Matter in transition

We explore a novel type of transition in certain 6D and 4D quantum field theories, in which the matter content of the theory changes while the gauge group and other parts of the spectrum remain invariant. Such transitions can occur, for example, for SU(6) and SU(7) gauge groups, where matter fields in a three-index antisymmetric representation and the fundamental representation are exchanged in the transition for matter in the two-index antisymmetric representation. These matter transitions are realized by passing through superconformal theories at the transition point. We explore these transitions in dual F-theory and heterotic descriptions, where a number of novel features arise. For example, in the heterotic description the relevant 6D SU(7) theories are described by bundles on K3 surfaces where the geometry of the K3 is constrained in addition to the bundle structure. On the F-theory side, non-standard representations such as the three-index antisymmetric representation of SU(N) require Weierstrass models that cannot be realized from the standard SU(N) Tate form. We also briefly describe some other situations, with groups such as Sp(3), SO(12), and SU(3), where analogous matter transitions can occur between different representations. For SU(3), in particular, we find a matter transition between adjoint matter and matter in the symmetric representation, giving an explicit Weierstrass model for the F-theory description of the symmetric representation that complements another recent analogous construction.Comment: 107 pages, 3 figures, 32 tables. In version 2, one figure and comments added on the geometry of matter transition

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What Determines Firm Size?

Motivated by theories of the firm, which we classify as technological' or organizational,' we analyze the determinants of firm size across industries and across countries in a sample of 15 European countries. We find that, on average, firms facing larger markets are larger. At the industry level, we find firms in the utility sector are large, perhaps because they enjoy a natural, or officially sanctioned, monopoly. Capital intensive industries, high wage industries, and industries that do a lot of R&D have larger firms, as do industries that require little external financing. At the country level, the most salient findings are that countries with efficient judicial systems have larger firms, and, correcting for institutional development, there is little evidence that richer countries have larger firms. Interestingly, institutional development, such as greater judicial efficiency, seems to be correlated with lower dispersion in firm size within an industry. The effects of interactions (between an industry's characteristics and a country's environment) on size are perhaps the most novel results in the paper, and are best able to discriminate between theories. As the judicial system improves, the difference in size between firms in capital intensive industries and firms in industries that use little physical capital diminishes, a finding consistent with size of firms in industries dependent on external finance is larger in countries with better financial markets, suggesting that financial constraints limit average firm size.

Group membership in asynchronous distributed environments using logically ordered views

A group membership protocol ensures agreement and consistent commit actions among group members to maintain a sequence of identical group views in spite of continuous changes, either voluntary or otherwise, in processors' membership status. In asynchronous distributed environments, such consistency among group views must be guaranteed using messages over a network which does not bound message delivery times. Assuming a network that provides a reliable, FIFO channel between any pair of processors, one approach to designing such a protocol is to centralize the responsibility to detect changes, ensure agreement, and commit them consistently in a single manager process. This approach is complicated by the fact that a protocol to elect a new manager with a consistent membership proposal must be executed when the manager itself fails. In this report, we present a membership protocol based on ordering of group members in a logical ring that eliminates the need for such centralized responsibility. Agreement and commit actions are token-based and the protocol ensures that no tokens are lost or duplicated due to changes in membership. The cost of committing a change is 2n point-to-point messages over FIFO channels where n is the group size. The protocol correctness has been proven formally. Agreement, Asynchronous, Commit, Distributed, Failure, Group Membership, Logical Ring, Reliable Multicast, TokenMonterey, California. Naval Postgraduate Schoolhttp://archive.org/details/groupmembershipi00shukMonterey, California. Naval Postgraduate SchoolNAApproved for public release; distribution is unlimited

Forbidden oxygen lines at various nucleocentric distances in comets

To study the formation of the [OI] lines - i.e., 5577 A (the green line), 6300 A and 6364 A (the two red lines) - in the coma of comets and to determine the parent species of the oxygen atoms using the green to red-doublet emission intensity ratio (G/R ratio) and the lines velocity widths. We acquired at the ESO VLT high-resolution spectroscopic observations of comets C/2002 T7 (LINEAR), 73P-C/Schwassmann-Wachmann 3, 8P/Tuttle, and, 103P/Hartley 2 when they were close to the Earth (< 0.6 au). Using the observed spectra, we determined the intensities and the widths of the three [OI] lines. We have spatially extracted the spectra in order to achieve the best possible resolution of about 1-2", i.e., nucleocentric projected distances of 100 to 400 km depending on the geocentric distance of the comet. We have decontaminated the [OI] green line from C2 lines blends. It is found that the observed G/R ratio on all four comets varies as a function of nucleocentric projected distance. This is mainly due to the collisional quenching of O(1S) and O(1D) by water molecules in the inner coma. The observed green emission line width is about 2.5 km/s and decreases as the distance from the nucleus increases which can be explained by the varying contribution of CO2 to the O(1S) production in the innermost coma. The photodissociation of CO2 molecules seems to produce O(1S) closer to the nucleus while the water molecule forms all the O(1S) and O(1D) atoms beyond 1000 km. Thus we conclude that the main parent species producing O(1S) and O(1D) in the inner coma is not always the same. The observations have been interpreted in the framework of the coupled-chemistry-emission model of Bhardwaj & Raghuram (2012) and the upper limits of CO2 relative abundances are derived from the observed G/R ratios. Measuring the [OI] lines could indeed provide a new way to determine the CO2 relative abundance in comets.Comment: accepted for publication in A&A, the abstract is shortene

Moduli-dependent Calabi-Yau and SU(3)-structure metrics from Machine Learning

We use machine learning to approximate Calabi-Yau and SU(3)-structure metrics, including for the first time complex structure moduli dependence. Our new methods furthermore improve existing numerical approximations in terms of accuracy and speed. Knowing these metrics has numerous applications, ranging from computations of crucial aspects of the effective field theory of string compactifications such as the canonical normalizations for Yukawa couplings, and the massive string spectrum which plays a crucial role in swampland conjectures, to mirror symmetry and the SYZ conjecture. In the case of SU(3) structure, our machine learning approach allows us to engineer metrics with certain torsion properties. Our methods are demonstrated for Calabi-Yau and SU(3)-structure manifolds based on a one-parameter family of quintic hypersurfaces in $\mathbb{P}^4.$Comment: 27+15 pages, 12 figures, 3 table

Occupational (Im)mobility in the Global Care Economy: The Case of Foreign-Trained Nurses in the Canadian Context

The twenty-first century has witnessed a number of significant demographic and political shifts that have resulted in a care crisis. Addressing the deficit of care provision has led many nations to actively recruit migrant care labour, often under temporary forms of migration. The emergence of this phenomenon has resulted in a rich field of analysis using the lens of care, including the idea of the Global Care Chain. Revisions to this conceptualization have pushed for its extension beyond domestic workers in the home to include skilled workers in other institutional settings, particularly nurses in hospitals and long-term care settings. Reviewing relevant literature on migrant nurses, this article explores the labour market experiences of internationally educated nurses in Canada. The article reviews research on the barriers facing migrant nurses as they transfer their credentials to the Canadian context. Analysis of this literature suggests that internationally trained nurses experience a form of occupational (im)mobility, paradoxical, ambiguous and contingent processes that exploit global mobility, and results in the stratified incorporation of skilled migrant women into healthcare workplaces

Design and Development IoT based Smart Energy Management Systems in Buildings through LoRa Communication Protocol

Energy management is a vital tool for reducing significant supply-side deficits and increasing the efficiency of power generation. The present energy system standard emphasizes lowering the total cost of power without limiting consumption by opting to lower electricity use during peak hours. The previous problem necessitates the development and growth of a flexible and mobile technology that meets the needs of a wide variety of customers while preserving the general energy balance. In order to replace a partial load decrease in a controlled manner, smart energy management systems are designed, according to the preferences of the user, for the situation of a full power loss in a particular region. Smart Energy Management Systems incorporate cost-optimization methods based on human satisfaction with sense input features and time of utilization. In addition to developing an Internet of Things (IoT) for data storage and analytics, reliable LoRa connectivity for residential area networks is also developed. The proposed method is named as LoRa_bidirectional gated recurrent neural network (LoRa_ BiGNN) model which achieves 0.11 and 0.13 of MAE, 0.21 and 0.23 of RMSE, 0.34 and 0.23 of MAPE for heating and cooling loads

A Novel Cryptography-Based Multipath Routing Protocol for Wireless Communications

Communication in a heterogeneous, dynamic, low-power, and lossy network is dependable and seamless thanks to Mobile Ad-hoc Networks (MANETs). Low power and Lossy Networks (LLN) Routing Protocol (RPL) has been designed to make MANET routing more efficient. For different types of traffic, RPL routing can experience problems with packet transmission rates and latency. RPL is an optimal routing protocol for low power lossy networks (LLN) having the capacity to establish a path between resource constraints nodes by using standard objective functions: OF0 and MRHOF. The standard objective functions lead to a decrease in the network lifetime due to increasing the computations for establishing routing between nodes in the heterogeneous network (LLN) due to poor decision problems. Currently, conventional Mobile Ad-hoc Network (MANET) is subjected to different security issues. Weathering those storms would help if you struck a good speed-memory-storage equilibrium. This article presents a security algorithm for MANET networks that employ the Rapid Packet Loss (RPL) routing protocol. The constructed network uses optimization-based deep learning reinforcement learning for MANET route creation. An improved network security algorithm is applied after a route has been set up using (ClonQlearn). The suggested method relies on a lightweight encryption scheme that can be used for both encryption and decryption. The suggested security method uses Elliptic-curve cryptography (ClonQlearn+ECC) for a random key generation based on reinforcement learning (ClonQlearn). The simulation study showed that the proposed ClonQlearn+ECC method improved network performance over the status quo. Secure data transmission is demonstrated by the proposed ClonQlearn + ECC, which also improves network speed. The proposed ClonQlearn + ECC increased network efficiency by 8-10% in terms of packet delivery ratio, 7-13% in terms of throughput, 5-10% in terms of end-to-end delay, and 3-7% in terms of power usage variation