3,384 research outputs found
Pulmonary hypertension and heart failure : physiological markers assessed by cardiovascular magnetic resonance
No full textPulmonary hypertension (PH) is clinically and physiologically associated with heart failure, both with reduced and preserved ejection fraction (HFrEF and HFpEF). In HFpEF, the most likely underlying pathophysiological mechanism is an impairment of left ventricular relaxation named diastolic dysfunction. The close relationship between PH, diastolic dysfunction, and heart failure makes it difficult to clearly distinguish between them in clinical practice. Given the challenges around screening and diagnosis of both PH and diastolic dysfunction, better diagnostic tools are needed to complement the existing ones. Cardiovascular magnetic resonance (CMR) is considered the most accurate imaging modality in the assessment of myocardial anatomy and function. Furthermore, CMR offers the possibility of qualitatively and quantitatively assess blood flow in large and medium vessels. Constant technical innovations push to further develop the current clinical capabilities of CMR and enable better and faster diagnosis of cardiovascular diseases.In this thesis, we aimed to expand the current clinical capabilities of CMR in the diagnosis of pulmonary hypertension and diastolic dysfunction, which are not routinely assessed with this imaging modality. In Study I, we investigated the effect of body position in pulmonary blood flow distribution and documented a new variable, termed pulmonary vascular distensibility reserve, possibly related to left atrial pressure. In Study II, we found that CMR has a higher diagnostic yield than echocardiography for estimation of elevated pulmonary artery pressure. In Study III, CMR estimation of pulmonary artery pressure showed very good agreement with invasively measured pressure, and better sensitivity and accuracy than echocardiography. In Study IV, we developed a high temporal resolution CMR method to measure transmitral blood and myocardial tissue velocities, which had good agreement with echocardiography. Lastly, in Study V, we found that a comprehensive CMR method to diagnose and grade diastolic dysfunction showed very good agreement with echocardiography. These results suggest that novel and established CMR-based methods can diagnose pulmonary hypertension and diastolic dysfunction. Therefore, CMR may one day play an important role in the diagnostic investigation of these pathologies.List of scientific papersI. Wieslander B, Ramos JG, Ax M, Petersson J, Ugander M. (2019). Supine, prone, right and left gravitational effects on human pulmonary vascular physiology. J Cardiovasc Magn Reson. 2019 Nov 11; 21(1):69. https://doi.org/10.1186/s12968-019-0577-9 II. Ramos JG, Fyrdahl A, Wieslander B, Reiter G, Reiter U, Jin N, Maret E, Eriksson M, Caidahl K, Sörensson P, Sigfridsson A, Ugander M. Cardiovascular magnetic resonance 4D flow analysis has a higher diagnostic yield than Doppler echocardiography for detecting increased pulmonary artery pressure. BMC Medical Imaging. 2020 Mar 6; 20(1):28. https://doi.org/10.1186/s12880-020-00428-9 III. Ramos JG, Wieslander B, Fyrdahl A, Reiter G, Reiter U, Jin N, Skott V, Melin M, Sundblad P, Sigfridsson A, Ugander M. Detecting pulmonary hypertension by cardiovascular magnetic resonance four-dimensional flow analysis or echocardiography – comparison with catheterization. [Manuscript]IV. Fyrdahl A, Ramos JG, Eriksson MJ, Caidahl K, Ugander M, Sigfridsson A. Sector-wise golden-angle (SWIG) phase contrast with high temporal resolution for evaluation of left ventricular diastolic dysfunction. Magn Reson Med. 2020 Apr; 83(4):1310-1321. https://doi.org/10.1002/mrm.28018 V. Ramos JG, Fyrdahl A, Wieslander B, Reiter G, Reiter U, Jin N, Maret E, Eriksson M, Caidahl K, Sörensson P, Sigfridsson A, Ugander M. Comprehensive CMR diastolic dysfunction grading shows very good agreement compared to echocardiography. [Manuscript]</p
CHEMICAL-BOND APPROACH TO THE DIELECTRIC-CONSTANT OF SEMICONDUCTORS
No full textThe extension of the Nucho, Ramos, and Wolff method for the non-tetrahedral semiconductors was made by Brum and Ramos. This extended NRW method is applied to the elemental, group III-V, and group II-VI semiconductors and better accuracy is claimed. The ionicity for the II-VI semiconductors (zinc-blende structure) is also calculated and confirms the ionicity scale established by Phillips. Again, Coulson's definition is reconciled with that of Phillips.171241742
Estudo do isômero dextrógiro do lactato como marcador diagnóstico de infecção em recém-nascidos submetidos a tratamento cirúrgico.
No full textTrabalho de Conclusão de Curso - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Departamento de Pediatria, Curso de Medicina, Florianópolis, 200
Both doublecortin and doublecortin-like kinase play a role in cortical interneuron migration
No full textType I lissencephaly, a genetic disease characterized by disorganized cortical layers and gyral abnormalities, is associated with severe cognitive impairment and epilepsy. Two genes, LIS1 and doublecortin (DCX), have been shown to be responsible for a large proportion of cases of type I lissencephaly. Both genes encode microtubule-associated proteins that have been shown to be important for radial migration of cortical pyramidal neurons. To investigate whether DCX also plays a role in cortical interneuron migration, we inactivated DCX in the ganglionic eminence of rat embryonic day 17 brain slices using short hairpin RNA. We found that, when DCX expression was blocked, the migration of interneurons from the ganglionic eminence to the cerebral cortex was slowed but not absent, similar to what had previously been reported for radial neuronal migration. In addition, the processes of DCX-deficient migrating interneurons were more branched than their counterparts in control experiments. These effects were rescued by DCX overexpression, confirming the specificity to DCX inactivation. A similar delay in interneuron migration was observed when Doublecortin-like kinase (DCLK), a microtubule-associated protein related to DCX, was inactivated, although the morphology of the cells was not affected. The importance of these genes in interneuron migration was confirmed by our finding that the cortices of Dcx, Dclk, and Dcx/Dclk mutant mice contained a reduced number of such cells in the cortex and their distribution was different compared with wild-type controls. However, the defect was different for each group of mutant animals, suggesting that DCX and DCLK have distinct roles in cortical interneuron migration
Chemical-bond Approach To The Dielectric Constant Of Se And Te
No full textThe chemical-bond method to calculate the dielectric constant of tetrahedral semiconductors was developed by Nucho, Ramos and Wolf. The NRW method allows to express ε1 (0), via the Kramers-Kronig relation, as a function of the zeroth and first moments of ε2 (ω). Higher order contributions were neglected. We show that this approach is not appropriate for the case of Se and Te and extension of the NRW method to these non-tetrahedral semiconductors is made. © 1984.5212730O'Keefe, Navrotsky, (1981) Structure and Bonding in Crystal, , Academic Press, New YorkNucho, Ramos, Wolff, (1978) Phys. Rev., 17 B, p. 1843Nucho, Ramos, Wolff, (1978) Phys. Rev., 17 B, p. 4835Phillips, (1973) Bonds and Bands in Semiconductors, p. 40. , Academic Press, New YorkPhilipp, Ehrenreich, (1963) Phys. Rev., 129, p. 1550Bammes, Klucher, Koch, Tuomi, Anisotropy of the dielectric constants of trigonal selenium and tellurium between 3 and 30 eV (1972) Physica Status Solidi (b), 49, p. 561Van Vechten, (1969) Phys. Rev., 182, p. 891Joannopoulos, Kastner, (1975) Solid State Commun., 17, p. 221Joannopoulos, (1979) Physics of Selenium and Tellurium, p. 2. , F. Gerlack, P. Grosse, Springer Verlag, BerlinJoannopoulos, Schluter, Cohen, (1975) Phys. Rev., 11 B, p. 218
Invariant tori and Lagrange stability of pendulum-type equations
No full textAbstractIn this paper we prove that the pendulum-type equation x″ + g(t, x) = 0 possesses infinitely many invariant tori whenever g(t, x) has zero mean value on the torus T2, where g(t, x) belongs to C∞(T2). This yields the boundedness for solutions of the considered pendulum-type equation and thus leads to an answer to J. Moser's boundedness problem (1973, Ann. of Math. Stud. 77)
The charged and the spin-excitation gaps in the double-exchange model: a rigorous result
No full textWe extend a previous result of ours [G.S. Tian, Phys. Rev. B58 (1998) 7612] on the charged gap and the spin-excitation gap of the half-filled Kondo lattice model to the double-exchange model. In our original approach, this model cannot be dealt with since its localized spins have a large spin number S = 3/2. By following a construction argument due to Zener and rewriting the double-exchange Hamiltonian, we are able to overcome this difficulty and re-establish the same relation for this model.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000088659700004&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Physics, MultidisciplinarySCI(E)中国科学引文数据库(CSCD)3ARTICLE121-303
A 2-watt balanced power amplifier MMIC for Ku-band satellite communications
No full textA Ku-band power amplifier MMIC has been developed using 0.25-mum GaAs pHEMT technology. To achieve small chip size and simple drain-bias connection, a bus-bar power combiner is used. Also, balanced-power amplifier topology is used to obtain good input/ output return losses. The small-signal gain is about 15 dB and the gain variation is less than 1 dB from 12 to 17 GHz. Good input/output return losses are achieved at less than -15 dB due to the balanced topology. P-IdB of 32.6 dBm and PAE of 23.5% are achieved at 14 GHz. The effective chip area is 4.2 X 3.2 mm. Because the power amplifier is implemented using the balanced topology with the bus-bar power combiner, compact size, high output power, and good input/output return losses can be achieved simultaneously. (C) 2004 Wiley Periodicals, Inc.The author would like to thank Jeong-Ho Lee, Chung-Hwan Kim,
and Jae-Jin Lee at Teltron for their helpful discussions and encouragement.
This work was supported by KOSEF under the ERC
program through the MINT research center at Dongguk University
Flexicurity - Useful Oxymoron or Genuine Class Compromise?
No full textAuthor has checked copyrightDG 16/11/12Names JG 2012-11-1
Gesetzliche Mindestlöhne in Irland
No full textAuthor has checked copyrightDG 16/11/12Names JG 2012-11-1
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