917 resultados para Rydberg-Ritz combination principle


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A new ''Ritz'' program has been used for revising and expanding the assignment of the Fourier transform infrared and far-infrared spectrum of CH3OH. This program evaluates the energy levels involved in the assigned transitions by the Rydberg-Ritz combination principle and can tackle such perturbations as Fermi-type resonances or Coriolis interactions. Up to now this program has evaluated the energies of 2768 levels belonging to A-type symmetry and 4133 levels belonging to E-type symmetry of CH3OH. Here we present the assignment of almost 9600 lines between 350 and 950 cm(-1). The Taylor expansion coefficients for evaluating the energies of the levels involved in the transitions are also given. All of the lines presented in this paper correspond to transitions involving torsionally excited levels within the ground vibrational state. (C) 1995 Academic Press, Inc.

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We have revisited the assignments of the far-infrared laser lines emitted by (CH3OH)-C-13 by comparing the laser systems to a high resolution Fourier transform absorption spectrum of (CH3OH)-C-13. The absorption spectrum was analyzed by means of the ''Ritz'' program, which calculates the energy level values directly from the Rydberg-Ritz combination principle. We report new assignments for 11 FIR laser transitions, 17 frequency predictions for new possible laser lines, and we confirm 11 previous assignments. (C) 1996 Academic Press, Inc.

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We have investigated the high-resolution Fourier transform spectrum of the C-O stretching fundamental band of CD3OH in order to assign far-infrared (FIR) laser transitions. The absorption spectrum was analyzed by means of the ''Ritz'' program, which calculates the energy level values directly from the Rydberg-Ritz combination principle. We have also used the ''LaseRitz'' program to facilitate the assignment of the FIR laser lines. As a consequence we could determine 12 new assignments, confirming 4 previously proposed ones and predicting new FIR laser emissions. (C) 1997 Academic Press.

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The Ritz computer program, developed for facilitating the assignment of molecular Fourier transform absorption spectra and described in a previous work, determines the energy level values involved in the assigned transitions by the Rydberg-Ritz combination principle. Combining the data obtained from the analyses of high-resolution infrared (IR) and far-infrared (FIR) spectra, it is possible to predict possible FIR laser emissions of molecules. In the present work we have applied this method to the common isotopomer methanol, 12CH3 16OH, and obtained 14 proposed assignments for previously unassigned FIR laser lines. We also predict 15 possible new FIR laser emissions. For the first time, an assignment involving a four-level laser system with collisional population transfer to a slightly higher energy level is reported. © 1998 Academic Press.

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Diese Arbeit beschreibt eine wesentliche Weiterentwicklung des Titan:Saphir-Lasersystems der Arbeitsgruppe LARISSA am Institut für Physik der Johannes Gutenberg-Universität Mainz und dessen Anwendung im Bereich der Resonanzionisationsspektroskopie. Die Entwicklungsarbeiten am Lasersystem umfassten drei Aspekte: die Erhöhung der Ausgangsleistung der vorhandenen Titan:Saphir-Laser um einen Faktor zwei, um damit für den vorgesehenen Einsatz an resonanten Laserionenquellen an ISOL-Einrichtungen optimale Voraussetzungen zu schaffen. Des Weiteren wurden zwei spezielle angepasste Titan:Saphir-Laser entwickelt: Das Lasersystem wurde damit um einen von 700 nm - 950 nm kontinuierlich abstimmbaren Titan:Saphir-Laser sowie einen geseedeten Titan:Saphir-Laser mit einer Linienbreite von nur 20 MHz (im Vergleich zu 3 GHz der konventionellen Laser) erweitert. Die Leistungsfähigkeit des neuen Lasersystems wurde durch Resonanzionisationsspektroskopie hochangeregter atomarer Zustände in Gold und Technetium demonstriert. Aus den gemessenen Energielagen konnte über die Rydberg-Ritz-Formel das Ionisationspotential von Gold bestätigt werden und das von Technetium erstmals mit hoher Präzision bestimmt werden. Mit dem geseedeten Titan:Saphir-Laser wurde dopplerfreie Zwei-Photonen-Spektroskopie innerhalb eines heißen Ofens demonstriert. Bei spektroskopischen Untersuchungen mit dieser Methode an Siliziumisotopen konnte sowohl die Hyperfeinstruktur als auch die Isotopieverschiebung bei einer Breite der Resonanzen von etwa 90 MHz klar aufgelöst werden.

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OBJECT: To study a scan protocol for coronary magnetic resonance angiography based on multiple breath-holds featuring 1D motion compensation and to compare the resulting image quality to a navigator-gated free-breathing acquisition. Image reconstruction was performed using L1 regularized iterative SENSE. MATERIALS AND METHODS: The effects of respiratory motion on the Cartesian sampling scheme were minimized by performing data acquisition in multiple breath-holds. During the scan, repetitive readouts through a k-space center were used to detect and correct the respiratory displacement of the heart by exploiting the self-navigation principle in image reconstruction. In vivo experiments were performed in nine healthy volunteers and the resulting image quality was compared to a navigator-gated reference in terms of vessel length and sharpness. RESULTS: Acquisition in breath-hold is an effective method to reduce the scan time by more than 30 % compared to the navigator-gated reference. Although an equivalent mean image quality with respect to the reference was achieved with the proposed method, the 1D motion compensation did not work equally well in all cases. CONCLUSION: In general, the image quality scaled with the robustness of the motion compensation. Nevertheless, the featured setup provides a positive basis for future extension with more advanced motion compensation methods.

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TERMINOLOGY AND PRINCIPLES OF COMBINING ANTIPSYCHOTICS WITH A SECOND MEDICATION: The term "combination" includes virtually all the ways in which one medication may be added to another. The other commonly used terms are "augmentation" which implies an additive effect from adding a second medicine to that obtained from prescribing a first, an "add on" which implies adding on to existing, possibly effective treatment which, for one reason or another, cannot or should not be stopped. The issues that arise in all potential indications are: a) how long it is reasonable to wait to prove insufficiency of response to monotherapy; b) by what criteria that response should be defined; c) how optimal is the dose of the first monotherapy and, therefore, how confident can one be that its lack of effect is due to a truly inadequate response? Before one considers combination treatment, one or more of the following criteria should be met; a) monotherapy has been only partially effective on core symptoms; b) monotherapy has been effective on some concurrent symptoms but not others, for which a further medicine is believed to be required; c) a particular combination might be indicated de novo in some indications; d) The combination could improve tolerability because two compounds may be employed below their individual dose thresholds for side effects. Regulators have been concerned primarily with a and, in principle at least, c above. In clinical practice, the use of combination treatment reflects the often unsatisfactory outcome of treatment with single agents. ANTIPSYCHOTICS IN MANIA: There is good evidence that most antipsychotics tested show efficacy in acute mania when added to lithium or valproate for patients showing no or a partial response to lithium or valproate alone. Conventional 2-armed trial designs could benefit from a third antipsychotic monotherapy arm. In the long term treatment of bipolar disorder, in patients responding acutely to the addition of quetiapine to lithium or valproate, this combination reduces the subsequent risk of relapse to depression, mania or mixed states compared to monotherapy with lithium or valproate. Comparable data is not available for combination with other antipsychotics. ANTIPSYCHOTICS IN MAJOR DEPRESSION: Some atypical antipsychotics have been shown to induce remission when added to an antidepressant (usually a SSRI or SNRI) in unipolar patients in a major depressive episode unresponsive to the antidepressant monotherapy. Refractoriness is defined as at least 6 weeks without meeting an adequate pre-defined treatment response. Long term data is not yet available to support continuing efficacy. SCHIZOPHRENIA: There is only limited evidence to support the combination of two or more antipsychotics in schizophrenia. Any monotherapy should be given at the maximal tolerated dose and at least two antipsychotics of different action/tolerability and clozapine should be given as a monotherapy before a combination is considered. The addition of a high potency D2/3 antagonist to a low potency antagonist like clozapine or quetiapine is the logical combination to treat positive symptoms, although further evidence from well conducted clinical trials is needed. Other mechanisms of action than D2/3 blockade, and hence other combinations might be more relevant for negative, cognitive or affective symptoms. OBSESSIVE-COMPULSIVE DISORDER: SSRI monotherapy has moderate overall average benefit in OCD and can take as long as 3 months for benefit to be decided. Antipsychotic addition may be considered in OCD with tic disorder and in refractory OCD. For OCD with poor insight (OCD with "psychotic features"), treatment of choice should be medium to high dose of SSRI, and only in refractory cases, augmentation with antipsychotics might be considered. Augmentation with haloperidol and risperidone was found to be effective (symptom reduction of more than 35%) for patients with tics. For refractory OCD, there is data suggesting a specific role for haloperidol and risperidone as well, and some data with regard to potential therapeutic benefit with olanzapine and quetiapine. ANTIPSYCHOTICS AND ADVERSE EFFECTS IN SEVERE MENTAL ILLNESS: Cardio-metabolic risk in patients with severe mental illness and especially when treated with antipsychotic agents are now much better recognized and efforts to ensure improved physical health screening and prevention are becoming established.

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Introduction: Trastuzumab (T) is a cornerstone in the treatment of patients with HER2-overexpressing advanced breast cancer and development of resistance to T is a major therapeutic problem. HER-2 is part of a highly interactive signaling network that may impair efficacy of endocrine therapy. A sequential treatment design was chosen in this trial to ensure complete resistance to single agent therapy before receiving both a non-steroidal aromatase inhibitor (AI) and T. Any kind of clinical activity with combined treatment of AI and T after progression of single agent treatments could indicate restoration of sensitivity as a consequence of cross-talking and networking between both pathways. Methods: Key eligibility criteria included postmenopausal patients (pts.) with advanced, measurable, HER-2 positive (assessed by FISH, ratio (≥2)), HR positive disease and progression on prior treatment with a non-steroidal AI, e.g. letrozole or anastrozole, either in an adjuvant or advanced setting. Pts. received standard dose T monotherapy either weekly or three-weekly in step 1 and upon disease progression, continued T in combination with letrozole in step 2. The primary endpoint was clinical benefit response (CBR: CR, PR or SD for at least 24 weeks (+/- 1 week) according to RECIST) in step 2. Results: Thirteen pts. were enrolled in five centers in Switzerland. In step 1, six pts. (46%) achieved CBR. Median time to progression (TTP) was 161 days (Range: 50 - 627). Based on data collected until the end of May 2010, CBR was observed in seven out of the eleven evaluable pts. (64%) in step 2, including one pt. with partial response. Four of the seven pts. within step 2 that achieved CBR also had CBR in step 1. Seven out of eleven pts. have documented tumor progression during step 2 treatment. Median TTP for all eleven pts. was 184 days (range 61 - 471). Mean time on study treatment (TTP in step 1 plus TTP in step 2) for pts. reaching step 2 was 380 days (range 174 - 864). Adverse events were generally mild. Conclusion: Results of this proof-of-principle trial suggest that complete resistance to both AI and T can be overcome in a proportion of pts. by combined treatment of AI and T, as all pts. served as their own control. Our results appear promising for a new treatment strategy which offers a chemotherapy-free and well-tolerated option for at least a subset of the pts. with HR positive, HER-2 positive breast cancer. Further trials will need to corroborate this finding.

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Relativistic density functional theory is widely applied in molecular calculations with heavy atoms, where relativistic and correlation effects are on the same footing. Variational stability of the Dirac Hamiltonian is a very important field of research from the beginning of relativistic molecular calculations on, among efforts for accuracy, efficiency, and density functional formulation, etc. Approximations of one- or two-component methods and searching for suitable basis sets are two major means for good projection power against the negative continuum. The minimax two-component spinor linear combination of atomic orbitals (LCAO) is applied in the present work for both light and super-heavy one-electron systems, providing good approximations in the whole energy spectrum, being close to the benchmark minimax finite element method (FEM) values and without spurious and contaminated states, in contrast to the presence of these artifacts in the traditional four-component spinor LCAO. The variational stability assures that minimax LCAO is bounded from below. New balanced basis sets, kinetic and potential defect balanced (TVDB), following the minimax idea, are applied with the Dirac Hamiltonian. Its performance in the same super-heavy one-electron quasi-molecules shows also very good projection capability against variational collapse, as the minimax LCAO is taken as the best projection to compare with. The TVDB method has twice as many basis coefficients as four-component spinor LCAO, which becomes now linear and overcomes the disadvantage of great time-consumption in the minimax method. The calculation with both the TVDB method and the traditional LCAO method for the dimers with elements in group 11 of the periodic table investigates their difference. New bigger basis sets are constructed than in previous research, achieving high accuracy within the functionals involved. Their difference in total energy is much smaller than the basis incompleteness error, showing that the traditional four-spinor LCAO keeps enough projection power from the numerical atomic orbitals and is suitable in research on relativistic quantum chemistry. In scattering investigations for the same comparison purpose, the failure of the traditional LCAO method of providing a stable spectrum with increasing size of basis sets is contrasted to the TVDB method, which contains no spurious states already without pre-orthogonalization of basis sets. Keeping the same conditions including the accuracy of matrix elements shows that the variational instability prevails over the linear dependence of the basis sets. The success of the TVDB method manifests its capability not only in relativistic quantum chemistry but also for scattering and under the influence of strong external electronic and magnetic fields. The good accuracy in total energy with large basis sets and the good projection property encourage wider research on different molecules, with better functionals, and on small effects.

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Parkinson’s disease (PD) is an increasing neurological disorder in an aging society. The motor and non-motor symptoms of PD advance with the disease progression and occur in varying frequency and duration. In order to affirm the full extent of a patient’s condition, repeated assessments are necessary to adjust medical prescription. In clinical studies, symptoms are assessed using the unified Parkinson’s disease rating scale (UPDRS). On one hand, the subjective rating using UPDRS relies on clinical expertise. On the other hand, it requires the physical presence of patients in clinics which implies high logistical costs. Another limitation of clinical assessment is that the observation in hospital may not accurately represent a patient’s situation at home. For such reasons, the practical frequency of tracking PD symptoms may under-represent the true time scale of PD fluctuations and may result in an overall inaccurate assessment. Current technologies for at-home PD treatment are based on data-driven approaches for which the interpretation and reproduction of results are problematic.  The overall objective of this thesis is to develop and evaluate unobtrusive computer methods for enabling remote monitoring of patients with PD. It investigates first-principle data-driven model based novel signal and image processing techniques for extraction of clinically useful information from audio recordings of speech (in texts read aloud) and video recordings of gait and finger-tapping motor examinations. The aim is to map between PD symptoms severities estimated using novel computer methods and the clinical ratings based on UPDRS part-III (motor examination). A web-based test battery system consisting of self-assessment of symptoms and motor function tests was previously constructed for a touch screen mobile device. A comprehensive speech framework has been developed for this device to analyze text-dependent running speech by: (1) extracting novel signal features that are able to represent PD deficits in each individual component of the speech system, (2) mapping between clinical ratings and feature estimates of speech symptom severity, and (3) classifying between UPDRS part-III severity levels using speech features and statistical machine learning tools. A novel speech processing method called cepstral separation difference showed stronger ability to classify between speech symptom severities as compared to existing features of PD speech. In the case of finger tapping, the recorded videos of rapid finger tapping examination were processed using a novel computer-vision (CV) algorithm that extracts symptom information from video-based tapping signals using motion analysis of the index-finger which incorporates a face detection module for signal calibration. This algorithm was able to discriminate between UPDRS part III severity levels of finger tapping with high classification rates. Further analysis was performed on novel CV based gait features constructed using a standard human model to discriminate between a healthy gait and a Parkinsonian gait. The findings of this study suggest that the symptom severity levels in PD can be discriminated with high accuracies by involving a combination of first-principle (features) and data-driven (classification) approaches. The processing of audio and video recordings on one hand allows remote monitoring of speech, gait and finger-tapping examinations by the clinical staff. On the other hand, the first-principles approach eases the understanding of symptom estimates for clinicians. We have demonstrated that the selected features of speech, gait and finger tapping were able to discriminate between symptom severity levels, as well as, between healthy controls and PD patients with high classification rates. The findings support suitability of these methods to be used as decision support tools in the context of PD assessment.

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The limitations of diagnostic echo ultrasound have motivated research into novel modalities that complement ultrasound in a multimodal device. One promising candidate is speed of sound imaging, which has been found to reveal structural changes in diseased tissue. Transmission ultrasound tomography shows speed of sound spatially resolved, but is limited to the acoustically transparent breast. We present a novel method by which speed-of-sound imaging is possible using classic pulse-echo equipment, facilitating new clinical applications and the combination with state-of-the art diagnostic ultrasound. Pulse-echo images are reconstructed while scanning the tissue under various angles using transmit beam steering. Differences in average sound speed along different transmit directions are reflected in the local echo phase, which allows a 2-D reconstruction of the sound speed. In the present proof-of-principle study, we describe a contrast resolution of 0.6% of average sound speed and a spatial resolution of 1 mm (laterally) × 3 mm (axially), suitable for diagnostic applications.

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Connected logic gates can be operated on the levels of one molecule by making use of the special properties of high Rydberg states. Explicit experimental results for the NO molecule are provided as an example. A number of other options, including that of several gates concatenated so as to operate as a full adder, are discussed. Specific properties of high Rydberg states that are used are: their autoionization is delayed so that they can be distinguished from direct multiphoton ionization, during their long life such states also can decay by energy transfer to the molecular core in a way that can be controlled by the judicious application of very weak external electrical fields, and the Rydberg states can be detected by the application of an ionizing electrical field. The combination of two (or three) color photons with and without external weak fields allows the construction of quite elaborate logic circuit diagrams and shows that taking advantage of the different intramolecular dynamics of levels that differ by their excitation enables the compounding of logic operations on one molecular frame.

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The subject of investigation of the present research is the use of smart hydrogels with fibre optic sensor technology. The aim was to develop a costeffective sensor platform for the detection of water in hydrocarbon media, and of dissolved inorganic analytes, namely potassium, calcium and aluminium. The fibre optic sensors in this work depend upon the use of hydrogels to either entrap chemotropic agents or to respond to external environmental changes, by changing their inherent properties, such as refractive index (RI). A review of current fibre optic technology for sensing outlined that the main principles utilised are either the measurement of signal loss or a change in wavelength of the light transmitted through the system. The signal loss principle relies on changing the conditions required for total internal reflection to occur. Hydrogels are cross-linked polymer networks that swell but do not dissolve in aqueous environments. Smart hydrogels are synthetic materials that exhibit additional properties to those inherent in their structure. In order to control the non-inherent properties, the hydrogels were fabricated with the addition of chemotropic agents. For the detection of water, hydrogels of low refractive index were synthesized using fluorinated monomers. Sulfonated monomers were used for their extreme hydrophilicity as a means of water sensing through an RI change. To enhance the sensing capability of the hydrogel, chemotropic agents, such as pH indicators and cobalt salts, were used. The system comprises of the smart hydrogel coated onto an exposed section of the fibre optic core, connected to the interrogation system measuring the difference in the signal. Information obtained was analysed using a purpose designed software. The developed sensor platform showed that an increase in the target species caused an increase in the signal lost from the sensor system, allowing for a detection of the target species. The system has potential applications in areas such as clinical point of care, water detection in fuels and the detection of dissolved ions in the water industry.

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Binocular combination for first-order (luminancedefined) stimuli has been widely studied, but we know rather little about this binocular process for spatial modulations of contrast (second-order stimuli). We used phase-matching and amplitude-matching tasks to assess binocular combination of second-order phase and modulation depth simultaneously. With fixed modulation in one eye, we found that binocularly perceived phase was shifted, and perceived amplitude increased almost linearly as modulation depth in the other eye increased. At larger disparities, the phase shift was larger and the amplitude change was smaller. The degree of interocular correlation of the carriers had no influence. These results can be explained by an initial extraction of the contrast envelopes before binocular combination (consistent with the lack of dependence on carrier correlation) followed by a weighted linear summation of second-order modulations in which the weights (gains) for each eye are driven by the first-order carrier contrasts as previously found for first-order binocular combination. Perceived modulation depth fell markedly with increasing phase disparity unlike previous findings that perceived first-order contrast was almost independent of phase disparity. We present a simple revision to a widely used interocular gain-control theory that unifies first- and second-order binocular summation with a single principle-contrast-weighted summation-and we further elaborate the model for first-order combination. Conclusion: Second-order combination is controlled by first-order contrast.

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2010 Mathematics Subject Classification: 94A17.