sensitivity. It is uncertain whether occult hepatitis C is a different clinical entity or just a form of chronic hepatitis C virus infection. Data accumulated over the last decade demonstrated that an effective approach to the diagnosis of HCV infection would be the implementation of more sensitive HCV RNA diagnostic assays, and also, examination of the presence of viral particles in the cells of the immune system.

  5. The Research and Education Collaborative Occultation Network: A System for Coordinated TNO Occultation Observations

    Science.gov (United States)

    Buie, Marc W.; Keller, John M.

    2016-03-01

    We describe a new system and method for collecting coordinated occultation observations of trans-Neptunian objects (TNOs). Occultations by objects in the outer solar system are more difficult to predict due to their large distance and limited span of the astrometric data used to determine their orbits and positions. This project brings together the research and educational community into a unique citizen-science partnership to overcome the difficulties of observing these distant objects. The goal of the project is to get sizes and shapes for TNOs with diameters larger than 100 km. As a result of the system design it will also serve as a probe for binary systems with spatial separations as small as contact systems. Traditional occultation efforts strive to get a prediction sufficiently good to place mobile ground stations in the shadow track. Our system takes a new approach of setting up a large number of fixed observing stations and letting the shadows come to the network. The nominal spacing of the stations is 50 km so that we ensure two chords at our limiting size. The spread of the network is roughly 2000 km along a roughly north-south line in the western United States. The network contains 56 stations that are committed to the project and we get additional ad hoc support from International Occultation Timing Association members. At our minimum size, two stations will record an event while the other stations will be probing the inner regions for secondary events. Larger objects will get more chords and will allow determination of shape profiles. The stations are almost exclusively sited and associated with schools, usually at the 9-12 grade level. We present a full description of the system we have developed for the continued exploration of the Kuiper Belt.

  6. Scattering and extinction: interpreting hazes in stellar occultation data

    Science.gov (United States)

    Bosh, Amanda S.; Levine, Stephen; Sickafoose, Amanda A.; Person, Michael J.

    2016-10-01

    There has been debate concerning interpretation of stellar occultation data and whether those data contain evidence for hazes within Pluto's atmosphere. Multiple layers of haze have been imaged in at Pluto with the New Horizons spacecraft; color-dependent differences in minimum flux from stellar occultations also suggests haze. We look at a purely geometric approach, to evaluate whether it is valid to sidestep details of atmospheric temperature structure and, in an approximate manner, conduct an analysis of the 2015 stellar occultation data that is consistent with the New Horizons imaging results. Support for this work was provided by NASA SSO grant NNX15AJ82G to Lowell Observatory.

  7. Verifying timestamps of occultation observation systems

    CERN Document Server

    A., M; Gault, Dave; Bolt, Greg; McEwan, Alistair; Filipovic, Miroslav D; White, Graeme L

    2015-01-01

    We describe an image timestamp verification system to determine the exposure timing characteristics and continuity of images made by an imaging camera and recorder, with reference to Coordinated Universal Time (UTC). The original use was to verify the timestamps of stellar occultation recording systems, but the system is applicable to lunar flashes, planetary transits, sprite recording, or any area where reliable timestamps are required. The system offers good temporal resolution (down to 2 msec, referred to UTC) and provides exposure duration and interframe dead time information. The system uses inexpensive, off-the- shelf components, requires minimal assembly and requires no high-voltage components or connections. We also describe an application to load FITS (and other format) image files, which can decode the verification image timestamp. Source code, wiring diagrams and built applications are provided to aid the construction and use of the device.

  8. Convective towers detection using GPS radio occultations

    DEFF Research Database (Denmark)

    Biondi, Riccardo; Neubert, Torsten; Syndergaard, S.

    The tropical deep convection affects the radiation balance of the atmosphere changing the water vapour mixing ratio and the temperature of the upper troposphere and lower stratosphere. To gain a better understanding of deep convective processes, the study of tropical cyclones could play an import...... (ACES) payload on the International Space Station....... 1194 profiles in a time window of 3 hours and a space window of 300 km from the eye of the cyclone. We show that the bending angle anomaly of a GPS RO signal is typically larger than the climatology above the tropopause. Comparisons with co-located radiosondes, climatology of tropopause altitudes...... and GOES analyses will also be shown to support our hypothesis and to corroborate the idea that the bending angle anomaly can be used as an indicator of convective towers. The results are discussed in connection to the GPS radio occultation receiver which will be part of the Atomic Clock Ensemble in Space...

  9. What can the occult do for you?

    Science.gov (United States)

    Holwerda, B. W.; Keel, W. C.

    2017-03-01

    Interstellar dust is still a dominant uncertainty in Astronomy, limiting precision in e.g., cosmological distance estimates and models of how light is re-processed within a galaxy. When a foreground galaxy serendipitously overlaps a more distant one, the latter backlights the dusty structures in the nearer foreground galaxy. Such an overlapping or occulting galaxy pair can be used to measure the distribution of dust in the closest galaxy with great accuracy. The STARSMOG program uses Hubble to map the distribution of dust in foreground galaxies in fine (<100 pc) detail. Integral Field Unit (IFU) observations will map the effective extinction curve, disentangling the role of fine-scale geometry and grain composition on the path of light through a galaxy. The overlapping galaxy technique promises to deliver a clear understanding of the dust in galaxies: geometry, a probability function of dimming as a function of galaxy mass and radius, and its dependence on wavelength.

  10. Occult hepatitis B virus infection in Egypt

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    The emerging evidence of the potentially clinicalimportance of occult hepatitis B virus (HBV) infection(OBI) increases the interest in this topic. OBI mayimpact in several clinical contexts, which include thepossible transmission of the infection, the contributionto liver disease progression, the development ofhepatocellular carcinoma, and the risk of reactivation.There are several articles that have published on OBI inEgyptian populations. A review of MEDLINE databasewas undertaken for relevant articles to clarify theepidemiology of OBI in Egypt. HBV genotype D is theonly detectable genotype among Egyptian OBI patients.Higher rates of OBI reported among Egyptian chronicHCV, hemodialysis, children with malignant disorders, andcryptogenic liver disease patients. There is an evidenceof OBI reactivation after treatment with chemotherapy.The available data suggested that screening for OBI mustbe a routine practice in these groups of patients. Furtherstudies needed for better understand of the epidemiologyof OBI among Egyptian young generations after the eraof hepatitis B vaccination.

  11. What can the occult do for you?

    CERN Document Server

    Holwerda, B W

    2016-01-01

    Interstellar dust is still a dominant uncertainty in Astronomy, limiting precision in e.g., cosmological distance estimates and models of how light is re-processed within a galaxy. When a foreground galaxy serendipitously overlaps a more distant one, the latter backlights the dusty structures in the nearer foreground galaxy. Such an overlapping or occulting galaxy pair can be used to measure the distribution of dust in the closest galaxy with great accuracy. The STARSMOG program uses Hubble to map the distribution of dust in foreground galaxies in fine (<100 pc) detail. Integral Field Unit (IFU) observations will map the effective extinction curve, disentangling the role of fine-scale geometry and grain composition on the path of light through a galaxy. The overlapping galaxy technique promises to deliver a clear understanding of the dust in galaxies: geometry, a probability function of dimming as a function of galaxy mass and radius, and its dependence on wavelength.

  12. Theory of radio occultation by Saturn's rings

    Science.gov (United States)

    Marouf, E. A.; Tyler, G. L.; Eshleman, V. R.

    1982-01-01

    The radio occultation technique, as applied to Saturn's rings, is developed as a new method for the study of the physical properties of planetary ring systems. The rings are treated as a Doppler-spread radar target composed of an ensemble of discrete scatterers. The mathematical formulation of the received signal as a random-phasor-sum process is carried out following a conventional radar theory approach, providing a convenient starting point for deriving coherent signal parameters. A classical result is rederived for the equivalent refractive index of the medium. The analysis is generalized to include ringlets of arbitrary width and it is shown that when the width is such that two adjacent rays are differentially perturbed in phase, ray bending that causes focusing of the coherent signal may result. The diffuse component is also treated in detail.

  13. Decomposition method for zonal resource allocation problems in telecommunication networks

    Science.gov (United States)

    Konnov, I. V.; Kashuba, A. Yu

    2016-11-01

    We consider problems of optimal resource allocation in telecommunication networks. We first give an optimization formulation for the case where the network manager aims to distribute some homogeneous resource (bandwidth) among users of one region with quadratic charge and fee functions and present simple and efficient solution methods. Next, we consider a more general problem for a provider of a wireless communication network divided into zones (clusters) with common capacity constraints. We obtain a convex quadratic optimization problem involving capacity and balance constraints. By using the dual Lagrangian method with respect to the capacity constraint, we suggest to reduce the initial problem to a single-dimensional optimization problem, but calculation of the cost function value leads to independent solution of zonal problems, which coincide with the above single region problem. Some results of computational experiments confirm the applicability of the new methods.

  14. Computing rare transitions between zonal mid-latitude jets

    Science.gov (United States)

    Simonnet, Eric; Bouchet, Freddy

    2016-04-01

    Zonal jets are known to naturally emerge from beta-plane turbulence due to the arrest of inverse energy cascade by Rossby waves.Transitions between jets of different wavenumber are indeed observed in particular regimes showing a striking example of bimodality in the context of 2-D turbulence. As the Rayleigh dissipation and stochastic forcing are decreased these transitions become more and more rare. The aim of this talk is to show that it is possible to compute large ensembles of reactive trajectories connecting the different metastable states even at very low probability regimes when direct numerical simulations are not possible. We use an adaptive version of multilevel splitting algorithms on a barotropic quasi geostrophic model of mid-latitude atmosphere. We are able to obtain a detailed statistical description of the high-dimensional phase space as well as the typical transitions. A large-deviation result is also obtained.

  15. Recognition of Historical Records Using Gabor and Zonal Features

    Directory of Open Access Journals (Sweden)

    Soumya A

    2015-08-01

    Full Text Available The paper addresses the automation of the task of an epigraphist in reading and deciphering inscriptions. The automation steps include Pre-processing, Segmentation, Feature Extraction and Recognition. Preprocessing involves, enhancement of degraded ancient document images which is achieved through Spatial filtering methods, followed by binarization of the enhanced image. Segmentation is carried out using Drop Fall and Water Reservoir approaches, to obtain sampled characters. Next Gabor and Zonal features are extracted for the sampled characters, and stored as feature vectors for training. Artificial Neural Network (ANN is trained with these feature vectors and later used for classification of new test characters. Finally the classified characters are mapped to characters of modern form. The system showed good results when tested on the nearly 150 samples of ancient Kannada epigraphs from Ashoka and Hoysala periods. An average Recognition accuracy of 80.2% for Ashoka period and 75.6% for Hoysala period is achieved.

  16. SPI Conformance Gel Applications in Geothermal Zonal Isolation

    Energy Technology Data Exchange (ETDEWEB)

    Burns, Lyle [Clean Tech Innovations, Bartlesville, OK (United States)

    2017-08-08

    Zonal isolation in geothermal injection and producing wells is important while drilling the wells when highly fractured geothermal zones are encountered and there is a need to keep the fluids from interfering with the drilling operation. Department of Energy’s (DOE) Energy Efficiency and Renewable Energy (EERE) objectives are to advance technologies to make it more cost effective to develop, produce, and monitor geothermal reservoirs and produce geothermal energy. Thus, zonal isolation is critical to well cost, reservoir evaluation and operations. Traditional cementing off of the lost circulation or thief zones during drilling is often done to stem the drilling mud losses. This is an expensive and generally unsuccessful technique losing the potential of the remaining fracture system. Selective placement of strong SPI gels into only the offending fractures can maintain and even improve operational efficiency and resource life. The SPI gel system is a unique silicate based gel system that offers a promising solution to thief zones and conformance problems with water and CO2 floods and potentially geothermal operations. This gel system remains a low viscosity fluid until an initiator (either internal such as an additive or external such as CO2) triggers gelation. This is a clear improvement over current mechanical methods of using packers, plugs, liners and cementing technologies that often severely damage the highly fractured area that is isolated. In the SPI gels, the initiator sets up the fluid into a water-like (not a precipitate) gel and when the isolated zone needs to be reopened, the SPI gel may be removed with an alkaline solution without formation damage occurring. In addition, the SPI gel in commercial quantities is expected to be less expensive than competing mechanical systems and has unique deep placement possibilities. This project seeks to improve upon the SPI gel integrity by modifying the various components to impart temperature stability for use in

  17. Effect of scalar nonlinearity on zonal flow generation by Rossby waves

    NARCIS (Netherlands)

    Mikhailovskii, A. B.; Lominadze, J. G.; Erokhin, N. N.; Erokhin, N. S.; Smolyakov, A. I.; Tsypin, V. S.

    2007-01-01

    Effects of scalar nonlinearity on the generation of zonal flow by Rossby waves in shallow rotating fluid are considered. Zonal flows are generated via the action of Reynolds stress due to vector nonlinearity together with the effects of scalar nonlinearity. It is shown that the scalar nonlinearity r

  18. Zonal flow dynamics in the double tearing mode with antisymmetric shear flows

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Aohua [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Graduate School of Energy Science, Kyoto University, Uji, Kyoto 6110011 (Japan); Li, Jiquan, E-mail: lijq@energy.kyoto-u.ac.jp [Graduate School of Energy Science, Kyoto University, Uji, Kyoto 6110011 (Japan); Liu, Jinyuan, E-mail: jyliu@dlut.edu.cn [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Kishimoto, Yasuaki [Graduate School of Energy Science, Kyoto University, Uji, Kyoto 6110011 (Japan); Institude of Advanced Energy, Kyoto University, Uji, Kyoto 6110011 (Japan)

    2014-05-15

    The generation dynamics and the structural characteristics of zonal flows are investigated in the double tearing mode (DTM) with antisymmetric shear flows. Two kinds of zonal flow oscillations are revealed based on reduced resistive magnetohydrodynamics simulations, which depend on the shear flow amplitudes corresponding to different DTM eigen mode states, elaborated by Mao et al. [Phys. Plasmas 20, 022114 (2013)]. For the weak shear flows below an amplitude threshold, v{sub c}, at which two DTM eigen states with antisymmetric or symmetric magnetic island structure are degenerated, the zonal flows grow oscillatorily in the Rutherford regime during the nonlinear evolution of the DTMs. It is identified that the oscillation mechanism results from the nonlinear interaction between the distorted islands and the zonal flows through the modification of shear flows. However, for the medium shear flows above v{sub c} but below the critical threshold of the Kelvin-Helmholtz instability, an oscillatory growing zonal flow occurs in the linear phase of the DTM evolution. It is demonstrated that the zonal flow oscillation originates from the three-wave mode coupling or a modulation instability pumped by two DTM eigen modes with the same frequency but opposite propagating direction. With the shear flows increasing, the amplitude of zonal flow oscillation increases first and then decreases, whilst the oscillation frequency as twice of the Doppler frequency shift increases. Furthermore, impacts of the oscillatory zonal flows on the nonlinear evolution of DTM islands and the global reconnection are also discussed briefly.

  19. Comparative study on the clinical and virological characteristics among patients with single occult hepatitis B virus (HBV), single occult hepatitis C virus (HCV) and occult HBV and HCV dual infection.

    Science.gov (United States)

    Castillo, Inmaculada; Rodríguez-Iñigo, Elena; López-Alcorocho, Juan Manuel; Bartolomé, Javier; Pardo, Margarita; Carreño, Vicente

    2007-03-01

    Occult hepatitis B virus (HBV) and occult hepatitis C virus (HCV) infection are two recently described different forms of HBV and HCV infections. This work compares the clinical, virologic, and histologic characteristics of patients with occult dual infection to those of patients with single occult HBV or HCV infection. Seventy-six patients with abnormal liver function tests of unknown etiology (serum HBsAg, anti-HCV, HBV-DNA, and HCV-RNA negative) were included in the study. Viral genomes were tested in liver by real-time PCR and confirmed by in situ hybridization. Of the 76 patients, 17 had occult HBV infection (intrahepatic HBV-DNA positive, HCV-RNA negative), 35 had occult HCV infection (intrahepatic HCV-RNA positive, HBV-DNA negative) and 24 occult dual infection (intrahepatic HCV-RNA and HBV-DNA). No differences among the three groups were found regarding clinical and epidemiologic data. The median load of intrahepatic genomic and antigenomic HCV-RNA strands was similar between single occult HCV infection and occult HBV and HCV dual infection. The percentage of HCV-infected hepatocytes did not differ between these groups. In occult single HBV infection, intrahepatic levels of HBV-DNA and percentage of HBV-infected hepatocytes were similar to the group of patients with occult dual infection. Finally, no differences were found in histological liver damage among the three groups. In conclusion, liver disease in patients with occult dual infection was not more severe than in patients with single occult HBV or occult HCV infection. Moreover, in occult dual infection there is no a reciprocal inhibition of the viral genomes.

  20. Fecal Occult Blood Test and Fecal Immunochemical Test

    Science.gov (United States)

    ... Visit Global Sites Search Help? Fecal Occult Blood Test and Fecal Immunochemical Test Share this page: Was this page helpful? Also ... Test Common Questions Ask Us Related Pages The Test How is it used? When is it ordered? ...

  1. Solar occultation with SCIAMACHY: algorithm description and first validation

    Directory of Open Access Journals (Sweden)

    J. Meyer

    2005-01-01

    Full Text Available This presentation concentrates on solar occultation measurements with the spaceborne spectrometer SCIAMACHY in the UV-Vis wavelength range. Solar occultation measurements provide unique information about the vertical distribution of atmospheric constituents. For retrieval of vertical trace gas concentration profiles, an algorithm has been developed based on the optimal estimation method. The forward model is capable of simulating the extinction signals of different species as they occur in atmospheric transmission spectra obtained from occultation measurements. Furthermore, correction algorithms have been implemented to address shortcomings of the tangent height pre-processing and inhomogeneities of measured solar spectra. First results of O3 and NO2 vertical profile retrievals have been validated with data from ozone sondes and satellite based occultation instruments. The validation shows very promising results for SCIAMACHY O3 and NO2 values between 15 to 35km with errors of the order of 10% and 15%, respectively.

  2. An Outrigger Component for a Deployable Occulter System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In Phase II, Roccor proposes to build upon the results of Phase I to increase the technology readiness level (TRL) of the NASA JPL deployable external occulter. An...

  3. Ambulatory Pessary Trial Unmasks Occult Stress Urinary Incontinence

    Directory of Open Access Journals (Sweden)

    Bilal Chughtai

    2012-01-01

    Conclusion. An ambulatory pessary trial is an effective, easy, and inexpensive method to approximate anatomic results achieved by surgery under real-life conditions. In our series, 20% of patients with occult SUI were identified by pessary trial alone.

  4. UARS Halogen Occultation Experiment (HALOE) Level 2 V001

    Data.gov (United States)

    National Aeronautics and Space Administration — The HALOE home page on the WWW is http://haloe.gats-inc.com/home/index.php The Halogen Occultation Experiment (HALOE) on NASA's Upper Atmosphere Research Satellite...

  5. Radio occultation based on BeiDou satellite navigation

    Science.gov (United States)

    Jiang, Hu; Hu, Haiying; Shen, Xue-min; Gong, Wenbin; Zhang, Yonghe

    2014-11-01

    With the development of GNSS systems, it has become a tendency that radio occultation is used to sense the Earth's atmosphere. By this means, the moisture, temperature, pressure, and total electron content can be derived. Based on the sensing results, more complicated models for atmosphere might come into being. Meteorology well benefits from this technology. As scheduled, the BD satellite navigation system will have a worldwide coverage by the end of 2020. Radio occultation studies in China have been highlighted in the recent decade. More and more feasibilities reports have been published in either domestic or international journals. Herein, some scenarios are proposed to assess the coverage of radio occultation based on two different phases of BD satellite navigation system. Phase one for BD is composed of GEO,IGSO and several MEO satellites. Phase two for BD consists mostly of 24 MEO satellites, some GEO and IGSO satellites. The characteristics of radio occultation based on these two phases are presented respectively.

  6. Research on Zonal Inspection Intervals of Civil Aircraft Based on Improved FAHP

    Directory of Open Access Journals (Sweden)

    Lu Xiang

    2013-07-01

    Full Text Available One of the most important things in formulating aircraft maintenance program is to determine the zonal inspection intervals. In accordance with the current situation that there has no perfect rating systems of zonal inspection under MSG-3 (Maintenance Steering Group-3 analysis system, a method to calculate the integrate level of zonal rating is to analyze the impact of aircraft zonal rating factors, establish a hierarchical index evaluation system and then utilize the improved fuzzy analytic hierarchy process (FAHP to determine the indexes’ weight. Moreover, the zonal inspection intervals can be established according to the correspondence between rates and intervals. Finally, take a typical zone of an aircraft as an example to verify the method.  

  7. Occult hepatitis B among Iranian hepatitis C patients

    OpenAIRE

    Ahmad shavakhi; Babak Norinaier; Fatomeh Esteghamat; Mohamad Seghatoleslami; Mahsa Khodadustan; Mohamad hossein Somi; Mohsen Masoodi; Mohamad reza Zali

    2009-01-01

    • BACKGROUND: Occult hepatitis B is defined as presence of HBV DNA in tissue or serum without hepatitis B surface antigen. The aim of this study is to determine frequency of occult hepatitis B among hepatitis C patients in Tehran and compare the route of transmission and liver enzymes between positive and negative HBV DNA patients.
    • METHODS: In a cross sectional study, serum of 103 hepatitis C cas...

    • New perspectives in occult hepatitis C virus infection

      OpenAIRE

      CARREÑO, VICENTE; Bartolomé, Javier; Castillo, Inmaculada; Quiroga, Juan Antonio

      2012-01-01

      Occult hepatitis C virus (HCV) infection, defined as the presence of HCV RNA in liver and in peripheral blood mononuclear cells (PBMCs) in the absence of detectable viral RNA in serum by standard assays, can be found in anti-HCV positive patients with normal serum levels of liver enzymes and in anti-HCV negative patients with persistently elevated liver enzymes of unknown etiology. Occult HCV infection is distributed worldwide and all HCV genotypes seem to be involved in this infection. Occul...

    • A Sign of Occult Spinal Dysraphism: Faun Tail

      OpenAIRE

      Canpolat, Filiz; AKPINAR, Hatice; B?LG?Ç, Özlem; ESK?O?LU, Fatma

      2015-01-01

      Spinal dysraphism refers to incomplete fusion of midline structures of the embriyonal dorsal median region. Tethered cord is one of the markers of occult spinal dysraphism. Cutaneous changes of spinal dysraphism may include a lipoma, dermal sinus/cyst, hypertrichosis, dimple, hyperpigmentation, capillary hemangioma and aplasia cutis. These signs led to early recognution of the occult neurological abnormalities. Magnetic resonance imaging is considered to be the gold standard for investigating...

    • Sensitivity of GPS occultation to the stratopause height

      DEFF Research Database (Denmark)

      Schrøder, Thomas Morville; Ao, Chi; de la Torre Juárez, Manuel

      2007-01-01

      We scrutinize temperature profiles collected with radio occultation measurement for an imprint of the stratopause. In the retrieval step that integrates bending angle data to atmospheric refractivity, the falloff toward infinite altitude is constrained in a boundary condition with statistical...... rate, not isothermal conditions. Keeping the model seed for temperature conversion to subsequent retrieval steps eliminates external information from the deconvolved refractivity. It will help argue for radio occultation as independent vehicle for climate monitoring....

    • Status of the Transneptunian Automated Occultation Survey (TAOS II)

      Science.gov (United States)

      Lehner, Matthew; Wang, Shiang-Yu; Alcock, Charles; Reyes-Ruiz, Mauricio; Castro, Joel; Chen, Wen Ping; Chu, You-Hua; Cook, Kem H.; Geary, John C.; Huang, Chung-Kai; Kim, Dae-Won; Norton, Timothy; Szentgyorgyi, Andrew; Yen, WeiLing; Zhang, Zhi-Wei; Figueroa, Liliana

      2016-10-01

      The Transneptunian Automated Occultation Survey (TAOS II) will aim to detect occultations of stars by small (~1 km diameter) objects in the Kuiper Belt and beyond. Such events are very rare ($Construction of the site began in the fall of 2013, and the survey will begin in the summer of 2017. This poster will provide an update on the status of the survey development and the schedule leading to the beginning of survey operations.

    • Occult hepatitis C virus infection among hemodialysis patients.

      Science.gov (United States)

      Barril, Guillermina; Castillo, Inmaculada; Arenas, María Dolores; Espinosa, Mario; Garcia-Valdecasas, Juan; Garcia-Fernández, Nuria; González-Parra, Emilio; Alcazar, José María; Sánchez, Carmen; Diez-Baylón, José Carlos; Martinez, Pilar; Bartolomé, Javier; Carreño, Vicente

      2008-12-01

      Occult hepatitis C virus (HCV) infection (i.e., detectable HCV-RNA in the liver or peripheral blood mononuclear cells) in the absence of both serum HCV-RNA and anti-HCV antibodies has not been investigated in hemodialysis patients. In this study, real-time PCR and in situ hybridization was used to test for the presence of genomic and antigenomic HCV-RNA in peripheral blood mononuclear cells of 109 hemodialysis patients with abnormal levels of liver enzymes. Occult HCV infection, determined by the presence of genomic HCV-RNA, was found in 45% of the patients; 53% of these patients had ongoing HCV replication, indicated by the presence of antigenomic HCV-RNA. Patients with occult HCV infection had spent a significantly longer time on hemodialysis and had significantly higher mean alanine aminotransferase levels during the 6 mo before study entry. Logistic regression analysis revealed that mortality was associated with age >60 yr (odds ratio 3.30; 95% confidence interval 1.05 to 10.33) and the presence of occult HCV infection (odds ratio 3.84; 95% confidence interval 1.29 to 11.43). In conclusion, the prevalence of occult HCV infection is high among hemodialysis patients with persistently abnormal values of liver enzymes of unknown cause. The clinical significance of occult HCV infection in these patients requires further study.

    • Occult HBV infection among Egyptian hepatocellular carcinoma patients

      Directory of Open Access Journals (Sweden)

      Mansor Tarek M

      2011-03-01

      Full Text Available Abstract Background Occult HBV infection accelerates the progression of liver fibrosis, cirrhosis, and finally leading to hepatocellular carcinoma (HCC. This study analyzed the occult HBV-genotypes in HCC patients. Methods To achieve our objective, matched serum and tissue samples were collected from 40 HCC patients. Three sets of primers were used for the HBV-DNA detection by nested-PCR, which cover the HBV-genome; Core, Surface and X genes. Genotyping system based on PCR using type-specific primers was applied on HBV-DNA positive samples. Results Intrahepatic occult HBV-DNA was detected in 62.5%, whereas; Serum occult HBV-DNA were detected in only 22.5% of HCC patients. In patients' positive for both anti-HBs and anti-HBc, 10% had occult HBV in serum. In serologically negative HCV patients, 63% had intrahepatic HBV-DNA, and 21% had HBV-DNA in serum samples. HBV-genotype D (32% and B (24% attributed predominantly to intrahepatic HBV infections in HCC patients, whereas HBV-genotype A (4% and C (8% infections were the least observed. Conclusion This is the first study to show the genotypes of occult HBV infection in HCC Patients. We suggest that B or D may influence the outcome of HBV infection which may lead to the development of HCC.

    • Diagnostic strategy for occult hepatitis B virus infection

      Institute of Scientific and Technical Information of China (English)

      Sara Ocana; Maria Luisa Casas; Ingrid Buhigas; Jose Luis Lledo

      2011-01-01

      In 2008, the European Association for the study of the liver (EASL) defined occult hepatitis B virus infection (OBI) as the "presence of hepatitis B virus (HBV) DNA in the liver (with detectable or undetectable HBV DNA in the serum) of individuals testing hepatitis B surface antigen (HBsAg) negative by currently available assays". Several aspects of occult HBV infection are still poorly understood, including the definition itself and a standardized approach for laboratory-based detection, which is the purpose of this review. The clinical significance of OBI has not yet been established; however, in terms of public health, the clinical importance arises from the risk of HBV transmission. Consequently, it is important to detect high-risk groups for occult HBV infection to prevent transmission. The main issue is, perhaps, to identify the target population for screening OBI. Viremia is very low or undetectable in occult HBV infection, even when the most sensitive methods are used, and the detection of the viral DNA reservoir in hepatocytes would provide the best evaluation of occult HBV prevalence in a defined set of patients. However, this diagnostic approach is obviously unsuitable: blood detection of occult hepatitis B requires assays of the highest sensitivity and specificity with a lower limit of detection < 10 IU/mL for HBV DNA and < 0.1 ng/mL for HBsAg.

    • Earth Occultation Monitoring with the Fermi Gamma Ray Burst Monitor

      Science.gov (United States)

      Wilson-Hodge, Colleen A.

      2014-01-01

      Using the Gamma Ray Burst Monitor (GBM) on-board Fermi, we are monitoring the hard X-ray/soft gamma ray sky using the Earth occultation technique (EOT). Each time a source in our catalog is occulted by (or exits occultation by) the Earth, we measure its flux using the change in count rates due to the occultation. Currently we are using CTIME data with 8 energy channels spanning 8 keV to 1 MeV for the GBM NaI detectors for daily monitoring. Light curves, updated daily, are available on our website http://heastro.phys.lsu.edu/gbm. Our software is also capable of performing the Earth occultation monitoring using up to 128 energy bands, or any combination of those bands, using our 128-channel, 4-s CSPEC data. The GBM BGO detectors, sensitive from about 200 keV to 40 keV, can also be used with this technique. In our standard application of the EOT, we use a catalog of sources to drive the measurements. To ensure that our catalog is complete, our team has developed an Earth occultation imaging method. In this talk, I will describe both techniques and the current data products available. I will highlight recent and important results from the GBM EOT, including the current status of our observations of hard X-ray variations in the Crab Nebula.

    • The Return of Congenital Rickets, Are We Missing Occult Cases?

      Science.gov (United States)

      Elidrissy, Abdelwahab T H

      2016-09-01

      Congenital rickets is the term given to fetus born with clinical features of rickets, but those born with biochemical evidence of rickets without obvious clinical features still can be considered occult congenital rickets. Some of the affected babies with this disease have the intrauterine rachitic environment, but a calcium trans-placental pump prevents the fetus from having clinical features of rickets. They may present with hypocalcemia few days after birth or later with more florid features of rickets. Congenital rickets cases born with florid features reported over the last 40 years are few and can be divided into two groups. The first due to severe maternal osteomalacia in which their bones were so decalcified to have enough calcium to be pumped to their fetus. Another group in which newborn babies were hypocalcemic due to other maternal diseases as malabsorption, celiac disease, pre-eclampsia, and prematurity. All inherited rickets cases per se, or as part of other syndromes can be considered congenital rickets. Most cases seen in our region are due to maternal vitamin D deficiency with symptoms becoming obvious when the infants are breastfed, or may present with hypocalcemic convulsions or craniotabes. This is a review of congenital rickets with the aim of shedding light on this potentially acute disease that needs more attention and awareness in the neonatal period to avoid rare serious complications as cardiomyopathy or myelofibrosis and the complications of hypocalcemic convulsions. Congenital rickets cases seen simulate a tip of an ice-burg and its prevention is an important issue, especially with the tremendous urbanization with tall buildings living in sun-deprived flats as the commonest type of residence leading to the increasing incidence of maternal osteomalacia and rickets.

    • Clues to occult cancer in patients with ischemic stroke.

      Directory of Open Access Journals (Sweden)

      Suk Jae Kim

      Full Text Available BACKGROUND: We hypothesized that hidden malignancy could be detected in patients with cryptogenic stroke without active cancer when they showed the distinctive characteristics of cancer-related stroke. METHODS AND FINDINGS: Among 2,562 consecutive patients with acute ischemic stroke, patients with cryptogenic stroke were analyzed and categorized into two groups according to the presence of active cancer: cryptogenic stroke with active cancer (cancer-related stroke, CA-stroke group and without active cancer (CR-stroke group. Patients with active lung cancer without stroke were also recruited for comparison purposes (CA-control. Clinical factors, lesion patterns on diffusion-weighted MRI (DWI, and laboratory findings were analyzed among groups. A total of 348 patients with cryptogenic stroke were enrolled in this study. Among them, 71 (20.4% patients had active cancer at the time of stroke. The D-dimer levels were significantly higher in patients with CA-stroke than those with CR-stroke or CA-control (both p<0.001. Regarding lesion patterns, patients with CA-stroke mostly had multiple lesions in multiple vascular territories, while more than 80% of patients with CR-stroke had single/multiple lesions in a single vascular territory (P<0.001. D-dimer levels (OR 1.11 per 1 µg/mL increase; 95% CI 1.06-1.15; P<0.001 and DWI lesion patterns (OR 7.13; 95% CI 3.42-14.87; P<0.001 were independently associated with CA-stroke. Workup for hidden malignancy was performed during hospitalization in 10 patients who showed elevated D-dimer levels and multiple infarcts involving multiple vascular territories but had no known cancer, and it revealed hidden malignancies in all the patients. CONCLUSION: Patients with CA-stroke have distinctive D-dimer levels and lesion patterns. These characteristics can serve as clues to occult cancer in patients with cryptogenic stroke.

    • NOAA Climate Data Record (CDR) of Zonal Mean Ozone Binary Database of Profiles (BDBP), version 1.0

      Data.gov (United States)

      National Oceanic and Atmospheric Administration, Department of Commerce — This NOAA Climate Data Record (CDR) of Zonal Mean Ozone Binary Database of Profiles (BDBP) dataset is a vertically resolved, global, gap-free and zonal mean dataset...

    • Recent pollen spectra and zonal vegetation in the western USSR

      Science.gov (United States)

      Peterson, G. M.

      The relationship of modern pollen spectra to present-day vegetation is critical to the reconstruction of vegetation and climate from fossil pollen spectra. This study uses isopoll maps to illustrate the pollen-vegetation relationships in the Soviet Union west of 100°E and presents descriptive statistics for 544 modern samples of arboreal pollen and for 370 samples of herb pollen obtained from the Soviet palynological literature. Data are assembled from this large geographic region and presented in a standardized form on a scale which can be used to relate quantitative pollen data to zonal vegetation and climatic variables and to make comparisons with other regions. In order to show the relationship between pollen types and major ecotones in forested and non-forested areas, the pollen data are presented as percentages of a sum including both arboreal and non-arboreal pollen. Major pollen types which attain values of 10% or more in at least one vegetation zone include Betula (birch), Cyperaceae (sedges), Picea (spruce), Pinus (total pine), Pinus sibirica, Ericaceae (heath family), Gramineae (grasses), Artemisia (sage), and Chenopodiaceae (i.e., saltbush, Russian thistle, pigweed family). Samples from the tundra and forest-tundra have high values of Ericaceae (heath family), birch, alder, and sedge pollen. In the boreal forest, pine, spruce, and birch pollen predominate. In the mixed and deciduous forests, Tilia (linden), Quercus (oak), Ulmus (elm), and Corylus (hazel) pollen attain maximum values. In the forest-steppe and steppe zones, arboreal pollen decreases in importance and is replaced by non-arboreal pollen types. Pollen of Artemisia and Chenopodiaceae predominates in the semi-desert zones. In spite of variation in the pollen spectra arising from the use of different sediment types (soil, peat, and river sediments), and human disturbance of vegetation, the pollen spectra are clearly related to zonal vegetation. Pollen spectra from the western USSR show

    • The zonal motion of equatorial plasma bubbles relative to the background ionosphere

      Science.gov (United States)

      Kil, Hyosub; Lee, Woo Kyoung; Kwak, Young-Sil; Zhang, Yongliang; Paxton, Larry J.; Milla, Marco

      2014-07-01

      The zonal motions of plasmas inside equatorial plasma bubbles are different from those in the background ionosphere. The difference was explained in terms of the tilt of bubbles by recent studies, but observational evidence of this hypothesis has not yet been provided. We examine this hypothesis and, at the same time, look for an alternative explanation on the basis of the coincident satellite and radar observations over Jicamarca (11.95°S, 76.87°W) in Peru. In the observations at premidnight by the first Republic of China satellite (altitude: 600 km, inclination: 35°), plasmas inside bubbles drift westward relative to ambient plasmas. The same phenomenon is identified by radar observations. However, the relative westward plasma motions inside bubbles occur regardless of the tilt of bubbles, and therefore, the tilt is not the primary cause of the deviation of the plasma motions inside bubbles. The zonal plasma motions in the topside are characterized by systematic eastward drifts, whereas the zonal motions of plasmas in the bottomside backscatter layer show a mixture of eastward and westward drifts. The zonal plasma motions inside backscatter plumes resemble those in the bottomside backscatter layer. These observations indicate that plasmas inside bubbles maintain the properties of the zonal plasma motions in the bottomside where the bubbles originate. With this assumption, the deviation of the zonal motions of plasmas inside bubbles from those of ambient plasmas is understood in terms of the difference of the zonal plasma flows in the bottomside and topside.

  1. Visible and occult microscopic lesions of endometriosis

    Directory of Open Access Journals (Sweden)

    Khaleque Newaz Khan

    2014-11-01

    Full Text Available Endometriosis is a multifactorial disease mostly affecting women of reproductive age and is associated with chronic pelvic pain and infertility. Even after 300 years, most of the literature claims that pathogenesis and/or pathophysiology of endometriosis is still elusive. Recurrence of pain and lesion continues to occur after effective medical or surgical therapies. Once generated within the pelvis due to retrograde entry of menstrual debris, peritoneal endometriotic lesions time-dependently change their color appearance resulting from certain biochemical change within lesions. A variable pattern of endometriotic lesions within the pelvis can be detected by laparoscopy as visible peritoneal endometriosis. It is generally believed that besides ovarian steroid hormones, the growth of endometriosis can be regulated by the innate immune system in the pelvic microenvironment by their interaction with endometrial cells and immune cells. Even with the careful eyes of an expert surgeon, we may sometimes miss detecting peritoneal lesion within the peritoneal cavity or deep into the peritoneum. In such a case, random collection of normal peritoneum may carry the possibility to identify some hidden endometriotic lesions by microscopy and these lesions can be named as occult (invisible microscopic endometriosis (OME. Here, we discuss the color appearance of peritoneal lesions and activity of these lesions by analysis of a panel of activity markers. Finally we discuss our recent findings on OME, their biological and clinical significance, and try to make a possible link in the origin between visible endometriosis and OME.

  2. Occult celiac disease prevents penetrance of hemochromatosis

    Institute of Scientific and Technical Information of China (English)

    Andreas Geier; Siegfried Matern; Carsten Gartung; Igor Theurl; Guenter Weiss; Frank Lammert; Christoph G. Dietrich; Ralf Weiskirchen; Heinz Zoller; Benita Hermanns

    2005-01-01

    AIM: To report a patient with C282Y homozygocity, depleted body iron and intestinal atrophy caused by celiac disease (CD) who experienced resolution of the enteropathy with subsequent normalization of iron metabolism upon glutenfree diet.METHODS: To obtain information on the tissue distribution and quantitative expression of proteins involved in duodenal iron trafficking, we determined the expression of divalent-metal transporter 1 (DMT1), ferroportin 1 (FP1) and transferrin receptor (TfR1) by means of immunohistochemistry and real-time PCR in duodenal biopsies of this patient.RESULTS: Whereas in hereditary hemochromatosis patients without CD, DMT1 expression was up-regulated leading to excessive uptake of iron, we identified a significant reduction in protein and mRNA expression of DMT1 as acompensatory mechanism in this patient with HH and CD.CONCLUSION: Occult CD may compensate tot increased DMT1 expression in a specific subset of individuals withhomozygous C282Y mutations in the hemochromatosis(HFE) gene, thus contributing to the low penetrance of HH.

  3. Greater trochanteric fracture with occult intertrochanteric extension.

    Science.gov (United States)

    Reiter, Michael; O'Brien, Seth D; Bui-Mansfield, Liem T; Alderete, Joseph

    2013-10-01

    Proximal femoral fractures are frequently encountered in the emergency department (ED). Prompt diagnosis is paramount as delay will exacerbate the already poor outcomes associated with these injuries. In cases where radiography is negative but clinical suspicion remains high, magnetic resonance imaging (MRI) is the study of choice as it has the capability to depict fractures which are occult on other imaging modalities. Awareness of a particular subset of proximal femoral fractures, namely greater trochanteric fractures, is vital for both radiologists and clinicians since it has been well documented that they invariably have an intertrochanteric component which may require surgical management. The detection of intertrochanteric or cervical extension of greater trochanteric fractures has been described utilizing MRI but is underestimated with both computed tomography (CT) and bone scan. Therefore, if MRI is unavailable or contraindicated, the diagnosis of an isolated greater trochanteric fracture should be met with caution. The importance of avoiding this potential pitfall is demonstrated in the following case of an elderly woman with hip pain and CT demonstrating an isolated greater trochanteric fracture who subsequently returned to the ED with a displaced intertrochanteric fracture.

  4. Starshade Design for Occulter Based Exoplanet Missions

    Science.gov (United States)

    Thomson, Mark W.; Lisman, P. Douglas; Helms, Richard; Walkemeyer, Phil; Kissil, Andrew; Polanco, Otto; Lee, Siu-Chun

    2010-01-01

    We present a lightweight starshade design that delivers the requisite profile figure accuracy with a compact stowed volume that permits launching both the occulter system (starshade and spacecraft) and a 1 to 2m-class telescope system on a single existing launch vehicle. Optimal figure stability is achieved with a very stiff and mass-efficient deployable structure design that has a novel configuration. The reference design is matched to a 1.1m telescope and consists of a 15m diameter inner disc and 24 flower-like petals with 7.5m length. The total tip-to-tip diameter of 30m provides an inner working angle of 75 mas. The design is scalable to accommodate larger telescopes and several options have been assessed. A proof of concept petal is now in production at JPL for deployment demonstrations and as a testbed for developing additional elements of the design. Future plans include developing breadboard and prototype hardware of increasing fidelity for use in demonstrating critical performance capabilities such as deployed optical edge profile figure tolerances and stability thereof.

  5. Celestial shadows eclipses, transits, and occultations

    CERN Document Server

    Westfall, John

    2015-01-01

    Much of what is known about the universe comes from the study of celestial shadows—eclipses, transits, and occultations.  The most dramatic are total eclipses of the Sun, which constitute one of the most dramatic and awe-inspiring events of nature.  Though once a source of consternation or dread, solar eclipses now lead thousands of amateur astronomers and eclipse-chasers to travel to remote points on the globe to savor their beauty and the adrenaline-rush of experiencing totality, and were long the only source of information about the hauntingly beautiful chromosphere and corona of the Sun.   Long before Columbus, the curved shadow of the Earth on the Moon during a lunar eclipse revealed that we inhabit a round world. The rare and wonderful transits of Venus, which occur as it passes between the Earth and the Sun, inspired eighteenth century expeditions to measure the distance from the Earth to the Sun, while the recent transits of 2004 and 2012 were the most widely observed ever--and still produced re...

  6. Dynamics of Zonal Flows: Failure of Wave-Kinetic Theory, and New Geometrical Optics Approximations

    CERN Document Server

    Parker, Jeffrey B

    2016-01-01

    The self-organization of turbulence into regular zonal flows can be fruitfully investigated with quasilinear methods and statistical descriptions. A wave kinetic equation that assumes asymptotically large-scale zonal flows is pathological. From an exact description of quasilinear dynamics emerges two better geometrical optics approximations. These involve not only the mean flow shear but also the second and third derivative of the mean flow. One approximation takes the form of a new wave kinetic equation, but is only valid when the zonal flow is quasi-static and wave action is conserved.

  7. Zonal Flow as Pattern Formation: Merging Jets and the Ultimate Jet Length Scale

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey B. Parker and John A. Krommes

    2013-01-30

    Zonal flows are well known to arise spontaneously out of turbulence. It is shown that for statisti- cally averaged equations of quasigeostrophic turbulence on a beta plane, zonal flows and inhomoge- neous turbulence fit into the framework of pattern formation. There are many implications. First, the zonal flow wavelength is not unique. Indeed, in an idealized, infinite system, any wavelength within a certain continuous band corresponds to a solution. Second, of these wavelengths, only those within a smaller subband are linearly stable. Unstable wavelengths must evolve to reach a stable wavelength; this process manifests as merging jets.

  8. Observing upper troposphere-lower stratosphere climate with radio occultation data from the CHAMP satellite

    Energy Technology Data Exchange (ETDEWEB)

    Foelsche, Ulrich; Borsche, Michael; Steiner, Andrea K.; Gobiet, Andreas; Pirscher, Barbara; Kirchengast, Gottfried [University of Graz, Wegener Center for Climate and Global Change (WegCenter) and Institute for Geophysics, Astrophysics, and Meteorology (IGAM), Graz (Austria); Wickert, Jens; Schmidt, Torsten [GeoForschungsZentrum Potsdam (GFZ), Potsdam (Germany)

    2008-07-15

    High quality observations of the atmosphere are particularly required for monitoring global climate change. Radio occultation (RO) data, using Global Navigation Satellite System (GNSS) signals, are well suited for this challenge. The special climate utility of RO data arises from their long-term stability due to their self-calibrated nature. The German research satellite CHAllenging Minisatellite Payload for geoscientific research (CHAMP) continuously records RO profiles since August 2001 providing the first opportunity to create RO based climatologies for a multi-year period of more than 5 years. A period of missing CHAMP data from July 3, 2006 to August 8, 2006 can be bridged with RO data from the GRACE satellite (Gravity Recovery and Climate Experiment). We have built seasonal and zonal mean climatologies of atmospheric (dry) temperature, microwave refractivity, geopotential height and pressure with 10 latitudinal resolution. We show representative results with focus on dry temperatures and compare them with analysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF). Although we have available only about 150 CHAMP profiles per day (compared to millions of data entering the ECMWF analyses) the overall agreement between 8 and 30 km altitude is in general very good with systematic differences <0.5 K in most parts of the domain. Pronounced systematic differences (exceeding 2 K) in the tropical tropopause region and above Antarctica in southern winter can almost entirely be attributed to errors in the ECMWF analyses. Errors resulting from uneven sampling in space and time are a potential error source for single-satellite climatologies. The average CHAMP sampling error for seasonal zonal means is <0.2 K, higher values occur in restricted regions and time intervals which can be clearly identified by the sampling error estimation approach we introduced (which is based on ECMWF analysis fields). The total error of this new type of temperature

  9. Approach to acute, recurrent, and chronic pancreatitis.

    Science.gov (United States)

    Kinney, Timothy P; Freeman, Martin L

    2008-06-01

    Pancreatitis can manifest as a one-time episode, recurring attacks, or chronic pain. It is caused by numerous factors ranging from alcohol consumption to gallstones to subtle obstructive causes and occult autoimmune disorders. As a result, determining the etiology and effectively treating the causes and consequences of pancreatitis can be challenging. This article reviews the diagnosis and management of acute, acute recurrent, and chronic pancreatitis, focusing on more challenging scenarios.

  10. Distribution of the GNSS-LEO occultation events over Egypt

    Science.gov (United States)

    Ghoniem, Ibrahim; Mousa, Ashraf El-Kutb; El-Fiky, Gamal

    2017-06-01

    The space-based GNSS RO technique is a promising tool for monitoring the Earth's atmosphere and ionosphere (Mousa et al., 2006). The current paper presents the distribution of the occultation events over Egypt using the operating LEO satellites and GNSS by its two operating systems. By the present research, Egypt could raise NWP Models efficiency by improving meteorological data quality. Twenty operating LEO missions (e.g. Argentinean SAC-C, European MetOp-A, German TerraSAR-X, Indian OceanSat-2, etc.) sent by different countries all over the world were used to derive the occultation events position through Egypt borders by receiving signal from the American global positioning system (GPS) and the Russian global navigation satellite system (GLONASS). Approximately 20,000 km Altitude satellites are transmitting enormous number of rays by the day to approximately 800 km satellites passing by the Earth atmosphere. Our mission is to derive all of these rays position (start and end) by calculating satellites position by the time, determine the rays in the occultation case and derive the atmosphere tangent point position for all occultating rays on the Earth surface (Occultation Events).

  11. Pros and cons of screening for occult Cushing syndrome.

    Science.gov (United States)

    Tabarin, Antoine; Perez, Paul

    2011-03-22

    Systematic screening studies performed mainly in patients with diabetes mellitus have revealed an unexpectedly high prevalence of occult Cushing syndrome. Such studies may provide a rationale for systematically screening obese patients with type 2 diabetes mellitus. However, a screening strategy is only justified if it is supported by enough evidence of its efficacy and if the benefits will outweigh drawbacks. To date, the natural history of occult Cushing syndrome and its possible effect on long-term morbidity are unknown. The clinical spectrum of occult Cushing syndrome and its relatively low prevalence may potentially negatively affect the performance of endocrine tests used to diagnose overt Cushing syndrome and generate false positives. Whether the cure of occult Cushing syndrome favorably influences clinical outcomes and is more beneficial than treatment of diabetes mellitus and cardiovascular risk factors with currently available pharmacological tools remains to be demonstrated. Last, the acceptability of a screening program by professionals and the health-care system in terms of workload and costs is highly questionable. Thus, an assessment of the indications for and against screening for occult Cushing syndrome on the basis of currently available data suggests that, to date, the cons surpass the pros.

  12. [Occultism, parapsychology and the esoteric from the perspective of psychopathology].

    Science.gov (United States)

    Scharfetter, C

    1998-10-01

    The concepts and main themes of occultism, parapsychology and esoterics are set in comparison to religion, spirituality, mysticism. The cultural relativity of these concepts is emphasised. Occultism means dealing with phenomena, processes, and/or powers which are not accessible to "normal perception". The manipulation of such powers is effected via (white, black, grey) magic. Parapsychology, in its popular sense, deals with occult phenomena, whereas scientific parapsychology investigates them empirically. Esoterics is a complex of beliefs within a hermetic tradition about occult processes and about desting after death. Transpersonal psychology deals with these issues while calling them "spiritual". Effects of paranormal experiences and actions on the side of the actor as well as the adept are discussed: personality types, interpersonal effects, crises and psychoses (mediumistic psychoses). The concept of dissociation of subpersonalities (subselves) appears to be a viable perspective to explain these phenomena. In mediumistic psychoses, the splitting of non-ego parts of the psyche leads to a manifestation of schizophrenic symptoms. Dangers for mental health are an ego inflation by self-attribution of "superhuman" power. A personality disposition for parapsychological perception and/or action may be seen in schizotypia and similar near-psychotic "personalities up the border". Adepts of occultism may present with a "false self" in the sense of Winnicott.

  13. The Lunar Occultation Observer (LOCO) -- A Nuclear Astrophysics All-Sky Survey Mission Concept

    Science.gov (United States)

    Miller, R. S.; Bonamente, M.; Burgess, J. M.; Jenke, P.; Lawrence, D. J.; O'Brien, S.; Orr, M. R.; Paciesas, W. S.; Young, C. A.

    2009-03-01

    The Lunar Occultation Observer (LOCO) is a new γ-ray astrophysics mission concept expected to have unprecedented sensitivity in the nuclear regime. Operating in lunar orbit, LOCO will utilize lunar occultation imaging to survey and probe the cosmos.

  14. Stationary Zonal Flows during the Formation of the Edge Transport Barrier in the JET Tokamak.

    Science.gov (United States)

    Hillesheim, J C; Delabie, E; Meyer, H; Maggi, C F; Meneses, L; Poli, E; Jet Contributors

    2016-02-12

    High spatial resolution Doppler backscattering measurements in JET have enabled new insights into the development of the edge Er. We observe fine-scale spatial structures in the edge Er well with a wave number krρi≈0.4-0.8, consistent with stationary zonal flows, the characteristics of which vary with density. The zonal flow amplitude and wavelength both decrease with local collisionality, such that the zonal flow E×B shear increases. Above the minimum of the L-H transition power threshold dependence on density, the zonal flows are present during L mode and disappear following the H-mode transition, while below the minimum they are reduced below measurable amplitude during L mode, before the L-H transition.

  15. Wind Diffusivity Current, METOP ASCAT, 0.25 degrees, Global, Near Real Time, Zonal

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes near real time Ekman current (in zonal, meridional, and modulus sets) and Ekman upwelling data. This data begins with wind velocity...

  16. Changes in zonal surface temperature gradients and Walker circulations in a wide range of climates

    CERN Document Server

    Merlis, Timothy M

    2010-01-01

    Variations in zonal surface temperature gradients and zonally asymmetric tropical overturning circulations (Walker circulations) are examined over a wide range of climates simulated with an idealized atmospheric general circulation model (GCM). The asymmetry in the tropical climate is generated by an imposed ocean energy flux, which does not vary with climate. The range of climates is simulated by modifying the optical thickness of an idealized longwave absorber (representing greenhouse gases). The zonal surface temperature gradient in low latitudes generally decreases as the climate warms in the idealized GCM simulations. A scaling relationship based on a two-term balance in the surface energy budget accounts for the changes in the zonally asymmetric component of the GCM-simulated surface temperature gradients. As in comprehensive simulations of climate change, the Walker circulation weakens as the climate warms in the idealized simulations. The wide range of climates allows a systematic test of energetic ar...

  17. HIRDLS/Aura Level 3 Chlorofluorocarbon-11 (CFC-11) Zonal Fourier Coefficients V007

    Data.gov (United States)

    National Aeronautics and Space Administration — The "HIRDLS/Aura Level 3 Chlorofluorocarbon-11 (CFC-11) Zonal Fourier Coefficients" version 7 data product (H3ZFCCFC11) contains the entire mission (~3 years) of...

  18. Wind Stress, METOP ASCAT, 0.25 degrees, Global, Near Real Time, Zonal

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes near real time wind stress data in zonal, meridional, modulus, and wind stress curl sets. This data begins with wind velocity...

  19. Wind Stress, QuikSCAT SeaWinds, 0.25 degrees, Global, Science Quality, Zonal

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes science quality wind stress data in zonal, meridional, modulus, and wind stress curl sets. This data begins with wind velocity...

  20. Currents, HF Radio-derived, SF Bay, 1 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 1 hour average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN EXPERIMENTAL...

  1. Currents, HF Radio-derived, SF Bay Outlet, 1 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 1 hour average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN EXPERIMENTAL...

  2. Currents, HF Radio-derived, SF Bay Outlet, 25 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 25 hour running average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN...

  3. TOMS/EP UV Aerosol Index Daily and Monthly Zonal Means V008

    Data.gov (United States)

    National Aeronautics and Space Administration — This data product contains TOMS/EP UV Aerosol Index Daily and Monthly Zonal Means Version 8 data in ASCII format. (The shortname for this Level-3 Earth Probe TOMS...

  4. HIRDLS/Aura Level 3 Nitrogen Dioxide (NO2) Zonal Fourier Coefficients V007

    Data.gov (United States)

    National Aeronautics and Space Administration — The "HIRDLS/Aura Level 3 Nitrogen Dioxide (NO2) Zonal Fourier Coefficients" version 7 data product (H3ZFCNO2) contains the entire mission (~3 years) of HIRDLS data...

  5. Currents, HF Radio-derived, Bodega Bay, 25 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 25 hour running average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN...

  6. Currents, HF Radio-derived, Bodega Bay, 1 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 1 hour average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN EXPERIMENTAL...

  7. Currents, HF Radio-derived, Ano Nuevo, 1 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 1 hour average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN EXPERIMENTAL...

  8. Zonal jets in equilibrating baroclinic instability on the polar beta-plane: experiments with altimetry

    CERN Document Server

    Matulka, A M

    2015-01-01

    Results from the laboratory experiments on the evolution of baroclinically unstable flows generated in a rotating tank with topographic beta-effect are presented. We study zonal jets of alternating direction which occur in these flows. The primary system we model includes lighter fluid in the South and heavier fluid in the North with resulting slow meridional circulation and fast mean zonal motion. In a two-layer system the velocity shear between the layers results in baroclinic instability which equilibrates with time and, due to interaction with beta-effect generates zonal jets. This system is archetypal for various geophysical systems including the general circulation and jet streams in the Earths atmosphere, the Antarctic Circumpolar Current or the areas in the vicinity of western boundary currents where baroclinic instability and multiple zonal jets are observed. The gradient of the surface elevation and the thickness of the upper layer are measured in the experiments using the Altimetric Imaging Velocim...

  9. Currents, HF Radio-derived, Ano Nuevo, Normal Model, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements, with missing values filled in by a normal model....

  10. Currents, HF Radio-derived, Ano Nuevo, 25 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 25 hour running average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN...

  11. Wind Diffusivity Current, METOP ASCAT, 0.25 degrees, Global, Near Real Time, Zonal

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes near real time Ekman current (in zonal, meridional, and modulus sets) and Ekman upwelling data. This data begins with wind velocity...

  12. Currents, HF Radio-derived, SF Bay Outlet, Normal Model, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements, with missing values filled in by a normal model....

  13. Regulation of electron temperature gradient turbulence by zonal flows driven by trapped electron modes

    Energy Technology Data Exchange (ETDEWEB)

    Asahi, Y., E-mail: y.asahi@nr.titech.ac.jp; Tsutsui, H.; Tsuji-Iio, S. [Tokyo Institute of Technology, Tokyo 152-8550 (Japan); Ishizawa, A.; Watanabe, T.-H. [National Institute for Fusion Science, Gifu 509-5292 (Japan)

    2014-05-15

    Turbulent transport caused by electron temperature gradient (ETG) modes was investigated by means of gyrokinetic simulations. It was found that the ETG turbulence can be regulated by meso-scale zonal flows driven by trapped electron modes (TEMs), which are excited with much smaller growth rates than those of ETG modes. The zonal flows of which radial wavelengths are in between the ion and the electron banana widths are not shielded by trapped ions nor electrons, and hence they are effectively driven by the TEMs. It was also shown that an E × B shearing rate of the TEM-driven zonal flows is larger than or comparable to the growth rates of long-wavelength ETG modes and TEMs, which make a main contribution to the turbulent transport before excitation of the zonal flows.

  14. HIRDLS/Aura Level 3 Water Vapor (H2O) Zonal Fourier Coefficients V007

    Data.gov (United States)

    National Aeronautics and Space Administration — The "HIRDLS/Aura Level 3 Water Vapor (H2O) Zonal Fourier Coefficients" version 7 data product (H3ZFCH2O) contains the entire mission (~3 years) of HIRDLS data...

  15. HIRDLS/Aura Level 3 Geopotential Height Zonal Fourier Coefficients V007

    Data.gov (United States)

    National Aeronautics and Space Administration — The "HIRDLS/Aura Level 3 Geopotential Height Zonal Fourier Coefficients" version 7 data product (H3ZFCGPH) contains the entire mission (~3 years) of HIRDLS data...

  16. HIRDLS/Aura Level 3 Chlorofluorocarbon-12 (CFC-12) Zonal Fourier Coefficients V007

    Data.gov (United States)

    National Aeronautics and Space Administration — The "HIRDLS/Aura Level 3 Chlorofluorocarbon-12 (CFC-12) Zonal Fourier Coefficients" version 7 data product (H3ZFCCFC12) contains the entire mission (~3 years) of...

  17. HIRDLS/Aura Level 3 Dinitrogen Pentoxide (N2O5) Zonal Fourier Coefficients V007

    Data.gov (United States)

    National Aeronautics and Space Administration — The "HIRDLS/Aura Level 3 Dinitrogen Pentoxide (N2O5) Zonal Fourier Coefficients" version 7 data product (H3ZFCN2O) contains the entire mission (~3 years) of HIRDLS...

  18. HIRDLS/Aura Level 3 Extinction at 8.3 Microns Zonal Fourier Coefficients V007

    Data.gov (United States)

    National Aeronautics and Space Administration — The "HIRDLS/Aura Level 3 Extinction at 8.3 Microns Zonal Fourier Coefficients" version 7 data product (H3ZFC8MEXT) contains the entire mission (~3 years) of HIRDLS...

  19. HIRDLS/Aura Level 3 Nitric Acid (HNO3) Zonal Fourier Coefficients V007

    Data.gov (United States)

    National Aeronautics and Space Administration — The "HIRDLS/Aura Level 3 Nitric Acid (HNO3) Zonal Fourier Coefficients" version 7 data product (H3ZFCHNO3) contains the entire mission (~3 years) of HIRDLS data...

  20. Wind Stress, METOP ASCAT, 0.25 degrees, Global, Near Real Time, Zonal

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes near real time wind stress data in zonal, meridional, modulus, and wind stress curl sets. This data begins with wind velocity...

  1. Currents, HF Radio-derived, Monterey Bay, Normal Model, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements, with missing values filled in by a normal model....

  2. Currents, HF Radio-derived, Monterey Bay, 25 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 25 hour running average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN...

  3. Stellar Occultations from Airborne Platforms: 1988 to 2016

    Science.gov (United States)

    Bosh, Amanda S.; Dunham, Edward W.; Zuluaga, Carlos; Levine, Stephen; Person, Michael J.; Van Cleve, Jeffrey E.

    2016-10-01

    Observing a stellar occultation by a solar system body with an airborne telescope requires precise positioning of the observer within the shadow cast onto the Earth. For small bodies like Pluto and Kuiper Belt objects, smaller than the Earth, the challenge is particularly intense, with the accuracy of the astrometric and flight planning determining whether the observation succeeds or fails. From our first airborne occultation by Pluto in 1988 aboard the Kuiper Airborne Observatory (KAO), to our most recent event by Pluto in 2015 aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA), we have refined our astrometric and flight planning systems to the point where we can now place an airborne observer into the small central flash zone. We will discuss the history of airborne observation of occultations while detailing the improvements in the astrometric processes. Support for this work was provided by NASA SSO grant NNX15AJ82G to Lowell Observatory.

  4. Detection of occult metastasis in patients with breast cancer.

    Science.gov (United States)

    Hawes, D; Neville, A M; Cote, R J

    2001-06-01

    The most important factor affecting the outcome of patients with invasive cancer is whether the tumor has spread, either regionally (to regional lymph nodes) or systemically. However, a proportion of patients with no evidence of systemic dissemination will develop recurrent disease after primary "curative" therapy. Clearly, these patients had occult systemic spread of disease that was undetectable by routinely employed methods (careful pathological, clinical, biochemical, and radiological evaluation). In addition, the success of adjuvant therapy is assumed to stem from its ability to eradicate occult metastases before they become clinically evident. Therefore, methods for the detection of occult metastases in patients with the earliest stage of cancer, i.e., prior to detection of metastases by any other clinical or pathological analysis, have received a great deal of attention.

  5. Benefits and harms of detecting clinically occult breast cancer.

    Science.gov (United States)

    Amir, Eitan; Bedard, Philippe L; Ocaña, Alberto; Seruga, Bostjan

    2012-10-17

    Over the last few decades there has been an increase in the use of strategies to detect clinically occult breast cancer with the aim of achieving diagnosis at an earlier stage when prognosis may be improved. Such strategies include screening mammography in healthy women, diagnostic imaging and axillary staging in those diagnosed with breast cancer, and the use of follow-up imaging for the early detection of recurrent or metastatic disease. Some of these strategies are established, whereas for others there are inconsistent supportive data. Although the potential benefit of early detection of clinically occult breast cancer seems intuitive, use of such strategies can also be associated with harm. In this commentary, we provide an extended discussion on the potential benefits and harms of the routine and frequent use of screening interventions to detect clinically occult breast cancer and question whether we may be causing more harm than good.

  6. Categorizing the Occult: Vodun, Sorcery and Religious Beliefs In Benin

    DEFF Research Database (Denmark)

    Strandsbjerg, Camilla

    2011-01-01

    In everyday life in Benin as well as in academic research on the topic, the terms of vodun, witchcraft and the occult are often used in a non distinct way covering quite similar phenomena while at the same time referring to different kinds of beliefs and practices. The problem of understanding...... the magic, the mystical and the “occult” and particularly the difficulties of transmission in analytical terms of these phenomena have accompanied the production of anthropological knowledge since the early days of the discipline. However, in Benin, researchers in all domains of life are continuously...... characterized as witchcraft or occult. Reflecting upon earlier research and particularly on the choice of terminology of the occult in writing on religion and political change in Benin (PhD thesis 2008), this paper seeks to clarify some of the epistemological, academic and historical reasons that have formed...

  7. Occult sporadic insulinoma:Localization and surgical strategy

    Institute of Scientific and Technical Information of China (English)

    Bassam Abboud; Joe Boujaoude

    2008-01-01

    Insulinomas continue to pose a diagnostic challenge to physicians,surgeons and radiologists alike.Most are intrapancreatic,benign and solitary.Biochemical diagnosis is obtained and imaging techniques to localize lesions continue to evolve.Surgical resection is the treatment of choice.Despite all efforts,an occult insulinoma (occult insulinoma refers to a biochemically proven tumor with indeterminate anatomical site before operation) may still be encountered.New localization preoperative techniques decreases occult cases and the knowledge of the site of the mass before surgery allows to determine whether enucleation of the tumor or pancreatic resection is likely to be required and whether the tumor is amenable to removal via a laparoscopic approach.In absence of preoperative localization and intraoperative detection of an insulinoma,blind pancreatic resection is not recommended.

  8. Zonal Flow Patterns: How Toroidal Coupling Induces Phase Jumps and Shear Layers

    CERN Document Server

    Guo, Z B

    2016-01-01

    A new, frequency modulation mechanism for zonal flow pattern formation is presented. The model predicts the probability distribution function of the flow strength as well as the evolution of the characteristic spatial scale. Magnetic toroidicity-induced global phase dynamics is shown to determine the spatial structure of the flow. A key result is the observation that global phase patterning can lead to zonal flow formation in the absence of turbulence inhomogeneity.

  9. On the parameterization scheme of gravity wave drag effect on the mean zonal flow of mesosphere

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Based on McFarlane's parameterization scheme of gravity wave drag, a refined gravity-wave-drag scheme is presented. Both the drag effect of the momentum flux and the dissipation effect of gravity wave breaking on the mean zonal flow are included in the refined parameterization scheme. The dissipation effect can be formulated with the gravity wave numbers and the mean quantities. The refined parameterization scheme may represent a complete drag effect of stationary gravity wave breaking on the mean zonal flow.

  10. Assessment of NOAA NUCAPS upper air temperature profiles using COSMIC GPS radio occultation and ARM radiosondes

    Science.gov (United States)

    Feltz, M. L.; Borg, L.; Knuteson, R. O.; Tobin, D.; Revercomb, H.; Gambacorta, A.

    2017-09-01

    The U.S. National Oceanic and Atmospheric Administration (NOAA) recently began operational processing to derive vertical temperature profiles from two new sensors, Cross-Track Infrared Sounder and Advanced Technology Microwave Sounder, which were developed for the next generation of U.S. weather satellites. The NOAA-Unique Combined Atmospheric Processing System (NUCAPS) has been developed by NOAA to routinely process data from future Joint Polar Satellite System operational satellites and the preparatory Suomi-NPP satellite. This paper assesses the NUCAPS vertical temperature profile product from the upper troposphere into the middle stratosphere using radiosonde and GPS radio occultation (RO) data. Radiosonde data from the Department of Energy Atmospheric Radiation Measurement (ARM) program are=] compared to both the NUCAPS and GPS RO temperature products to evaluate bias and RMS errors. At all three fixed ARM sites for time periods investigated the NUCAPS temperature in the 100-40 hPa range is found to have an average bias to the radiosondes of less than 0.45 K and an RMS error of less than 1 K when temperature averaging kernels are applied. At a 95% confidence level, the radiosondes and RO were found to agree within 0.4 K at the North Slope of Alaska site and within 0.83 K at Southern Great Plains and Tropical Western Pacific. The GPS RO-derived dry temperatures, obtained from the University Corporation for Atmospheric Research Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) mission, are used as a common reference for the intercomparison of NUCAPS temperature products to similar products produced by NASA from Atmospheric Infrared Sounder (AIRS) and by European Organisation for the Exploitation of Meteorological Satellites from MetOp-B Infrared Atmospheric Sounding Interferometer (IASI). For seasonal and zonal scales, the NUCAPS agreement with AIRS and IASI is less than 0.5 K after application of averaging kernels.

  11. Quantification of structural uncertainty in climate data records from GPS radio occultation

    Directory of Open Access Journals (Sweden)

    A. K. Steiner

    2013-02-01

    Full Text Available Global Positioning System (GPS radio occultation (RO has provided continuous observations of the Earth's atmosphere since 2001 with global coverage, all-weather capability, and high accuracy and vertical resolution in the upper troposphere and lower stratosphere (UTLS. Precise time measurements enable long-term stability but careful processing is needed. Here we provide climate-oriented atmospheric scientists with multicenter-based results on the long-term stability of RO climatological fields for trend studies. We quantify the structural uncertainty of atmospheric trends estimated from the RO record, which arises from current processing schemes of six international RO processing centers, DMI Copenhagen, EUM Darmstadt, GFZ Potsdam, JPL Pasadena, UCAR Boulder, and WEGC Graz. Monthly-mean zonal-mean fields of bending angle, refractivity, dry pressure, dry geopotential height, and dry temperature from the CHAMP mission are compared for September 2001 to September 2008. We find that structural uncertainty is lowest in the tropics and mid-latitudes (50° S to 50° N from 8 km to 25 km for all inspected RO variables. In this region, the structural uncertainty in trends over 7 yr is <0.03% for bending angle, refractivity, and pressure, <3 m for geopotential height of pressure levels, and <0.06 K for temperature; low enough for detecting a climate change signal within about a decade. Larger structural uncertainty above about 25 km and at high latitudes is attributable to differences in the processing schemes, which undergo continuous improvements. Though current use of RO for reliable climate trend assessment is bound to 50° S to 50° N, our results show that quality, consistency, and reproducibility are favorable in the UTLS for the establishment of a climate benchmark record.

  12. Quantification of structural uncertainty in climate data records from GPS radio occultation

    Directory of Open Access Journals (Sweden)

    A. K. Steiner

    2012-10-01

    Full Text Available Global Positioning System (GPS radio occultation (RO provides continuous observations of the Earth's atmosphere since 2001 with global coverage, all-weather capability, and high accuracy and vertical resolution in the upper troposphere and lower stratosphere (UTLS. Precise time measurements enable long-term stability but careful processing is needed. Here we provide climate-oriented atmospheric scientists with multicenter-based results on the long-term stability of RO climatological fields for trend studies. We quantify the structural uncertainty of atmospheric trends estimated from the RO record, which arises from current processing schemes of six international RO processing centers, DMI Copenhagen, EUM Darmstadt, GFZ Potsdam, JPL Pasadena, UCAR Boulder, and WEGC Graz. Monthly-mean zonal-mean fields of bending angle, refractivity, dry pressure, dry geopotential height, and dry temperature from the CHAMP mission are compared for September 2001 to September 2008. We find that structural uncertainty is lowest in the tropics and mid-latitudes (50° S to 50° N from 8 km to 25 km for all inspected RO variables. In this region, the structural uncertainty in trends over 7 yr is <0.03% f or bending angle, refractivity, and pressure, <3 m for geopotential height of pressure levels, and <0.06 K for temperature; low enough for detecting a climate change signal within about a decade. Larger structural uncertainty above about 25 km and at high latitudes is attributable to differences in the processing schemes, which undergo continuous improvements. Though current use of RO for reliable climate trend assessment is bound to 50° S to 50° N, our results show that quality, consistency, and reproducibility are favorable in the UTLS for the establishment of a climate benchmark record.

  13. The occultation of Surrealism: a study of the relationship between Bretonian Surrealism and western esotericism

    NARCIS (Netherlands)

    Bauduin, T.M.

    2012-01-01

    It has been said that Surrealism was nothing if not deeply involved with occultism and Western esotericism. Others claim that there was no such involvement or even that Surrealism was directly opposed to the occult and esoteric. ‘The occultation of Surrealism’ offers a fresh view of this complex and

  14. The occultation of Surrealism: a study of the relationship between Bretonian Surrealism and western esotericism

    NARCIS (Netherlands)

    Bauduin, T.M.

    2012-01-01

    It has been said that Surrealism was nothing if not deeply involved with occultism and Western esotericism. Others claim that there was no such involvement or even that Surrealism was directly opposed to the occult and esoteric. ‘The occultation of Surrealism’ offers a fresh view of this complex and

  15. GRAS radio occultation on-board of Metop

    Science.gov (United States)

    von Engeln, A.; Andres, Y.; Marquardt, C.; Sancho, F.

    2011-01-01

    The GRAS radio occultation instrument is flying on Metop-A and belongs to the EPS (EUMETSAT Polar System). GRAS observes GPS satellites in occultation. Within this work, validation of GRAS closed-loop bending angle data against co-located ECMWF profiles extracted from model fields and occultations from the COSMIC constellation of radio occultation instruments is shown. Results confirm the high data quality and robustness, where GRAS shows lower bending angle noise against ECMWF than COSMIC and in terms of occultations per day, one GRAS ≈ two COSMIC satellites. This is partly due to the operational setup of EPS. For the investigation we focus on two observation periods where updates in the ECMWF (March 2009) and COSMIC processing (October 2009) have improved the statistics further. Bending angles biases agree to within 0.5% against ECMWF and to within 0.1% against COSMIC after the updates for altitudes between 8 and 40 km. In addition, we also analyze the impact of the Metop orbit processing on the derived GRAS bending angle data, where different GPS and Metop orbit solutions are analyzed. Results show that a batch based orbit processing would improve in particular the bending angle bias behavior at higher altitudes. Requirements for the operational processing of GRAS data are briefly outlined, options to ease the use of other positioning system satellites in the near future are discussed. A simplified analysis on the observation of several of these systems, e.g. GPS and Galileo, from one platform shows that about 16% of occultations are found within 300 km, ±3 h, thus providing similar information. A constellation of 2 GRAS like instruments would have only about 10% close-by.

  16. Constraints on Pluto's Hazes from 2-Color Occultation Lightcurves

    Science.gov (United States)

    Hartig, Kara; Barry, T.; Carriazo, C. Y.; Cole, A.; Gault, D.; Giles, B.; Giles, D.; Hill, K. M.; Howell, R. R.; Hudson, G.; Loader, B.; Mackie, J. A.; Olkin, C. B.; Rannou, P.; Regester, J.; Resnick, A.; Rodgers, T.; Sicardy, B.; Skrutskie, M. F.; Verbiscer, A. J.; Wasserman, L. H.; Watson, C. R.; Young, E. F.; Young, L. A.; Buie, M. W.; Nelson, M.

    2015-11-01

    The controversial question of aerosols in Pluto's atmosphere first arose in 1988, when features in a Pluto occultation lightcurve were alternately attributed to haze opacity (Elliot et al. 1989) or a thermal inversion (Eshleman 1989). A stellar occultation by Pluto in 2002 was observed from several telescopes on Mauna Kea in wavelengths ranging from R- to K-bands (Elliot et al. 2003). This event provided compelling evidence for haze on Pluto, since the mid-event baseline levels were systematically higher at longer wavelengths (as expected if there were an opacity source that scattered more effectively at shorter wavelengths). However, subsequent occultations in 2007 and 2011 showed no significant differences between visible and IR lightcurves (Young et al. 2011).The question of haze on Pluto was definitively answered by direct imaging of forward-scattering aerosols by the New Horizons spacecraft on 14-JUL-2015. We report on results of a bright stellar occultation which we observed on 29-JUN-2015 in B- and H-bands from both grazing and central sites. As in 2007 and 2011, we see no evidence for wavelength-dependent extinction. We will present an analysis of haze parameters (particle sizes, number density profiles, and fractal aggregations), constraining models of haze distribution to those consistent with and to those ruled out by the occultation lightcurves and the New Horizons imaging.References:Elliot, J.L., et al., "Pluto's Atmosphere." Icarus 77, 148-170 (1989)Eshleman, V.R., "Pluto's Atmosphere: Models based on refraction, inversion, and vapor pressure equilibrium." Icarus 80 439-443 (1989)Elliot, J.L., et al., "The recent expansion of Pluto's atmosphere." Nature 424 165-168 (2003)Young, E.F., et al., "Search for Pluto's aerosols: simultaneous IR and visible stellar occultation observations." EPSC-DPS Joint Meeting 2011, held 2-7 October 2011 in Nantes, France (2011)

  17. Advanced Electrocardiography Can Identify Occult Cardiomyopathy in Doberman Pinschers

    Science.gov (United States)

    Spiljak, M.; Petric, A. Domanjko; Wilberg, M.; Olsen, L. H.; Stepancic, A.; Schlegel, T. T.; Starc, V.

    2011-01-01

    Recently, multiple advanced resting electrocardiographic (A-ECG) techniques have improved the diagnostic value of short-duration ECG in detection of dilated cardiomyopathy (DCM) in humans. This study investigated whether 12-lead A-ECG recordings could accurately identify the occult phase of DCM in dogs. Short-duration (3-5 min) high-fidelity 12-lead ECG recordings were obtained from 31 privately-owned, clinically healthy Doberman Pinschers (5.4 +/- 1.7 years, 11/20 males/females). Dogs were divided into 2 groups: 1) 19 healthy dogs with normal echocardiographic M-mode measurements: left ventricular internal diameter in diastole (LVIDd . 47mm) and in systole (LVIDs . 38mm) and normal 24-hour ECG recordings (occult DCM: 11/12 dogs had increased M-mode measurements (LVIDd . 49mm and/or LVIDs . 40mm) and 5/11 dogs had also >100 VPCs/24h; 1/12 dogs had only abnormal 24-hour ECG recordings (>100 VPCs/24h). ECG recordings were evaluated via custom software programs to calculate multiple parameters of high-frequency (HF) QRS ECG, heart rate variability, QT variability, waveform complexity and 3-D ECG. Student's t-tests determined 19 ECG parameters that were significantly different (P occult DCM. For the 5 selected parameters the prediction of occult DCM was performed using a binary logistic regression model with Chi-square tested significance (P occult ECG with sensitivity 89% and specificity 83%. Results suggest that 12-lead A-ECG might improve diagnostic value of short-duration ECG in earlier detection of canine DCM as five selected ECG parameters can with reasonable accuracy identify occult DCM in Doberman Pinschers. Future extensive clinical studies need to clarify if 12-lead A-ECG could be useful as an additional screening test for canine DCM.

  18. Dynamics of Zonal FLow Instability and Saturation in Drift Wave Turbulence

    Science.gov (United States)

    Katt, S. T.; Kim, E.; Diamond, P. H.

    2001-10-01

    We study generalized Kelvin-Helmholtz (GKH) instability as a saturation mechanism for a collisionless zonal flow in the background of drift waves. By treating drift waves as adiabatically modified by GKH, we investigate the modulation instability of drift waves due to GKH modes as well as the linear inflection-type instability of zonal flow. In the case where zonal flows evolve on the time scale much larger than GKH mode, GKH mode is shown to become destabilized not only by the linear instability of zonal flow but also by coupling to drift waves, with a growth rate which is enhanced over the linear value. Furthermore, the nonlinear (modulational) generation of a zonal flow is estimated to dominate over that of GKH. Our results indicate that GKH may not play an important role in a collisionless saturation of zonal flow, in contrast to [1] and [2]. The effect of temperature fluctuation will be discussed. [1] B.N. Rogers, W. Dorland, and M. Kotschenreuther, PRL, 85, 5336, (2000). [2] Y. Idomura, M. Wakatani, and S. Tokuda, PoP, 7, 3551, (2000).

  19. Model test of anchoring effect on zonal disintegration in deep surrounding rock masses.

    Science.gov (United States)

    Chen, Xu-Guang; Zhang, Qiang-Yong; Wang, Yuan; Liu, De-Jun; Zhang, Ning

    2013-01-01

    The deep rock masses show a different mechanical behavior compared with the shallow rock masses. They are classified into alternating fractured and intact zones during the excavation, which is known as zonal disintegration. Such phenomenon is a great disaster and will induce the different excavation and anchoring methodology. In this study, a 3D geomechanics model test was conducted to research the anchoring effect of zonal disintegration. The model was constructed with anchoring in a half and nonanchoring in the other half, to compare with each other. The optical extensometer and optical sensor were adopted to measure the displacement and strain changing law in the model test. The displacement laws of the deep surrounding rocks were obtained and found to be nonmonotonic versus the distance to the periphery. Zonal disintegration occurs in the area without anchoring and did not occur in the model under anchoring condition. By contrasting the phenomenon, the anchor effect of restraining zonal disintegration was revealed. And the formation condition of zonal disintegration was decided. In the procedure of tunnel excavation, the anchor strain was found to be alternation in tension and compression. It indicates that anchor will show the nonmonotonic law during suppressing the zonal disintegration.

  20. Model Test of Anchoring Effect on Zonal Disintegration in Deep Surrounding Rock Masses

    Directory of Open Access Journals (Sweden)

    Xu-Guang Chen

    2013-01-01

    Full Text Available The deep rock masses show a different mechanical behavior compared with the shallow rock masses. They are classified into alternating fractured and intact zones during the excavation, which is known as zonal disintegration. Such phenomenon is a great disaster and will induce the different excavation and anchoring methodology. In this study, a 3D geomechanics model test was conducted to research the anchoring effect of zonal disintegration. The model was constructed with anchoring in a half and nonanchoring in the other half, to compare with each other. The optical extensometer and optical sensor were adopted to measure the displacement and strain changing law in the model test. The displacement laws of the deep surrounding rocks were obtained and found to be nonmonotonic versus the distance to the periphery. Zonal disintegration occurs in the area without anchoring and did not occur in the model under anchoring condition. By contrasting the phenomenon, the anchor effect of restraining zonal disintegration was revealed. And the formation condition of zonal disintegration was decided. In the procedure of tunnel excavation, the anchor strain was found to be alternation in tension and compression. It indicates that anchor will show the nonmonotonic law during suppressing the zonal disintegration.

  1. Atmospheric Response to Zonal Variations in Midlatitude SST: Transient and Stationary Eddies and Their Feedback(.

    Science.gov (United States)

    Inatsu, Masaru; Mukougawa, Hitoshi; Xie, Shang-Ping

    2003-10-01

    Midwinter storm track response to zonal variations in midlatitude sea surface temperatures (SSTs) has been investigated using an atmospheric general circulation model under aquaplanet and perpetual-January conditions. Zonal wavenumber-1 SST variations with a meridionally confined structure are placed at various latitudes. Having these SST variations centered at 30°N leads to a zonally localized storm track, while the storm track becomes nearly zonally uniform when the same SST forcing is moved farther north at 40° and 50°N. Large (small) baroclinic energy conversion north of the warm (cold) SST anomaly near the axis of the storm track (near 40°N) is responsible for the large (small) storm growth. The equatorward transfer of eddy kinetic energy by the ageostrophic motion and the mechanical damping are important to diminish the storm track activity in the zonal direction.Significant stationary eddies form in the upper troposphere, with a ridge (trough) northeast of the warm (cold) SST anomaly at 30°N. Heat and vorticity budget analyses indicate that zonally localized condensational heating in the storm track is the major cause for these stationary eddies, which in turn exert a positive feedback to maintain the localized storm track by strengthening the vertical shear near the surface. These results indicate an active role of synoptic eddies in inducing deep, tropospheric-scale response to midlatitude SST variations. Finally, the application of the model results to the real atmosphere is discussed.

  2. THE IMPROVEMENT OF THE COMPUTATIONAL PERFORMANCE OF THE ZONAL MODEL POMA USING PARALLEL TECHNIQUES

    Directory of Open Access Journals (Sweden)

    Yao Yu

    2014-01-01

    Full Text Available The zonal modeling approach is a new simplified computational method used to predict temperature distribution, energy in multi-zone building and indoor airflow thermal behaviors of building. Although this approach is known to use less computer resource than CFD models, the computational time is still an issue especially when buildings are characterized by complicated geometry and indoor layout of furnishings. Therefore, using a new computing technique to the current zonal models in order to reduce the computational time is a promising way to further improve the model performance and promote the wide application of zonal models. Parallel computing techniques provide a way to accomplish these purposes. Unlike the serial computations that are commonly used in the current zonal models, these parallel techniques decompose the serial program into several discrete instructions which can be executed simultaneously on different processors/threads. As a result, the computational time of the parallelized program can be significantly reduced, compared to that of the traditional serial program. In this article, a parallel computing technique, Open Multi-Processing (OpenMP, is used into the zonal model, Pressurized zOnal Model with the Air diffuser (POMA, in order to improve the model computational performance, including the reduction of computational time and the investigation of the model scalability.

  3. Occult hepatitis C virus infection in Iranian hemodialysis patients

    OpenAIRE

    Eslamifar, Ali; Ramezani, Amitis; Ehteram, Hassan; Razeghi, Effat; Ahmadi, Farrokhlagha; Amini, Manouchehr; Banifazl, Mohammad; Etemadi, Gelavizh; Keyvani, Hossein; Bavand, Anahita; Aghakhani, Arezoo

    2015-01-01

    Background: Occult hepatitis C virus (HCV) infection is defined as the presence of HCV-RNA in liver or peripheral blood mononuclear cells (PBMCs) in the absence of detectable hepatitis C antibody (anti-HCV) or HCV-RNA in the serum. Low concentrations of HCV-RNA may be detected in PBMCs of hemodialysis (HD) patients and this could have a great impact on the management of HD patients. Objectives: The aim of this study was to detect the occult HCV infection in Iranian HD patients. Patients and M...

  4. Radio occultation bending angle anomalies during tropical cyclones

    DEFF Research Database (Denmark)

    Biondi, Riccardo; Neubert, Torsten; Syndergaard, S.

    2011-01-01

    The tropical deep convection affects the radiation balance of the atmosphere changing the water vapor mixing ratio and the temperature of the upper troposphere lower stratosphere. The aim of this work is to better understand these processes and to investigate if severe storms leave a significant ...... Ensemble in Space (ACES) payload on the International Space Station....... signature in radio occultation profiles in the tropical tropopause layer. Using tropical cyclone best track database and data from different GPS radio occultation missions (COSMIC, GRACE, CHAMP, SACC and GPSMET), we selected 1194 profiles in a time window of 3 h and a space window of 300 km from the eye...

  5. Presentation of Axillary Metastases from Occult Breast Carcinoma

    Institute of Scientific and Technical Information of China (English)

    Xin Wang

    2007-01-01

    Axillary presentation from occult breast cancer is uncommon and continues to be a diagnostic and therapeutic challenge to physicians.Once the diagnosis of adenocarcinoma metastatic to an axillary lymph node has been confirmed,a preoperative workup should be done.The current experience is based on several relatively small retrospective reviews and case reports.It is difficult to determine the best management of occult breast cancer.However,treatmenl of axillary Iymph node dissection is recommended for local control and complete staging information.Treatment of breast should be a choice between breast conservation with whole-breast radiotherapy and mastectomy.Adjuvant systemic treatment should be offered.

  6. Forthcoming Occultations of Astrometric Radio Sources by Planets

    Science.gov (United States)

    L'vov, Victor; Malkin, Zinovy; Tsekmeister, Svetlana

    2010-01-01

    Astrometric observations of radio source occultations by solar system bodies may be of large interest for testing gravity theories, dynamical astronomy, and planetary physics. In this paper, we present an updated list of the occultations of astrometric radio sources by planets expected in the coming years. Such events, like solar eclipses, generally speaking can only be observed in a limited region. A map of the shadow path is provided for the events that will occurr in regions with several VLBI stations and hence will be the most interesting for radio astronomy experiments.

  7. Generation of a Bending Angle Radio Occultation Climatology (BAROCLIM and its use in radio occultation retrievals

    Directory of Open Access Journals (Sweden)

    B. Scherllin-Pirscher

    2014-08-01

    Full Text Available In this paper, we introduce a bending angle radio occultation climatology (BAROCLIM based on Formosat-3/COSMIC (F3C data. This climatology represents the monthly-mean atmospheric state from 2006 to 2012. Bending angles from radio occultation (RO measurements are obtained from the accumulation of the change in the raypath direction of Global Positioning System (GPS signals. Best quality of these near-vertical profiles is found from the middle troposphere up to the mesosphere. Beside RO bending angles we also use data from the Mass Spectrometer and Incoherent Scatter Radar (MSIS model to expand BAROCLIM in a spectral model, which (theoretically reaches from the surface up to infinity. Due to the very high quality of BAROCLIM up to the mesosphere, it can be used to detect deficiencies in current state-of-the-art analysis and reanalysis products from numerical weather prediction (NWP centers. For bending angles derived from European Centre for Medium-Range Weather Forecasts (ECMWF analysis fields from 2006 to 2012, e.g., we find a positive bias of 0.5% to % at 40 km, which increases to more than 2% at 50 km. BAROCLIM can also be used as a priori information in RO profile retrievals. In contrast to other a priori information (i.e., MSIS we find that the use of BAROCLIM better preserves the mean of raw RO measurements. Global statistics of statistically optimized bending angle and refractivity profiles also confirm that BAROCLIM outperforms MSIS. These results clearly demonstrate the utility of BAROCLIM.

  8. Occult intraspinal abnormalities and congenital scoliosis

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Erfani

    2007-06-01

    Full Text Available

    BACKGROUND: Congenital scoliosis occurs because of either the failure of formation or the failure of segmentation or both. Evaluation of the incidence and the types of occult intraspinal abnormalities in congenital scoliosis is the subject of this study.

    METHODS: During a period of 29 years, 103 patients with congenital scoliosis were studied. MRI was used in 46 patients, myelography or CT myelography was used in 64 patients and both MRI and myelography or CT myelography were used in 7 patients for intraspinal abnormalities.

    RESULTS: In the MRI group, among the 46 patients, 19 patients (41.3% had intraspinal abnormalities consisting syringomyelia in 9 (19.5% diastematomyelia in 8 (17.4%, tethered cord syndrome in 6 (13%, low conus in 5 (10.8% and diplomyelia in 3 (6.5% of the patients. In the myelography group, among the 64 patients, 17 (26.5% had intraspinal abnormalities and diastematomyelia was the most common one found in 14 (21.8% patients.

    CONCLUSIONS: Intraspinal abnormalities are frequent in congenital scoliosis. Syringomyelia may be associated with congenital scoliosis. In congenital scoliosis, rib fusion may be an indicator of intraspinal abnormalities in MRI. A significant difference between clinical findings and intraspinal anomalies (P<0.05 was noted. Moreover, we believe that total spinal MRI with coronal, sagittal and axial views is a valuable tool in determining the intraspinal abnormalities in congenital scoliosis. This method is highly

  9. Oh Glorious Geometry: Eclipses, Transits, and Occultations

    Science.gov (United States)

    Sinclair, R. M.

    2016-01-01

    Astronomical objects are like a grand clockwork in the sky; they follow steady patterns in time. However, these bright objects we see are not just points of light but have finite dimensions and thus can get in each other's way. As a result, some stars puzzle us by brightening or dimming, or the Sun can frighten us by going out unexpectedly when something else blocks its light. There is nothing unusual about these eclipses, occultations, or transits—they are demonstrations of simple physics—and we take some for granted, like the rotation of Earth moving us into darkness each night. The periodic dimming of a bright star worried mankind for millennia and helped give astronomy a shove. And unexpected events, like a solar or lunar eclipse, can inspire awe and change the course of history. Now that we can observe through telescopes and travel by proxy throughout the solar system, we find the universe is rife with shadow and light shows. Those taking place within our solar system have been useful to astronomy (like the recent transits of Venus or the ever-present eclipses of the Jovian satellites), and were of considerable popular interest, allowing us to think beyond the confines of Earth. Now we detect distant exoplanets transiting their parent stars, announcing the presence of other solar systems in our corner of the Galaxy and changing the discussion about life elsewhere in the universe from mere speculation to plausible possibility. Distant galaxies can make visible ever-further galaxies by forming Einstein rings, allowing us to see behind them and make the structure of the universe more evident. This paper will discuss these phenomena, from those visible easily on Earth to those that can now be seen for the first time from probes in space. We will also discuss how this has expanded popular knowledge of the universe we live in. This paper is illustrated by a number of examples ranging from eclipses and transits throughout the solar system and the nearby stars to

  10. Effects of plasma elongation on drift wave-zonal flow turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Angelino, P.; Garbet, X.; Grandgirard, V.; Sarazin, Y.; Ghendrih, P.; Dif-Pradalier, G.; Jolliet, S.; Bottino, A.; McMillan, B. F.; Tran, T. M.; Villard, L.

    2007-07-01

    The theoretical study of plasma turbulent transport is of central importance to fusion research. Experimental evidence indicates that the confinement time is in fact a consequence of the turbulent transport of energy. The magnitude of turbulent transport depends on the turbulent state resulting from nonlinear saturation mechanisms. The ion heat anomalous transport in the plasma core fusion devices seems to be dominated by a class of microinstabilities, the toroidal ion temperature gradient driven modes (ITGs). ITG turbulence is known to self organize to form coherent macroscopic structures extended in the direction perpendicular to the gradient. These structures are essentially axisymmetric flows denominated zonal flows. The amplitude of zonal flows can oscillate: these perturbations are known as Geodesic Acoustic Modes (GAMs). Zonal flows act as a regulating mechanism on plasma microturbulence, the saturated turbulent state being determined by the nonlinear interactions between ITGs, zonal flows and GAMs. We present an analytical study showing the strong impact that plasma geometry has on zonal flow collisionless linear damping. The GAM frequency is shown to scale inversely with the elongation and the aspect ratio. These results are supported by numerical linear analysis, which in addition shows that the GAM damping rate and the undamped zonal flow component are enhanced by elongation and smaller aspect ratio. The same parameters also modify the ITG linear growth rates. Therefore linear analysis suggests that geometry can play a role in the determination of the turbulent transport level. On the other hand, the extent of this action can be quantified only by means of full nonlinear calculations. We present the results of nonlinear gyrokinetic simulations in realistic tokamak magnetohydrodynamic equilibria, focusing on the role of plasma elongation. The effect of the variation of this parameter on the ion heat transport and zonal flow-GAM interactions is

  11. Advances in Fecal Occult Blood Tests: The FIT Revolution

    NARCIS (Netherlands)

    G.P. Young; E.L. Symonds (Erin L.); J.E. Allison (James E.); S.R. Cole (Stephen R.); C.G. Fraser (Callum G.); S. Halloran (S.); E.J. Kuipers (Ernst); H.E. Seaman (Helen E.)

    2015-01-01

    textabstractThere is a wide choice of fecal occult blood tests (FOBTs) for colorectal cancer screening. Goal: To highlight the issues applicable when choosing a FOBT, in particular which FOBT is best suited to the range of screening scenarios. Four scenarios characterize the constraints and expectat

  12. Occult Dirofilariosis in Dogs of North Eastern Region in India

    Directory of Open Access Journals (Sweden)

    Sonjoy Kumar-Borthakur

    2015-10-01

    Full Text Available Background: The North Eastern Region in India is endemic for canine heartworm disease but in clinics accurate diagnosis is some times difficult. The aim of the present study was to determine the prevalence of occult infections for heartworm disease in canine in two geographical regions of North Eastern India.Methods: A total of 782 numbers of three categories of dogs namely, working dogs of military and paramilitary forces, pet dogs and stray dogs were screened for the presence of heartworm infection from August 2011 to July, 2012 in Guwahati (Assam and Aizawl (Mizoram. Conventional, immunological and molecular techniques were followed for this epidemiological study. The criteria to determine the occult heartworm cases were based on the dif­ferences between heartworm positive cases in PCR test and antigen ELISA test.Results: The findings revealed an overall 22.69 percent occult case. The working dogs had highest prevalence (60% followed by pet (29.16% and stray dogs (17.75%.Conclusion: The highest percentage of occult heartworm infection was present in working dogs maintained under military or paramilitary forces. 

  13. Solar occultation with SCIAMACHY: algorithm description and first validation

    Directory of Open Access Journals (Sweden)

    J. Meyer

    2005-01-01

    Full Text Available This presentation concentrates on solar occultation measurements with the spaceborne spectrometer SCIAMACHY in the UV-Vis wavelength range. Solar occultation measurements provide unique information about the vertical distribution of atmospheric constituents. For retrieval of vertical trace gas concentration profiles, an algorithm has been developed based on the optimal estimation method. The forward model is capable to simulate the extinction signals of different species as they occur in atmospheric transmission spectra obtained from occultation measurements. Furthermore, correction algorithms have been implemented to address shortcomings of the tangent height pre-processing and inhomogeneities of measured solar spectra. First results of O3 and NO2 vertical profile retrievals have been validated with data from ozone sondes and satellite based occultation instruments. The validation shows very promising results for SCIAMACHY O3 and NO2 values between 15 to 35 km with errors in the order of 10% and 15%, respectively.

  14. Radio occultation bending angle anomalies during tropical cyclones

    Directory of Open Access Journals (Sweden)

    R. Biondi

    2011-02-01

    Full Text Available The tropical deep convection affects the radiation balance of the atmosphere changing the water vapor mixing ratio and the temperature of the upper troposphere lower stratosphere. The aim of this work is to better understand these processes and to investigate if severe storms leave a significant signature in radio occultation profiles in the tropical tropopause layer. Using tropical cyclone best track database and data from different GPS radio occultation missions (COSMIC, GRACE, CHAMP, SACC and GPSMET, we selected 1194 profiles in a time window of 3 h and a space window of 300 km from the eye of the cyclone. We show that the bending angle anomaly of a GPS radio occultation signal is typically larger than the climatology in the upper troposphere and lower stratosphere and that a double tropopause during deep convection can easily be detected using this technique. Comparisons with co-located radiosondes, climatology of tropopause altitudes and GOES analyses are also shown to support the hypothesis that the bending angle anomaly can be used as an indicator of convective towers. The results are discussed in connection to the GPS radio occultation receiver which will be part of the Atomic Clock Ensemble in Space (ACES payload on the International Space Station.

  15. Occult hepatitis B among Iranian hepatitis C patients

    Directory of Open Access Journals (Sweden)

    Ahmad shavakhi

    2009-02-01

    Full Text Available

    • BACKGROUND: Occult hepatitis B is defined as presence of HBV DNA in tissue or serum without hepatitis B surface antigen. The aim of this study is to determine frequency of occult hepatitis B among hepatitis C patients in Tehran and compare the route of transmission and liver enzymes between positive and negative HBV DNA patients.
    • METHODS: In a cross sectional study, serum of 103 hepatitis C cases (79.6% men and 20.4% women were analyzed for s, x and core genes via a nested polymerase chain reaction technique.
    • RESULTS: HBV DNA was detectable in serum of 20 patients (19.4%. No significant difference in age, sex and route of transmission were seen in HBV DNA positive and negative patients. In HBV DNA positive and negative groups, mean of AST was 73, 47 (p < 0.05 and mean of ALT was 76 and 36 respectively (p < 0.05.
    • CONCLUSION: Occult hepatitis B was observed in a considerable number of hepatitis C patients in Tehran. It was associated with elevation in liver enzyme but was not related to route of transmission.
    • KEY WORD: Occult hepatitis B, hepatitis C, cirrhosis.

  16. Counseling the Occult-Involved Student: Guidelines and Suggestions.

    Science.gov (United States)

    Carmichael, Karla D.

    1993-01-01

    Contends that counselors working with public school students needs to be aware of the four main levels of involvement in the occult (fun-and-games, dabblers, serious involvement, and criminal involvement). Each of the four levels is described, warning signs are identified, and the counselor's role is explained as one of support and prevention. (NB)

  17. The Effect of Diurnal Variations on Ionospheric Radio Occultations

    Science.gov (United States)

    Yelle, Roger V.; Koskinen, Tommi; Withers, Paul; Schinder, Paul J.; Moses, Julianne I.; Mueller-Wodarg, Ingo

    2016-10-01

    Radio occultations are a powerful technique for the study of atmospheres and ionospheres by planetary spacecraft. For missions to the outer solar system, the occultations always probe the terminator region of the planet. The analysis of radio occultations typically assumes symmetry along the ray path in the horizontal direction about the tangent point. While this is an excellent assumption for the neutral atmosphere where the scale length of horizontal gradients is large, it is suspect for the ionosphere where electron densities decrease rapidly from day to night. Diurnal variations in peak electron density are often several orders of magnitude and may occur over a region of a few degrees. We investigate the consequences of diurnal variations on ionospheric occultations with a ray tracing calculation for the angular deflection and frequency residual of the radio wave. The calculations are based on photochemical/diffusion models for the ionospheres of Saturn and Titan. Differences from analysis based on the assumption of horizontal symmetry are most pronounced in the bottom side ionosphere where chemical time constants are short.

  18. The Structure of Enceladus' Plume from Cassini Occultation Observations

    Science.gov (United States)

    Hansen, C. J.; Esposito, L. W.; Buffington, B. B.; Colwell, J.; Hendrix, A. R.; Meinke, B. K.; Shemansky, D. E.; Stewart, I.; West, R. A.

    2011-12-01

    Cassini's Ultraviolet Imaging Spectrograph (UVIS) has observed 2 stellar and one solar occultation by Enceladus' water vapor plume. These observations have established that water is the primary constituent of the plume, allowed us to calculate the flux of water coming from the plume, and detected super-sonic jets of gas imbedded within the plume [1]. On 19 October 2011 two stars (epsilon and zeta Orionis) will simultaneously be occulted by the plume, and the signal of the two will be in separate pixels on the detector. This is a tangential occultation that will provide a horizontal cut through the plume at two altitudes. The two stars are separated by 24 mrad, or ~20 km, with the lower altitude star 18 km above the limb at its closest point. The groundtrack is similar to the 2010 solar occultation, but viewed from the other side of the plume. Results from this new data set with implications for the vertical structure of the plume and jets will be presented.

  19. Lichen scrofulosorum: An important marker of occult tuberculosis

    Directory of Open Access Journals (Sweden)

    Dogra Naina

    2008-01-01

    Full Text Available Lichen scrofulosorum is a tuberculid that is usually seen in children or young adults. Although a rare occurrence, this tuberculid is an important marker of occult tuberculosis, which may not be detected otherwise. We report here a case of lichen scrofulosorum in a ten year-old boy with typical grouped lichenoid papules on the trunk associated with axillary tuberculous lymphadenitis.

  20. Effects of menopausal hormonal therapy on occult breast tumors.

    Science.gov (United States)

    Santen, Richard J; Song, Yan; Yue, Wei; Wang, Ji-Ping; Heitjan, Daniel F

    2013-09-01

    An estimated 7% of 40-80 year old women dying of unrelated causes harbor occult breast tumors at autopsy. These lesions are too small to be detected by mammography, a method which requires tumors to be approximately 1cm in diameter to be diagnosed. Tumor growth rates, as assessed by "effective doubling times" on serial mammography range from 10 to >700 days with a median of approximately 200 days. We previously reported two models, based on iterative analysis of these parameters, to describe the biologic behavior of undiagnosed, occult breast tumors. One of our models is biologically based and includes parameters of a 200 day effective doubling time, 7% prevalence of occult tumors in the 40-80 aged female population and a detection threshold of 1.16 cm and the other involves computer based projections based on age related breast cancer incidence. Our models facilitate interpretation of the Women's Health Initiative (WHI) and anti-estrogen prevention studies. The biologically based model suggests that menopausal hormone therapy with conjugated equine estrogens plus medroxyprogesterone acetate (MPA) in the WHI trial primarily promoted the growth of pre-existing, occult lesions and minimally initiated de novo tumors. The paradoxical reduction of breast cancer incidence in women receiving estrogen alone is consistent with a model that this hormone causes apoptosis in women deprived of estrogen long term as a result of the cessation of estrogen production after the menopause. Understanding of the kinetics of occult tumors suggests that breast cancer "prevention" with anti-estrogens or aromatase inhibitors represents early treatment rather than a reduction in de novo tumor formation. Our in vivo data suggest that the combination of a SERM, bazedoxifene (BZA), with conjugated equine estrogen (CEE) acts to block maturation of the mammary gland in oophorectomized, immature mice. This hormonal combination is defined by the generic term, tissue selective estrogen complex or

  1. The 2010, February 19 stellar occultation by Varuna

    Science.gov (United States)

    Sicardy, Bruno; Colas, F.; Maquet, L.; Vachier, F.; Doressoundiram, A.; Roques, F.; Widemann, T.; Ortiz, J.; Assafin, M.; Braga-Ribas, F.; Camargo, J. I. B.; Vieira-Martins, R.; Andrei, A.; da Silva Neto, D.; Behrend, R.; Hund, F.; Hauser, M.; Wagner, S.; Slotegraaf, A.; Willasch, D.; Costa, M. de Jesus; Melo Sousa, P.; Faustino, E.; Prazeres, A.; Machado, S.; Dias do Nascimento, J.; Souza Barreto, E.; Amorim, A.; da Rocha Poppe, P.; Pereira, M. Geraldete; Jacques, C.; Loureiro Giacchini, B.; Collucci, A.; Ferreira da Costa, W.; Martins de Morais, V.

    2010-10-01

    On 2010, February 19, Varuna occulted UCAC2 star 41014042, as seen from regions in southern Africa and north-eastern Brazil. No occultation was observed neither from the station deployed in South Africa, nor from three other stations in Namibia. Out of twelve stations deployed in Brazil, seven had clouds or instrument malfunctions. Three were negative, one possibly positive (visual) is still being analyzed, and one is definitely positive from Sao Luis (CCD). This makes Varuna the most remote solar system object observed to date through a stellar occultation, with a geocentric distance of 6.4 billions km. The Sao Luis occultation has a duration of 52.5 +/- 0.5 sec, corresponding to a chord length of 1003 +/- 9 km projected in the plane of the sky. No atmospheric signature is apparent in the light curve. Since the closest observation to Sao Luis is negative at a transversal distance of 225 km (Quixada, CCD), a significantly elongated shape is required for Varuna. We will discuss our results in view of current independent estimations of Varuna's diameter combining IR thermal and visible data, with a typical value of 1050 km +/- 200 km (Lellouch et al. 2002, Stansberry et al., 2008). We will also discuss the fact that the occultation occurred near Varuna's maximum brightness along its 6.4 hr rotational (0.4-mag amplitude) light curve. Thus Varuna was observed at maximum apparent surface area, which also corresponds to maximum apparent oblateness for an ellipsoidal shape. Lellouch et al, Astron. Astrophys. 391, 1133-1139 (2002). Stansberry et al., in The Solar System beyond Neptune (eds Barucci, M. A.,Boehnhardt, H., Cruikshank, D. P. & Morbidelli, A.) 161-179 (Univ. Arizona Press, 2008). This work is partially supported by french ANR 08-BLAN-0177 "Beyond Neptune".

  2. Treatment outcomes of occult breast carcinoma and prognostic analyses

    Institute of Scientific and Technical Information of China (English)

    WANG Jing; ZHANG Ye-fan; WANG Xin; WANG Jian; YANG Xue; GAO Yin-qi; FANG Yi

    2013-01-01

    Background The surgical management of occult breast cancer is controversial.We compared the outcomes of different treatments of occult breast cancer and evaluated the potential prognostic factors for overall survival and recurrence.Methods We retrospectively reviewed 77 patients who presented to our hospital from 1968 to 2011 with a diagnosis of occult breast cancer.Patients were divided into three groups:42 patients (63%) were treated with modified radical mastectomy+axillary lymph node dissection (ALND),16 patients (24%) were treated with ALND+postoperative radiotherapy,and 9 patients (13%) with only ALND.Survival analyses were undertaken to compare the efficacy of these three treatments.Results Of the 77 patients with occult breast cancer,2 patients were lost to follow-up and 8 patients refused surgical treatment:67 patients (90.4%) were included in this analysis.The median follow-up was 62.2 (0.6-328.0)months.Kaplan-Meier analyses showed no significant difference in overall survival and recurrence-free survival between the three groups (P=0.494 and 0.397,respectively).The prevalence of local recurrence was 11.9% for the mastectomy+ALND,18.8% for ALND+radiotherapy,and 11.1% for ALND-only groups,and those for distant recurrence were 2.4%,12.5%,and 11.1%,respectively.Compared with progesterone receptor-negative subjects,progesterone receptor-positive patients had better overall survival and lower recurrence rates (P=0.057 and 0.062,respectively).Conclusions There was no significant difference in outcomes between mastectomy and breast-preserving surgery.Expression of the progesterone receptor should be taken into account when evaluating the prognosis of occult breast cancer.

  3. Indian Ocean zonal mode activity in 20th century observations and simulations

    Science.gov (United States)

    Sendelbeck, Anja; Mölg, Thomas

    2016-04-01

    The Indian Ocean zonal mode (IOZM) is a coupled ocean-atmosphere system with anomalous cooling in the east, warming in the west and easterly wind anomalies, resulting in a complete reversal of the climatological zonal sea surface temperature (SST) gradient. The IOZM has a strong influence on East African climate by causing anomalously strong October - December (OND) precipitation. Using observational data and historical CMIP5 (Coupled Model Intercomparison Project phase 5) model output, the September - November (SON) dipole mode index (DMI), OND East African precipitation and SON zonal wind index (ZWI) are calculated. We pay particular attention to detrending SSTs for calculating the DMI, which seems to have been neglected in some published research. The ZWI is defined as the area-averaged zonal wind component at 850 hPa over the central Indian Ocean. Regression analysis is used to evaluate the models' capability to represent the IOZM and its impact on east African climate between 1948 and 2005. Simple correlations are calculated between SST, zonal wind and precipitation to show their interdependence. High correlation in models implies a good representation of the influence of IOZM on East African climate variability and our goal is to detect the models with the highest correlation coefficients. In future research, these model data might be used to investigate the impact of IOZM on the East African climate variability in the late 20's century with regard to anthropogenic causes and internal variability.

  4. Mechanism of zonal disintegration in surrounding rock mass around deep rock engineering and its application

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The mechanical behaviors of deep rock mass are different from those of shallow rock mass.Through cases of Jinping II Hydropower Station,the special phenomenon of zonal disintegration in the surrounding rock mass around the diversion tunnels,is analyzed.On the basis of fracture mechanics,a new strength criterion for deep rock mass is derived.The new nonlinear strength criterion that is relative to the rock mass rating classification can be applied to the study of the tensile failure of deep rock mass.Subsequently,zonal disintegration model is established,and the radius of fractured zone and none-fractured zone of deep surrounding rock mass around cylindrical tunnel are obtained,their exact positions and the evolution law of zonal disintegration of surrounding rock mass is determined.To validate the present model,comparison between calculation results and the experiment observation on facture and failure around underground openings is carried out.It is found that the numerical simulation result is in good agreement with the experimental one on failure modes around the hole.Through sensitivity analysis,the effects of stress condition,cohesion and the angle of internal friction on the phenomenon of zonal disintegration are determined.Finally,the present model is adopted in the analysis of the zonal disintegration in the surrounding rock mass around the diversion tunnels in Jinping II Hydropower Station.Meanwhile,the magnitude and distributions of fractured zones are determined by numerical simulation.

  5. Buoyancy storms in a zonal stream on the polar beta-plane: experiments with altimetry

    CERN Document Server

    Sui, Yi

    2013-01-01

    Results from a new series of experiments on flows generated by localized heating in the presence of a background zonal current on the polar beta-plane are presented. The flow induced by a heater without the background zonal flow is in the form of a beta-plume. Zonal jets of alternating directions are formed within the plume. The westward transport velocity in the plume is proportional to the upwelling velocity above the heater in agreement with linear theory. When the background flow in the form of the eastward zonal current is present, the beta-plume can be overwhelmed by the eastward current. The main control parameters of the experiment are the strength of the heater and strength of the sink which is used to create the background flow. The regime diagram shows the area where a beta-plume can exist in the parameter space. The critical value of the velocity of the zonal flow below which the beta-plume can exist is obtained by considering barotropic Rossby waves emitted by the baroclinic eddies in the heated ...

  6. The role of zonal flows in the saturation of multi-scale gyrokinetic turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Staebler, G. M.; Candy, J. [General Atomics, San Diego, California 92186 (United States); Howard, N. T. [Oak Ridge Institute for Science Education (ORISE), Oak Ridge, Tennessee 37831 (United States); Holland, C. [University of California San Diego, San Diego, California 92093 (United States)

    2016-06-15

    The 2D spectrum of the saturated electric potential from gyrokinetic turbulence simulations that include both ion and electron scales (multi-scale) in axisymmetric tokamak geometry is analyzed. The paradigm that the turbulence is saturated when the zonal (axisymmetic) ExB flow shearing rate competes with linear growth is shown to not apply to the electron scale turbulence. Instead, it is the mixing rate by the zonal ExB velocity spectrum with the turbulent distribution function that competes with linear growth. A model of this mechanism is shown to be able to capture the suppression of electron-scale turbulence by ion-scale turbulence and the threshold for the increase in electron scale turbulence when the ion-scale turbulence is reduced. The model computes the strength of the zonal flow velocity and the saturated potential spectrum from the linear growth rate spectrum. The model for the saturated electric potential spectrum is applied to a quasilinear transport model and shown to accurately reproduce the electron and ion energy fluxes of the non-linear gyrokinetic multi-scale simulations. The zonal flow mixing saturation model is also shown to reproduce the non-linear upshift in the critical temperature gradient caused by zonal flows in ion-scale gyrokinetic simulations.

  7. Predicting Zonal Flows -- A Comprehensive Reynolds-Stress Response-Functional from First-Principles-Plasma-Turbulence Computations

    CERN Document Server

    Guertler, Niels

    2011-01-01

    Turbulence driven zonal flows play an important role in fusion devices since they improve plasma confinement by limiting the level of anomalous transport. Current theories mostly focus on flow excitation but do not self-consistently describe the nearly stationary zonal flow turbulence equilibrium state. First-principles two-fluid turbulence studies are used to construct a Reynolds stress response functional from observations in turbulent states. This permits, for the first time, a reliable charting of zonal flow turbulence equilibria.

  8. Wave optics-based LEO-LEO radio occultation retrieval

    Science.gov (United States)

    Benzon, Hans-Henrik; Høeg, Per

    2016-06-01

    This paper describes the theory for performing retrieval of radio occultations that use probing frequencies in the XK and KM band. Normally, radio occultations use frequencies in the L band, and GPS satellites are used as the transmitting source, and the occultation signals are received by a GPS receiver on board a Low Earth Orbit (LEO) satellite. The technique is based on the Doppler shift imposed, by the atmosphere, on the signal emitted from the GPS satellite. Two LEO satellites are assumed in the occultations discussed in this paper, and the retrieval is also dependent on the decrease in the signal amplitude caused by atmospheric absorption. The radio wave transmitter is placed on one of these satellites, while the receiver is placed on the other LEO satellite. One of the drawbacks of normal GPS-based radio occultations is that external information is needed to calculate some of the atmospheric products such as the correct water vapor content in the atmosphere. These limitations can be overcome when a proper selected range of high-frequency waves are used to probe the atmosphere. Probing frequencies close to the absorption line of water vapor have been included, thus allowing the retrieval of the water vapor content. Selecting the correct probing frequencies would make it possible to retrieve other information such as the content of ozone. The retrieval is performed through a number of processing steps which are based on the Full Spectrum Inversion (FSI) technique. The retrieval chain is therefore a wave optics-based retrieval chain, and it is therefore possible to process measurements that include multipath. In this paper simulated LEO to LEO radio occultations based on five different frequencies are used. The five frequencies are placed in the XK or KM frequency band. This new wave optics-based retrieval chain is used on a number of examples, and the retrieved atmospheric parameters are compared to the parameters from a global European Centre for Medium

  9. Dynamics of zonal flow-like structures in the edge of the TJ-II stellarator

    CERN Document Server

    Alonso, J A; Arévalo, J; Hidalgo, C; Pedrosa, M A; Van Milligen, B Ph; Carralero, D

    2012-01-01

    The dynamics of fluctuating electric field structures in the edge of the TJ-II stellarator, that display zonal flow-like traits, is studied. These structures have been shown to be global and affect particle transport dynamically [J.A. Alonso et al., Nucl. Fus. 52 063010 (2012)]. In this article we discuss possible drive (Reynolds stress) and damping (Neoclassical viscosity, geodesic transfer) mechanisms for the associated ExB velocity. We show that: (a) while the observed turbulence-driven forces can provide the necessary perpendicular acceleration, a causal relation could not be firmly established, possibly because of the locality of the Reynolds stress measurements, (b) the calculated neoclassical viscosity and damping times are comparable to the observed zonal flow relaxation times, and (c) although an accompanying density modulation is observed to be associated to the zonal flow, it is not consistent with the excitation of pressure side-bands, like those present in geodesic acoustic oscillations, caused b...

  10. High spatial resolution zonal wavefront reconstruction with improved initial value determination scheme for lateral shearing interferometry.

    Science.gov (United States)

    Dai, Fengzhao; Tang, Feng; Wang, Xiangzhao; Sasaki, Osami; Zhang, Min

    2013-06-10

    In a recent paper [J. Opt. Soc. Am. A 29, 2038 (2012)], we proposed a generalized high spatial resolution zonal wavefront reconstruction method for lateral shearing interferometry. The test wavefront can be reconstructed with high spatial resolution by using linear interpolation on a subgrid for initial values estimation. In the current paper, we utilize the difference between the Zernike polynomial fitting method and linear interpolation in determining the subgrid initial values. The validity of the proposed method is investigated through comparison with the previous high spatial resolution zonal method. Simulation results show that the proposed method is more accurate and more stable to shear ratios compared with the previous method. A comprehensive comparison of the properties of the proposed method, the previous high spatial resolution zonal method, and the modal method is performed.

  11. Eddy, drift wave and zonal flow dynamics in a linear magnetized plasma

    Science.gov (United States)

    Arakawa, H.; Inagaki, S.; Sasaki, M.; Kosuga, Y.; Kobayashi, T.; Kasuya, N.; Nagashima, Y.; Yamada, T.; Lesur, M.; Fujisawa, A.; Itoh, K.; Itoh, S.-I.

    2016-09-01

    Turbulence and its structure formation are universal in neutral fluids and in plasmas. Turbulence annihilates global structures but can organize flows and eddies. The mutual-interactions between flow and the eddy give basic insights into the understanding of non-equilibrium and nonlinear interaction by turbulence. In fusion plasma, clarifying structure formation by Drift-wave turbulence, driven by density gradients in magnetized plasma, is an important issue. Here, a new mutual-interaction among eddy, drift wave and flow in magnetized plasma is discovered. A two-dimensional solitary eddy, which is a perturbation with circumnavigating motion localized radially and azimuthally, is transiently organized in a drift wave - zonal flow (azimuthally symmetric band-like shear flows) system. The excitation of the eddy is synchronized with zonal perturbation. The organization of the eddy has substantial impact on the acceleration of zonal flow.

  12. Zonal flow generation and its feedback on turbulence production in drift wave turbulence

    CERN Document Server

    Pushkarev, Andrey V; Nazarenko, Sergey V

    2012-01-01

    Plasma turbulence described by the Hasegawa-Wakatani equations has been simulated numerically for different models and values of the adiabaticity parameter C. It is found that for low values of C turbulence remains isotropic, zonal flows are not generated and there is no suppression of the meridional drift waves and of the particle transport. For high values of C, turbulence evolves toward highly anisotropic states with a dominant contribution of the zonal sector to the kinetic energy. This anisotropic flow leads to a decrease of a turbulence production in the meridional sector and limits the particle transport across the mean isopycnal surfaces. This behavior allows to consider the Hasegawa-Wakatani equations a minimal PDE model which contains the drift-wave/zonal-flow feedback loop prototypical of the LH transition in plasma devices.

  13. Periodical zonal character of damage near the openings in highly-stressed rock mass conditions

    Directory of Open Access Journals (Sweden)

    Vladimir V. Makarov

    2016-04-01

    Full Text Available Rock mass damage at great depths near underground openings is often of a zonal character. However, the classical elastoplastic theory fails to explain sufficiently all properties of zonal failure structures. A new non-Euclidean mathematical model for highly-stressed rock mass was developed based on the principles of mechanics of defected material and non-equilibrium thermodynamics. Methods were developed to determine model parameters that provide satisfactory correspondence between the experimental findings concerning faulted zonal structures near openings at great depths and mathematical calculations. The mechanism of this phenomenon was discovered which consisted in a periodical character of stresses in the surrounding rock mass and development of tensile macrocracks at zones of maximal tangential stresses. Main relationships between the cracking zone width and rock mass strength were established.

  14. Experimental study of libration-driven zonal flows in non-axisymmetric containers

    CERN Document Server

    Noir, Jerome; Bars, Michael Le; Sauret, Alban; Aurnou, J M; 10.1016/j.pepi.2012.05.005

    2013-01-01

    Orbital dynamics that lead to longitudinal libration of celestial bodies also result in an elliptically deformed equatorial core-mantle boundary. The non-axisymmetry of the boundary leads to a topographic coupling between the assumed rigidmantle and the underlying low viscosity fluid.The present experimental study investigates theeffect of non axisymmetric boundaries on the zonal flow driven by longitudinal libration. For large enough equatorial ellipticity, we report intermittent space-filling turbulence in particular bands of resonant frequency correlated with larger amplitude zonal flow. The mechanism underlying the intermittent turbulence has yet to be unambiguously determined. Nevertheless, recent numerical simulations in triaxial and biaxial ellipsoids suggest that it may be associated with the growth and collapse of an elliptical instability (Cebron et al., 2012). Outside of the band of resonance, we find that the background flow is laminar and the zonal flow becomes independent of the geometry at firs...

  15. Collisional Scaling of the Energy Transfer in Drift-Wave Zonal Flow Turbulence.

    Science.gov (United States)

    Schmid, B; Manz, P; Ramisch, M; Stroth, U

    2017-02-03

    The collisionality scaling of density and potential coupling together with zonal flow energy transfer and spectral power is investigated at the stellarator experiment TJ-K. With a poloidal probe array, consisting of 128 Langmuir probes, density and potential fluctuations are measured on four neighboring flux surfaces simultaneously over the complete poloidal circumference. By analyzing Reynolds stress and pseudo-Reynolds stress, it is found that, for increasing collisionality, the coupling between density and potential decreases which hinders the zonal flow drive. Also, as a consequence, the nonlinear energy transfer, as well as the zonal flow contribution to the complete turbulent spectrum, decreases the same way. This is in line with theoretical expectations and is a first experimental verification of the importance of collisionality for large-scale structure formation in magnetically confined toroidal plasmas.

  16. New temperature and pressure retrieval algorithm for high-resolution infrared solar occultation spectroscopy: analysis and validation against ACE-FTS and COSMIC

    Directory of Open Access Journals (Sweden)

    K. S. Olsen

    2015-10-01

    Full Text Available Motivated by the initial selection of a high-resolution solar occultation Fourier transform spectrometer (FTS to fly to Mars on the ExoMars Trace Gas Orbiter, we have been developing algorithms for retrieving volume mixing ratio vertical profiles of trace gases, the primary component of which is a new algorithm and software for retrieving vertical profiles of temperature and pressure from the spectra. In contrast to Earth-observing instruments, which can rely on accurate meteorological models, a priori information, and spacecraft position, Mars retrievals require a method with minimal reliance on such data. The temperature and pressure retrieval algorithms developed for this work were evaluated using Earth-observing spectra from the Atmospheric Chemistry Experiment (ACE FTS, a solar occultation instrument in orbit since 2003, and the basis for the instrument selected for a Mars mission. ACE-FTS makes multiple measurements during an occultation, separated in altitude by 1.5–5 km, and we analyze 10 CO2 vibration-rotation bands at each altitude, each with a different usable altitude range. We describe the algorithms and present results of their application and their comparison to the ACE-FTS data products. The Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC provides vertical profiles of temperature up to 40 km with high vertical resolution. Using six satellites and GPS radio occultation, COSMIC's data product has excellent temporal and spatial coverage, allowing us to find coincident measurements with ACE with very tight criteria: less than 1.5 h and 150 km. We present an inter-comparison of temperature profiles retrieved from ACE-FTS using our algorithm, that of the ACE Science Team (v3.5, and from COSMIC. When our retrievals are compared to ACE-FTS v3.5, we find mean differences between −5 and +2 K, and that our retrieved profiles have no seasonal or zonal biases, but do have a warm bias in the stratosphere and

  17. Error analysis for mesospheric temperature profiling by absorptive occultation sensors

    Directory of Open Access Journals (Sweden)

    M. J. Rieder

    Full Text Available An error analysis for mesospheric profiles retrieved from absorptive occultation data has been performed, starting with realistic error assumptions as would apply to intensity data collected by available high-precision UV photodiode sensors. Propagation of statistical errors was investigated through the complete retrieval chain from measured intensity profiles to atmospheric density, pressure, and temperature profiles. We assumed unbiased errors as the occultation method is essentially self-calibrating and straight-line propagation of occulted signals as we focus on heights of 50–100 km, where refractive bending of the sensed radiation is negligible. Throughout the analysis the errors were characterized at each retrieval step by their mean profile, their covariance matrix and their probability density function (pdf. This furnishes, compared to a variance-only estimation, a much improved insight into the error propagation mechanism. We applied the procedure to a baseline analysis of the performance of a recently proposed solar UV occultation sensor (SMAS – Sun Monitor and Atmospheric Sounder and provide, using a reasonable exponential atmospheric model as background, results on error standard deviations and error correlation functions of density, pressure, and temperature profiles. Two different sensor photodiode assumptions are discussed, respectively, diamond diodes (DD with 0.03% and silicon diodes (SD with 0.1% (unattenuated intensity measurement noise at 10 Hz sampling rate. A factor-of-2 margin was applied to these noise values in order to roughly account for unmodeled cross section uncertainties. Within the entire height domain (50–100 km we find temperature to be retrieved to better than 0.3 K (DD / 1 K (SD accuracy, respectively, at 2 km height resolution. The results indicate that absorptive occultations acquired by a SMAS-type sensor could provide mesospheric profiles of fundamental variables such as temperature with

  18. Probing Pluto's Atmosphere Using Ground-Based Stellar Occultations

    Science.gov (United States)

    Sicardy, Bruno; Rio de Janeiro Occultation Team, Granada Team, International Occultation and Timing Association, Royal Astronomical Society New Zealand Occultation Section, Lucky Star associated Teams

    2016-10-01

    Over the last three decades, some twenty stellar occultations by Pluto have been monitored from Earth. They occur when the dwarf planet blocks the light from a star for a few minutes as it moves on the sky. Such events led to the hint of a Pluto's atmosphere in 1985, that was fully confirmed during another occultation in 1988, but it was only in 2002 that a new occultation could be recorded. From then on, the dwarf planet started to move in front of the galactic center, which amplified by a large factor the number of events observable per year.Pluto occultations are essentially refractive events during which the stellar rays are bent by the tenuous atmosphere, causing a gradual dimming of the star. This provides the density, pressure and temperature profiles of the atmosphere from a few kilometers above the surface up to about 250 km altitude, corresponding respectively to pressure levels of about 10 and 0.1 μbar. Moreover, the extremely fine spatial resolution (a few km) obtained through this technique allows the detection of atmospheric gravity waves, and permits in principle the detection of hazes, if present.Several aspects make Pluto stellar occultations quite special: first, they are the only way to probe Pluto's atmosphere in detail, as the dwarf planet is far too small on the sky and the atmosphere is far too tenuous to be directly imaged from Earth. Second, they are an excellent example of participative science, as many amateurs have been able to record those events worldwide with valuable scientific returns, in collaboration with professional astronomers. Third, they reveal Pluto's climatic changes on decade-scales and constrain the various seasonal models currently explored.Finally, those observations are fully complementary to space exploration, in particular with the New Horizons (NH) mission. I will show how ground-based occultations helped to better calibrate some NH profiles, and conversely, how NH results provide some key boundary conditions

  19. Is Occult Obscure Gastrointestinal Bleeding a Definite Indication for Capsule Endoscopy? A Retrospective Analysis of Diagnostic Yield in Patients with Occult versus Overt Bleeding

    Directory of Open Access Journals (Sweden)

    Ikue Watari

    2013-01-01

    Full Text Available Background/Aim. Usefulness of capsule endoscopy (CE for diagnosing small-bowel lesions in patients with obscure gastrointestinal bleeding (OGIB has been reported. Most reports have addressed the clinical features of overt OGIB, with few addressing occult OGIB. We aimed to clarify whether occult OGIB is a definite indication for CE. Methods. We retrospectively compared the cases of 102 patients with occult OGIB and 325 patients with overt OGIB, all having undergone CE. The diagnostic yield of CE and identification of various lesion types were determined in cases of occult OGIB versus overt OGIB. Results. There was no significant difference in diagnostic yield between occult and overt OGIB. The small-bowel lesions in cases of occult OGIB were diagnosed as ulcer/erosive lesions (n=18, 18%, vascular lesions (n=11, 11%, and tumors (n=4, 3%, and those in cases of overt OGIB were diagnosed as ulcer/erosive lesions (n=51, 16%, vascular lesions (n=31, 10%, and tumors (n=20, 6%. Conclusion. CE detection rates and CE identification of various small-bowel diseases do not differ between patients with occult versus overt OGIB. CE should be actively performed for patients with either occult or overt OGIB.

  20. Is Occult Obscure Gastrointestinal Bleeding a Definite Indication for Capsule Endoscopy? A Retrospective Analysis of Diagnostic Yield in Patients with Occult versus Overt Bleeding.

    Science.gov (United States)

    Watari, Ikue; Oka, Shiro; Tanaka, Shinji; Nakano, Makoto; Aoyama, Taiki; Yoshida, Shigeto; Chayama, Kazuaki

    2013-01-01

    Background/Aim. Usefulness of capsule endoscopy (CE) for diagnosing small-bowel lesions in patients with obscure gastrointestinal bleeding (OGIB) has been reported. Most reports have addressed the clinical features of overt OGIB, with few addressing occult OGIB. We aimed to clarify whether occult OGIB is a definite indication for CE. Methods. We retrospectively compared the cases of 102 patients with occult OGIB and 325 patients with overt OGIB, all having undergone CE. The diagnostic yield of CE and identification of various lesion types were determined in cases of occult OGIB versus overt OGIB. Results. There was no significant difference in diagnostic yield between occult and overt OGIB. The small-bowel lesions in cases of occult OGIB were diagnosed as ulcer/erosive lesions (n = 18, 18%), vascular lesions (n = 11, 11%), and tumors (n = 4, 3%), and those in cases of overt OGIB were diagnosed as ulcer/erosive lesions (n = 51, 16%), vascular lesions (n = 31, 10%), and tumors (n = 20, 6%). Conclusion. CE detection rates and CE identification of various small-bowel diseases do not differ between patients with occult versus overt OGIB. CE should be actively performed for patients with either occult or overt OGIB.

  1. Association of preS/S Mutations with Occult Hepatitis B Virus (HBV Infection in South Korea: Transmission Potential of Distinct Occult HBV Variants

    Directory of Open Access Journals (Sweden)

    Hong Kim

    2015-06-01

    Full Text Available Occult hepatitis B virus infection (HBV is characterized by HBV DNA positivity but HBV surface antigen (HBsAg negativity. Occult HBV infection is associated with a risk of HBV transmission through blood transfusion, hemodialysis, and liver transplantation. Furthermore, occult HBV infection contributes to the development of cirrhosis and hepatocellular carcinoma. We recently reported the characteristic molecular features of mutations in the preS/S regions among Korean individuals with occult infections caused by HBV genotype C2; the variants of preS and S related to severe liver diseases among chronically infected patients were also responsible for the majority of HBV occult infections. We also reported that HBsAg variants from occult-infected Korean individuals exhibit lower HBsAg secretion capacity but not reduced HBV DNA levels. In addition, these variants exhibit increased ROS-inducing capacity compared with the wild-type strain, linking HBV occult infections to liver cell damage. Taken together, our previous reports suggest the transmission potential of distinct HBV occult infection-related variants in South Korea.

  2. Association of preS/S Mutations with Occult Hepatitis B Virus (HBV) Infection in South Korea: Transmission Potential of Distinct Occult HBV Variants.

    Science.gov (United States)

    Kim, Hong; Kim, Bum-Joon

    2015-06-15

    Occult hepatitis B virus infection (HBV) is characterized by HBV DNA positivity but HBV surface antigen (HBsAg) negativity. Occult HBV infection is associated with a risk of HBV transmission through blood transfusion, hemodialysis, and liver transplantation. Furthermore, occult HBV infection contributes to the development of cirrhosis and hepatocellular carcinoma. We recently reported the characteristic molecular features of mutations in the preS/S regions among Korean individuals with occult infections caused by HBV genotype C2; the variants of preS and S related to severe liver diseases among chronically infected patients were also responsible for the majority of HBV occult infections. We also reported that HBsAg variants from occult-infected Korean individuals exhibit lower HBsAg secretion capacity but not reduced HBV DNA levels. In addition, these variants exhibit increased ROS-inducing capacity compared with the wild-type strain, linking HBV occult infections to liver cell damage. Taken together, our previous reports suggest the transmission potential of distinct HBV occult infection-related variants in South Korea.

  3. Zonal character of failure near the wells and openings in high depth conditions

    Institute of Scientific and Technical Information of China (English)

    V.V. Makarov; L.S. Ksendzenko; V.M. Sapelkina; A.A. Opanasyuk; N.A. Opanasyuk; E.N. Jashkova

    2006-01-01

    Rock mass failure on the high depth near the underground openings often has zonal character. The mechanism of this phenomenon consists in the periodical character of stresses in surrounding rock mass and developing of tensile macrocracks at the places (zones) of maximum tangentional stresses. Mathematical model of the high stressed rock mass is developed on the base of the defect media mechanics and nonequilibrium thermodynamics principals. The correspondence between the experimental research of faulted zonal structures near the high depths openings and mathematical model calculation is achieved. Relationships between the width of cracking zones and rock mass strength property have been determined.

  4. Role of CT in patients with prostatic disease; Usefulness of depiction of prostatic zonal anatomy

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizako, Takeshi; Sugimura, Kazuro; Kaji, Yasushi; Moriyama, Masahiro; Ishida, Tetsuya (Shimane Medical Univ., Izumo (Japan))

    1994-05-01

    The purpose of this study was to evaluate the role of CT in patients with and without prostatic disease. CT and MR findings were reviewed in 25 patients without known prostatic disease, 11 patients with benign prostatic hyperplasia and 11 patients with prostatic cancer. Differential attenuation allowed for distinction of the peripheral zone and inner gland of the prostate by CT in 72% of normal patients. The distinction rate of prostatic zonal anatomy by CT decreased to 30% in the diseased group. When zonal anatomy of the prostate is not visualized on pelvic enhanced CT, the presence of prostatic disease might be considered. (author).

  5. Intragraft vascular occlusive sickle crisis with early renal allograft loss in occult sickle cell trait.

    Science.gov (United States)

    Kim, Lisa; Garfinkel, Marc R; Chang, Anthony; Kadambi, Pradeep V; Meehan, Shane M

    2011-07-01

    Early renal allograft failure due to sickle cell trait is rare. We present clinical and pathologic findings in 2 cases of early renal allograft failure associated with renal vein thrombosis and extensive erythrocyte sickling. Hemoglobin AS was identified in retrospect. In case 1, a 41-year-old female recipient of a deceased donor renal transplant developed abdominal pain and acute allograft failure on day 16, necessitating immediate nephrectomy. In case 2, the transplanted kidney in a 58-year-old female recipient was noted to be mottled blue within minutes of reperfusion. At 24 hours, the patient was oliguric; and the graft was removed. Transplant nephrectomies had diffuse enlargement with diffuse, nonhemorrhagic, cortical, and medullary necrosis. Extensive sickle vascular occlusion was evident in renal vein branches; interlobar, interlobular, and arcuate veins; vasa recta; and peritubular capillaries. The renal arteries had sickle vascular occlusion in case 1. Glomeruli had only focal sickle vascular occlusion. The erythrocytes in sickle vascular occlusion had abundant cytoplasmic filaments by electron microscopy. Acute rejection was not identified in either case. Protein C and S levels, factor V Leiden, and lupus anticoagulant assays were within normal limits. Hemoglobin analysis revealed hemoglobin S of 21.8% and 25.6%, respectively. Renal allograft necrosis with intragraft sickle crisis, characterized by extensive vascular occlusive erythrocyte sickling and prominent renal vein thrombosis, was observed in 2 patients with sickle cell trait. Occult sickle cell trait may be a risk factor for early renal allograft loss.

  6. Titan's haze as seen by VIMS during solar occultation observations

    Science.gov (United States)

    Sotin, Christophe; Lawrence, Ken; Xu, Fang; West, Robert; Brown, Robert; Baines, Kevin; Buratti, Bonnie; Clark, Roger; Micholson, Phil

    2016-06-01

    This study describe solar occultation observations of Titan's atmosphere by the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft. These observations include two recent observations made in the last few months. The solar occultation observations have been made at different latitudes and seasons, which allows us to investigate the variability of the density profile of aerosols. We present the line curves in the different atmospheric windows, and the data processing and the inversion method to retrieve vertical density profile. This unique data set provides information on Titan's opacity in the atmospheric windows, which is important to retrieve the surface properties. It also provides information on the cross-subsection of the aerosols as a function of wavelength in the wavelength range 1 to 5 micron.

  7. Detection of occult disease in tissue donors by routine autopsy.

    Science.gov (United States)

    Otero, J; Fresno, M F; Escudero, D; Seco, M; González, M; Peces, R

    1998-01-01

    The transmission of infectious and neoplastic diseases is a potential risk of tissue allografting. In this study, we analyzed the occurrence of occult disease in tissue donors as detected by standard screening and autopsy. Whereas 18% of the potential donors initially evaluated were eliminated on the basis of their medical and social histories, laboratory screening and autopsy revealed that an additional 9% of tissue donors had undetected, transmissible disease that prohibited tissue donation. This report emphasizes once again the risk of occult disease being transplanted with grafts and the need for autopsy to reduce the likelihood of this occurring. If donor selection, appropriate screening tests, and autopsy are carefully carried out, the risk of transmitting diseases from tissue allografts can be kept to a minimum.

  8. Status of the Transneptunian Automated Occultation Survey (TAOS II)

    Science.gov (United States)

    Reyes-Ruiz, Mauricio

    2014-11-01

    TAOS II is a next generation occultation survey with the goal of measuring the size distribution of the small objects (diameters between 0.5 and 30 km) in the Kuiper Belt. The project is a collaboration between the Academia Sinica Institute of Astronomy and Astrophysics, the Universidad Nacional Autonoma de Mexico, and the Harvard-Smithsonian Center for Astrophysics, The survey will operate three 1.3 m telescopes at San Pedro Martir Observatory in Baja California, Mexico. Each telescope will be equipped with a custom camera comprising a focal plane array of CMOS imagers. Each camera will be capable of reading out image data from 10,000 stars at a cadence of 20 Hz. All telescopes will monitor the same set of stars simultaneously to search for coincident occultation events while minimizing the false positive rate. This poster describes the project and reports on the progress of the development of the survey infrastructure.

  9. Externally Occulted Terrestrial Planet Finder Coronagraph: Simulations and Sensitivities

    CERN Document Server

    Lyon, Richard G; Lo, Amy; Cash, Webster; Starkman, Glenn D; Vanderbei, Robert J; Kasdin, N Jeremy; Copi, Craig J

    2007-01-01

    A multitude of coronagraphic techniques for the space-based direct detection and characterization of exo-solar terrestrial planets are actively being pursued by the astronomical community. Typical coronagraphs have internal shaped focal plane and/or pupil plane occulting masks which block and/or diffract starlight thereby increasing the planet's contrast with respect to its parent star. Past studies have shown that any internal technique is limited by the ability to sense and control amplitude, phase (wavefront) and polarization to exquisite levels - necessitating stressing optical requirements. An alternative and promising technique is to place a starshade, i.e. external occulter, at some distance in front of the telescope. This starshade suppresses most of the starlight before entering the telescope - relaxing optical requirements to that of a more conventional telescope. While an old technique it has been recently been advanced by the recognition that circularly symmetric graded apodizers can be well appro...

  10. An overview of occult hepatitis B virus infection

    Institute of Scientific and Technical Information of China (English)

    Zeinab Nabil Ahmed Said

    2011-01-01

    Occult hepatitis B virus (HBV) infection (OBI), alternatively defined as occult hepatitis B (OHB), is a challenging clinical entity. It is recognized by two main characteristics: absence of HBsAg, and low viral replication. The previous two decades have witnessed a remarkable progress in our nderstanding of OBI and its clinical implications. Appropriate diagnostic techniques must be adopted. Sensitive HBV DNA amplification assay is the gold standard assay for detection of OBI. Viral as well as host factors are implicated in the pathogenesis of OBI. However, published data reporting the infectivity of OBI by transfusion are limited. Several aspects including OBI transmission, infectivity and its relation to the development of chronic liver diseases and hepatocellular carcinoma have to be resolved. The aim of the present review is to highlight recent data on OBI with a focus on its virological diagnosis and clinical outcome.

  11. New insights to occult gastrointestinal bleeding: From pathophysiology to therapeutics

    Institute of Scientific and Technical Information of China (English)

    Antonio; Damián; Sánchez-Capilla; Paloma; De; La; Torre-Rubio; Eduardo; Redondo-Cerezo

    2014-01-01

    Obscure gastrointestinal bleeding is still a clinical challenge for gastroenterologists. The recent development of novel technologies for the diagnosis and treatment of different bleeding causes has allowed a better management of patients, but it also determines the need of a deeper comprehension of pathophysiology and the analysis of local expertise in order to develop a rational management algorithm. Obscure gastrointestinal bleeding can be divided in occult, when a positive occult blood fecal test is the main manifestation, and overt, when external sings of bleeding are visible. In this paper we are going to focus on overt gastrointestinal bleeding, describing the physiopathology of the most usual causes, analyzing the diagnostic procedures available, from the most classical to the novel ones, and establishing a standard algorithm which can be adapted depending on the local expertise or availability. Finally, we will review the main therapeutic options for this complex and not so uncommon clinical problem.

  12. Wave Optics Based LEO-LEO Radio Occultation Retrieval

    DEFF Research Database (Denmark)

    von Benzon, Hans-Henrik; Høeg, Per

    2016-01-01

    in the signal amplitude caused by atmospheric absorption. The radio wave transmitter is placed on one of these satellites while the receiver is placed on the other LEO satellite. One of the drawbacks of normal GPS based radio occultations is that external information is needed to calculate some...... of the atmospheric products such as the correct water vapor content in the atmosphere. These limitations can be overcome when a proper selected range of high frequency waves are used to probe the atmosphere. Probing frequencies close to the absorption line of water vapor have been included, thus allowing...... chain is therefore a wave optics based retrieval chain and it is therefore possible to process measurements that include multipath. In this paper simulated LEO to LEO radio occultations based on 5 different frequencies are used. The 5 frequencies are placed in the XK or KM frequency band. This new wave...

  13. Pneumonitis associated with occult heartworm disease in dogs.

    Science.gov (United States)

    Calvert, C A; Losonsky, J M

    1985-05-15

    Nine of 69 dogs with occult heartworm disease (13%) had allergic pneumonitis characterized by consistent clinical and radiographic signs. Although the clinical signs were severe, the degree of radiographic pulmonary arterial abnormalities was mild. Corticosteroid therapy resulted in rapid resolution of clinical and radiographic signs; thiacetarsamide therapy was then given without complications. This syndrome may not be recognized as heartworm-associated and may be confused with other disorders, some being associated with a poor prognosis and requiring different therapy.

  14. Occult Hepatitis C Virus Infection among Hemodialysis Patients

    OpenAIRE

    G. Barril; Castillo, I.; Arenas, M.D. (María Dolores); Espinosa, M; Garcia-Valdecasas, J. (Juan); Garcia-Fernandez, N. (Nuria); E Gonzalez-Parra; Alcazar, J.M. (José María); Sanchez, C.; Diez-Baylon, J.C. (José Carlos); P. MARTINEZ; Bartolome, J; Carreño, V

    2008-01-01

    Occult hepatitis C virus (HCV) infection (i.e., detectable HCV-RNA in the liver or peripheral blood mononuclear cells) in the absence of both serum HCV-RNA and anti-HCV antibodies has not been investigated in hemodialysis patients. In this study, real-time PCR and in situ hybridization was used to test for the presence of genomic and antigenomic HCV-RNA in peripheral blood mononuclear cells of 109 hemodialysis patients with abnormal levels of live...

  15. Analyses for a Modernized GNSS Radio Occultation Receiver

    Science.gov (United States)

    Griggs, Erin R.

    Global Navigation Satellite System (GNSS) radio occultation (RO) is a remote sensing technique that exploits existing navigation signals to make global, real-time observations of the Earth's atmosphere. A specialized RO receiver makes measurements of signals originating from a transmitter onboard a GNSS spacecraft near the Earth's horizon. The radio wave is altered during passage through the Earth's atmosphere. The changes in the received signals are translated to the refractivity characteristics of the intervening medium, which enable the calculation of atmospheric pressure, temperature, and humidity. Current satellite missions employing GNSS RO have provided invaluable and timely information for weather and climate applications. Existing constellations of occultation satellites, however, are aging and producing fewer quality measurements. Replacement fleets of RO satellites are imperative to sustain and improve the global coverage and operational impact achieved by the current generation of RO satellites. This dissertation describes studies that facilitate the development of next generation RO receivers and satellite constellations. Multiple research efforts were conducted that aim to improve the quantity and quality of measurements made by a future satellite-based RO collection system. These studies range in magnitude and impact, and begin with a receiver development study using ground-based occultation data. Future RO constellations and collection opportunities were simulated and autonomous occultation prediction and scheduling capabilities were implemented. Finally, a comprehensive study was conducted to characterize the stability of the GNSS atomic frequency standards. Oscillator stability for a subset of satellites in the GNSS was found to be of insufficient quality at timescales relevant to RO collections and would degrade the atmospheric profiling capabilities of an RO system utilizing these signals. Recommendations for a high-rate clock correction network

  16. PREVALENCE OF OCCULT DEPRESSION IN ELDERLY WITH CHRONIC CO - MORBIDS

    OpenAIRE

    Sachin; Anand Ambali; Shashikant

    2015-01-01

    BACKGROUND: Growth in elderly population has led to an increase in age related diseases and mainly depression which is affecting the quality of life. Depression is more prevalent amongst elderly individuals with medical illnesses and emerging public health problem leading to increased morbidity and disability worldwide. AIMS AND OBJE CTIVES: To assess the prevalence of occult depression in elderly patients with chronic co - morbid medi...

  17. Implementation of immunochemical faecal occult blood test in general practice

    DEFF Research Database (Denmark)

    Juul, Jakob Søgaard; Bro, Flemming; Hornung, Nete

    2016-01-01

    anvendelsen af immunochemical faecal occult blood test (iFOBT) i almen praksis. iFOBT detekterer humant globin i fæces og indikerer gastrointestinal blødning. Studiet udgør en del af et ph.d.-studie, der bidrager med ny viden til at optimere udredningen af patienter med tarmkræft. Der er et stort behov...

  18. Occult persistence and lymphotropism of hepatitis C virus infection

    Institute of Scientific and Technical Information of China (English)

    Tram NQ Pham; Tomasz I Michalak

    2008-01-01

    Recent discovery of occult hepatitis C virus (HCV)infection persisting after spontaneous or antiviral therapy-induced resolution of hepatitis C was made possible by the introduction of nucleic acid amplification assays capable of detecting HCV RNA at sensitivities superseding those offered by clinical tests. Although individuals with this seemingly silent HCV infection are usually anti-HCV antibody reactive and have normal liver function tests, occult HCV infection has also been reported in anti-HCV-negative individuals with persistently elevated liver enzymes of unknown etiology. Studies have shown that HCV RNA can persist for years in serum, iymphomononuciear cells and liver in the absence of clinical symptoms, although histological evidence of a mild inflammatory liver injury can be occasionally encountered. Furthermore, while HCV RNA can be detected in circulating lymphoid cells in approximately 30% of cases, a short-term culture under stimulatory conditions augments HCV replication in these cells allowing detection of virus in otherwise HCV-negative cases. HCV infects different immune cell subsets, including CD4+ and CD8+ T lymphocytes, B cells and monocytes. Studies employing cional sequencing and single-stranded conformational polymorphism analyses have revealed unique HCV variants residing in immune cells, further strengthening the notion of HCV lymphotropism. Overall, the data accumulated suggest that occult HCV infection is a common consequence of resolution of symptomatic hepatitis C and that examination of the cells of the immune system is an effective approach to diagnosis of HCV infection and its long-term persistence. Further work is required to fully realize pathogenic and epidemiological consequences of occult HCV persistence.

  19. All-Sky Earth Occultation Observations with the Fermi Gamma Ray Burst Monitor

    CERN Document Server

    Wilson-Hodge, Colleen A; Bhat, P N; Briggs, M S; Chaplin, V; Connaughton, V; Camero-Arranz, A; Case, G; Cherry, M; Rodi, J; Finger, M H; Jenke, P; Haynes, R H

    2009-01-01

    Using the Gamma Ray Burst Monitor (GBM) on-board Fermi, we are monitoring the hard X-ray/soft gamma ray sky using the Earth occultation technique. Each time a source in our catalog enters or exits occultation by the Earth, we measure its flux using the change in count rates due to the occultation. Currently we are using CTIME data with 8 energy channels spanning 8 keV to 1 MeV for the GBM NaI detectors and spanning 150 keV to 40 MeV for the GBM BGO detectors. Our preliminary catalog consists of galactic X-ray binaries, the Crab Nebula, and active galactic nuclei. In addition, to Earth occultations, we have observed numerous occultations with Fermi's solar panels. We will present early results. Regularly updated results can be found on our website http://gammaray.nsstc.nasa.gov/gbm/science/occultation

  20. All-Sky Earth Occultation Observations with the Fermi Gamma-Ray Burst Monitor

    Science.gov (United States)

    Wilson-Hodge, C. A.; Beklen, E.; Bhat, P. N.; Briggs, M.; Camero-Arranz, A.; Case, G.; Jenke, P.; Chaplin, V.; Cherry, M.; Connaughton, V.; Finger, M.; Haynes, R. H.; Preece, R.; Rodi, J.

    2009-01-01

    Using the Gamma Ray Burst Monitor (GBM) on-board Fermi, we are monitoring the hard X-ray/ soft gamma ray sky using the Earth occultation technique. Each time a source in our catalog is occulted by (or exits occultation by) the Earth, we measure its flux using the change in count rates due to the occultation. Currently we are using CTIME data with 8 energy channels spanning 8 keV to 1 MeV for the GBM NaI detectors and spanning 150 keV to 40 MeV for the GBM BGO detectors. Our preliminary catalog consists of galactic X-ray binaries, the Crab Nebula, and active galactic nuclei. In addition, to Earth occultations, we have observed numerous occultations with Fermi's solar panels.

  1. Occult hepatitis B in HIV-HCV coinfected patients.

    Science.gov (United States)

    Piroth, Lionel; Lafon, Marie-Edith; Binquet, Christine; Bertillon, Pascale; Gervais, Anne; Lootvoet, Enguerrand; Lang, Jean-Marie; De Jaureguiberry, Jean Pierre; Chene, Geneviève; Leport, Catherine

    2008-01-01

    The prevalence of occult hepatitis B infection in HIV infected patients is controversial, varying from less than 1% to 62% in different studies. Blood samples of 111 HIV-infected patients, HCV-positive, HBs antigen negative, followed in the APROCO-ANRS EP11 cohort, were used to detect HBV DNA by using 2 different validated assays (Cobas Amplicor HBV Monitor Test and INSERM U271 qualitative ultra-sensitive PCR), completed when positive by HBV real-time PCR. HBV DNA was found in 6 (5.4%, 95% CI 1.2%-9.6%) patients by at least 1 of these assays, but none tested positive in all 3 assays. All 6 patients had anti-HBc without anti-HBs antibodies; 5 were not on lamivudine. Their median CD4 and CD8 counts were significantly lower and their HIV viral load higher than in the other 105 patients. In conclusion, the prevalence of occult hepatitis B may vary significantly according to the molecular assay used, even though these assays are validated with high specificity and quite high sensitivity. Occult hepatitis B may be encountered in HIV-HCV coinfected patients without anti-HBV treatment, with anti-HBc but without anti-HBs antibodies, and relatively low immunity, suggesting a potential risk of further reactivation, as already sporadically reported.

  2. Renal trauma in occult ureteropelvic junction obstruction: CT findings

    Energy Technology Data Exchange (ETDEWEB)

    Sebastia, M.C.; Rodriguez-Dobao, M.; Quiroga, S.; Pallisa, E.; Martinez-Rodriguez, M.; Alvarez-Castells, A. [Dept. of Radiology, Hospital General Universitari Vall d`Hebron, Barcelona (Spain)

    1999-05-01

    The aim of this study was to present CT findings of occult ureteropelvic junction obstruction in patients with renal trauma and to describe the clinical signs and singular CT features that are characteristically observed with trauma and are relevant to management of these patients. We retrospectively reviewed 82 helical CT studies in patients with renal trauma referred to our institution. We found 13 cases of occult preexisting renal pathology, six of which were occult ureteropelvic junction obstructions. The clinical presentation, radiologic findings of trauma according to the Federle classification, and CT findings of obstructed ureteropelvic junction are presented. We found three category-I lesions (one in a horseshoe kidney), two of them treated with nephrostomy because of increased ureteropelvic junction obstruction due to pelvic clots; two category-II lesions (parenchymal and renal pelvis lacerations) that had presented only with microhematuria; and one category-IV lesion (pelvic laceration alone). Pelvic extension was demonstrated in all the cases with perirenal collections. The CT studies in all the cases with suspected ureteropelvic junction obstruction showed decreased parenchymal thickness and enhancement, and dilatation of the renal pelvis and calyx, with a normal ureter. Computed tomography can provide information to confidently diagnose underlying ureteropelvic junction obstruction in renal trauma, categorize the traumatic injury (at times clinically silent) and facilitate proper management according to the singularities observed, such us rupture of the renal pelvis alone (Federle category IV) and increasing ureteropelvic obstruction due to clots which can be decompressed by nephrostomy. (orig.) With 6 figs., 3 tabs., 13 refs.

  3. Occult pneumothoraces in patients with penetrating trauma: Does mechanism matter?

    Science.gov (United States)

    Ball, Chad G.; Dente, Christopher J.; Kirkpatrick, Andrew W.; Shah, Amit D.; Rajani, Ravi R.; Wyrzykowski, Amy D.; Vercruysse, Gary A.; Rozycki, Grace S.; Nicholas, Jeffrey M.; Salomone, Jeffrey P.; Feliciano, David V.

    2010-01-01

    Background Supine anteroposterior (AP) chest radiography is an insensitive test for detecting posttraumatic pneumothoraces (PTXs). Computed tomography (CT) often identifies occult pneumothoraces (OPTXs) not diagnosed by chest radiography. All previous literature describes the epidemiology of OPTX in patients with blunt polytrauma. Our goal was to identify the frequency of OPTXs in patients with penetrating trauma. Methods All patients with penetrating trauma admitted over a 10-year period to Grady Memorial Hospital with a PTX were identified. We reviewed patients’ thoracoabdominal CT scans and corresponding chest radiographs. Results Records for 1121 (20%) patients with a PTX (penetrating mechanism) were audited; CT imaging was available for 146 (13%) patients. Of these, 127 (87%) had undergone upright chest radiography. The remainder (19 patients) had a supine AP chest radiograph. Fifteen (79%) of the PTXs detected on supine AP chest radiographs were occult. Only 10 (8%) were occult when an upright chest radiograph was used (p thoracostomy, compared with 95% (115/121) of patients with overt PTXs (p thoracostomy use in patients with overt PTXs is significantly higher than for OPTXs in blunt and penetrating trauma. PMID:20646399

  4. Predictions of Stellar Occultations by Irregular Satellites up to 2020

    Science.gov (United States)

    Ramos Gomes, Altair; Assafin, Marcelo; Beauvalet, Laurene; Desmars, Josselin; Vieira-Martins, Roberto; Camargo, Julio I.; Morgado, Bruno Eduardo; Braga Ribas, Felipe

    2017-06-01

    Due to their orbital configurations, it is believed the irregular satellites of the Giant Planets were captured by their host planets during the Solar System evolution. It is important to know their physical parameters such as size, shape, albedo and composition in an attempt to access their origin. The best ground-based technique to do so is by stellar occultations.With the release of the GAIA catalog and the publication of a large database of positions of irregular satellites (Gomes-Júnior et al., 2015), the position of the stars and the ephemeris of the satellites are improved to better predict stellar occultation.The present work predicts such events for the 8 largest irregular satellites of Jupiter and the largest irregular satellite of Saturn, Phoebe, up to 2020. Another motivation is the passage of Jupiter in front of the Galatic Plane in 2019-2020 increasing a lot the number of stars to be occulted. The same happens with Saturn in 2018.

  5. Blob/hole formation and zonal-flow generation in the edge plasma of the JET tokamak

    DEFF Research Database (Denmark)

    Xu, G.S.; Naulin, Volker; Fundamenski, W.

    2009-01-01

    The first experimental evidence showing the connection between blob/hole formation and zonal-flow generation was obtained in the edge plasma of the JET tokamak. Holes as well as blobs are observed to be born in the edge shear layer, where zonal-flows shear off meso-scale coherent structures, lead...

  6. Occult hepatitis C virus infection: A new form of hepatitis C

    OpenAIRE

    CARREÑO, VICENTE

    2006-01-01

    Occult hepatitis C virus (HCV) infection is a new recently characterized entity. This occult infection can be present in two different clinical situations: in anti-HCV negative, serum HCV-RNA negative patients with abnormal liver function tests and in anti-HCV positive subjects with normal values of liver enzymes and without serum HCV-RNA. This review describes recent studies of occult HCV infection in both kinds of patients.

  7. Leigh Wilson, Modernism and Magic. Experiments with Spiritualism, Theosophy and the Occult

    OpenAIRE

    Marie, Florence

    2015-01-01

    In her 167-page book entitled Modernism and Magic. Experiments with Spiritualism, Theosophy and the Occult, Leigh Wilson tries to understand in what respect a certain number of modernist writers’ and avant-garde artists’ interest in theosophy, spiritualism and occult practices influenced their creations. She argues that in many cases their interest enabled them to define a new approach to mimesis without rejecting the latter altogether. She contends that magic was at the heart of the occult d...

  8. Occult hepatitis C virus infection: A new form of hepatitis C

    Institute of Scientific and Technical Information of China (English)

    Vicente Carre(n)o

    2006-01-01

    Occult hepatitis C virus (HCV) infection is a new recently characterized entity. This occult infection can be present in two different clinical situations: in anti-HCV negative,serum HCV-RNA negative patients with abnormal liver function tests and in anti-HCV positive subjects with normal values of liver enzymes and without serum HCV-RNA. This review describes recent studies of occult HCV infection in both kinds of patients.(c) 2006 The WJG Press. All rights reserved.

  9. Magnitudes of selected stellar occultation candidates for Pluto and other planets, with new predictions for Mars and Jupiter

    Science.gov (United States)

    Sybert, C. B.; Bosh, A. S.; Sauter, L. M.; Elliot, J. L.; Wasserman, L. H.

    1992-01-01

    Occultation predictions for the planets Mars and Jupiter are presented along with BVRI magnitudes of 45 occultation candidates for Mars, Jupiter, Saturn, Uranus, and Pluto. Observers can use these magnitudes to plan observations of occultation events. The optical depth of the Jovian ring can be probed by a nearly central occultation on 1992 July 8. Mars occults an unusually red star in early 1993, and the occultations for Pluto involving the brightest candidates would possibly occur in the spring of 1992 and the fall of 1993.

  10. The 1998 November 14 Occultation of GSC 0622-00345 by Saturn. I. Techniques for Ground-Based Stellar Occultations

    CERN Document Server

    Harrington, Joseph; 10.1088/0004-637X/716/1/398

    2010-01-01

    On 1998 November 14, Saturn and its rings occulted the star GSC 0622-00345. We observed atmospheric immersion with NSFCAM at the National Aeronautics and Space Administration's Infrared Telescope Facility on Mauna Kea, Hawaii. Immersion occurred at 55.5\\circ S planetocentric latitude. A 2.3 {\\mu}m, methane-band filter suppressed reflected sunlight. Atmospheric emersion and ring data were not successfully obtained. We describe our observation, light-curve production, and timing techniques, including improvements in aperture positioning, removal of telluric scintillation effects, and timing. Many of these techniques are known within the occultation community, but have not been described in the reviewed literature. We present a light curve whose signal-to-noise ratio per scale height is 267, among the best ground-based signals yet achieved, despite a disadvantage of up to 8 mag in the stellar flux compared to prior work.

  11. Light microscopical demonstration and zonal distribution of parasinusoidal cells (Ito cells) in normal human liver

    DEFF Research Database (Denmark)

    Horn, T; Junge, Jette; Nielsen, O;

    1988-01-01

    The parasinusoidal cells of the liver (Ito cells) were demonstrated light microscopically in autopsy specimens fixed in formalin and stained with Oil red O after dichromate treatment. The method allows examination of large samples containing numerous acini. Quantitative assessment showed a zonal...

  12. Zonal winds in the equatorial upper thermosphere: Decomposing the solar flux, geomagnetic activity, and seasonal dependencies

    NARCIS (Netherlands)

    Liu, H.; Lühr, H.; Watanabe, S.; Köhler, W.; Henize, V.; Visser, P.N.A.M.

    2006-01-01

    Using 3 years (2002–2004), over 16,400 orbits of measurements from the accelerometer on board the CHAMP satellite, we have studied the climatology of the equatorial zonal wind in the upper thermosphere. Several main features are noticed. The most prominent one is that the solar flux significantly in

  13. Dynamics of zonal flow saturation in strong collisionless drift wave turbulence

    Science.gov (United States)

    Kim, Eun-jin; Diamond, P. H.

    2002-11-01

    Generalized Kelvin-Helmholtz (GKH) instability is examined as a mechanism for the saturation of zonal flows in the collisionless regime. By focusing on strong turbulence regimes, GKH instability is analyzed in the presence of a background of finite-amplitude drift waves. A detailed study of a simple model with cold ions shows that nonlinear excitation of GKH modes via modulational instability can be comparable to their linear generation. Furthermore, it is demonstrated that zonal flows are likely to grow faster than GKH mode near marginality, with insignificant turbulent viscous damping by linear GKH. The effect of finite ion temperature fluctuations is incorporated in a simple toroidal ion temperature gradient model, within which both zonal flow and temperature are generated by modulational instability. The phase between the two is calculated self-consistently and shown to be positive. Furthermore, the correction to nonlinear generation of GKH modes appears to be small, being of order O(ρi2k2). Thus, the role of linear GKH instability in the saturation of collisionless zonal flows, in general, seems dubious.

  14. The Effect of Zonally Asymmetric Ozone Heating on the Northern Hemisphere Winter Polar Stratosphere

    Science.gov (United States)

    2010-12-09

    winds). Differences in the ensemble mean winds are negligible throughout much of December. In Jan - uary, the 3DO3 mean westerly winds are ∼5 m s−1...wave propagation versus wave damping in modulating the planetary wave drag and thus the zonal-mean circulation. Acknowledgments. We thank John Albers

  15. The role of plasma elongation on the linear damping of zonal flows

    Science.gov (United States)

    Angelino, P.; Garbet, X.; Villard, L.; Bottino, A.; Jolliet, S.; Ghendrih, Ph.; Grandgirard, V.; McMillan, B. F.; Sarazin, Y.; Dif-Pradalier, G.; Tran, T. M.

    2008-06-01

    Drift wave turbulence is known to self-organize to form axisymmetric macroscopic flows. The basic mechanism for macroscopic flow generation is called inverse energy cascade. Essentially, it is an energy transfer from the short wavelengths to the long wavelengths in the turbulent spectrum due to nonlinear interactions. A class of macroscopic flows, the poloidally symmetric zonal flows, is widely recognized as a key constituent in nearly all cases and regimes of microturbulence, also because of the realization that zonal flows are a critical agent of self-regulation for turbulent transport. In tokamaks and other toroidal magnetic confinement systems, axisymmetric flows exist in two branches, a zero frequency branch and a finite frequency branch, named Geodesic Acoustic Modes (GAMs). The finite frequency is due to the geodesic curvature of the magnetic field. There is a growing body of evidence that suggests strong GAM activity in most devices. Theoretical investigation of the GAMs is still an open field of research. Part of the difficulty of modelling the GAMs stems from the requirement of running global codes. Another issue is that one cannot determine a simple one to one relation between turbulence stabilization and GAM activity. This paper focuses on the study of ion temperature gradient turbulence in realistic tokamak magnetohydrodynamic equilibria. Analytical and numerical analyses are applied to the study of geometrical effects on zonal flows oscillations. Results are shown on the effects of the plasma elongation on the GAM amplitude and frequency and on the zonal flow residual amplitude.

  16. The páramo vegetation of Ramal de Guaramacal, Trujillo State, Venezuela. 1. Zonal communities

    NARCIS (Netherlands)

    Cuello A., N.L.; Cleef, A.M.

    2009-01-01

    Zonal páramo vegetation communities present on top of Ramal de Guaramacal, Trujillo state, Venezuela, have been studied with the aim to provide a syntaxonomic scheme or classification, based on analysis of the physiognomy, floristic composition, ecological relations and spatial distribution of the

  17. The paramo vegetation of Ramal de Guaramacal, Trujillo State, Venezuela. 1. Zonal communities

    NARCIS (Netherlands)

    Cuello, A.N.L.; Cleef, A.M.

    2009-01-01

    Zonal paramo vegetation communities present on top of Ramal de Guaramacal, Trujillo state, Venezuela, have been studied with the aim to provide a syntaxonomic scheme or classification, based oil analysis of the physiognomy, floristic composition, ecological relations and spatial distribution of the

  18. Daytime zonal drifts in the ionospheric E and 150 km regions estimated using EAR observations

    Science.gov (United States)

    Peddapati, PavanChaitanya; Otsuka, Yuichi; Yamamoto, Mamoru; Yokoyama, Tatsuhiro; Patra, Amit

    2016-07-01

    The Equatorial Atmosphere Radar (EAR), located at Kototabang (0.2o S, 100.32o E, mag. lat. 10.36o S), Indonesia, is capable of detecting both E region and 150 km echoes during daytime. We have conducted multi-beam observations using the EAR during daytime covering all seasons to study seasonal variations of these echoes and their dynamics. Given the facts that drifts at the 150 km region are governed primarily by electric field, drifts at the E region are governed by both electric field and neutral wind, simultaneous observations of drifts in both E and 150 km regions would help understand their variations. In this paper we present local time and seasonal variations of zonal drifts in the E and 150 km regions estimated using multi-beam observations. Zonal drifts (positive eastward) in the E and 150 km regions are found to be in the range of -10 to -60 m/s and -40 to 80 m/s, respectively. In the E region, zonal drifts show height reversal and temporal variations having tidal signature and noticeable seasonal variations. Zonal drifts in the 150 km region also show noticeable height and seasonal variations. These results are compared with model drifts and evaluated in terms of electric field and neutral wind.

  19. Climate Prediction Center (CPC) Area-average 200-hPa Zonal Wind Anomalies

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is one of the CPC?s Monthly Atmospheric and SST Indices. It is the 200-hPa zonal wind anomalies averaged over the area 5oN ? 5oS, 165oW-110oW. The anomalies are...

  20. Self-Organization of Zonal Jets in Outer Planet Atmospheres: Uranus and Neptune

    Science.gov (United States)

    Friedson, A. James

    1997-01-01

    The statistical mechnical theory of a two-dimensional Euler fluid is appleid for the first time to explore the spontaneous self-oganization of zonal jets in outer planet atmospheres. Globally conserved integralls of motion are found to play a central role in defining jet structure.

  1. Effects of gaseous hydrogen fluoride on oxidative enzymes of Pelargonium zonale leaves

    Energy Technology Data Exchange (ETDEWEB)

    Poovaiah, B.W.; Wiebe, H.H.

    1971-10-01

    Changes in peroxidase and cytochrome oxidase enzymes were established histochemically in hydrogen fluoride fumigated leaves of Pelargonium zonale. Highest peroxidase and cytochrome oxidase activities were localized near the injured areas of fumigated leaves, and the greatest increase was observed in the phloem region.

  2. Analysis of antifungal and anticancer effects of the extract from Pelargonium zonale.

    Science.gov (United States)

    Lewtak, Kinga; Fiołka, Marta J; Szczuka, Ewa; Ptaszyńska, Aneta A; Kotowicz, Natalia; Kołodziej, Przemysław; Rzymowska, Jolanta

    2014-11-01

    The extract from Pelargonium zonale stalks exhibits activity against Candida albicans and exerts an effect on the HeLa cell line. The action against C. albicans cells was analysed using light, CLSM, SEM, and TEM microscopes. The observations indicate that the extract influenced fungal cell morphology and cell metabolic activity. The morphological changes include cell wall damage, deformations of cell surfaces, and abnormalities in fungal cell shape and size. Cells of C. albicans treated with the extract exhibited disturbances in the budding pattern and a tendency to form agglomerates and multicellular chains. The P. zonale extract caused a significant decrease in the metabolic activity of C. albicans cells. Cells died via both apoptosis and necrosis. The antitumor activity of the extract was analysed using the MTT assay. The P. zonale extract exhibited minor cytotoxicity against the HeLa cell line but a dose-dependent cytopathic effect was noticed. The P. zonale extract is a promising source for the isolation of antifungal and anticancer compounds.

  3. A Rare Excitatory Amino Acid from Flowers of Zonal Geranium responsible for Paralyzing the Japanese Beetle

    Science.gov (United States)

    e Japanese beetle (Popillia japonica) exhibits rapid paralysis after consuming flowers from zonal geranium (Pelargonium × hortorum). Activity-guided fractionations were conducted with polar flower petal extracts from Pelargonium × hortorum cv. Nittany Lion Red, which led to the isolation of a paraly...

  4. Light microscopical demonstration and zonal distribution of parasinusoidal cells (Ito cells) in normal human liver

    DEFF Research Database (Denmark)

    Horn, T; Junge, Jette; Nielsen, O

    1988-01-01

    The parasinusoidal cells of the liver (Ito cells) were demonstrated light microscopically in autopsy specimens fixed in formalin and stained with Oil red O after dichromate treatment. The method allows examination of large samples containing numerous acini. Quantitative assessment showed a zonal ...

  5. Evaluation of Sub-Zonal Airflow Models for the Prediction of Local Interior Boundary Conditions

    DEFF Research Database (Denmark)

    Steskens, Paul W. M. H.; Janssen, Hans; Rode, Carsten

    2013-01-01

    and applicability of the sub-zonal airflow model to predict the local indoor environmental conditions, as well as the local surface transfer coefficients near building components. Two test cases were analyzed for, respectively, natural and forced convection in a room. The simulation results predicted from the sub...

  6. High prevalence of occult hepatitis C virus infection in patients with chronic hepatitis B virus infection.

    Science.gov (United States)

    Castillo, Inmaculada; Bartolomé, Javier; Quiroga, Juan Antonio; Carreño, Vicente

    2013-08-01

    Hepatitis C virus (HCV) infection in the absence of detectable antibodies against HCV and of viral RNA in serum is called occult HCV infection. Its prevalence and clinical significance in chronic hepatitis B virus (HBV) infection is unknown. HCV RNA was tested for in the liver samples of 52 patients with chronic HBV infection and 21 (40 %) of them were positive for viral RNA (occult HCV infection). Liver fibrosis was found more frequently and the fibrosis score was significantly higher in patients with occult HCV than in negative ones, suggesting that occult HCV infection may have an impact on the clinical course of HBV infection.

  7. High spatial resolution multi-color observations of Neptune during occultation by the moon

    Science.gov (United States)

    Veverka, J.

    1976-01-01

    Preparations for the observation of Mars occultation using the 36 inch telescope on a C-141 airborne observatory were described, including technical improvements made to existing equipment. The abstracts of the following four publications supported by the grant were presented: (1) atmosphere composition from refractivity measurements made during occultations, (2) how big is lapetus?, (3) the diameter of Titan, (4) design and operating characteristics of voltage to frequency converters suited for occultation work. The planned observation of the April 8, 1976 occultation of the epsilon Gem star from the C-141 airborne observatory was described.

  8. Effects of density stratification in driving zonal flow in gas giants

    Science.gov (United States)

    Gastine, T.; Wicht, J.

    2011-12-01

    The banded structures at the surfaces of Jupiter and Saturn are associated with prograde and retrograde zonal flows. The depth of these jets remains however poorly known. Theoretical scenarios range from ``shallow models'', that assume that zonal flows are restricted to a very thin layer close to the surface; to ``deep models'' that suppose that the jets involve the whole molecular shell (typically 104 kms). The latter idea was supported by fully 3-D numerical simulations (e.g. Heimpel, 2005) using the Boussinesq approximation, meaning that the background properties (temperature, density, ...) are constant with radius (Christensen, 2002). While this approximation is suitable for liquid iron cores of planets, it is more questionable in the envelopes of gas giants, where density increases by several orders of magnitude (Guillot, 1999). The anelastic approximation provides a more realistic framework to simulate the dynamics of zonal flows as it allows compressibility effects, while filtering out fast acoustic waves (Lantz & Fan, 1999). Recent anelastic simulations suggest that including compressibility effects yields interesting differences to Boussinesq approaches (Jones, 2009; Showman et al., 2011). Here, we therefore adopt an anelastic formulation to simulate 3-D compressible flows in rapidly rotating shells. We have conducted a systematic parametric study on the effects of background density stratification and analysed the influences on both convective flows and zonal jets. Despite the strong dependence of convection on the density stratification (i.e. the typical lengthscale of convective flows decreases when compressibility increases), the comparison between Boussinesq and anelastic simulations reveals striking common features: the latitudinal extent, the amplitude and the number of zonal jets is found to be nearly independent of the density stratification, provided convection is strongly driven. Mass-weighted properties of the flow (and notably a mass

  9. GPS occultation data products from the GRAS SAF

    Science.gov (United States)

    Larsen, G. B.; Lauritsen, K. B.; Rubek, F.; Soerensen, M. B.

    2003-04-01

    The EUMETSAT network of Satellite Application Facilities (SAFs) will, together with the EUMETSAT central facilities, constitute the future EUMETSAT Application Ground Segments (AGS) for the MSG and EPS/Metop satellites. The developments of the Global Navigation Satellite System (GNSS) Receiver for Atmospheric Sounding (GRAS) Meteorology SAF (hereafter the GRAS SAF) started in 1999 with participation from the Danish Meteorological Institute (DMI), IEEC (Spain), and Met Office (UK). The host institute is the DMI and this will also be the physical location of the operational GRAS SAF data facility. The GRAS SAF will receive raw and preprocessed GPS radio occultation data from the GRAS instrument onboard the Metop satellite, process these into vertical height profiles of refractivity, temperature, pressure, and humidity, and distribute these products continuously in near real time to numerical weather prediction and climate monitoring users. A second objective of the GRAS SAF is to supply software for 4DVAR-assimilation of radio occultation data into numerical weather prediction models. The GRAS SAF will enter into the operational phase and deliver products in the last half of 2006 given the current launch plans for Metop. The basic principle in the GRAS SAF project is the radio occultation method where a receiver onboard a low-orbiting satellite tracks GNSS signals as the transmitting satellite sets or rises behind the Earth (occultation). Due to refraction in the ionosphere and the neutral atmosphere the signal is delayed and its path bent, enabling calculation of the refractivity and subsequently temperature, pressure and humidity as a function of height. The main users of the GRAS SAF products will be meteorologists doing data assimilation (Near-Real Time Products, delivered less than three hours after measurement) and users from the climate research and atmospheric science communities (improved Offline Products, delivered less than 30 days after measurement

  10. Climate Change Detection in the UTLS with the GPS Radio Occultation Record

    Science.gov (United States)

    Steiner, A. K.; Kirchengast, G.; Lackner, B. C.; Hegerl, G. C.; Pirscher, B.; Foelsche, U.

    2009-12-01

    Radio Occultation (RO) based on signals from Global Positioning System (GPS) satellites provides a new climate record of high quality and vertical resolution in the upper troposphere and lower stratosphere (UTLS). RO data are considered a climate benchmark data type since they are based on timing with precise atomic clocks and tied to the international definition of the second. Long-term stability and the consistency of RO data stemming from different satellites (without need for inter-calibration) make RO well suited for climate change detection. RO data are available on a continuous basis from Sep 2001 to Sep 2008 from the CHAMP satellite and intermittent periods of observations from the GPS/Met proof-of-concept mission exist in the years 1995-1997, with sufficient data only for Oct 1995 and Feb 1997. We present a climate change detection study based on monthly mean zonal mean RO climatologies in the UTLS region within 9-25 km (300-30 hPa) where we use different detection methods. An optimal fingerprinting technique is applied to the whole record of RO accessible parameters refractivity, geopotential height, and temperature to detect a forced climate signal. Three representative global climate models of the 4th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) are employed to estimate natural climate variability using pre-industrial control runs. The response pattern to the external forcings is presented by an ensemble mean of the models' A2 and B1 scenario runs. Optimal fingerprinting shows that a climate change signal can be detected in the RO refractivity and in the RO temperature record (90 % significance level). Furthermore, standard and multiple linear regression is applied to temperature time series for February (1997 and 2002-2008) and for October (1995 and 2001-2007), taking RO errors into account. In the tropics, we also investigate the influence of stratospheric quasi-biennial oscillation (QBO) and tropospheric El Nino

  11. Quantifying uncertainty in climatological fields from GPS radio occultation: an empirical-analytical error model

    Directory of Open Access Journals (Sweden)

    B. Scherllin-Pirscher

    2011-05-01

    Full Text Available Due to the measurement principle of the radio occultation (RO technique, RO data are highly suitable for climate studies. Single RO profiles can be used to build climatological fields of different atmospheric parameters like bending angle, refractivity, density, pressure, geopotential height, and temperature. RO climatologies are affected by random (statistical errors, sampling errors, and systematic errors, yielding a total climatological error. Based on empirical error estimates, we provide a simple analytical error model for these error components, which accounts for vertical, latitudinal, and seasonal variations. The vertical structure of each error component is modeled constant around the tropopause region. Above this region the error increases exponentially, below the increase follows an inverse height power-law. The statistical error strongly depends on the number of measurements. It is found to be the smallest error component for monthly mean 10° zonal mean climatologies with more than 600 measurements per bin. Due to smallest atmospheric variability, the sampling error is found to be smallest at low latitudes equatorwards of 40°. Beyond 40°, this error increases roughly linearly, with a stronger increase in hemispheric winter than in hemispheric summer. The sampling error model accounts for this hemispheric asymmetry. However, we recommend to subtract the sampling error when using RO climatologies for climate research since the residual sampling error remaining after such subtraction is estimated to be 50 % of the sampling error for bending angle and 30 % or less for the other atmospheric parameters. The systematic error accounts for potential residual biases in the measurements as well as in the retrieval process and generally dominates the total climatological error. Overall the total error in monthly means is estimated to be smaller than 0.07 % in refractivity and 0.15 K in temperature at low to mid latitudes, increasing towards

  12. Profiling the atmosphere with the airborne radio occultation technique

    Science.gov (United States)

    Muradyan, Paytsar

    The GNSS Instrument System for Multistatic and Occultation Sensing (GISMOS) was designed for dense sampling of meteorological targets using the airborne radio occultation (RO) technique. Airborne RO refers to an atmospheric limb sounding technique in which Global Positioning System (GPS) signals are recorded at a receiver onboard an aircraft as the satellites descend beyond the limb of the Earth. The GPS signals, that are unaffected by clouds and precipitation, experience refractive bending as well as a delay in the travel time through the atmosphere. Bending can be used to retrieve information about atmospheric refractivity, which depends on atmospheric moisture and temperature. The new system has the potential for improving numerical weather prediction (NWP) forecasts through assimilation of many high-resolution atmospheric profiles in an area of interest, compared to spaceborne RO, which samples sparsely around the globe. In February 2008, GISMOS was deployed on the National Science Foundation Gulfstream-V aircraft to make atmospheric observations in the Gulf of Mexico coastal region with an objective to test the performance of the profiling system. Recordings from this flight campaign made with the conventional phase lock loop GPS receivers descend from flight level to 5 km altitude. However, below that level strong refractivity gradients, especially those associated with the boundary layer, cause rapid phase accelerations resulting in loss of lock in the receiver. To extend the RO profiles deeper in the atmosphere, the GISMOS system was also equipped with a GPS Recording System (GRS) that records the raw RF signals. Post-processing this dataset in open-loop (OL) tracking mode enables reliable atmospheric profiling at lower altitudes. We present a comprehensive analysis of the performance of the airborne system OL tracking algorithm during a 5 hour flight on 15 February 2008. Excess phase and amplitude profiles for 5 setting and 5 rising occultations were

  13. 3D Effects in the Formation of Zonal Jets Through Inverse Cascade

    Science.gov (United States)

    Sayanagi, K. M.; Showman, A. P.

    2006-12-01

    The atmospheric zonal jets on Jupiter and Saturn are characterized by the broad, prograde, equatorial jet and the narrower, higher-latitude jets that alternate between prograde and retrograde. The question of what controls the widths and directions of those jets remains a major unsolved problem in geophysical fluid dynamics. Past studies have shown that, in shallow flows on a rotating sphere, small random vortices can undergo inverse cascade to form zonal jets with a characteristic width called the Rhines scale. Most of the studies to date use 2D non-divergent or shallow-water models in studying this zonal jet formation mechanism. However, in the parameter ranges representative of the Jovian conditions, the flows produced by 2D non- divergent models are typically dominated by strong circumpolar jets, and the shallow-water models produce a robust retrograde equatorial jet. These models' apparent inabilities in reproducing some key Jovian jet features may suggest the importance of 3D effects in controlling the jets' large-scale horizontal structures. To date, Kitamura and Matsuda (Fluid Dynamics Research, 34, 33-57, 2004) is the only published study that analyzes the 3D effects in the zonalization of fine-scale random turbulence through the inverse cascade. Their two-layer primitive equation simulations of free-evolving flows resulted in circumpolar jet dominated flows, although slower mid-latitude jets are also present. Our study is a significant extension over that by Kitamura and Matsuda and includes substantially more layers to study the zonalization process to more fully resolve relevant 3D effects in the inverse cascade. We test the flow behavior's dependence on the deformation radius and the resulting vertical structures in both spherical and beta-plane geometries. Our study uses the Explicit Planetary Isentropic Coordinate (EPIC) model (Dowling et al, Icarus, 32, 221-238., 1998). The research is supported by a NASA Planetary Atmospheres grant to APS.

  14. Zonal jets and QBO-like oscillations on Jupiter and Saturn

    Science.gov (United States)

    Showman, Adam P.; Zhang, Xi; Tan, Xianyu

    2016-10-01

    At the levels of their visible cloud decks, the giant planets Jupiter and Saturn exhibit numerous east-west (zonal) jet streams with speeds ranging up to 150 m/sec on Jupiter and 400 m/sec on Saturn. Moreover, both planets exhibit long-term stratospheric oscillations involving perturbations of zonal wind and temperature that propagate downward over time on timescales of ~4 years (Jupiter) and ~15 years (Saturn). These oscillations, dubbed the Quasi Quadrennial Oscillation (QQO) for Jupiter and the Semi-Annual Oscillation (SAO) on Saturn, are thought to be analogous to the Quasi-Biennial Oscillation (QBO) on Earth, which is driven by upward propagation of equatorial waves from the troposphere. Here, we test the hypothesis that the zonal jets on Jupiter and Saturn, as well as QBO-like oscillations, can result from interaction of the stably stratified atmosphere with an underlying convective interior. We performed global, three-dimensional, high-resolution numerical simulations of the flow in the stratosphere and upper troposphere of Jupiter-like planets. The effect of convection is parameterized by introducing thermal perturbations that randomly perturb the radiative convective boundary with some characteristic timescale, horizontal wavenumber, and amplitude. Radiative damping is represented using a Newtonian cooling scheme with a characteristic radiative time constant. In the simulations, the convective perturbations generate atmospheric waves and turbulence that interact with the rotation to produce numerous zonal jets. Moreover, the equatorial stratosphere exhibits stacked eastward and westward jets that migrate downward over time, exactly as occurs in the terrestrial QBO, Jovian QQO, and Saturnian SAO. This is the first demonstration of a QBO-like phenomenon in 3D numerical simulations of a giant planet. We will describe how the properties of the zonal jets and equatorial oscillation depend on the details of the forcing and damping. These simulations have

  15. Spontaneous generation of self-organized zonal flows in turbulent plasma

    Science.gov (United States)

    Trines, Raoul

    2008-11-01

    Drift wave turbulence is ubiquitous in magnetised plasma, in particular on density gradients that can be found in plasma edge configurations. Such configurations arise in both laboratory and space environments, while appropriate scaling the equations governing the drift waves allows them to be applied over a wide range of length and time scales. Therefore, the study of drift wave dynamics has applications ranging from the magnetosphere boundary to small laboratory plasma devices such as CSDX at UCSD [G.R. Tynan et al., J. Vac. Sci. Tech-A 15, 2885 (1997)]. Recently, it was found that the interaction between drift modes and zonal flows at a plasma edge leads to self-organisation of the drift waves and the formation of solitary zonal flow structures [R. Trines et al., Phys. Rev. Lett. 94, 165002 (2005)]. The interaction between broadband drift mode turbulence and zonal flows has been studied in numerical simulations based on the wave-kinetic approach. In these simulations, a particle-in-cell representation is used for the quasi-particles, while a fluid model is employed for the plasma. Simulation results show the development of self-organised zonal flow through the modulational instability of the drift wave distribution, as well as the existence of solitary zonal flow structures about an ion gyro-radius wide, drifting towards steeper relative density gradients. These results will be compared to observations made at the magnetopause by the Cluster satellites [R. Trines et al., Phys. Rev. Lett. 99, 205006 (2007)] and to measurements performed on CSDX. This work is supported by the STFC Accelerator Science and Technology Centre and the STFC Centre for Fundamental Physics.

  16. Low-frequency intraseasonal variability in a zonally symmetric aquaplanet model

    Science.gov (United States)

    Das, Surajit; Sengupta, Debasis; Chakraborty, A.; Sukhatme, Jai; Murtugudde, Raghu

    2016-12-01

    We use the aquaplanet version of the community atmospheric model, with perpetual spring equinox forcing and zonally symmetric sea surface temperature (SST), to study tropical intraseasonal oscillations (ISOs). In the first two experiments, we specify zonally symmetric SST profiles that mimic observed climatological July and January SSTs as surface boundary conditions. In the January SST simulation, we find a zonal wavenumber 1 mode with dominant period of 60 days, moving east at about 6 m s-1. This mode, which resembles the Madden-Julian oscillation (MJO), is absent in the July SST case, although convectively coupled Kelvin waves are prominent in both experiments. To further investigate the influence of tropical SST on ISO and convectively coupled equatorial waves, we conduct experiments with idealised symmetric SST profiles having different widths of warm ocean centered at the equator. In the narrowest SST experiment, the variance of moist activity is predominantly in weather-scale Kelvin waves. When the latitudinal extent of warm SST is comparable to or larger than the equatorial Rossby radius, we find a dominant low frequency (50-80 days) eastward mode that resembles the MJO, as in the January SST experiment. We also find westward propagating waves with intraseasonal (30-120 days) periods and zonal wavenumber 1-3; the structure of these signals projects onto equatorially trapped Rossby waves with meridional mode numbers 1, 3 and 5, associated with convection that is symmetric about the equator. In addition, the model generates 30-80 days westward moving signals with zonal wavenumber 4-7, particularly in the narrow SST experiment. Although these waves are seen in the wavenumber-frequency spectra in the equatorial region, they have largest amplitude in the middle and high latitudes. Thus, our study shows that wider, meridionally symmetric SST profiles support a strong MJO-like eastward propagation, and even in an aquaplanet setting, westward propagating Rossby

  17. Mutations associated with occult hepatitis B in HIV-positive South Africans.

    Science.gov (United States)

    Powell, Eleanor A; Gededzha, Maemu P; Rentz, Michael; Rakgole, Nare J; Selabe, Selokela G; Seleise, Tebogo A; Mphahlele, M Jeffrey; Blackard, Jason T

    2015-03-01

    Occult hepatitis B is characterized by the absence of hepatitis B surface antigen (HBsAg) but the presence of HBV DNA. Because diagnosis of hepatitis B virus (HBV) typically includes HBsAg detection, occult HBV remains largely undiagnosed. Occult HBV is associated with increased risk of hepatocellular carcinoma, reactivation to chronic HBV during immune suppression, and transmission during blood transfusion and liver transplant. The mechanisms leading to occult HBV infection are unclear, although viral mutations are likely a significant factor. In this study, sera from 394 HIV-positive South Africans were tested for HBV DNA and HBsAg. For patients with detectable HBV DNA, the overlapping surface and polymerase open reading frames (ORFs) were sequenced. Occult-associated mutations-those mutations found exclusively in individuals with occult HBV infection but not in individuals with chronic HBV infection from the same cohort or GenBank references-were identified. Ninety patients (22.8%) had detectable HBV DNA. Of these, 37 had detectable HBsAg, while 53 lacked detectable surface antigen. The surface and polymerase ORFs were cloned successfully for 19 patients with chronic HBV and 30 patients with occult HBV. In total, 235 occult-associated mutations were identified. Ten occult-associated mutations were identified in more than one patient. Additionally, 15 amino acid positions had two distinct occult-associated mutations at the same residue. Occult-associated mutations were common and present in all regions of the surface and polymerase ORFs. Further study is underway to determine the effects of these mutations on viral replication and surface antigen expression in vitro.

  18. Anisotropic turbulence and zonal jets in rotating flows with a β-effect

    Directory of Open Access Journals (Sweden)

    B. Galperin

    2006-01-01

    Full Text Available Numerical studies of small-scale forced, two-dimensional turbulent flows on the surface of a rotating sphere have revealed strong large-scale anisotropization that culminates in the emergence of quasi-steady sets of alternating zonal jets, or zonation. The kinetic energy spectrum of such flows also becomes strongly anisotropic. For the zonal modes, a steep spectral distribution, E(n=CZ (Ω/R2 n-5, is established, where CZ=O(1 is a non-dimensional coefficient, Ω is the angular velocity, and R is the radius of the sphere, respectively. For other, non-zonal modes, the classical, Kolmogorov-Batchelor-Kraichnan, spectral law is preserved. This flow regime, referred to as a zonostrophic regime, appears to have wide applicability to large-scale planetary and terrestrial circulations as long as those are characterized by strong rotation, vertically stable stratification and small Burger numbers. The well-known manifestations of this regime are the banded disks of the outer planets of our Solar System. Relatively less known examples are systems of narrow, subsurface, alternating zonal jets throughout all major oceans discovered in state-of-the-art, eddy-permitting simulations of the general oceanic circulation. Furthermore, laboratory experiments recently conducted using the Coriolis turntable have basically confirmed that the lateral gradient of ''planetary vorticity'' (emulated via the topographic β-effect is the primary cause of the zonation and that the latter is entwined with the development of the strongly anisotropic kinetic energy spectrum that tends to attain the same zonal and non-zonal distributions, −5 and , respectively, in both the slope and the magnitude, as the corresponding spectra in other environmental conditions. The non-dimensional coefficient CZ in the −5 spectral law appears to be invariant, , in a variety of simulated and natural flows. This paper provides a brief review of the zonostrophic regime. The review includes the

  19. A simplified approach for generating GNSS radio occultation refractivity climatologies

    Directory of Open Access Journals (Sweden)

    H. Gleisner

    2012-07-01

    Full Text Available The possibility of simplifying the retrieval scheme required to produce GNSS radio occultation refractivity climatologies is investigated. In a new, simplified retrieval approach, the main statistical analysis is performed in bending angle space and an estimate of the average bending angle profile is then propagated through an Abel transform. The average is composed of means and medians of ionospheric corrected bending angles up to 80 km. Above that, the observed profile is exponentially extrapolated to infinity using a fixed a priori scale height. The new approach circumvents the need to introduce a "statistical optimization" processing step in which individual bending-angle profiles are merged with a priori data, often taken from a climatology. This processing step can be complex, difficult to interpret, and is generally recognized as a potential source of structural uncertainty. The new scheme is compared with the more conventional approach of averaging individual refractivity profiles, produced with the implementation of statistical optimization used in the EUMETSAT Radio Occultation Meteorology Satellite Application Facility (ROM SAF operational processing. It is shown that the two GNSS radio occultation climatologies agree to within 0.1% from 5 km up to 35–40 km, for the three months January, February, and March 2011. During this time period, the new approach also produces slightly better agreement with ECMWF analyses between 40–50 km, which is encouraging. The possible limitations of the new approach caused by mean residual ionospheric errors and low observation numbers are discussed briefly, and areas for future work are suggested.

  20. Comparative study between occult hepatitis C virus infection and chronic hepatitis C.

    Science.gov (United States)

    Pardo, M; López-Alcorocho, J M; Rodríguez-Iñigo, E; Castillo, I; Carreño, V

    2007-01-01

    We have recently described the presence of occult hepatitis C virus (HCV) infection (HCV-RNA in liver in the absence of anti-HCV and serum HCV-RNA) in patients with persistently abnormal liver function tests of unknown aetiology. The aim of this study was to compare the characteristics of patients with occult HCV infection vs those of patients with chronic hepatitis C. We compared clinical features of 68 patients with occult HCV infection and 69 untreated chronic HCV patients (anti-HCV and serum HCV-RNA positive), matched for age, gender, duration of abnormal liver function tests and body mass index. Aspartate aminotransferase and alanine aminotransferase were higher (P < 0.001) in chronic HCV, but cholesterol and triglycerides were significantly higher in patients with occult HCV infection (P < 0.001 and P = 0.002). Chronic HCV patients had higher gamma-globulin (P = 0.005), alpha-foetoprotein (P < 0.001) and iron (P < 0.001) levels. Percentage of patients with necroinflammatory activity and fibrosis was higher (P < 0.001) in chronic HCV than in occult HCV infection. Mean percentage of infected hepatocytes was higher (P = 0.001) in chronic HCV (10.1%) than in occult HCV infection (5.3%). This occult HCV infection is a milder disease than chronic HCV, and this could be related to the significantly lower number of infected hepatocytes observed in occult HCV.

  1. Hepatitis C virus infection in the family setting of patients with occult hepatitis C.

    Science.gov (United States)

    Castillo, Inmaculada; Bartolomé, Javier; Quiroga, Juan Antonio; Barril, Guillermina; Carreño, Vicente

    2009-07-01

    Family members of patients with chronic hepatitis C virus (HCV) infection are at increased risk of HCV infection but the prevalence of HCV among family members of patients with occult HCV infection is not known. Anti-HCV, serum HCV RNA and levels of liver enzymes were determined in 102 family members of 50 index patients with occult HCV infection and in 118 family members of 59 chronic hepatitis C index patients. HCV RNA and/or anti-HCV were detected in 10/102 (9.8%) relatives of patients with occult HCV infection and in 4/118 (3.4%) of patients with chronic hepatitis C. Fourteen additional family members (seven were relatives of index patients with occult HCV infection) had abnormal values of liver enzymes without serological markers of HCV infection. Two of these patients (who were relatives of two index patients with occult HCV infection) underwent a liver biopsy and were diagnosed with an occult HCV infection because HCV RNA was detected in the liver cells in the absence of serological HCV markers. In conclusion, the prevalence of HCV infection among family members of patients with occult HCV infection was similar to that found among family members of patients with chronic hepatitis C. This stresses the need to adopt strategies to prevent the transmission of HCV in the family setting of patients with occult HCV infection.

  2. The Lunar Occultation Observer (LOCO) - A Nuclear Astrophysics All-Sky Survey Mission Concept

    Science.gov (United States)

    Miller, R. S.; Bonamente, M.; Burgess, J. M.; Harmon, B. A.; Jenke, P.; Lawrence, D. J.; O'Brien, S.; Orr, M. R.; Paciesas, W. S.; Young, C. A.

    2008-07-01

    The Lunar Occultation Observer (LOCO) is a new lunar-based concept to probe the nuclear astrophysics regime. It will be a pioneering mission in high-energy astrophysics: the first to employ occultation as the principle detection and imaging method.

  3. A New Double Star Observed During Lunar Occultation: TYC 6312-00761-1

    Science.gov (United States)

    Gault, Dave; Herald, Dave

    2016-10-01

    A lunar occultation observation by DG in March 2013 detected a new, previously unknown companion of star TYC 6312-00761-1. Subsequent lunar occultation observation by DH in September 2015 confirms the double star nature and the two observations when combined gives the solution; Sep = 0.527", PA = 131.59 degrees, at a Mean Date of 2014.45.

  4. Science, occultism, and the art of the avant-garde in the early twentieth century

    NARCIS (Netherlands)

    Bauduin, T.M.

    2012-01-01

    In the early twentieth century, scientific discoveries such as n-dimensionality, x-rays, and electromagnetism made their way into the discourse of Occultism, where they were subsequently reframed as the occult fourth dimension, clairvoyant x-ray vision, and thought vibration. As this article will sh

  5. Presentation of occult Chiari I malformation following spinal anesthesia

    Directory of Open Access Journals (Sweden)

    Saravanan P Ankichetty

    2012-01-01

    Full Text Available Chiari I malformation (CM-I manifests with tonsillar herniation below foramen magnum. These patients are at high risk of respiratory depression and bulbar dysfunction in the perioperative period with underlying obstructive sleep apnea. However, the safe use of both general and regional anaesthesia has been documented in a known CM-I parturients. We describe the successful management of a patient who had hypercapnic respiratory failure in the post-anaesthetic care unit following an uneventful subarachnoid block for left knee replacement surgery. This patient was retrospectively diagnosed with occult CM-I and moderate to severe obstructive sleep apnea in the postoperative period.

  6. Visualization and data sharing of COSMIC radio occultation dataset

    Science.gov (United States)

    Ho, Y.; Weber, W. J.; Chastang, J.; Murray, D.; McWhirter, J.; Integrated Data Viewer

    2010-12-01

    Visualizing the trajectory and the sounding profile of the COSMIC netCDF dataset, and its evolution through time is developed in Unidata's Integrated data Viewer (IDV). The COSMIC radio occultation data is located in a remote data server called RAMADDA, which is a content management system for earth science data. The combination of these two software packages provides a powerful visualization and analysis tools for sharing real time and archived data for research and education. In this presentation we would like to demonstrate the development and the usage of these two software packages.

  7. Radio Occultation Bending Angle Anomalies During Tropical Cyclones

    DEFF Research Database (Denmark)

    Biondi, Riccardo; Neubert, Torsten; Syndergaard, Stig

    The tropical deep convection affects the radiation balance of the atmosphere changing the water vapor mixing ratio and the temperature of the upper troposphere lower stratosphere. The aim of this work is to better understand these processes and to investigate if severe storms leave a significant ...... on the International Space Station....... than the annual mean of the atmosphere around the tropopause. Comparisons with co-located CALIPSO products and GOES analyses will also be shown. The results are discussed in connection to the GPS radio occultation receiver which will be part of the Atomic Clock Ensemble in Space (ACES) payload...

  8. Laser fluorescence bronchoscope for localization of occult lung tumors

    Energy Technology Data Exchange (ETDEWEB)

    Profio, A.E.; Doiron, D.R.; King, E.G.

    1979-11-01

    A system for imaging occult bronchogenic carcinoma by the fluorescence of previously-injected, tumor-specific compound hematoporphyrin-derivative has been assembled and successfully used to locate a tumor l mm thick. The violet excitation source is a krypton ion laser coupled to fused quartz fiber light conductor. An electrostatic image intensifier attached to a standard flexible fiberoptic bronchoscope provides a bright image even at relatively low irradiance. A red secondary filter rejects most reflected background and autofluorescence. Sensitivity and contrast capability of the system should permit detection of a tumor less than 0.1 mm thick.

  9. Neurological deficit as a presentation of occult metastatic thyroid carcinoma.

    Science.gov (United States)

    Izzard, Mark; McIvor, Nicholas; Chaplin, John; Ianovski, Ilia

    2006-10-01

    Three cases of occult metastatic thyroid carcinoma presenting with neurological deficits are reviewed. In each case the patient's initial presentation was with symptoms of neurological deficiency secondary to a spinal cord compression. All patients received a combination of surgery, external beam radiotherapy and postoperative thyroxine treatment. Two of the three patients are alive and well, able to mobilize with minor neurological dysfunction. The diagnosis and management of the patients, as well as their outcomes are reviewed, with a discussion on further management issues alongside a review of the current published work.

  10. Occult hepatitis B infection and its possible impact on chronic hepatitis C virus infection

    Directory of Open Access Journals (Sweden)

    Habibollahi Peiman

    2009-01-01

    Full Text Available As a well-recognized clinical phenomenon, persistent detectable viral genome in liver or sera in the absence of other serological markers for active hepatitis B virus (HBV replication is called occult HBV infection. The main mechanism through which occult infection occurs is not completely understood and several possible explanations, such as integration into human genome and maintenance in peripheral mononuclear cells, exist. Occult HBV infection has been reported in different populations, especially among patients with Hepatitis C (HCV related liver disease. The probable impact of occult HBV in patients with chronic HCV infection has been previously investigated and the evidence suggests a possible correlation with lower response to anti-viral treatment, higher grades of liver histological changes, and also developing hepatocellular carcinoma. However, in the absence of conclusive results, further studies should be conducted to absolutely assess the impact of occult HBV contamination on the HCV related liver disease.

  11. James Webb Space Telescope Observations of Stellar Occultations by Solar System Bodies and Rings

    Science.gov (United States)

    Santos-Sanz, P.; French, R. G.; Pinilla-Alonso, N.; Stansberry, J.; Lin, Z-Y.; Zhang, Z-W.; Vilenius, E.; Mueller, Th.; Ortiz, J. L.; Braga-Ribas, F.; hide

    2016-01-01

    In this paper, we investigate the opportunities provided by the James Webb Space Telescope (JWST) for significant scientific advances in the study of Solar System bodies and rings using stellar occultations. The strengths and weaknesses of the stellar occultation technique are evaluated in light of JWST's unique capabilities. We identify several possible JWST occultation events by minor bodies and rings and evaluate their potential scientific value. These predictions depend critically on accurate a priori knowledge of the orbit of JWST near the Sun–Earth Lagrange point 2 (L2). We also explore the possibility of serendipitous stellar occultations by very small minor bodies as a byproduct of other JWST observing programs. Finally, to optimize the potential scientific return of stellar occultation observations, we identify several characteristics of JWST's orbit and instrumentation that should be taken into account during JWST's development.

  12. JWST observations of stellar occultations by solar system bodies and rings

    CERN Document Server

    Santos-Sanz, P; Pinilla-Alonso, N; Stansberry, J; Lin, Z-Y; Zhang, Z-W; Vilenius, E; Müller, Th; Ortiz, J L; Braga-Ribas, F; Bosh, A; Duffard, R; Lellouch, E; Tancredi, G; Young, L

    2015-01-01

    In this paper we investigate the opportunities provided by the James Webb Space Telescope (JWST) for significant scientific advances in the study of solar system bodies and rings using stellar occultations. The strengths and weaknesses of the stellar occultation technique are evaluated in light of JWST's unique capabilities. We identify several possible JWST occultation events by minor bodies and rings, and evaluate their potential scientific value. These predictions depend critically on accurate a priori knowledge of the orbit of JWST near the Sun-Earth Lagrange-point 2 (L2). We also explore the possibility of serendipitous stellar occultations by very small minor bodies as a by-product of other JWST observing programs. Finally, to optimize the potential scientific return of stellar occultation observations, we identify several characteristics of JWST's orbit and instrumentation that should be taken into account during JWST's development.

  13. Wave propagation simulation of radio occultations based on ECMWF refractivity profiles

    DEFF Research Database (Denmark)

    von Benzon, Hans-Henrik; Høeg, Per

    2015-01-01

    This paper describes a complete radio occultation simulation environment, including realistic refractivity profiles, wave propagation modeling, instrument modeling, and bending angle retrieval. The wave propagator is used to simulate radio occultation measurements. The radio waves are propagated...... of radio occultations. The output from the wave propagator simulator is used as input to a Full Spectrum Inversion retrieval module which calculates geophysical parameters. These parameters can be compared to the ECMWF atmospheric profiles. The comparison can be used to reveal system errors and get...... a better understanding of the physics. The wave propagation simulations will in this paper also be compared to real measurements. These radio occultations have been exposed to the same atmospheric conditions as the radio occultations simulated by the wave propagator. This comparison reveals that precise...

  14. Physical meaning and temporal variation of the zonal components of the geopotential

    Science.gov (United States)

    Varga, P.

    2003-04-01

    The generalized form of the MacCullagh representation is derived for zonal spherical harmonic coefficients J_n for degrees n >= 2 extending previous results for n=2 (Journal of Geodesy 74 (2000), 7-8, 519-530). It is shown that the even, zonal coefficients J_n can be represented with a difference of multiple moments C_n and A_n which are the volume integrals of the function of the density ρ, the distance from the centre of the Earth r^n and of the geographical coordinates (ϕ, λ) and because of their dependence of secular Love number k_s it enables us to compute the time derivatives partial^J/partial_t as the time derivative of J_n as well as the despinning rate of a deformable body like the Earth.

  15. Reversal and amplification of zonal flows by boundary enforced thermal wind

    CERN Document Server

    Dietrich, Wieland; Wicht, Johannes

    2016-01-01

    Zonal flows in rapidly-rotating celestial objects such as the Sun, gas or ice giants form in a variety of surface patterns and amplitudes. Whereas the differential rotation on the Sun, Jupiter and Saturn features a super-rotating equatorial region, the ice giants, Neptune and Uranus harbour an equatorial jet slower than the planetary rotation. Global numerical models covering the optically thick, deep-reaching and rapidly rotating convective envelopes of gas giants reproduce successfully the prograde jet at the equator. In such models, convective columns shaped by the dominant Coriolis force typically exhibit a consistent prograde tilt. Hence angular momentum is pumped away from the rotation axis via Reynolds stresses. Those models are found to be strongly geostrophic, hence a modulation of the zonal flow structure along the axis of rotation, e.g. introduced by persistent latitudinal temperature gradients, seems of minor importance. Within our study we stimulate these thermal gradients and the resulting ageos...

  16. Experimental and numerical study of mean zonal flows generated by librations of a rotating spherical cavity

    CERN Document Server

    Sauret, Alban; Morize, Cyprien; Bars, Michael Le; 10.1017/S0022112010004052

    2011-01-01

    We study both experimentally and numerically the steady zonal flow generated by longitudinal librations of a spherical rotating container. This study follows the recent weakly nonlinear analysis of Busse (2010), developed in the limit of small libration frequency - rotation rate ratio, and large libration frequency - spin-up time product. Using PIV measurements as well as results from axisymmetric numerical simulations, we confirm quantitatively the main features of Busse's analytical solution: the zonal flow takes the form of a retrograde solid body rotation in the fluid interior, which does not depend on the libration frequency nor on the Ekman number, and which varies as the square of the amplitude of excitation. We also report the presence of an unpredicted prograde flow at the equator near the outer wall.

  17. Zonal disintegration mechanism of isotropic rock masses around a deep spherical tunnel

    Institute of Scientific and Technical Information of China (English)

    谷新保; 毕靖; 许明

    2015-01-01

    In order to investigate zonal disintegration mechanism of isotropic rock masses around a deep spherical tunnel, a new mechanical model subjected to dynamic unloading under hydrostatic pressure condition is proposed. The total elastic stress-field distributions is determined using the elastodynamic equation. The effects of unloading rate and dynamic mechanical parameters of isotropic deep rock masses on the zonal disintegration phenomenon of the surrounding rock masses around a deep spherical tunnel as well as the total elastic stress field distributions are considered. The number and size of fractured and non-fractured zones are determined by using the Hoek-Brown criterion. Numerical computation is carried out. It is found from numerical results that the number of fractured zones increases with increasing the disturbance coefficient, in-situ stress, unloading time and unloading rate, and it decreases with increasing parameter geological strength index, the strength parameter and the uniaxial compressive strength of intact rock.

  18. Zonal overturning circulation and heat flux induced by heaving modes in the world oceans

    Institute of Scientific and Technical Information of China (English)

    TAN Wei; HUANG Rui Xin; WANG Weiqiang; WANG Xin

    2015-01-01

    Zonal overturning circulation (ZOC) and its associated zonal heat flux (ZHF) are important components of the oceanic circulation and climate system, although these conceptions have not received adequate attentions. Heaving induced by inter-annual and decadal wind stress perturbations can give rise to anomalous ZOC and ZHF. Based on a simple reduced gravity model, the anomalous ZOC and ZHF induced by idealized heaving modes in the world oceans are studied. For example, in a Pacific-like model basin intensified equatorial easterly on decadal time scales can lead to a negative ZOC with a non-negligible magnitude (–0.3×106 m3/s) and a considerable westward ZHF with an amplitude of –11.2 TW. Thus, anomalous ZOC and ZHF may consist of a major part of climate signals on decadal time scales and thus play an important role in the oceanic circulation and climate change.

  19. Interaction of moist convection with zonal jets on Jupiter and Saturn

    Science.gov (United States)

    Li, Liming; Ingersoll, Andrew P.; Huang, Xianglei

    2006-01-01

    Observations suggest that moist convection plays an important role in the large-scale dynamics of Jupiter's and Saturn's atmospheres. Here we use a reduced-gravity quasigeostrophic model, with a parameterization of moist convection that is based on observations, to study the interaction between moist convection and zonal jets on Jupiter and Saturn. Stable jets with approximately the same width and strength as observations are generated in the model. The observed zonal jets violate the barotropic stability criterion but the modeled jets do so only if the flow in the deep underlying layer is westward. The model results suggest that a length scale and a velocity scale associated with moist convection control the width and strength of the jets. The length scale and velocity scale offer a possible explanation of why the jets of Saturn are stronger and wider than those of Jupiter.

  20. Extent of partial ice cover due to carbon cycle feedback in a zonal energy balance model

    Directory of Open Access Journals (Sweden)

    C. Huntingford

    2003-01-01

    Full Text Available A global carbon cycle is introduced into a zonally averaged energy balance climate model. The physical model components are similar to those of Budyko (1969 and Sellers (1969. The new carbon components account for atmospheric carbon dioxide concentrations and the terrestrial and oceanic storage of carbon. Prescribing values for the sum of these carbon components, it is found that inclusion of a closed carbon cycle reduces the range of insolation over which stable partial ice cover solutions may occur. This highly simplified climate model also predicts that the estimated release of carbon from fossil fuel burning over the next hundred years could result in the eventual melting of the ice sheets. Keywords: climate, carbon cycle,zonal model, earth system modelling

  1. Zonal wavefront sensing using a grating array printed on a polyester film

    Energy Technology Data Exchange (ETDEWEB)

    Pathak, Biswajit; Boruah, Bosanta R., E-mail: brboruah@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati, Assam 781039 (India); Kumar, Suraj [Department of Applied Sciences, Gauhati University, Guwahati, Assam 781014 (India)

    2015-12-15

    In this paper, we describe the development of a zonal wavefront sensor that comprises an array of binary diffraction gratings realized on a transparent sheet (i.e., polyester film) followed by a focusing lens and a camera. The sensor works in a manner similar to that of a Shack-Hartmann wavefront sensor. The fabrication of the array of gratings is immune to certain issues associated with the fabrication of the lenslet array which is commonly used in zonal wavefront sensing. Besides the sensing method offers several important advantages such as flexible dynamic range, easy configurability, and option to enhance the sensing frame rate. Here, we have demonstrated the working of the proposed sensor using a proof-of-principle experimental arrangement.

  2. Linkage Between the Northeast Mongolian Precipitation and the Northern Hemisphere Zonal Circulation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The long-term relationship between the tree-ring-reconstructed annual precipitation in northeastern Mongolia (PRM) and the Northern Hemisphere Zonal Circulation (NHZC), defined as the normalized zonal mean sea-level pressure at 60°N in May-June-July, is examined in this study. A significant correlation coefficient (0.31) was found between the NHZC indices and PRM based on the dataset for the period of 1872-1995. The mechanisms responsible for the relationship are discussed through analyses of the atmospheric general circulation variability associated with NHZC. It follows that NHZC-related atmospheric circulation variability provides an anomalous southeast flow from the ocean to Northeast Mongolia (northwest flow from Northeast Mongolia to the ocean) in the middle and low troposphere in positive (negative) phase of NHZC, resulting in more (less) water vapor transport to the target region and more (less) precipitation in Northeast Mongolia.

  3. Characterization of the occult nature of injury for frequently occurring motor vehicle crash injuries.

    Science.gov (United States)

    Schoell, Samantha L; Doud, Andrea N; Weaver, Ashley A; Talton, Jennifer W; Barnard, Ryan T; Winslow, James E; Stitzel, Joel D

    2017-01-01

    Occult injuries are not easily detected and can be potentially life-threatening. The purpose of this study was to quantify the perceived occultness of the most frequent motor vehicle crash injuries according to emergency medical services (EMS) professionals. An electronic survey was distributed to 1,125 EMS professionals who were asked to quantify the likelihood that first responders would miss symptoms related to a particular injury on a 5-point Likert scale. The Occult Score for each injury was computed from the average of all the survey responses and normalized to be a continuous metric ranging from 0 to 1 where 0 is a non-occult (highly apparent on initial presentation) injury and 1 is an occult (unapparent on initial presentation) injury. Overall, 110,671 survey responses were collected. The Occult Score ranged from 0 to 1 with a mean, median, and standard deviation of 0.443, 0.450, and 0.233, respectively. When comparing the Occult Score of an injury to its corresponding AIS severity, there was no relationship between the metrics. When stratifying by body region, injury type, and AIS severity, it was evident that AIS 2-4 abdominal injuries with lacerations, hemorrhage, or contusions were perceived as the most occult injuries. Timely triage is key to reduce the morbidity and mortality associated with occult injuries. The Occult Score developed in this study to describe the predictability of an injury in a motor vehicle crash will be used as part of a larger effort, including incorporation into an advanced automatic crash notification (AACN) algorithm to detect crash conditions associated with a patient's need for prompt treatment at a trauma center. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Stationary Eddies and the Zonal Asymmetry of Net Precipitation and Ocean Freshwater Forcing

    OpenAIRE

    Wills, Robert C.; Schneider, Tapio

    2015-01-01

    Transport of water vapor in the atmosphere generates substantial spatial variability of net precipitation (precipitation minus evaporation). Over half of the total spatial variability in annual-mean net precipitation is accounted for by deviations from the zonal mean. Over land, these regional differences determine differences in surface water availability. Over oceans, they account, for example, for the Pacific–Atlantic difference in sea surface salinity, with implications for th...

  5. PV-θ view of the zonal mean state of the atmosphere

    Directory of Open Access Journals (Sweden)

    Aarnout J. Van Delden

    2012-08-01

    Full Text Available The relation between zonal mean potential vorticity (PV in potential temperature (θ coordinates and the zonal mean zonal wind in January and in July is studied. PV-anomalies are defined with respect to a reference state that is at rest with respect to the rotating earth. Two important PV-anomalies are identified. One PV-anomaly, the ‘Ex-UTLS PV-anomaly’, coincides approximately with the extratropical tropopause (310–360 K. It is a permanent feature of the zonal mean state. The other PV-anomaly is located higher in the stratosphere. It exhibits a strong seasonal cycle, i.e. in winter, it is strongly positive, while in summer, it is weakly negative. In the Northern Hemisphere winter, the Ex-UTLS PV-anomaly and the stratospheric PV-anomaly are separated by a ‘surf-zone’, which is characterised by a negative PV-anomaly pole-wards of a positive PV-anomaly. Piecewise PV-inversion reveals that (1 the Ex-UTLS PV-anomaly induces the westerly winds in the troposphere and the lower stratosphere, including the subtropical jet, that (2 the positive stratospheric PV-anomaly induces the stratospheric polar night jet and that (3 the negative polar cap stratospheric PV-anomaly in summer reduces the westerly wind speeds in the troposphere and induces easterly winds in the stratosphere. The Ex-UTLS PV-anomaly is manifest mainly as an isentropic density- (or mass- anomaly. Piecewise PV-inversion of these anomalies in isolation should account for this by an appropriate adjustment of the lower boundary condition.

  6. Semianalytical calculation of the zonal-flow oscillation frequency in stellarators

    Science.gov (United States)

    Monreal, Pedro; Sánchez, Edilberto; Calvo, Iván; Bustos, Andrés; Parra, Félix I.; Mishchenko, Alexey; Könies, Axel; Kleiber, Ralf

    2017-06-01

    Due to their capability to reduce turbulent transport in magnetized plasmas, understanding the dynamics of zonal flows is an important problem in the fusion program. Since the pioneering work by Rosenbluth and Hinton in axisymmetric tokamaks, it is known that studying the linear and collisionless relaxation of zonal flow perturbations gives valuable information and physical insight. Recently, the problem has been investigated in stellarators and it has been found that in these devices the relaxation process exhibits a characteristic feature: a damped oscillation. The frequency of this oscillation might be a relevant parameter in the regulation of turbulent transport, and therefore its efficient and accurate calculation is important. Although an analytical expression can be derived for the frequency, its numerical evaluation is not simple and has not been exploited systematically so far. Here, a numerical method for its evaluation is considered, and the results are compared with those obtained by calculating the frequency from gyrokinetic simulations. This ‘semianalytical’ approach for the determination of the zonal-flow frequency is revealed to be accurate and faster than the one based on gyrokinetic simulations.

  7. Zonal Detached-Eddy Simulation of Turbulent Unsteady Flow over Iced Airfoils

    KAUST Repository

    Zhang, Yue

    2015-07-23

    This paper presentsamultiscale finite-element formulation for the second modeofzonal detached-eddy simulation. The multiscale formulation corrects the lack of stability of the standard Galerkin formulation by incorporating the effect of unresolved scales to the grid (resolved) scales. The stabilization terms arise naturally and are free of userdefined stability parameters. Validation of the method is accomplished via the turbulent flow over tandem cylinders. The boundary-layer separation, free shear-layer rollup, vortex shedding from the upstream cylinder, and interaction with the downstream cylinder are well reproduced. Good agreement with experimental measurements gives credence to the accuracy of zonal detached-eddy simulation in modeling turbulent separated flows. A comprehensive study is then conducted on the performance degradation of ice-contaminated airfoils. NACA 23012 airfoil with a spanwise ice ridge and Gates Learjet Corporation-305 airfoil with a leading-edge horn-shape glaze ice are selected for investigation. Appropriate spanwise domain size and sufficient grid density are determined to enhance the reliability of the simulations. A comparison of lift coefficient and flowfield variables demonstrates the added advantage that the zonal detached-eddy simulation model brings to the Spalart-Allmaras turbulence model. Spectral analysis and instantaneous visualization of turbulent structures are also highlighted via zonal detached-eddy simulation. Copyright © 2015 by the CFD Lab of McGill University. Published by the American Institute of Aeronautics and Astronautics, Inc.

  8. The compressional beta effect: a source of zonal winds in planets?

    CERN Document Server

    Verhoeven, Jan

    2014-01-01

    Giant planets like Jupiter and Saturn feature strong zonal wind patterns on their surfaces. Although several different mechanisms that may drive these jets have been proposed over the last decades, the origin of the zonal winds is still unclear. Here, we explore the possibility that the interplay of planetary rotation with the compression and expansion of the convecting fluid can drive multiple deep zonal jets by a compressional Rhines-type mechanism, as originally proposed by Ingersoll and Pollard (1982). In a certain limit, this deep mechanism is shown to be mathematically analogous to the classical Rhines mechanism possibly operating at cloud level. Jets are predicted to occur on a compressional Rhines length $l_R = (2 \\Omega \\langle H_\\rho^{-1} \\rangle v_{jet}^{-1} )^{-1/2}$, where $\\Omega$ is the angular velocity, $\\langle H_\\rho^{-1} \\rangle$ is the mean inverse density scale height and $v_{jet}$ is the typical jet velocity. Two-dimensional numerical simulations using the anelastic approximation reveal ...

  9. Circulation response to ozone depletion depends on the zonal wind climatology

    Science.gov (United States)

    Lin, P.; Paynter, D.; Polvani, L. M.; Correa, G. J. P.; Ming, Y.; Ramaswamy, V.

    2016-12-01

    Circulation response to ozone depletion is studied in two General Climate Models: CAM3 and GFDL AM3. Both models are forced with identical ozone change and long time-slice simulations are performed to minimize the influence of internal variability. While both models simulate a lower stratospheric cooling and a poleward shift of extratropical jet with ozone depletion, the magnitudes of these changes are significantly different in the two models. The stronger stratospheric cooling simulated by CAM3 is due to a delayed onset of a negative dynamical feedback to polar stratospheric temperature changes, which is linked to its delayed breakdown of the polar vortex. By applying artificial zonal wind forcing to AM3 in the stratosphere, we are able to alter the zonal wind climatology over southern extratropical stratosphere in AM3 without directly affecting its own internal variability. This modified version of AM3 yields similar zonal wind climatology as CAM3. It also simulates stronger stratospheric cooling to the same ozone forcing compared to the original AM3. Since the delayed breakdown of the polar vortex is a common bias in most climate models, results of this study implies that the circulation response to ozone depletion simulated in most models might be overestimated.

  10. Gravity and Zonal Flows of Giant Planets: From the Euler Equation to the Thermal Wind Equation

    CERN Document Server

    Cao, Hao

    2015-01-01

    Any non-spherical distribution of density inside planets and stars gives rise to a non-spherical external gravity and change of shape. If part or all of the observed zonal flows at the cloud deck of giant planets represent deep interior dynamics, then the density perturbations associated with the deep zonal flows could generate gravitational signals detectable by the planned Juno mission and the Cassini Proximal Orbits. It is currently debated whether the thermal wind equation (TWE) can be used to calculate the gravity field associated with deep zonal flows. Here we present a critical comparison between the Euler equation and the thermal wind equation. Our analysis shows that the applicability of the TWE in calculating the gravity moments depends crucially on retaining the non-sphericity of the background density and gravity. Only when the background non-sphericity of the planet is taken into account, the TWE makes accurate enough prediction (with a few tens of percent errors) for the high-degree gravity mome...

  11. On the fast response of the Southern Ocean to changes in the zonal wind

    Directory of Open Access Journals (Sweden)

    D. J. Webb

    2007-09-01

    Full Text Available Model studies of the Southern Ocean, reported here, show that the Antarctic Circumpolar Current responds within two days to changes in the zonal wind stress at the latitudes of Drake Passage. Further investigation shows that the response is primarily barotropic and that, as one might expect, it is controlled by topography. Analysis of the results show that the changes in the barotropic flow are sufficient to transfer the changed surface wind stress to the underlying topography and that during this initial phase baroclinic processes are not involved.

    The model results also show that the Deacon Cell responds to changes in the wind stress on the same rapid time scale. It is shown that the changes in the Deacon Cell can also be explained by the change in the barotropic velocity field, an increase in the zonal wind stress producing an increased northward flow in shallow regions and southward flow where the ocean is deep. This new explanation is unexpected as previously the Deacon Cell has been thought of as a baroclinic feature of the ocean.

    The results imply that where baroclinic processes do appear to be involved in either the zonal momentum balance of the Southern Ocean or the formation of the Deacon Cell, they are part of the long term baroclinic response of the ocean's density field to the changes in the barotropic flow.

  12. Ex Luna Scientia: The Lunar Occultation Explorer (LOX)

    Science.gov (United States)

    Miller, Richard

    2017-01-01

    The Lunar Occultation Explorer (LOX) is a next-generation mission concept that provides new capabilities for time-domain astrophysics and established the Moon as a platform for nuclear astrophysics. Performance requirements are driven by Type-Ia supernova (SNeIa) science goals that seek to revel details of these profoundly radioactive objects, including their diversity. Primary science objectives include, but are not limited to, probing the fundamental thermonuclear physics processes, performing a census of progenitors and their explosion mechanisms, and evaluating the environmental conditions and intrinsic systematics of these enigmatic objects. LOX provides new capabilities for all-sky, continuous monitoring in the MeV regime (0.1-10 MeV) by leveraging the Lunar Occultation Technique (LOT). Key benefits of the LOX/LOT approach include maximizing the ratio of sensitive-to-total deployed mass, low implementation risk, and demonstrated operational simplicity that leverages extensive experience with planetary orbital geochemistry investigations; LOX also enables long-term monitoring of MeV gamma-ray sources, a critical capability for SNeIa science. Proof-of-principle efforts validated all aspects of the mission using previously deployed lunar science assets, and led to the first high-energy gamma-ray source detected at the Moon. LOX mission performance, development progress, and expectations for science investigations will be presented.

  13. Dust occultation at Titan measured by CDA onboard Cassini

    Science.gov (United States)

    Srama, Ralf; CDA science Team

    2016-10-01

    The Cosmic Dust Analyzer (CDA) onboard Cassini characterized successfully the dust environment at Saturn since 2004. The instrument measures the primary charge, speed, mass and composition of individual submicron and micron sized dust grains. The detection threshold scales with speed^3.5 such that the detection of fast nanograins (~100 km/s) is possible. Saturn's nanodust environment (streams) is studied many years. However, a special geometric condition of Saturn, Cassini and Titan during a Titan flyby in 2014 (DOY 65) provided a special dust occultation opportunity. Titan and its atmosphere blocked the stream of fast nanoparticles such that CDA registered a clear drop in impact rate around closest approach. An analysis of the data allows to constrain the source region of the nanograins, which is compatible with a source region in the ring plane at distances from Saturn between 4 and 8 Saturn radii. Backward and forward modeling was performed leading to dust grain sizes between 3 and 9 nm and speeds between 80 and 150 km/s. The new modeling results also show that Enceladus acts a direct source for nanodust streams leading to the observation of periodic impact rates in the outer Saturn system. Such periodicities were observed recently by CDA and showed a clear signature of the Enceladus orbital period. A second dust occultation opportunity using Titan is planned august 2016.

  14. Ionospheric Behaviour Analysis over Thailand Using Radio Occultation Technique.

    Directory of Open Access Journals (Sweden)

    Ahmed Wasiu Akande

    2015-11-01

    Full Text Available With the advent in the development of science and technology in the field of space and atmospheric science in order to obtain accurate result, hence the use of radio occultation technique in the investigation of the amount of electron density and Total Electron Content presence in equatorial region particularly over Thailand. In this research, radio occultation data obtained from UCAR/CDAAC was used to observe daily, monthly, seasonal and the entire year 2013 Ionospheric TEC and electron density variation due to changes and instability of solar activities from time to time. It was observed that TEC was high (ionosphere was more disturbed or violent in May and spread over a wide range of altitude and summer season has the highest TEC value for the year 2013 which means at this period GNSS measurements was more prone to error. It was noted that ionospheric variations or fluctuations was maximum between 200km and 450km altitude. The results of the study show that ionospheric perturbation effects or irregularities depend on season and solar activity.

  15. Comet plasma densities deduced from refraction of occulted radio sources

    Energy Technology Data Exchange (ETDEWEB)

    Wright, C.S. (Commonwealth Department of Science, Ionospheric Prediction Service, Narrabri, New South Wales, Australia); Nelson, G.J. (Commonwealth Scientific and Industrial Research Organization, Div. of Radiophysics, Narrabri, New South Wales, Australia)

    1979-04-01

    Observations of the occultation of radio sources by comet plasma tails are used to derive the electron density and density gradients in the tails. Occultations of source Culgoora-1 0300+16 by Comet Kohoutek and of Culgoora-1 2313-14 by Comet West were measured by radioheliograph at 80 MHz. After corrections for ionospheric refraction, a 2 arcmin anomaly was observed in the declination of 0300+16, attributed to refraction by the tail of Comet Kohoutek, while none was observed for Comet West. The maximum electron density in the tail of Comet Kohoutek is calculated to be 2 x 10 to the 4th/cu cm, while that of Comet West is 5 x 10 to the 4th/cu cm, with density gradients of about 0.05 per cu cm per km. The direction of refraction observed suggests that the tail of Kohoutek is either highly asymmetric about its axis or has the form of a hollow, cylindrical plasma sheath. The high electron densities observed in Kohoutek may indicate the presence of undetected ion species or a low ionization loss rate.

  16. CT herniography in the diagnosis of occult groin hernias

    Energy Technology Data Exchange (ETDEWEB)

    Markos, V. [Department of Radiology, Gloucester Royal Hospital, Gloucester (United Kingdom)]. E-mail: vmarkos@hotmail.com; Brown, E.F. [Department of Radiology, Gloucester Royal Hospital, Gloucester (United Kingdom)

    2005-02-01

    AIM: To evaluate the role of computed tomography (CT) after herniography in the diagnosis and management of primary and recurrent groin hernias not detectable on clinical examination. MATERIAL AND METHODS: Fifty-one patients underwent CT post-herniography over a 6-year period for suspected primary or recurrent inguinal hernia. The herniography and post-herniography CT findings were retrospectively compared with clinical and surgical follow-up. Statistical analysis was performed to assess the role of herniography and CT post-herniography in the primary and recurrent groups. RESULTS: Of the 51 patients investigated for occult inguinal hernia, 19 had previous hernia repair with possible recurrence. The most common symptom at presentation was groin pain or discomfort (84%). Seventy-five percent in the primary group and 84% in the recurrent group had no findings on herniography or CT. Nine percent in the primary group and 16% in the recurrent group had hernias diagnosed by herniography. CT did not enhance the detection of hernia. Sensitivity for herniography and CT herniography in the primary groin hernia group was 75% as against specificity, which was 100 and 90%, respectively. For the recurrent groin hernias, sensitivity was 60% for herniography and 40% for CT herniography and specificity 100% for both. CONCLUSION: CT performed post-herniography did not provide any benefit over performing herniography alone in the diagnosis of occult primary or recurrent inguinal hernias.

  17. Insensible and Inexplicable - On the Two Meanings of Occult

    Directory of Open Access Journals (Sweden)

    Florian Sprenger

    2015-09-01

    Full Text Available While the distinction between spiritualism and science was understood affirmatively as a demarcation of true science against pseudo-science, nowadays, after several Science Wars, it is obvious for us that this distinction does not correspond to the actual practices of science but reflects a work of ‘purification’ typical for modernity in the Latourian sense. In the physico-philosophical surroundings of this boundary epistemological foundations are shaped and modern science is constituted as the primary way to knowledge. Referring to studies on the history of the occult in the early modern period, the article shows that in order to understand the stakes of spiritualism and its technical or personal media we should trace back this boundary to a rarely recognized conceptual transformation of the ‘occult’. It shifts between insensible and inexplicable. Following this leading difference, the article traces its function in the emergence of early occultism, the debate between Leibniz and Newton, and the rise of modern spiritualism and its instrumental repertoire.

  18. PREVALENCE OF OCCULT DEPRESSION IN ELDERLY WITH CHRONIC CO - MORBIDS

    Directory of Open Access Journals (Sweden)

    Sachin

    2015-02-01

    Full Text Available BACKGROUND: Growth in elderly population has led to an increase in age related diseases and mainly depression which is affecting the quality of life. Depression is more prevalent amongst elderly individuals with medical illnesses and emerging public health problem leading to increased morbidity and disability worldwide. AIMS AND OBJE CTIVES: To assess the prevalence of occult depression in elderly patients with chronic co - morbid medical conditions. MATERIALS AND METHODS: It was a cross - sectional study conducted in tertiary hospital. Total 100 elderly patients with underlying chronic me dical illnesses were included. Depression in study population was assessed by geriatric depression scale and analyzed. RESULT: Out of 100 patients 23(23% had depression. Females 12/39(30.76% were affected more than males 11/61 (18.03%. Depression was mo re prevalent among patients with 3 or more co - morbid conditions (45.4% as compared to <3 (11.9%. CONCLUSION: Elderly patients with multiple chronic medical illnesses may have associated occult depression. Screening of these patients for depression couple d with appropriate psychiatric referral should be an integral part of Geriatric service

  19. Processing and validation of refractivity from GRAS radio occultation data

    Directory of Open Access Journals (Sweden)

    K. B. Lauritsen

    2011-04-01

    Full Text Available We discuss the processing of GRAS radio occultation (RO data done at the GRAS Satellite Application Facility. The input data consists of operational near-real time bending angles from December 2010 from the Metop-A satellite operated by EUMETSAT. The data are processed by an Abel inversion algorithm in combination with statistical optimization based on a two-parameter fit to an MSIS climatology. We compare retrieved refractivity to analyses from ECMWF. It is found that for global averages, the mean differences to ECMWF analyses are smaller than 0.2% below 30 km (except near the surface, with standard deviations around 0.5% for altitudes between 8 and 25 km. The current processing is limited by several factors, which are discussed. In particular, the penetration depth for rising occultations is generally poor, which is related to the tracking of the L2 signal. Extrapolation of the difference between the L1 and L2 signals below the altitude where L2 is lost is possible and would generally allow deeper penetration of retrieved refractivity profiles into the lower troposphere.

  20. Processing and validation of refractivity from GRAS radio occultation data

    Directory of Open Access Journals (Sweden)

    K. B. Lauritsen

    2011-10-01

    Full Text Available We discuss the processing of GRAS radio occultation (RO data done at the GRAS Satellite Application Facility. The input data consists of operational near-real time bending angles from December 2010 from the Metop-A satellite operated by EUMETSAT. The data are processed by an Abel inversion algorithm in combination with statistical optimization based on a two-parameter fit to an MSIS climatology. We compare retrieved refractivity to analyses from ECMWF. It is found that for global averages, the mean differences to ECMWF analyses are smaller than 0.2% below 30 km (except near the surface, with standard deviations around 0.5% for altitudes between 8 and 25 km. The current processing is limited by several factors, which are discussed. In particular, the penetration depth for rising occultations is generally poor, which is related to the tracking of the L2 signal. Extrapolation of the difference between the L1 and L2 signals below the altitude where L2 is lost is possible and would generally allow deeper penetration of retrieved refractivity profiles into the lower troposphere.

  1. Detection of Small Kuiper Belt Objects by Stellar Occultations

    CERN Document Server

    Stevenson, R

    2007-01-01

    Knowledge of the Kuiper Belt is currently limited to those objects that can be detected directly. Objects with diameters less than $\\sim$10km reflect too little light to be detected. These smaller bodies could contain most of the mass in the Kuiper Belt while the abundance of these bodies may constrain the distribution of mass. The overall size distribution of bodies within the Kuiper Belt can also be inferred from the relative abundances of sub-km and larger bodies. Stellar occultations are already used to study dark objects in the Solar System, such as asteroids or planetary rings. Occultation by a KBO of a size comparable to, or larger than, that of the Fresnel Scale will result in Fresnel diffraction. Detection of diffraction effects requires fast multiple-star photometry, which will be conducted in July 2007 using the Orthogonal Parallel Transfer Imaging Camera (OPTIC) mounted on the University of Hawaii 2.2m telescope on Mauna Kea. This paper details how knowledge of the mass and structure of the outer ...

  2. Waves in the Martian Atmosphere: Results from MGS Radio Occultations

    Science.gov (United States)

    Flasar, F. M.; Hinson, D. P.; Tyler, G. L.

    1999-09-01

    Temperatures retrieved from Mars Global Surveyor radio occultations have been searched for evidence of waves. Emphasis has been on the initial series of occultations between 29(deg) N and 64(deg) S, obtained during the early martian southern summer, L_s=264(deg-308^deg) . The profiles exhibit an undulatory behavior that is suggestive of vertically propagating waves. Wavelengths ~ 10 km are often dominant, but structure on smaller scales is evident. The undulatory structure is most pronounced between latitudes 29(deg) N and 10(deg) S, usually in regions of ``interesting'' topography, e.g., in the Tharsis region and near the edge of Syrtis Major. Several temperature profiles, particularly within 30(deg) of the equator, exhibit lapse rates that locally become superadiabatic near the 0.4--mbar level or at higher altitudes. This implies that the waves are ``breaking'' and depositing horizontal momentum into the atmosphere. Such a deposition may play an important role in modulating the atmospheric winds, and characterizing the spatial and temporal distribution of these momentum transfers can provide important clues to understanding how the global circulation is maintained.

  3. Occult hepatitis B virus infection and blood transfusion

    Institute of Scientific and Technical Information of China (English)

    Dong Hee Seo; Dong Hee Whang; Eun Young Song; Kyou Sup Han

    2015-01-01

    Transfusion-transmitted infections including hepatitis Bvirus (HBV) have been a major concern in transfusionmedicine. Implementation of HBV nucleic acid testing(NAT) has revealed occult HBV infection (OBI) in blooddonors. In the mid-1980s, hepatitis B core antibody(HBc) testing was introduced to screen blood donorsin HBV non-endemic countries to prevent transmissionof non-A and non-B hepatitis. That test remains inuse for preventing of potential transmission of HBVfrom hepatitis B surface antigen (HBsAg)-negativeblood donors, even though anti-hepatitis C virus testshave been introduced. Studies of anti-HBc-positivedonors have revealed an HBV DNA positivity rate of0%-15%. As of 2012, 30 countries have implementedHBV NAT. The prevalence of OBI in blood donors wasestimated to be 8.55 per 1 million donations, accordingto a 2008 international survey. OBI is transmissible byblood transfusion. The clinical outcome of occult HBVtransmission primarily depends on recipient immunestatus and the number of HBV DNA copies present in theblood products. The presence of donor anti-HBs reducesthe risk of HBV infection by approximately five-fold. Therisk of HBV transmission may be lower in endemic areasthan in non-endemic areas, because most recipientshave already been exposed to HBV. Blood safety forHBV, including OBI, has substantially improved, but thepossibility for OBI transmission remains.

  4. Observations of Three Stellar Occultations by Comet Hale-Bopp

    Science.gov (United States)

    Betzler, A. S.; Betzler, L. B. S.

    2017-03-01

    On June 12 1996 UT, three 11-12 R magnitude stars were occulted by comet Hale-Bopp. The passage of these stars through the cometary atmosphere was monitored at the Observatorio do Pico dos Dias (Brazil) using a 0.6 m telescope. We detected an absorption of starlight by the comet dust implying in a drop of (6± 1) × 10^{-2} magnitude of occulted star XPM 152-0898466 at a minimum distance of (4.3 ± 0.2)× 104 km from the central condensation. This result, combined with magnitude variations of other stars, suggests the detection of a jet in the coma. From our measurement of extinction, we infer that the opacity of the nucleus surface was τ ˜ 3 . The mean geometric albedo p of dust grains is (4.5 ± 0.7) × 10^{-3} . This low albedo may suggest a difference in the grain population associated to coma and jets.

  5. 'Trick', 'manipulation' and 'farce': Albert Moll's critique of occultism.

    Science.gov (United States)

    Wolffram, Heather

    2012-04-01

    In July 1925, the psychiatrist Albert Moll appeared before the district court in Berlin-Schöneberg charged with having defamed the medium Maria Vollhardt (alias Rudloff) in his 1924 book Der Spiritismus [Spiritism]. Supported by some of Berlin's most prominent occultists, the plaintiff--the medium's husband--argued that Moll's use of terms such as 'trick', 'manipulation' and 'farce' in reference to Vollhardt's phenomena had been libellous. In the three-part trial that followed, however, Moll's putative affront to the medium--of which he was eventually acquitted--was overshadowed, on the one hand, by a debate over the scientific status of parapsychology, and on the other, by the question of who--parapsychologists, occultists, psychiatrists or jurists--was entitled to claim epistemic authority over the occult. This paper will use the Rudloff-Moll trial as a means of examining Moll's critique of occultism, not only as it stood in the mid-1920s, but also as it had developed since the 1880s. It will also provide insight into the views of Germany's occultists and parapsychologists, who argued that their legitimate bid for scientific credibility was hindered by Dunkelmänner [obscurantists] such as Albert Moll.

  6. Stargazing from New Horizons: Ultraviolet Stellar Occultations by Pluto's Atmosphere

    Science.gov (United States)

    Kammer, Joshua A.; Stern, S. Alan; Weaver, Harold A.; Young, Leslie; Ennico, Kimberly; Olkin, Catherine B.; Gladstone, Randy; Summers, Michael; Steffl, Andrew; Greathouse, Thomas K.; Versteeg, Maarten; Retherford, Kurt D.; Parker, Joel Wm.; Schindhelm, Eric; Strobel, Darrell F.; New Horizons ATM Theme Team, New Horizons Science Team

    2016-10-01

    Not long after the New Horizons encounter with Pluto last July, the Alice ultraviolet imaging spectrograph observed signatures of UV absorption by Pluto's atmosphere during two distinct occultation events. During these events, UV bright stars (the Sun, as well as two B-type stars) passed behind Pluto as seen by the spacecraft, and the attenuated starlight revealed the clear presence of nitrogen, methane, and several other hydrocarbons. Their mixing ratios vary with altitude, including localized peaks in the density of minor hydrocarbons such as C2H2 and C2H4. At about 300 km above Pluto's surface, these particular species are found to have mixing ratios relative to CH4 of approximately 10% and 1%, respectively. While this overall composition was expected pre-New Horizons, the vertical profiles of these species were surprising. In this presentation I will discuss the analysis of these occultations, including several profiles of key atmospheric species, and how they might play a role in explaining the presence of high-altitude haze on this cold, small, distant planet.

  7. Occulting Light Concentrators in Liquid Scintillator Neutrino Detectors

    Science.gov (United States)

    Buizza Avanzini, Margherita; Cabrera, Anatael; Dusini, Stefano; Grassi, Marco; He, Miao; Wu, Wenjie

    2017-09-01

    The experimental efforts characterizing the era of precision neutrino physics revolve around collecting high-statistics neutrino samples and attaining an excellent energy and position resolution. Next generation liquid-based neutrino detectors, such as JUNO, HyperKamiokande, etc, share the use of a large target mass, and the need of pushing light collection to the edge for maximal calorimetric information. Achieving high light collection implies considerable costs, especially when considering detector masses of several kt. A traditional strategy to maximize the effective photo-coverage with the minimum number of PMTs relies on Light Concentrators (LC), such as Winston Cones. In this paper, the authors introduce a novel concept called Occulting Light Concentrators (OLC), whereby a traditional LC gets tailored to a conventional PMT, by taking into account its single-photoelectron collection efficiency profile and thus occulting the worst performing portion of the photocathode. Thus, the OLC shape optimization takes into account not only the optical interface of the PMT, but also the maximization of the PMT detection performances. The light collection uniformity across the detector is another advantage of the OLC system. By considering the case of JUNO, we will show OLC capabilities in terms of light collection and energy resolution.

  8. Comparison of ionospheric radio occultation CHAMP data with IRI 2001

    Directory of Open Access Journals (Sweden)

    N. Jakowski

    2004-01-01

    Full Text Available GPS radio occultation measurements on board low Earth orbiting satellites can provide vertical electron density profiles of the ionosphere from satellite orbit heights down to the bottomside. Ionospheric radio occultation (IRO measurements carried out onboard the German CHAMP satellite mission since 11 April 2001 were used to derive vertical electron density profiles (EDP’s on a routine basis. About 150 vertical electron density profiles may be retrieved per day thus providing a huge data basis for testing and developing ionospheric models. Although the validation of the EDP retrievals is not yet completed, the paper addresses a systematic comparison of about 78 000 electron density profiles derived from CHAMP IRO data with the International Reference Ionosphere (IRI 2001. The results are discussed for quite different geophysical conditions, e.g. as a function of latitude, local time and geomagnetic activity. The comparison of IRO data with corresponding IRI data indicates that IRI generally overestimates the upper part of the ionosphere whereas it underestimates the lower part of the ionosphere under high solar activity conditions. In a first order correction this systematic deviation could be compensated by introducing a height dependence correction factor in IRI profiling.

  9. Wind Diffusivity Current, QuikSCAT SeaWinds, 0.25 degrees, Global, Science Quality, Zonal

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes science quality Ekman current (in zonal, meridional, and modulus sets) and Ekman upwelling data. This data begins with wind velocity...

  10. Rossby and Drift Wave Turbulence and Zonal Flows: the Charney-Hasegawa-Mima model and its extensions

    CERN Document Server

    Connaughton, Colm; Quinn, Brenda

    2014-01-01

    A detailed study of the Charney-Hasegawa-Mima model and its extensions is presented. These simple nonlinear partial differential equations suggested for both Rossby waves in the atmosphere and also drift waves in a magnetically-confined plasma exhibit some remarkable and nontrivial properties, which in their qualitative form survive in more realistic and complicated models, and as such form a conceptual basis for understanding the turbulence and zonal flow dynamics in real plasma and geophysical systems. Two idealised scenarios of generation of zonal flows by small-scale turbulence are explored: a modulational instability and turbulent cascades. A detailed study of the generation of zonal flows by the modulational instability reveals that the dynamics of this zonal flow generation mechanism differ widely depending on the initial degree of nonlinearity. A numerical proof is provided for the extra invariant in Rossby and drift wave turbulence -zonostrophy and the invariant cascades are shown to be characterised...

  11. Wind Diffusivity Current, QuikSCAT SeaWinds, 0.25 degrees, Global, Science Quality, Zonal

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes science quality Ekman current (in zonal, meridional, and modulus sets) and Ekman upwelling data. This data begins with wind velocity...

  12. Management of occult hepatitis B virus infection: An update for the clinician

    Institute of Scientific and Technical Information of China (English)

    José Luis Lledó; Conrado Fernández; María Luisa Gutiérrez; Sara Oca(n)a

    2011-01-01

    Occult hepatitis B virus (HBV) infection (OBI) is defined by the presence of HBV DNA in the liver tissue of individuals who test negative for hepatitis B surface antigen (HBsAg). Patients who have recovered from acute hepatitis B can carry HBV genomes for a long time and show histological patterns of mild necro-inflammation, even fibrosis, years after the resolution of acute hepatitis, without showing any clinical or biochemical evidence of liver disease. At least in conditions of immunocompetence, OBI is inoffensive itself, but when other relevant causes of liver damage are present it might make the course of the liver disease worse. The risk of HBV transmission through transfusion is related to blood donations negative for HBsAg that have been collected during the pre-seroconversion period or during chronic OBI. Use of HBV nucleic acid amplification testing and multivalent anti-HBs antibodies in the HBsAg assays is recommended for detection of true and false OBI, respectively. It is not known if prior hepatitis B immunization with an optimal anti-HBs response in cases of HBV transmission through organ transplantation can effectively modulate or abort the infection. Use of antiviral agents as prophylaxis in patients with serological evidence of past HBV infection prevents reactivation of OBI after transplantation in most cases. s been observed in other conditions that cause immunosuppression, in which antiviral therapy could be delayed until the HBV DNA or HBsAg becomes detectable. OBI might contribute to the progression of liver fibrosis and hepatocellular carcinoma development in patients with chronic liver disease.

  13. Changes in equatorial zonal circulations and precipitation in the context of the global warming and natural modes

    Science.gov (United States)

    Kim, Byeong-Hee; Ha, Kyung-Ja

    2017-07-01

    The strengthening and westward shift of Pacific Walker Circulation (PWC) is observed during the recent decades. However, the relative roles of global warming and natural variability on the change in PWC unclearly remain. By conducting numerical atmospheric general circulation model (AGCM) experiments using the spatial SST patterns in the global warming and natural modes which are obtained by the multi-variate EOF analysis from three variables including precipitation, sea surface temperature (SST), and divergent zonal wind, we indicated that the westward shift and strengthening of PWC are caused by the global warming SST pattern in the global warming mode and the negative Interdecadal Pacific Oscillation-like SST pattern in the natural mode. The SST distribution of the Pacific Ocean (PO) has more influence on the changes in equatorial zonal circulations and tropical precipitation than that of the Indian Ocean (IO) and Atlantic Ocean (AO). The change in precipitation is also related to the equatorial zonal circulations variation through the upward and downward motions of the circulations. The IO and AO SST anomalies in the global warming mode can affect on the changes in equatorial zonal circulations, but the influence of PO SST disturbs the changes in Indian Walker Circulation and Atlantic Walker Circulation which are affected by the anomalous SST over the IO and AO. The zonal shift of PWC is found to be highly associated with a zonal gradient of SST over the PO through the idealized numerical AGCM experiments and predictions of CMIP5 models.

  14. [A retrospective analysis on occult neck lymphatic metastasis in early tongue cancer].

    Science.gov (United States)

    Gong, Q L; Bian, C; Liu, H

    2016-10-07

    Objective: To investigate the number and level of occult neck lymphatic metastasis for squamous cell carcinoma of tongue in clinical stage Ⅰ/Ⅱ, and the relationship between cell differentiation and occult neck lymphatic metastasis. Methods: A total of 101 cases diagnosed preoperatively as having squamous cell carcinoma of tongue in clinical stage Ⅰ/Ⅱ (cT1/T2N0M0) between January 2005 and April 2015 were analysed retrospectively. Whether presence of occult neck lymphatic metastasis in these cases was studied. Results: Occult neck lymphatic metastases were found in 22 (21.78%) of 101 cases, 10 men and 12 women, with an age range of 22 to 83 years. There was not statistically significant association between tumor size or cell differentiation and occult neck lymphatic metastasis (P>0.05). The metastasis occurred most commonly in level Ⅱ, followed by levelsⅠ, Ⅲ and Ⅳ. There was no lymph node metastasis in Level Ⅴ. There were total 20 cases with occult neck lymphatic metastasis in at least one of levelⅠ, Ⅱ, Ⅲ(90.9%), One of these case was skipping metastasis in level Ⅲ(4.6%). Conclusion: The early tongue cancer has a high rate of occult lymph metastasis, which occurs commonly in levels Ⅱ, Ⅰ and Ⅲ, but there is not significant association between the metastasis and tumor size or cell differentiation.

  15. All-Sky Earth Occultation Observations with the Fermi Gamma Ray Burst Monitor

    Science.gov (United States)

    Wilson-Hodge, C. A.; Beklen, E.; Bhat, P. N.; Briggs, M.; Camero-Arranz, A.; Case, G.; Chaplin, V.; Cherry, M.; Connaughton, V.; Finger, M.; Jenke, P.; Paciesas, W.; Preece, R.; Rodi, J.

    2010-01-01

    Using the Gamma Ray Burst Monitor (GBM) on-board Fermi, we are monitoring the hard X-ray/soft gamma ray sky using the Earth occultation technique. Each time a source in our catalog is occulted by (or exits occultation by) the Earth, we measure its flux using the change in count rates due to the occultation. Currently we are using CTIME data with 8 energy channels spanning 8 keV to 1 MeV for the GBM NaI detectors and spanning 150 keV to 40 MeV for the GBM BGO detectors. Our preliminary catalog consists of galactic X-ray binaries, the Crab Nebula, and active galactic nuclei. New sources are added to our catalog as they become active or upon request. In addition to Earth occultations, we have observed numerous occultations with Fermi's solar panels. We will present early results. Regularly updated results will be found on our website http://gammaray.nsstc.nasa.gov/gbm/science/occultation.

  16. A pareto-optimal characterization of miniaturized distributed occulter/telescope systems

    Science.gov (United States)

    Koenig, Adam W.; D'Amico, Simone; Macintosh, Bruce; Titus, Charles J.

    2015-09-01

    Distributed occulter/telescope systems hold great promise in the field of direct exoplanet imaging. However, proposed missions using this concept such as the New Worlds Observer or Exo-S (NASA) are exceptionally large with occulter diameters of tens of meters and inter-spacecraft separations of tens of megameters, requiring deployment in deep space. The estimated costs associated with these missions are in the billions of dollars. In order to reduce the risk associated with these missions, it is desirable to first deploy a low-cost technology demonstrator mission to prove that the distributed occulter telescope concept is valid. To that end, this work assesses the feasibility of miniaturizing the optics of the distributed occulter/telescope to enable deployment on micro- or nano-satellites in earth orbit. A variant of the convex optimization formulation introduced by previous authors is used to generate a pareto-optimal characterization between the achievable occulter contrast and a set of critical design variables (occulter radius, inner working angle, science spectrum, etc). This characterization is performed for two different sets of engineering constraints, corresponding to different levels of design complexity. The results of this study are compared to the performance requirements for imaging targets of scientific interest, namely exozodiacal dust disks, in order to identify promising design envelopes. The result of this work is a comprehensive trade of the capabilities of miniaturized, binary, petal-shaped occulters. This research demonstrates that there exist miniaturized occulter geometries compatible with micro- or nano-satellites in earth orbit suitable for imaging exozodiacal dust disks. In addition, this study provides a valuable methodology and performance guidelines for future distributed occulter/telescope designs.

  17. Detection of occult endocervical glandular dysplasia in cervical conization specimens for squamous lesions.

    Science.gov (United States)

    Sopracordevole, F; Clemente, N; Alessandrini, L; Di Giuseppe, J; Cigolot, F; Buttignol, M; Ciavattini, A; Canzonieri, V

    2017-03-01

    The aim of this work was to evaluate the incidence of occult cervical glandular intraepithelial neoplasia (CGIN) and adenocarcinoma of the cervix (AC) in women treated with CO2-laser conization for cervical intraepithelial neoplasia (CIN) or squamocellular cervical cancer (SCC). The medical records of all women with a histological diagnosis of squamous lesions of the uterine cervix (persistent CIN1, CIN2, CIN3 and SCC) who were subsequently treated with CO2-laser conization at our institution, during the period from January 1991 to December 2014, were analyzed in a retrospective case series. Among the 1004 women fulfilling the study inclusion/exclusion criteria, 77 cases (7.7%) of occult glandular lesions (CGIN and AC) were detected on the final cone specimen (48 cases of occult low-grade cervical glandular intraepithelial neoplasia (LCGIN), 25 cases of occult high-grade cervical glandular intraepithelial neoplasia (HCGIN), and four cases of occult "usual-type" AC). No difference in the mean age between women diagnosed with occult glandular lesions and women without occult glandular lesions on the final specimen emerged (39.1±9.3 vs 38.4±9.4, p=0.5). In women with occult LCGIN on cone specimen, mean follow-up of 48 months was reported (range 7-206 months) and no cases of progression to HCGIN or AC were observed. In conclusion, a relatively high rate of occult glandular lesions was found in women treated for squamous lesions. The natural history of CGIN is still uncertain and, in particular, there are some controversies as to whether LCGIN is a precursor lesion of HCGIN or AC. In this context the role of pathologists become very important since the appropriate diagnosis of these lesions could have potential implications in the clinical management of these patients.

  18. Central Flash Analysis of the 29 June 2015 Occultation

    Science.gov (United States)

    Person, Michael J.; Bosh, A. S.; Sickafoose, A. A.; Zuluaga, C. A.; Levine, S. E.; Pasachoff, J. M.; Babcock, B. A.; Dunham, E. W.; McLean, I.; Wolf, J.; Abe, F.; Becklin, E.; Bida, T. A.; Bright, L. P.; Brothers, T. C.; Christie, G.; Collins, P. L.; Durst, R. F.; Gilmore, A. C.; Hamilton, R.; Harris, H. C.; Johnson, C.; Kilmartin, P. M.; Kosiarek, M. R.; Leppik, K.; Logsdon, S. E.; Lucas, R.; Mathers, S.; Morley, C. J. K.; Natusch, T.; Nelson, P.; Ngan, H.; Pfueller, E.; Roeser, H.-P.; Sallum, S.; Savage, M.; Seeger, C. H.; Siu, H.; Stockdale, C.; Suzuki, D.; Thanathibodee, T.; Tilleman, T.; Tristram, P. J.; Van Cleeve, J.; Varughese, C.; Weisenbach, L. W.; Widen, E.; Wiedemann, M.

    2015-11-01

    After an extensive prediction effort, the 29 June 2015 occultation by Pluto was observed from both airborne (Stratospheric Observatory for Infrared Astronomy - SOFIA) and numerous ground-based telescopes (Bosh et al. - this meeting). Real-time prediction updates allowed placement of the SOFIA telescope with its four detectors deep within the central-flash region of the atmospheric occultation. Fortuitously, the Mount John University Observatory (Lake Tekapo, New Zealand) was also within the central-flash region (Pasachoff et al. - this meeting). This happenstance resulted in multiple central-flash detections in several colors from each facility allowing direct comparison of different areas of the central-flash evolute.Here we examine and discuss the central-flash signatures from the highest signal-to-noise light curves from each facility. The relative orientations and asymmetries in the central flashes allow us to use them to tightly constrain the lower atmospheric ellipticity and orientation of likely winds with respect to Pluto’s figure. The ratio of the two separate central flashes is also a strong constraint on the geometric solution for the full occultation data set, and the absolute height of the central flashes with respect to those expected for a clear isothermal atmosphere places constraints on haze densities and thermal gradients in Pluto’s lower atmosphere. We can also compare the central-flash signatures in several colors (similar to Sickafoose et. al - this meeting) to establish bounds on haze-particle sizes in the lower atmosphere.SOFIA is jointly operated by the Universities Space Research Association, Inc. (USRA), under NASA contract NAS2-97001, and the Deutsches SOFIA Institut (DSI) under DLR contract 50 OK 0901 to the University of Stuttgart. Support for this work was provided, in part, by NASA grants SSO NNX15AJ82G (Lowell Observatory), PA NNX10AB27G (MIT), and PA NNX12AJ29G (Williams College), as well as the National Research Foundation of

  19. Radio Occultation Measurements of Pluto's Atmosphere with New Horizons

    Science.gov (United States)

    Hinson, David P.; Linscott, Ivan; Young, Leslie; Stern, S. Alan; Bird, Mike; Ennico, Kimberly; Gladstone, Randy; Olkin, Catherine B.; Pätzold, Martin; Strobel, Darrell F.; Summers, Michael; Tyler, G. Leonard; Weaver, Harold A.; Woods, Will; New Horizons Science Team

    2016-10-01

    The reconnaissance of the Pluto System by New Horizons in July 2015 included a radio occultation at Pluto. The observation was performed with signals transmitted simultaneously by four antennas of the NASA Deep Space Network, two at the Goldstone complex in California and two at the Canberra complex in Australia. Each antenna radiated 20 kW without modulation at a wavelength of 4.17 cm. New Horizons received the four signals with its 2.1-m high-gain antenna, where the signals were split into pairs and processed independently by two identical REX radio science instruments. Each REX relied on a different ultra-stable oscillator as its frequency reference. The signals were digitized and filtered, and the data samples were stored on the spacecraft for later transmission to Earth. Six months elapsed before all data had arrived on the ground, and the results reported here are the first to utilize the complete set of observations. Pluto's tenuous atmosphere is a significant challenge for radio occultation sounding, which led us to develop a specialized method of analysis. We began by calibrating each signal to remove effects not associated with Pluto's atmosphere, including the diffraction pattern from Pluto's surface. We reduced the noise and increased our sensitivity to the atmosphere by averaging the results from the four signals, while using other combinations of the signals to characterize the noise. We then retrieved profiles of number density, pressure, and temperature from the averaged phase profiles at both occultation entry and exit. Finally, we used a combination of analytical methods and Monte Carlo simulations to determine the accuracy of the measurements. The REX profiles provide the first direct measure of the surface pressure and temperature structure in Pluto's lower atmosphere. There are significant differences between the structure at entry (193.5°E, 17.0°S, sunset) and exit (15.7°E, 15.1°N, sunrise), which arise from spatial variations in surface

  20. Occult hepatitis C virus infection is more common than hepatitis B infection in maintenance hemodialysis patients

    OpenAIRE

    Jain, Pankaj; Nijhawan, Sandeep

    2008-01-01

    Patients of end stage renal disease on maintenance hemodialysis were enrolled to study the prevalence of occult and dual hepatitis B virus (HBV) and hepatitis C virus (HCV) infection and non-occult hepatitis B and C virus infection. One hundred and two patients were enrolled. Thirty patients had HCV infection, three of them were positive in anti-HCV. So, 27 (90%) of HCV-positive patients had occult HCV infection. Eleven (11%) patients had HBV infection. Five patients were positive in anti-HBc...

  1. First light of an external occulter testbed at flight Fresnel numbers

    Science.gov (United States)

    Kim, Yunjong; Sirbu, Dan; Hu, Mia; Kasdin, Jeremy; Vanderbei, Robert J.; Harness, Anthony; Shaklan, Stuart

    2017-01-01

    Many approaches have been suggested over the last couple of decades for imaging Earth-like planets. One of the main candidates for creating high-contrast for future Earth-like planets detection is an external occulter. The external occulter is a spacecraft flown along the line-of-sight of a space telescope to suppress starlight and enable high-contrast direct imaging of exoplanets. The occulter is typically tens of meters in diameter and the separation from the telescope is of the order of tens of thousands of kilometers. Optical testing of a full-scale external occulter on the ground is impossible because of the long separations. Therefore, laboratory verification of occulter designs is necessary to validate the optical models used to design and predict occulter performance. At Princeton, we have designed and built a testbed that allows verification of scaled occulter designs whose suppressed shadow is mathematically identical to that of space occulters. The goal of this experiment is to demonstrate a pupil plane suppression of better than 1e-9 with a corresponding image plane contrast of better than 1e-11. The occulter testbed uses a 77.2 m optical propagation distance to realize the flight Fresnel number of 14.5. The scaled mask is placed at 27.2 m from the artificial source and the camera is located 50.0 m from the scaled mask. We will use an etched silicon mask, manufactured by the Microdevices Lab(MDL) of the Jet Propulsion Laboratory(JPL), as the occulter. Based on conversations with MDL, we expect that 0.5 μm feature size is an achievable resolution in the mask manufacturing process and is therefore likely the indicator of the best possible performance. The occulter is illuminated by a diverging laser beam to reduce the aberrations from the optics before the occulter. Here, we present first light result of a sample design operating at a flight Fresnel number and the experimental setup of the testbed. We compare the experimental results with simulations

  2. Do X-ray-occult fractures play a role in chronic pain following a whiplash injury?

    DEFF Research Database (Denmark)

    Hertzum-Larsen, Rasmus; Petersen, Henrik; Kasch, Helge

    2014-01-01

    symptoms following an MVA was invited to have a cervical SPECT shortly post injury and again 6 months later. Associations between occult fractures and pain levels at baseline, 6 and 12 months of follow-up were analyzed. Eighty-eight patients had baseline SPECT performed at median 15 days (range 3-28) post...... injury, but only 49 patients accepted to have the follow-up SPECT at 6 months. Abnormal SPECT, defined as minimum one area of focal uptake, was seen in 32 patients at baseline, reflecting an occult fracture. Occult fractures were not associated with pain levels, neither at baseline nor at follow...

  3. Occult Orbitocranial Penetrating Pencil Injury in a Child

    Directory of Open Access Journals (Sweden)

    Faisal Al-Otaibi

    2012-01-01

    Full Text Available Transorbital slow-penetrating injury is an uncommon type of head injury that is seen more often in the pediatric age group. This type of injury can be occult, which is often associated with serious complications. We report on a 4-year-old female who presented with orbital swelling after an unwitnessed right orbital injury following a fall on her face at her school. Three days after injury, the presence of a foreign body was discovered on imaging study when she presented with orbital swelling and purulent discharges. She recovered well after surgical and medical management. This paper sheds light on the importance of high suspicion for the presence and early surgical management of a penetrating foreign body.

  4. Atmospheric stability index using radio occultation refractivity profiles

    Indian Academy of Sciences (India)

    D Jagadheesha; B Manikiam; Neerja Sharma; P K Pal

    2011-04-01

    A new stability index based on atmospheric refractivity at ∼500 hPa level and surface measurements of temperature, pressure and humidity is formulated. The new index named here as refractivity based lifted index (RLI) is designed to give similar results as traditionally used lifted index derived from radiosonde profiles of temperature, pressure and humidity. The formulation of the stability index and its comparison with the traditional temperature profile based lifted index (LI) is discussed. The index is tested on COSMIC radio occultation derived refractivity profiles over Indian region. The forecast potential of the new index for rainfall on 2° × 2° latitude–longitude spatial scale with lead time of 3–24 hours indicate that the refractivity based lifted index works better than the traditional temperature based lifted index for the Indian monsoon region. Decreasing values of RLI tend to give increasing rainfall probabilities.

  5. Radiographically Occult and Subtle Fractures: A Pictorial Review

    Directory of Open Access Journals (Sweden)

    Mohamed Jarraya

    2013-01-01

    Full Text Available Radiographically occult and subtle fractures are a diagnostic challenge. They may be divided into (1 “high energy trauma fracture,” (2 “fatigue fracture” from cyclical and sustained mechanical stress, and (3 “insufficiency fracture” occurring in weakened bone (e.g., in osteoporosis and postradiotherapy. Independently of the cause, the initial radiographic examination can be negative either because the findings seem normal or are too subtle. Early detection of these fractures is crucial to explain the patient’s symptoms and prevent further complications. Advanced imaging tools such as computed tomography, magnetic resonance imaging, and scintigraphy are highly valuable in this context. Our aim is to raise the awareness of radiologists and clinicians in these cases by presenting illustrative cases and a discussion of the relevant literature.

  6. Clinicopathologic correlations and significance of clinically occult mammary lesions.

    Science.gov (United States)

    Schwartz, G F; Feig, S A; Patchefsky, A S

    1978-03-01

    Experience with 189 clinically occult, i.e., nonpalpable breast lesions is presented. The described technique of localization and excision all but guarantees removal of even the smallest radiographically suspicious findings with an inconspicuous incision and minimal breast deformity. The incidence of carcinoma encountered in these 189 biopsies is 27.5%. Axillary node metastases were present in less than 25% of the invasive nonpalpable cancers, approximately half of what might have been expected if the lesions had been discovered in the usual manner. There were no patients with axillary node metastases among those with in situ ductal or microinvasive ductal carcinomas. This implies a better prognosis and lower death rate from breast cancer in these patients. Screening programs employing mammography, designed to detect breast cancers in this pre-palpable stage, are encountered as a means of uncovering a higher proportion of such cancers at an earlier stage in their natural histories.

  7. HITRAN spectroscopy evaluation using solar occultation FTIR spectra

    Science.gov (United States)

    Toon, Geoffrey C.; Blavier, Jean-Francois; Sung, Keeyoon; Rothman, Laurence S.; E. Gordon, Iouli

    2016-10-01

    High resolution FTIR solar occultation spectra, acquired by the JPL MkIV Fourier transform spectrometer from balloon, covering 650-5650 cm-1 at 0.01 cm-1 resolution, are systematically analyzed using the last four versions of the HITRAN linelist (2000, 2004, 2008, 2012). The rms spectral fitting residuals are used to assess the quality and adequacy of the linelists as a function of wavenumber and altitude. Although there have been substantial overall improvements with each successive version of HITRAN, there are nevertheless a few spectral regions where the latest HITRAN version (2012) has regressed, or produces residuals that far exceed the noise level. A few of these instances are investigated further and their causes identified. We emphasize that fitting atmospheric spectra, in addition to laboratory spectra, should be part of the quality assurance for any new linelist before public release.

  8. Adolescent Occultism and the Philosophy of Things in Three Novels

    Directory of Open Access Journals (Sweden)

    Samuel Finegan

    2015-11-01

    Full Text Available Shirley Jackson’s 1962 We Have Always Lived in the Castle, Iain Banks’s 1984 The Wasp Factory and Sonya Hartnett’s 2009 Butterfly are novels separated not only by decades, but by distance being produced in the United States, Scotland and Australia respectively. Despite this, each of these texts depicts a young adult in a mimetically recognisable world struggling to reconcile their intuitive occultism with that world. The mediation of magic through assemblages of charged objects creates a philosophy of things – modelling in intuitive and narrative terms the essence and nature of objects familiar from the philosophies of Martin Heidegger and Walter Benjamin. As such, the supernaturalism of Iain Banks, Shirley Jackson and Sonya Hartnett’s narratives implicates their readers – breaking the boundaries of fiction to comment on the material world itself, not through analogy or metaphor but through direct modelling of the potential power and worth of things.

  9. Radio occultation measurements of Pluto's neutral atmosphere with New Horizons

    Science.gov (United States)

    Hinson, D. P.; Linscott, I. R.; Young, L. A.; Tyler, G. L.; Stern, S. A.; Beyer, R. A.; Bird, M. K.; Ennico, K.; Gladstone, G. R.; Olkin, C. B.; Pätzold, M.; Schenk, P. M.; Strobel, D. F.; Summers, M. E.; Weaver, H. A.; Woods, W. W.

    2017-07-01

    On 14 July 2015 New Horizons performed a radio occultation (RO) that sounded Pluto's atmosphere down to the surface. The sensitivity of the measurements was enhanced by a unique configuration of ground equipment and spacecraft instrumentation. Signals were transmitted simultaneously by four antennas of the NASA Deep Space Network, each radiating 20 kW at a wavelength of 4.2 cm. The polarization was right circular for one pair of signals and left circular for the other pair. New Horizons received the four signals and separated them by polarization for processing by two independent receivers, each referenced to a different ultra-stable oscillator. The two data streams were digitized, filtered, and stored on the spacecraft for later transmission to Earth. The results reported here are the first to utilize the complete set of observations. We calibrated each signal to remove effects not associated with Pluto's atmosphere, including the limb diffraction pattern. We then applied a specialized method of analysis to retrieve profiles of number density, pressure, and temperature from the combined phase measurements. Occultation entry sounded the atmosphere at sunset at 193.5°E, 17.0°S - on the southeast margin of an ice-filled basin known informally as Sputnik Planitia (SP); occultation exit occurred at sunrise at 15.7°E, 15.1°N - near the center of the Charon-facing hemisphere. Above 1215 km radius (∼25 km altitude) there is no discernible difference between the measurements at entry and exit, and the RO profiles are consistent with results derived from ground-based stellar occultation measurements. At lower altitudes the RO measurements reveal horizontal variations in atmospheric structure that had not been observed previously, and they are the first to reach the ground. The entry profile has a strong temperature inversion that ends 3.5 km above the surface, and the temperature in the cold boundary layer beneath the inversion is nearly constant, 38.9 ± 2.1 K, and

  10. Clinical significance of occult hepatitis B virus infection

    Institute of Scientific and Technical Information of China (English)

    Miriam Romero; Antonio Madejón; Conrado Fernández-Rodríguez; Javier García-Samaniego

    2011-01-01

    Occult hepatitis B virus (HBV) infection (OBI) is defined as the presence of HBV DNA in the liver (with or without detectable HBV DNA in serum) for individuals testing HBV surface antigen negative. Until recently, the clinical effect of OBI was unclear on the progression of liver disease; on the development of hepatocellular carcinoma; and on the risk for reactivation or transmission of HBV infection. Several studies suggest a high prevalence of OBI among patients with cryptogenic chronic liver disease, but its role in the progression to cirrhosis remains unclear. Although OBI has been well documented in human immunodeficiency virus (HIV)-positive patients, especially among those coinfected with hepatitis C virus, further studies are needed to determine its current clinical impact in HIV setting.

  11. Quasi-periodic pulsations in partially occulted flares

    Science.gov (United States)

    Szaforz, Zaneta; Tomczak, Michal

    The model of oscillating magnetic traps (OMT) suggests that the cusp-like magnetic structures located in an upper part of flare loops are responsible for quasi-periodic pulsations (QPP) observed sometimes in hard X-rays (HXR). Electrons within these oscillating traps are efficiently accelerated and confined, therefore the traps should be recognize as loop-top HXR sources. However, these sources are difficult for reconstruction in the presence of the stronger footpoint HXR sources. To overcome this problem, we analyzed partially occulted flares, observed by Yohkoh, from the survey of Tomczak (2009). We will present the correlation between the diameter of the loop-top HXR source and the period of pulsations. We will present also some interesting examples of observations, for which changes in QPPs coincide with the changes in appearance of loop-top sources.

  12. Remote sensing of tropospheric turbulence using GPS radio occultation

    Science.gov (United States)

    Shume, Esayas; Ao, Chi

    2016-07-01

    Radio occultation (RO) measurements are sensitive to the small-scale irregularities in the atmosphere. In this study, we present a new technique to estimate tropospheric turbulence strength (namely, scintillation index) by analyzing RO amplitude fluctuations in impact parameter domain. GPS RO observations from the COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) satellites enabled us to calculate global maps of scintillation measures, revealing the seasonal, latitudinal, and longitudinal characteristics of the turbulent troposphere. Such information are both difficult and expensive to obtain especially over the oceans. To verify our approach, simulation experiments using the multiple phase screen (MPS) method were conducted. The results show that scintillation indices inferred from the MPS simulations are in good agreement with scintillation measures estimated from COSMIC observations.

  13. Occult Celiac Disease Associated with Lymphocytic Sclerosing Cholangitis

    Directory of Open Access Journals (Sweden)

    Hugh J Freeman

    1994-01-01

    Full Text Available A 60-year-old male with dermatitis herpetiformis and a previously treated lymphoma involving an inguinal lymph node developed abnormal liver chemistry tests. Because of intermittent diarrhea, additional studies revealed lymphocytic colitis and occult celiac disease that responded to a gluten-free diet. A liver biopsy done to explore persistently abnormal liver chemistry tests showed a portal tract-centred inflammatory process characterized by biliary ductal proliferation, epithelial lymphocytosis and concentric lamellar fibrosis. Quantitation of immunoglobulins was normal and antimitochondrial antibodies were negative. Retrograde cholangiograms showed radiological features typical of primary sclerosing cholangius. The epithelial lymphocycosis reported in gastric, small and large intestinal mucosa of some patients with celiac disease may also be present in the biliary ductal columnar epithelium. This report provides additional evidence that celiac disease may be a far more extensive pathological process.

  14. Remote Sensing of Tropospheric Turbulence Using GPS Radio Occultation

    Science.gov (United States)

    Shume, E. B.; Ao, C. O.

    2015-12-01

    The purposes of this abstract are twofold: (i) It presents estimates of tropospheric turbulence strength (namely, scintillation index) by analyzing radio occultation (RO) observations from the COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) satellites. The availability of global observation worth of several years of COSIMC RO profiles enabled us to calculate global maps of scintillation measures (such information are both difficult and expensive especially over the oceans) revealing the seasonal, latitudinal, and longitudinal characteristics of the turbulent troposphere in greater details, and (ii) the manuscript also presents the application of a multiple phase screen (MPS) model simulation to investigate and quantify the effects of tropospheric turbulence on L-band communication and navigation signals received in a GPS (Global Positioning System) to a LEO (Low Earth Orbiting) satellites radio links. The scintillation indices inferred from the MPS simulations are shown to be in a reasonable agreement with scintillation measures estimated from COSMIC RO observations.

  15. Exploring overstabilities in Saturn's A ring using two stellar occultations

    CERN Document Server

    Hedman, M M; Salo, H

    2014-01-01

    Certain regions of Saturn's rings exhibit periodic opacity variations with characteristic radial wavelengths of up to a few hundred meters that have been attributed to viscous overstabilities. The Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft observed two stellar occultations of the star gamma Crucis that had sufficient resolution to discern a sub-set of these periodic patterns in a portion of the A ring between 124,000 and 125,000 km from Saturn center. These data reveal that the wavelengths and intensities of the patterns vary systematically across this region, but that these parameters are not strictly determined by the ring's average optical depth. Furthermore, our observations indicate that these opacity variations have an azimuthal coherence scale of around 3000 km.

  16. The prototype cameras for trans-Neptunian automatic occultation survey

    Science.gov (United States)

    Wang, Shiang-Yu; Ling, Hung-Hsu; Hu, Yen-Sang; Geary, John C.; Chang, Yin-Chang; Chen, Hsin-Yo; Amato, Stephen M.; Huang, Pin-Jie; Pratlong, Jerome; Szentgyorgyi, Andrew; Lehner, Matthew; Norton, Timothy; Jorden, Paul

    2016-08-01

    The Transneptunian Automated Occultation Survey (TAOS II) is a three robotic telescope project to detect the stellar occultation events generated by TransNeptunian Objects (TNOs). TAOS II project aims to monitor about 10000 stars simultaneously at 20Hz to enable statistically significant event rate. The TAOS II camera is designed to cover the 1.7 degrees diameter field of view of the 1.3m telescope with 10 mosaic 4.5k×2k CMOS sensors. The new CMOS sensor (CIS 113) has a back illumination thinned structure and high sensitivity to provide similar performance to that of the back-illumination thinned CCDs. Due to the requirements of high performance and high speed, the development of the new CMOS sensor is still in progress. Before the science arrays are delivered, a prototype camera is developed to help on the commissioning of the robotic telescope system. The prototype camera uses the small format e2v CIS 107 device but with the same dewar and also the similar control electronics as the TAOS II science camera. The sensors, mounted on a single Invar plate, are cooled to the operation temperature of about 200K as the science array by a cryogenic cooler. The Invar plate is connected to the dewar body through a supporting ring with three G10 bipods. The control electronics consists of analog part and a Xilinx FPGA based digital circuit. One FPGA is needed to control and process the signal from a CMOS sensor for 20Hz region of interests (ROI) readout.

  17. Pluto's Atmosphere from the July 2010 Stellar Occultation

    Science.gov (United States)

    Person, Michael J.; Elliot, J. L.; Bosh, A. S.; Gulbis, A. A. S.; Jensen-Clem, R.; Lockhart, M. F.; Zangari, A. M.; Zuluaga, C. A.; Levine, S. E.; Pasachoff, J. M.; Souza, S. P.; Lu, M.; Malamut, C.; Rojo, P.; Bailyn, C. D.; MacDonald, R. K. D.; Ivarsen, K. M.; Reichart, D. E.; LaCluyze, A. P.; Nysewander, M. C.; Haislip, J. B.

    2010-10-01

    We have observed the 4 July 2010 stellar occultation by Pluto as part of our program of monitoring Pluto's atmospheric changes over the last decade. Successful observations were obtained from three sites: Cerro Calan and Cerro Tololo, Chile, as well as the HESS-project site (High Energy Stereoscopic System) in southwestern Namibia. Successful telescope apertures ranged from 0.45 m to 1.0 m and resulted in seven occultation light curves for the event from among the three sites. Simultaneous analysis of the seven light curves indicates that Pluto's atmosphere continues to be stable, as the calculated atmospheric radii are consistent with those detected in 2006 (Elliot et al., AJ 134, 1, 2007) and 2007 (Person et al., AJ 136, 1510, 2008), continuing the stability that followed the large pressure increase detected between 1988 (Millis et al., Icarus 105, 282, 1993) and 2002 (Elliot et al., Nature 424, 165, 2003). We will present the overall astrometric solution as well as current profiles for Pluto's upper atmospheric temperature and pressure obtained from inversion of the light curves (Elliot, Person, and Qu, AJ 126, 1041, 2003). This work was supported, in part, by grants NNX10AB27G to MIT, NNX08AO50G to Williams College, and NNH08AI17I to the USNO from NASA's Planetary Astronomy Division. The 0.75-m ATOM (Automatic Telescope for Optical Monitoring) light curve was obtained with the generous assistance of the HESS-project staff, arranged by Stefan Wagner and Marcus Hauser of the University of Heidelberg. The 0.45-m Goto telescope at Cerro Calán National Astronomical Observatory, Universidad de Chile, was donated by the Government of Japan. PROMPT (Panchromatic Robotic Optical Monitoring and Polarimetry Telescopes) observations at Cerro Tololo were made possible by the Robert Martin Ayers Science Fund. Student participation was supported in part by NSF's REU program and NASA's Massachusetts Space Grant.

  18. Cassini RSS occultation observations of density waves in Saturn's rings

    Science.gov (United States)

    McGhee, C. A.; French, R. G.; Marouf, E. A.; Rappaport, N. J.; Schinder, P. J.; Anabtawi, A.; Asmar, S.; Barbinis, E.; Fleischman, D.; Goltz, G.; Johnston, D.; Rochblatt, D.

    2005-08-01

    On May 3, 2005, the first of a series of eight nearly diametric occultations by Saturn's rings and atmosphere took place, observed by the Cassini Radio Science (RSS) team. Simultaneous high SNR measurements at the Deep Space Network (DSN) at S, X, and Ka bands (λ = 13, 3.6, and 0.9 cm) have provided a remarkably detailed look at the radial structure and particle scattering behavior of the rings. By virtue of the relatively large ring opening angle (B=-23.6o), the slant path optical depth of the rings was much lower than during the Voyager epoch (B=5.9o), making it possible to detect many density waves and other ring features in the Cassini RSS data that were lost in the noise in the Voyager RSS experiment. Ultimately, diffraction correction of the ring optical depth profiles will yield radial resolution as small as tens of meters for the highest SNR data. At Ka band, the Fresnel scale is only 1--1.5 km, and thus even without diffraction correction, the ring profiles show a stunning array of density waves. The A ring is replete with dozens of Pandora and Prometheus inner Lindblad resonance features, and the Janus 2:1 density wave in the B ring is revealed with exceptional clarity for the first time at radio wavelengths. Weaker waves are abundant as well, and multiple occultation chords sample a variety of wave phases. We estimate the surface mass density of the rings from linear density wave models of the weaker waves. For stronger waves, non-linear models are required, providing more accurate estimates of the wave dispersion relation, the ring surface mass density, and the angular momentum exchange between the rings and satellite. We thank the DSN staff for their superb support of these complex observations.

  19. Between occultism and drama. Henrik Ibsen and Aleister Crowley

    Directory of Open Access Journals (Sweden)

    Giuliano D' Amico

    2015-02-01

    Full Text Available The article investigates the references to the works of Henrik Ibsen that the writer and occultist Aleister Crowley scattered in his writings around the turn of the 20th century, in the early phase of his career as a writer and occultist. Crowley’s reading of Ibsen has a marked a socio-political bent, especially in his interpretation of the work of the Norwegian playwright as an act of rebellion against the bourgeois (and for Crowley, Victorian system of values. Also, such view is enriched by a spiritual and individualistic interpretation of Ibsen as an “Artist”, i.e., in the light of Crowley’s occult doctrine, Thelema, of an individual who has found his own “Will” and can inspire others to do so. Such social and spiritual interpretations of Ibsen on Crowley’s part found their literary realization in his one-act play The Mother’s Tragedy (1899. The article claims that Crowley’s reading of Ibsen can give some new insight in the mechanisms of reception of the Norwegian playwright, by opening up for a reading of some of his plays within an occult discourse. Also, it is an occasion to treat Crowley – a figure that was constantly present in the European cultural and literary life of the last decade of the 19th century and of the first five decades of the 20th – with a different attitude than the irony and disdain to which he is often exposed.

  20. Modeling the Interaction of Moist Convection with the Zonal Jets of Jupiter

    Science.gov (United States)

    Li, L.; Ingersoll, A. P.

    2004-11-01

    We use a reduced-gravity quasi-geostrophic model with a parameterization of moist convection that is based on Galileo and Cassini observations of lightning and convective storms (Little et al., 1999; Gierasch et al., 2000; Porco et al., 2003). The features of the jets we want to reproduce in the model include: (1) the curvature of the zonal jet profile, which violates the barotropic stability criterion near many of the westward jets (Ingersoll et al., 1981; Li et al., 2004), (2) the speed of the zonal jets, which is related to their width, given that the jets marginally violate the barotropic stability criterion, and (3) the sign of the eddy momentum flux, which is into the jets and tends to sustain them (Beebe et al., 1979; Ingersoll et al., 1981; Salyk et al., 2004). The features of moist convective storms that are taken from observation include: (1) the tendency of the storms to occur in the cyclonic belts, (2) the rapid divergence of horizontal velocity near the cloud tops, and (3) the lifetime of the storms, which is on average 4-5 days (Li et al., 2004). We find that moist convection leads to zonal jets in the upper layer, but the jets violate the barotropic stability criterion only if the flow in the deep underlying layer is westward. We can reproduce the chevron shape on the sides of the jets if we postulate that the clouds persist longer than the storms that produce them. We can reproduce the number and frequency of moist convection storms by assuming that they carry most of the planet's vertical heat flux (Gierasch et al., 2000). The NASA Planetary Atmospheres Program supported this research.

  1. The influence of the stratosphere on the tropospheric zonal wind response to CO2 doubling

    Directory of Open Access Journals (Sweden)

    C. J. Bell

    2011-05-01

    Full Text Available The influence of a CO2 doubling on the stratospheric potential vorticity (PV is examined in two climate models. Subsequently, the influence of changes in the stratosphere on the tropospheric zonal wind response is investigated, by inverting the stratospheric PV. Radiative effects seem to dominate the stratospheric response to CO2 doubling in the Southern Hemisphere. These lead to a stratospheric PV increase at the edge of the polar vortex, resulting in an increased westerly influence of the stratosphere on the troposphere, increasing the midlatitude tropospheric westerlies in late winter. In the Northern Hemisphere, dynamical effects are also important. Both models show a reduced polar PV and an enhanced midlatitude PV in the Northern Hemisphere winter stratosphere. These PV changes are likely related to an enhanced wave forcing of the winter stratosphere, as measured by an increase in the 100 hPa eddy heat flux, and result in a reduced westerly influence of the stratosphere on the high latitude tropospheric winds. In one model, the high latitude PV decreases are, however, restricted to higher altitudes, and the tropospheric response due to the stratospheric changes is dominated by an increased westerly influence in the midlatitudes, related to the increase in midlatitude PV in the lower stratosphere. The tropospheric response in zonal wind due to the stratospheric PV changes is of the order of 0.5 to 1 m s−1. The total tropospheric response has a somewhat different spatial structure, but is of similar magnitude. This indicates that the stratospheric influence is of importance in modifying the tropospheric zonal wind response to CO2 doubling.

  2. Instabilities of continuously stratified zonal equatorial jets in a periodic channel model

    Directory of Open Access Journals (Sweden)

    S. Masina

    Full Text Available Several numerical experiments are performed in a nonlinear, multi-level periodic channel model centered on the equator with different zonally uniform background flows which resemble the South Equatorial Current (SEC. Analysis of the simulations focuses on identifying stability criteria for a continuously stratified fluid near the equator. A 90 m deep frontal layer is required to destabilize a zonally uniform, 10° wide, westward surface jet that is symmetric about the equator and has a maximum velocity of 100 cm/s. In this case, the phase velocity of the excited unstable waves is very similar to the phase speed of the Tropical Instability Waves (TIWs observed in the eastern Pacific Ocean. The vertical scale of the baroclinic waves corresponds to the frontal layer depth and their phase speed increases as the vertical shear of the jet is doubled. When the westward surface parabolic jet is made asymmetric about the equator, in order to simulate more realistically the structure of the SEC in the eastern Pacific, two kinds of instability are generated. The oscillations that grow north of the equator have a baroclinic nature, while those generated on and very close to the equator have a barotropic nature. 

    This study shows that the potential for baroclinic instability in the equatorial region can be as large as at mid-latitudes, if the tendency of isotherms to have a smaller slope for a given zonal velocity, when the Coriolis parameter vanishes, is compensated for by the wind effect.

    Key words. Oceanography: general (equatorial oceanography; numerical modeling – Oceanography: physics (fronts and jets

  3. Reversal and amplification of zonal flows by boundary enforced thermal wind

    Science.gov (United States)

    Dietrich, W.; Gastine, T.; Wicht, J.

    2017-01-01

    Zonal flows in rapidly-rotating celestial objects such as the Sun, gas or ice giants form in a variety of surface patterns and amplitudes. Whereas the differential rotation on the Sun, Jupiter and Saturn features a super-rotating equatorial region, the ice giants, Neptune and Uranus harbour an equatorial jet slower than the planetary rotation. Global numerical models covering the optically thick, deep-reaching and rapidly rotating convective envelopes of gas giants reproduce successfully the prograde jet at the equator. In such models, convective columns shaped by the dominant Coriolis force typically exhibit a consistent prograde tilt. Hence angular momentum is pumped away from the rotation axis via Reynolds stresses. Those models are found to be strongly geostrophic, hence a modulation of the zonal flow structure along the axis of rotation, e.g. introduced by persistent latitudinal temperature gradients, seems of minor importance. Within our study we stimulate these thermal gradients and the resulting ageostrophic flows by applying an axisymmetric and equatorially symmetric outer boundary heat flux anomaly (Y20) with variable amplitude and sign. Such a forcing pattern mimics the thermal effect of intense solar or stellar irradiation. Our results suggest that the ageostrophic flows are linearly amplified with the forcing amplitude q⋆ leading to a more pronounced dimple of the equatorial jet (alike Jupiter). The geostrophic flow contributions, however, are suppressed for weak q⋆, but inverted and re-amplified once q⋆ exceeds a critical value. The inverse geostrophic differential rotation is consistently maintained by now also inversely tilted columns and reminiscent of zonal flow profiles observed for the ice giants. Analysis of the main force balance and parameter studies further foster these results.

  4. The influence of the stratosphere on the tropospheric zonal wind response to CO2 doubling

    Directory of Open Access Journals (Sweden)

    P. C. Siegmund

    2010-10-01

    Full Text Available The influence of a CO2 doubling on the stratospheric potential vorticity (PV is examined in two climate models. Subsequently, the influence of changes in the stratosphere on the tropospheric zonal wind response is investigated, by inverting the stratospheric PV. Radiative effects dominate the stratospheric response to CO2 doubling in the Southern Hemisphere. These lead to a stratospheric PV increase at the edge of the polar vortex, resulting in an increased westerly influence of the stratosphere on the tropospheric midlatitude winds in late winter. In the Northern Hemisphere, dynamical effects are also important. Both models show a reduced polar PV and an enhanced midlatitude PV in the Northern Hemisphere winter stratosphere. These PV changes are related to an enhanced wave forcing of the winter stratosphere, as measured by an increase in the 100 hPa eddy heat flux, and result in a reduced westerly influence of the stratosphere on the high latitude tropospheric winds. In one model, the high latitude PV decreases are, however, restricted to higher altitudes, and the tropospheric response due to the stratospheric changes is dominated by an increased westerly influence in the midlatitudes, related to the increase in midlatitude PV in the lower stratosphere. The tropospheric response in zonal wind due to the stratospheric PV changes is of the order of 0.5 to 1 m s−1. The total tropospheric response has a somewhat different spatial structure, but is of similar magnitude. This indicates that the stratospheric influence is of importance in modifying the tropospheric zonal wind response to CO2 doubling.

  5. The sensitivity of stationary waves to variations in the basic state zonal flow

    Science.gov (United States)

    Nigam, Sumant; Lindzen, Richard S.

    1989-01-01

    A linear, primitive equation stationary wave model having high vertical and meridional resolution is used to examine the sensitivity of orographically forced (primarily by Himalayas) stationary waves at middle and high latitudes to variations in the basic state zonal wind distribution. We find relatively little sensitivity to the winds in high latitudes, but remarkable sensitivity to small variations in the subtropical jet. Fluctuations well within the range of observed variability in the jet can lead to large variations in the stationary waves of the high latitude stratosphere, and to large changes even in tropospheric stationary waves. Implications for both sudden warmings and large-scale weather are discussed.

  6. Isotope effect on gyro-fluid edge turbulence and zonal flows

    CERN Document Server

    Meyer, Ole Hauke Heinz

    2016-01-01

    The role of ion polarisation and finite Larmor radius on the isotope effect on turbulent tokamak edge transport and flows is investigated by means of local electromagnetic multi-species gyro-fluid computations. Transport is found to be reduced with the effective plasma mass for protium, deuterium and tritium mixtures. This isotope effect is found for both cold and warm ion models, but significant influence of finite Larmor radius and polarisation effects are identified. Sheared flow reduction of transport through self generated turbulent zonal flows and geodesic acoustic modes in the present model (not including neoclassical flows) is found to play only a minor role on regulating isotopically improved confinement.

  7. Effects of energetic particles on zonal flow generation by toroidal Alfven eigenmode

    CERN Document Server

    Qiu, Zhiyong; Zonca, Fulvio

    2016-01-01

    Generation of zonal ow (ZF) by energetic particle (EP) driven toroidal Alfven eigenmode (TAE) is investigated using nonlinear gyrokinetic theory. It is found that, nonlinear resonant EP contri- bution dominates over the usual Reynolds and Maxwell stresses due to thermal plasma nonlinear response. ZF can be forced driven in the linear growth stage of TAE, with the growth rate being twice the TAE growth rate. The ZF generation mechanism is shown to be related to polarization induced by resonant EP nonlinearity. The generated ZF has both the usual meso-scale and micro- scale radial structures. Possible consequences of this forced driven ZF on the nonlinear dynamics of TAE are also discussed.

  8. From international to zonal trials: the origins of the Nuremberg medical trial.

    Science.gov (United States)

    Weindling, P

    2000-01-01

    This article examines how plans to have a second International Military Tribunal led to the Medical Trial at Nuremberg. While the British opposed a second international trial because of their distrust of the Soviets, they supported a plan for a series of special zonal trials to be conducted by the American authorities at Nuremberg. In December 1945 the British became aware of the extent of medical war crimes committed by the Germans. Their investigation led to an eventual handover to the Americans of a group of German doctors for trial at Nuremberg. At the same time the British and French Supported an International Scientific Commission for the Investigation of Medical War Crimes.

  9. LETTER TO THE EDITOR: Magnetic islands and spontaneous generation of zonal flows

    Science.gov (United States)

    Grasso, D.; Margheriti, L.; Porcelli, F.; Tebaldi, C.

    2006-09-01

    A study of saturated magnetic island equilibria on the basis of the resistive magneto-hydro-dynamic model is presented. A bifurcation in the sequence of equilibria is found as the ratio of the width of the current layer in the initial (non-reconnected) configuration over the island periodicity length reaches a critical threshold. Below this threshold, spontaneous generation of zonal flows occurs. This result is suggestive of a possible evolution of current sheets in magnetically confined plasmas and may be relevant to the understanding of the suppression of drift-wave turbulence and the formation of internal transport barriers in tokamak experiments.

  10. Zonal flow driven by energetic particle during magneto-hydro-dynamic burst in a toroidal plasma

    Science.gov (United States)

    Ohshima, S.; Fujisawa, A.; Shimizu, A.; Nakano, H.; Iguchi, H.; Yoshimura, Y.; Nagaoka, K.; Minami, T.; Isobe, M.; Nishimura, S.; Suzuki, C.; Akiyama, T.; Takahashi, C.; Takeuchi, M.; Ito, T.; Watari, T.; Kumazawa, R.; Itoh, S.-I.; Itoh, K.; Matsuoka, K.; Okamura, S.

    2007-11-01

    The internal structural measurements of electric field and density using twin heavy ion beam probes have been performed to elucidate the nonlinear evolution of the magneto-hydro-dynamic (MHD) bursty phenomenon driven by the interaction with high-energy particles in a toroidal plasma. The results have given the finest observation of the internal structure of plasma quantities, such as electric field, density and magnetic field distortion, which nonlinearly develop during the MHD phenomenon. In particular, the finding of a new kind of oscillating zonal flow driven by interaction between energetic particles and MHD modes should be emphasized for burning state plasmas.

  11. Purification and concentration of influenza inactivated viruses by continuous-flow zonal centrifugation.

    Science.gov (United States)

    Mistretta, A P; Crovari-Cuneo, P; Giacometti, G; Sacchi, G; Strozzi, F

    1975-01-01

    A mathod is described for the purification, on an industrial scale, of influenza viruses grown in allantoic cavity of embryonated eggs. The mehtod consists of combining continuous-flow centrifugation with zonal centrifugation in a sucrose (36.6 per cent-52.5 per cent w/v) density gradient. The sample flow rate is approximately 3.7 litres/h and the volumes treated vary between 3 and 33 litres of allantoic fluid. Both the recovery of the virus and the degree of concentration and purification result satisfactory.

  12. Final Scientific/Technical Report for "Nanite" for Better Well-Bore Integrity and Zonal Isolation

    Energy Technology Data Exchange (ETDEWEB)

    Veedu, Vinod [Oceanit Laboratories, Inc., Honolulu, HI (United States); Hadmack, Michael [Oceanit Laboratories, Inc., Honolulu, HI (United States); Pollock, Jacob [Oceanit Laboratories, Inc., Honolulu, HI (United States); Pernambuco-Wise, Paul [Oceanit Laboratories, Inc., Honolulu, HI (United States); Ah Yo, Derek [Oceanit Laboratories, Inc., Honolulu, HI (United States)

    2017-05-30

    Nanite™ is a cementitious material that contains a proprietary formulation of functionalized nanomaterial additive to transform conventional cement into a smart material responsive to pressure (or stress), temperature, and any intrinsic changes in composition. This project has identified optimal sensing modalities of smart well cement and demonstrated how real-time sensing of Nanite™ can improve long-term wellbore integrity and zonal isolation in shale gas and applicable oil and gas operations. Oceanit has explored Nanite’s electrical sensing properties in depth and has advanced the technology from laboratory proof-of-concept to sub-scale testing in preparation for field trials.

  13. First simultaneous measurements of thermospheric winds and zonal ion drifts from the Jicamarca Radio Observatory

    Science.gov (United States)

    Meriwether, John; Baker, Brooke; Twork, Greg; Chau, Jorge; Veliz, Oskar; Woodman, Ronald; Hedden, Russell; Hysell, David

    The first simultaneous observations of thermospheric winds and zonal ion drifts have been ob-tained at the Jicamarca Radio Observatory using a new Fabry-Perot interferometer observatory installed on a mountain ridge overlooking the valley where the JRO radar is located. The re-sults show that the neutral winds and ion drifts generally have the same speed and temporal variation characteristics. These results illustrate the simultaneous detection of the midnight temperature maximum as well. The paper will also describe efforts to obtain common volume measurements of thermospheric winds and temperatures utilizing the FPI Arequipa observatory which is located 4 degrees south of the geomagnetic equator.

  14. Observations of Hot-Jupiter occultations combining Spitzer and Kepler photometry

    Directory of Open Access Journals (Sweden)

    Knutson H.

    2011-02-01

    Full Text Available We present the status of an ongoing program which aim at measuring occultations by their parent stars of transiting hot giant exoplanets discovered recently by Kepler. The observations are obtained in the near infrared with WarmSpitzer Space Telescope and at optical wavelengths by combining more than a year of Kepler photometry. The investigation consists of measuring the mid-occultation times and the relative occultation depths in each band-passes. Our measurements of occultations depths in the Kepler bandpass is turned into the determination of the optical geometric albedo Ag in this wavelength domain. The brightness temperatures of these planets are deduced from the infrared observations. We combine the optical and near infrared planetary emergent fluxes to obtain broad band emergent spectra of individual planet. We finally compare these spectra to hot Jupiter atmospheric models in order broadly distinguishing these atmospheres between different classes of models.

  15. Successful management of occult pneumothorax without tube thoracostomy despite positive pressure ventilation.

    Science.gov (United States)

    Barrios, Cristobal; Tran, Tuan; Malinoski, Darren; Lekawa, Michael; Dolich, Matthew; Lush, Stephanie; Hoyt, David; Cinat, Marianne E

    2008-10-01

    The objective of this study was to determine whether tube thoracostomy can be safely avoided in a subset of patients with blunt occult pneumothorax. A retrospective review was performed. Management without tube thoracostomy was attempted for 59 occult pneumothoraces and was successful in 51 (86%). Observation was successful in 16 of 20 occult pneumothoraces (80%) exposed to positive pressure ventilation within 72 hours of admission. Eight delayed tube thoracostomies were required an average of 19.7 hours post admission. Patients who failed observant management had more significant physiologic derangement on admission (revised trauma score 6.96 vs 7.66, P = 0.04), were more likely to have significant multisystem trauma (88% vs 37%, P = 0.007), but were not more likely to require positive pressure ventilation (PPV) (50% vs 31%, P = 0.31). This study demonstrates that a subset of patients with blunt occult pneumothorax requiring positive pressure ventilation may be safely managed without tube thoracostomy.

  16. Occult gastrointestinal bleeding due to a Dieulafoy lesion in the terminal ileum

    NARCIS (Netherlands)

    Wegdam, J.A.; Hofker, H.S.; Dijkstra, G; Stolk, M.F.; Jacobs, M.A.; Suurmeijer, A.J.H.

    2006-01-01

    A 50-year-old man awaiting liver transplantation for primary sclerosing cholangitis developed iron-deficiency anaemia. Repeated occult gastrointestinal bleeding led to an increasing need for blood transfusions. After multiple oesophagogastroduodenoscopies and colonoscopies, videocapsule endoscopy fi

  17. Search for serendipitous TNO occultation events in X-rays with Athena

    Science.gov (United States)

    Chang, Hsiang-Kuang; Liu, Chih-Yuan; Shang, Jie-Rou

    2015-09-01

    Trans-Neptunian Objects (TNOs), which include Kuiper Belt Objects (KBOs) and yet-to-discover Oort Cloud Objects, are an important population of members of the solar system. Its population properties, such as size distribution, carry information imprinted during the early epoch of the solar system formation. TNOs smaller than about ten kilometers are not directly observable. Their existence, however, may be detected through occultation events of background targets that they cause. Search for such serendipitous occultation events have been conducted in optical and X-ray bands. Since the Fresnel scale is about 30 times smaller in X-rays, using X-ray occultation events one may explore TNOs smaller than that can be done in optical bands. Here I will report X-ray sources suitable for such a study with Athena observations. The estimated Athena detection rate of occultation events, based on different model assumptions of TNO size distribution, will also be presented.

  18. Fabrication and Measurement of Precision Structures for External Occulter Optical Edges Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project proposes to develop an occulter optical edge and optical edge measurement verification system suitable for astrophysics missions including JWST and the...

  19. Occult hepatitis C virus infection is more common than hepatitis B infection in maintenance hemodialysis patients

    Institute of Scientific and Technical Information of China (English)

    Pankaj Jain; Sandeep Nijhawan

    2008-01-01

    Patients of end stage renal disease on maintenance hemodialysis were enrolled to study the prevalence of occult and dual hepatitis B virus (HBV) and hepatitis C virus (HCV) infection and non-occult hepatitis B and C virus infection. One hundred and two patients were enrolled. Thirty patients had HCV infection, three of them were positive in anti-HCV. So, 27 (90%) of HCVpositive patients had occult HCV infection. Eleven (11%)patients had HBV infection. Five patients were positive in anti-HBc or HBV-DNA, but negative in HBsAg (occult HBV infection). Three (3%) patients had dual HBV and HCV infection. None of the patients showed changes in viral markers during the follow-up of 8 mo on average (1-12 mo).

  20. Atmospheric Climate Change Detection Based on the GPS Radio Occultation Record

    Science.gov (United States)

    Steiner, A. K.; Lackner, B. C.; Hegerl, G. C.; Pirscher, B.; Borsche, M.; Foelsche, U.; Kirchengast, G.

    2009-04-01

    Monitoring of global climate change requires high quality observations of the Earth's atmosphere. Radio occultation (RO) measurements based on signals from Global Positioning System (GPS) satellites provide a useful upper air record in this respect. RO data are considered a climate benchmark data type since they are based on timing with precise atomic clocks and tied to the international definition of the second. High quality and vertical resolution in the upper troposphere and lower stratosphere (UTLS), long-term stability, and consistency of RO data stemming from satellites in different orbits without need for inter-calibration make RO well suited for atmospheric observations and climate change detection. RO data are available on a continuous basis since fall of 2001 from the German research satellite CHAMP (CHAllenging Minisatellite Payload for geoscientific research), establishing the first RO climate record covering more than seven years. Intermittent periods of observations from the U.S. GPS/Met proof-of-concept mission exist in the years 1995-1997, with sufficient data only for October 1995 and February 1997. We present a climate change detection study based on monthly mean zonal mean RO climatologies in the UTLS region within 9-25 km (300-30 hPa) where we use different detection methods. An optimal fingerprinting technique is applied to the whole record of RO accessible parameters refractivity, geopotential height, and temperature to detect a forced climate signal. Three representative global climate models of the 4th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) are employed to estimate natural climate variability by making use of pre-industrial control runs. The response pattern to the external forcings is presented by an ensemble mean of the models' A2 and B1 scenario runs. Optimal fingerprinting shows that a climate change signal can be detected at the 90% significance level in the RO refractivity record. Furthermore, simple

  1. Occult male breast cancer with axillary metastasis: A rare case report

    Directory of Open Access Journals (Sweden)

    Komal Sawaimul

    2015-01-01

    Full Text Available Breast cancer is very rare in men. It accounts for 0.2% of all cancers and 1% of all breast cancers. The occurrence of occult breast cancer that present as axillary metastasis as the first manifestation is even rarer in men. We are hereby presenting an extremely rare case of a septuagenarian male patient who presented with occult breast cancer and axillary lymph node metastasis.

  2. Occult Hepatitis B Virus Infection in a Previously Vaccinated Injection Drug User

    Directory of Open Access Journals (Sweden)

    Powell

    2016-02-01

    Full Text Available Introduction Occult hepatitis B virus (HBV is defined by the presence of HBV DNA in patient sera in the absence of HBsAg. Occult HBV has been associated with hepatocellular carcinoma, reactivation during immune suppression, and transmission to others. While the hepatitis B vaccine is very effective at preventing chronic HBV infection, recent studies indicate it is less effective at preventing occult HBV following infant vaccination. No studies, however, have examined the efficacy of adult HBV vaccination at preventing occult HBV. Here, we present the first report of occult HBV following adult vaccination. Case Presentation A 21-year old Caucasian female presented with tricuspid valve endocarditis secondary to methicillin-susceptible Staphylococcus aureus with non-ischemic cardiomyopathy. She reported active use of intravenous drugs. Her liver enzymes were elevated (ALT = 1873 IU/mL; AST = 4518 IU/mL, and she was found to have HCV and occult HBV. HBV viral loads ranged from 4608 - 8364 copies IU/mL during hospitalization. The patient’s HBV was sequenced and found to be genotype D3 without any known diagnostic escape mutations. Immune complexes that may have prevented HBsAg detection were not observed. Conclusions HBV vaccination in infancy is effective at preventing chronic HBV infection but is less effective at preventing occult HBV infection. Similar studies examining the efficacy of adult HBV vaccination in preventing occult HBV have not been performed. This case highlights the importance of carefully determining the HBV status of high-risk individuals, as vaccination history and the presence of anti-HBs may not be adequate to rule out HBV infection, even in the absence of HBsAg.

  3. Detection of occult hepatitis B virus among chronic hepatitis C patients

    Directory of Open Access Journals (Sweden)

    Ola Abd El Kader Mahmoud

    2016-06-01

    Results: Fifty-eight percent of the study group were positive for anti-HBc. Meanwhile, only 18 cases (18% were positive for the polymerase gene by nested PCR and were considered as occult HBV. Among these 18 polymerase gene positive patients (occult HBV anti-HBc was detected among 9 (50% of cases. Different gene profiles were noticed among the 18 polymerase gene positive patients.

  4. Seroprevalence of occult hepatitis B among Egyptian paediatric hepatitis C cancer patients.

    Science.gov (United States)

    Raouf, H E; Yassin, A S; Megahed, S A; Ashour, M S; Mansour, T M

    2015-02-01

    Occult hepatitis B infection is characterized by the presence of hepatitis B virus (HBV) DNA in the serum in the absence of hepatitis B surface antigen (HBsAg). Prevalence of hepatitis C virus (HCV) infections in Egypt is among the highest in the world. In this study, we aim at analysing the rates of occult HBV infections among HCV paediatric cancer patients in Egypt. The prevalence of occult HBV was assessed in two groups of paediatric cancer patients (HCV positive and HCV negative), in addition to a third group of paediatric noncancer patients, which was used as a general control. All groups were negative for HBsAg and positive for HCV antibody. HBV DNA was detected by nested PCR and real-time PCR. HCV was detected by real-time PCR. Sequencing was carried out in order to determine HBV genotypes to all HBV patients as well as to detect any mutation that might be responsible for the occult phenotype. Occult hepatitis B infection was observed in neither the non-HCV paediatric cancer patients nor the paediatric noncancer patients but was found in 31% of the HCV-positive paediatric cancer patients. All the detected HBV patients belonged to HBV genotype D, and mutations were found in the surface genome of HBV leading to occult HBV. Occult HBV infection seems to be relatively frequent in HCV-positive paediatric cancer patients, indicating that HBsAg negativity is not sufficient to completely exclude HBV infection. These findings emphasize the importance of considering occult HBV infection in HCV-positive paediatric cancer patients especially in endemic areas as Egypt.

  5. Cytokine profiles and hepatic injury in occult hepatitis C versus chronic hepatitis C virus infection.

    Science.gov (United States)

    Mousa, N; Eldars, W; Eldegla, H; Fouda, O; Gad, Y; Abousamra, N; Elmasry, E; Arafa, M

    2014-01-01

    Occult hepatitis C virus (HCV) infection is a new entity that should be considered when diagnosing patients with abnormal liver functions of unknown origin. This work was carried out to evaluate T-helper 1/T-helper 2 (Th1/Th2) cytokine profiles in patients with occult HCV infection versus chronic hepatitis C (CHC) infection, also to investigate any association between theses cytokines and liver histological features in both groups. Serum levels of Th1 cytokines (IL-2, IFN-gamma) and Th2 (IL-4 and IL-10) were measured in 35 patients with occult HCV infection compared to 50 patients with chronic hepatitis C infection and 30 healthy controls. We have found that Th1 cytokines were significantly increased in patients with CHC infection than in both occult HCV infection and control groups (p less than 0.001). On the other hand, serum IL-4 levels were higher in occult HCV infection than in CHC and control groups (p less than 0.001). Furthermore, serum IL-10 levels were higher in both patient groups vs control group (pless than 0.001), with no significant difference between CHC and occult HCV groups. Finally, only serum IL-10 levels were significantly higher among patients with high activity (A2-A3) than those with low activity (A0-A1) in both CHC and occult HCV groups (p=0.038, p=0.025, respectively). Patients with occult HCV infection exhibited a distinct immunoregulatory cytokine pattern that is shifted towards the Th2 arm.

  6. Frank hematuria as the presentation feature of acute leukemia

    Directory of Open Access Journals (Sweden)

    Suriya Owais

    2010-01-01

    Full Text Available Muco-cutaneous bleeding is a common presenting feature of acute leukemias. Mucosal bleeding usually manifests as gum bleeding and/or epistaxis but may occur in any mucosal surface of the body. Hematuria as an isolated or main presenting feature of acute leukemia is rare. We describe two cases of acute leukemia, a 19 year old male with acute lymphoblastic leukemia and a 52 year old male with acute myeloid leukemia, both presenting with gross hematuria. There was no demonstrable leukemic infiltration of the urinary tract on imaging studies. Hematuria in these patients was likely to be due to occult leukemic infiltration of the urinary system, aggravated by thrombocytopenia, as it subsided after starting chemotherapy. Our cases highlight that hematuria should be remembered as a rare presenting feature of acute leukemia.

  7. On the gravitational signature of zonal flows in Jupiter-like planets: An analytical solution and its numerical validation

    Science.gov (United States)

    Kong, Dali; Zhang, Keke; Schubert, Gerald

    2017-02-01

    It is expected that the Juno spacecraft will provide an accurate spectrum of the Jovian zonal gravitational coefficients that would be affected by both the deep zonal flow, if it exists, and the basic rotational distortion. We derive the first analytical solution, under the spheroidal-shape approximation, for the density anomaly induced by an internal zonal flow in rapidly rotating Jupiter-like planets. We compare the density anomaly of the analytical solution to that obtained from a fully numerical solution based on a three-dimensional finite element method; the two show excellent agreement. We apply the analytical solution to a rapidly rotating Jupiter-like planet and show that there exists a close relationship between the spatial structure of the zonal flow and the spectrum of zonal gravitational coefficients. We check the accuracy of the spheroidal-shape approximation by computing both the spheroidal and non-spheroidal solutions with exactly the same physical parameters. We also discuss implications of the new analytical solution for interpreting the future high-precision gravitational measurements of the Juno spacecraft.

  8. Storm time equatorial plasma bubble zonal drift reversal due to disturbance Hall electric field over the Brazilian region

    Science.gov (United States)

    Santos, A. M.; Abdu, M. A.; Souza, J. R.; Sobral, J. H. A.; Batista, I. S.; Denardini, C. M.

    2016-06-01

    The dynamics of equatorial ionospheric plasma bubbles over Brazilian sector during two magnetic storm events are investigated in this work. The observations were made at varying phases of magnetic disturbances when the bubble zonal drift velocity was found to reverse westward from its normally eastward velocity. Calculation of the zonal drift based on a realistic low-latitude ionosphere modeled by the Sheffield University Plasmasphere-Ionosphere Model showed on a quantitative basis a clear competition between vertical Hall electric field and disturbance zonal winds on the variations observed in the zonal velocity of the plasma bubble. The Hall electric field arising from enhanced ratio of field line-integrated conductivities, ΣH/ΣP, is most often generated by an increase in the integrated Hall conductivity, arising from enhanced energetic particle precipitation in the South American Magnetic Anomaly region for which evidence is provided from observation of anomalous sporadic E layers over Cachoeira Paulista and Fortaleza. Such sporadic E layers are also by themselves evidence for the development of the Hall electric field that modifies the zonal drift.

  9. Effects of zonal perturbations of sea surface temperature on tropical equilibrium states: A cloud-resolving modeling study

    Institute of Scientific and Technical Information of China (English)

    Xiaopeng Cui; Shouting Gao

    2008-01-01

    The effects of zonal perturbations of sea surface temperature (SST) on tropical equilibrium states are investigated based on a series of two-dimensional cloud-resolving simulations with imposed zero vertical velocity, constant zonal wind, and a zonal model domain of 768 km. Four experiments with zonal SST perturbations of wavenumbers 1 (Cl), 2 (C2), 4 (C3), and 8 (C4) are compared to a control experiment with zonally uniform SST (CO). The 40-day integrations show that the temperatures reach quasi-equilibrium states with distinct differences. Cl and C2 produce warmer equilibrium states whereas C3 and C4 generate colder equilibrium states than CO does. The heat budgets in the five experiments are analyzed. Compared to CO, less IR cooling over smaller clear-sky regions in Cl and more condensational heating in C2 are responsible for wanner equilibrium states. A reduced condensational heating leads to the cold equilibrium state in C3. The interaction between convective systems in C4 causes a decrease of condensational heating, which accounts for the cold equilibrium state.

  10. Dynamics of eddy-driven North Atlantic Oscillations in a localized shifting jet: zonal structure and downstream blocking

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Dehai [Ocean University of China, College of Physical and Environmental Oceanography, Qingdao (China); City University of Hong Kong, CityU-IAP Laboratory for Atmospheric Sciences, Department of Physics and Material Sciences, Hong Kong (China); Zhou, Wen [City University of Hong Kong, CityU-IAP Laboratory for Atmospheric Sciences, Department of Physics and Material Sciences, Hong Kong (China); Wei, Ke [Chinese Academy of Science, Center for Monsoon System Research, IAP, Beijing (China); City University of Hong Kong, CityU-IAP Laboratory for Atmospheric Sciences, Department of Physics and Material Sciences, Hong Kong (China)

    2010-01-15

    In a weakly nonlinear model how an initial dipole mode develops to the North Atlantic Oscillation (NAO) in a localized shifting jet under the prescribed eddy forcing is examined. It is found that the zonal structure of the eddy-driven NAO anomaly is not only dominated by the longitudinal distribution of the preexisting Atlantic storm track, but also by the initial condition of the NAO anomaly itself associated with the interaction between a localized shifting jet and a topographic standing wave over the Atlantic basin. When both the initial NAO anomaly and the eddy vorticity forcing in the prior Atlantic storm track are more zonally localized, the subsequent eddy-driven NAO anomaly can be more zonally isolated and asymmetric. But, it seems that the shape of the initial NAO anomaly associated with the latitudinal shift of a prior Atlantic jet plays a more important role in producing the zonal asymmetry of subsequent NAO patterns. The zonal asymmetry of the NAO anomaly can be enhanced as the height of topography increases. In addition, it is further found that blocking events occur easily over the Europe continent through the decaying of positive-phase NAO events. However, prior to the positive-phase NAO life cycle the variability in each of three factors: the Atlantic jet, the eddy vorticity forcing in the Atlantic storm track and the initial NAO anomaly can result in a variation in the blocking activity over the Europe sector in strength, duration, position and pattern. (orig.)

  11. High prevalence of occult hepatitis C virus infection in patients with primary and secondary glomerular nephropathies.

    Science.gov (United States)

    Castillo, Inmaculada; Martinez-Ara, Jorge; Olea, Teresa; Bartolomé, Javier; Madero, Rosario; Hernández, Eduardo; Bernis, Carmen; Aguilar, Ana; Quiroga, Juan A; Carreño, Vicente; Selgas, Rafael

    2014-09-01

    The association of hepatitis C virus (HCV) infection and glomerulonephritis is well known. However, the relationship between immune-mediated glomerulonephritis and occult HCV, characterized by the presence of HCV-RNA in liver or in peripheral blood mononuclear cells in the absence of serological markers, is unknown. We tested this in 113 anti-HCV-negative patients; 87 with immune-mediated glomerulonephritis and 26 controls with hereditary glomerular nephropathies. All patients were serum HCV-RNA negative by conventional real-time PCR. Significantly, occult HCV-RNA (detectable viral RNA in peripheral blood mononuclear cells or in serum after ultracentrifugation) was found in 34 of 87 patients with immune-mediated glomerulonephritis versus 1 of 26 control patients. The serum creatinine levels were significantly higher in patients with immune-mediated glomerulonephritis with than in those without occult HCV (1.5 versus 1.1 mg/dl, respectively). A multivariate analysis adjusted for gender showed a significantly increased risk of occult HCV in patients with immune-mediated glomerulonephritis versus the controls (odds ratio of 13.29). Progression to end-stage renal disease tended to be faster in patients with immune-mediated glomerulonephritis and occult HCV than in the negative cases. Thus, occult HCV is strongly associated with immune-mediated glomerulonephritis and may have a role in the progression of the disease.

  12. The Scythe and the Pentagram: Santa Muerte from Folk Catholicism to Occultism

    Directory of Open Access Journals (Sweden)

    Manon Hedenborg-White

    2016-12-01

    Full Text Available Santa Muerte is establishing a presence among practitioners of contemporary occultism in Europe and North America. The occult milieu is highly different from the Mexican cult of Santa Muerte, having a strong heritage of secrecy and tradition as social capital and being mostly middle-class in orientation. Nonetheless, this Catholic folk saint with a mostly pragmatic, popular, and grassroots cult is becoming increasingly popular among occultists. Based on a survey of three recent books on Santa Muerte geared towards an Anglophone, occult audience, it is therefore the aim of this article to understand how and why the Skeleton Saint is attracting adherents in the occult milieu, by analyzing the underlying causes of this growing trend, as well as the conditions shaping it. It is the overall argument of this article that the beginning reception of Santa Muerte in occultism is a result of perceived needs and demands specific to the occult milieu rather than characteristics inherent in the symbol itself, and that an analysis of the ways in which she is spreading outside of her original sociocultural context must be guided by an understanding of the novel one she is integrated in.

  13. High-order ionospheric effects on electron density estimation from Fengyun-3C GPS radio occultation

    Science.gov (United States)

    Li, Junhai; Jin, Shuanggen

    2017-03-01

    GPS radio occultation can estimate ionospheric electron density and total electron content (TEC) with high spatial resolution, e.g., China's recent Fengyun-3C GPS radio occultation. However, high-order ionospheric delays are normally ignored. In this paper, the high-order ionospheric effects on electron density estimation from the Fengyun-3C GPS radio occultation data are estimated and investigated using the NeQuick2 ionosphere model and the IGRF12 (International Geomagnetic Reference Field, 12th generation) geomagnetic model. Results show that the high-order ionospheric delays have large effects on electron density estimation with up to 800 el cm-3, which should be corrected in high-precision ionospheric density estimation and applications. The second-order ionospheric effects are more significant, particularly at 250-300 km, while third-order ionospheric effects are much smaller. Furthermore, the high-order ionospheric effects are related to the location, the local time, the radio occultation azimuth and the solar activity. The large high-order ionospheric effects are found in the low-latitude area and in the daytime as well as during strong solar activities. The second-order ionospheric effects have a maximum positive value when the radio occultation azimuth is around 0-20°, and a maximum negative value when the radio occultation azimuth is around -180 to -160°. Moreover, the geomagnetic storm also affects the high-order ionospheric delay, which should be carefully corrected.

  14. Evaluation and Improved Use of Fecal Occult Blood Test in the Constipated Child.

    Science.gov (United States)

    Kilway, Denise M

    2016-01-01

    This quality improvement project examined the use of fecal occult blood test in the constipated child in a pediatric gastroenterology outpatient clinic. A retrospective chart review was completed on 100 children seen for an initial visit with the gastroenterology provider. The number of fecal occult blood tests performed and the child's coinciding symptoms were tallied and compared with the North American Society of Pediatric Gastroenterology, Hepatology, and Nutrition recommendations. An educational intervention was held with the pediatric gastroenterology providers consisting of a PowerPoint presentation summarizing aims of the quality improvement project and reviewing recommendations for use of fecal occult blood test in the constipated child. Pre- and post-intervention chart review data sets were compared. Results showed a 19.6% decrease in the use of fecal occult blood tests performed during the post-intervention timeframe. However, when used in conjunction with North American Society of Pediatric Gastroenterology, Hepatology, and Nutrition recommendations, the appropriateness of fecal occult blood test use increased by 71.4% in the post-intervention patients. Reviewing the recommendations with gastroenterology providers assisted in optimizing the meaningful use of fecal occult blood test, improving quality and safety of care for children seen in the pediatric gastroenterology outpatient clinic.

  15. Climatology and trends in the forcing of the stratospheric zonal-mean flow

    Directory of Open Access Journals (Sweden)

    E. Monier

    2011-04-01

    Full Text Available The momentum budget of the Transformed Eulerian-Mean (TEM equation is calculated using the European Centre for Medium-Range Weather Forecasts (ECMWF Re-Analysis (ERA-40. This study outlines the considerable contribution of unresolved waves, dominated by gravity waves, to the forcing of the zonal-mean flow. A trend analysis, from 1980 to 2001, shows that the onset and break down of the Northern Hemisphere (NH stratospheric polar night jet has a tendency to occur later. This temporal shift is associated with long-term changes in the planetary wave activity that are mainly due to synoptic waves. In the Southern Hemisphere (SH, the polar vortex shows a tendency to persist further into the SH summertime. This is associated with a statistically significant decrease in the intensity of the stationary EP flux divergence over the 1980–2001 period. Ozone depletion is well known for strengthening westerly winds through the thermal wind balance, which in turn causes a reduction in wave activity in high latitudes. This study suggests that the decrease in planetary wave activity provides an important feedback to the zonal wind as it delays the breakdown of the polar vortex. Finally, we identify long-term changes in the Brewer-Dobson circulation that, this study suggests, are largely caused by trends in the planetary wave activity during winter and by trends in the gravity wave forcing otherwise.

  16. Dynamical effect of the zonal wind anomalies over the tropical western Pacific on ENSO cycles

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The circulation and zonal wind anomalies in the lower troposphere over the equatorial western Pacific and their roles in the developing and decaying processes of the 1982-1983, 1986-1987, 1991-1992 and 1997-1998 El Nino events and the occurrence of La Nina events are analyzed by using the observed data in this paper. The results show that before the developing stage of these El Nino events, there were cyclonic circulation anomalies in the lower troposphere over the tropical western Pacific, and the anomalies brought the westerly anomalies over the Indonesia and the tropical western Pacific. However, when the El Nino events developed to their mature phase, there were anticyclonic circulation anomalies in the lower troposphere over the tropical western Pacific, and the anomalies made the easterly anomalies appear over the tropical western Pacific. A simple, dynamical model of tropical ocean is used to calculate the response of the equatorial oceanic waves to the observed anomalies of wind stress near the sea surface of the equatorial Pacific during the 1997/98 ENSO cycle, which was the strongest one in the 20th century.It is shown that the zonal wind stress anomalies have an important dynamical effect on the development and decay of this El Nino event and the occurrence of the following La Nina event.

  17. On the long-term variability of Jupiter and Saturn zonal winds

    Science.gov (United States)

    Sanchez-Lavega, A.; Garcia-Melendo, E.; Hueso, R.; Barrado-Izagirre, N.; Legarreta, J.; Rojas, J. F.

    2012-12-01

    We present an analysis of the long-term variability of Jupiter and Saturn zonal wind profiles at their upper cloud level as retrieved from cloud motion tracking on images obtained at ground-based observatories and with different spacecraft missions since 1979, encompassing about three Jovian and one Saturn years. We study the sensitivity and variability of the zonal wind profile in both planets to major planetary-scale disturbances and to seasonal forcing. We finally discuss the implications that these results have for current model efforts to explain the global tropospheric circulation in these planets. Acknowledgements: This work has been funded by Spanish MICIIN AYA2009-10701 with FEDER support, Grupos Gobierno Vasco IT-464-07 and UPV/EHU UFI11/55. [1] Sánchez-Lavega A., et al., Icarus, 147, 405-420 (2000). [2] García-Melendo E., Sánchez LavegaA., Icarus, 152, 316-330 (2001) [3] Sánchez-Lavega A., et al., Nature, 423, 623-625 (2003). [4] García-Melendo E., et al., Geophysical Research Letters, 37, L22204 (2010).

  18. The Brown Alga Stypopodium zonale (Dictyotaceae: A Potential Source of Anti-Leishmania Drugs

    Directory of Open Access Journals (Sweden)

    Deivid Costa Soares

    2016-09-01

    Full Text Available This study evaluated the anti-Leishmania amazonensis activity of a lipophilic extract from the brown alga Stypopodium zonale and atomaric acid, its major compound. Our initial results revealed high inhibitory activity for intracellular amastigotes in a dose-dependent manner and an IC50 of 0.27 μg/mL. Due to its high anti-Leishmania activity and low toxicity toward host cells, we fractionated the lipophilic extract. A major meroditerpene in this extract, atomaric acid, and its methyl ester derivative, which was obtained by a methylation procedure, were identified by nuclear magnetic resonance (NMR spectroscopy. Both compounds inhibited intracellular amastigotes, with IC50 values of 20.2 μM (9 μg/mL and 22.9 μM (10 μg/mL, and selectivity indexes of 8.4 μM and 11.5 μM. The leishmanicidal activity of both meroditerpenes was independent of nitric oxide (NO production, but the generation of reactive oxygen species (ROS may be at least partially responsible for the amastigote killing. Our results suggest that the lipophilic extract of S. zonale may represent an important source of compounds for the development of anti-Leishmania drugs.

  19. The switching between zonal and blocked mid-latitude atmospheric circulation: a dynamical system perspective

    Science.gov (United States)

    Faranda, Davide; Masato, Giacomo; Moloney, Nicholas; Sato, Yuzuru; Daviaud, Francois; Dubrulle, Bérengère; Yiou, Pascal

    2016-09-01

    Atmospheric mid-latitude circulation is dominated by a zonal, westerly flow. Such a flow is generally symmetric, but it can be occasionally broken up by blocking anticyclones. The subsequent asymmetric flow can persist for several days. In this paper, we apply new mathematical tools based on the computation of an extremal index in order to reexamine the dynamical mechanisms responsible for the transitions between zonal and blocked flows. We discard the claim that mid-latitude circulation features two distinct stable equilibria or chaotic regimes, in favor of a simpler mechanism that is well understood in dynamical systems theory: we identify the blocked flow as an unstable fixed point (or saddle point) of a single basin chaotic attractor, dominated by the westerlies regime. We also analyze the North Atlantic Oscillation and the Arctic Oscillation atmospheric indices, whose behavior is often associated with the transition between the two circulation regimes, and investigate analogies and differences with the bidimensional blocking indices. We find that the Arctic Oscillation index, which can be thought as a proxy for a hemispheric average of the Tibaldi-Molteni blocking index, tracks unstable fixed points. On the other hand, the North Atlantic Oscillation, representative only for local properties of the North Atlantic blocking dynamics, does not show any trace of the presence of unstable fixed points of the dynamics.

  20. The Brown Alga Stypopodium zonale (Dictyotaceae): A Potential Source of Anti-Leishmania Drugs.

    Science.gov (United States)

    Soares, Deivid Costa; Szlachta, Marcella Macedo; Teixeira, Valéria Laneuville; Soares, Angelica Ribeiro; Saraiva, Elvira Maria

    2016-09-08

    This study evaluated the anti-Leishmania amazonensis activity of a lipophilic extract from the brown alga Stypopodium zonale and atomaric acid, its major compound. Our initial results revealed high inhibitory activity for intracellular amastigotes in a dose-dependent manner and an IC50 of 0.27 μg/mL. Due to its high anti-Leishmania activity and low toxicity toward host cells, we fractionated the lipophilic extract. A major meroditerpene in this extract, atomaric acid, and its methyl ester derivative, which was obtained by a methylation procedure, were identified by nuclear magnetic resonance (NMR) spectroscopy. Both compounds inhibited intracellular amastigotes, with IC50 values of 20.2 μM (9 μg/mL) and 22.9 μM (10 μg/mL), and selectivity indexes of 8.4 μM and 11.5 μM. The leishmanicidal activity of both meroditerpenes was independent of nitric oxide (NO) production, but the generation of reactive oxygen species (ROS) may be at least partially responsible for the amastigote killing. Our results suggest that the lipophilic extract of S. zonale may represent an important source of compounds for the development of anti-Leishmania drugs.

  1. The Brown Alga Stypopodium zonale (Dictyotaceae): A Potential Source of Anti-Leishmania Drugs

    Science.gov (United States)

    Soares, Deivid Costa; Szlachta, Marcella Macedo; Teixeira, Valéria Laneuville; Soares, Angelica Ribeiro; Saraiva, Elvira Maria

    2016-01-01

    This study evaluated the anti-Leishmania amazonensis activity of a lipophilic extract from the brown alga Stypopodium zonale and atomaric acid, its major compound. Our initial results revealed high inhibitory activity for intracellular amastigotes in a dose-dependent manner and an IC50 of 0.27 μg/mL. Due to its high anti-Leishmania activity and low toxicity toward host cells, we fractionated the lipophilic extract. A major meroditerpene in this extract, atomaric acid, and its methyl ester derivative, which was obtained by a methylation procedure, were identified by nuclear magnetic resonance (NMR) spectroscopy. Both compounds inhibited intracellular amastigotes, with IC50 values of 20.2 μM (9 μg/mL) and 22.9 μM (10 μg/mL), and selectivity indexes of 8.4 μM and 11.5 μM. The leishmanicidal activity of both meroditerpenes was independent of nitric oxide (NO) production, but the generation of reactive oxygen species (ROS) may be at least partially responsible for the amastigote killing. Our results suggest that the lipophilic extract of S. zonale may represent an important source of compounds for the development of anti-Leishmania drugs. PMID:27618071

  2. NON-ZONAL BAROCLINIC INSTABILITY IN THE NORTH PACIFIC SUBTROPICAL COUNTERCURRENT

    Institute of Scientific and Technical Information of China (English)

    LU Yan; LUO De-hai

    2004-01-01

    Observations indicated that in the region of the Subtropical Countercurrent(STCC)over the Pacific(140°E-170°W,19°N-28°N),the eddy kinetic energy over the western side is much higher than that over the eastern side.The cause of such a behavior was theoretically investigated in this paper.The calculation of geostrophic current in this region indicates that there are relatively strong meridional geostrophic currents in this region even though the zonal current is dominant in most seasons.Using a 2.5-layer reduced-gravity model,baroclinic instability of non-zonal current was discussed.It is found that at the western side of STCC the vertical shear of the meridional geostrophic current will be in favor of the baroclinic instability,but at its eastern side it will suppress baroclinic instability,thus causing the growth of eddies over the western side much faster than that over the eastern side.

  3. The emergence of zonal jets in forced rotating shallow water turbulence: A laboratory study

    Science.gov (United States)

    Espa, S.; Di Nitto, G.; Cenedese, A.

    2010-11-01

    The emergence of a sequence of alternating intense and elongated eastward-westward bands i.e. zonal jets in the atmosphere of the giant planets and in Earth's oceans have been widely investigated. Nevertheless jets formation and role as material barriers remain still unclear. Jets are generated in a quasi-2D turbulent flow due to the latitudinal variation of the Coriolis parameter (the so-called β-effect) which modifies the inverse cascade process channeling energy towards zonal modes. In previous experiments we have investigated the impact of the variation of the rotation rate, of the domain geometry and of the initial spectra on jets organization in a decaying regime. In this work we investigate the formation of jets in a continuously forced flow, we characterize the observed regime and also we attempt to verify the existence of an universal regime corresponding to the so-called zonostrophic turbulence. The experimental set-up consists of a rotating tank where turbulence is generated by electromagnetically forcing a shallow layer of an electrolyte solution, and the variation of the Coriolis parameter has been simulated by the parabolic profile assumed by the free surface of the fluid under rotation. Flow measurements have been performed using image analysis.

  4. Efficiency prediction for a low head bulb turbine with SAS SST and zonal LES turbulence models

    Science.gov (United States)

    Jošt, D.; Škerlavaj, A.

    2014-03-01

    A comparison between results of numerical simulations and measurements for a 3-blade bulb turbine is presented in order to determine an appropriate numerical setup for accurate and reliable simulations of flow in low head turbines. Numerical analysis was done for three angles of runner blades at two values of head. For the smallest blade angle the efficiency was quite accurately predicted, but for the optimal and maximal blade angles steady state analysis entirely failed to predict the efficiency due to underestimated torque on the shaft and incorrect results in the draft tube. Transient simulation with SST did not give satisfactory results, but with SAS and zonal LES models the prediction of efficiency was significantly improved. From the results obtained by SAS and zonal LES the interdependence between turbulence models, vortex structures in the flow, values of eddy viscosity and flow energy losses in the draft tube can be seen. Also the effect of using the bounded central differential scheme instead of the high resolution scheme was evident. To test the effect of grid density, simulations were performed on four grids. While a difference between results obtained on the basic grid and on the fine grid was small, the results obtained on the coarse grids were not satisfactory.

  5. Rapid diagnosis of occult abscesses using sup 99m Tc-labeled monoclonal antibodies

    Energy Technology Data Exchange (ETDEWEB)

    Coons, T.A.; Rhodes, B.A. (RhoMed, Inc., Albuquerque, NM (USA)); Thakur, M.L. (Thomas Jefferson Univ., Philadelphia, PA (USA)); Marcus, C.S. (Harbor-UCLA Medical Center, Torrance, CA (USA)); Ballou, B. (Pittsburgh Univ., PA (USA))

    1991-01-01

    Acute infections, such as appendicitis and occult infections in AIDS patients, can be diagnosed within two hours by gamma scintigraphy after i.v. administration of {sup 99m}Tc labeled antibodies reactive with human granulocytes. The antibody, murine IgM anti-SSEA-1, is partially reduced using Sn(II) to expose and protect reactive sulfide groups. The antibody is then purified, stannous tartrate and stabilizers are added, and the mixture is lyophilized. To label, sodium pertechnetate is added. After a 15 minute incubation the tracer drug is injected. The rate of accumulation and degree of concentration at the site of infection is presumptively determinative of the severity of the infection. Acceptance criteria and tests for the {sup 99m}Tc labeled antibody product have been established and validated. Greater than 93% of the {sup 99m}Tc is firmly bound to the protein as determined by quantitative HPLC. Radiochemical impurities, colloidal {sup 99m}Tc and free pertechnetate are together less than 4% as determined by thin layer chromatography. The immunoreactive fraction, measured by binding to solid phase antigen, and affinity measured be ELISA, are unchanged by the {sup 99m}Tc-direct labeling process. Two hour blood clearance in rats is within 90% of the value of the {sup 125}I labeled analog. The immunoreactive fraction decreases less than 10% when incubated in human plasma for 24 hours. This method has been compared to other direct labeling methods, and found to give higher radiochemical yields. 5 figs.

  6. Solar-QBO Interaction and Its Impact on Stratospheric Ozone in a Zonally Averaged Photochemical Transport Model of the Middle Atmosphere

    Science.gov (United States)

    2007-08-28

    Satellite (UARS). In general, the CHEM2D zonal winds show good agreement with the UARS clima - tology, although there is an easterly bias in the CHEM2D...spheric ozone [e.g., WMO, 1991; Harris et al., 1998, and references therein]. The standard approach is to assume that the temporal behavior of a zonally...representation of the zonal wind QBO is only an approximation of the true zonal wind QBO, and as such may not capture all the temporal variability in the

  7. RELATIONSHIPS BETWEEN ZONAL WIND ANOMALIES IN HIGH AND LOW TROPOSPHERE AND ANNUAL FREQUENCY OF NW PACIFIC TROPICAL CYCLONES

    Institute of Scientific and Technical Information of China (English)

    GONG Zhen-song; HE Min

    2007-01-01

    Relationships between large-scale zonal wind anomalies and annual frequency of NW Pacific tropical cyclones and possible mechanisms are investigated with the methods of correlation and composition.It is indicated that when △ U200-△U850 >0 in the eastern tropical Pacific and △ U200- △U850 <0 in western tropical Pacific, the Walker cell is stronger in the Pacific tropical region and the annual frequency of NW Pacific tropical cyclone are above normal. In the years with zonal wind anomalies, the circulation of high and low troposphere and the vertical motions in the troposphere have significant characteristics. In the time scale of short-range climate prediction, zonal wind anomalies in high and low troposphere are useful as a preliminary signal of the annual frequency prediction of NW Pacific tropical cyclones.

  8. Novel use of a radiolabelled antibody against stage specific embryonic antigen for the detection of occult abscesses in mammals

    Science.gov (United States)

    Thakur, Madhukar L.

    1990-01-01

    The invention discloses improved reagents containing antibodies against stage specific embryonic antigen-1 antibodies and improved methods for detection of occult abscess and inflammation using the improved reagents.

  9. Advance in investigation of zonal disintegration phenomenon%分区破裂化现象的研究进展

    Institute of Scientific and Technical Information of China (English)

    戚承志; 钱七虎; 王明洋; 罗健

    2011-01-01

    通过对分区破裂化现象的发现过程进行回顾、对分区破裂化现象的研究现状进行综述,对深部巷道围岩的受力变形的特点有了更好的认识,并利用弹塑性理论、断裂力学理论、非线性科学理论等对分区破裂化现象形成的机理进行了探索,得到了一些有益的结论.在现场观测到了分区破裂化现象,从试验上再现了分区破裂化现象的一些主要特点,在数值模拟方面能够定性地模拟这一现象.但还有很多问题没有解决,包括岩体的力学性质及结构特性对于分区破裂化现象时间演化过程的影响、分区破裂化现象与受损岩石变形增量变符号现象之间的关系、岩爆与分区破裂化现象之间的关系问题等.%The finding process of the zonal disintegration phenomenon was reviewed, and the state-of-the-art of investigations of zonal disintegration phenomenon overviewed. The review shows that our understanding on the stressing and the deformation of the rock mass near the deep level openings has been greatly improved. This phenomenon was investigated with the help of the elasticity and plasticity theories, fracture mechanics and nonlinear science etc. , and many helpful conclusions reached. In situ observations the existence of zonal disintegration phenomenon was observed, laboratory model experiments reproduced the main features of zonal disintegration phenomenon,and numerical modeling qualitatively reproduced zonal disintegration phenomenon. But many problems still exist, including the influence of the mechanical and the structural properties of the rock mass on the temporal evolution process of the zonal disintegration, the relationship between the zonal disintegration and the phenomenon of the sign change of deformation increment after the beginning of the damaging process in rock, the relationship between the zonal disintegration and the rock bursts etc.

  10. Zonal characterization of hillslope erosion processes in a semi-arid high mountain catchment

    Science.gov (United States)

    Torres, Raquel; Millares, Agustín; Aguilar, Cristina; Moñino, Antonio; Ángel Losada, Miguel; José Polo, María

    2013-04-01

    Mediterranean and semi-arid catchments, generally suffer heterogeneous erosive processes at different spatio-temporal scales which produce, in a synergistic manner, a large amount of sediment supply. In mountainous catchments, the influence of pluvio-nival hydrological regime leads to a clear subdivision into homogeneous zones regarding the nature of hillslope processes. Here, a distinction could be addressed with 1) subsurface erosion due to saturated soil by intense snowmelt pulses and 2) steepest mid-mountain soil loss with rill/interrill, small-scale landslides and ephemeral or permanent gullying. Furthermore, the associated channels in these areas are formed by wide alluvial floodplains with important bedload contributions. This complexity conditions the evaluation of erosion and monitoring at catchment scale with elevated costs in time, devices and staff. The catchment of the Guadalfeo river encloses 1200 km², with important presence of snow in the summits height on its right margin, and semiarid low range hills with very erodible soils on its left margin. Gully erosion, landslides and stream bed-load processes, extremely actives in this area, are responsible of a real problem of soil loss and desertification with a high associated cost. This work suggests a methodology for the zonal assessment of different erosive processes taking into account the described heterogeneity and the reduction of research costs. To do this, high resolution bathymetric and topographic surveys supported in a reservoir (110 hm3) allowed the differentiation of bedload and suspended sediments as both are deposited in different locations and hence the validation of the hillslope sediment yield. In parallel, measurements in homogeneous areas were selected in order to obtain zonal results to achieve the representative processes involved. The use of portable samplers allows the remote changing of sampling routines, and thus to capture the temporal scale of the processes and the

  11. The contribution of occult precipitation to nutrient deposition on the west coast of South Africa.

    Science.gov (United States)

    Nyaga, Justine M; Neff, Jason C; Cramer, Michael D

    2015-01-01

    The Strandveld mediterranean-ecosystem of the west coast of South Africa supports floristically diverse vegetation growing on mostly nutrient-poor aeolian sands and extending from the Atlantic Ocean tens of kilometers inland. The cold Benguela current upwelling interacts with warm onshore southerly winds in summer causing coastal fogs in this region. We hypothesized that fog and other forms of occult precipitation contribute moisture and nutrients to the vegetation. We measured occult precipitation over one year along a transect running inland in the direction of the prevailing wind and compared the nutrient concentrations with those in rainwater. Occult deposition rates of P, N, K, Mg, Ca, Na, Al and Fe all decreased with distance from the ocean. Furthermore, ratios of cations to Na were similar to those of seawater, suggesting a marine origin for these. In contrast, N and P ratios in occult precipitation were higher than in seawater. We speculate that this is due to marine foam contributing to occult precipitation. Nutrient loss in leaf litter from dominant shrub species was measured to indicate nutrient demand. We estimated that occult precipitation could meet the demand of the dominant shrubby species for annual N, P, K and Ca. Of these species, those with small leaves intercepted more moisture and nutrients than those with larger leaves and could take up foliar deposits of glycine, NO3(-), NH4(+) and Li (as tracer for K) through leaf surfaces. We conclude that occult deposition together with rainfall deposition are potentially important nutrient and moisture sources for the Strandveld vegetation that contribute to this vegetation being floristically distinct from neighbouring nutrient-poor Fynbos vegetation.

  12. The Calar Alto lunar occultation program: update and new results

    CERN Document Server

    Richichi, A; Merino, M; Otazu, X; Nuñez, J; Prades, A; Thiele, U; Pérez-Ramírez, D; Montojo, F J

    2006-01-01

    We present an update of the lunar occultation program which is routinely carried out in the near-IR at the Calar Alto Observatory. A total of 350 events were recorded since our last report (Fors et al. \\cite{fors04}). In the course of eight runs we have observed, among others, late-type giants, T-Tauri stars, and infrared sources. Noteworthy was a passage of the Moon close to the galactic center, which produced a large number of events during just a few hours in July 2004. Results include the determinations of the angular diameter of \\object{RZ Ari}, and the projected separations and brightness ratios for one triple and 13 binary stars, almost all of which representing first time detections. Projected separations range from $0\\farcs09$ to $0\\farcs007$. We provide a quantitative analysis of the performance achieved in our observations in terms of angular resolution and sensitivity, which reach about $0\\farcs003$ and $K \\approx8.5$ mag, respectively. We also present a statistical discussion of our sample, and i...

  13. Atmospheric diurnal variations observed with GPS radio occultation soundings

    Directory of Open Access Journals (Sweden)

    F. Xie

    2010-07-01

    Full Text Available The diurnal variation, driven by solar forcing, is a fundamental mode in the Earth's weather and climate system. Radio occultation (RO measurements from the six COSMIC satellites (Constellation Observing System for Meteorology, Ionosphere and Climate provide nearly uniform global coverage with high vertical resolution, all-weather and diurnal sampling capability. This paper analyzes the diurnal variations of temperature and refractivity from three-year (2007–2009 COSMIC RO measurements in the troposphere and stratosphere between 30° S and 30° N. The RO observations reveal both propagating and trapped vertical structures of diurnal variations, including transition regions near the tropopause where data with high vertical resolution are critical. In the tropics the diurnal amplitude in refractivity shows the minimum around 14 km and increases to a local maximum around 32 km in the stratosphere. The upward propagating component of the migrating diurnal tides in the tropics is clearly captured by the GPS RO measurements, which show a downward progression in phase from stratopause to the upper troposphere with a vertical wavelength of about 25 km. At ~32 km the seasonal variation of the tidal amplitude maximizes at the opposite side of the equator relative to the solar forcing. The vertical structure of tidal amplitude shows strong seasonal variations and becomes asymmetric along the equator and tilted toward the summer hemisphere in the solstice months. Such asymmetry becomes less prominent in equinox months.

  14. Seronegative occult hepatitis C virus infection: clinical implications.

    Science.gov (United States)

    Carreño, Vicente

    2014-11-01

    Occult hepatitis C virus infection (OCI) was first described in anti-HCV and serum HCV-RNA negative patients with abnormal values of liver enzymes but who presented HCV-RNA in liver and in peripheral blood mononuclear cells. Up to now, two types of OCI are recognized: seronegative OCI (anti-HCV and serum HCV-RNA negative) and seropositive OCI (anti-HCV positive and serum HCV-RNA negative). The concept of OCI is still a matter of debate, probably because both types of OCI are not considered as different entities. This review focuses on seronegative OCI. The existence of seronegative OCI has been documented all around the world with the implication of different HCV genotypes (1-4). Seronegative OCI is associated with cryptogenic chronic hepatitis and liver cirrhosis and it may be involved in the appearance of hepatocellular carcinoma. Also seronegative OCI may increase the histological liver damage in chronic hepatitis B and in HIV-infected patients. It may have a negative influence in the natural history of hemodialysis patients and in immune-mediated glomerulonephritis. Seronegative OCI has been detected also in patients with haematological diseases, among healthy subjects and in drug users. Other publications indicate the potential infectivity of seronegative OCI in the setting of family members, sexual partners and liver transplantation. In summary, seronegative OCI may play a role in liver diseases and other human pathologies and may be present in healthy people but larger studies are needed to confirm these findings.

  15. Occult hepatitis C virus infection among Egyptian hemodialysis patients.

    Science.gov (United States)

    Abdelrahim, Soha S; Khairy, Rasha; Esmail, Mona Abdel-Monem; Ragab, Mahmoud; Abdel-Hamid, Mohamed; Abdelwahab, Sayed F

    2016-08-01

    Occult hepatitis C virus (HCV) infection (OCI) was reported in an apparently disease-free state in the absence of liver disease, anti-HCV and HCV-RNA in the serum. The existing data examining the clinical significance of OCI and its potential as a source of HCV infection among hemodialysis patients are very limited. We examined the presence of OCI among patients on maintenance hemodialysis at Minia Governorate, Egypt; an HCV endemic country. A total of 81 subjects with negative markers for HCV were enrolled. HCV-RNA was tested in PBMCs by real-time PCR. For the 81 subjects, the average dialysis duration was 32.7 ± 21.7 months and the average ALT level (±SD) was 26 ± 12 U/L while that of AST was 29 ± 16 U/L. Out of the 81 subjects, three (3.7%) were HCV-RNA positive in PBMCs in the absence of serum anti-HCV and HCV-RNA indicating OCI. The viral load of the OCI subjects ranged from 172 to 4150 IU/ml. History of liver disease was positive in one of the three positive patients. These results highlight the potential risk of HCV transmission from patients within hemodialysis units in Egypt. J. Med. Virol. 88:1388-1393, 2016. © 2016 Wiley Periodicals, Inc.

  16. Occultation Modeling for Radiation Obstruction Effects on Spacecraft Systems

    Science.gov (United States)

    de Carufel, Guy; Li, Zu Qun; Harvey, Jason; Crues, Edwin Z.; Bielski, Paul

    2016-01-01

    A geometric occultation model has been developed to determine line-of-sight obstruction of radiation sources expected for different NASA space exploration mission designs. Example applications includes fidelity improvements for surface lighting conditions, radiation pressure, thermal and power subsystem modeling. The model makes use of geometric two dimensional shape primitives to most effectively model space vehicles. A set of these primitives is used to represent three dimensional obstructing objects as a two dimensional outline from the perspective of an observing point of interest. Radiation sources, such as the Sun or a Moon's albedo is represented as a collection of points, each of which is assigned a flux value to represent a section of the radiation source. Planetary bodies, such as a Martian moon, is represented as a collection of triangular facets which are distributed in spherical height fields for optimization. These design aspects and the overall model architecture will be presented. Specific uses to be presented includes a study of the lighting condition on Phobos for a possible future surface mission, and computing the incident flux on a spacecraft's solar panels and radiators from direct and reflected solar radiation subject to self-shadowing or shadowing by third bodies.

  17. SOLAR OCCULTATION BY TITAN MEASURED BY CASSINI/UVIS

    Energy Technology Data Exchange (ETDEWEB)

    Capalbo, Fernando J.; Benilan, Yves [Laboratoire Interuniversitaire des Systemes Atmospheriques (LISA), UMR 7583 du CNRS, Universites Paris Est Creteil (UPEC) and Paris Diderot - UPD, 61 avenue du General de Gaulle, 94010 Creteil Cedex (France); Yelle, Roger V.; Koskinen, Tommi T.; Sandel, Bill R. [Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721 (United States); Holsclaw, Gregory M.; McClintock, William E., E-mail: fernando.capalbo@lisa.u-pec.fr [Laboratory for Atmospheric and Space Physics, University of Colorado, 3665 Discovery Drive, Boulder, CO 80303 (United States)

    2013-04-01

    We present the first published analysis of a solar occultation by Titan's atmosphere measured by the Ultraviolet Imaging Spectrograph on board Cassini. The data were measured during flyby T53 in 2009 April and correspond to latitudes between 21 Degree-Sign and 28 Degree-Sign south. The analysis utilizes the absorption of two solar emission lines (584 A and 630 A) in the ionization continuum of the N{sub 2} absorption cross section and solar emission lines around 1085 A where absorption is due to CH{sub 4}. The measured transmission at these wavelengths provides a direct estimate of the N{sub 2} and CH{sub 4} column densities along the line of sight from the spacecraft to the Sun, which we inverted to obtain the number densities. The high signal-to-noise ratio of the data allowed us to retrieve density profiles in the altitude range 1120-1400 km for nitrogen and 850-1300 km for methane. We find an N{sub 2} scale height of {approx}76 km and a temperature of {approx}153 K. Our results are in general agreement with those from previous work, although there are some differences. Particularly, our profiles agree, considering uncertainties, with the density profiles derived from the Voyager 1 Ultraviolet Spectrograph data, and with in situ measurements by the Ion Neutral Mass Spectrometer with revised calibration.

  18. Assimilation of GNSS radio occultation observations in GRAPES

    Science.gov (United States)

    Liu, Y.; Xue, J.

    2014-07-01

    This paper reviews the development of the global navigation satellite system (GNSS) radio occultation (RO) observations assimilation in the Global/Regional Assimilation and PrEdiction System (GRAPES) of China Meteorological Administration, including the choice of data to assimilate, the data quality control, the observation operator, the tuning of observation error, and the results of the observation impact experiments. The results indicate that RO data have a significantly positive effect on analysis and forecast at all ranges in GRAPES not only in the Southern Hemisphere where conventional observations are lacking but also in the Northern Hemisphere where data are rich. It is noted that a relatively simple assimilation and forecast system in which only the conventional and RO observation are assimilated still has analysis and forecast skill even after nine months integration, and the analysis difference between both hemispheres is gradually reduced with height when compared with NCEP (National Centers for Enviromental Prediction) analysis. Finally, as a result of the new onboard payload of the Chinese FengYun-3 (FY-3) satellites, the research status of the RO of FY-3 satellites is also presented.

  19. Relative photometry of HAT-P-1b occultations

    CERN Document Server

    Béky, Bence; Gilliland, Ronald L; Bakos, Gáspár Á; Winn, Joshua N; Noyes, Robert W; Sasselov, Dimitar D

    2013-01-01

    We present HST STIS observations of two occultations of the transiting exoplanet HAT-P-1b. By measuring the planet to star flux ratio near opposition, we constrain the geometric albedo of the planet, which is strongly linked to its atmospheric temperature gradient. An advantage of HAT-P-1 as a target is its binary companion ADS 16402 A, which provides an excellent photometric reference, simplifying the usual steps in removing instrumental artifacts from HST time-series photometry. We find that without this reference star, we would need to detrend the lightcurve with the time of the exposures as well as the first three powers of HST orbital phase, and this would introduce a strong bias in the results for the albedo. However, with this reference star, we only need to detrend the data with the time of the exposures to achieve the same per-point scatter, therefore we can avoid most of the bias associated with detrending. Our final result is a 2 sigma upper limit of 0.64 for the geometric albedo of HAT-P-1b betwee...

  20. Pluto's atmosphere from stellar occultations in 2012 and 2013

    CERN Document Server

    Dias-Oliveira, A; Lellouch, E; Vieira-Martins, R; Assafin, M; Camargo, J I B; Braga-Ribas, F; Gomes-Júnior, A R; Benedetti-Rossi, G; Colas, F; Decock, A; Doressoundiram, A; Dumas, C; Emilio, M; Polleri, J Fabrega; Gil-Hutton, R; Gillon, M; Girard, J; Hau, G; Ivanov, V D; Jehin, E; Lecacheux, J; Leiva, R; Lopez-Sisterna, C; Mancini, L; Maury, A; Meza, E; Morales, N; Nagy, L; Opitom, C; Ortiz, J L; Pollock, J; Roques, F; Snodgrass, C; Soulier, J F; Thirouin, A; Vanzi, L; Widemann, T; Reichart, D E; LaCluyze, A P; Haislip, J B; Ivarsen, K M; Dominik, M; Jørgensen, U; Skottfelt, J

    2015-01-01

    We analyze two multi-chord stellar occultations by Pluto observed on July 18th, 2012 and May 4th, 2013, and monitored respectively from five and six sites. They provide a total of fifteen light-curves, twelve of them being used for a simultaneous fit that uses a unique temperature profile, assuming a clear (no-haze) and pure N_2 atmosphere, but allowing for a possible pressure variation between the two dates. We find a solution that fits satisfactorily (i.e. within the noise level) all the twelve light-curves, providing atmospheric constraints between ~1,190 km (pressure ~ 11 \\mubar) and ~ 1,450 km (pressure ~0.1 \\mubar) from Pluto's center. Our main results are: (1) the best-fitting temperature profile shows a stratosphere with strong positive gradient between 1,190 km (at 36 K, 11 \\mubar) and r = 1,215 km (6.0 \\mubar), where a temperature maximum of 110 K is reached; above it is a mesosphere with negative thermal gradient of -0.2 K/km up to ~ 1,390 km (0.25 \\mubar), where, the mesosphere connects itself to ...

  1. Occult HBV Infection: A Faceless Enemy in Liver Cancer Development

    Directory of Open Access Journals (Sweden)

    Jaime Morales-Romero

    2014-04-01

    Full Text Available The hepatitis B virus (HBV represents a worldwide public health problem; the virus is present in one third of the global population. However, this rate may in fact be higher due to occult hepatitis B virus infection (OBI. This condition is characterized by the presence of the viral genome in the liver of individuals sero-negative for the virus surface antigen (HBsAg. The causes of the absence of HBsAg in serum are unknown, however, mutations have been identified that produce variants not recognized by current immunoassays. Epigenetic and immunological host mechanisms also appear to be involved in HBsAg suppression. Current evidence suggests that OBI maintains its carcinogenic potential, favoring the progression of fibrosis and cirrhosis of the liver. In common with open HBV infection, OBI can contribute to the establishment of hepatocellular carcinoma. Epidemiological data regarding the global prevalence of OBI vary due to the use of detection methods of different sensitivity and specificity. In Latin America, which is considered an area of low prevalence for HBV, diagnostic screening methods using gene amplification tests for confirmation of OBI are not conducted. This prevents determination of the actual prevalence of OBI, highlighting the need for the implementation of cutting edge technology in epidemiological surveillance systems.

  2. Survival of occult practices and ideas in modern common sense.

    Science.gov (United States)

    Doering-Manteuffel, Sabine

    2011-05-01

    For a long time rationalism and materialism were the most important ideological undercurrents of the Western world. Since the Enlightenment, in the eighteenth century, they have influenced the Age of Reason. During the past few decades, the so-called New Age originated strong counter-movements have produced a huge number of different new world-views. They are to be considered as part of the wide field of occultism, and run out in different directions. The belief in angels and in the power of fate, the communication with the dead, and the conviction of a life after death are all expressions of a desire to transcend and of a search for higher powers that watch over each person. Additionally, helpers and healers have created a marketplace to promote esoteric services. Media usage, the need to transcend and this new market interested in the magical signal a new era of consciousness in which reason and technology do not contradict mysticism and the transmission of wisdom: these go, instead, hand in hand.

  3. Exploring atmospheric blocking with GPS radio occultation observations

    Directory of Open Access Journals (Sweden)

    L. Brunner

    2015-12-01

    Full Text Available Atmospheric blocking has been closely investigated in recent years due to its impact on weather and climate, such as heat waves, droughts, and flooding. We use, for the first time, satellite-based observations from Global Positioning System (GPS radio occultation (RO and explore their ability to resolve blocking in order to potentially open up new avenues complementing models and re-analyses. RO delivers globally available and vertically high resolved profiles of atmospheric variables such as temperature and geopotential height (GPH. Applying a standard blocking detection algorithm we find that RO data robustly capture blocking as demonstrated for two well-known blocking events over Russia in summer 2010 and over Greenland in late winter 2013. During blocking episodes, vertically resolved GPH gradients show a distinct anomalous behavior compared to climatological conditions up to 300 hPa and sometimes even further up to the tropopause. The accompanied increase in GPH of up to 300 m in the upper troposphere yields a pronounced tropopause height increase. Corresponding temperatures rise up to 10 K in the middle and lower troposphere. These results demonstrate the feasibility and potential of RO to detect and resolve blocking and in particular to explore the vertical structure of the atmosphere during blocking episodes. This new observation-based view is available globally at the same quality so that also blocking in the Southern Hemisphere can be studied with the same reliability as in the Northern Hemisphere.

  4. Occult radiological effects of lipomatosis of the lumbosacral plexus

    Energy Technology Data Exchange (ETDEWEB)

    Mahan, Mark A. [Barrow Neurological Institute, Phoenix, AZ (United States); Howe, B.M.; Amrami, Kimberly K. [Mayo Clinic, Department of Radiology, Rochester, MN (United States); Spinner, Robert J. [Mayo Clinic, Department of Neurosurgery, Rochester, MN (United States); Mayo Clinic, Department of Orthopedics, Rochester, MN (United States); Mayo Clinic, Rochester, MN (United States)

    2014-07-15

    Lipomatosis of nerve (LN) is a condition of massive peripheral nerve enlargement frequently associated with hypertrophy within the distribution of the nerve, and most commonly affecting the distal limbs. We sought to understand if LN of the lumbosacral plexus would be associated with the trophic effects of LN on surrounding tissue within the pelvis, which may be clinically occult, but present on MRI. Fifty-one cases of LN, confirmed by pathology or pathognomonic appearance on MRI, were reviewed. Patients with LN of the sciatic nerve were investigated for radiological signs suggestive of overgrowth. Five patients had involvement of the sciatic nerve, 4 of whom had MR imaging of the pelvis. Three patients had LN involving the lumbosacral plexus, and one patient had isolated involvement of the sciatic nerve. All patients with involvement of the lumbosacral plexus demonstrated previously unrecognized evidence of nerve territory overgrowth in the pelvis, including: LN, profound adipose proliferation, muscle atrophy and fatty infiltration, and bone hypertrophy and ankylosis. The patient with LN involving the intrapelvic sciatic nerve, but not the lumbosacral plexus did not demonstrate any radiological evidence of pelvic overgrowth. LN is broader in anatomical reach than previously understood. Proximal plexal innervation may be involved, with a consequent effect on axial skeleton and intrapelvic structures. (orig.)

  5. MRI of occult sacral insufficiency fractures following radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Mammone, J.F. [Dept. of Radiology, Thomas Jefferson Univ. Hospital, and Jefferson Medical Coll., Philadelphia, PA (United States); Schweitzer, M.E. [Dept. of Radiology, Thomas Jefferson Univ. Hospital, and Jefferson Medical Coll., Philadelphia, PA (United States)

    1995-02-01

    Following radiation therapy, marrow abnormalities noted on magnetic resonance imaging (MRI) are frequent and may mimic metastases. Specific radiotherapy changes are usually easily identifiable; however, traumatic lesions cause more interpretive difficulties. We assessed the incidence and MRI characteristics of insufficiency fractures in this population. During a 5-year span (1987-1991), 546 patients received pelvic radiotherapy for primary malignancies. MRI was performed in 25 of these patients at least 3 months after treatment. The mean dose in this group was 53 Gy. These MRI scans were retrospectively reviewed for the appearance of the sacrum with particular attention to the presence of insufficiency fractures. This was correlated with clinical course and scintigraphic findings. Presumed insufficiency fractures on MRI paralleled the sacral side of the sacroiliac joint, enhanced with Gd-DTPA, were most prominent or initially seen anteriorly, and had ill-defined margins on all imaging sequences. The incidence of occult sacral insufficiency fractures was at least 20%. Insufficiency fractures of the sacrum in the post-radiotherapy patient are a relatively frequent occurrence which can mimic metastases. Consideration of this phenomenon and knowledge of differential features may avoid overdiagnosis of osseous metastases. (orig.)

  6. The evaluation and management of obscure and occult gastrointestinal bleeding.

    Science.gov (United States)

    Singh, Vijay; Alexander, Jeffrey A

    2009-01-01

    Gastrointestinal (GI) bleeding is a common clinical presentation increasing in an aging population, frequently requiring hospitalization and emergent intervention, with significant morbidity, mortality, and costs. It may manifest overtly as hematemesis, melena, or hematochezia, or as an asymptomatic occult bleed. Management typically involves an esophagogastroduodenoscopy or a colonoscopy; these in combination sometimes do not identify a source of bleeding, with the source remaining obscure. Further work up to identify an obscure source frequently requires radiologically detecting the leakage of an intravascular tracer (using tagged red blood cells or angiography) with brisk bleeding or in other cases CT enterography (CTE) to detect bowel wall changes consistent with a bleeding source. Recent advances including capsule endoscopy, CTE, and double-balloon endoscopy have helped to identify bleeding sources beyond the reach of conventional endoscopy. Clinical decision-making about their use is complex and evolving. Knowing their relative merits and weaknesses including yield, contraindications, complications, and cost is essential in coming up with an appropriate management plan. This review covers the rationale for clinical management of obscure sources of GI bleeding, mentioning the approach to and the yield of conventional methods, with an emphasis on the recent advances mentioned above.

  7. Acute Pseudohepatitis in a Chronic Substance Abuser Secondary to Occult Seat Belt Injury

    Directory of Open Access Journals (Sweden)

    Eric CS Lam

    1999-01-01

    Full Text Available Causes of a massive elevation in serum aminotransferases (aspartate aminotransferase [AST] and alanine aminotransferase [ALT] in the substance-abusing patient include viral hepatitis and drug hepatotoxicity. A patient chronically addicted to injection heroin and cocaine presented to the emergency room in a confused state and was admitted to a medical ward with an AST of 4120 U/L, ALT 3820 U/L and right upper quadrant discomfort. Investigations for viral and hepatotoxic causes for the liver dysfunction revealed only hepatitis C seropositivity. A computed tomogram of the abdomen, however, revealed a significant contusion to the right lobe of the liver consistent with traumatic injury. A motor vehicle accident, in which the patient was wearing a seat belt, and which had occurred a few days before admission and had been thought to be minor, was the cause of the liver dysfunction. Significant blunt abdominal traumatic injuries are usually managed exclusively by surgical trauma units. This case underlines the need for medical specialists to be aware of hepatic contusion injuries and to have a high index of suspicion when investigating unexplained hepatocellular dysfunction in chronic substance abusers who have been in motor vehicle accidents.

  8. Neptune at Summer Solstice: Zonal Mean Temperatures from Ground-Based Observations 2003-2007

    CERN Document Server

    Fletcher, Leigh N; Orton, Glenn S; Hammel, Heidi B; Sitko, Michael L; Irwin, Patrick G J

    2013-01-01

    Imaging and spectroscopy of Neptune's thermal infrared emission is used to assess seasonal changes in Neptune's zonal mean temperatures between Voyager-2 observations (1989, heliocentric longitude Ls=236) and southern summer solstice (2005, Ls=270). Our aim was to analyse imaging and spectroscopy from multiple different sources using a single self-consistent radiative-transfer model to assess the magnitude of seasonal variability. Globally-averaged stratospheric temperatures measured from methane emission tend towards a quasi-isothermal structure (158-164 K) above the 0.1-mbar level, and are found to be consistent with spacecraft observations of AKARI. This remarkable consistency, despite very different observing conditions, suggests that stratospheric temporal variability, if present, is $\\pm$5 K at 1 mbar and $\\pm$3 K at 0.1 mbar during this solstice period. Conversely, ethane emission is highly variable, with abundance determinations varying by more than a factor of two. The retrieved C2H6 abundances are e...

  9. Meridional trapping and zonal propagation of inertial waves in a rotating fluid shell

    CERN Document Server

    Rabitti, Anna

    2014-01-01

    Inertial waves propagate in homogeneous rotating fluids, and constitute a challenging and simplified case study for the broader class of inertio-gravity waves, present in all geophysical and astrophysical media, and responsible for energetically costly processes as diapycnal and angular momentum mixing. However, a complete analytical description and understanding of internal waves in arbitrarily shaped enclosed domains, such as the ocean, or a planet liquid core, is still missing. In this work, the inviscid, linear inertial wave field is investigated by means of three dimensional ray tracing in spherical shell domains, having in mind possible oceanographic applications. Rays are here classically interpreted as representative of energy paths. But in contrast with previous studies, they are now launched with a non-zero initial zonal component allowing for a more realistic, localized forcing, and the development of azimuthal inhomogeneities. We find that meridional planes generally act in the shell geometry as a...

  10. Toroidal symmetry of the geodesic acoustic mode zonal flow in a tokamak plasma.

    Science.gov (United States)

    Zhao, K J; Lan, T; Dong, J Q; Yan, L W; Hong, W Y; Yu, C X; Liu, A D; Qian, J; Cheng, J; Yu, D L; Yang, Q W; Ding, X T; Liu, Y; Pan, C H

    2006-06-30

    The toroidal symmetry of the geodesic acoustic mode (GAM) zonal flows is identified with toroidally distributed three step Langmuir probes at the edge of the HuanLiuqi-2A (commonly referred to as HL-2A) tokamak plasmas for the first time. High coherence of both the GAM and the ambient turbulence for the toroidally displaced measurements along a magnetic field line is observed, in contrast with the high coherence of the GAM but low coherence of the ambient turbulence when the toroidally displaced measurements are not along the same field line. The radial and poloidal features of the flows are also simultaneously determined. The nonlinear three wave coupling between the high frequency turbulent fluctuations and the flows is demonstrated to be a plausible formation mechanism of the flows.

  11. Computational aspects of zonal algorithms for solving the compressible Navier-Stokes equations in three dimensions

    Science.gov (United States)

    Holst, T. L.; Thomas, S. D.; Kaynak, U.; Gundy, K. L.; Flores, J.; Chaderjian, N. M.

    1985-01-01

    Transonic flow fields about wing geometries are computed using an Euler/Navier-Stokes approach in which the flow field is divided into several zones. The flow field immediately adjacent to the wing surface is resolved with fine grid zones and solved using a Navier-Stokes algorithm. Flow field regions removed from the wing are resolved with less finely clustered grid zones and are solved with an Euler algorithm. Computational issues associated with this zonal approach, including data base management aspects, are discussed. Solutions are obtained that are in good agreement with experiment, including cases with significant wind tunnel wall effects. Additional cases with significant shock induced separation on the upper wing surface are also presented.

  12. On the origin of pre-reversal enhancement of the zonal equatorial electric field

    Directory of Open Access Journals (Sweden)

    M. C. Kelley

    2009-05-01

    Full Text Available In November 2004, a large and variable interplanetary electric field (IEF was felt in the reference frame of the Earth. This electric field penetrated to the magnetic equator and, when the Jicamarca Radio Observatory (JRO was in the dusk sector, resulted in a reversal of the normal zonal component of the field. In turn, this caused a counter-electrojet (CEJ, a westward current rather than the usual eastward current. At the time of the normal pre-reversal enhancement (PRE of the eastward field, the Jicamarca incoherent scatter radar (ISR observed that the westward component became even more westward. Two of the three current explanations for the PRE depend on the neutral wind patterns. However, this unique event was such that the neutral wind-driven dynamos could not have changed. The implication is that the Haerendel-Eccles mechanism, which involves partial closure of the equatorial electrojet (EEJ after sunset, must be the dominant mechanism for the PRE.

  13. Effects of energetic particles on zonal flow generation by toroidal Alfvén eigenmode

    Science.gov (United States)

    Qiu, Z.; Chen, L.; Zonca, F.

    2016-09-01

    Generation of zonal flow (ZF) by energetic particle (EP) driven toroidal Alfvén eigenmode (TAE) is investigated using nonlinear gyrokinetic theory. It is found that nonlinear resonant EP contribution dominates over the usual Reynolds and Maxwell stresses due to thermal plasma nonlinear response. ZF can be forced driven in the linear growth stage of TAE, with the growth rate being twice the TAE growth rate. The ZF generation mechanism is shown to be related to polarization induced by resonant EP nonlinearity. The generated ZF has both the usual meso-scale and micro-scale radial structures. Possible consequences of this forced driven ZF on the nonlinear dynamics of TAE are also discussed.

  14. Present-day zonal wind influences projected Indian Ocean Dipole skewness

    Science.gov (United States)

    Ng, Benjamin; Cai, Wenju

    2016-11-01

    A prominent feature of the Indian Ocean Dipole (IOD) is its positive skewness, where positive phases tend to be stronger in amplitude than the negative phase. Positive IOD events are associated with devastating floods over parts of East Africa and India, while Australia and Indonesia experience dry conditions. Under greenhouse warming, climate models project a weakening of the positive IOD skewness, but their simulation of present-day skewness is too weak. Here we show that this bias and the projected skewness change are related to the simulation of the climatological zonal wind in the central equatorial Indian Ocean. In particular, models with overly weak present-day westerlies, which is a common model bias, generate overly weak present-day skewness and a smaller projected reduction in skewness. Improving the ability of models in simulating stronger westerly winds may lead to stronger present-day simulated skewness and a larger skewness reduction in a warmer climate.

  15. Zonal Distribution of the Erosion-Landslide and Soil Micromorphological Features in Purple Hilly Region

    Institute of Scientific and Technical Information of China (English)

    HE Yurong; LIAO Chaolin; XU Pei; ZHANG Baohua

    2005-01-01

    In the purple hilly region, erosions and landslides are all serious, and it is of great scientific value and practical significance to study their formation mechanism and distribution features there.In this paper, soil micromorphological methods and techniques were used to study the erosion zonal distribution in the region. The results indicated: (1)According to erosion process, the spacial distribution zones of the erosions and landslides in the purple hilly region with different solums were divided into scouring erosion zone, transport-diffusion zone, rocks and soil turbulence zone and sediment-bury zone; (2)The soil micromorphologic taxonomic feature identifying different erosion-landslide zone were found by studying the soil micromorphology of erosive zone in purple hilly region; (3) As for the erosion-landslide formation in the region, besides the external factors, the internal factors were found more important and favorable for landslide formation through the studies on the mieormorphological features of slide soil.

  16. A grid interfacing zonal algorithm for three-dimensional transonic flows about aircraft configurations

    Science.gov (United States)

    Atta, E. H.; Vadyak, J.

    An efficient grid interfacing zonal algorithm has been developed for computing the transonic flow field about three-dimensional multicomponent configurations. The algorithm uses the full-potential formulation and the fully-implicit approximate factorization scheme (AF2). The flow field solution is computed using a component adaptive grid approach in which separate grids are employed for the individual components in the multicomponent configuration, where each component grid is optimized for a particular geometry. The component grids are allowed to overlap, and flow field information is transmitted from one grid to another through the overlap region. An overlapped-grid scheme is implemented for a wing and a wing/pylon/nacelle configuration. Numerical results show that the present algorithm is stable, accurate, and can be used effectively to compute the flow field about complex configurations.

  17. Using box models to quantify zonal distributions and emissions of halocarbons in the background atmosphere.

    Science.gov (United States)

    Elkins, J. W.; Nance, J. D.; Dutton, G. S.; Montzka, S. A.; Hall, B. D.; Miller, B.; Butler, J. H.; Mondeel, D. J.; Siso, C.; Moore, F. L.; Hintsa, E. J.; Wofsy, S. C.; Rigby, M. L.

    2015-12-01

    The Halocarbons and other Atmospheric Trace Species (HATS) of NOAA's Global Monitoring Division started measurements of the major chlorofluorocarbons and nitrous oxide in 1977 from flask samples collected at five remote sites around the world. Our program has expanded to over 40 compounds at twelve sites, which includes six in situ instruments and twelve flask sites. The Montreal Protocol for Substances that Deplete the Ozone Layer and its subsequent amendments has helped to decrease the concentrations of many of the ozone depleting compounds in the atmosphere. Our goal is to provide zonal emission estimates for these trace gases from multi-box models and their estimated atmospheric lifetimes in this presentation and make the emission values available on our web site. We plan to use our airborne measurements to calibrate the exchange times between the boxes for 5-box and 12-box models using sulfur hexafluoride where emissions are better understood.

  18. Nonlinear dynamics of phase space zonal structures and energetic particle physics in fusion plasmas

    CERN Document Server

    Zonca, Fulvio; Briguglio, Sergio; Fogaccia, Giuliana; Vlad, Gregorio; Wang, Xin

    2014-01-01

    A general theoretical framework for investigating nonlinear dynamics of phase space zonal structures is presented in this work. It is then, more specifically, applied to the limit where the nonlinear evolution time scale is smaller or comparable to the wave-particle trapping period. In this limit, both theoretical and numerical simulation studies show that non-adiabatic frequency chirping and phase locking could lead to secular resonant particle transport on meso- or macro-scales. The interplay between mode structures and resonant particles then provides the crucial ingredient to properly understand and analyze the nonlinear dynamics of Alfv\\'en wave instabilities excited by non-perturbative energetic particles in burning fusion plasmas. Analogies with autoresonance in nonlinear dynamics and with superradiance in free electron lasers are also briefly discussed.

  19. Helical electric potential modulation via zonal-flow coupling to resonant magnetic perturbations

    Science.gov (United States)

    Leconte, M.; Kim, J.-H.

    2017-08-01

    Helical modulations of the electric potential were observed in several devices during application of resonant magnetic perturbations (RMPs). To address the implication of the helical modulation on RMP-induced transport, we derive a system of 1D equations for zonal flows (ZFs) and helical potential in the presence of RMPs. As ZFs are turbulence-driven, turbulence plays a major role in this plasma self-organization towards a quasi-equilibrium with 3D helical potential. The model reveals how RMPs modify an initially given a saturated-state of coexisting turbulence and ZFs. It is shown that RMPs trigger a transport bifurcation by allowing energy-transfer out of turbulence-driven ZFs into ZF-driven helical potential.

  20. Comparative phloem Mobility of nickel in nonsenescent plants. [Pisum sativa L. ; Pelargonium zonale L

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, P.M.; Chamel, A.

    1986-06-01

    /sup 63/Ni was applied to nonsenescent source leaves and found to be transported to sink tissues in pea (Pisum saativum L.) and geranium plants (Pelargonium zonale L.). The comparative mobilities (percent tracer transported out of source leaf division % /sup 86/Rb transported) for /sup 63/Ni in peas was 2.12 and in geranium 0.25. The value for the phloem mobile /sup 86/Rb was 1.00. By contrast, the comparative mobility of /sup 45/Ca, which is relatively immobile in the phloem, was low (0.05 in peas, 0.00 in geranium). Interruption of the phloem pathway between source and sink leaves by steam girdling almost completely inhibited /sup 63/Ni accumulation in the sink leaves of both species. The authors conclude that Ni is transported from nonsenescent source leaves to sink tissues via the phloem of leguminous and nonleguminous plants.