Advanced digital SAR processing study

A highly programmable, land based, real time synthetic aperture radar (SAR) processor requiring a processed pixel rate of 2.75 MHz or more in a four look system was designed. Variations in range and azimuth compression, number of looks, range swath, range migration and SR mode were specified. Alternative range and azimuth processing algorithms were examined in conjunction with projected integrated circuit, digital architecture, and software technologies. The advaced digital SAR processor (ADSP) employs an FFT convolver algorithm for both range and azimuth processing in a parallel architecture configuration. Algorithm performace comparisons, design system design, implementation tradeoffs and the results of a supporting survey of integrated circuit and digital architecture technologies are reported. Cost tradeoffs and projections with alternate implementation plans are presented

Fourier-transform spectroscopy, direct-potential-fit, and electronic structure calculations on the entirely perturbed (4)1Π state of RbCs

We performed a high-resolution Fourier-transform spectroscopic study of the (4)1Π state of the RbCs molecule by applying two-step (4)1Π ← A1Σ+ ∼ b3Π ← X1Σ+ optical excitation followed by observation of the (4)1Π → X1Σ+ laser induced fluorescence (LIF) spectra. In many LIF progressions the collision-induced satellite rotational lines were observed thus increasing the amount of term values and allowing to estimate the Λ-doubling effect in the (4)1Π state. The Direct-Potential-Fit (DPF) of experimental term values of 777 rovibronic levels of both 85RbCs and 87RbCs isotopologues has been performed by means of the robust weighted non-linear least squares method. The PFanalysis based on adiabatic approximation and analytical Expanded Morse Oscillator potential revealed numerous regular shifts in the measured level positions. The spectroscopic studies of the (4)1Π state were supported by the electronic structure calculations including the potential energy curves of the singlet and triplet states manifold and spin-allowed transition dipole moments. The subsequent estimates of radiative lifetimes and corresponding vibronic branching ratios elucidated a dominant contribution of the (4)1Π → A ∼ b channel into the total radiative decay of the (4)1Π state. The relative intensity distributions simulated for (4)1Π → X1Σ+ LIF progressions agree well with their observed counterparts even for the profoundly shifted levels of the entirely perturbed (4)1Π state. To get an insight into the origin of the intramolecular perturbations the relevant spin-orbit and L-uncoupling electronic matrix elements were evaluatedLatvian Science Council Project No. lzp-2018/1-0020 (LZP2018/5): ”Determination of structural and dynamic properties of alkali diatomic molecules for quantum technology applications”; the University of Latvia Base Funding No A5-AZ27; Post-doctoral Grant No 1.1.1.2/16/I/001, proposal No 1.1.1.2/I/16/068; Russian Foundation for Basic Research (RFBR) Grant No. 1603-00529

Aortic valve stenotic area calculation from phase contrast cardiovascular magnetic resonance: the importance of short echo time

<p>Abstract</p> <p>Background</p> <p>Cardiovascular magnetic resonance (CMR) can potentially quantify aortic valve area (AVA) in aortic stenosis (AS) using a single-slice phase contrast (PC) acquisition at valve level: AVA = aortic flow/aortic velocity-time integral (VTI). However, CMR has been shown to underestimate aortic flow in turbulent high velocity jets, due to intra-voxel dephasing. This study investigated the effect of decreasing intra-voxel dephasing by reducing the echo time (TE) on AVA estimates in patients with AS.</p> <p>Method</p> <p>15 patients with moderate or severe AS, were studied with three different TEs (2.8 ms/2.0 ms/1.5 ms), in the main pulmonary artery (MPA), left ventricular outflow tract (LVOT) and 0 cm/1 cm/2.5 cm above the aortic valve (AoV). PC estimates of stroke volume (SV) were compared with CMR left ventricular SV measurements and PC peak velocity, VTI and AVA were compared with Doppler echocardiography. CMR estimates of AVA obtained by direct planimetry from cine acquisitions were also compared with the echoAVA.</p> <p>Results</p> <p>With a TE of 2.8 ms, the mean PC SV was similar to the ventricular SV at the MPA, LVOT and AoV_{0 cm}(by Bland-Altman analysis bias ± 1.96 SD, 1.3 ± 20.2 mL/-6.8 ± 21.9 mL/6.5 ± 50.7 mL respectively), but was significantly lower at AoV₁and AoV_2.5(-29.3 ± 31.2 mL/-21.1 ± 35.7 mL). PC peak velocity and VTI underestimated Doppler echo estimates by approximately 10% with only moderate agreement. Shortening the TE from 2.8 to 1.5 msec improved the agreement between ventricular SV and PC SV at AoV_{0 cm}(6.5 ± 50.7 mL vs 1.5 ± 37.9 mL respectively) but did not satisfactorily improve the PC SV estimate at AoV_{1 cm}and AoV_{2.5 cm}. Agreement of CMR AVA with echoAVA was improved at TE 1.5 ms (0.00 ± 0.39 cm²) versus TE 2.8 (0.11 ± 0.81 cm²). The CMR method which agreed best with echoAVA was direct planimetry (-0.03 cm²± 0.24 cm²).</p> <p>Conclusion</p> <p>Agreement of CMR AVA at the aortic valve level with echo AVA improves with a reduced TE of 1.5 ms. However, flow measurements in the aorta (AoV 1 and 2.5) are underestimated and 95% limits of agreement remain large. Further improvements or novel, more robust techniques are needed in the CMR PC technique in the assessment of AS severity in patients with moderate to severe aortic stenosis.</p

Plasma brain natriuretic peptide concentrations in patients with valvular heart disease

OBJECTIVE: Plasma brain natriuretic peptide (BNP) concentrations predict prognosis in patients with valvular heart disease (VHD), but it is unclear whether this directly relates to disease severity. We assessed the relationship between BNP and echocardiographic measures of disease severity in patients with VHD. METHODS: Plasma BNP concentrations were measured in patients with normal left ventricular (LV) systolic function and isolated VHD (mitral regurgitation (MR), n=33; aortic regurgitation (AR), n=39; aortic stenosis (AS), n=34; mitral stenosis (MS), n=30), and age-matched and sex-matched controls (n=39) immediately prior to exercise stress echocardiography. RESULTS: Compared with controls, patients with VHD had elevated plasma BNP concentrations (MR median 35 (IQR 23–52), AR 34 (22–45), AS 31 (22–60), MS 58 (34–90); controls 24 (16–33) pg/mL; p<0.01 for all). LV end diastolic volume index varied by valve lesion; (MR (mean 77±14), AR (91±28), AS (50±17), MS (43±11), controls (52±13) mL/m(2); p<0.0001). There were no associations between LV volume and BNP. Left atrial (LA) area index varied (MR (18±4 cm(2)/m(2)), AR (12±2), AS (11±3), MS (19±6), controls (11±2); p<0.0001), but correlated with plasma BNP concentrations: MR (r=0.42, p=0.02), MS (r=0.86, p<0.0001), AR (r=0.53, p=0.001), AS (r=0.52, p=0.002). Higher plasma BNP concentrations were associated with increased pulmonary artery pressure and reduced exercise capacity. Despite adverse cardiac remodelling, 81 (60%) patients had a BNP concentration within the normal range. CONCLUSIONS: Despite LV remodelling, plasma BNP concentrations are often normal in patients with VHD. Conversely, mild elevations of BNP occur with LA dilatation in the presence of normal LV. Plasma BNP concentrations should be interpreted with caution when assessing patients with VHD

HIGH-RESOLUTION FOURIER TRANSFORM SPECTROSCOPY OF LANTHANUM IN Ar DISCHARGE IN THE NEAR-INFRARED

A high-resolution spectrum of lanthanum has been recorded by a Fourier Transform spectrometer in the wavelength range from 833 nm to 1666 nm (6000 cm(-1) to 12,000 cm(-1)) using as light source a hollow cathode lamp operated with argon as the discharge carrier gas. In total, 2386 spectral lines were detected in this region, of which 555 lines could be classified as La I transitions and 10 lines as La II transitions. All La II transitions and 534 of these La I transitions were classified for the first time, and 6 of the La II transitions and 433 of the classified La I transitions appear to be new lines, which could not be found in the literature. The corresponding energy level data of classified lines are given. Additionally, 430 lines are assigned as Ar I lines and 394 as Ar II lines, of which 179 and 77, respectively, were classified for the first time. All 77 classified Ar II transitions as well as 159 of the classified Ar I transitions are new lines. Furthermore, the wavenumbers of 997 unclassified spectral lines were determined, 235 of which could be assigned as La lines, because of their hyperfine pattern. The remaining 762 lines may be either unclassified Ar lines or unresolved and unclassified La lines with only one symmetrical peak with an FWHM in the same order of magnitude as the Ar lines. The accuracy of the wavenumber for the classified lines with signal-to-noise-ratio higher than four is better than 0.006 cm(-1) which corresponds to an accuracy of 0.0004 nm at 830 nm and 0.0017 nm at 1660 nm, respectively

La-Ar Plasma Spektrumunun Yüksek Çözünürlüklü Fourier Transform Spektroskopi Yöntemi ile İncelenmesi

Yıldızlardaki kimyasal elementlerin bolluk oranlarının belirlenmesi, astrofizik &ccedil;alışmalarında teorik astrofizik modellerin oluşturulmasında b&uuml;y&uuml;k bir rol oynamaktadır. Y&uuml;ksek &ccedil;&ouml;z&uuml;n&uuml;rl&uuml;kl&uuml; yıldız spektrumlarından daha fazla bilgi sağlamak i&ccedil;in, laboratuar &ccedil;alışmalarına dayanan yeni atomik &ccedil;izgi datalarına ihtiya&ccedil; vardır. Lantan-Argon plasmasına ait 833nm- 1665nm (6000cm-1- 12000cm-1) aralığındaki yakın kırmızı altı (NIR) spektral b&ouml;lgedeki aşırı ince yapı &ccedil;izgileri, y&uuml;ksek &ccedil;&ouml;z&uuml;n&uuml;rl&uuml;kl&uuml; Fourier Transform (FT) Spektroskopisi ile incelnmiştir. Spektrum, y&uuml;ksek &ccedil;&ouml;z&uuml;n&uuml;rl&uuml;kl&uuml; BRUKER IFS 125 HR Fourier Transform Spektrometresi ile Letonya &Uuml;niversitesi, Laser Merkezi&rsquo;nde alınmıştır. Lantan elementine ait incelenen yakın kırmızı altı spektral b&ouml;lgesindeki &ccedil;izgilerin tanımlanmasında ref. [1,2,3,4] atomik dalgaboyu tablolarından yararlanıldı. Boşalım ortamında bulunan Argon elementine ait spektral &ccedil;izgiler i&ccedil;in de ref. [2,4] atomik dalgaboyu tabloları kullanıldı. Spektrumda g&ouml;r&uuml;len fakat daha &ouml;nce tanımlanmamış yeni spektral &ccedil;izgileri tanımlamak i&ccedil;in, Klasifikasyon [5] programı kullanıldı. Bu &ccedil;alışmada, NIR spektral b&ouml;lgesindeki FT spektrumunda Lantan-Argon plazmasına ait toplam 2385 spektral &ccedil;izgi g&ouml;zlendi. 753 spektral &ccedil;izginin n&ouml;tr ve iyonize Lantan elementine ait olduğu belirlendi. Yeni tanımlanan spektral &ccedil;izgilerden 520 tane La I ge&ccedil;işi, 8 tane La II ge&ccedil;iGi ilk kez sınıflandırıldı. Spektrumda, n&ouml;tr ve iyonize Argon elementine ait 857 spektral &ccedil;izginin olduğu belirlendi. Argon elementine ait bu &ccedil;izgilerden 270&rsquo;i ilk kez belirlendi ve 290 tane spektral ge&ccedil;iGin alt ve &uuml;st enerji seviyeleri verilerek ilk kez tanımlandı. Analiz sırasında NIR spektral b&ouml;lgesinde incelenen spektral &ccedil;izgilerin Doppler geniGliğinden kaynaklanan yarı geniGlikleri, spektral b&ouml;lgenin 900 nm civarında yaklaşık 2500 nm ve 1600 nm civarında ise yaklaşık 1800 MHz olduğu g&ouml;zlendi. Tanımlanan t&uuml;m sektral ge&ccedil;iGlerin ağırlık merkezlerinin doğruluğu 0.003cm-1 değeri ile belirlendi