Initial experience with using frameless image-guided radiosurgery for the treatment of brain metastases

Aim : Recent technologic advances have led to the development of frameless radiosurgery. We report our initial results using frameless image-guided radiosurgery for the management of brain metastases. Methods: Over a 2-year period, 16 patients harboring 28 lesions were treated in our institution. 12 of 16 patients were treated in a single fraction, but 4 patients were treated using fractioned stereotactic radiotherapy in 3–5 fractions. The maximum target diameter, as determined by T1 — weighted contrast — enhanced magnetic resonance imaging were < 4 cm in all patients. 8 patients (50%) received WBRT (3 Gy in 10 fractions to a total dose of 30 Gy) prior to stereotactic radiosurgery, and were treated with SRS for either lesion progression or new lesions. The total treatment volume for each patient was the sum of the treatment volumes for all treated metastases. The median total treatment volume was 18.63 cm3 (range 1,85–47.03 cm3). Results: Median overall survival time of entire group were 10 months (95% confidence interval 7.470–12.530 months). Of the 3 (11.11%) lesions that showed complete response, all were associated with breast cancer. Partial response was seen in 8 (29.62%) cases. Stable disease was seen in 13 (48.14%) cases, but 3 (11.11%) cases showed progression of disease. Conclusion: Further studies are needed to to match the treatment results with other available modalities to optimize and individualize care of patients with brain metastases

DEVELOPMENT OF LIQUID CRYSTAL LAYER THICKNESS AND REFRACTIVE INDEX MEASUREMENT METHODS FOR SCATTERING TYPE LIQUID CRYSTAL DISPLAYS

The research has been supported by ERDF No.1.1.1.1/19/A/120 “Improvement of Electro-Optical Characteristics of Liquid Crystal Shutters”.We report the measuring method of scattering type display liquid crystal layer thickness based on capacitance values suitable for inline production process control. The method is selected for its effectiveness and simplicity over spectroscopic methods as conventional methods for scattering type displays are not applicable. During the method approbation process, a novel diffuser liquid crystal mixture refractive index was determined based on liquid crystal layer thickness measurement data. © 2022 Sciendo. All rights reserved. --//-- This is an open access article Ozols A., Mozolevskis G., Zalubovskis R., Rutkis M. DEVELOPMENT OF LIQUID CRYSTAL LAYER THICKNESS AND REFRACTIVE INDEX MEASUREMENT METHODS FOR SCATTERING TYPE LIQUID CRYSTAL DISPLAYS (2022) Latvian Journal of Physics and Technical Sciences, 59 (4), pp. 25 - 35, DOI: 10.2478/lpts-2022-0031 published under the CC BY-NC-ND 4.0 licence.ERDF No.1.1.1.1/19/A/120; Institute of Solid-State Physics, University of Latvia has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-Teaming Phase 2 under grant agreement No. 739508, project CAMART2.

Quantum rejection sampling

Rejection sampling is a well-known method to sample from a target distribution, given the ability to sample from a given distribution. The method has been first formalized by von Neumann (1951) and has many applications in classical computing. We define a quantum analogue of rejection sampling: given a black box producing a coherent superposition of (possibly unknown) quantum states with some amplitudes, the problem is to prepare a coherent superposition of the same states, albeit with different target amplitudes. The main result of this paper is a tight characterization of the query complexity of this quantum state generation problem. We exhibit an algorithm, which we call quantum rejection sampling, and analyze its cost using semidefinite programming. Our proof of a matching lower bound is based on the automorphism principle which allows to symmetrize any algorithm over the automorphism group of the problem. Our main technical innovation is an extension of the automorphism principle to continuous groups that arise for quantum state generation problems where the oracle encodes unknown quantum states, instead of just classical data. Furthermore, we illustrate how quantum rejection sampling may be used as a primitive in designing quantum algorithms, by providing three different applications. We first show that it was implicitly used in the quantum algorithm for linear systems of equations by Harrow, Hassidim and Lloyd. Secondly, we show that it can be used to speed up the main step in the quantum Metropolis sampling algorithm by Temme et al.. Finally, we derive a new quantum algorithm for the hidden shift problem of an arbitrary Boolean function and relate its query complexity to "water-filling" of the Fourier spectrum.Comment: 19 pages, 5 figures, minor changes and a more compact style (to appear in proceedings of ITCS 2012

Focusing of a tabletop soft-x-ray laser beam and laser ablation

Includes bibliographical references (page 1716).We focused the beam of a high-repetition-rate capillary-discharge tabletop laser operating at a wavelength of 46.9 nm, using a spherical Si/Sc multilayer mirror. The energy densities significantly exceeded the thresholds for the ablation of metals. Single-shot laser ablation patterns were used in combination with ray-tracing computations to characterize the focused beam. The radiation intensity within the 2-μm-diameter central region of the focal spot was estimated to be ≈1011 W/cm2, with a corresponding energy density of ~100 J/cm2

Actividad física, ejercicio físico y adulto mayor

Se ha comprobado que la actividad física y el ejercicio mejoran la calidad de vida de las personas mayores. Las investigaciones han encontrado progresos en el plano físico, emocional y social. Una de las organizaciones que está promoviendo estilos de vida saludables es la Organización Mundial de la Salud, que ha enfocado su atención en todas las etapas de la vida: desde la niñez hasta la edad adulta mayor

Distributions attaining secret key at a rate of the conditional mutual information

© International Association for Cryptologic Research 2015. In this paper we consider the problem of extracting secret key from an eavesdropped source pXY Z at a rate given by the conditional mutual information. We investigate this question under three different scenarios: (i) Alice (X) and Bob (Y) are unable to communicate but share common randomness with the eavesdropper Eve (Z), (ii) Alice and Bob are allowed one-way public communication, and (iii) Alice and Bob are allowed two-way public communication. Distributions having a key rate of the conditional mutual information are precisely those in which a “helping” Eve offers Alice and Bob no greater advantage for obtaining secret key than a fully adversarial one. For each of the above scenarios, strong necessary conditions are derived on the structure of distributions attaining a secret key rate of I(X: Y |Z). In obtaining our results, we completely solve the problem of secret key distillation under scenario (i) and identify H(S|Z) to be the optimal key rate using shared randomness, where S is the Gàcs-Körner Common Information. We thus provide an operational interpretation of the conditional Gàcs- Körner Common Information. Additionally, we introduce simple example distributions in which the rate I(X: Y |Z) is achievable if and only if two-way communication is allowed

The role of adjuvant chemotherapy for patients with resected pancreatic cancer: Systematic review of randomized controlled trials and meta-analysis

Background: In patients undergoing surgery for resectable pancreatic cancer prognosis still remains poor. The role of adjuvant treatment strategies (including chemotherapy and chemoradiotherapy) following resection of pancreatic cancer remains controversial. Methods: A Medline-based literature search was undertaken to identify randomized controlled trials that evaluated adjuvant chemotherapy after complete macroscopic resection for cancer of the exocrine pancreas. Five trials of adjuvant chemotherapy were eligible and critically reviewed for this article. A meta-analysis (based on published data) was performed with survival (median survival time and 5-year survival rate) being the primary endpoint. Results: For the meta-analysis, 482 patients were allocated to the chemotherapy group and 469 patients to the control group. The meta-analysis estimate for prolongation of median survival time for patients in the chemotherapy group was 3 months (95% CI 0.3-5.7 months, p = 0.03). The difference in 5-year survival rate was estimated with 3.1% between the chemotherapy and the control group (95% CI -4.6 to 10.8%, p > 10.05). Conclusion: Currently available data from randomized trials indicate that adjuvant chemotherapy after resection of pancreatic cancer may substantially prolong disease-free survival and cause a moderate increase in overall survival. In the current meta-analysis, a significant survival benefit was only seen with regard to median survival, but not for the 5-year survival rate. The optimal chemotherapy regimen in the adjuvant setting as well as individualized treatment strategies (also including modern chemoradiotherapy regimens) still remain to be defined. Copyright (C) 2008 S. Karger AG, Basel

Entanglement can increase asymptotic rates of zero-error classical communication over classical channels

It is known that the number of different classical messages which can be communicated with a single use of a classical channel with zero probability of decoding error can sometimes be increased by using entanglement shared between sender and receiver. It has been an open question to determine whether entanglement can ever increase the zero-error communication rates achievable in the limit of many channel uses. In this paper we show, by explicit examples, that entanglement can indeed increase asymptotic zero-error capacity, even to the extent that it is equal to the normal capacity of the channel. Interestingly, our examples are based on the exceptional simple root systems E7 and E8.Comment: 14 pages, 2 figur

Quantum walks can find a marked element on any graph

We solve an open problem by constructing quantum walks that not only detect but also find marked vertices in a graph. In the case when the marked set $M$ consists of a single vertex, the number of steps of the quantum walk is quadratically smaller than the classical hitting time $HT(P,M)$ of any reversible random walk $P$ on the graph. In the case of multiple marked elements, the number of steps is given in terms of a related quantity $HT^+(\mathit{P,M})$ which we call extended hitting time. Our approach is new, simpler and more general than previous ones. We introduce a notion of interpolation between the random walk $P$ and the absorbing walk $P'$, whose marked states are absorbing. Then our quantum walk is simply the quantum analogue of this interpolation. Contrary to previous approaches, our results remain valid when the random walk $P$ is not state-transitive. We also provide algorithms in the cases when only approximations or bounds on parameters $p_M$ (the probability of picking a marked vertex from the stationary distribution) and $HT^+(\mathit{P,M})$ are known.Comment: 50 page