Miracle-dz/UniFAR-FTUs huggingface dataset:
Quantum repeaters in space

Long-distance entanglement is a very precious resource, but its distribution is very difficult due to the exponential losses of light in optical fibres. A possible solution consists in the use of quantum repeaters, based on entanglement swapping (ES) or quantum error correction. Alternatively, satellite-based free-space optical links can be exploited, achieving better loss-distance scaling. We propose to combine these two ingredients, quantum repeaters and satellite-based links, into a scheme that allows to achieve entanglement distribution over global distances with a small number of intermediate untrusted nodes. The entanglement sources, placed on satellites, send quantum states encoded in photons towards orbiting quantum repeater stations, where ES is performed. The performance of this repeater chain is assessed in terms of the secret key rate achievable by the BBM92 cryptographic protocol. We perform a comparison with other repeater chain architectures and show that our scheme, even though more technically demanding, is superior in many situations of interest. Finally, we analyse strengths and weaknesses of the proposed scheme and discuss exemplary orbital configurations. The integration of satellite-based links with ground repeater networks can be envisaged to represent the backbone of the future quantum internet.
The effects of culture concentration and age, time, and temperature on bacterial attachment to polystyrene

The attachment of a marine pseudomonad to polystyrene was found to be dependent upon (a) culture concentration, (b) the time allowed for attachment, (c) the growth phase of the culture, and (d) temperature. The number of attached cells increased with both culture concentration and the time allowed for attachment, until the attachment surface approached saturation. The number of cells which attached and the rate of attachment was greatest with log-phase cultures, and progressively decreased with stationary and death-phase cultures. A temperature of 3 °C ± 1 noticeably decreased the proportion of stationary phase cells which attached, compared with cells at 20 °C ± 1. These results can be described by a model based on physicochemical adsorption, which suggests that non-biological processes may play a major role in the initial events of bacterial adhesion.
Motif Discovery Algorithms in Static and Temporal Networks: A Survey

Motifs are the fundamental components of complex systems. The topological structure of networks representing complex systems and the frequency and distribution of motifs in these networks are intertwined. The complexities associated with graph and subgraph isomorphism problems, as the core of frequent subgraph mining, directly impact the performance of motif discovery algorithms. Researchers have adopted different strategies for candidate generation and enumeration and frequency computation to cope with these complexities. Besides, in the past few years, there has been an increasing interest in the analysis and mining of temporal networks. In contrast to their static counterparts, these networks change over time in the form of insertion, deletion or substitution of edges or vertices or their attributes. In this article, we provide a survey of motif discovery algorithms proposed in the literature for mining static and temporal networks and review the corresponding algorithms based on their adopted strategies for candidate generation and frequency computation. As we witness the generation of a large amount of network data in social media platforms, bioinformatics applications and communication and transportation networks and the advance in distributed computing and big data technology, we also conduct a survey on the algorithms proposed to resolve the CPU-bound and I/O bound problems in mining static and temporal networks.
Obtaining the sphaleron field configurations with gradient flow

We propose a formalism to obtain the electroweak sphaleron, which is one of the static classical solutions, using the gradient flow method. By adding a modification term to the gradient flow equation, we can obtain the sphaleron configuration as a stable fixed point of the flow in the large flow time. Applying the method to the SU(2)-Higgs model (the Weinberg angle θW is 0) in four dimensions, we obtain the sphaleron configuration whose energy coincides with previous studies numerically. We can also show that the Chern-Simons number of the solution has a half-integer.
Quasi-Local 3D Quantum Gravity : Exact Amplitude and Holography

This thesis is dedicated to the study of quasi-local boundary in quantum gravity. In particular, we focus on the three-dimensional space-time case. This research takes root in the holographic principle, which conjectures that the geometry and the dynamic of a space-time region can be entirely described by a theory living on the boundary of this given region. The most studied case of this principle is the AdS/CFT correspondence, where the quantum fluctuations of an asymptotically AdS space are described by a conformal field theory living at spatial infinity, invariant under the Virasoro group. The philosophy applied in this thesis however differs from the AdS/CFT case. I chose to focus on the case of quasi-local holography, i.e. for a bounded region of space-time with a boundary at a finite distance. The objective is to clarify the bulk-boundary relation in quantum gravity described by the Ponzano-Regge model, which defined a model for 3D gravity via a discrete path integral.I present the first perturbative and exact computations of the Ponzano-Regge amplitude on a torus with a 2D boundary state. After the presentation of the general framework for the 3D amplitude in terms of the 2D boundary state, we focus on the case of the 2D torus, that found an application in the study of the thermodynamics of the BTZ black hole. First, the 2D boundary is described by a coherent spin network state in the semi-classical regime. The stationary phase approximation allows to recover in the asymptotic limit the usual amplitude for 3D quantum gravity as the character of the symmetry of asymptotically flat gravity, the BMS group. Then we introduce a new type of coherent boundary state, which allows an exact evaluation of the amplitude for 3D quantum gravity. We obtain a complex regularization of the BMS character. The possibility of this exact computation suggests the existence of a (quasi)-integrable structure, linked to the symmetries of 3D quantum gravity with 2D finite boundary.
Mirror Descent Policy Optimization

We propose deep Reinforcement Learning (RL) algorithms inspired by mirror descent, a well-known first-order trust region optimization method for solving constrained convex problems. Our approach, which we call as Mirror Descent Policy Optimization (MDPO), is based on the idea of iteratively solving a `trust-region' problem that minimizes a sum of two terms: a linearization of the objective function and a proximity term that restricts two consecutive updates to be close to each other. Following this approach we derive on-policy and off-policy variants of the MDPO algorithm and analyze their performance while emphasizing important implementation details, motivated by the existing theoretical framework. We highlight the connections between on-policy MDPO and two popular trust region RL algorithms: TRPO and PPO, and conduct a comprehensive empirical comparison of these algorithms. We then derive off-policy MDPO and compare its performance to existing approaches. Importantly, we show that the theoretical framework of MDPO can be scaled to deep RL while achieving good performance on popular benchmarks.
List Decodable Mean Estimation in Nearly Linear Time

Learning from data in the presence of outliers is a fundamental problem in statistics. Until recently, no computationally efficient algorithms were known to compute the mean of a high dimensional distribution under natural assumptions in the presence of even a small fraction of outliers. In this paper, we consider robust statistics in the presence of overwhelming outliers where the majority of the dataset is introduced adversarially. With only an $\alpha < 1/2$ fraction of “in-liers” (clean data) the mean of a distribution is unidentifiable. However, in their influential work, [1] introduces a polynomial time algorithm recovering the mean of distributions with bounded covariance by outputting a succinct list of $O(1/\alpha)$ candidate solutions, one of which is guaranteed to be close to the true distributional mean; a direct analog of ‘List Decoding’ in the theory of error correcting codes. In this work, we develop an algorithm for list decodable mean estimation in the same setting achieving up to constants the information theoretically optimal recovery, optimal sample complexity, and in nearly linear time up to polylogarithmic factors in dimension. Our conceptual innovation is to design a descent style algorithm on a nonconvex landscape, iteratively removing minima to generate a succinct list of solutions. Our runtime bottleneck is a saddle-point optimization for which we design custom primal dual solvers for generalized packing and covering SDP's under Ky-Fan norms, which may be of independent interest. We refer the reader to [2] for the full version of this paper.
Optical spectra of FO Aquarii during low and high accretion rates

Between May 2016 and September 2018, the intermediate polar (IP) FO Aquarii exhibited two distinct low states and one failed low state. We present optical spectroscopy of FO Aquarii throughout this period, making this the first detailed study of an accretion disc during a low state in any IP. Analysis of these data confirm that the low states are the result of a drop in the mass transfer rate between the secondary star and the magnetic white dwarf primary, and are characterised by a decrease in the system's brightness coupled with a change of the system's accretion structures from an accretion disc-fed geometry to a combination of disc-fed and ballistic stream-fed accretion, and that effects from accretion onto both magnetic poles become detectable. The failed low state only displays a decrease in brightness, with the accretion geometry remaining primarily disc-fed. We also find that the WD appears to be exclusively accretion disc-fed during the high state. There is evidence for an outflow close to the impact region between the ballistic stream and the disc which is detectable in all of the states. Finally, there is marginal evidence for narrow high velocity features in the H$\alpha$ emission line during the low states which may arise due to an outflow from the WD. These features may be evidence of a collimated jet, a long predicted yet elusive feature of cataclysmic variables.
Studying Type II supernovae as cosmological standard candles using the Dark Energy Survey

Despite vast improvements in the measurement of the cosmological parameters, the nature of dark energy and an accurate value of the Hubble constant (H0) in the Hubble–Lemaitre law remain unknown. To break the current impasse, it is necessary to develop as many independent techniques as possible, such as the use of Type II supernovae (SNe II). The goal of this paper is to demonstrate the utility of SNe II for deriving accurate extragalactic distances, which will be an asset for the next generation of telescopes where more-distant SNe II will be discovered. More specifically, we present a sample from the Dark Energy Survey Supernova Program (DES-SN) consisting of 15 SNe II with photometric and spectroscopic information spanning a redshift range up to 0.35. Combining our DES SNe with publicly available samples, and using the standard candle method (SCM), we construct the largest available Hubble diagram with SNe II in the Hubble flow (70 SNe II) and find an observed dispersion of 0.27 mag. We demonstrate that adding a colour term to the SN II standardization does not reduce the scatter in the Hubble diagram. Although SNe II are viable as distance indicators, this work points out important issues for improving their utility as independent extragalactic beacons: find new correlations, define a more standard subclass of SNe II, construct new SN II templates, and dedicate more observing time to high-redshift SNe II. Finally, for the first time, we perform simulations to estimate the redshift-dependent distance-modulus bias due to selection effects.
Biological Characterization of Neurokinin Antagonists Discovered Through Screening of a Combinatorial Library

Recent advances in combinatorial chemistry have resulted in the rapid screening of libraries against biological targets. Another advance in biological screening is the ability to design and utilize novel, automated, nonradioactive assays for targets of pharmaceutical interest. Using encoding technology and europium time-resolved fluorescence, we have designed primary receptor binding assays to define active compounds against the neurokinin-1 and neurokinin-2 receptor subtypes. In addition, a secondary, cell-based, functional assay measuring intracellular calcium flux with calcium sensitive fluorophores was used to determine receptor agonist or antagonist activities. We adapted a cuvette based assay to a CCD camera and digital imaging system that allowed us to demonstrate functional receptor antagonist activity in all 96 wells of a microtiter plate simultaneously. The screening of a 20,000 member library using europium labeled neurokinin ligands resulted in the identification of 43 active compounds for neurokinin-1 and 27 for neurokinin-2. Through medicinal chemistry and structure-activity relationships, a compound was synthesized with balanced dual antagonist activity at both neurokinin receptors with greater than 100-fold less activity against the neurokinin-3 receptor subtype. The structure-activity relationships generated from this initial library can now be used to design a new focused library to improve on neurokinin-1/neurokinin-2 receptor potency and selectivity.
Stellar mass primordial black holes as cold dark matter

Primordial black holes (PBHs) might have formed in the early Universe due to the collapse of density fluctuations. PBHs may act as the sources for some of the gravitational waves recently observed. We explored the formation scenarios of PBHs of stellar mass, taking into account the possible influence of the QCD phase transition, for which we considered three different models: crossover model, bag model, and lattice fit model. For the fluctuations, we considered a running-tilt power-law spectrum; when these cross the ∼10^−9–10^−1 s Universe horizon they originate 0.05–500 M_⊙ PBHs that could (i) provide a population of stellar mass PBHs similar to the ones present on the binaries associated with all-known gravitational wave sources and (ii) constitute a broad-mass spectrum accounting for |${\sim}76{{\ \rm per\ cent}}$| of all cold dark matter in the Universe.
A simple formulation of non-Markovian SEIR

We present a formulation of the SEIR concept that represents the evolution of an epidemic under the assumption of homogeneity and uniformity of the microscopic parameters: rate of infection, incubation and recovery/removal times. Non-homogeneities in the basic parameters are easily included by integration for arbitrary distributions of incubation and removal times, recovering the classical SEIR model under the assumption of exponential distributions. We compare the solution to these equations, uSEIR, to two types of agent-based model simulations, a spatially homogeneous one where infection occurs by proximity, and a model on a scale-free network with varying clustering properties, where the infection between any two agents occurs via their link if it exists. We find good agreement in both cases with the uSEIR solution. Furthermore a family of asymptotic solutions of the uSEIR equations is found in terms of a logistic curve, which after a non-universal time shift, fits extremely well all the microdynamical simulations. A link to software packages for the numerical solution of the uSEIR equations is provided.
Movement and Growth of Neonate Eastern Massasaugas (Sistrurus catenatus)

Abstract Throughout the geographic range, adult Eastern Massasaugas (Sistrurus catenatus) exhibit plasticity in movement, fecundity, diet, and activity range size; however, the ecology of subadults remains unknown. We attached radio transmitters to 16 free-ranging neonate S. catenatus and monitored their movements and growth for up to 56 days prior to their initial hibernation. Neonate movement frequency (70%) was consistent with values reported for adults throughout the geographic range, but activity range size (0.36 ha) and mean daily distance moved (5.3 m) were smaller. Males gained significantly more mass than females over the first 50 days, but no difference in length was detected. Neonate S. catenatus returned to their general birthing area to overwinter. Because of ontogenetic shifts and differences in the spatial distribution of resources, regionally-specific management plans based on data for all age classes are essential in providing effective conservation measures.
Single-photon linear polarimeter based on a superconducting nanowire array

Superconducting nanowire single-photon detectors (SNSPDs) have attracted remarkable interest for visible and near infrared single-photon detection, owing to their outstanding performance. Conventional SNSPDs are generally used as binary photon-counting detector. Another important characteristic of light, i.e., polarization, has not been resolved using standalone SNSPDs. In this work, we simulated, fabricated, and characterized a linear polarimeter based on a four-pixel NbN superconducting nanowire array, capable of resolving the polarization state of linearly polarized light at the single-photon level. The detector array design is based on a division of focal plane sensor, in which the orientation of each nanowire division (pixel) is offset by 45 degree. Each single nanowire pixel operates as a combination of photon detector and almost linear polarization filter, with an average polarization extinction ratio of approximately 10. The total system detection efficiency with four pixels is approximately 1% at a total dark count rate of 680 cps, when the detector array is free-space coupled and illuminated with 1550 nm photons. The Stokes parameters are extracted from polarization measurements of the four pixels. The mean errors of the measured AoP and DoLP were about -3 degree and 0.12, respectively. Our results indicate that it is possible to develop a scalable polarization polarimeter or imager based on a superconducting nanowire array. This detector array may find promising application in single-photon polarization detection and imaging.
SOME MORPHOLOGICAL OBSERVATIONS OF CHAROPHYTES (CHARACEAE) FROM BANGLADESH

Morphologically interesting charophytes were found from Chapai-Nawabgonj and Rajshahi districts in Bangladesh. These are: swollen branchlet of Lamprothamnium papulosum (Wallr.) J. Groves, long stalked gametangia and twin antheridia of Nitella hyalina (DC.) Agardh, bifid bract cells of Chara flaccida A. Braun and bifid end cell of Nitellopsis obtusa (Desv.) J. Groves. DOI: http://dx.doi. org/10.3329/jles.v7i0. 20124 J. Life Earth Sci., Vol. 7: 71-77, 2012
Two morphologically distinct groups of the Calypogeia fissa complex were found in Europe

Two morphologically distinct groups of the Calypogeia fissa complex were found in Europe Two genetically distinct groups (PS and PB) detected previously within the C. fissa complex in Europe were studied with respect to 47 morphometric characters. The two examined groups differed statistically significantly with respect to 34 morphological traits. The forward stepwise method of discriminant analysis showed that the set of diagnostic characters could be limited to nine. The best diagnostic features were morphological characters describing the shape of leaf: length and width of leaf, height of dorsal part and distance from the apex to the ventral base of the leaf, length of the 3rd coordinate of the leaf, and underleaf width as well as characters of the stem: length of internodes and size of internode cells. Plants of the PS group were smaller (shoot width range from 922-1780 μm) than plants of the PB group (1600-3900 μm). Based on genetically identified samples, classification functions for each group were computed and the derived functions were used for the classification of samples from the herbarium collections. The principal component analysis and dendrogram constructed on the basis of Euclidean distance, using the set of diagnostic characters, divided the examined samples into two groups that correlated with groups detected by isozyme markers. Results of multivariable analysis showed that it is possible to satisfactorily characterise morphologically both genetically distinct groups of the C. fissa complex.
First report of Bombus terrestris xanthopus Kriechbaumer on the Italian peninsula (Hymenoptera: Apidae)

Abstract A male specimen of Bombus terrestris (L. 1758) showing an intermediate colour between the subspecies xanthopus Kriechbaumer 1870 endemic to Corsica and the subspecies terrestris ubiquitous in the mainland was found within samples collected in 1999 on the Tuscan coast. Hybrid specimens between these subspecies are common on some of the islands of the Tuscan archipelago, while others only have pure populations. The finding is significant as it could signal the spread of the subspecies xanthopus_to the mainland. We consider and discuss the circumstances of the finding.
Isolation and Characterization of Microprotoplasts from Propyzamide-treated Cell Suspension Cultures of Hemerocallis hybrida

To produce intergeneric hybrid plants with one or a few chromosomes via microprotoplast fusion in the Liliaceous ornamentals, we developed a system for isolating microprotoplasts from micronucleated cells in suspension cultures of Hemerocallis hybrida cv. Stella dOro (2n = 2x = 22). Micronucleation was efficiently induced with a micronucleus index up to 19.1 % by the following sequential treatment of suspension cultures: initially with 2 mM hydroxyurea for 24 h and then with 8 μM propyzamide for 60 h with the addition of 20 μM cytochalasin-B to the cultures 20 h after the initiation of the propyzamide treatment. Following the enzyme treatment of the micronucleated cells and ultra-centrifugation with a continuous iso-osmotic gradient of Percoll solution, microprotoplasts were isolated, each of which had a small nucleus surrounded by a thin rim of cytoplasm. Microprotoplasts less than 10 μm in diameter were obtained with yield of 2.9 ×10 4 cells per 1 ml packed cell volume of suspension cells through sequential filtration with nylon sieves with decreasing pore sizes (50, 20 and 10 μm). The DNA content of the microprotoplasts was less than the 2C level as indicated by flow cytometric analysis, and the relative fluorescence intensity in some of their nuclei corresponded to one or a few chromosomes.