887 research outputs found
Design, Implementation, and Analysis of Electrical System Architecture for CubeSat to Ground Communications
CubeSats facilitate a low barrier to entry in University and Industrial space research. With the rapid, low-cost development of CubeSats, the need for a reliable and ro- bust communications subsystem becomes evident to ensure mission accomplishment. With the advent of Software Defined Radio, Old Dominion University is compelled to upgrade the rigid Legacy Hardware systems in place with inexpensive and flexible Software Defined Radio Solutions. Currently, Old Dominion University is on the cusp of conducting its first space science mission as a member organization of the Virginia Space Grant Consortium Cubesat Constellation and is manifest for launch on April 17, 2019 NASA Wallops Flight Facility. To conduct this mission, the design and construction of a 1U Nano-Satellite and the upgrade to existing ground station architecture was necessary. To relay data in a point-to-point fashion as required by the Science Mission, Old Dominion University has developed custom ground station hardware and software to communicate with its own satellite and the satellites of others. This thesis presents the salient design aspects in implementing a complete electrical system architecture for a 1U spacecraft and the upgrades required in the Ground Station Architecture to support the required demodulation and decoding of a 9600 baud GMSK signal from a model of the deployed satellite necessary to conduct a true science research mission as part of a University Satellite Constellation. The demodulating signal processing steps are designed in GNU Radio Companion and deals with parts of the AX.25 data link layer protocol. Additionally, analysis shall be presented to highlight the design choices made for both the spacecraft and the ground station and will demonstrate various system parameters and characteristics of interest based on the Orbital Simulation results obtained from Systems Toolkit (STK). Finally, results of the architecture design shall be reported on the system by measuring Communications Link Performance benchmarks such as Bit-Error-Rates (BER) and Signal-To-Noise Ratios (SNR)
Form factor in K+ --> pi+ pi0 gamma: interference versus direct emission
We analyze the effect of a form factor in the magnetic contribution to K+ -->
pi+ pi0 gamma. We emphasize how this can show up experimentally: in particular
we try to explore the difference between a possible interference contribution
and a form factor in the magnetic part. The form factor used for K+ --> pi+ pi0
gamma is analogous to the one for KL --> pi+ pi- gamma, experimentally well
established.Comment: 9 pages revtex, 10 eps figures; improved presentation of theoretical
and experimental status; refs. adde
The Rapid Measurement of Benzodiazepines in a Milk-Based Alcoholic Beverage Using QuEChERS Extraction and GCâMS Analysis
none5noBenzodiazepines (BDZs) are widely used as tranquilizers and antidepressive
drugs in common clinical practice. However, their ready
availability and their synergistic effects with alcohol make them
attractive for criminal intentions. To prove criminal action for legal
reasons, it is often necessary to analyze beverage residues from a
crime scene. Milk-based alcoholic drinks (whiskey creams) are gaining
popularity due to their lower alcohol content pleasant taste.
However, the complexity of this sample, containing proteins and
fatty acids, can mask the presence of drugs or other substances in
standard analysis methods. These characteristics make whiskey
creams highly suitable for illicit purposes. In this study, eight BDZs,
including diazepam, chlordiazepoxide, clobazam, flunitrazepam, bromazepam,
flurazepam, nitrazepam and clonazepam, were extracted
from whiskey cream using the Quick, Easy, Cheap, Effective,
Rugged and Safe (QuEChERS) method and analyzed using GCâMS.
The QuEChERS protocol can efficiently separate most of the matrix
from the target compounds while maintaining acceptable recoveries.
The presented method is simple and rapid and has been validated in
terms of precision, accuracy and recoveries. Limits of detection and
limits of quantitationwere in the range of 0.02â0.1 and 0.1â0.5 mg/mL,
respectively. Whiskey cream beverages, fortified with commercial
drugs at 20 mg/mL, were extracted and analyzed demonstrating the
applicability of the method in forensic analysis.openFamiglini, G.; Capriotti, F.; Palma, P.; Termopoli, V.; Cappiello, A.Famiglini, Giorgio; Capriotti, Fabiana; Palma, Pierangela; Termopoli, Veronica; Cappiello, Achill
Generating Functional for Strong and Nonleptonic Weak Interactions
The generating functional for Green functions of quark currents is given in
closed form to next-to-leading order in the low-energy expansion for chiral
SU(3), including one-loop amplitudes with up to three meson propagators. Matrix
elements and form factors for strong and nonleptonic weak processes with at
most six external states can be extracted from this functional by performing
three-dimensional flavour traces. To implement this procedure, a Mathematica
program is provided that evaluates amplitudes with at most six external mesons,
photons (real or virtual) and virtual W (semileptonic form factors). The
program is illustrated with several examples that can be compared with existing
calculations.Comment: 26 pages; references added, comparison with other programs added,
small changes in the text, version to appear in JHE
K^+ -> pi^+pi^0e^+e^-: a novel short-distance probe
We study the decay K^+ -> pi^+ pi^0 e^+ e^-, currently under analysis by the
NA62 Collaboration at CERN. In particular, we provide a detailed analysis of
the Dalitz plot for the long-distance, gamma^*-mediated, contributions
(Bremsstrahlung, direct emission and its interference). We also examine a set
of asymmetries to isolate genuine short-distance effects. While we show that
charge asymmetries are not required to test short distances, they provide the
best environment for its detection. This constitutes by itself a strong
motivation for NA62 to study K^- decays in the future. We therefore provide a
detailed study of different charge asymmetries and the corresponding estimated
signals. Whenever possible, we make contact with the related processes K^+ ->
pi^+ pi^0 gamma and K_L -> pi^+ pi^- e^+ e^- and discuss the advantages of K^+
-> pi^+ pi^0 e^+ e^- over them.Comment: 25 pages, 6 figure
Prompt and accurate diagnosis of ventricular arrhythmias with a novel index based on phase space reconstruction of ECG
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Aim
To develop a statistical index based on the phase space reconstruction (PSR) of the electrocardiogram (ECG) for the accurate and timely diagnosis of ventricular tachycardia (VT) and ventricular fibrillation (VF).
Methods
Thirty-two ECGs with sinus rhythm (SR) and 32 ECGs with VT/VF were analyzed using the PSR technique. Firstly, the method of time delay embedding were employed with the insertion of delay âÏâ in the original time-series X(t), which produces the Y(t) = X(t â Ï). Afterwards, a PSR diagram was reconstructed by plotting Y(t) against X(t). The method of box counting was applied to analyze the behavior of the PSR trajectories. Measures as mean (ÎŒ), standard deviation (Ï) and coefficient of variation (CV = Ï/ÎŒ), kurtosis (ÎČ) for the box counting of PSR diagrams were reported.
Results
During SR, CV was always 0.05. A similar pattern was observed with ÎČ, where < 6 was considered as the cut-off point between SR and VT/VF. Therefore, the upper threshold for SR was considered CVth = 0.05 and ÎČth < 6. For optimisation of the accuracy, a new index (J) was proposed:
J=wCVCVth+1âwÎČÎČth.
During SR the upper limit of J was the value of 1. Furthermore CV, ÎČ and J crossed the cut-off point timely before the onset of arrhythmia (average time: 4 min 31 s; SD: 2 min 30 s); allowing sufficient time for preventive therapy.
Conclusion
The J index improved ECG utility for arrhythmia monitoring and detection utility, allowing the prompt and accurate diagnosis of ventricular arrhythmias
A holographic approach to low-energy weak interactions of hadrons
We apply the double-trace formalism to incorporate nonleptonic weak
interactions of hadrons into holographic models of the strong interactions. We
focus our attention upon nonleptonic kaon decays. By working with
a Yang-Mills--Chern-Simons 5-dimensional action, we explicitly show how, at low
energies, one recovers the weak chiral Lagrangian for both the
anomalous and nonanomalous sectors. We provide definite predictions for the low
energy coefficients in terms of the AdS metric and argue that the double-trace
formalism is a 5-dimensional avatar of the Weak Deformation Model introduced
long ago by Ecker et al. As a significant phenomenological application, we
reassess the decays in the light of the holographic model. Previous
models found a fine-tuned cancellation of resonance exchange in these decays,
which was both conceptually puzzling and quantitatively in disagreement with
experimental results. The holographic model we build is an illustrative
counterexample showing that the cancellation encountered in the literature is
not generic but a model-dependent statement and that agreement with experiment
can be obtained.Comment: 20 page
Vector-meson contributions do not explain the rate and spectrum in K_L -> pi0 gamma gamma
We analyze the recent NA48 data for the reaction K_L -> pi0 gamma gamma with
and without the assumption of vector meson dominance (VMD). We find that the
data is well described by a three-parameter expression inspired by O(p^6)
chiral perturbation theory. We also find that it is impossible to fit the shape
of the decay distribution and the overall rate simultaneously if one imposes
the VMD constraints on the three parameters. We comment on the different fits
and their implications for the CP-conserving component of the decay K_L -> pi0
e+ e-.Comment: Version accepted for publication on Phys. Rev. D. 19 pages, LaTeX, 8
figures, uses epsf.st
A statistical index for early diagnosis of ventricular arrhythmia from the trend analysis of ECG phase-portraits
This is the author accepted manuscript. The final version is available from IOP Publishing via the DOI in this record.In this paper, we propose a novel statistical index for the early diagnosis of ventricular arrhythmia (VA) using the time delay phase-space reconstruction (PSR) technique, from the electrocardiogram (ECG) signal. Patients with two classes of fatal VA-with preceding ventricular premature beats (VPBs) and with no VPBs-have been analysed using extensive simulations. Three subclasses of VA with VPBs viz. ventricular tachycardia (VT), ventricular fibrillation (VF) and VT followed by VF are analyzed using the proposed technique. Measures of descriptive statistics like mean (”), standard deviation (Ï), coefficient of variation (CV = Ï/”), skewness (Îł) and kurtosis (ÎČ) in phase-space diagrams are studied for a sliding window of 10 beats of the ECG signal using the box-counting technique. Subsequently, a hybrid prediction index which is composed of a weighted sum of CV and kurtosis has been proposed for predicting the impending arrhythmia before its actual occurrence. The early diagnosis involves crossing the upper bound of a hybrid index which is capable of predicting an impending arrhythmia 356 ECG beats, on average (with 192 beats standard deviation) before its onset when tested with 32 VA patients (both with and without VPBs). The early diagnosis result is also verified using a leave one out cross-validation (LOOCV) scheme with 96.88% sensitivity, 100% specificity and 98.44% accuracy.This work was supported by the E.U. ARTEMIS Joint Undertaking under the Cyclic and person-centric Health management: Integrated appRoach for hOme, mobile and clinical eNvironmentsâ(CHIRON) Project, Grant Agreement # 2009-1-100228
Role of Scalar Meson Resonances in $K_{L}^{0} \rightarrow \pi^{0} \gamma \gamma Decay
Corrections to decay induced by
scalar meson exchange are studied within chiral perturbation theory. In spite
of bad knowledge of scalar-mesons parameters, the calculated branching ratio
can be changed by a few percent.Comment: 18 pages of text, 2 figures (available upon request); preprint
IJS-TP-16-94 , TUM-T31-63-94
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