text stringlengths 1 3.65k | source stringlengths 15 79 |
|---|---|
distributed as an open source library since 2013, rtab - map started as an appearance - based loop closure detection approach with memory management to deal with large - scale and long - term online operation. it then grew to implement simultaneous localization and mapping ( slam ) on various robots and mobile platforms. as each application brings its own set of contraints on sensors, processing capabilities and locomotion, it raises the question of which slam approach is the most appropriate to use in terms of cost, accuracy, computation power and ease of integration. since most of slam approaches are either visual or lidar - based, comparison is difficult. therefore, we decided to extend rtab - map to support both visual and lidar slam, providing in one package a tool allowing users to implement and compare a variety of 3d and 2d solutions for a wide range of applications with different robots and sensors. this paper presents this extended version of rtab - map and its use in comparing, both quantitatively and qualitatively, a large selection of popular real - world datasets ( e. g., kitti, euroc, tum rgb - d, mit stata center on pr2 robot ), outlining strengths and limitations of visual and lidar slam configurations from a practical perspective for autonomous navigation applications. | arxiv:2403.06341 |
ultrafast techniques have emerged as promising methods to study and control quantum materials. to maintain the quantum nature of the systems under study, excess heating must be avoided. in this work, we demonstrate a method that employs the nonequilibrium laser excitation of planar stretching optical phonons in tetragonal systems to quench an electronic nematic state across a quantum phase transition. appropriately tuned off - resonant pulses can perform a quantum quench of the system either into the nematic phase ( red detuning ) or out of it ( blue detuning ). the nonlinear coupling of this phonon mode to nematicity not only mediates interactions in the nematic channel, but it also suppresses heating effects. we illustrate the applicability of our general results by considering the microscopic parameters of the nematic unconventional superconductor fese. | arxiv:1809.05600 |
we consider the problem of classifying trajectories generated by dynamical systems. we investigate a model - based approach, the common approach in control engineering, and a data - driven approach based on support vector machines, a popular method in the area of machine learning. the analysis points out connections between the two approaches and their relative merits. | arxiv:1803.10552 |
we consider the linear quadratic ( lq ) optimal control problem for a class of evolution equations in infinite dimensions, in the presence of distributed and nonlocal inputs. following the perspective taken in our previous research work on the lq problem for integro - differential equations, where the memory term - - here involving the control actions - - is seen as a component of the state, we offer a full ( closed - loop, riccati - like ) solution to the optimization problem. | arxiv:2407.15559 |
to scale non - parametric extensions of probabilistic topic models such as latent dirichlet allocation to larger data sets, practitioners rely increasingly on parallel and distributed systems. in this work, we study data - parallel training for the hierarchical dirichlet process ( hdp ) topic model. based upon a representation of certain conditional distributions within an hdp, we propose a doubly sparse data - parallel sampler for the hdp topic model. this sampler utilizes all available sources of sparsity found in natural language - an important way to make computation efficient. we benchmark our method on a well - known corpus ( pubmed ) with 8m documents and 768m tokens, using a single multi - core machine in under four days. | arxiv:1906.02416 |
signed by john albion andrew, the governor of massachusetts, on april 10, 1861. rogers, a geologist who had recently arrived in boston from the university of virginia, wanted to establish an institution to address rapid scientific and technological advances. he did not wish to found a professional school, but a combination with elements of both professional and liberal education, proposing that : the true and only practicable object of a polytechnic school is, as i conceive, the teaching, not of the minute details and manipulations of the arts, which can be done only in the workshop, but the inculcation of those scientific principles which form the basis and explanation of them, and along with this, a full and methodical review of all their leading processes and operations in connection with physical laws. the rogers plan reflected the german research university model, emphasizing an independent faculty engaged in research, as well as instruction oriented around seminars and laboratories. = = = early developments = = = two days after mit was chartered, the first battle of the civil war broke out. after a long delay through the war years, mit ' s first classes were held in the mercantile building in boston in 1865. the new institute was founded as part of the morrill land - grant colleges act to fund institutions " to promote the liberal and practical education of the industrial classes " and was a land - grant school. in 1863 under the same act, the commonwealth of massachusetts founded the massachusetts agricultural college, which developed as the university of massachusetts amherst. in 1866, the proceeds from land sales went toward new buildings in the back bay. mit was informally called " boston tech ". the institute adopted the european polytechnic university model and emphasized laboratory instruction from an early date. despite chronic financial problems, the institute saw growth in the last two decades of the 19th century under president francis amasa walker. programs in electrical, chemical, marine, and sanitary engineering were introduced, new buildings were built, and the size of the student body increased to more than one thousand. the curriculum drifted to a vocational emphasis, with less focus on theoretical science. the fledgling school still suffered from chronic financial shortages which diverted the attention of the mit leadership. during these " boston tech " years, mit faculty and alumni rebuffed harvard university president ( and former mit faculty ) charles w. eliot ' s repeated attempts to merge mit with harvard college ' s lawrence scientific school. there would be at least six attempts to absorb mit into harvard. in its cramped back bay location, mit could not afford to expand its overcrowded facilities, driving | https://en.wikipedia.org/wiki/Massachusetts_Institute_of_Technology |
we present a systematic comparison of doubly charged higgs boson production mechanisms at hadron colliders in the context of the type ii seesaw model, emphasizing the importance of higher - order corrections and subdominant channels. we consider the drell - yan channel at next - to - leading order in qcd, photon fusion at leading order, gluon fusion with resummation of threshold logarithms up to next - to - next - to - next - to - leading logarithmic accuracy, and same - sign weak boson fusion at next - to - leading order in qcd. for drell - yan processes, we study the impact of a static jet veto at next - to - leading order matched to the resummation of jet veto scale logarithms at next - to - next - to - leading logarithmic accuracy. for the photon fusion channel, the dependence on modeling photon parton distribution functions is definitively assessed. to model vector boson fusion at next - to - leading order, we include all interfering topologies at $ \ mathcal { o } ( \ alpha ^ 4 ) $ and propose a method for introducing generator - level cuts within the mc @ nlo formalism. our results are obtained using a monte carlo tool chain linking the \ textsc { feynrules }, \ textsc { nloct } and \ textsc { madgraph5 \ _ amc @ nlo } programs and have necessitated the development of new, publicly available, universal feynrules output libraries that encode the interactions between the type ii seesaw scalars and standard model particles. libraries are compatible with both the normal and inverted ordering of majorana neutrino masses. | arxiv:1912.08975 |
deep neural networks ( dnn ) have revolutionized the field of natural language processing ( nlp ). convolutional neural network ( cnn ) and recurrent neural network ( rnn ), the two main types of dnn architectures, are widely explored to handle various nlp tasks. cnn is supposed to be good at extracting position - invariant features and rnn at modeling units in sequence. the state of the art on many nlp tasks often switches due to the battle between cnns and rnns. this work is the first systematic comparison of cnn and rnn on a wide range of representative nlp tasks, aiming to give basic guidance for dnn selection. | arxiv:1702.01923 |
motivated by the important work of brown adn york on quasilocal energy, we propose definitions of quasilocal energy and momentum surface energy of a spacelike 2 - surface with positive intrinsic curvature in a spacetime. we show that the quasilocal energy of the boundary of a compact spacelike hypersurface which satisfies the local energy condition is strictly positive unless the spacetime is flat along the spacelike hypersurface. | arxiv:gr-qc/0303019 |
although routinely utilized in literature, orthogonal waveforms may lose orthogonality in distributed multi - input multi - output ( mimo ) radar with spatially separated transmit ( tx ) and receive ( rx ) antennas, as the waveforms may experience distinct delays and doppler frequency offsets unique to different tx - rx propagation paths. in such cases, the output of each waveform - specific matched filter ( mf ), employed to unravel the waveforms at the rxs, contains both an \ auto term and multiple cross terms, i. e., the filtered response of the desired and, respectively, undesired waveforms. we consider the impact of non - orthogonal waveforms and their cross terms on target detection with or without timing, frequency, and phase errors. to this end, we present a general signal model for distributed mimo radar, examine target detection using existing coherent / non - coherent detectors and two new detectors, including a hybrid detector that requires phase coherence locally but not across distributed antennas, and provide a statistical analysis leading to closed - form expressions of false alarm and detection probabilities for all detectors. our results show that cross terms can behave like foes or allies, respectively, if they and the auto term add destructively or constructively, depending on the propagation delay, frequency, and phase offsets. regarding sync errors, we show that phase errors affect only coherent detectors, frequency errors degrade all but the non - coherent detector, while all are impacted by timing errors, which result in a loss in the signal - to - noise ratio ( snr ). | arxiv:2102.09719 |
we find a description of hybrid inflation in ( 3 + 1 ) - dimensions using brane dynamics of hanany - witten type. p - term inflation / acceleration of the universe with the hybrid potential has a slow - roll de sitter stage and a waterfall stage which leads towards an n = 2 supersymmetric ground state. we identify the slow - roll stage of inflation with a non - supersymmetric ` coulomb phase ' with fayet - iliopoulos term. this stage ends when the mass squared of one of the scalars in the hypermultiplet becomes negative. at that moment the brane system starts undergoing a phase transition via tachyon condensation to a fully higgsed supersymmetric vacuum which is the absolute ground state of p - term inflation. a string theory / cosmology dictionary is provided, which leads to constraints on parameters of the brane construction from cosmological experiments. we display a splitting of mass levels reminiscent of the zeeman effect due to spontaneous supersymmetry breaking. | arxiv:hep-th/0110271 |
according to the gottesman - knill theorem, a class of quantum circuits, namely the so - called stabilizer circuits, can be simulated efficiently on a classical computer. we introduce a new algorithm for this task, which is based on the graph - state formalism. it shows significant improvement in comparison to an existing algorithm, given by gottesman and aaronson, in terms of speed and of the number of qubits the simulator can handle. we also present an implementation. | arxiv:quant-ph/0504117 |
remote sensing of the earth ' s surface water is critical in a wide range of environmental studies, from evaluating the societal impacts of seasonal droughts and floods to the large - scale implications of climate change. consequently, a large literature exists on the classification of water from satellite imagery. yet, previous methods have been limited by 1 ) the spatial resolution of public satellite imagery, 2 ) classification schemes that operate at the pixel level, and 3 ) the need for multiple spectral bands. we advance the state - of - the - art by 1 ) using commercial imagery with panchromatic and multispectral resolutions of 30 cm and 1. 2 m, respectively, 2 ) developing multiple fully convolutional neural networks ( fcn ) that can learn the morphological features of water bodies in addition to their spectral properties, and 3 ) fcn that can classify water even from panchromatic imagery. this study focuses on rivers in the arctic, using images from the quickbird, worldview, and geoeye satellites. because no training data are available at such high resolutions, we construct those manually. first, we use the rgb, and nir bands of the 8 - band multispectral sensors. those trained models all achieve excellent precision and recall over 90 % on validation data, aided by on - the - fly preprocessing of the training data specific to satellite imagery. in a novel approach, we then use results from the multispectral model to generate training data for fcn that only require panchromatic imagery, of which considerably more is available. despite the smaller feature space, these models still achieve a precision and recall of over 85 %. we provide our open - source codes and trained model parameters to the remote sensing community, which paves the way to a wide range of environmental hydrology applications at vastly superior accuracies and 2 orders of magnitude higher spatial resolution than previously possible. | arxiv:2212.13613 |
facial expression editing is a challenging task as it needs a high - level semantic understanding of the input face image. in conventional methods, either paired training data is required or the synthetic face resolution is low. moreover, only the categories of facial expression can be changed. to address these limitations, we propose an expression generative adversarial network ( exprgan ) for photo - realistic facial expression editing with controllable expression intensity. an expression controller module is specially designed to learn an expressive and compact expression code in addition to the encoder - decoder network. this novel architecture enables the expression intensity to be continuously adjusted from low to high. we further show that our exprgan can be applied for other tasks, such as expression transfer, image retrieval, and data augmentation for training improved face expression recognition models. to tackle the small size of the training database, an effective incremental learning scheme is proposed. quantitative and qualitative evaluations on the widely used oulu - casia dataset demonstrate the effectiveness of exprgan. | arxiv:1709.03842 |
esa / nasa ' s solar orbiter ( so ) allows us to study the solar corona at closer distances and from different perspectives, which helps us to gain significant insights into the origins of the solar wind. in this work, we present the analysis of solar wind outflows from two locations : a narrow open - field corridor and a small, mid - latitude coronal hole. these outflows were observed off - limb by the metis coronagraph onboard so and on - disk by the extreme ultraviolet imaging spectrometer ( eis ) onboard hinode. magnetic field extrapolations suggest that the upflow regions seen in eis were the sources of the outflowing solar wind observed with metis. we find that the plasma associated with the narrow open - field corridor has higher electron densities and lower outflow velocities compared to the coronal hole plasma in the middle corona, even though the plasma properties of the two source regions in the low corona are found to be relatively similar. the speed of solar wind from the open - field corridor also shows no correlation with the magnetic field expansion factor, unlike the coronal hole. these pronounced differences at higher altitudes may arise from the dynamic nature of the low - middle corona, in which reconnection can readily occur and may play an important role in driving solar wind variability. | arxiv:2502.08290 |
of degree higher than 4. the 19th - century french mathematician evariste galois, extending prior work of paolo ruffini and joseph - louis lagrange, gave a criterion for the solvability of a particular polynomial equation in terms of the symmetry group of its roots ( solutions ). the elements of such a galois group correspond to certain permutations of the roots. at first, galois ' s ideas were rejected by his contemporaries, and published only posthumously. more general permutation groups were investigated in particular by augustin louis cauchy. arthur cayley ' s on the theory of groups, as depending on the symbolic equation θ n = 1 { \ displaystyle \ theta ^ { n } = 1 } ( 1854 ) gives the first abstract definition of a finite group. geometry was a second field in which groups were used systematically, especially symmetry groups as part of felix klein ' s 1872 erlangen program. after novel geometries such as hyperbolic and projective geometry had emerged, klein used group theory to organize them in a more coherent way. further advancing these ideas, sophus lie founded the study of lie groups in 1884. the third field contributing to group theory was number theory. certain abelian group structures had been used implicitly in carl friedrich gauss ' s number - theoretical work disquisitiones arithmeticae ( 1798 ), and more explicitly by leopold kronecker. in 1847, ernst kummer made early attempts to prove fermat ' s last theorem by developing groups describing factorization into prime numbers. the convergence of these various sources into a uniform theory of groups started with camille jordan ' s traite des substitutions et des equations algebriques ( 1870 ). walther von dyck ( 1882 ) introduced the idea of specifying a group by means of generators and relations, and was also the first to give an axiomatic definition of an " abstract group ", in the terminology of the time. as of the 20th century, groups gained wide recognition by the pioneering work of ferdinand georg frobenius and william burnside ( who worked on representation theory of finite groups ), richard brauer ' s modular representation theory and issai schur ' s papers. the theory of lie groups, and more generally locally compact groups was studied by hermann weyl, elie cartan and many others. its algebraic counterpart, the theory of algebraic groups, was first shaped by claude chevalley ( from the late 1930s ) and later by the work of armand borel | https://en.wikipedia.org/wiki/Group_(mathematics) |
the internet has become a critical communication infrastructure for citizens to organize protests and express dissatisfaction with their governments. this fact has not gone unnoticed, with governments clamping down on this medium via censorship, and circumvention researchers working to stay one step ahead. in this paper, we explore a promising new avenue for covert channels : real - time strategy - video games. video games have two key features that make them attractive cover protocols for censorship circumvention. first, due to the popularity of gaming platforms such as steam, there are a lot of different video games, each with their own protocols and server infrastructure. users of video - game - based censorship - circumvention tools can therefore diversify across many games, making it difficult for the censor to respond by simply blocking a single cover protocol. second, games in the same genre have many common features and concepts. as a result, the same covert channel framework can be easily adapted to work with many different games. this means that circumvention tool developers can stay ahead of the censor by creating a diverse set of tools and by quickly adapting to blockades created by the censor. we demonstrate the feasibility of this approach by implementing our coding scheme over two real - time strategy - games ( including a very popular closed - source game ). we evaluate the security of our system prototype - - castle - - by quantifying its resilience to a censor - adversary, its similarity to real game traffic, and its ability to avoid common pitfalls in covert channel design. we use our prototype to demonstrate that our approach can provide throughput which is amenable to transfer of textual data, such at e - mail, sms messages, and tweets, which are commonly used to organize political actions. | arxiv:1503.05904 |
in [ van beeumen, et. al, hpc asia 2020, https : / / www. doi. org / 10. 1145 / 3368474. 3368497 ] a scalable and matrix - free eigensolver was proposed for studying the many - body localization ( mbl ) transition of two - level quantum spin chain models with nearest - neighbor $ xx + yy $ interactions plus $ z $ terms. this type of problem is computationally challenging because the vector space dimension grows exponentially with the physical system size, and averaging over different configurations of the random disorder is needed to obtain relevant statistical behavior. for each eigenvalue problem, eigenvalues from different regions of the spectrum and their corresponding eigenvectors need to be computed. traditionally, the interior eigenstates for a single eigenvalue problem are computed via the shift - and - invert lanczos algorithm. due to the extremely high memory footprint of the lu factorizations, this technique is not well suited for large number of spins $ l $, e. g., one needs thousands of compute nodes on modern high performance computing infrastructures to go beyond $ l = 24 $. the matrix - free approach does not suffer from this memory bottleneck, however, its scalability is limited by a computation and communication imbalance. we present a few strategies to reduce this imbalance and to significantly enhance the scalability of the matrix - free eigensolver. to optimize the communication performance, we leverage the consistent space runtime, cspacer, and show its efficiency in accelerating the mbl irregular communication patterns at scale compared to optimized mpi non - blocking two - sided and one - sided rma implementation variants. the efficiency and effectiveness of the proposed algorithm is demonstrated by computing eigenstates on a massively parallel many - core high performance computer. | arxiv:2012.00217 |
personalized text - to - image ( t2i ) models not only produce lifelike and varied visuals but also allow users to tailor the images to fit their personal taste. these personalization techniques can grasp the essence of a concept through a collection of images, or adjust a pre - trained text - to - image model with a specific image input for subject - driven or attribute - aware guidance. yet, accurately capturing the distinct visual attributes of an individual image poses a challenge for these methods. to address this issue, we introduce ostaf, a novel parameter - efficient one - shot fine - tuning method which only utilizes one reference image for t2i personalization. a novel hypernetwork - powered attribute - focused fine - tuning mechanism is employed to achieve the precise learning of various attribute features ( e. g., appearance, shape or drawing style ) from the reference image. comparing to existing image customization methods, our method shows significant superiority in attribute identification and application, as well as achieves a good balance between efficiency and output quality. | arxiv:2403.11053 |
we have obtained deep j & ks - band images centered on a bright radio quiet qso um402 ( z _ { em } = 2. 856 ) using ircs camera and ao systems on subaru telescope, as well as retrieved wfc3 / f140w archive images. a faint galaxy ( m _ { k } = 23. 32 + / - 0. 05 in the vega system ) that lies ~ 2. 4 " north of the qso sightline has been clearly resolved in all three deep high resolution datasets, and appears as an irregular galaxy with two close components in the ks - band images ( separation ~ 0. 3 " ). given the small impact parameter ( b = 19. 6 kpc, at z _ { lls } = 2. 531 ), as well as the red color of ( j - ks ) _ { vega } ~ 1. 6, it might be a candidate galaxy giving rise to the lyman limit system absorption at z _ { abs } = 2. 531 seen in the qso spectrum. after carefully subtracting the psf from the qso images, the host galaxy of this bright radio quiet qso at z ~ 3 was marginally revealled. we placed a low limit of the host component of m _ { k } ~ 23. 3 according to our analyses. | arxiv:1301.1129 |
widely used software systems such as video encoders are by necessity highly configurable, with hundreds or even thousands of options to choose from. their users often have a hard time finding suitable values for these options ( i. e. finding a proper configuration of the software system ) to meet their goals for the tasks at hand, e. g. compress a video down to a certain size. one dimension of the problem is of course that performance depends on the input data : a video as input to an encoder like x264 or a file system fed to a tool like xz. to achieve good performance, users should therefore take into account both dimensions of ( 1 ) software variability and ( 2 ) input data. in this problem - statement paper, we conduct a large study over 8 configurable systems that quantifies the existing interactions between input data and configurations of software systems. the results exhibit that ( 1 ) inputs fed to software systems interact with their configuration options in non monotonous ways, significantly impacting their performance properties ( 2 ) tuning a software system for its input data makes it possible to multiply its performance by up to ten ( 3 ) input variability can jeopardize the relevance of performance predictive models for a field deployment. | arxiv:2112.07279 |
saturn ' s moon titan possesses stratospheric zonal winds that places it among a sparse class of planetary bodies known to have superrotation in their atmospheres. few measurements have been made of these speeds in the upper stratosphere, leaving their seasonal variations still not well understood. we examined observations made with the extended submillimeter array ( esma ) in 2009 march ( l \ textsubscript { s } = 355 \ textdegree { } ) and 2010 february ( l \ textsubscript { s } = 5 \ textdegree { } ), shortly before and after titan ' s northern spring equinox. cassini observations and atmospheric models find equinoctial periods to be especially dynamic. zonal wind calculations, derived from the doppler frequency shift of ch \ textsubscript { 3 } cn near 349. 4 ghz, yielded speeds of 128 $ \ pm $ 27 m s \ textsuperscript { - 1 } in 2009 and 209 $ \ pm $ 48 m s \ textsuperscript { - 1 } in 2010. we estimated the measured emission to originate from vertical altitudes of $ 336 ^ { + 112 } _ { - 88 } $ kilometers, equivalent to pressures of $ 3. 8 ^ { + 19. 2 } _ { - 3. 4 } $ pa, commensurate with titan ' s upper stratosphere / lower mesosphere. this suggests a possible increase in zonal speeds during this period. the results are then compared to those from previous cassini - inferred and direct - interferometric observations of winds, as well as general circulation model simulations, to form a more complete picture of the seasonal cycle of stratospheric zonal winds. | arxiv:2404.08832 |
threat, and provide information on understanding best methods and weapons to use in deterring or defeating it. = = = military logistics = = = the art and science of planning and carrying out the movement and maintenance of military forces. in its most comprehensive sense, it is those aspects or military operations that deal with the design, development, acquisition, storage, distribution, maintenance, evacuation, and disposition of material ; the movement, evacuation, and hospitalization of personnel ; the acquisition or construction, maintenance, operation, and disposition of facilities ; and the acquisition or furnishing of services. = = = military technology and equipment = = = military technology is not just the study of various technologies and applicable physical sciences used to increase military power. it may also extend to the study of production methods of military equipment, and ways to improve performance and reduce material and / or technological requirements for its production. an example is the effort expended by nazi germany to produce artificial rubbers and fuels to reduce or eliminate their dependence on imported pol ( petroleum, oil, and lubricants ) and rubber supplies. military technology is unique only in its application, not in its use of basic scientific and technological achievements. because of the uniqueness of use, military technological studies strive to incorporate evolutionary, as well as the rare revolutionary technologies, into their proper place of military application. = = military and society = = this speciality examines the ways that military and society interact and shape each other. the dynamic intersection where military and society meet is influenced by trends in society and the security environment. this field of study can be linked to works by clausewitz ( " war is the continuation of politics by other means " ) and sun tzu ( " if not in the interest of the state, do not act " ). the contemporary multi and interdisciplinary field traces its origin to world war ii and works by sociologists and political scientists. this field of study includes " all aspects of relations between armed forces, as a political, social and economic institution, and the society, state or political ethnic movement of which they are a part ". topics often included within the purview of military and society include : veterans, women in the military, military families, enlistment and retention, reserve forces, military and religion, military privatization, civil - military relations, civil - military cooperation, military and popular culture, military and the media, military and disaster assistance, military and the environment and the blurring of military and police functions. = = = recruitment and retention = = = in an all - | https://en.wikipedia.org/wiki/Military_science |
we use the lightcone $ ads _ { 3 } \ times s ^ { 3 } \ times t ^ { 4 } $ superstring sigma model with fermions and bosons subject to twisted boundary conditions to find the ground state energy in the semi - classical approximation where effective string tension $ h $ and the light - cone momentum $ l $ are sent to infinity in such a way that $ { \ cal j } \ equiv l / h $ is kept fixed. we then analyse the ground state energy of the model by means of the mirror tba equations for the $ ads _ { 3 } \ times s ^ { 3 } \ times t ^ { 4 } $ superstring in the pure rr background. the calculation is performed for small twist $ \ mu $ with $ l $ and $ h $ fixed, for large $ l $ with $ \ mu $ and $ h $ fixed, and for small $ h $ with $ \ mu $ and $ l $ fixed. in these limits the contribution of the gapless worldsheet modes coming from the $ t ^ 4 $ bosons and fermions can be computed exactly, and is shown to be proportional to $ hl / ( 4l ^ 2 - 1 ) $. comparison with the semi - classical result shows that the tba equations involve only one $ y _ 0 $ - function for massless excitations but not two as was conjectured before. some of the results obtained are generalised to the mixed - flux $ ads _ { 3 } \ times s ^ { 3 } \ times t ^ { 4 } $ superstring. | arxiv:2305.17128 |
we propose an efficient scheme for simulating the topological phases of matter based on silicon - vacancy ( siv ) center arrays in phononic crystals. this phononic band gap structure allows for long - range spin - spin interactions with a tunable profile. under a particular periodic microwave driving, the band - gap mediated spin - spin interaction can be further designed with the form of the su - schrieffer - heeger ( ssh ) hamiltonian. in momentum space, we investigate the topological characters of the ssh model, and show that the topological nontrivial phase can be obtained through modulating the periodic driving fields. furthermore, we explore the zero - energy topological edge states at the boundary of the color center arrays, and study the robust quantum information transfer via the topological edge states. this setup provides a scalable and promising platform for studying topological quantum physics and quantum information processing with color centers and phononic crystals. | arxiv:2001.01397 |
foreground components in the cosmic microwave background ( cmb ) are sparse in a needlet representation, due to their specific morphological features ( anisotropy, non - gaussianity ). this leads to the possibility of applying needlet thresholding procedures as a component separation tool. in this work, we develop algorithms based on different needlet - thresholding schemes and use them as extensions of existing, well - known component separation techniques, namely ilc and template - fitting. we test soft - and hard - thresholding schemes, using different procedures to set the optimal threshold level. we find that thresholding can be useful as a denoising tool for internal templates in experiments with few frequency channels, in conditions of low signal - to - noise. we also compare our method with other denoising techniques, showing that thresholding achieves the best performance in terms of reconstruction accuracy and data compression while preserving the map resolution. the best results in our tests are in particular obtained when considering template - fitting in an lspe like experiment, especially for b - mode spectra. | arxiv:1911.01298 |
we study ergodic averages for a class of pseudodifferential operators on the flat n - dimensional torus with respect to the schr \ " odinger evolution. the later can be consider a quantization of the geodesic flow on $ \ bt ^ n $. we prove that, up to semi - classically negligible corrections, such ergodic averages are translationally invariant operators. | arxiv:math-ph/0312053 |
quorum sensing is the mechanism by which bacteria communicate and synchronize group behaviors. quantitative information on parameters such as the copy number of particular quorum - sensing proteins should contribute strongly to understanding how the quorum - sensing network functions. here we show that the copy number of the master regulator protein luxr in vibrio harveyi, can be determined in vivo by exploiting small - number fluctuations of the protein distribution when cells undergo division. when a cell divides, both its volume and luxr protein copy number n are partitioned with slight asymmetries. we have measured the distribution functions describing the partitioning of the protein fluorescence and the cell volume. the fluorescence distribution is found to narrow systematically as the luxr population increases while the volume partitioning is unchanged. analyzing these changes statistically, we have determined that n = 80 - 135 dimers at low cell density and 575 dimers at high cell density. in addition, we have measured the static distribution of luxr over a large ( 3, 000 ) clonal population. combining the static and time - lapse experiments, we determine the magnitude of the fano factor of the distribution. this technique has broad applicability as a general, in vivo technique for measuring protein copy number and burst size. | arxiv:1001.0977 |
community detection is one of the most important methodological fields of network science, and one which has attracted a significant amount of attention over the past decades. this area deals with the automated division of a network into fundamental building blocks, with the objective of providing a summary of its large - scale structure. despite its importance and widespread adoption, there is a noticeable gap between what is arguably the state - of - the - art and the methods that are actually used in practice in a variety of fields. here we attempt to address this discrepancy by dividing existing methods according to whether they have a " descriptive " or an " inferential " goal. while descriptive methods find patterns in networks based on context - dependent notions of community structure, inferential methods articulate generative models, and attempt to fit them to data. in this way, they are able to provide insights into the mechanisms of network formation, and separate structure from randomness in a manner supported by statistical evidence. we review how employing descriptive methods with inferential aims is riddled with pitfalls and misleading answers, and thus should be in general avoided. we argue that inferential methods are more typically aligned with clearer scientific questions, yield more robust results, and should be in many cases preferred. we attempt to dispel some myths and half - truths often believed when community detection is employed in practice, in an effort to improve both the use of such methods as well as the interpretation of their results. | arxiv:2112.00183 |
surface fermi arcs ( sfas ), the unique open fermi - surfaces ( fss ) discovered recently in topological weyl semimetals ( twss ), are unlike closed fss in conventional materials and can give rise to many exotic phenomena, such as anomalous sfa - mediated quantum oscillations, chiral magnetic effects, three - dimensional quantum hall effect, non - local voltage generation and anomalous electromagnetic wave transmission. here, by using in - situ surface decoration, we demonstrate successful manipulation of the shape, size and even the connections of sfas in a model tws, nbas, and observe their evolution that leads to an unusual topological lifshitz transition not caused by the change of the carrier concentration. the phase transition teleports the sfas between different parts of the surface brillouin zone. despite the dramatic surface evolution, the existence of sfas is robust and each sfa remains tied to a pair of weyl points of opposite chirality, as dictated by the bulk topology. | arxiv:1908.01155 |
particle accelerators are time - varying systems whose components are perturbed by external disturbances. tuning accelerators can be a time - consuming process involving manual adjustment of multiple components, such as rf cavities, to minimize beam loss due to time - varying drifts. the high dimensionality of the system ( $ \ sim $ 100 amplitude and phase rf settings in the lansce accelerator ) makes it difficult to achieve optimal operation. the time - varying drifts and the dimensionality make system parameter estimation a challenging optimization problem. in this work, we propose a variational autoencoded latent regression ( valer ) model for robust estimation of system parameters using 2d unique projections of a charged particle beam ' s 6d phase space. in valer, vae projects the phase space projections into a lower - dimensional latent space, and a dense neural network maps the latent space onto the space of system parameters. the trained network can predict system parameters for unseen phase space projections. furthermore, valer can generate new projections by randomly sampling the latent space of vae and also estimate the corresponding system parameters. | arxiv:2406.01532 |
on a smooth, non - compact, complete, boundaryless, connected riemannian manifold $ ( m, g ) $, there are three kinds of objects that have been studied extensively : $ \ bullet $ viscosity solutions to the hamilton - jacobi equation determined by the riemannian metric ; $ \ bullet $ ends introduced by freudenthal and more general other remainders from compactification theory ; $ \ bullet $ various kinds of ideal boundaries introduced by gromov. in this paper, we will present some initial relationship among these three kinds of objects and some related topics are also considered. | arxiv:1312.6271 |
in the era of cloud computing and data - driven applications, it is crucial to protect sensitive information to maintain data privacy, ensuring truly reliable systems. as a result, preserving privacy in deep learning systems has become a critical concern. existing methods for privacy preservation rely on image encryption or perceptual transformation approaches. however, they often suffer from reduced task performance and high computational costs. to address these challenges, we propose a novel privacy - preserving framework that uses a set of deformable operators for secure task learning. our method involves shuffling pixels during the analog - to - digital conversion process to generate visually protected data. those are then fed into a well - known network enhanced with deformable operators. using our approach, users can achieve equivalent performance to original images without additional training using a secret key. moreover, our method enables access control against unauthorized users. experimental results demonstrate the efficacy of our approach, showcasing its potential in cloud - based scenarios and privacy - sensitive applications. | arxiv:2404.05828 |
the kustin - miller complex construction, due to a. kustin and m. miller, can be applied to a pair of resolutions of gorenstein rings with certain properties to obtain a new gorenstein ring and a resolution of it. it gives a tool to construct and analyze gorenstein rings of high codimension. we describe the kustin - miller complex and its implementation in the macaulay2 package kustinmiller, and explain how it can be applied to explicit examples. | arxiv:1103.2314 |
the effect of non - magnetic zn impurity on superconductivity in lafe $ _ { 1 - y } $ zn $ _ y $ aso $ _ { 1 - x } $ f $ _ x $ system is studied systematically. in the presence of zn impurity, the superconducting transition temperature increases in the under - doped regime, remains unchanged in the optimally doped regime, and is severely suppressed in the over - doped regime. our results suggest a switch of the symmetry of the superconducting order parameters from a $ s $ - wave to $ s _ { \ pm } $ or $ d $ - wave states as the charge carrier doping increases in feas - based superconductors. | arxiv:1001.4317 |
a pump source is one of the essential prerequisites in order to achieve lasing, and, in most cases, a stronger pump leads to higher laser power at the output. however, this behavior may be suppressed if two pump beams are used. in this work, it is shown that lasing around the 1600 nm band can be suppressed completely if two pumps, at wavelengths of 980 nm and 1550 nm, are applied simultaneously to a yb : er - doped microlaser, whereas it can be revived by switching one of them off. this phenomenon can be explained by assuming that the existence of one pump ( 980 nm ) changes the role of the other pump ( 1550 nm ) ; more specifically, the 1550 nm pump starts to consume the population inversion instead of increasing it when the 980 nm pump power exceeds a certain value. as a result, the two pump fields lead to a closed - loop transition within the gain medium ( i. e., erbium ions ). this study unveils an interplay similar with coherence effects between different pump pathways, which provides a reference for designing the laser pump and may have applications in lasing control. | arxiv:1706.02855 |
environment maps are used to simulate reflections off curved objects. we present a technique to reflect a user, or a group of users, in a real environment, onto a virtual object, in a virtual reality application, using the live video feeds from a set of cameras, in real - time. our setup can be used in a variety of environments ranging from outdoor or indoor scenes. | arxiv:cs/0304011 |
we consider continuous extensions of minimal rotations on a locally connected compact group x by arbitrary locally compact lie groups and prove regularity ( i. e. the existence of orbit closures which project onto the whole basis x ) in certain special situations beyond the already known nilpotent case. we further discuss an open question on cocycles acting on homogeneous spaces which seems to be the missing key for a general regularity theorem. | arxiv:0802.4369 |
we define a version of spectral invariant in the vortex floer theory for a $ g $ - hamiltonian manifold $ m $. this defines potentially new ( partial ) symplectic quasi - morphism and quasi - states when $ m / / g $ is not semi - positive. we also establish a relation between vortex hamiltonian floer homology and woodward ' s quasimap floer homology by constructing a closed - open string map between them. this yields applications to study non - displaceability problems of subsets in $ m / / g $ | arxiv:1506.03349 |
the structure of three - jet e + e - - > b bbar g events has been studied using hadronic z0 decays recorded in the sld experiment at slac. three - jet final states were selected and the ccd - based vertex detector was used to identify two of the jets as b or bbar ; the remaining jet in each event was tagged as the gluon jet. distributions of the gluon energy and polar angle with respect to the electron beam were measured over the full kinematic range, and used to test the predictions of perturbative qcd. we find that beyond - leading - order qcd calculations are needed to reproduce the features seen in the data. the energy distribution is sensitive to an anomalous b chromomagnetic moment kappa at the b bbar g vertex. we measured kappa to be consistent with zero and set 95 % c. l. limits on its value, - 0. 06 < kappa < 0. 04. | arxiv:hep-ex/0205066 |
feltor is a modular and free scientific software package. it allows developing platform independent code that runs on a variety of parallel computer architectures ranging from laptop cpus to multi - gpu distributed memory systems. feltor consists of both a numerical library and a collection of application codes built on top of the library. its main target are two - and three - dimensional drift - and gyro - fluid simulations with discontinuous galerkin methods as the main numerical discretization technique. we observe that numerical simulations of a recently developed gyro - fluid model produce non - deterministic results in parallel computations. first, we show how we restore accuracy and bitwise reproducibility algorithmically and programmatically. in particular, we adopt an implementation of the exactly rounded dot product based on long accumulators, which avoids accuracy losses especially in parallel applications. however, reproducibility and accuracy alone fail to indicate correct simulation behaviour. in fact, in the physical model slightly different initial conditions lead to vastly different end states. this behaviour translates to its numerical representation. pointwise convergence, even in principle, becomes impossible for long simulation times. in a second part, we explore important performance tuning considerations. we identify latency and memory bandwidth as the main performance indicators of our routines. based on these, we propose a parallel performance model that predicts the execution time of algorithms implemented in feltor and test our model on a selection of parallel hardware architectures. we are able to predict the execution time with a relative error of less than 25 % for problem sizes between 0. 1 and 1000 mb. finally, we find that the product of latency and bandwidth gives a minimum array size per compute node to achieve a scaling efficiency above 50 % ( both strong and weak ). | arxiv:1807.01971 |
we introduce a mathematically rigorous framework based on rough path theory to model stochastic spiking neural networks ( ssnns ) as stochastic differential equations with event discontinuities ( event sdes ) and driven by c \ ` adl \ ` ag rough paths. our formalism is general enough to allow for potential jumps to be present both in the solution trajectories as well as in the driving noise. we then identify a set of sufficient conditions ensuring the existence of pathwise gradients of solution trajectories and event times with respect to the network ' s parameters and show how these gradients satisfy a recursive relation. furthermore, we introduce a general - purpose loss function defined by means of a new class of signature kernels indexed on c \ ` adl \ ` ag rough paths and use it to train ssnns as generative models. we provide an end - to - end autodifferentiable solver for event sdes and make its implementation available as part of the $ \ texttt { diffrax } $ library. our framework is, to our knowledge, the first enabling gradient - based training of ssnns with noise affecting both the spike timing and the network ' s dynamics. | arxiv:2405.13587 |
current mobile manipulators and high - fidelity simulators lack the ability to seamlessly operate and simulate across integrated environments spanning sea, air, and land. to address this gap, we introduce aerial - aquatic manipulators ( aams ) in sea, air, and land simulator ( seals ), a comprehensive and photorealistic simulator designed for aams to operate and learn in these diverse environments. the development of aam - seals tackles several significant challenges, including the creation of integrated controllers for flying, swimming, and manipulation, and the high - fidelity simulation of aerial dynamics and hydrodynamics leveraging particle - based hydrodynamics. our evaluation demonstrates smooth operation and photorealistic transitions across air, water, and their interfaces. we quantitatively validate the fidelity of particle - based hydrodynamics by comparing position - tracking errors across real - world and simulated systems. aam - seals benefits a broad range of robotics communities, including robot learning, aerial robotics, underwater robotics, mobile manipulation, and robotic simulators. we will open - source our code and data to foster the advancement of research in these fields. the overview video is available at https : / / youtu. be / mbqiiryvr78. visit our project website at https : / / aam - seals. umd. edu for more details. | arxiv:2412.19744 |
we improve upon the lower bound for 3 - colour hypergraph ramsey numbers, showing, in the 3 - uniform case, that \ [ r _ 3 ( l, l, l ) \ geq 2 ^ { l ^ { c \ log \ log l } }. \ ] the old bound, due to erd \ h { o } s and hajnal, was \ [ r _ 3 ( l, l, l ) \ geq 2 ^ { c l ^ 2 \ log ^ 2 l }. \ ] | arxiv:0711.5004 |
in particle physics, most of the classical models consider that the centre of mass and centre of charge of an elementary particle, are the same point. this presumes some particular relationship between the charge and mass distribution, a feature which cannot be checked experimentally. in this paper we give three different kinds of arguments suggesting that, if assumed different points, the centre of charge of an elementary spinning particle moves in a helical motion at the speed of light, and it thus satisfies, in general, a fourth order differential equation. if assumed a kind of rigid body structure, it is sufficient the description of the centre of charge to describe also the evolution of the centre of mass and the rotation of the body. this assumption of a separation betwen the centre of mass and centre of charge gives a contribution to the spin of the system and also justifies the existence of a magnetic moment produced by the relative motion of the centre of charge. this corresponds to an improved model of a charged elementary particle, than the point particle case. this means that a lagrangian formalism for describing elementary spinning particles has to depend, at least, up to the acceleration of the position of the charge, to properly obtain fourth order dynamical equations. this result is compared with the description of a classical dirac particle obtained from a general lagrangian formalism for describing spinning particles. | arxiv:0807.2512 |
ieee global history network, which now redirects to engineering and technology history wiki. = = = ieee foundation = = = the ieee foundation is a charitable foundation established in 1973 to support and promote technology education, innovation, and excellence. it is incorporated separately from the ieee, although it has a close relationship to it. members of the board of directors of the foundation are required to be active members of ieee, and one third of them must be current or former members of the ieee board of directors. initially, the role of the ieee foundation was to accept and administer donations for the ieee awards program, but donations increased beyond what was necessary for this purpose, and the scope was broadened. in addition to soliciting and administering unrestricted funds, the foundation also administers donor - designated funds supporting particular educational, humanitarian, historical preservation, and peer recognition programs of the ieee. as of the end of 2014, the foundation ' s total assets were nearly $ 45 million, split equally between unrestricted and donor - designated funds. = = controversies = = = = = huawei ban = = = in may 2019, ieee restricted huawei employees from peer reviewing papers or handling papers as editors due to the " severe legal implications " of u. s. government sanctions against huawei. as members of its standard - setting body, huawei employees could continue to exercise their voting rights, attend standards development meetings, submit proposals and comment in public discussions on new standards. the ban sparked outrage among chinese scientists on social media. some professors in china decided to cancel their memberships. on june 3, 2019, ieee lifted restrictions on huawei ' s editorial and peer review activities after receiving clearance from the united states government. = = = position on the russian invasion of ukraine = = = on february 26, 2022, the chair of the ieee ukraine section, ievgen pichkalov, publicly appealed to the ieee members to " freeze [ ieee ] activities and membership in russia " and requested " public reaction and strict disapproval of russia ' s aggression " from the ieee and ieee region 8. on march 17, 2022, an article in the form of q & a interview with ieee russia ( siberia ) senior member roman gorbunov titled " a russian perspective on the war in ukraine " was published in ieee spectrum to demonstrate " the plurality of views among ieee members " and the " views that are at odds with international reporting on the war in ukraine ". on march 30, 2022, activist anna rohrbach created an open letter to | https://en.wikipedia.org/wiki/Institute_of_Electrical_and_Electronics_Engineers |
this paper proposes a novel module called middle spectrum grouped convolution ( msgc ) for efficient deep convolutional neural networks ( dcnns ) with the mechanism of grouped convolution. it explores the broad " middle spectrum " area between channel pruning and conventional grouped convolution. compared with channel pruning, msgc can retain most of the information from the input feature maps due to the group mechanism ; compared with grouped convolution, msgc benefits from the learnability, the core of channel pruning, for constructing its group topology, leading to better channel division. the middle spectrum area is unfolded along four dimensions : group - wise, layer - wise, sample - wise, and attention - wise, making it possible to reveal more powerful and interpretable structures. as a result, the proposed module acts as a booster that can reduce the computational cost of the host backbones for general image recognition with even improved predictive accuracy. for example, in the experiments on imagenet dataset for image classification, msgc can reduce the multiply - accumulates ( macs ) of resnet - 18 and resnet - 50 by half but still increase the top - 1 accuracy by more than 1 %. with 35 % reduction of macs, msgc can also increase the top - 1 accuracy of the mobilenetv2 backbone. results on ms coco dataset for object detection show similar observations. our code and trained models are available at https : / / github. com / hellozhuo / msgc. | arxiv:2304.06305 |
given a sequence of polynomials $ ( p _ n ) _ { n \ in \ mathbb { n } } $ with only nonpositive zeros, the aim of this article is to present a user - friendly approach for determining the limiting zero distribution of $ p _ n $ as $ \ mathrm { deg } \, p _ n \ to \ infty $. the method is based on establishing an equivalence between the existence of a limiting empirical zero distribution $ \ mu $ and the existence of an exponential profile $ g $ associated with the coefficients of the polynomials $ ( p _ n ) _ { n \ in \ mathbb { n } } $. the exponential profile $ g $, which can be roughly described by $ [ z ^ k ] p _ n ( z ) \ approx \ exp ( n g ( k / n ) ) $, offers a direct route to computing the cauchy transform $ g $ of $ \ mu $ : the functions $ t \ mapsto tg ( t ) $ and $ \ alpha \ mapsto \ exp ( - g ' ( \ alpha ) ) $ are mutual inverses. this relationship, in various forms, has previously appeared in the literature, most notably in the paper [ van assche, fano and ortolani, siam j. math. anal., 1987 ]. as a first contribution, we present a self - contained probabilistic proof of this equivalence by representing the polynomials as generating functions of sums of independent bernoulli random variables. this probabilistic framework naturally lends itself to tools from large deviation theory, such as the exponential change of measure. the resulting theorems generalize and unify a range of previously known results, which were traditionally established through analytic or combinatorial methods. secondly, using the profile - based approach, we investigate how the exponential profile and the limiting zero distribution behave under certain operations on polynomials, including finite free convolutions, hadamard products, and repeated differentiation. in particular, our approach yields new proofs of the convergence results ` $ \ boxplus _ n \ to \ boxplus $ ' and ` $ \ boxtimes _ n \ to \ boxtimes $ ', extending them to cases where the distributions are not necessarily compactly supported. | arxiv:2504.11593 |
in this paper we revisit a result due to franz rellich on smoothness of solutions of parametrized linear systems. with this result as a starting point, we obtain finer smoothness results in an elementary fashion and propose an efficient adjoint algorithm for computing sensitivities of $ ( n - 1 ) $ - deficient systems, being $ n $ the order of the system. | arxiv:2301.13164 |
with the use of mathematical techniques of tropical geometry, it was shown by mikhalkin some twenty years ago that certain gromov - witten invariants associated with topological quantum field theories of pseudoholomorphic maps can be computed by going to the tropical limit of the geometries in question. here we examine this phenomenon from the physics perspective of topological quantum field theory in the path integral representation, beginning with the case of the topological sigma model before coupling it to topological gravity. we identify the tropicalization of the localization equations, investigate its geometry and symmetries, and study the theory and its observables using the standard cohomological brst methods. we find that the worldsheet theory exhibits a nonrelativistic structure, similar to theories of the lifshitz type. its path - integral formulation does not require a worldsheet complex structure ; instead, it is based on a worldsheet foliation structure. | arxiv:2311.00745 |
queer students often encounter discrimination and a lack of belonging in their academic environments. this may be especially true in heteronormative male - dominated fields like software engineering, which already faces a diversity crisis. in contrast, disciplines like humanities have a higher proportion of queer students, suggesting a more diverse academic culture. while prior research has explored queer students ' challenges in stem fields, limited attention has been given to how experiences differ between the sociotechnical, yet highly heteronormative, field of software engineering and the socioculturally inclusive humanities. this study addresses that gap by comparing 165 queer software engineering and 119 queer humanities students experiences. our findings reveal that queer students in software engineering are less likely to be open about their sexuality, report a significantly lower sense of belonging, and encounter more academic challenges compared to their peers in the humanities. despite these challenges, queer software engineering students show greater determination to continue their studies. these insights suggest that software engineering could enhance inclusivity by adopting practices commonly seen in the humanities, such as integrating inclusive policies in classrooms, to create a more welcoming environment where queer students can thrive. | arxiv:2503.04576 |
in the setting of secure multiparty computation ( mpc ), a set of mutually distrusting parties wish to jointly compute a function, while guaranteeing the privacy of their inputs and the correctness of the output. an mpc protocol is called \ emph { fully secure } if no adversary can prevent the honest parties from obtaining their outputs. a protocol is called \ emph { fair } if an adversary can prematurely abort the computation, however, only before learning any new information. we present highly efficient transformations from fair computations to fully secure computations, assuming the fraction of honest parties is constant ( e. g., $ 1 \ % $ of the parties are honest ). compared to previous transformations that require linear invocations ( in the number of parties ) of the fair computation, our transformations require super - logarithmic, and sometimes even super - constant, such invocations. the main idea is to delegate the computation to chosen random committees that invoke the fair computation. apart from the benefit of uplifting security, the reduction in the number of parties is also useful, since only committee members are required to work, whereas the remaining parties simply " listen " to the computation over a broadcast channel. | arxiv:2105.00962 |
the contact binary kuiper belt object ( 486958 ) arrokoth, targeted by new horizons mission, has a unique slope pattern, which is a result of its irregular bilobate surface shape and high spin period. thus, some peculiar topographic regions on its surface are predisposed to lose or accumulate material, as a long circular depression feature, an impact crater called maryland, on its small lobe. the equilibrium points of arrokoth are also directly related to the structure of the environment near these surface features. in this work, we performed numerical simulations around arrokoth to explore the fate of particles close to equilibrium points and their dynamical connection with its surface features. our results suggest that most of these particles in a ring inside the arrokoth ' s rotational roche lobe fall near the equatorial region of the maryland impact crater or close to the bright spots area on the large lobe. also, particles in a spherical cloud orbiting arrokoth accumulate preferentially near low - mid - latitudes regions close to the longitudes of maryland crater and bright spots area. in contrast, a few particles will fall in regions diametrically opposite to them, as in the ll _ term boundary on the large lobe. high - latitudes are those more empty of impacts, as in polar sites. in addition, particles larger than a couple of microns are not significantly perturbed by solar radiation pressure in the environment around arrokoth. | arxiv:2203.14444 |
new measurement of sub - threshold $ k ^ * ( 892 ) ^ 0 $ and $ k ^ 0 $ production is presented. the experimental data complete the measurement of strange particles produced in al + al collisions at 1. 9 $ a $ gev measured with the fopi detector at sis / gsi. the $ k ^ * ( 892 ) ^ 0 $ / $ k ^ 0 $ yield ratio is found to be $ 0. 0315 \ pm 0. 006 ( \ mathrm { stat. } ) \ pm 0. 012 ( \ mathrm { syst. } ) $ and is in good agreement with the urqmd model prediction. these measurements provide information on in - medium cross section of $ k ^ + $ - $ \ pi ^ - $ fusion which is the dominant process on sub - threshold $ k ^ * ( 892 ) ^ 0 $ production. | arxiv:1006.1905 |
dual - function radar communication ( dfrc ) systems incorporate both radar and communication functions by sharing spectrum, hardware and rf signal processing chains. future technologies, such as 6g, are envisioned to support multiple communication platforms along with radar sensing, thus leading to high dynamism and competition for the available resources. in such settings, whenever communication takes precedence, a likely scenario is dynamically changing rf chain and antenna availability for sensing. this necessitates real - time beam redesign to cover the field - of - view ( fov ), solving which is intractable via computationally expensive optimization approaches. we propose that classic windowing techniques are still relevant and much more practical than optimization methods in such dynamic scenarios. specifically, parametrized windows can be used in a strategic way to adapt to varying resource availability while sustaining sensing performance. | arxiv:2412.16661 |
the literature on dedekind sums is vast. in this expository paper we show that there is a common thread to many generalizations of dedekind sums, namely through the study of lattice point enumeration of rational polytopes. in particular, there are some natural finite fourier series which we call fourier - dedekind sums, and which form the building blocks of the number of partitions of an integer from a finite set of positive integers. this problem also goes by the name of the ` coin exchange problem '. dedekind sums have enjoyed a resurgence of interest recently, from such diverse fields as topology, number theory, and combinatorial geometry. the fourier - dedekind sums we study here include as special cases generalized dedekind sums studied by berndt, carlitz, grosswald, knuth, rademacher, and zagier. our interest in these sums stems from the appearance of dedekind ' s and zagier ' s sums in lattice point count formulas for polytopes. using some simple generating functions, we show that generalized dedekind sums are natural ingredients for such formulas. as immediate ` geometric ' corollaries to our formulas, we obtain and generalize reciprocity laws of dedekind, zagier, and gessel. finally, we prove a polynomial - time complexity result for zagier ' s higher - dimensional dedekind sums. | arxiv:math/0112076 |
quandles can be regarded as generalizations of symmetric spaces. among symmetric spaces, two - point homogeneous riemannian manifolds would be the most fundamental ones. in this paper, we define two - point homogeneous quandles analogously, and classify those with prime cardinality. | arxiv:1312.6915 |
we provide conjectural necessary and ( separately ) sufficient conditions for the hilbert scheme of points of a given length to have the maximum dimension tangent space at a point. the sufficient condition is claimed for 3d and reduces the original problem to a problem in convex geometry. proving either of the two conjectural statements will in particular resolve a long - standing conjecture by brian \ c { c } on and iarrobino back in the ' 70s for the case of the powers of the maximal ideal. furthermore, for specific classes of lengths, we conjecturally classify points satisfying the conjectural sufficient conditions. this in particular ( conjecturally ) provides many new explicit families of examples of maximum dimension tangent space at a point of the hilbert schemes of points of lengths strictly between two consecutive tetrahedral numbers $ { 3 + k \ choose 3 } $. | arxiv:2312.04520 |
clustering problems are well - studied in a variety of fields such as data science, operations research, and computer science. such problems include variants of centre location problems, $ k $ - median, and $ k $ - means to name a few. in some cases, not all data points need to be clustered ; some may be discarded for various reasons. we study clustering problems with outliers. more specifically, we look at uncapacitated facility location ( ufl ), $ k $ - median, and $ k $ - means. in ufl with outliers, we have to open some centres, discard up to $ z $ points of $ \ cal x $ and assign every other point to the nearest open centre, minimizing the total assignment cost plus centre opening costs. in $ k $ - median and $ k $ - means, we have to open up to $ k $ centres but there are no opening costs. in $ k $ - means, the cost of assigning $ j $ to $ i $ is $ \ delta ^ 2 ( j, i ) $. we present several results. our main focus is on cases where $ \ delta $ is a doubling metric or is the shortest path metrics of graphs from a minor - closed family of graphs. for uniform - cost ufl with outliers on such metrics we show that a multiswap simple local search heuristic yields a ptas. with a bit more work, we extend this to bicriteria approximations for the $ k $ - median and $ k $ - means problems in the same metrics where, for any constant $ \ epsilon > 0 $, we can find a solution using $ ( 1 + \ epsilon ) k $ centres whose cost is at most a $ ( 1 + \ epsilon ) $ - factor of the optimum and uses at most $ z $ outliers. we also show that natural local search heuristics that do not violate the number of clusters and outliers for $ k $ - median ( or $ k $ - means ) will have unbounded gap even in euclidean metrics. furthermore, we show how our analysis can be extended to general metrics for $ k $ - means with outliers to obtain a $ ( 25 + \ epsilon, 1 + \ epsilon ) $ bicriteria. | arxiv:1707.04295 |
sample selection models represent a common methodology for correcting bias induced by data missing not at random. these models are not empirically identifiable without exclusion restrictions. in other words, some variables predictive of missingness do not affect the outcome model of interest. the drive to establish this requirement often leads to the inclusion of irrelevant variables in the model. a recent proposal uses adaptive lasso to circumvent this problem, but its performance depends on the so - called covariance assumption, which can be violated in small to moderate samples. additionally, there are no tools yet for post - selection inference for this model. to address these challenges, we propose two families of spike - and - slab priors to conduct bayesian variable selection in sample selection models. these prior structures allow for constructing a gibbs sampler with tractable conditionals, which is scalable to the dimensions of practical interest. we illustrate the performance of the proposed methodology through a simulation study and present a comparison against adaptive lasso and stepwise selection. we also provide two applications using publicly available real data. an implementation and code to reproduce the results in this paper can be found at https : / / github. com / adam - iqbal / selection - spike - slab. | arxiv:2312.03538 |
atomic shared objects, whose operations take place instantaneously, are a powerful abstraction for designing complex concurrent programs. since they are not always available, they are typically substituted with software implementations. a prominent condition relating these implementations to their atomic specifications is linearizability, which preserves safety properties of the programs using them. however linearizability does not preserve hyper - properties, which include probabilistic guarantees of randomized programs : an adversary can greatly amplify the probability of a bad outcome. this unwelcome behavior prevents modular reasoning, which is the key benefit provided by the use of linearizable object implementations. a more restrictive property, strong linearizability, does preserve hyper - properties but it is impossible to achieve in many situations. this paper suggests a novel approach to blunting the adversary ' s additional power that works even in cases where strong linearizability is not achievable. we show that a wide class of linearizable implementations, including well - known ones for registers and snapshots, can be modified to approximate the probabilistic guarantees of randomized programs when using atomic objects. the technical approach is to transform the algorithm of each method of an existing linearizable implementation by repeating a carefully chosen prefix of the method several times and then randomly choosing which repetition to use subsequently. we prove that the probability of a bad outcome decreases with the number of repetitions, approaching the probability attained when using atomic objects. the class of implementations to which our transformation applies includes the abd implementation of a shared register using message - passing and the afek et al. implementation of an atomic snapshot using single - writer registers. | arxiv:2106.15554 |
in this work, it is shown that electrostatic solitons in a plasma with turbulent heating of the electrons through an accelerating electric field can form with very high velocities, reaching up to several order of magnitudes larger than the equilibrium ion - sound speed. the possible parameter regime, where this work may be relevant, can be found in the so - called " dead zones " of a protoplanetary disk. though these zones are stable to magnetorotational instability, the resultant turbulence can in fact heat the electrons making them follow a highly non - maxwellian velocity distribution. we show that these fast - moving solitons can reach very high velocities. with electron velocity distribution described by the davydov distribution function, we argue that these solitons can be an effective mechanism for energy equilibration in such a situation through soliton decay and radiation. | arxiv:2308.06681 |
we consider the 4d compact u ( 1 ) gauge theory with extended action s = - beta sum _ p cos theta _ p - gamma sum _ p cos 2 theta _ p we give a full characterization of the phase diagram of this model using the notion of flux. the relation with the usual monopole picture is discussed. in analogy with the xy model we consider the helicity modulus \ cite { jose : 1977gm } for this theory, and show that it is an order parameter. analyzing the finite - size effects of the helicity modulus we conclude that the transition is first - order. the value of this order parameter is related to the renormalized coupling beta _ r. we measure beta ^ c _ r at the transition point and give a counterexample to its conjectured universal value \ cite { cardy : jg }. | arxiv:hep-lat/0311006 |
context. this is the second work dedicated to the observed parallelism between galaxy clusters and early - type galaxies. the focus is on the distribution of these systems in the scaling relations ( srs ) observed when effective radii, effective surface brightness, total luminosities and velocity dispersions are mutually correlated. aims. using the data of the illustris simulation we try to speculate on the origin of the observed srs. methods. we compare the observational srs extracted from the database of the wide - field nearby galaxy - cluster survey ( wings ) with the relevant parameters coming from the illustris simulations. then we use the simulated data at different redshift to infer the evolution of the srs. results. the comparison demonstrate that galaxy clusters ( gcs ) at z ~ 0 follow the same log ( l ) - log ( sigma ) relation of early - type galaxies ( etgs ) and that both in the log ( ie ) - log ( re ) and log ( re ) - log ( m * ) planes the distribution of gcs is along the sequence defined by the brightest and massive early - type galaxies ( bcgs ). the illustris simulation reproduces the tails of the massive galaxies visible both in the log ( ie ) - log ( re ) and log ( re ) - log ( m * ) planes, but fail to give the correct estimate of the effective radii of the dwarf galaxies that appear too large and those of gcs that are too small. the evolution of the srs up to z = 4 permits to reveal the complex evolutionary paths of galaxies in the srs and indicate that the line marking the zone of exclusion ( zoe ), visible both in the log ( ie ) - log ( re ) and log ( re ) - log ( m * ) planes, is the trend followed by virialized and passively evolving systems. conclusions. we speculate that the observed srs originate from the intersection of the virial theorem and a relation l = l _ 0 x sigma ^ beta where the luminosities depend on the star formation history. | arxiv:1907.09367 |
with the development of deep learning and artificial intelligence, audio synthesis has a pivotal role in the area of machine learning and shows strong applicability in the industry. meanwhile, significant efforts have been dedicated by researchers to handle multimodal tasks at present such as audio - visual multimodal processing. in this paper, we conduct a survey on audio synthesis and audio - visual multimodal processing, which helps understand current research and future trends. this review focuses on text to speech ( tts ), music generation and some tasks that combine visual and acoustic information. the corresponding technical methods are comprehensively classified and introduced, and their future development trends are prospected. this survey can provide some guidance for researchers who are interested in the areas like audio synthesis and audio - visual multimodal processing. | arxiv:2108.00443 |
using only lidar or radar an accurate cloud boundary height estimate is often not possible. the combination of lidar and radar can give a reliable cloud boundary estimate in a much broader range of cases. however, also this combination with standard methods still can not measure the cloud boundaries in all cases. this will be illustrated with data from the clouds and radiation measurement campaigns, clara. rain is a problem : the radar has problems to measure the small cloud droplets in the presence of raindrops. similarly, few large particles below cloud base can obscure the cloud base in radar measurements. and the radar reflectivity can be very low at the cloud base of water clouds or in large regions of ice clouds, due to small particles. multiple cloud layers and clouds with specular reflections can pose problems for lidar. more advanced measurement techniques are suggested to solve these problems. an angle scanning lidar can, for example, detect specular reflections, while using information from the radars doppler velocity spectrum may help to detect clouds during rain. | arxiv:physics/0306069 |
large port count spatial optical switches will facilitate flexible and energy efficient data movement in future data communications systems, especially if they are capable of nanosecond - order reconfiguration times. in this work, we demonstrate an 8x8 microring - based silicon photonic switch with software controlled switching. the proposed switch architecture is modular as it assembles multiple identical components with multiplexing / demultiplexing functionalities. the switch is fully non - blocking, has path independent insertion loss, low crosstalk and is straightforward to control. a scalability analysis shows that this architecture can scale to very large port counts. this work represents the first demonstration of real - time firmware controlled switching with silicon photonics devices integrated at the chip scale. | arxiv:1512.09323 |
we investigate the generalisation of quantum search of unstructured and totally ordered sets to search of partially ordered sets ( posets ). two models for poset search are considered. in both models, we show that quantum algorithms can achieve at most a quadratic improvement in query complexity over classical algorithms, up to logarithmic factors ; we also give quantum algorithms that almost achieve this optimal reduction in complexity. in one model, we give an improved quantum algorithm for searching forest - like posets ; in the other, we give an optimal o ( sqrt ( m ) ) - query quantum algorithm for searching posets derived from m * m arrays sorted by rows and columns. this leads to a quantum algorithm that finds the intersection of two sorted lists of n integers in o ( sqrt ( n ) ) time, which is optimal. | arxiv:quant-ph/0702196 |
statistical machine learning algorithms have achieved state - of - the - art results on benchmark datasets, outperforming humans in many tasks. however, the out - of - distribution data and confounder, which have an unpredictable causal relationship, significantly degrade the performance of the existing models. causal representation learning ( crl ) has recently been a promising direction to address the causal relationship problem in vision understanding. this survey presents recent advances in crl in vision. firstly, we introduce the basic concept of causal inference. secondly, we analyze the crl theoretical work, especially in invariant risk minimization, and the practical work in feature understanding and transfer learning. finally, we propose a future research direction in medical image analysis and crl general theory. | arxiv:2210.16034 |
we introduce a newly developed r package aziad for analyzing zero - inflated or zero - altered data. compared with existing r packages, aziad covers a much larger class of zero - inflated and hurdle models, including both discrete and continuous cases. it provides more accurate parameter estimates, along with the corresponding fisher information matrix and confidence intervals. it achieves significantly larger power for model identification and selection. to facilitate the potential users, in this paper we provide detailed formulae and theoretical justifications for aziad, as well as new theoretical results on zero - inflated and zero - altered models. we use simulation studies to show the advantages of aziad functions over existing r packages and provide real data examples and executable r code to illustrate how to use our package for sparse data analysis and model selection. | arxiv:2205.01294 |
certain remnants of a quantum spacetime foam can be modeled by a distribution of defects embedded in a flat classical spacetime. the presence of such spacetime defects affects the propagation of elementary particles. in this article, we show explicitly that both topology and differential structure of the defects are important for the particle motion. specifically, we consider three types of spacetime defects which are described by the same topological manifold $ \ mathbb { r } \ times \ big ( \ mathbb { r } p ^ 3 - \ { \ text { point } \ } \ big ) $ but which are not diffeomorphic to each other. we investigate the propagation of a massless scalar field over the three different manifolds and find different solutions of the \ mbox { klein - - gordon } equation. | arxiv:1404.2901 |
we present an overview of the theory of self - distributive quasigroups, both in the two - sided and one - sided cases, and relate the older results to the modern theory of quandles, to which self - distributive quasigroups are a special case. most attention is paid to the representation results ( loop isotopy, linear representation, homogeneous representation ), as the main tool to investigate self - distributive quasigroups. | arxiv:1505.06609 |
we describe a very general ( nonlinear ) fredholm theory for a new class of ambient spaces, called polyfolds. the basic feature of these new spaces is that in general they may have locally varying dimensions. these new spaces are needed for a functional analytic treatment of nonlinear problems involving analytic limiting behavior. this theory is applicable to gromov - witten and floer theory as well as symplectic field theory. | arxiv:0810.0736 |
we show that the threshold of complete synchronization in a lattice of coupled non - smooth chaotic maps is determined by linear stability along the directions transversal to the synchronization subspace. as a result, the numerically determined synchronization threshold agree with the analytical results previously obtained [ c. anteneodo et al., phys. rev. e 68, 045202 ( r ) ( 2003 ) ] for this class of systems. we present both careful numerical experiments and a rigorous mathematical explanation confirming this fact, allowing for a generalization involving hyperbolic coupled map lattices. | arxiv:0809.0294 |
we prove that a linear growth graph has finitely many horofunctions. this provides a short and simple proof that any finitely generated infinite group of linear growth is virtually cyclic. | arxiv:1608.03727 |
symmetric conformal killing tensors and ( skew - symmetric ) conformal yano - killing tensors for euclidean taub - nut metric are given in explicit form. relations between yano and cyk tensors in terms of conformal rescaling are discussed. | arxiv:gr-qc/0610090 |
we introduce and study multivariate generalizations of the classical bv spaces of jordan, f. riesz and wiener. the family of the introduced spaces contains or is intimately related to a considerable class of function spaces of modern analysis including bmo, bv, morrey spaces and those of sobolev of arbitrary smoothness, besov and triebel - lizorkin spaces. we prove under mild restrictions that the bv spaces of this family are dual and present constructive characterizations of their preduals via atomic decompositions. moreover, we show that under additional restrictions such a predual space is isometrically isomorphic to the dual space of the separable subspace of the related bv space generated by $ c ^ \ infty $ functions. as a corollary we obtain the " two stars theorem " asserting that the second dual of this separable subspace is isometrically isomorphic to the bv space. an essential role in the proofs play approximation properties of the bv spaces under consideration, in particular, weak $ ^ * $ denseness of their subspaces of $ c ^ \ infty $ functions. our results imply the similar ones ( old and new ) for the classical function spaces listed above obtained by the unified approach. | arxiv:1806.08824 |
parameters associated with the collisional perturbation of spectral lines are essential for modeling the absorption of electromagnetic radiation in gas media. the hitran molecular spectroscopic database provides these parameters, although originally they were associated only with the voigt profile parameterization. however, in the hitran2016 and hitran2020 editions, voigt, speed - dependent voigt and hartmann - tran ( ht ) profiles have been incorporated, thanks to the new relational structure of the database. the ht profile was introduced in hitran in 2016 as a recommended profile for the most accurate spectral interpretations and modeling. it was parameterized with a four - temperature - range temperature dependence. since then, however, some features of the ht profile have been revealed that are problematic from a practical perspective. these are : the singular behavior of the temperature dependencies of the velocity - changing parameters when the shift parameter crosses zero and the difficulty in evaluating the former for mixtures. in this article, we summarize efforts to eliminate the above - mentioned problems that led us to recommend using the quadratic speed - dependent hard - collision ( qsdhc ) profile with double - power - law ( dpl ) temperature dependencies. we refer to this profile as a modified hartmann - tran ( mht ) profile. the computational cost of evaluating it is the same as for the ht profile. we give a detailed description of the mht profile ( also including line mixing ) and discuss the representation of its parameters, together with their dpl temperature parametrization adopted in the hitran database. we discuss an efficient algorithm for evaluating this profile and provide corresponding computer codes in several programming languages : fortran, python, matlab, wolfram mathematica, and labview. we also discuss the associated update of the hitran application programming interface ( hapi ). | arxiv:2503.21430 |
a large number of new experimental data on $ b $ decay into two light pesudoscalar ( $ p $ ) mesons have been collected by the lhcb collaboration. besides confirming information on $ b _ { u, d } \ to pp $ decays obtained earlier by b - factories at kek and slac, new information on $ b _ s \ to pp $ and also more decay modes with $ p $ being $ \ eta $ or $ \ eta ' $ have been obtained. using these new data, we perform a global fit for $ b \ to pp $ to determine decay amplitudes in the framework of $ su ( 3 ) / u ( 3 ) $ flavor symmetry. we find that $ su ( 3 ) $ flavor symmetry can explain data well. the annihilation amplitudes are found to be small as expected. several cp violating relations predicted by $ su ( 3 ) $ flavor symmetry are in good agreement with data. current available data can give constraints on the amplitudes which induce $ p = \ eta, \ ; \ eta ' $ decays in the framework of $ u ( 3 ) $ flavor symmetry, and can also determine the $ \ eta - \ eta ' $ mixing angle $ \ theta $ with $ \ theta = ( - 18. 4 \ pm1. 2 ) ^ \ circ $. several $ b \ to pp $ decay modes which have not been measured are predicted with branching ratios accessible at the lhcb. these decays can provide further tests for the framework of $ su ( 3 ) / u ( 3 ) $ flavor symmetry for $ b $ decays. | arxiv:1512.09223 |
we consider a chain of spin - half particles of a finite length, evolved with the mixed - field ising hamiltonian and impose open boundary condition. we simulate the time evolution of entanglement entropy and mutual information following quench from the n \ ' eel state in this system using tensor networks. we find that the entanglement entropy for non - integrable systems saturates to a constant value at late times, however it continues to oscillate for integrable systems. we also find that mutual information peaks as a function of distance between intervals decay faster for non - integrable systems compared to integrable systems, in agreement with the conclusion of \ cite { alba : 2019ybw } for xxz chains. we compare the oscillations in entanglement entropy evolution obtained from simulations in the integrable case with analytic results from quasi - particle picture and find agreement. | arxiv:2402.13558 |
tropical nevanlinna theory, introduced by halburd and southall as a tool to analyze integrability of ultra - discrete equations, studies the growth and complexity of continuous piecewise linear real functions. the purpose of this paper is to extend tropical nevanlinna theory to n - dimensional tropical projective spaces by introducing a natural characteristic function for tropical holomorphic curves, and by proving a tropical analogue of cartan ' s second main theorem. it is also shown that in the 1 - dimensional case this result implies a known tropical second main theorem due to laine and tohge. | arxiv:1401.5584 |
we prove the arithmetic quantum unique ergodicity ( aque ) conjecture for non - degenerate sequences of hecke eigenfunctions on quotients $ \ gamma \ backslash g / k $, where $ g \ simeq \ mathrm { pgl } _ { d } ( \ mathbb { r } ) $, $ k $ is a maximal compact subgroup of $ g $ and $ \ gamma < g $ is a lattice associated to a division algebra over $ \ mathbb { q } $ of prime degree $ d $. more generally, we introduce a new method of proving positive entropy of quantum limits, which applies to higher - rank groups. the result on aque is obtained by combining this with a measure - rigidity theorem due to einsiedler - katok, following a strategy first pioneered by lindenstrauss | arxiv:1606.02267 |
let $ m = ( m _ { ij } ) $ be a symmetric matrix of order $ n $ whose elements lie in an arbitrary field $ \ mathbb { f } $, and let $ g $ be the graph with vertex set $ \ { 1, \ ldots, n \ } $ such that distinct vertices $ i $ and $ j $ are adjacent if and only if $ m _ { ij } \ neq 0 $. we introduce a dynamic programming algorithm that finds a diagonal matrix that is congruent to $ m $. if $ g $ is given with a tree decomposition $ \ mathcal { t } $ of width $ k $, then this can be done in time $ o ( k | \ mathcal { t } | + k ^ 2 n ) $, where $ | \ mathcal { t } | $ denotes the number of nodes in $ \ mathcal { t } $. among other things, this allows one to compute the determinant, the rank and the inertia of a symmetric matrix in time $ o ( k | \ mathcal { t } | + k ^ 2 n ) $. | arxiv:2109.02515 |
the operator nabla, introduced by garsia and the author, plays a crucial role in many aspect of the study of diagonal harmonics. besides giving several new formulas involving this operator, we show how one is lead to representation theoretic explanations for conjectures about the effect of this operator on schur functions. | arxiv:1105.5795 |
let $ m $ be a real bott manifold with k \ " { a } hler structure. using ishida characterization \ cite { i11 } we give necessary and sufficient condition for the existence of the spin - structure on $ m $. in proof we use the technic developed in \ cite { ps16 } and characteristic classes. | arxiv:2207.04879 |
a detailed combinatorial analysis of planar convex lattice polygonal lines is presented. this makes it possible to answer an open question of vershik regarding the existence of a limit shape when the number of vertices is constrained. | arxiv:1606.05062 |
droplets coalescing on flat surfaces tend to end up with the smaller droplet migrating into the larger one. we report a counter - intuitive droplet coalescence pattern on a superhydrophilic cylindrical wire, where the larger droplet is pulled toward the smaller one. consequently, the center of the combined mass significantly moves toward, often beyond, the original location of the smaller droplet. this phenomenon occurs primarily because the viscous friction that a droplet experiences on a cylindrical wire is not positively correlated with the size of the droplet, unlike the droplets coalescing on flat surfaces. we conducted a dimensional analysis based on a mass - spring - damper ( msd ) model. our model predicts a variety of coalescence patterns as a function of the ratio between droplet sizes, and the prediction matches the experimental observation. | arxiv:2211.11094 |
we consider non - linear plane gravitational waves as propagating space - time defects, and construct the burgers vector of the waves. in the context of classical continuum systems, the burgers vector is a measure of the deformation of the medium, and at a microscopic ( atomic ) scale, it is a naturally quantized object. one purpose of the present article is ultimately to probe an alternative way on how to quantize plane gravitational waves. | arxiv:2101.10499 |
semester of chemistry, and one semester of biology. there is a laboratory requirement, usually satisfied by an appropriate class in a course major. the humanities, arts, and social sciences ( hass ) requirement consists of eight semesters of classes in the humanities, arts, and social sciences, including at least one semester from each division as well as the courses required for a designated concentration in a hass division. under the communication requirement, two of the hass classes, plus two of the classes taken in the designated major must be " communication - intensive ", including " substantial instruction and practice in oral presentation ". finally, all students are required to complete a swimming test ; non - varsity athletes must also take four quarters of physical education classes. most classes rely on a combination of lectures, recitations led by associate professors or graduate students, weekly problem sets ( " p - sets " ), and periodic quizzes or tests. while the pace and difficulty of mit coursework has been compared to " drinking from a fire hose ", the freshmen retention rate at mit is similar to other research universities. the " pass / no - record " grading system relieves some pressure for first - year undergraduates. for each class taken in the fall term, freshmen transcripts will either report only that the class was passed, or otherwise not have any record of it. in the spring term, passing grades ( a, b, c ) appear on the transcript while non - passing grades are again not recorded. ( grading had previously been " pass / no record " all freshman year, but was amended for the class of 2006 to prevent students from gaming the system by completing required major classes in their freshman year. ) also, freshmen may choose to join alternative learning communities, such as experimental study group, concourse, or terrascope. mit ' s curriculum encourages students to apply scientific knowledge in practical domains, an idea summarized in the institute motto of mens et manus or " mind and hand. " courses emphasizes uses of engineering knowledge in arenas like product design competitions and control design. in 1969, margaret macvicar founded the undergraduate research opportunities program ( urop ) to enable undergraduates to collaborate directly with faculty members and researchers. students join or initiate research projects ( " urops " ) for academic credit, pay, or on a volunteer basis through postings on the urop website or by contacting faculty members directly. a substantial majority of undergraduates participate. students often become published, file patent applications, and / or launch start - up companies based upon their experience | https://en.wikipedia.org/wiki/Massachusetts_Institute_of_Technology |
automatic forensic image analysis assists criminal investigation experts in the search for suspicious persons, abnormal behaviors detection and identity matching in images. in this paper we propose a person retrieval system that uses textual queries ( e. g., " black trousers and green shirt " ) as descriptions and a one - class generative color model with outlier filtering to represent the images both to train the models and to perform the search. the method is evaluated in terms of its efficiency in fulfilling the needs of a forensic retrieval system : limited annotation, robustness, extensibility, adaptability and computational cost. the proposed generative method is compared to a corresponding discriminative approach. experiments are carried out using a range of queries in three different databases. the experiments show that the two evaluated algorithms provide average retrieval performance and adaptable to new datasets. the proposed generative algorithm has some advantages over the discriminative one, specifically its capability to work with very few training samples and its much lower computational requirements when the number of training examples increases. | arxiv:1611.05915 |
we study the fractal geometry of o ( $ n $ ) loop configurations in two dimensions by means of scaling and a monte carlo method, and compare the results with predictions based on the coulomb gas technique. the monte carlo algorithm is applicable to models with noninteger $ n $ and uses local updates. although these updates typically lead to nonlocal modifications of loop connectivities, the number of operations required per update is only of order one. the monte carlo algorithm is applied to the o ( $ n $ ) model for several values of $ n $, including noninteger ones. we thus determine scaling exponents that describe the fractal nature of o ( $ n $ ) loops at criticality. the results of the numerical analysis agree with the theoretical predictions. | arxiv:cond-mat/0608547 |
a family of graphs $ \ mathcal { f } $ is hereditary if $ \ mathcal { f } $ is closed under isomorphism and taking induced subgraphs. the speed of $ \ mathcal { f } $ is the sequence $ \ { | \ mathcal { f } ^ n | \ } _ { n \ in \ mathbb { n } } $, where $ \ mathcal { f } ^ n $ denotes the set of graphs in $ \ mathcal { f } $ with the vertex set $ [ n ] $. alon, balogh, bollob \ ' { a } s and morris [ the structure of almost all graphs in a hereditary property, jctb 2011 ] gave a rough description of typical graphs in a hereditary family and used it to show for every proper hereditary family $ \ mathcal { f } $ there exist $ \ varepsilon > 0 $ and an integer $ l \ geq 1 $ such that $ $ | \ mathcal { f } ^ n | = 2 ^ { ( 1 - 1 / l ) n ^ 2 / 2 + o ( n ^ { 2 - \ varepsilon } ) }. $ $ the main result of this paper gives a more precise description of typical structure for a restricted class of hereditary families. as a consequence we characterize hereditary families with the speed just above the threshold $ 2 ^ { ( 1 - 1 / l ) n ^ 2 / 2 } $, generalizing a result of balogh and butterfield [ excluding induced subgraphs : critical graphs, rsa 2011 ]. | arxiv:2007.00686 |
we answer a question of calderoni and clay by showing that the conjugation equivalence relation of left orderings of the baumslag - solitar groups $ \ mathrm { bs } ( 1, n ) $ is hyperfinite for any $ n $. our proof relies on a classification of $ \ mathrm { bs } ( 1, n ) $ ' s left - orderings via its one - dimensional dynamical realizations. we furthermore use the effectiveness of the dynamical realizations of $ \ mathrm { bs } ( 1, n ) $ to study algorithmic properties of the left - orderings on $ \ mathrm { bs } ( 1, n ) $. | arxiv:2405.08442 |
students the opportunity to observe scientific processes, hypothesize, and observe results. this dimension highlights the empirical methods of science. the dimension entitled " crosscutting concepts " emphasizes the understanding of key themes within the field of science. the " crosscutting concepts " are themes that are consistently relevant throughout many different scientific disciplines, such as the flow of energy / matter, cause / effect, systems / system practices, patterns, the relationship between structure and function, and stability / change. the purpose of outlining these key themes relates to generalized learning, meaning that the effectiveness of these themes could lie in the fact that these concepts are important throughout all of the scientific disciplines. the intention is that by learning them, students will create a broad understanding of science. the dimension entitled " disciplinary core ideas " outlines a set of key ideas for each scientific field. for example, physical science has a certain set of core ideas laid out by the framework. = = = = science education and common core = = = = common core education standards emphasize on reading, writing, and communication skills. the purpose of these standards for english and mathematics was to create measurable goals for student learning that are aligned with the standards in place in other nations, such that students in the united states become prepared to succeed at a global level. it is meant to set standards for academics that are rigorous in nature and prepare students for higher education. it is also outlined that students with disabilities must be properly accommodated for under common core standards via an individualized education plan ( iep ). under these standards, the comprehension of scientific writing has become an important skill for students to learn through textbooks. = = = = science education strategies = = = = evidence suggests, however, that students learn science more effectively under hands - on, activity and inquiry based learning, rather than learning from a textbook. it has been seen that students, in particular those with learning disabilities, perform better on unit tests after learning science through activities, rather than textbook - based learning. thus, it is argued that science is better learned through experiential activities. additionally, it has reported that students, specifically those with learning disabilities, prefer and feel that they learn more effectively through activity - based learning. information like this can help inform the way science is taught and how it can be taught most effectively for students of all abilities. the laboratory is a foundational example of hands - on, activity - based learning. in the laboratory, students use materials to observe scientific concepts and phenomena. the laboratory in science education can include | https://en.wikipedia.org/wiki/Science_education |
we investigate possible quantifications of strictly singular operators, $ l _ { p } $ - strictly singular operators, $ c _ { 0 } $ - strictly singular operators, strictly cosingular operators, $ l _ { p } $ - strictly cosingular operators. we prove quantitative, even strengthening versions of well - known results about relationships of these five classes of operators and compact, weakly compact, unconditionally converging operators. | arxiv:1608.07495 |
evaluation of the effective - range parameters for the $ t _ { cc } ^ + $ state in the lhcb model is examined. the finite width of $ d ^ * $ leads to a shift of the expansion point into the complex plane to match analytical properties of the expanded amplitude. we perform an analytic continuation of the three - body scattering amplitude to the complex plane in a vicinity of the branch point and develop a robust procedure for computation of the expansion coefficients. the results yield a nearly - real scattering length, and two contributions to the the effective range which have not been accounted before. | arxiv:2203.04622 |
the na49 fixed - target experiment studied high energy - density matter produced in nucleus - nucleus reactions at the cern sps. in central pb + pb collisions at 158a gev the energy density at the early stage substantially exceeds the threshold for quark deconfinement predicted by lattice qcd. the produced matter shows strong transverse and longitudinal flow. ratios of yields of produced particles are approximately consistent with statistical equilibration. an energy scan through the sps range revealed structure in the energy dependence of pion and kaon yields as well as of the inverse slopes of transverse mass distributions. these features suggest that a deconfined phase starts to be produced at around 30a gev in central pb + pb collisions. the analysis of fluctuations and correlations has not yet provided evidence for the predicted critical point of qcd. | arxiv:nucl-ex/0612008 |
the precise analysis of the variance of the profile of a suffix tree has been a longstanding open problem. we analyze three regimes of the asymptotic growth of the variance of the profile of a suffix tree built from a randomly generated binary string, in the nonuniform case. we utilize combinatorics on words, singularity analysis, and the mellin transform. | arxiv:1605.03390 |
particle impaction in the super heater geometry found in the municipal solid waste incinerator ( mswi ) of gks in schweinfurt, germany, has been investigated. by using direct numerical simulations for the fluid flow, inertial particles coupled to the fluid through the classical stokes ' drag law have been tracked. focus has been on the effect of flow velocity, and it is shown that decreasing the flow velocity will drastically decrease the impaction efficiency for some particle radii. finally particle size distribution measurements are presented and used to find quantitative mass fluxes both on the front and the back side of the tubes in the super heater tube bundle. | arxiv:1008.5040 |
the concept of em drive has attracted much attention and groups of work have been conducted to prove or verify it, of which the published experimental outcome is criticized in great details while the theoretical foundation has not been discussed. the present essay investigates on the theoretical derivations of the net thrust in the em drive and reveals the self - contradiction arising at the very start, when the law of conservation of momentum was utilized and opposed simultaneously. | arxiv:1801.02975 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.