Possible cosmological implications in electrodynamics due to variations of the fine structure constant

Astronomical observations are suggesting that the fine structure constant varies cosmologically. We present an analysis on the consequences that these variations might induce on the electromagnetic field as a whole. We show that under these circumstances the electrodynamics in vacuum could be described by two fields, the ``standard'' Maxwell's field and a new scalar field. We provide a generalised Lorentz force which can be used to test our results experimentally.Comment: 7 pages, no figures. Accepted for publication in Rev. Mex. Fis. (Some extra information included, references added and small corrections made to the original version

Optimal Joins Using Compact Data Structures

Worst-case optimal join algorithms have gained a lot of attention in the database literature. We now count with several algorithms that are optimal in the worst case, and many of them have been implemented and validated in practice. However, the implementation of these algorithms often requires an enhanced indexing structure: to achieve optimality we either need to build completely new indexes, or we must populate the database with several instantiations of indexes such as B+-trees. Either way, this means spending an extra amount of storage space that may be non-negligible. We show that optimal algorithms can be obtained directly from a representation that regards the relations as point sets in variable-dimensional grids, without the need of extra storage. Our representation is a compact quadtree for the static indexes, and a dynamic quadtree sharing subtrees (which we dub a qdag) for intermediate results. We develop a compositional algorithm to process full join queries under this representation, and show that the running time of this algorithm is worst-case optimal in data complexity. Remarkably, we can extend our framework to evaluate more expressive queries from relational algebra by introducing a lazy version of qdags (lqdags). Once again, we can show that the running time of our algorithms is worst-case optimal

Optimized generation of spatial qudits by using a pure phase spatial light modulator

We present a method for preparing arbitrary pure states of spatial qudits, namely, D-dimensional (D > 2) quantum systems carrying information in the transverse momentum and position of single photons. For this purpose, a set of D slits with complex transmission are displayed on a spatial light modulator (SLM). In a recent work we have shown a method that requires a single phase-only SLM to control independently the complex coefficients which define the quantum state of dimension D. The amplitude information was codified by introducing phase gratings inside each slit and the phase value of the complex transmission was added to the phase gratings. After a spatial filtering process we obtained in the image plane the desired qudit state. Although this method has proven to be a good alternative to compact the previously reported architectures, it presents some features that could be improved. In this paper we present an alternative scheme to codify the required phase values that minimizes the effects of temporal phase fluctuations associated to the SLM where the codification is carried on. In this scheme the amplitudes are set by appropriate phase gratings addressed at the SLM while the relative phases are obtained by a lateral displacement of these phase gratings. We show that this method improves the quality of the prepared state and provides very high fidelities of preparation for any state. An additional advantage of this scheme is that a complete 2\pi modulation is obtained by shifting the grating by one period, and hence the encoding is not limited by the phase modulation range achieved by the SLM. Numerical simulations, that take into account the phase fluctuations, show high fidelities for thousands of qubit states covering the whole Bloch sphere surface. Similar analysis are performed for qudits with D = 3 and D = 7.Comment: 12 pages, 7 figure

Missouri River history, floodplain construction, and soil formation in southwestern Iowa

The Platte River has influenced the Missouri River below the mouth of the Platte by contributing sizable suspended and coarser-textured bed loads. Consequently, the Missouri River has been and is a braided stream in a reach about 43 miles long below the mouth of the Platte. In this reach the channel is wider, is less sinuous, has greater low-water slope profile, and contains numerous bars and islands. The Otoe Bend area, in this reach of the Missouri River near the southwestern corner of Iowa, has inherited these channel characteristics. By use of historic maps and aerial photographs, the lateral shifting of the river channel at Otoe Bend may be reconstructed. Adjustments of scale and geographic locations must be made to compare features of all maps and aerial photographs to the present landforms in the area. The older maps usually are not as accurate as present-day cartography with photogrammetric field control. Within the different levels of cartographic accuracy, however, correlation of landforms can be made by similarity of features or similarity of sequences of features

Smart Manufacturing for Cal Poly\u27s IME Curriculum

California Polytechnic State University, San Luis Obispo (Cal Poly) takes pride of supporting one of the nation’s strongest undergraduate Industrial and Manufacturing Engineering programs. However, as industry evolves to accommodate advancing computing power, improved manufacturing algorithms, and improved robotics, it is imperative that Cal Poly’s curriculum evolves in parallel. Smart manufacturing is the future of the manufacturing industry, and Cal Poly is searching for the ideal method to teach and integrate Smart Manufacturing into its classes. With its upcoming switch to the semester system, coupled with its “Learn by Doing” motto, the department is at an ideal period for the integration of advanced technology to revamp their lecture and lab programs. While smart manufacturing is a broad subject, it can be boiled down to a simple definition, “a technology driven approach that utilizes internet-connected machinery to monitor the production process. The goal of smart manufacturing is to identify opportunities to automate operations and use data analytics to improve manufacturing performance” (Burns, 2019). Smart manufacturing can vary from plant to plant but is centralized around the integration of IIoT (Industrial Internet of Things) with computers, sensors, hardware, or software. In today’s post-pandemic environment, the importance and relevancy of smart manufacturing continues to grow. With smart manufacturing, organizations are unlocking new methods of furthering both economic and environmental sustainability. While smart manufacturing has only grown in importance and relevancy over the past decade, it has not yet been integrated in Cal Poly’s Industrial and Manufacturing (IME) curriculum. Furthermore, there are large quantities of data collected during IME laboratory activities, yet IME lab activity data collection and learning processes do not mirror current industry practices. Currently, there is no infrastructure for professors to conduct groundbreaking, relevant research on smart manufacturing within the IME department. All these needs propose a challenge that needs to be addressed: how to incorporate smart manufacturing principles and hands-on experience into an evolving curriculum effectively and sustainably? Group 16 plans on laying the framework for smart manufacturing technology within Cal Poly’s IME department. This report will outline their research and approach to tacking the lack of smart manufacturing within the IME department and will illustrate their final deliverables: a physical and digital infrastructure that emphasizes smart manufacturing technology (that is accessible to both students and professors alike), a user guide of software to operate this system, and a lab activity that has been tailored for the instruction of smart manufacturing in specific classes. This foundation will foster the growth and learning of smart manufacturing within the Cal Poly IME department for years to come

High-dimensional states of light with full control of transverse path and OAM degrees of freedom

We present here a compact scheme for the generation of high-dimensional states of light encoded in the transverse path variable of photons that carry orbital angular momentum. We use a programmable spatial light modulator in phase configuration to create correlations between these two spatial degrees of freedom. With our setup we are able to control, independently, the relative phases and amplitudes of the path superposition in addition to the topological charge of each path. Moreover, we engineer correlations that emulate bipartite quantum states of dimensions $d\times m$. Experimental results from the characterization of different generated states of dimensions up to $9\times 5$ are in excellent agreement with the numerical simulations. Fidelity with the target state is, for all cases, above $95\%$.Comment: minor change

APLF (C2orf13) is a novel component of poly(ADP-ribose) signaling in mammalian cells

APLF is a novel protein of unknown function that accumulates at sites of chromosomal DNA strand breakage via forkhead-associated (FHA) domain-mediated interactions with XRCC1 and XRCC4. APLF can also accumulate at sites of chromosomal DNA strand breaks independently of the FHA domain via an unidentified mechanism that requires a highly conserved C-terminal tandem zinc finger domain. Here, we show that the zinc finger domain binds tightly to poly(ADP-ribose), a polymeric posttranslational modification synthesized transiently at sites of chromosomal damage to accelerate DNA strand break repair reactions. Protein poly(ADP-ribosyl)ation is tightly regulated and defects in either its synthesis or degradation slow global rates of chromosomal single-strand break repair. Interestingly, APLF negatively affects poly(ADP-ribosyl)ation in vitro, and this activity is dependent on its capacity to bind the polymer. In addition, transient overexpression in human A549 cells of full-length APLF or a C-terminal fragment encoding the tandem zinc finger domain greatly suppresses the appearance of poly(ADP-ribose), in a zinc finger-dependent manner. We conclude that APLF can accumulate at sites of chromosomal damage via zinc finger-mediated binding to poly(ADP-ribose) and is a novel component of poly(ADP-ribose) signaling in mammalian cells