An Improved Experiment to Determine the `Past of a Particle' in the Nested Mach-Zehnder Interferometer

We argue that the modification proposed by Li et al. [Chin. Phys. Lett. 32, 050303 (2015)] to the experiment of Danan et al. [Phys. Rev. Lett. 111, 240402 (2013)] does not test the past of the photon as characterised by local weak traces. Instead of answering the questions: (i) Were the photons in A? (ii) Were the photons in B? (iii) Were the photons in C? the proposed experiment measures a degenerate operator answering the questions: (i) Were the photons in A? (ii) Were the photons in B and C together? A negative answer to the last question does not tell us if photons were present in B or C. A simple variation of the modified experiment does provide good evidence for the past of the photon in agreement with the results Danan et al. obtained.Comment: 3 pages, accepted for publication in Chinese Physics Letter

Coincident brane nucleation and the neutralization of \Lambda

Nucleation of branes by a four-form field has recently been considered in string motivated scenarios for the neutralization of the cosmological constant. An interesting question in this context is whether the nucleation of stacks of coincident branes is possible, and if so, at what rate does it proceed. Feng et al. have suggested that, at high ambient de Sitter temperature, the rate may be strongly enhanced, due to large degeneracy factors associated with the number of light species living on the worldsheet. This might facilitate the quick relaxation from a large effective cosmological constant down to the observed value. Here, we analyse this possibility in some detail. In four dimensions, and after the moduli are stabilized, branes interact via repulsive long range forces. Because of that, the Coleman-de Luccia (CdL) instanton for coincident brane nucleation may not exist, unless there is some short range interaction which keeps the branes together. If the CdL instanton exists, we find that the degeneracy factor depends only mildly on the ambient de Sitter temperature, and does not switch off even in the case of tunneling from flat space. This would result in catastrophic decay of the present vacuum. If, on the contrary, the CdL instanton does not exist, coindident brane nucleation may still proceed through a "static" instanton, representing pair creation of critical bubbles -- a process somewhat analogous to thermal activation in flat space. In that case, the branes may stick together due to thermal symmetry restoration, and the pair creation rate depends exponentially on the ambient de Sitter temperature, switching off sharply as the temperature approaches zero. Such static instanton may be well suited for the "saltatory" relaxation scenario proposed by Feng et al.Comment: 38 pages, 6 figures. Replaced with typos correcte

Auditoría tributaria a la empresa productos alimenticios San Salvador de la ciudad de Riobamba, provincia de Chimborazo, periodo 2020

La Empresa Productos Alimenticios San Salvador presenta comprobantes de retenciones autorizados fuera del plazo establecido por el reglamento, con respecto a la información presentada a la administración tributaria existe diferencia con la información real de la empresa, lo cual ha generado diferencias en valores, por lo tanto el objetivo de la presente investigación fue realizar una Auditoría Tributaria a la Empresa Productos Alimenticios San Salvador, de la ciudad de Riobamba, provincia de Chimborazo, mediante la utilización de la normativa legal tributaria con la finalidad de verificar el cumplimiento de las obligaciones tributarias en el período fiscal 2020. Para su ejecución se desarrolló el marco metodológico que tuvo un enfoque cualitativo y cuantitativo, el nivel de investigación exploratoria y descriptiva, se utilizó un diseño no experimental debido a que no se manipularon las variables de estudio y al llevar a cabo sobre un determinado periodo de tiempo se empleó el diseño transversal, para la recolección de datos se aplicó el tipo de estudio documental y de campo, mediante el empleo de métodos e instrumentos de investigación como entrevista, encuesta y cuestionarios de control interno basado en el método COSO I, se empleó el método deductivo e inductivo que permitieron obtener las conclusiones. Se logró determinar que existen deficiencias y variaciones en valores en los documentos justificantes, desconocimiento de los personales de la empresa sobre sus funciones y en concordancia con las normativas legales tributarias se generó los hallazgos correspondientes, en este contexto se concluye que la empresa no cuenta con manual de funciones para mejorar el desempeño organizacional, existe descuido profesional del personal contable que incide en la omisión de verificación y conciliación de los valores a ser declarados, proponiendo así cumplir con las recomendaciones emitidas en el informe con el objetivo de mejorar la productividad, gestión tributaria y empresarialThe company Productos Alimenticios San Salvador presents withholding vouchers authorized outside the term established by the regulations; concerning the information submitted to the tax administration, there is a difference in the basic knowledge of the company, which has generated differences in values. Therefore, this research aimed to conduct a tax audit of the company Productos Alimenticios San Salvador in the city of Riobamba, province of Chimborazo, using the legal tax regulations to verify compliance with tax obligations in the fiscal period of 2020. For its execution, the methodological framework was developed with a qualitative and quantitative approach, the exploratory and descriptive level of research, and a non-experimental design was used because the study variables were not manipulated, and the cross-sectional design was used to carry out the study over a certain period, for data collection the type of documentary and field study was applied, through the use of research methods and instruments such as interview, survey and internal control questionnaires based on the COSO I method. The deductive and inductive approach was used to obtain the conclusions. It was determined that there are deficiencies and variations in values in the supporting documents and a lack of knowledge of the company's personnel about their functions, and by the legal tax regulations, the corresponding findings were generated; in this context, it is concluded that the company does not have a manual of functions to improve organizational performance. Professional carelessness on the part of the accounting personnel results in the omission of verification and reconciliation of the values to be declared, thus proposing to comply with the recommendations issued in the report to improve productivity, tax, and business managemen

Editorial: Building Back Progress Towards Meeting Sustainable Development Goal 3 by 2030: Applications of AI and Digital Solutions.

The COVID-19 pandemic has exposed the vulnerability of many health systems across the world, including some of the highest income countries, when they were overwhelmed by rapid surges of demand for health services and disruptions to the global healthcare supply chain. The suspension or even closure of some life-saving healthcare facilities and provisions, such as childhood immunization programmes, coupled with the fear of disease exposure, have made access to healthcare challenging. These factors may have led to a rise in preventable deaths due to delayed diagnosis of cancers and other diseases, and poor management of existing chronic conditions such as diabetes

Increased MicroRNA Activity in Human Cancers

MicroRNAs (miRNAs) are small regulatory RNAs that act by blocking the translation and increasing the degradation of target transcripts. MiRNAs play a critical role in many biological processes including development and differentiation and many studies have shown that major changes in miRNA levels occur in cancer. Since miRNAs degrade target messages, we used this property to develop a novel computational method aimed at determining the actual biological activity of miRNAs using variations in gene expression. Using the method described here, we quantified miRNA activity in papillary thyroid carcinoma and breast cancer, and found a strong and distinctive signal of increased global miRNA activity, embedded in the pertaining gene expression measurements. Interestingly, we found that in these two cancers, miRNA activity is globally increased, and is associated with a global downregulation of miRNA target genes. This downreguation of miRNA regulated genes is particularly noticeable for genes carrying multiple target sites for miRNAs. Among the miRNA-repressed genes, we found a significant enrichment of known tumor suppressors, thereby suggesting that the increased miRNA activity was indeed tumorigenic

Erodibility Evaluation of an Unlined Rock Spillway: Comparison Between the Erodibility Index Method and a New Method Based on Block Theory

Following the 2017 events at the Oroville Dam spillways that prompted evacuation of nearly 200,000 downstream residents and resulted in over $1B USD repair costs, there is highlighted focus on evaluation of spillways (both lined and unlined) at dams across the USA. In the case of unlined channels, flow conditions are often complex which presents several challenges for erodibility evaluation given methods are often based on idealized circumstances. High-resolution data available for the site (both in terms of 3D point cloud geometry data for the rock mass and 3D CFD model simulations of flow conditions) permitted a more detailed analysis of the scouring process, which ultimately provided deeper insight into scour potential. Two methods were used for the analysis; the semi-empirical Erodibility Index Method and a new, physics-based method using Block Theory, and a comparison between the two was made yielding informative results

An isolated chemolithoautotrophic ecosystem deduced from environmental isotopes: Ayyalon cave (Israel)

The stable isotopes composition of chemolithoautotrophic cave ecosystems is known to differ from epigenic caves. Here we show that in addition, dead carbon (devoid of 14C), is utilized and transferred throughout this ecosystem, rendering it unsuitable for radiocarbon dating. The connectivity of the Ayyalon Cave ecosystem with the surface is studied, along with its sources of energy and carbon, as well as the interconnections between its constituents. We use isotopic evidence to show that its ancient resilient ecosystem is based on an underground food web depending on rich biomass production by chemolithoautotrophic nutrient supplies, detached from surface photosynthesis. Carbon isotopic values indicate that: (1) the microbial biota use bicarbonate from the groundwater (23.34 pMC [% of modern carbon]) rather than the atmospheric CO2 above the water (71.36 pMC); (2) the depleted 14C signal is transferred through the entire ecosystem, indicating that the ecosystem is well-adapted and based on the cave biofilm which is in turn based on groundwater-dissolved inorganic carbon. Incubation of Ayyalon biofilm with 14C-labelled bicarbonate indicates uptake of the radio-labeled bicarbonate by sulfur-oxidizing proteobacteria Beggiatoa, suggesting that these sulfur-oxidizing microorganisms use the water-dissolved inorganic carbon for chemolithoautotrophic carbon fixation. Organic matter in the cave is much lighter in its stable nitrogen and carbon isotopes compared with respective surface values, as expected in chemolithoautotrophic systems. This evidence may be applicative to subsurface voids of ancient Earth environments and extraterrestrial systems