5,730 research outputs found
Effect of nuclear transparency from the (p,2p) measurements on 6Li and 12C at 1 GeV
We studied the production of protons to the backward direction in (p,2p)
reactions on 6Li and 12C, accompanied by a proton emitted into the forward
hemisphere. The momenta of the final two protons were measured in a wide range
with the two-arm time-of-flight spectrometer. For each event we reconstructed
the mass of the intermediate off-shell particles. We have discovered a strong
narrow dip in the mass spectra of intermediate mesons at the mass of the real
pion.Comment: 24 pages,11 figure
Is Your Learned Query Optimizer Behaving As You Expect? A Machine Learning Perspective
The current boom of learned query optimizers (LQO) can be explained not only
by the general continuous improvement of deep learning (DL) methods but also by
the straightforward formulation of a query optimization problem (QOP) as a
machine learning (ML) one. The idea is often to replace dynamic programming
approaches, widespread for solving QOP, with more powerful methods such as
reinforcement learning. However, such a rapid "game change" in the field of QOP
could not pass without consequences - other parts of the ML pipeline, except
for predictive model development, have large improvement potential. For
instance, different LQOs introduce their own restrictions on training data
generation from queries, use an arbitrary train/validation approach, and
evaluate on a voluntary split of benchmark queries.
In this paper, we attempt to standardize the ML pipeline for evaluating LQOs
by introducing a new end-to-end benchmarking framework. Additionally, we guide
the reader through each data science stage in the ML pipeline and provide novel
insights from the machine learning perspective, considering the specifics of
QOP. Finally, we perform a rigorous evaluation of existing LQOs, showing that
PostgreSQL outperforms these LQOs in almost all experiments depending on the
train/test splits
New Objects in Scattering Theory with Symmetries
We consider 1D quantum scattering problem for a Hamiltonian with symmetries.
We show that the proper treatment of symmetries in the spirit of homological
algebra leads to new objects, generalizing the well known T- and K-matrices.
Homological treatment implies that old objects and new ones are be
combined in a differential. This differential arises from homotopy transfer
of induced interaction and symmetries on solutions of free
equations of motion. Therefore, old and new objects satisfy remarkable
quadratic equations. We construct an explicit example in SUSY QM on
demonstrating nontriviality of the above relation
Quality Indices Of Jaw Bone Tissue In Screening Diagnostics Of Parodontal Diseases
The objective of the work is to develop and motivate screening methods of the estimation of paradontal tissues by digital X-ray study. The used methods are X-ray digital scene with estimation of bone tissue density in program Trophy 2000, clinically anatomical parallels of bone tissue density and their qualitative indices. Parallels between qualitative indices of bones of mandibular alveolar process and bone tissue density of these areas have been revealed. It is reasonable to carry out the estimation of bone tissue density indices for revealing early stages of parodontal patholog
Rotablationsatherektomie des linken Hauptstammes bei Hochrisikopatienten: retrospektive Analyse eines monozentrischen Registers
Bei Patienten mit einer hochgradigen Stenose des Hauptstammes der linken Koronararterie ist eine operative Myokardrevaskularisation mittels aortokoronarer Bypassoperation (ACB-OP) immer noch eine bevorzugte Behandlungsmethode gemäß aktuellen Leitlinien der europäischen Gesellschaft für Kardiologie (ESC) und des American College of Cardiology/American Heart Association. In der klinischen Praxis zeigen sich oft Patienten mit hohem operativem Risiko und gleichzeitig sehr komplexer Anatomie der Läsion. Solche Patienten stellen ein therapeutisches Dilemma dar, weil einerseits die chirurgische Behandlung mit einem sehr hohen oder sogar nicht akzeptablen Risiko verbunden ist und andererseits eine interventionelle Behandlung wegen komplexer Anatomie der Läsion technisch kaum möglich ist. Die Rotablationsatherektomie (Rotationsatherektomie, Rotablation) ist eine effektive Methode, um die Koronarplaque zu modifizieren und eine PCI auch bei sehr komplexer Anatomie zu ermöglichen, zum Beispiel bei hochgradig kalzifizierten Läsionen.
In dieser Arbeit legen wir die Erfahrungen am Herzzentrum der Segeberger Kliniken GmbH mit der Rotablation des linken Hauptstammes bei 50 konsekutiven Patienten mit sehr hohem operativem Risiko und komplexen, stark kalzifizierten Läsionen des Hauptstammes dar
Accuracy comparison of several common implicit solvent models and their implementations in the context of protein-ligand binding.
In this study several commonly used implicit solvent models are compared with respect to their accuracy of estimating solvation energies of small molecules and proteins, as well as desolvation penalty in protein-ligand binding. The test set consists of 19 small proteins, 104 small molecules, and 15 protein-ligand complexes. We compared predicted hydration energies of small molecules with their experimental values; the results of the solvation and desolvation energy calculations for small molecules, proteins and protein-ligand complexes in water were also compared with Thermodynamic Integration calculations based on TIP3P water model and Amber12 force field. The following implicit solvent (water) models considered here are: PCM (Polarized Continuum Model implemented in DISOLV and MCBHSOLV programs), GB (Generalized Born method implemented in DISOLV program, S-GB, and GBNSR6 stand-alone version), COSMO (COnductor-like Screening Model implemented in the DISOLV program and the MOPAC package) and the Poisson-Boltzmann model (implemented in the APBS program). Different parameterizations of the molecules were examined: we compared MMFF94 force field, Amber12 force field and the quantum-chemical semi-empirical PM7 method implemented in the MOPAC package. For small molecules, all of the implicit solvent models tested here yield high correlation coefficients (0.87-0.93) between the calculated solvation energies and the experimental values of hydration energies. For small molecules high correlation (0.82-0.97) with the explicit solvent energies is seen as well. On the other hand, estimated protein solvation energies and protein-ligand binding desolvation energies show substantial discrepancy (up to 10kcal/mol) with the explicit solvent reference. The correlation of polar protein solvation energies and protein-ligand desolvation energies with the corresponding explicit solvent results is 0.65-0.99 and 0.76-0.96 respectively, though this difference in correlations is caused more by different parameterization and less by methods and indicates the need for further improvement of implicit solvent models parameterization. Within the same parameterization, various implicit methods give practically the same correlation with results obtained in explicit solvent model for ligands and proteins: e.g. correlation values of polar ligand solvation energies and the corresponding energies in the frame of explicit solvent were 0.953-0.966 for the APBS program, the GBNSR6 program and all models used in the DISOLV program. The DISOLV program proved to be on a par with the other used programs in the case of proteins and ligands solvation energy calculation. However, the solution of the Poisson-Boltzmann equation (APBS program) and Generalized Born method (implemented in the GBNSR6 program) proved to be the most accurate in calculating the desolvation energies of complexes
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