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the complex affine quadric $ q ^ { m } = \ { z \ in { \ bbb c } ^ { m + 1 } \ mid z _ { 1 } ^ { 2 } +... + z _ { m + 1 } ^ { 2 } = 1 \ } $ deforms by retraction onto $ s ^ { m } $ ; this allows us to identify $ [ q ^ { k }, q ^ { n } ] $ and $ [ s ^ { k }, s ^ { n } ] = \ pi _ { k } ( s ^ { n } ) $. thus one will say that an element of $ \ pi _ { k } ( s ^ { n } ) $ is complex representable if there exists a complex polynomial map from $ q ^ { k } $ to $ q ^ { n } $ corresponding to this class. in this note we show that $ \ pi _ { n + 1 } ( s ^ { n } ) $ and $ \ pi _ { n + 2 } ( s ^ { n } ) $ are complex representable. | arxiv:math/0702324 |
detection and attribution ( d & a ) studies are cornerstones of climate science, providing crucial evidence for policy decisions. their goal is to link observed climate change patterns to anthropogenic and natural drivers via the optimal fingerprinting method ( ofm ). we show that response theory for nonequilibrium systems offers the physical and dynamical basis for ofm, including the concept of causality used for attribution. our framework clarifies the method ' s assumptions, advantages, and potential weaknesses. we use our theory to perform d & a for prototypical climate change experiments performed on an energy balance model and on a low - resolution coupled climate model. we also explain the underpinnings of degenerate fingerprinting, which offers early warning indicators for tipping points. finally, we extend the ofm to the nonlinear response regime. our analysis shows that ofm has broad applicability across diverse stochastic systems influenced by time - dependent forcings, with potential relevance to ecosystems, quantitative social sciences, and finance, among others. | arxiv:2212.02628 |
studies to hypothesis - generating research which is discovery - based. normally, discovery - based approaches for research are initially hypothesis - free, however, hypothesis testing can be elevated to a new level that effectively supports traditional hypothesis - driven studies. researchers hope that combining integrative analyses of data from a range of different levels can result in new classification approaches to enable personalised interventions. some biologists, such as leroy hood, have suggested that the model of ‘ discovery science ’ is a model which certain research fields are heading towards. for example, it is believed that more information about gene function can be discovered, through the evolution of data - mining tools. discovery - based approaches are often referred to as “ big data ” approaches, because of the large - scale datasets that they involve analyses of. big data includes large - scale homogenous study designs and highly variant datasets, and can be further divided into different kinds of datasets. for example, in neuropsychiatric studies, big data can be categorised as ‘ broad ’ or ‘ deep ’ data. broad data is complex and heterogenous, as it is collected from multiple sources ( e. g., labs and institutions ) and uses different kinds of standards. on the other hand, deep data is collected at multiple levels, e. g., from genes to molecules, cells, circuits, behaviours, and symptoms. broad data allows for population level inferences to be made ; deep data is required for personalised medicine. however, combining broad and deep data and storing them in large - scale databases makes it practically impossible to rely on traditional statistical approaches. instead, the use of discovery - based big data approaches can allow for the generation of hypotheses and offer an analytical tool with high - throughput for pattern recognition and data mining. it is in this way that discovery - based approaches can provide insight into causes and mechanisms of the area of study. although discovery - based and data - driven big data approaches can inform understanding of mechanisms behind the topic of concern, the success of these approaches depends on integrated analyses of the various types of relevant data, and the resultant insight provided. for example, when researching psychiatric dysfunction, it is important to integrate vast and complex data such as brain imaging, genomic data and behavioural data, to uncover any brain - behaviour connections that are relevant to psychiatric dysfunction. therefore, there are challenges to integrating data and developing mining tools. furthermore, validation of results is a big challenge for discovery - based science. although | https://en.wikipedia.org/wiki/Discovery_science |
in recent years, video generation has seen significant advancements. however, challenges still persist in generating complex motions and interactions. to address these challenges, we introduce revision, a plug - and - play framework that explicitly integrates parameterized 3d physical knowledge into a pretrained conditional video generation model, significantly enhancing its ability to generate high - quality videos with complex motion and interactions. specifically, revision consists of three stages. first, a video diffusion model is used to generate a coarse video. next, we extract a set of 2d and 3d features from the coarse video to construct a 3d object - centric representation, which is then refined by our proposed parameterized physical prior model to produce an accurate 3d motion sequence. finally, this refined motion sequence is fed back into the same video diffusion model as additional conditioning, enabling the generation of motion - consistent videos, even in scenarios involving complex actions and interactions. we validate the effectiveness of our approach on stable video diffusion, where revision significantly improves motion fidelity and coherence. remarkably, with only 1. 5b parameters, it even outperforms a state - of - the - art video generation model with over 13b parameters on complex video generation by a substantial margin. our results suggest that, by incorporating 3d physical knowledge, even a relatively small video diffusion model can generate complex motions and interactions with greater realism and controllability, offering a promising solution for physically plausible video generation. | arxiv:2504.21855 |
digital watermark is a commonly used technique to protect the copyright of medias. simultaneously, to increase the robustness of watermark, attacking technique, such as watermark removal, also gets the attention from the community. previous watermark removal methods require to gain the watermark location from users or train a multi - task network to recover the background indiscriminately. however, when jointly learning, the network performs better on watermark detection than recovering the texture. inspired by this observation and to erase the visible watermarks blindly, we propose a novel two - stage framework with a stacked attention - guided resunets to simulate the process of detection, removal and refinement. in the first stage, we design a multi - task network called splitnet. it learns the basis features for three sub - tasks altogether while the task - specific features separately use multiple channel attentions. then, with the predicted mask and coarser restored image, we design refinenet to smooth the watermarked region with a mask - guided spatial attention. besides network structure, the proposed algorithm also combines multiple perceptual losses for better quality both visually and numerically. we extensively evaluate our algorithm over four different datasets under various settings and the experiments show that our approach outperforms other state - of - the - art methods by a large margin. the code is available at http : / / github. com / vinthony / deep - blind - watermark - removal. | arxiv:2012.07007 |
the author revisits the blue bus problem, a famous thought - experiment in law involving probabilistic proof, and presents simple bayesian solutions to different versions of the blue bus hypothetical. in addition, the author expresses his solutions in standard and visual formats, i. e. in terms of probabilities and natural frequencies. | arxiv:1507.05057 |
across the finite temperature transition to the quark - gluon plasma, the qcd topological susceptibility decreases sharply. thus in the high temperature phase the remaining topological objects ( possibly calorons ) form a weakly interacting dilute gas. the overlap dirac operator, through its exact zero modes, allows one to measure the net topological charge. we show that separately the number of positively and negatively charged topological objects can also be extracted from the low end of the overlap dirac spectrum. we find that slightly above the phase transition their number distributions are already consistent with an ideal gas of non - interacting topological objects. | arxiv:1911.10086 |
lecture notes of a block course explaining why quantum field theory might be in a better mathematical state than one gets the impression from the typical introduction to the topic. it is explained how to make sense of a perturbative expansion that fails to converge and how to express feynman loop integrals and their renormalization using the language of distribtions rather than divergent, ill - defined integrals. | arxiv:1201.2714 |
we study finite size and temperature xx0 heisenberg spin chain in weak and strong coupling regimes. by using an elegant connection of the model to integrable combinatorics and probability, we explore and interpret a possible phase structure of the model in asymptotic limit : the limit of large inverse temperature and size. first, partition function and free energy of the model are derived by using techniques and results from random matrix models and nonintersecting brownian motion. we show that, in the asymptotic limit, partition function of the model, written in terms of matrix integral, is governed by the tracy - widom distribution. second, the exact analytic results for the free energy, which is obtained by the asymptotic analysis of the tracy - widom distribution, indicate a completely new and sophisticated phase structure of the model. this phase structure consists of second - and third - order phase transitions. finally, to shed light on our new results, we provide a possible interpretation of the phase structure in terms of dynamical behavior of magnons in the spin chain. we demonstrate distinct features of the phases with schematic spin configurations which have definite features in each region of the phase diagram. | arxiv:1612.03463 |
multi - document grounded dialogue systems ( dgds ) belong to a class of conversational agents that answer users ' requests by finding supporting knowledge from a collection of documents. most previous studies aim to improve the knowledge retrieval model or propose more effective ways to incorporate external knowledge into a parametric generation model. these methods, however, focus on retrieving knowledge from mono - granularity language units ( e. g. passages, sentences, or spans in documents ), which is not enough to effectively and efficiently capture precise knowledge in long documents. this paper proposes re3g, which aims to optimize both coarse - grained knowledge retrieval and fine - grained knowledge extraction in a unified framework. specifically, the former efficiently finds relevant passages in a retrieval - and - reranking process, whereas the latter effectively extracts finer - grain spans within those passages to incorporate into a parametric answer generation model ( bart, t5 ). experiments on dialdoc shared task demonstrate the effectiveness of our method. | arxiv:2302.11849 |
we stress that massive neutrinos may be majorana particles even if the effective mass of the neutrinoless double beta decay m _ ee vanishes. we show that current neutrino oscillation data do allow m _ ee = 0 to hold, if the majorana cp - violating phases lie in two specific regions. strong constraints on three neutrino masses can then be obtained. we find that the neutrino mass spectrum performs a normal hierarchy : m _ 1 < m _ 2 < m _ 3. a possible texture of the neutrino mass matrix is also illustrated under the m _ ee = 0 condition. | arxiv:hep-ph/0305195 |
we briefly review how it is possible to derive some exact expressions for the renormalization constants for the ms - like renormalization prescriptions using the arguments based on the renormalization group. these expressions are obtained for a version of the dimensional technique in which the dimensionful parameter $ \ lambda $ differs from the renormalization scale $ \ mu $. they encode the equations relating the coefficients at higher $ \ varepsilon $ - poles, powers of $ \ ln \ lambda / \ mu $, and mixed terms of the structure $ \ varepsilon ^ { - q } \ ln ^ p \ lambda / \ mu $ to the coefficients of the renormalization group functions ( i. e. of the $ \ beta $ - function and the anomalous dimension ). the general results are verified by some multiloop calculations. | arxiv:2502.12573 |
the paper explores a possible application of the discrete thermodynamics to a 2 - level laser. the model accounts for the laser openness to incoming pumping power and coming out energy with the emitted light. as an open system, a laser should be in open equilibrium with thermodynamic forces, related to both energy flows. conditions of equilibria are expressed by a logistic map with specially developed dynamic inverse pitchfork bifurcation diagrams for graphical presentation of the solutions. the graphs explicitly confirm the triggering nature of a laser where bistability is manifested by pitchfork ground and laser branches, with the relative population equilibrium values close to 1 and 0 correspondingly. simulation was run for a 2 - level laser emitting light from far infrared to short wave uv. a newly discovered feature of such a laser is the line spectrum of up and down transitions of the laser excitable dwellers, occurring between the laser and the ground pitchfork branches beyond bifurcation point. the density of the spectra lines tangibly increases as the branches approach their limits. transitions of both types are overlapping in opposite phases. this effect is a new confirmation of the einstein ' s prohibition on practical realization of a 2 - level laser. wide enough gaps between the lines of the spectra were also discovered in this research. the gaps are shielding the light irradiation and may be considered as potential areas of control over the 2 - level laser emissions. | arxiv:physics/0609044 |
in this paper, we study reinforcement learning from human feedback ( rlhf ) under an episodic markov decision process with a general trajectory - wise reward model. we developed a model - free rlhf best policy identification algorithm, called $ \ mathsf { bsad } $, without explicit reward model inference, which is a critical intermediate step in the contemporary rlhf paradigms for training large language models ( llm ). the algorithm identifies the optimal policy directly from human preference information in a backward manner, employing a dueling bandit sub - routine that constantly duels actions to identify the superior one. $ \ mathsf { bsad } $ adopts a reward - free exploration and best - arm - identification - like adaptive stopping criteria to equalize the visitation among all states in the same decision step while moving to the previous step as soon as the optimal action is identifiable, leading to a provable, instance - dependent sample complexity $ \ tilde { \ mathcal { o } } ( c _ { \ mathcal { m } } sa ^ 3h ^ 3m \ log \ frac { 1 } { \ delta } ) $ which resembles the result in classic rl, where $ c _ { \ mathcal { m } } $ is the instance - dependent constant and $ m $ is the batch size. moreover, $ \ mathsf { bsad } $ can be transformed into an explore - then - commit algorithm with logarithmic regret and generalized to discounted mdps using a frame - based approach. our results show : ( i ) sample - complexity - wise, rlhf is not significantly harder than classic rl and ( ii ) end - to - end rlhf may deliver improved performance by avoiding pitfalls in reward inferring such as overfit and distribution shift. | arxiv:2406.07455 |
a procedure for constructing bound state potentials is given. we show that, under the natural conditions imposed on a radial eigenvalue problem, the only special cases of the general central potential, which are exactly solvable and have infinite number of energy eigenvalues, are the coulomb and harmonic oscillator potentials. | arxiv:quant-ph/9905011 |
spring - like forces on the bridge are key to a banjo ' s characteristic voice. these are due to the tension in strings and head. conceptually distinct from the forces of waves in the strings and head that encode the underlying music, the spring - like forces impact the timbre of how those waves are converted to sound. this note presents a simplified model that allows the head contribution to be calculated ( mostly ) with paper and pencil. the key simplification is placing a circular bridge at the center of the head. the resulting formulae show how design elements and player ' s adjustments can effect the sound. the results also provide estimates of the magnitudes of the effects when evaluated with numerical values for young ' s moduli and typical banjo set - up specs. for steel strings and tight mylar head, the head contribution is about three times as large as that of the strings. | arxiv:2104.06616 |
in its 16 years of scientific measurements, the spitzer space telescope performed a number of ground breaking and key infrared measurements of solar system objects near and far. targets ranged from the smallest planetesimals to the giant planets, and have helped us reform our understanding of these objects while also laying the groundwork for future infrared space - based observations like those to be undertaken by the james webb space telescope in the 2020s. in this first paper, we describe how the spitzer space telescope advanced our knowledge of solar system formation and evolution via observations of small outer solar system planetesimals, i. e., comets, centaurs, and kuiper belt objects ( kbos ). relics from the early formation era of our solar system, these objects hold important information about the processes that created them. the key spitzer observations can be grouped into 3 broad classes : characterization of new solar system objects ( comets d / ison 2012 s1, c / 2016 r2, 1i / ` oumuamua ) ; large population surveys of known object sizes ( comets, centaurs, and kbos ) ; and compositional studies via spectral measurements of body surfaces and emitted materials ( comets, centaurs, and kbos ). | arxiv:2010.13741 |
llr and gpb geodetic precessions have tested flatness for einsten - infeld - hoffmann dynamics of distributed relativistic matter | arxiv:0711.1620 |
in this monograph, we prove an asymptotic approximation for integrals of probability densities over sets in finite dimensional euclidean space, which are far away from the origin ( asymptotic sets ). we use this approximation to investigate tails of quadratic forms of random vectors, supremum of random linear forms among others. applications to the study of finite size random matrices, finite sample statistics of autoregressive processes, and supremum of some stochastic processes. | arxiv:math/0312132 |
in a recent letter, a simple method was proposed to generate solvable models that predict the critical properties of statistical systems in hyperspherical geometries. to that end, it was shown how to reduce a random walk in $ d $ dimensions to an anisotropic one - dimensional random walk on concentric hyperspheres. here, i construct such a random walk to model the adsorption - desorption transition of polymer chains growing near an attractive cylindrical boundary such as that of a cell membrane. i find that the fraction of adsorbed monomers on the boundary vanishes exponentially when the adsorption energy decreases towards its critical value. when the adsorption energy rises beyond a certain value above the critical point whose scale is set by the radius of the cell, the adsorption fraction exhibits a crossover to a linear increase characteristic to polymers growing near planar boundaries. | arxiv:hep-lat/9410023 |
we describe an algorithm for the enumeration of ( candidates of ) vertex - transitive combinatorial $ d $ - manifolds. with an implementation of our algorithm, we determine, up to combinatorial equivalence, all combinatorial manifolds with a vertex - transitive automorphism group on $ n \ leq 13 $ vertices. with the exception of actions of groups of small order, the enumeration is extended to 14 and 15 vertices. | arxiv:math/0506520 |
we present a novel algorithm for implementing owen - scrambling, combining the generation and distribution of the scrambling bits in a single self - contained compact process. we employ a context - free grammar to build a binary tree of symbols, and equip each symbol with a scrambling code that affects all descendant nodes. we nominate the grammar of adaptive regular tiles ( art ) derived from the repetition - avoiding thue - morse word, and we discuss its potential advantages and shortcomings. our algorithm has many advantages, including random access to samples, fixed time complexity, gpu friendliness, and scalability to any memory budget. further, it provides two unique features over known methods : it admits optimization, and it is invertible, enabling screen - space scrambling of the high - dimensional sobol sampler. | arxiv:2311.11664 |
we consider the non - overlapping irreversible random sequential adsorption ( rsa ) process on one - dimensional finite line, which is known also as the car parking process. the probability of each coverage in saturating states is analytically and exactly obtained. in the derivation, a new representation of states in rsa process is introduced, which effectively works to make the calculation clear and simple. | arxiv:0810.5632 |
we present the topology of a volume - limited sample of 11, 884 galaxies, selected from an apparent - magnitude limited sample of over 100, 000 galaxies observed as part of the sloan digital sky survey ( sdss ). the data currently cover three main regions on the sky : one in the galactic north and one in the south, both at zero degrees declination, and one area in the north at higher declination. each of these areas covers a wide range of survey longitude but a narrow range of survey latitude, allowing the two dimensional genus to be measured. the genus curves of the sdss sub - samples are similar, after appropriately normalizing these measurements for the different areas. we sum the genus curves from the three areas to obtain the total genus curve of the sdss. the total curve has a shape similar to the genus curve derived from mock catalogs drawn from the hubble volume lambda cdm simulation and is similar to that of a gaussian random field. likewise, comparison with the genus of the 2dfgrs, after normalization for the difference in area, reveals remarkable similarity in the topology of these samples. we test for the effects of galaxy type segregation by splitting the sdss data into thirds, based on the u ^ * - r ^ * colors of the galaxies, and measure the genus of the reddest and bluest sub - samples. this red / blue split in u ^ * - r ^ * is essentially a split by morphology ( strateva et al. 2001 ). we find that the genus curve for the reddest galaxies exhibits a ` ` meatball ' ' shift of the topology - - reflecting the concentration of red galaxies in high density regions - - compared to the bluest galaxies and the full sample, in agreement with predictions from simulations. | arxiv:astro-ph/0206146 |
we theoretically investigate the two - photon absorption spectrum of conventional s - wave superconductors. the calculation is carried out in the local limit at absolute zero. the direct excitation of quasiparticles is excluded under the condition that the frequency of the external field is lower than twice the magnitude of the superconducting gap. we calculate vertex corrections with the conserving approximation, and show that the amplitude mode is independent of the impurity scattering in the local limit. because of this property, a diverging absorption edge appears in the dirty limit. we propose this behavior as a probe of the amplitude mode. | arxiv:1509.09023 |
we study the dynamic fluctuations of the soft - spin version of the edwards - anderson model in the critical region for $ t \ rightarrow t _ { c } ^ { + } $. first we solve the infinite - range limit of the model using the random matrix method. we define the static and dynamic 2 - point and 4 - point correlation functions at the order $ o ( 1 / n ) $ and we verify that the static limit obtained from the dynamic expressions is correct. in a second part we use the functional integral formalism to define an effective short - range lagrangian $ l $ for the fields $ \ delta q ^ { \ alpha \ beta } _ { i } ( t _ { 1 }, t _ { 2 } ) $ up to the cubic order in the series expansion around the dynamic mean - field value $ \ overline { { q } ^ { \ alpha \ beta } } ( t _ { 1 }, t _ { 2 } ) $. we find the more general expression for the time depending non - local fluctuations, the propagators $ [ \ langle \ delta q ^ { \ alpha \ beta } _ { i } ( t _ { 1 }, t _ { 2 } ) \ delta q ^ { \ alpha \ beta } _ { j } ( t _ { 3 }, t _ { 4 } ) \ rangle _ { \ xi } ] _ { j } $, in the quadratic approximation. finally we compare the long - range limit of the correlations, derived in this formalism, with the correlations of the infinite - range model studied with the previous approach ( random matrices ). | arxiv:cond-mat/9501027 |
the sizes of canvases and stretchers for oil painting have been standardized in france in 19th century and widely accepted in many countries in europe as well as in japan so far. these standard sizes do not follow the golden ratio and porte d ' harmonie number as has been often claimed. in this work, a general formula is derived to calculate the sizes of painting canvases and stretchers, which satisfy exactly the golden ratio and the porte d ' harmonie number as well as the rule for optimal use of material in their mass production. based on this formula new canvas and stretcher sizes are calculated for all three figure, landscape and marine formats. | arxiv:1508.00718 |
rapid variability in the radio flux density of the bl lac object pksb1144 - 379 has been observed at four frequencies, ranging from 1. 5 to 15 ghz, with the vla and the university of tasmania ' s ceduna antenna. intrinsic and line of sight effects were examined as possible causes of this variability, with interstellar scintillation best explaining the frequency dependence of the variability timescales and modulation indices. this scintillation is consistent with a compact source 20 - 40 microarcseconds, or 0. 15 - 0. 3 pc in size. the inferred brightness temperature for pksb1144 - 379 ( assuming that the observed variations are due to scintillation ) is 6. 2e12 k at 4. 9 ghz, with approximately 10 percent of the total flux in the scintillating component. we show that scintillation surveys aimed at identifying variability timescales of days to weeks are an effective way to identify the agn with the highest brightness temperatures. | arxiv:1206.6914 |
we report on the high resolution photoassociation spectroscopy of a $ ^ { 87 } $ rb spin - 1 bose - einstein condensate to the $ 1 _ \ mathrm { g } ( p _ { 3 / 2 } ) v = 152 $ excited molecular states. we demonstrate the use of spin dependent photoassociation to experimentally identify the molecular states and their corresponding initial scattering channel. these identifications are in excellent agreement with the eigenvalues of a hyperfine - rotational hamiltonian. using the observed spectra we estimate the change in scattering length and identify photoassociation laser light frequency ranges that maximize the change in the spin - dependent mean - field interaction energy. | arxiv:0806.3464 |
aligning multiple protein structures can yield valuable information about structural similarities among related proteins, as well as provide insight into evolutionary relationships between proteins in a family. we have developed an algorithm ( mstali ) for aligning multiple protein structures using biochemical and biophysical properties, including torsion angles, secondary structure, hydrophobicity, and surface accessibility. the algorithm is a progressive alignment algorithm motivated by popular techniques from multiple sequence alignment. it has demonstrated success in aligning the major structural regions of a set of proteins from the s / r kinase family. the algorithm was also successful at aligning functional residues of these proteins. in addition, the algorithm was also successful in aligning seven members of the acyl carrier protein family, including both experimentally derived as well as computationally modeled structures. | arxiv:1911.02406 |
recently, we had numerically shown that, for a non - minimal coupling that is a simple power of the scale factor, scale invariant magnetic fields arise in a class of bouncing universes. in this work, we { \ it analytically } evaluate the spectrum of magnetic and electric fields generated in a sub - class of such models. we illustrate that, for cosmological scales which have wavenumbers much smaller than the wavenumber associated with the bounce, the shape of the spectrum is preserved across the bounce. using the analytic solutions obtained, we also illustrate that the problem of backreaction is severe at the bounce. finally, we show that the power spectrum of the magnetic field remains invariant under a two parameter family of transformations of the non - minimal coupling function. | arxiv:1604.02143 |
this study investigated the magnetic field ( $ h $ ) dependence of thermal conductivity ( $ \ kappa $ ) in type i ( pb ) and type ii ( nb ) superconductors. the $ \ kappa $ of nb displayed hysteresis, showing a local minimum during increasing $ h $ process but not during decreasing $ h $ process. different magnetic field dependencies were observed in pb with varying purity : $ \ kappa $ of 3n - pb exhibited broad hysteresis, while that of 5n - pb showed hysteresis similar to 3n - nb. | arxiv:2311.00937 |
), bioengineering / biotechnology, nuclear technology, advanced materials ( e. g., graphene ), the scramjet and drones ( along with railguns and high - energy laser beams for military uses ), superconductivity, the memristor, and green technologies such as alternative fuels ( e. g., fuel cells, self - driving electric and plug - in hybrid cars ), augmented reality devices and wearable electronics, artificial intelligence, and more efficient and powerful leds, solar cells, integrated circuits, wireless power devices, engines, and batteries. large hadron collider, the largest single machine ever built, was constructed between 1998 and 2008. the understanding of particle physics is expected to expand with better instruments including larger particle accelerators such as the lhc and better neutrino detectors. dark matter is sought via underground detectors and observatories like ligo have started to detect gravitational waves. genetic engineering technology continues to improve, and the importance of epigenetics on development and inheritance has also become increasingly recognized. new spaceflight technology and spacecraft are also being developed, like the boeing ' s orion and spacex ' s dragon 2. new, more capable space telescopes, such as the james webb space telescope which was launched to orbit in december, 2021, and the colossus telescope, have been designed. the international space station was completed in the 2000s, and nasa and esa plan a human mission to mars in the 2030s. the variable specific impulse magnetoplasma rocket ( vasimr ) is an electro - magnetic thruster for spacecraft propulsion and is expected to be tested in 2015. the breakthrough initiatives project plans to send the first ever spacecraft to visit another star, which will consist of numerous super - light chips driven by electric propulsion in the 2030s, and receive images of the proxima centauri system, along with, possibly, the potentially habitable planet proxima centauri b, by midcentury. 2004 saw the first crewed commercial spaceflight when mike melvill crossed the boundary of space on june 21, 2004. = = by type = = = = = biotechnology = = = timeline of agriculture and food technology timeline of biotechnology = = = civil engineering = = = civil engineering architecture and building construction bridges, harbors, tunnels, dams surveying, instruments and maps, cartography, urban engineering, water supply and sewerage = = = communication = = = = = = computing = = = = = = consumer technology = | https://en.wikipedia.org/wiki/History_of_technology |
several uniform asymptotics expansions of the weber parabolic cylinder functions are considered, one group in terms of elementary functions, another group in terms of airy functions. starting point for the discussion are asymptotic expansions given earlier by f. w. j. olver. some of his results are modified to improve the asymptotic properties and to enlarge the intervals for using the expansions in numerical algorithms. olver ' s results are obtained from the differential equation of the parabolic cylinder functions ; we mention how modified expansions can be obtained from integral representations. numerical tests are given for three expansions in terms of elementary functions. in this paper only real values of the parameters will be considered. | arxiv:math/0109188 |
we propose here a multiplex network approach to investigate simultaneously different types of dependency in complex data sets. in particular, we consider multiplex networks made of four layers corresponding respectively to linear, non - linear, tail, and partial correlations among a set of financial time series. we construct the sparse graph on each layer using a standard network filtering procedure, and we then analyse the structural properties of the obtained multiplex networks. the study of the time evolution of the multiplex constructed from financial data uncovers important changes in intrinsically multiplex properties of the network, and such changes are associated with periods of financial stress. we observe that some features are unique to the multiplex structure and would not be visible otherwise by the separate analysis of the single - layer networks corresponding to each dependency measure. | arxiv:1606.04872 |
we study the properties of the bose polaron, an impurity strongly interacting with a bose - einstein condensate, using a field - theoretic approach and make predictions for the spectral function and various quasiparticle properties that can be tested in experiment. we find that most of the spectral weight is contained in a coherent attractive and a metastable repulsive polaron branch. we show that the qualitative behavior of the bose polaron is well described by a non - selfconsistent t - matrix approximation by comparing analytical results to numerical data obtained from a fully selfconsistent t - matrix approach. the latter takes into account an infinite number of bosons excited from the condensate. | arxiv:1308.3457 |
reinforcement learning ( rl ) provides a naturalistic framing for learning through trial and error, which is appealing both because of its simplicity and effectiveness and because of its resemblance to how humans and animals acquire skills through experience. however, real - world embodied learning, such as that performed by humans and animals, is situated in a continual, non - episodic world, whereas common benchmark tasks in rl are episodic, with the environment resetting between trials to provide the agent with multiple attempts. this discrepancy presents a major challenge when attempting to take rl algorithms developed for episodic simulated environments and run them on real - world platforms, such as robots. in this paper, we aim to address this discrepancy by laying out a framework for autonomous reinforcement learning ( arl ) : reinforcement learning where the agent not only learns through its own experience, but also contends with lack of human supervision to reset between trials. we introduce a simulated benchmark earl around this framework, containing a set of diverse and challenging simulated tasks reflective of the hurdles introduced to learning when only a minimal reliance on extrinsic intervention can be assumed. we show that standard approaches to episodic rl and existing approaches struggle as interventions are minimized, underscoring the need for developing new algorithms for reinforcement learning with a greater focus on autonomy. | arxiv:2112.09605 |
cellulose disassembly is an important issue in designing nanostructures using cellulose - based materials. in this work, we present a joint of experimental and theoretical study addressing the disassembly of cellulose nanofibrils. through 2, 2, 6, 6 - tetramethylpiperidine - 1 - oxyl ( tempo ) mediated oxidation processes, combined with atomic force microscopy results, we find the formation of nanofibers with diameters corresponding to a single cellulose polymer chain. the formation of these polymer chains is ruled by repulsive electrostatic interactions between the oxidized chains. further first - principles calculations have been done in order to provide an atomistic understanding the cellulose disassembling processes, focusing on the balance of the interchain and intersheet interactions upon oxidation. firstly we analyse these interaction in pristine systems, where we found the intersheet interaction stronger than the interchain one. in the oxidized systems, we have considered the formation of ( charged ) carboxylate groups along the inner sites of elementary fibrils. we show a net charge concentration on the carboxylate groups, supporting the emergence of repulsive electrostatic interactions between the cellulose nanofibers. indeed, our total energy results show that the weakening of the binding strength between the fibrils is proportional to the concentration and the net charge density of the carboxylate group. moreover, by comparing interchain and intersheet binding energies, we found that most of the disassembly processes should take place by breaking the interchain o - - h $ \ cdots $ o hydrogen bond interactions, and thus supporting the experimental observation of single and double cellulose polymeric chains. | arxiv:2010.15686 |
fluorescence resonance energy transfer ( fret ) from individual, dye - labeled rna molecules confined in freely - diffusing attoliter - volume aqueous droplets is carefully compared to fret from unconfined rna in solution. the use of freely - diffusing droplets is a remarkably simple and high - throughput technique that facilitates a substantial increase in signal - to - noise for single - molecular - pair fret measurements. we show that there can be dramatic differences between fret in solution and in droplets, which we attribute primarily to an altered ph in the confining environment. we also demonstrate that a sufficient concentration of a non - ionic surfactant mitigates this effect and restores fret to its neutral - ph solution value. at low surfactant levels, even accounting for ph, we observe differences between the distribution of fret values in solution and in droplets which remain unexplained. our results will facilitate the use of nanoemulsion droplets as attoliter volume reactors for use in biophysical and biochemical assays, and also in applications such as protein crystallization or nanoparticle synthesis, where careful attention to the ph of the confined phase is required. | arxiv:1312.0854 |
increasing experimental and theoretical evidence points towards a dual nature of the 5 $ f $ electrons in actinide - based strongly correlated metallic compounds, with some 5 $ f $ electrons being localized and others delocalized. in a recent paper ( prb xxx, 2004 ), we suggested the interplay of intra - atomic correlations as described by hund ' s rules and a weakly anisotropic hopping ( hybridization ) as a possible mechanism. the purpose of the present work is to provide a first step towards a microscopic description of partial localization in solids by analyzing how well various approximation schemes perform when applied to small clusters. it is found that many aspects of partial localization are described appropriately both by a variational wavefunction of gutzwiller type and by a treatment which keeps only those interactions which are present in lda + u calculations. in contrast, the energies and phase diagram calculated within the hartree fock approximation show little resemblence with the exact results. enhancement of hopping anisotropy by hund ' s rule correlations are found in all approximations. | arxiv:cond-mat/0402124 |
we report on the serendipitous discovery of an unprecedented interaction between the radio lobe of a radio galaxy and a spiral galaxy. the discovery was made thanks to lofar observations at 144 mhz of the galaxy cluster abell 160 ( $ z = 0. 04317 $ ) provided by the lofar two - metre sky survey. the new low - frequency observations revealed that one of the radio plumes of the central galaxy gin 049 overlaps with the spiral galaxy jo36. previous studies carried out with muse revealed that the warm ionized gas in the disk of jo36, traced by the h $ \ alpha $ emission, is severely truncated with respect to the stellar disk. we further explore this unique system by including new ugmrt observations at 675 mhz to map the spectral index. the emerging scenario is that jo36 has interacted with the radio plume in the past 200 - 500 myr. the encounter resulted in a positive feedback event for jo36 in the form of a star formation rate burst of $ \ sim14 $ $ m _ \ odot $ yr $ ^ { - 1 } $. in turn, the galaxy passage left a trace in the radio - old plasma by re - shaping the old relativistic plasma via magnetic draping. | arxiv:2309.02002 |
bilevel optimization has recently attracted considerable attention due to its abundant applications in machine learning problems. however, existing methods rely on prior knowledge of problem parameters to determine stepsizes, resulting in significant effort in tuning stepsizes when these parameters are unknown. in this paper, we propose two novel tuning - free algorithms, d - tfbo and s - tfbo. d - tfbo employs a double - loop structure with stepsizes adaptively adjusted by the " inverse of cumulative gradient norms " strategy. s - tfbo features a simpler fully single - loop structure that updates three variables simultaneously with a theory - motivated joint design of adaptive stepsizes for all variables. we provide a comprehensive convergence analysis for both algorithms and show that d - tfbo and s - tfbo respectively require $ o ( \ frac { 1 } { \ epsilon } ) $ and $ o ( \ frac { 1 } { \ epsilon } \ log ^ 4 ( \ frac { 1 } { \ epsilon } ) ) $ iterations to find an $ \ epsilon $ - accurate stationary point, ( nearly ) matching their well - tuned counterparts using the information of problem parameters. experiments on various problems show that our methods achieve performance comparable to existing well - tuned approaches, while being more robust to the selection of initial stepsizes. to the best of our knowledge, our methods are the first to completely eliminate the need for stepsize tuning, while achieving theoretical guarantees. | arxiv:2410.05140 |
correlated sources are present in communication systems where protocols ensure that there is some predetermined information for sources. here correlated sources across an eavesdropped channel that incorporate a heterogeneous encoding scheme and their effect on the information leakage when some channel information and a source have been wiretapped is investigated. the information leakage bounds for the slepian - wolf scenario are provided. thereafter, the shannon cipher system approach is presented. further, an implementation method using a matrix partition approach is described. | arxiv:1501.04478 |
we calculate the mass spectrum and the structure of the positronium system at a strong coupling in a basis light - front approach. we start from the light - front qed hamiltonian and retain one dynamical photon in our basis. we perform the fermion mass renormalization associated with the nonperturbative fermion self - energy correction. we present the resulting mass spectrum and wave functions for the selected low - lying states. next, we apply this approach to qcd and calculate the heavy meson system with one dynamical gluon retained. we illustrate the obtained mass spectrum and wave functions for the selected low - lying states. | arxiv:2103.06719 |
we generalize a special case of a theorem of proctor on the enumeration of lozenge tilings of a hexagon with a maximal staircase removed, using kuo ' s graphical condensation method. additionally, we prove a formula for a weighted version of the given region. the result also extends work of ciucu and fischer. by applying the factorization theorem of ciucu, we are also able to generalize a special case of macmahon ' s boxed plane partition formula. | arxiv:1510.04486 |
as a point defect with unique spin and optical properties, nitrogen - vacancy ( nv ) center in diamond has attracted much attention in the fields of quantum sensing, quantum simulation, and quantum networks. the optical properties of an nv center are crucial for all these quantum applications. however, nv centers fabricated by destructive methods such as electron irradiation or ion implantation usually exhibit poor optical coherence. in this work, we demonstrate a non - destructive method to fabricate optically coherent nv centers. high - purity single crystal diamonds are annealed under high pressure and high temperature ( 1700 $ ^ { \ circ } $ c, 5. 5 gpa ), and individually resolvable nv centers with narrow ple linewidth ( < 100 mhz ) are produced. the high - pressure condition prevents the conversion of diamond to graphite during high - temperature annealing, significantly expanding the parameter space for creating high - performance artificial defects for quantum information science. these findings deepen our understanding of nv center formation in diamond and have implications for the optimization of color centers in solids, including silicon carbide and hexagonal boron nitride. | arxiv:2409.17442 |
in coalitional games, a player $ i $ is regarded as strictly more desirable than player $ j $ if substituting $ j $ with $ i $ within any coalition leads to a strict augmentation in the value of certain coalitions, while preserving the value of the others. we adopt a property - driven approach to ' integrate ' the notion of the desirability relation into a total relation by establishing sets of independent axioms leading to the characterization of solutionconcepts from the related literature. we focus on social ranking solutions consistent with the desirability relation and propose complementary sets of properties for the axiomatic characterization of five existing solutions : ceteris paribus ( cp - ) majority, lexicographic excellence ( lex - cel ), dual - lex, $ l ^ { ( 1 ) } $ solution and its dual version $ l ^ { ( 1 ) } _ { * } $. these characterizations reveal additional similarities among the five solutions and emphasize the essential characteristics that should be taken into account when selecting a social ranking. a practical scenario involving a bicameral legislature is studied. | arxiv:2404.18755 |
edge computing pushes the cloud computing boundaries beyond uncertain network resource by leveraging computational processes close to the source and target of data. time - sensitive and data - intensive video surveillance applications benefit from on - site or near - site data mining. in recent years, many smart video surveillance approaches are proposed for object detection and tracking by using artificial intelligence ( ai ) and machine learning ( ml ) algorithms. however, it is still hard to migrate those computing and data - intensive tasks from cloud to edge due to the high computational requirement. in this paper, we envision to achieve intelligent surveillance as an edge service by proposing a hybrid lightweight tracking algorithm named kerman ( kernelized kalman filter ). kerman is a decision tree based hybrid kernelized correlation filter ( kcf ) algorithm proposed for human object tracking, which is coupled with a lightweight convolutional neural network ( l - cnn ) for high performance. the proposed kerman algorithm has been implemented on a couple of single board computers ( sbc ) as edge devices and validated using real - world surveillance video streams. the experimental results are promising that the kerman algorithm is able to track the object of interest with a decent accuracy at a resource consumption affordable by edge devices. | arxiv:1808.02134 |
the purpose of my phd thesis is to investigate different group theoretical and geometrical aspects of supergravity theories. to this aim, several research topics are explored : on one side, the construction of supergravity models in diverse space - time dimensions, including the study of boundary contributions, and the disclosure of the hidden gauge structure of these theories ; on the other side, the analysis of the algebraic links among different superalgebras related to supergravity theories. in the first three chapters, we give a general introduction and furnish the theoretical background necessary for a clearer understanding of the thesis. we then move to the original results of my phd research activity : we start from the development of the so called $ ads $ - lorentz supergravity in $ d = 4 $ by adopting the so called rheonomic approach and discuss on boundary contributions to the theory. subsequently, we focus on the analysis of the hidden gauge structure of supersymmetric free differential algebras. more precisely, we concentrate on the hidden superalgebras underlying $ d = 11 $ and $ d = 7 $ supergravities, exploring the symmetries hidden in the theories and the physical role of the nilpotent fermionic generators naturally appearing in the aforementioned superalgebras. after that, we move to the pure algebraic and group theoretical description of ( super ) algebras, focusing on new analytic formulations of the so called $ s $ - expansion method. the final chapter contains the summary of the results of my doctoral studies presented in the thesis and possible future developments. in the appendices, we collect notation, useful formulas, and detailed calculations. | arxiv:1802.06602 |
the fractal shape and multi - component nature of the interstellar medium together with its vast range of dynamical scales provides one of the great challenges in theoretical and numerical astrophysics. here we will review recent progress in the direct modelling of interstellar hydromagnetic turbulence, focusing on the role of energy injection by supernova explosions. the implications for dynamo theory will be discussed in the context of the mean - field approach. results obtained with the test field - method are confronted with analytical predictions and estimates from quasilinear theory. the simulation results enforce the classical understanding of a turbulent galactic dynamo and, more importantly, yield new quantitative insights. the derived scaling relations enable confident global mean - field modelling. | arxiv:1101.3976 |
we study the angular dependence of the flux from partially synchrotron self - absorbed conical jets ( proposed by blandford \ & k { \ " o } nigl ). we consider the jet viewed from either a side or close to on axis, and in the latter case, either from the jet top or bottom. we derive analytical formulae for the flux in each of these cases, and find the exact solution for an arbitrary angle numerically. we find that the maximum of the emission occurs when the jet is viewed from top on - axis, which is contrast to a previous result, which found the maximum at some intermediate angle and null emission on - axis. we then calculate the ratio of the jet - to - counterjet emission for this model, which depends on the viewing angle and the index of power - law electrons. we apply our results to the black - hole binary cyg x - 1. given the jet - to - counterjet flux ratio of $ \ gtrsim $ 50 found observationally and the current estimates of the inclination, we find the jet velocity to be $ \ gtrsim 0. 8c $. we also point out that when the projection effect is taken into account, the radio observations imply the jet half - opening angle of $ \ lesssim 1 ^ { \ rm o } $, a half of the value given before. when combined with the existing estimates of $ \ gamma _ { \ rm j } $, the jet half - opening angle is low, $ \ ll 1 / \ gamma _ { \ rm j } $, and much lower than values observed in blazars, unless $ \ gamma _ { \ rm j } $ is much higher than currently estimated. | arxiv:1606.03428 |
we show how the flat spacetime galileon field theories ( fsgft ) in arbitrary dimensions can be obtained through a born - infeld type structure. this construction involves a brane metric and non - linear combinations of derivatives of a scalar field. our setup gives rise to some galileon tensors and vectors useful for the variational analysis which are related to the momentum density of the probe lovelock branes floating in a $ n $ - dimensional flat bulk. we find further that the noether currents associated to these galileon theories may be written in terms of such tensors. | arxiv:1503.01564 |
we study the process of mass segregation through 2 - body relaxation in galactic nuclei with a central massive black hole ( mbh ). this study has bearing on a variety of astrophysical questions, from the distribution of x - ray binaries at the galactic centre, to tidal disruptions of main - sequence and giant stars, to inspirals of compact objects into the mbh, an important category of events for the future space borne gravitational wave interferometer lisa. in relatively small galactic nuclei, typical hosts of mbhs with masses in the range 1e4 - 1e7 msun, the relaxation induces the formation of a steep density cusp around the mbh and strong mass segregation. using a spherical stellar dynamical monte - carlo code, we simulate the long - term relaxational evolution of galactic nucleus models with a spectrum of stellar masses. our focus is the concentration of stellar black holes to the immediate vicinity of the mbh. special attention is given to models developed to match the conditions in the milky way nucleus. | arxiv:astro-ph/0607001 |
the discovery of correlated insulating states in moir \ ' e heterostructures has renewed the interest in strongly - coupled electron systems where spin and valley ( or layer ) degrees of freedom are intertwined. in the strong - coupling limit, such systems can be effectively described by su ( 4 ) spin - valley models akin to kugel - khomskii models long studied in the context of spin - orbit coupled materials. however, typical moir \ ' e heterostructures also exhibit interactions that break the su ( 4 ) symmetry down to su ( 2 ) $ { } _ { \ mathrm { spin } } \ otimes $ u ( 1 ) $ { } _ { \ mathrm { valley } } $. here we investigate the impact of such symmetry - breaking couplings on the magnetic phase diagram for triangular superlattices considering a filling of two electrons ( or holes ) per moir \ ' e unit cell. we explore a broad regime of couplings - - including xxz anisotropies, dzyaloshinskii - moriya exchange and on - site hund ' s couplings - - using semi - classical monte carlo simulations. we find a multitude of classically ordered phases, including ( anti - ) ferromagnetic, incommensurate, and stripe order, manifesting in different sectors of the spin - valley model ' s parameter space. zooming in on the regimes where quantum fluctuations are likely to have an effect, we employ pseudo - fermion functional renormalization group ( pf - frg ) calculations to resolve quantum disordered ground states such as spin - valley liquids, which we indeed find for certain parameter regimes. as a concrete example, we discuss the case of trilayer graphene aligned with hexagonal boron nitride using material - specific parameters. | arxiv:2303.01244 |
this paper investigates the problem of decentralized resource allocation in the presence of byzantine attacks. such attacks occur when an unknown number of malicious agents send random or carefully crafted messages to their neighbors, aiming to prevent the honest agents from reaching the optimal resource allocation strategy. we characterize these malicious behaviors with the classical byzantine attacks model, and propose a class of byzantine - resilient decentralized resource allocation algorithms augmented with dual - domain defenses. the honest agents receive messages containing the ( possibly malicious ) dual variables from their neighbors at each iteration, and filter these messages with robust aggregation rules. theoretically, we prove that the proposed algorithms can converge to neighborhoods of the optimal resource allocation strategy, given that the robust aggregation rules are properly designed. numerical experiments are conducted to corroborate the theoretical results. | arxiv:2310.05698 |
morrow - jones and witt have shown that generic spatial topologies admit initial data that evolve to locally de sitter spacetimes under einstein ' s equations. we simplify their arguments, make them a little more general, and solve for the global time evolution of the wormhole initial data considered by them. finally we give explicit examples of locally de sitter domains of development whose universal covers cannot be embedded in de sitter space. | arxiv:gr-qc/9906040 |
let $ \ boldsymbol { b } _ { \ omega } ^ { \ mathscr { f } } $ be the bicyclic semigroup extension for the family $ \ mathscr { f } $ of $ { \ omega } $ - closed subsets of $ \ omega $ which is introduced in \ cite { gutik - mykhalenych = 2020 }. we study topologizations of the semigroup $ \ boldsymbol { b } _ { \ omega } ^ { \ mathscr { f } } $ for the family $ \ mathscr { f } $ of inductive $ { \ omega } $ - closed subsets of $ \ omega $. we generalize eberhart - selden and bertman - west results about topologizations of the bicyclic semigroup \ cite { bertman - west - 1976, eberhart - selden = 1969 } and show that every hausdorff shift - continuous topology on the semigroup $ \ boldsymbol { b } _ { \ omega } ^ { \ mathscr { f } } $ is discrete and if a hausdorff semitopological semigroup $ s $ contains $ \ boldsymbol { b } _ { \ omega } ^ { \ mathscr { f } } $ as a proper dense subsemigroup then $ s \ setminus \ boldsymbol { b } _ { \ omega } ^ { \ mathscr { f } } $ is an ideal of $ s $. also, we prove the following dichotomy : every hausdorff locally compact shift - continuous topology on $ \ boldsymbol { b } _ { \ omega } ^ { \ mathscr { f } } $ with an adjoined zero is either compact or discrete. as a consequence of the last result we obtain that every hausdorff locally compact semigroup topology on $ \ boldsymbol { b } _ { \ omega } ^ { \ mathscr { f } } $ with an adjoined zero is discrete and every hausdorff locally compact shift - continuous topology on the semigroup $ \ boldsymbol { b } _ { \ omega } ^ { \ mathscr { f } } \ sqcup i $ with an adjoined compact ideal $ i $ is either compact or the ideal $ i $ is open, which extent many results about locally compact top | arxiv:2212.05522 |
robotic wire arc additive manufacturing ( waam ) is a metal additive manufacturing technology, offering flexible 3d printing while ensuring high quality near - net - shape final parts. however, waam also suffers from geometric imprecision, especially for low - melting - point metal such as aluminum alloys. in this paper, we present a multi - robot framework for waam process monitoring and control. we consider a three - robot setup : a 6 - dof welding robot, a 2 - dof trunnion platform, and a 6 - dof sensing robot with a wrist - mounted laser line scanner measuring the printed part height profile. the welding parameters, including the wire feed rate, are held constant based on the materials used, so the control input is the robot path speed. the measured output is the part height profile. the planning phase decomposes the target shape into slices of uniform height. during runtime, the sensing robot scans each printed layer, and the robot path speed for the next layer is adjusted based on the deviation from the desired profile. the adjustment is based on an identified model correlating the path speed to change in height. the control architecture coordinates the synchronous motion and data acquisition between all robots and sensors. using a three - robot waam testbed, we demonstrate significant improvements of the closed loop scan - n - print approach over the current open loop result on both a flat wall and a more complex turbine blade shape. | arxiv:2411.15915 |
long - context modeling is crucial for next - generation language models, yet the high computational cost of standard attention mechanisms poses significant computational challenges. sparse attention offers a promising direction for improving efficiency while maintaining model capabilities. we present nsa, a natively trainable sparse attention mechanism that integrates algorithmic innovations with hardware - aligned optimizations to achieve efficient long - context modeling. nsa employs a dynamic hierarchical sparse strategy, combining coarse - grained token compression with fine - grained token selection to preserve both global context awareness and local precision. our approach advances sparse attention design with two key innovations : ( 1 ) we achieve substantial speedups through arithmetic intensity - balanced algorithm design, with implementation optimizations for modern hardware. ( 2 ) we enable end - to - end training, reducing pretraining computation without sacrificing model performance. as shown in figure 1, experiments show the model pretrained with nsa maintains or exceeds full attention models across general benchmarks, long - context tasks, and instruction - based reasoning. meanwhile, nsa achieves substantial speedups over full attention on 64k - length sequences across decoding, forward propagation, and backward propagation, validating its efficiency throughout the model lifecycle. | arxiv:2502.11089 |
we summarise some basic issues relevant to the optimisation and design of space - based experiments for the observation of the extensive air showers produced by ultra - high energy cosmic particles interacting with the atmosphere. a number of basic relations is derived and discussed with a twofold goal : defining requirements for the experimental apparatus and estimating the exptected performance. | arxiv:0810.5711 |
the field of autonomous driving has attracted considerable interest in approaches that directly infer 3d objects in the bird ' s eye view ( bev ) from multiple cameras. some attempts have also explored utilizing 2d detectors from single images to enhance the performance of 3d detection. however, these approaches rely on a two - stage process with separate detectors, where the 2d detection results are utilized only once for token selection or query initialization. in this paper, we present a single model termed simpb, which simultaneously detects 2d objects in the perspective view and 3d objects in the bev space from multiple cameras. to achieve this, we introduce a hybrid decoder consisting of several multi - view 2d decoder layers and several 3d decoder layers, specifically designed for their respective detection tasks. a dynamic query allocation module and an adaptive query aggregation module are proposed to continuously update and refine the interaction between 2d and 3d results, in a cyclic 3d - 2d - 3d manner. additionally, query - group attention is utilized to strengthen the interaction among 2d queries within each camera group. in the experiments, we evaluate our method on the nuscenes dataset and demonstrate promising results for both 2d and 3d detection tasks. our code is available at : https : / / github. com / nullmax - vision / simpb. | arxiv:2403.10353 |
we report a proof - of - concept demonstration of a quantum order - finding algorithm for factoring the integer 21. our demonstration involves the use of a compiled version of the quantum phase estimation routine, and builds upon a previous demonstration by mart \ ' in - l \ ' { o } pez et al. in nature photonics 6, 773 ( 2012 ). we go beyond this work by using a configuration of approximate toffoli gates with residual phase shifts, which preserves the functional correctness and allows us to achieve a complete factoring of n = 21. we implemented the algorithm on ibm quantum processors using only 5 qubits and successfully verified the presence of entanglement between the control and work register qubits, which is a necessary condition for the algorithm ' s speedup in general. the techniques we employ may be useful in carrying out shor ' s algorithm for larger integers, or other algorithms in systems with a limited number of noisy qubits. | arxiv:2103.13855 |
let $ g $ be a directed graph such that the in - degree of any vertex $ g $ is at least one. let also $ { \ mathcal { \ tau } } : v ( g ) \ rightarrow \ bbb { n } $ be an assignment of thresholds to the vertices of $ g $. a subset $ m $ of vertices of $ g $ is called a dynamic monopoly for $ ( g, \ tau ) $ if the vertex set of $ g $ can be partitioned into $ d _ 0 \ cup... \ cup d _ t $ such that $ d _ 0 = m $ and for any $ i \ geq 1 $ and any $ v \ in d _ i $, the number of edges from $ d _ 0 \ cup... \ cup d _ { i - 1 } $ to $ v $ is at least $ \ tau ( v ) $. one of the most applicable and widely studied threshold assignments in directed graphs is strict majority threshold assignment in which for any vertex $ v $, $ \ tau ( v ) = \ lceil ( deg ^ { in } ( v ) + 1 ) / 2 \ rceil $, where $ deg ^ { in } ( v ) $ stands for the in - degree of $ v $. by a strict majority dynamic monopoly of a graph $ g $ we mean any dynamic monopoly of $ g $ with strict majority threshold assignment for the vertices of $ g $. in this paper we first discuss some basic upper and lower bounds for the size of dynamic monopolies with general threshold assignments and then obtain some hardness complexity results concerning the smallest size of dynamic monopolies in directed graphs. next we show that any directed graph on $ n $ vertices and with positive minimum in - degree admits a strict majority dynamic monopoly with $ n / 2 $ vertices. we show that this bound is achieved by a polynomial time algorithm. this upper bound improves greatly the best known result. the final note of the paper deals with the possibility of the improvement of the latter $ n / 2 $ bound. | arxiv:1212.3682 |
for a $ k $ - tree $ t $, we prove that the maximum local mean order is attained in a $ k $ - clique of degree $ 1 $ and that it is not more than twice the global mean order. we also bound the global mean order if $ t $ has no $ k $ - cliques of degree $ 2 $ and prove that for large order, the $ k $ - star attains the minimum global mean order. these results solve the remaining problems of stephens and oellermann [ j. graph theory 88 ( 2018 ), 61 - 79 ] concerning the mean order of sub - $ k $ - trees of $ k $ - trees. | arxiv:2309.16545 |
in this paper, the authors investigate the deep sea treasure ( dst ) problem as proposed by vamplew et al. through a number of proofs, the authors show the original dst problem to be quite basic, and not always representative of practical multi - objective optimization problems. in an attempt to bring theory closer to practice, the authors propose an alternative, improved version of the dst problem, and prove that some of the properties that simplify the original dst problem no longer hold. the authors also provide a reference implementation and perform a comparison between their implementation, and other existing open - source implementations of the problem. finally, the authors also provide a complete pareto - front for their new dst problem. | arxiv:2110.06742 |
we have fabricated hybrid magnetic complexes from v atoms and tetracyanoethylene ( tcne ) ligands via atomic manipulation with a cryogenic scanning tunneling microscope. using tunneling spectroscopy we observe spin - polarized molecular orbitals as well as kondo behavior. for complexes having two v atoms, the kondo behavior can be quenched for different molecular arrangements, even as the spin - polarized orbitals remain unchanged. this is explained by variable spin - spin ( i. e., v - v ) ferromagnetic coupling through a single tcne molecule, as supported by density functional calculations. | arxiv:0907.0490 |
the rapid evolution of large language models ( llms ) has transformed them from basic conversational tools into sophisticated entities capable of complex reasoning and decision - making. these advancements have led to the development of specialized llm - based agents designed for diverse tasks such as coding and web browsing. as these agents become more capable, the need for a robust framework that facilitates global communication and collaboration among them towards advanced objectives has become increasingly critical. distributed agents in a worldwide network ( dawn ) addresses this need by offering a versatile framework that integrates llm - based agents with traditional software systems, enabling the creation of agentic applications suited for a wide range of use cases. dawn enables distributed agents worldwide to register and be easily discovered through gateway agents. collaborations among these agents are coordinated by a principal agent equipped with reasoning strategies. dawn offers three operational modes : no - llm mode for deterministic tasks, copilot for augmented decision - making, and llm agent for autonomous operations. additionally, dawn ensures the safety and security of agent collaborations globally through a dedicated safety, security, and compliance layer, protecting the network against attackers and adhering to stringent security and compliance standards. these features make dawn a robust network for deploying agent - based applications across various industries. | arxiv:2410.22339 |
we consider the problem of rational uncertainty about unproven mathematical statements, remarked on by g \ " odel and others. using bayesian - inspired arguments we build a normative model of fair bets under deductive uncertainty which draws from both probability and the theory of algorithms. we comment on connections to zeilberger ' s notion of " semi - rigorous proofs ", particularly that inherent subjectivity would be present. we also discuss a financial view with models of arbitrage where traders have limited computational resources. | arxiv:1708.09032 |
we investigate the topological zeta function for unimodal maps in general and dynamical zeta functions for the tent map in particular. for the generic situation, when the kneading sequence is aperiodic, it is shown that the zeta functions have a natural boundary along its radius of convergence, beyond which the function lacks analytic continuation. we make a detailed study of the function $ \ prod _ { n = 0 } ^ { \ infty } ( 1 - z ^ { 2 ^ n } ) $ associated with sequences of period doublings. it is demonstrated that this function has a dense set of poles and zeros on the unit circle, exhibiting a rich number theoretical structure. | arxiv:chao-dyn/9606004 |
we study the chaotic behavior of the synchronization phase transition in the kuramoto model. we discuss the relationship with analogous features found in the hamiltonian mean field ( hmf ) model. our numerical results support the connection between the two models, which can be considered as limiting cases ( dissipative and conservative, respectively ) of a more general dynamical system of damped - driven coupled pendula. we also show that, in the kuramoto model, the shape of the phase transition and the largest lyapunov exponent behavior are strongly dependent on the distribution of the natural frequencies. | arxiv:0807.1870 |
some types of medical and topographic imaging device produce images in which the pixel values are " phase - wrapped ", i. e. measured modulus a known scalar. phase unwrapping can be viewed as the problem of inferring the number of shifts between each and every pair of neighboring pixels, subject to an a priori preference for smooth surfaces, and subject to a zero curl constraint, which requires that the shifts must sum to 0 around every loop. we formulate phase unwrapping as a mean field inference problem in a markov network, where the prior favors the zero curl constraint. we compare our mean field technique with the least squares method on a synthetic 100x100 image, and give results on a 512x512 synthetic aperture radar image from sandia national laboratories. < long text > | arxiv:1301.2252 |
the magnetic field distribution in the vortex state of yni2b2c has been probed by muon spin rotation ( musr ). the analysis based on the london model with nonlocal corrections shows that the vortex lattice has changed from hexagonal to square with increasing magnetic field h. at low fields the vortex core radius, rho _ v ( h ), decreases with increasing h much steeper than what is expected from the sqrt ( h ) behavior of the sommerfeld constant gamma ( h ), strongly suggesting that the anomaly in gamma ( h ) primarily arises from the quasiparticle excitations outside the vortex cores. | arxiv:cond-mat/0201038 |
this paper proposes a novel load frequency control ( lfc ) approach formulated on an optimal structure of the coefficient diagram method ( cdm ) in a two - area thermal power system. as part of a realistic analysis, nonlinearities related to governor dead band ( gdb ) and generation rate constraint ( grc ) have been considered. in this article, a hybrid cdm method is combined with the optimization of its mathematical equations to achieve an innovative controller. furthermore, a new metaheuristic optimization technique called the water cycle algorithm ( wca ) is used to determine the optimal coefficients of the cdm controller. for the purpose of demonstrating the validity of the proposed scheme, a wide range of uncertainties in the dynamic parameters of a nonlinear power system were tested. in addition, a comparative study is presented between the results obtained from a classical integral, cdm alone, optimized fuzzy, optimized pid, and the suggested controller. in this new approach to improved control, algebraic support provides a robust and responsive controller that can provide fast and stable dynamic responses and effectively overcome the detrimental effects of nonlinearities and uncertainties in the parameters of the power system. | arxiv:2208.07054 |
in this work, we present an analytical study on the surface plasmon polaritons in a two dimensional parity anomaly chern insulator. the connections between the topology in the bulk implied by the bhz model and the dispersion relations of the surface plasmons have been revealed. anisotropy has been considered during the calculations of the dispersion relations which allows different permittivities perpendicular to the conductive plane. two surface plasmon modes each contains two branches of dispersion relations have been found. the topologically non - trivial case gives quite different hall conductivities compared with the trivial one, which leads to significant modifications of the dispersion curves or even the absence of particular branch of the surface plasmons. our investigations pave a possible way for the detection of the parity anomaly in a two - dimensional chern insulator via plasmonic responses. | arxiv:2305.09554 |
it has been shown that for a certain special type of quantum graphs the random - matrix form factor can be recovered to at least third order in the scaled time \ tau using periodic - orbit theory. two types of contributing pairs of orbits were identified, those which require time - reversal symmetry and those which do not. we present a new technique of dealing with contribution from the former type of orbits. the technique allows us to derive the third order term of the expansion for general graphs. although the derivation is rather technical, the advantages of the technique are obvious : it makes the derivation tractable, it identifies explicitly the orbit configurations which give the correct contribution, it is more algorithmical and more system - independent, making possible future applications of the technique to systems other than quantum graphs. | arxiv:nlin/0305009 |
energy is in general not conserved for mechanical nonholonomic systems with affine constraints. in this article we point out that, nevertheless, in certain cases, there is a modification of the energy that is conserved. such a function coincides with the energy of the system relative to a different reference frame, in which the constraint is linear. after giving sufficient conditions for this to happen, we point out the role of symmetry in this mechanism. lastly, we apply these ideas to prove that the motions of a heavy homogeneous solid sphere that rolls inside a convex surface of revolution in uniform rotation about its vertical figure axis, are ( at least for certain parameter values and in open regions of the phase space ) quasi - periodic on tori of dimension up to three. | arxiv:1503.06661 |
the vast integration of non - synchronous renewable energy sources compromises power system stability, increasing vulnerability to frequency deviations due to the lack of inertia. current efforts to decarbonise electricity grids while maintaining frequency security still rely on ancillary services ( as ) provision, such as inertia and frequency response, from flexible synchronous generators, placing these type of units in an advantageous position in the as market. however, in the ongoing transition to decarbonisation, not enough attention has been given to analysing market power in the frequency - containment as market. this work presents a strategic bidding model designed to analyse market power in the coupled energy and frequency - containment as market. through a non - convex primal - dual bi - level formulation, we determine the interaction of a strategic market player with the rest of the market that behaves competitively. the case study is based on great britain in 2030, demonstrating the capacity of the strategic player to influence prices. while this impact is perceived in the energy market, it is particularly pronounced in the as market. | arxiv:2412.09181 |
in this paper we present a fully relativistic approach to modelling both the continuum emission and the reflected fluorescent iron line from a primary x - ray source near a kerr black hole. the x - ray source is located above an accretion disc orbiting around the black hole. the source is assumed to be a static point source located on an arbitrary position above the disc, on or off the axis of rotation. we carry out monte carlo simulations in order to estimate the iron line spectrum as well as its equivalent width. because of the gravitational lensing effect, an enhancement of the iron line is expected when the primary source is located close to the central black hole. we find that for a source located on the axis of rotation the enhancement is relatively modest. an observer at inclination 30 degrees would measure an equivalent width of ~ 300ev in the extreme case of a maximally rotating black hole and a source located at height 1. 5 gravitational radius from the centre. this corresponds to an equivalent width enhancement factor of about 2 compared to the classical value where no lensing effect comes into play. however, when allowing the source to be located off the axis of rotation, much stronger enhancement can be obtained. in the extreme case of a maximally rotating black hole and a source located just above the approaching side of the disc, an observer at inclination 30d egrees could measure an equivalent width as high as ~ 1. 5 kev ( i. e. ~ 10 times the classical value ). we also find that observers located at high inclination angles observe a stronger line than observers at low inclination angles. | arxiv:astro-ph/0005020 |
we study the direct and inverse scattering problems for the zakharov - shabat system. representations for the jost solutions are obtained in the form of the power series in terms of a transformed spectral parameter. in terms of that parameter, the jost solutions are convergent power series in the unit disk. the coefficients of the series are computed following a simple recurrent integration procedure. this essentially reduces the solution of the direct scattering problem to the computation of the coefficients and location of zeros of an analytic function inside of the unit disk. the solution of the inverse scattering problem reduces to the solution of a system of linear algebraic equations for the power series coefficients, while the potential is recovered from the first coefficient. the overall approach leads to a simple and efficient method for the numerical solution of both direct and inverse scattering problems, which is illustrated by numerical examples. | arxiv:2505.02169 |
a new super - exceptional embedding construction of the heterotic m5 - brane ' s sigma - model was recently shown to produce, at leading order in the super - exceptional vielbein components, the super - nambu - goto ( green - schwarz - type ) lagrangian for the embedding fields plus the perry - schwarz lagrangian for the free abelian self - dual higher gauge field. beyond that, further fields and interactions emerge in the model, arising from probe m2 - and probe m5 - brane wrapping modes. here we classify the full super - exceptional field content and work out some of its characteristic interactions from the rich super - exceptional lagrangian of the model. we show that su ( 2 ) xu ( 1 ) - valued scalar and vector fields emerge from probe m2 - and m5 - branes wrapping the vanishing cycle in the a _ 1 - type singularity ; together with a pair of spinor fields of u ( 1 ) - hypercharge + - 1 and each transforming as su ( 2 ) iso - doublets. then we highlight the appearance of a wzw - type term in the super - exceptional ps - lagrangian and find that on the electromagnetic field it gives the first - order non - linear dbi - correction, while on the iso - vector scalar field it has the form characteristic of the coupling of vector mesons to pions via the skyrme baryon current. we discuss how this is suggestive of a form of su ( 2 ) - flavor chiral hadrodynamics emerging on the single ( n = 1 ) m5 brane, different from, but akin to, holographic large - $ n $ qcd. | arxiv:2006.00012 |
finite volume schemes often have difficulties to resolve the low mach number ( incompressible ) limit of the euler equations. incompressibility is only non - trivial in multiple spatial dimensions. low mach fixes, however generally are applied to the one - dimensional method and the method is then used in a dimensionally split way. this often reduces its stability. here, it is suggested to keep the one - dimensional method as it is, and only to extend it to multiple dimensions in a particular, all - speed way. this strategy is found to lead to much more stable numerical methods. apart from the conceptually pleasing property of modifying the scheme only when it becomes necessary, the multi - dimensional all - speed extension also does not include any free parameters or arbitrary functions, which generally are difficult to choose, or might be problem dependent. the strategy is exemplified on a lagrange projection method and on a relaxation solver. | arxiv:2103.02621 |
heavy charged bosons, with masses in the range of a few tev, are a characteristic of warped extra - dimensional models with bulk gauge fields. rendering the latter consistent with electroweak precision tests typically requires either a deformation of the metric or extension of the gauge symmetry. we make here the first attempt at finding empirical discriminants which would tell these models apart. demonstrating the power of simple kinematic observables involving same - sign leptons, we construct simple yet powerful statistical discriminants. | arxiv:1811.02231 |
we posit that the distinct patterns observed in fermion masses and mixings are due to a minimally broken $ \ mathrm { u } ( 2 ) _ { q + e } $ flavor symmetry acting on left - handed quarks and right - handed charged leptons, giving rise to an accidental $ \ mathrm { u } ( 2 ) ^ 5 $ symmetry at the renormalizable level without imposing selection rules on the weinberg operator. we show that the symmetry can be consistently gauged by explicit examples and comment on realizations in $ \ mathrm { su } ( 5 ) $ unification. via a model - independent smeft analysis, we find that selection rules due to $ \ mathrm { u } ( 2 ) _ { q + e } $ enhance the importance of charged lepton flavor violation as a probe, where significant experimental progress is expected in the near future. | arxiv:2311.09288 |
we consider the problem of private membership aggregation ( pma ), in which a user counts the number of times a certain element is stored in a system of independent parties that store arbitrary sets of elements from a universal alphabet. the parties are not allowed to learn which element is being counted by the user. further, neither the user nor the other parties are allowed to learn the stored elements of each party involved in the process. pma is a generalization of the recently introduced problem of $ k $ private set intersection ( $ k $ - psi ). the $ k $ - psi problem considers a set of $ m $ parties storing arbitrary sets of elements, and a user who wants to determine if a certain element is repeated at least at $ k $ parties out of the $ m $ parties without learning which party has the required element and which party does not. to solve the general problem of pma, we dissect it into four categories based on the privacy requirement and the collusions among databases / parties. we map these problems into equivalent private information retrieval ( pir ) problems. we propose achievable schemes for each of the four variants of the problem based on the concept of cross - subspace alignment ( csa ). the proposed schemes achieve \ emph { linear } communication complexity as opposed to the state - of - the - art $ k $ - psi scheme that requires \ emph { exponential } complexity even though our pma problems contain more security and privacy constraints. | arxiv:2309.03872 |
blind motion deblurring is one of the most basic and challenging problems in image processing and computer vision. it aims to recover a sharp image from its blurred version knowing nothing about the blur process. many existing methods use maximum a posteriori ( map ) or expectation maximization ( em ) frameworks to deal with this kind of problems, but they cannot handle well the figh frequency features of natural images. most recently, deep neural networks have been emerging as a powerful tool for image deblurring. in this paper, we prove that encoder - decoder architecture gives better results for image deblurring tasks. in addition, we propose a novel end - to - end learning model which refines generative adversarial network by many novel training strategies so as to tackle the problem of deblurring. experimental results show that our model can capture high frequency features well, and the results on benchmark dataset show that proposed model achieves the competitive performance. | arxiv:1901.01641 |
during the last couple of decades, the use of arrays of bolometers has represented one of the leading techniques for the search for rare events. cuore, an array of 988 teo $ _ 2 $ bolometers that is taking data since april 2017 at the laboratori nazionali del gran sasso ( italy ), exploits the large mass, low background, good energy resolution and low energy threshold of these detectors successfully. thanks to these characteristics, they could be also sensitive to other low energy rare processes, such as galactic dark matter interactions. in this paper we describe the data acquisition system that was developed for the cuore experiment. thanks to its high modularity, the data acquisition here described has been used in different setups with similar requirements, including the pilot experiment cuore - 0 and the demonstrator for the next phase of the project, cupid - 0, also taking data at lngs. | arxiv:1807.11446 |
new, simple models of ` ` black hole interiors ' ', namely spherically symmetric solutions of the einstein field equations in matter matching the schwarzschild vacuum at spacelike hypersurfaces ` ` r < 2m ' ' are constructed. the models satisfy the weak energy condition and their matter content is specified by an equation of state of the elastic type. | arxiv:gr-qc/9706083 |
social science researchers are generally accustomed to treating ordinal variables as though they are continuous. in this paper, we consider how identification constraints in ordinal factor analysis can mimic the treatment of ordinal variables as continuous. we describe model constraints that lead to latent variable predictions equaling the average of ordinal variables. this result leads us to propose minimal identification constraints, which we call " integer constraints, " that center the latent variables around the scale of the observed, integer - coded ordinal variables. the integer constraints lead to intuitive model parameterizations because researchers are already accustomed to thinking about ordinal variables as though they are continuous. we provide a proof that our proposed integer constraints are indeed minimal identification constraints, as well as an illustration of how integer constraints work with real data. we also provide simulation results indicating that integer constraints are similar to other identification constraints in terms of estimation convergence and admissibility. | arxiv:2501.06094 |
we describe the software requirements and development methodology developed for the nlc control system. given the longevity of that project, and the likely geographical distribution of the collaborating engineers, the planned requirements management process is somewhat more formal than the norm in high energy physics projects. the short term goals of the requirements process are to accurately estimate costs, to decompose the problem, and to determine likely technologies. the long term goal is to enable a smooth transition from high level functional requirements to specific subsystem and component requirements for individual programmers, and to support distributed development. the methodology covers both ends of that life cycle. it covers both the analytical and documentary tools for software engineering, and project management support. | arxiv:physics/0111161 |
parameter inference with an estimated covariance matrix systematically loses information due to the remaining uncertainty of the covariance matrix. here, we quantify this loss of precision and develop a framework to hypothetically restore it, which allows to judge how far away a given analysis is from the ideal case of a known covariance matrix. we point out that it is insufficient to estimate this loss by debiasing a fisher matrix as previously done, due to a fundamental inequality that describes how biases arise in non - linear functions. we therefore develop direct estimators for parameter credibility contours and the figure of merit. we apply our results to des science verification weak lensing data, detecting a 10 % loss of information that increases their credibility contours. no significant loss of information is found for kids. for a euclid - like survey, with about 10 nuisance parameters we find that 2900 simulations are sufficient to limit the systematically lost information to 1 %, with an additional uncertainty of about 2 %. without any nuisance parameters 1900 simulations are sufficient to only lose 1 % of information. we also derive an estimator for the fisher matrix of the unknown true covariance matrix, two estimators of its inverse with different physical meanings, and an estimator for the optimally achievable figure of merit. the formalism here quantifies the gains to be made by running more simulated datasets, allowing decisions to be made about numbers of simulations in an informed way. | arxiv:1609.00504 |
new large deviations results that characterize the asymptotic information rates for general $ d $ - dimensional ( $ d $ - d ) stationary gaussian fields are obtained. by applying the general results to sensor nodes on a two - dimensional ( 2 - d ) lattice, the asymptotic behavior of ad hoc sensor networks deployed over correlated random fields for statistical inference is investigated. under a 2 - d hidden gauss - markov random field model with symmetric first order conditional autoregression and the assumption of no in - network data fusion, the behavior of the total obtainable information [ nats ] and energy efficiency [ nats / j ] defined as the ratio of total gathered information to the required energy is obtained as the coverage area, node density and energy vary. when the sensor node density is fixed, the energy efficiency decreases to zero with rate $ \ theta ( { area } ^ { - 1 / 2 } ) $ and the per - node information under fixed per - node energy also diminishes to zero with rate $ o ( n _ t ^ { - 1 / 3 } ) $ as the number $ n _ t $ of network nodes increases by increasing the coverage area. as the sensor spacing $ d _ n $ increases, the per - node information converges to its limit $ d $ with rate $ d - \ sqrt { d _ n } e ^ { - \ alpha d _ n } $ for a given diffusion rate $ \ alpha $. when the coverage area is fixed and the node density increases, the per - node information is inversely proportional to the node density. as the total energy $ e _ t $ consumed in the network increases, the total information obtainable from the network is given by $ o ( \ log e _ t ) $ for the fixed node density and fixed coverage case and by $ \ theta ( e _ t ^ { 2 / 3 } ) $ for the fixed per - node sensing energy and fixed density and increasing coverage case. | arxiv:0903.1496 |
on today ' s internet, combining the end - to - end security of tls with content delivery networks ( cdns ) while ensuring the authenticity of connections results in a challenging delegation problem. when cdn servers provide content, they have to authenticate themselves as the origin server to establish a valid end - to - end tls connection with the client. in standard tls, the latter requires access to the secret key of the server. to curb this problem, multiple workarounds exist to realize a delegation of the authentication. in this paper, we present a solution that renders key sharing unnecessary and reduces the need for workarounds. by adapting identity - based signatures to this setting, our solution offers short - lived delegations. additionally, by enabling forward - security, existing delegations remain valid even if the server ' s secret key leaks. we provide an implementation of the scheme and discuss integration into a tls stack. in our evaluation, we show that an efficient implementation incurs less overhead than a typical network round trip. thereby, we propose an alternative approach to current delegation practices on the web. | arxiv:2009.02137 |
this article presents an overview of the main gamification projects for digital libraries, either for tagging or ocr correction. this overview is followed by a state of the art with functionalities, motivations, sociology of contributors and the scope of gamification compared to the serious games and explicit crowdsourcing. finally a comparison of results between explicit crowdsourcing and gamification is proposed. [ english title : digital libraries and gamification : overview and state of the art ] | arxiv:1512.08395 |
we study electron heating in collisionless current - driven turbulence due to the nonlinear interactions between electron - and ion - acoustic waves. pic simulation results show that due to a large difference between the electron and ion mean velocities the buneman instability excites large - amplitude ion - acoustic waves, which strongly modifies the electron velocity distribution function, leading to a secondary instability that generates fast electron - acoustic waves ; and in this process, a giant electron hole is ultimately created. this giant electron hole is responsible for strong electron heating due to phase mixing. the numerical simulation results are consistent with the previous observations and provide insight into the key processes responsible for electron heating and the generation of nonlinear waves in a collisionless current - driven instability. | arxiv:2208.00614 |
in this paper, the t - channel charged higgs production at lhc is studied. production process is a t - channel single top event with charged higgs exchange. therefore the signal is similar with standard model single top production in terms of the final state. in the first step, the signal cross section is calculated and compared to the other main production processes which are used for a heavy charged higgs search at lhc, i. e., pp - > tbh - and pp - > h + - > tb. in the next step, an event generation and analysis is applied on signal and background events, in order to estimate the signal significance. the signal cross section is typically smaller than the associated production ( tbh - ) and resonance production ( tb ) by a factor of 10 - 3 and ranges from 10 fb to 1 fb for charged higgs mass from 200 to 500 gev at tanbeta = 50. due to the small cross section of signal events and large sm background, the signal significance is small even after a dedicated kinematic analysis and selection of events, however, tanbeta values above 120 can be excluded at an integrated luminosity of 3000 fb - 1. | arxiv:1506.06949 |
we provide a novel local definition for spectrally flowed vertex operators in the sl ( 2, $ \ mathbb { r } $ ) - wzw model, generalising the proposal of maldacena and ooguri in [ arxiv : hep - th / 0111180 ] for the singly - flowed case to all $ \ omega > 1 $. this allows us to establish the precise connection between the computation of correlators using the so - called spectral flow operator, and the methods introduced recently by dei and eberhardt in [ arxiv : 2105. 12130 ] based on local ward identities. we show that the auxiliary variable $ y $ used in the latter paper arises naturally from a point - splitting procedure in the space - time coordinate. the recursion relations satisfied by spectrally flowed correlators, which take the form of partial differential equations in $ y $ - space, then correspond to null - state conditions for generalised spectral flowed operators. we highlight the role of the sl ( 2, $ \ mathbb { r } $ ) series identifications in this context, and prove the validity of the conjecture put forward in [ arxiv : 2105. 12130 ] for $ y $ - space structure constants of three - point functions with arbitrary spectral flow charges. | arxiv:2208.00978 |
we propose hyperdynamics, a dynamics meta - learning framework that conditions on an agent ' s interactions with the environment and optionally its visual observations, and generates the parameters of neural dynamics models based on inferred properties of the dynamical system. physical and visual properties of the environment that are not part of the low - dimensional state yet affect its temporal dynamics are inferred from the interaction history and visual observations, and are implicitly captured in the generated parameters. we test hyperdynamics on a set of object pushing and locomotion tasks. it outperforms existing dynamics models in the literature that adapt to environment variations by learning dynamics over high dimensional visual observations, capturing the interactions of the agent in recurrent state representations, or using gradient - based meta - optimization. we also show our method matches the performance of an ensemble of separately trained experts, while also being able to generalize well to unseen environment variations at test time. we attribute its good performance to the multiplicative interactions between the inferred system properties - - captured in the generated parameters - - and the low - dimensional state representation of the dynamical system. | arxiv:2103.09439 |
active debris removal ( adr ) missions have garnered significant interest as means of mitigating collision risks in space. this work proposes a convex optimization - based model predictive control ( mpc ) approach to provide guidance for such missions. while convex optimization can obtain optimal solutions in polynomial time, it relies on the successive convexification of nonconvex dynamics, leading to inaccuracies. here, the need for successive convexification is eliminated by using near - linear generalized equinoctial orbital elements ( geqoe ) and by updating the reference trajectory through a new split - edelbaum approach. the solution accuracy is then measured relative to a high - fidelity dynamics model, showing that the mpc - convex method can generate accurate solutions without iterations. | arxiv:2308.08783 |
the extent to which a sequence of finite length differs from a shifted version of itself is measured by its aperiodic autocorrelations. of particular interest are sequences whose entries are 1 or - 1, called binary sequences, and sequences whose entries are complex numbers of unit magnitude, called unimodular sequences. since the 1950s, there is sustained interest in sequences with small aperiodic autocorrelations relative to the sequence length. one of the main motivations is that a sequence with small aperiodic autocorrelations is intrinsically suited for the separation of signals from noise, and therefore has natural applications in digital communications. this survey reviews the state of knowledge concerning the two central problems in this area : how small can the aperiodic autocorrelations of a binary or a unimodular sequence collectively be and how can we efficiently find the best such sequences? since the analysis and construction of sequences with small aperiodic autocorrelations is closely tied to the ( often much easier ) analysis of periodic autocorrelation properties, several fundamental results on corresponding problems in the periodic setting are also reviewed. | arxiv:1602.03722 |
we present versions of ergodic theorems for $ l _ 1 $ - - $ l _ \ infty $ contractions in banach - - kantorovich $ l _ p $ - lattices associated with the maharam measure taking values in the algebra of measurable functions. | arxiv:1306.3827 |
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