abstract stringlengths 3 192k | title stringlengths 4 857 |
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many theories beyond the standard model involve an extra u (1 ) gauge group. the resulting gauge boson u , in general mixed with the z and the photon, may be massless or very light and very weakly coupled. it may be viewed as a generalized dark photon interacting with matter through a linear combination [ɛqq +ɛbb +ɛll ... | microscope limits for new long-range forces and implications for unified theories |
the physics program accessible in $e^+e^-$ collisions at the future circular collider (fcc-ee) is summarized. the fcc-ee aims at collecting multi-ab$^{-1}$ integrated luminosities in $e^+e^-$ at $\sqrt{s}$ = 90, 160, 240, and 350 gev, yielding 10$^{12}$ z bosons, 10$^{8}$ w$^+$w$^-$ pairs, 10$^{6}$ higgs bosons and $4\... | physics at the fcc-ee |
we present the full basis of effective operators relevant for dark matter direct detection, up to and including operators of mass dimension seven. we treat the cases where dark matter is either a dirac fermion, a majorana fermion, a complex scalar, or a real scalar, allowing for dark matter to furnish a general represe... | effective field theory for dark matter direct detection up to dimension seven |
we present a class of models in which the coupling of the photon to an ultralight scalar field that has a time-dependent vacuum expectation value causes the fine structure constant to oscillate in time. the scalar field is assumed to constitute all or part of the observed dark matter. its mass is protected against radi... | time-varying fine structure constant from naturally ultralight dark matter |
we discuss how to consistently use effective field theories (efts) to set universal bounds on heavy-mediator dark matter at colliders, without prejudice on the model underlying a given effective interaction. we illustrate the method for a majorana fermion, universally coupled to the standard model quarks via a dimensio... | robust collider limits on heavy-mediator dark matter |
scalar-tensor theories offer the prospect of explaining the cosmological evolution of the universe through an effective description of dark energy as a quantity with a non-trivial evolution. in this work, we investigate this feature of scalar-tensor theories in the teleparallel gravity context. teleparallel gravity is ... | teleparallel scalar-tensor gravity through cosmological dynamical systems |
nuclear scattering events with large momentum transfer in atomic, molecular, or solid-state systems may result in electronic excitations. in the context of atomic scattering by dark matter (dm), this is known as the migdal effect, but the same effect has also been studied in molecules in the chemistry and neutron scatt... | molecular migdal effect |
anais is a direct detection dark matter experiment aiming at the testing of the dama/libra annual modulation result, which, for about two decades, has neither been confirmed nor ruled out by any other experiment in a model independent way. anais -112 , consisting of 112.5 kg of sodium iodide crystals, has been taking d... | first results on dark matter annual modulation from the anais-112 experiment |
dark matter (dm) scattering with nuclei in solid-state systems may produce elastic nuclear recoil at high energies and single-phonon excitation at low energies. when the dm momentum is comparable to the momentum spread of nuclei bound in a lattice, q0=√{2 mnω0 } where mn is the mass of the nucleus and ω0 is the optical... | dark matter detection with bound nuclear targets: the poisson phonon tail |
among the numerous proposals to explain the nature of dark matter, there is the weakly interacting massive particle (wimp) scenario, which is based on a simple assumption that dark matter was in thermal equilibrium in the early hot universe, and its particles have mass and interactions not too different from the massiv... | search for dark matter at colliders |
dark energy equation of state w (z ) parametrizations with two parameters and given monotonicity are generically either convex or concave functions. this makes them suitable for fitting either freezing or thawing quintessence models but not both simultaneously. fitting a data set based on a freezing model with an unsui... | comparison of thawing and freezing dark energy parametrizations |
here we consider a flat frw universe whose horizon entropy meets the rényi entropy of nonextensive systems. in our model, the ordinary energy-momentum conservation law is not always valid. by applying the clausius relation as well as the cai-kim temperature to the apparent horizon of a flat frw universe, we obtain modi... | accelerated cosmos in a nonextensive setup |
a search is conducted for new physics in a final state containing a photon and missing transverse momentum in proton-proton collisions at √{s}=13 tev. the data collected by the cms experiment at the cern lhc correspond to an integrated luminosity of 12.9 fb-1. no deviations are observed relative to the predictions of t... | search for new physics in the monophoton final state in proton-proton collisions at √{s}=13 tev |
this paper reports that the introduction of elemental red phosphorus (rp) into tio2 can shift the light absorption ability from the uv to the visible region, and confirmed that the optimal rp loading and milling time can effectively improve the visible light driven-photocatalytic activity of tio2. the resulting rp-tio2... | highly visible light responsive, narrow band gap tio2 nanoparticles modified by elemental red phosphorus for photocatalysis and photoelectrochemical applications |
we report the findings of our extensive study of the spectra of flavoured mesons in lattice gauge theories with symplectic gauge group and fermion matter content treated in the quenched approximation. for the $sp(4)$, $sp(6)$, and $sp(8)$ gauge groups, the (dirac) fermions transform in either the fundamental, or the 2-... | on the spectrum of mesons in quenched $sp(2n)$ gauge theories |
the dark matter may consist not of one elementary particle but of different species, each of them contributing a fraction of the observed dark matter density. a major theoretical difficulty with this scenario — dubbed multi-component dark matter — is to explain the stability of these distinct particles. imposing a sing... | multi-component scalar dark matter from a zn symmetry: a systematic analysis |
cosmological parameter inference has been dominated by the bayesian approach for the past two decades, primarily due to its computational efficiency. however, the bayesian approach involves integration of the posterior probability and therefore depends on both the choice of model parametrisation and the choice of prior... | prospect: a profile likelihood code for frequentist cosmological parameter inference |
we study capability of the ilc beam dump experiment to search for new physics, comparing the performance of the electron and positron beam dumps. the dark photon, axion-like particles, and light scalar bosons are considered as new physics scenarios, where all the important production mechanisms are included: electron-p... | new physics searches at the ilc positron and electron beam dumps |
recent warming in the arctic, which has been amplified during the winter1-3, greatly enhances microbial decomposition of soil organic matter and subsequent release of carbon dioxide (co2)4. however, the amount of co2 released in winter is not known and has not been well represented by ecosystem models or empirically ba... | large loss of co2 in winter observed across the northern permafrost region |
methane emissions were measured at 6650 sites across six major oil and gas producing regions in canada to examine regional emission trends, and to derive an inventory estimate for canada's upstream oil and gas sector. emissions varied by fluid type and geographic region, with the heavy oil region of lloydminster rankin... | methane emissions from upstream oil and gas production in canada are underestimated |
north american leaders recently committed to reducing methane emissions from the oil and gas sector, but information on current emissions from upstream oil and gas developments in canada are lacking. this study examined the occurrence of methane plumes in an area of unconventional natural gas development in northwester... | mobile measurement of methane emissions from natural gas developments in northeastern british columbia, canada |
permafrost soils currently store approximately 1672 pg of carbon (c), but as high latitudes warm, this temperature-protected c reservoir will become vulnerable to higher rates of decomposition. in recent decades, air temperatures in the high latitudes have warmed more than any other region globally, particularly during... | increased wintertime co2 loss as a result of sustained tundra warming |
soil respiration (i.e. from soils and roots) provides one of the largest global fluxes of carbon dioxide (co2) to the atmosphere and is likely to increase with warming, yet the magnitude of soil respiration from rapidly thawing arctic-boreal regions is not well understood. to address this knowledge gap, we first compil... | soil respiration strongly offsets carbon uptake in alaska and northwest canada |
energy development in southeastern saskatchewan, canada, is unique because conventional and unconventional oil and gas production is co-located. mobile surveys are ideal for understanding emissions in this area because the overlap of production makes it difficult for airborne or satellite-based methods to differentiate... | methane emissions from conventional and unconventional oil and gas production sites in southeastern saskatchewan, canada |
the oil and gas industry is canada's largest contributor to national methane (ch4) emissions. to quantify the input of active and inactive (suspended and abandoned) oil and gas infrastructure to regional ch4 budgets, we conducted truck-based measurements (transect-based and otm 33a) with a greenhouse gas analyzer, comp... | active and inactive oil and gas sites contribute to methane emissions in western saskatchewan, canada |
lakes may function as either sinks or sources of co2. their response to climate change is uncertain, as we lack continuous data of lake co2 efflux and its drivers. this is especially true in the littoral zone of lakes, which can be very dynamic from the continuous injection and remobilization of terrestrial nutrients. ... | spatiotemporal variability in lake-atmosphere net co2 exchange in the littoral zone of an oligotrophic lake |
aggressive reductions of oil and gas sector methane, a potent greenhouse gas, have been proposed in canada. few large-scale measurement studies have been conducted to confirm a baseline. this study used a vehicle-based gas monitoring system to measure fugitive and vented gas emissions across lloydminster (heavy oil), p... | methane emissions from contrasting production regions within alberta, canada: implications under incoming federal methane regulations |
salt marshes are ecologically sensitive ecosystems where mercury (hg) methylation and biomagnification can occur. understanding the mechanisms controlling gaseous hg flux from salt marshes is important to predict the retention of hg in coastal wetlands and project the impact of environmental change on the global hg cyc... | gaseous mercury flux from salt marshes is mediated by solar radiation and temperature |
during its run 2 (2015-2018), the large hadron collider (lhc) operated at almost twice higher energy, and provided pb-pb collisions with an order of magnitude higher luminosity, than in the previous run 1. in consequence, the power of the secondary beams emitted from the interaction points by the bound-free pair produc... | bound-free pair production from nuclear collisions and the steady-state quench limit of the main dipole magnets of the cern large hadron collider |
tree provenance trials consist of a variety of seed sources (or provenances) planted at several test sites across the range of a species. the resulting plantations are typically measured periodically to investigate provenance performance in relation to abiotic conditions, particularly climate. these trials are expensiv... | a compilation of north american tree provenance trials and relevant historical climate data for seven species |
in this contribution, a comparison between different permutation entropies as classifiers of electroencephalogram (eeg) records corresponding to normal and pre-ictal states is made. a discrete probability distribution function derived from symbolization techniques applied to the eeg signal is used to calculate the tsal... | classification of normal and pre-ictal eeg signals using permutation entropies and a generalized linear model as a classifier |
oral epithelial dysplasia (oed) is a histopathologically-defined, potentially premalignant condition of the oral cavity. the rate of transformation to frank carcinoma is relatively low (12% within 2 years) and prediction based on histopathological grade is unreliable, leading to both over- and under-treatment. alternat... | prediction of malignant transformation in oral epithelial dysplasia using infrared absorbance spectra |
we present a dynamic physico-economic model of earth orbit use with endogenous satellite collision risk to study conditions under which debris-producing collisions between orbiting bodies result in debris growth that may render earth's orbits unusable, an outcome known as kessler syndrome. we characterize the dynamics ... | the economics of orbit use: open access, external costs, and runaway debris growth |
in 2002, bandt and pompe [phys. rev. lett. 88, 174102 (2002)] introduced a successfully symbolic encoding scheme based on the ordinal relation between the amplitude of neighboring values of a given data sequence, from which the permutation entropy can be evaluated. equalities in the analyzed sequence, for example, repe... | bandt-pompe symbolization dynamics for time series with tied values: a data-driven approach |
paper examines the sources of uncertainty for the forced diffusion (fd) chamber soil respiration (rs) measurement technique and demonstrates a protocol for uncertainty quantification that could be appropriate with any soil flux technique. here we sought to quantify and compare the three primary sources of uncertainty i... | a practical approach for uncertainty quantification of high-frequency soil respiration using forced diffusion chambers |
comparison of (a) h&e image of oral squamous cell carcinoma with (b) ratio of absorbance at 1252 cm−1/1285 cm−1 and (c) pseudo-coloured labelled image of seven types of tissue found in oral tissue. a machine learning algorithm (mla) has predicted the prognosis of oral potentially malignant lesions and discriminated... | metric-based analysis of ftir data to discriminate tissue types in oral cancer |
vast amounts of methane (ch4) stored in submarine sediments are susceptible to release in a warming arctic, further exacerbating climate change in a positive feedback. it is therefore critical to monitor ch4 over pan-regional scales to detect early signs of ch4 release. however, our ability to monitor ch4 is hampered i... | sea-air methane flux estimates derived from marine surface observations and instantaneous atmospheric measurements in the northern labrador sea and baffin bay |
biogeochemical processes driving the spatial variability of soil co2 production and flux are well studied, but little is known about the variability in the spatial distribution of the stable carbon isotopes that make up soil co2, particularly in complex terrain. spatial differences in stable isotopes of soil co2 could ... | spatial and seasonal variabilities of the stable carbon isotope composition of soil co2 concentration and flux in complex terrain |
we develop a flexible gaussian process (gp) framework for learning the covariance structure of age- and year-specific mortality surfaces. utilizing the additive and multiplicative structure of gp kernels, we design a genetic programming algorithm to search for the most expressive kernel for a given population. our comp... | expressive mortality models through gaussian process kernels |
despite oil and gas related methane (ch4) emissions being the largest anthropogenic source of ch4 in canada, there are few measurement studies on such emissions to date. that being said, understanding the emissions footprint of different development types is becoming increasingly important in canada, as the oil and gas... | fugitive and vented methane emissions surveying on the weyburn co2-eor field in southeastern saskatchewan, canada |
the impact fragmentation model has been used by the aerospace corporation for more than 25 years to analyze orbital altitude explosions and hypervelocity collisions. the model is semi-empirical, combining mass, energy and momentum conservation laws with empirically derived relationships for fragment characteristics suc... | impact fragmentation model developments |
winter soil carbon dioxide (co2) respiration is a significant and understudied component of the global carbon (c) cycle. winter soil co2 fluxes can be surprisingly variable, owing to physical factors such as snowpack properties and wind. this study aimed to quantify the effects of advective transport of co2 in soil-sno... | explaining co2 fluctuations observed in snowpacks |
in weyburn, saskatchewan, carbon dioxide (co2) is injected into the weyburn oilfield for enhanced oil recovery (eor). cenovus energy inc. operates more than 1000 active wells, processing plants, and hundreds of kilometres of pipeline infrastructure over a >100 km2 area. while vehicle-based atmospheric detection of g... | atmospheric monitoring and detection of fugitive emissions for enhanced oil recovery |
physical soil properties create lags between temperature change and corresponding soil responses, which obscure true q10 (temperature sensitivity) values and other biophysical parameters such as depth of production. this study examines an inversion approach for estimating q10 and e-folding depth of co2 production (zp) ... | an inversion approach for determining distribution of production and temperature sensitivity of soil respiration |
around the world, coral reefs are in decline. recent interest has focussed on the impacts of global warming/climate change, but the decline started long before the influence of climate change became apparent, driven by anthropogenic factors such as sedimentation, nutrient increase, and overfishing. these continue with ... | cage aquaculture in the persian gulf: a cautionary tale for iran and the world |
vehicle-based measurements of wind speed and direction are presently used for a range of applications, including gas plume detection. many applications use mobile wind measurements without knowledge of the limitations and accuracy of the mobile measurement system. our research objective for this field-simulation study ... | using computational fluid dynamics and field experiments to improve vehicle-based wind measurements for environmental monitoring |
active debris removal (adr) methods are being developed due to a growing concern about the congestion on-orbit and sustainability of spaceflight. this study examined the probability of an on-orbit collision between an adr target, whilst being de-orbited, and all the objects in the public catalogue published by the us s... | considering the collision probability of active debris removal missions |
a machine learning algorithm (mla) has been applied to a fourier transform infrared spectroscopy (ftir) dataset previously analysed with a principal component analysis (pca) linear discriminant analysis (lda) model. this comparison has confirmed the robustness of ftir as a prognostic tool for oral epithelial dysplasia ... | prediction of malignant transformation in oral epithelial dysplasia using machine learning |
gliomas are one of the most common types of brain tumors. given low survival and high treatment resistance rates, particularly for high grade gliomas, there is a need for specific biomarkers that can be used to stratify patients for therapy and monitor treatment response. recent work has demonstrated that metabolic rep... | characterization of dysregulated glutamine metabolism in human glioma tissue with 1h nmr |
the canadian forest fire weather index (fwi) system requires spatially continuous, gridded weather data for temperature, relative humidity, wind speed, and precipitation. reliable estimates of the canadian fwi system components are needed to ensure the safety of communities, resources, and ecosystems. the quality of th... | optimal cross-validation strategies for selection of spatial interpolation models for the canadian forest fire weather index system |
as oil and gas wells age and the number of wells drilled increases to meet demand, we may see more instances of fugitive soil gas migration (gm) and associated methane (ch4) emissions. due to the immense spatiotemporal variability of soils and uncertainty in measurement practice, the detection and quantification of gm ... | soil surface flux measurements are a reliable means for assessing fugitive gas migration across soils and seasons |
we report changes in the genomic landscape in the development of head and neck squamous cell carcinomas hnscc from potentially premalignant lesions (ppols) to malignancy and lymph node metastases. likely pathological mutations predominantly involved a relatively small set of genes reported previously (tp53, kmt2d, cdkn... | analysis of head and neck carcinoma progression reveals novel and relevant stage-specific changes associated with immortalisation and malignancy |
earth system scientists working with radiocarbon in organic samples use a stable carbon isotope (δ13c) correction to account for mass-dependent fractionation, but it has not been evaluated for the soil gas environment, wherein both diffusive gas transport and diffusive mixing are important. using theory and an analytic... | technical note: isotopic corrections for the radiocarbon composition of co2 in the soil gas environment must account for diffusion and diffusive mixing |
indemn is an object-oriented program dedicated to the modeling of the evolution of the densities of space objects. following the work achieved by d. kessler (1978) and by other authors more recently (g. l. somma, iac 2016, a6-ip3; a. rossi, dpps 2004, 197), the dynamical model is based on a source and sink approach for... | collision risk prediction for constellation design |
this article addresses the growing problems of space debris elevating the increased risk of orbital collisions as well as the difficulty of accurate space situational awareness, especially with regard to smaller space debris. these problems of space situational awareness (ssa) and space traffic management (stm) will be... | a path forward to better space security: finding new solutions to space debris, space situational awareness and space traffic management |
the united nations has addressed the concept of sustainable development on earth in a number of global summits and fora for the past 40 years. extending the concept of sustainability to outer space is a much more recent development, arising from the realization that the earth's orbital space environment constitutes a f... | the un copuos guidelines for the long-term sustainability of outer space activities |
monitoring is cited as a mechanism by which operators can drive public acceptance in co2 geosequestration and energy projects. in this synthesis study we inter-compared a broad suite of geochemical monitoring indicators, to identify which could contribute best to an affordable, yet effective, monitoring system. we exam... | using the kerr investigations at weyburn to screen geochemical tracers for near-surface detection and attribution of leakage at ccs/eor sites |
independent component analysis (ica) is popular in many applications, including cognitive neuroscience and signal processing. due to computational constraints, principal component analysis is used for dimension reduction prior to ica (pca+ica), which could remove important information. the problem is that interesting i... | linear non-gaussian component analysis via maximum likelihood |
independent component analysis (ica) is an unsupervised learning method popular in functional magnetic resonance imaging (fmri). group ica has been used to search for biomarkers in neurological disorders including autism spectrum disorder and dementia. however, current methods use a principal component analysis (pca) s... | group linear non-gaussian component analysis with applications to neuroimaging |
the earth's orbital space environment constitutes a finite resource that is being used by an increasing number of states, international intergovernmental organizations and non-governmental entities. the proliferation of space debris, the increasing complexity of space operations, the emergence of large constellations a... | development of an international compendium of guidelines for the long-term sustainability of outer space activities |
space debris simulations show that if current space launches continue unchanged, spacecraft operations might become difficult in the congested space environment. it has been suggested that active debris removal (adr) might be necessary in order to prevent such a situation. selection of objects to be targeted by adr is ... | impact of high-risk conjunctions on active debris removal target selection |
over the last several decades, the growing amount of space debris has increased the hazard of in-orbit collision between operational satellites and space debris. as the impact with small fragments could partially or completely damage a satellite, an effective method to quickly quantify the risk posed by space debris is... | probability of collision for a newly generated debris cloud using subset simulation technique |
an amendment to this paper has been published and can be accessed via a link at the top of the paper. | author correction: large loss of co2 in winter observed across the northern permafrost region |
the navigation satellite constellations in medium-earth orbit exist in a background of third-body secular resonances stemming from the perturbing gravitational effects of the moon and the sun. the resulting chaotic motions, emanating from the overlapping of neighboring resonant harmonics, induce especially strong pertu... | diffusive chaos in navigation satellites orbits |
currently, a tremendous amount of space debris in earth's orbit imperils operational spacecraft. it is essential to undertake risk assessments of collisions and predict dangerous encounters in space. however, collision predictions for an enormous amount of space debris give rise to large-scale computations. in this pap... | a parallel algorithm for the initial screening of space debris collisions prediction using the sgp4/sdp4 models and gpu acceleration |
transparency and confidence-building measures (tcbms) are a set of tools designed to display, predict and discipline states' behaviour with respect to maintaining the security of space. with intentional and unintentional threats to the peaceful use of space on the rise, there is a growing international consensus on the... | transparency and confidence-building measures for space security |
the year 2017 as the year of the 50th anniversary of the outer space treaty witnesses ongoing discussions about the governance of space activities. the unispace+50 process directly addresses relevant topics in this context, in particular through its thematic priority 2 "the legal regime of outer space governance". in p... | a gradual approach towards space traffic management: the contribution of unisapce+50 |
intracranial pressure (icp) is one of the main neuromonitories used today to guide the treatment of acute neurological patients in the intensive care unit (icu). within this article the complexity of periods of intracranial hypertension is evaluated and compared with periods of stable intracranial tension. using the mu... | the complexity of intracranial pressure as an indicator of cerebral autoregulation |
the collision probability between an operational spacecraft and a population of space debris is investigated. by dividing the 3-dimensional operational space of the spacecraft into several space volume cells (svc) and proposing a boundary selection method to calculate the collision probability in each svc, the distribu... | collision risk investigation for an operational spacecraft caused by space debris |
carbon capture and storage (ccs) is playing a greater role in reducing co2 emissions. the aquistore project at estevan, saskatchewan, canada is an operational ccs demonstration and research site. surface soil gas geochemistry is one method of measurement, monitoring, and verification (mmv) techniques used for detection... | a meta-analysis of the surface soil gas measurement monitoring and verification (mmv) program at the aquistore project |
independent component analysis (ica) decomposes multivariate data into mutually independent components (ics). the ica model is subject to a constraint that at most one of these components is gaussian, which is required for model identifiability. linear non-gaussian component analysis (lngca) generalizes the ica model t... | optimization and testing in linear non-gaussian component analysis |
appropriate diagnosis and treatment of epilepsy is a main public health issue. patients suffering from this disease often exhibit different physical characterizations, which result from the synchronous and excessive discharge of a group of neurons in the cerebral cortex. extracting this information using eeg signals is... | a new algorithm for epilepsy seizure onset detection and spread estimation from eeg signals |
the space debris problematic is directly linked to the in-orbit collision risk between artificial satellites. with the increase of the space constellation projects, a multiplication of multi-payload launches should occur. in the specific cases where many satellites are injected into orbit with the same launcher upper s... | optimization of constellation jettisoning regards to short term collision risks |
. the growing micrometeoroid and orbital debris (mmod) environment in earth orbit poses an increasing risk not only to active satellites but also to the general public. of particular concern are the objects in low earth orbit (leo) which have the potential for catastrophic consequence upon entry and collision with vuln... | a novel method for prediction and warning for uncontrolled re-entry object impact |
astroscale's core mission objectives encompass a range of rendezvous and proximity operation (rpo) focussed activities, including end-of-life (eol) services, active debris removal (adr) capabilities, spacecraft life extension (lex) and space-based 'in-situ space situational awareness' (issa). these missions are not onl... | exploration of opportunities to advance ground-based and space-based ssa systems through in-orbit demonstration missions |
in boreal forests, which contain large stocks of terrestrial carbon (c), fires have been increasing and are expected to continue to do so as the climate becomes warmer and dryer. here we studied the indirect, long-term effects of fire on ecosystem c cycling via changes in stand density, organic layer and thaw depth in,... | long-term impacts of fire on permafrost vulnerability and c loss in siberian larch forests |
commencing january 2020, new canadian federal and alberta provincial regulations will require oil and gas (o&g) producers to inspect upstream wells and facilities for fugitive methane emissions one to three times annually. the standard detection technique is optical gas imaging (ogi), however o&g producers can ... | preparing for 2020: trialling an alternative fugitive leak detection program at an upstream energy development in alberta, canada |
most conjunctions between earth-orbiting satellites involve unknown objects, typically debris created by explosions or collisions. this study formulates methods to estimate probabilities of collision and fragmentation for such conjunctions, which depend on the estimated sizes and masses of the unknown objects. analysis... | satellite collision and fragmentation probabilities using radar-based size and mass estimates |
below 600 km, drag is the largest source of uncertainty for satellite and debris orbit prediction. with an increasing number of satellites in low-earth orbit, accurate observations of the atmospheric mass density are required to improve models of the thermosphere with applications in satellite lifetime predictions, col... | embedded cold atom accelerometer for atmospheric drag measurement |
anthropogenic methane emissions are generated in several economic sectors, including agriculture, waste management, oil and gas production, and others. canada is one of the world's largest oil and gas producers, ranks in the top-25 for agricultural production, and is the world's largest waste producer per capita. as a ... | quantification of methane emissions from anthropogenic sources: a case study in canada |
in order to describe the risk in space, the european space agency releases an annual environment report containing numbers and statistics concerning the debris population and space activities in general. since 2021, the risk in low earth orbit is described also from the perspective of conjunction statistics. for this, ... | statistical analysis of conjunctions in low earth orbit |
in the next years, the space debris population is expected to progressively grow due to in-space collisions and break-up events; in addition, anti-satellite tests can further affect the debris environment by generating large clouds of fragments. the simulation of these events allows identifying the main parameters affe... | simulation of in-space fragmentation events |
we aim to provide satellite operators and researchers with an efficient and effective means for evaluating collision risk during the design process of mega-constellations as well as insight into how the dynamical placement of orbiting systems can greatly reduce collision risk and the need for avoidance maneuvers. curre... | assessing and minimizing collisions in satellite mega-constellations |
in an increasingly dense space environment, collision avoidance has become an essential task in satellite operations. with the trend going towards large mega-constellations, automated procedures may relieve the burden on human operators. this work presents the application of machine learning methods to collision risk a... | implementation and comparison of data-based methods for collision avoidance in satellite operations |
the space debris has been exponentially increasing and their orbital decay takes a very long time. space debris possesses a high amount of kinetic energy as they are moving with orbital velocity. they cause severe damage to active satellites by collision and their removal becomes necessary. there are many space debris ... | dynamics of morphing robotic arm with space debris capture |
two controversial tenets of metapopulation biology are whether patch quality and the surrounding matrix are more important to turnover (colonisation and extinction) than biogeography (patch area and isolation) and whether factors governing turnover during equilibrium also dominate nonequilibrium dynamics. we tested bot... | stability of patch‑turnover relationships under equilibrium and nonequilibrium metapopulation dynamics driven by biogeography |
the number of companies aiming to launch mega con- stellations into space is increasing. the majority of them are supposed to be deployed in low earth orbit (leo) regions where the population of space debris is most con- centrated. this change in the industry requires develop- ments in collision risk analysis since, in... | effect of mega constellations on collision risk in space |
as anthropogenic climate change warms the arctic, organic carbon (c) trapped in permafrost is at an increased risk of being released to the atmosphere as carbon dioxide (co2). at the same time, higher rates of decomposition may increase nutrient availability and enhance plant growth, leading to an uptake of c that may ... | long-term nutrient fertilization increases co2 loss in arctic tundra |
collisions between rocket bodies and non-operational satellites are the most significant source of debris-generating risk in leo. we perform a statistical analysis of collision risk for objects in these clusters using leolabs and cspoc data sources. | collision risk assessment for derelict objects in low-earth orbit |
stable isotopes are commonly used to understand how physical and biological processes mediate the exchange of carbon between terrestrial ecosystems and the atmosphere. numerous studies have described fundamental relationships between environmental variables, the carbon isotopic composition (δ13c) of recently assimilate... | landscape variability of the stable carbon isotope composition of soil co2 concentrations and flux in complex terrain |
soil surface flux measurements integrate respiration across steep vertical gradients of soil texture, moisture, temperature, and carbon substrates. although there are benefits to integrating complex soil processes in a single surface measure, i.e. for constructing soil carbon budgets, one serious drawback of studying o... | can the gradient method improve our ability to predict soil respiration? |
we propose the use of statistical emulators for the purpose of valuing mortality-linked contracts in stochastic mortality models. such models typically require (nested) evaluation of expected values of nonlinear functionals of multi-dimensional stochastic processes. except in the simplest cases, no closed-form expressi... | statistical emulators for pricing and hedging longevity risk products |
satellite constellations represent a new paradigm of space activities, with vast numbers of smaller satellites operated in the so-called newspace industry. with the tide of potential applications and benefits to mankind come risks, notably that of the increased population of low earth orbit and potential for increases ... | legal aspects relating to satellite constellations |
geosynchronous orbit (geo) space environment model of the orbital targets with a size above 10 cm was established according to the amended data and space density. the situation of satellite explosion on geo is simulated, including the number of fragments generated by the explosion, the size distribution as well as the ... | short-term effect of intelsat-29e explosion on geo environment |
a study conducted in 2016 explored a mission to demonstrate the preservation and maintenance of geostationary orbit which could be undertaken with a single ariane launch. the mission, called necropolis, would use two spacecraft; a "hunter" spacecraft to collect non-functional satellites which pose a threat to the geosy... | a mission to demonstrate the preservation of the geostationary orbit |
in the era of leo mega-constellations earth nearest orbits are getting more populated with operational and non-operational spacecraft every year. this will dramatically increase the risk of collisions with consequent further creation of debris. 10 % of failed satellites have been estimated within large constellations, ... | gripper for in-orbit servicing operations |
in recent years, the number of space debris is increasing rapidly, threatening the safety of spacecraft. more and more spacecraft are at risk of colliding with space debris, which may cause air leakages on the sealed container of spacecraft. this is a huge danger for spacecraft and astronauts. in this paper, a leak sou... | leak source beam-forming location of spacecraft in orbit based on dispersion characteristics of lamb wave |
estimation of annual soil co2 emission is not simple due to the winter contribution. further, change in the snow-covered period and frequency in measuring winter co2 efflux leads to inadequately estimate the annual carbon budget. it is not easy to quantify the annual soil carbon emission in response to recently drastic... | quantification of annual soil co2 emission in unburned and burned black spruce forest of interior alaska |
abrupt permafrost thawing is expected to release large amounts of greenhouse gasses to the atmosphere, creating a positive feedback to climate warming. there is, however, still large uncertainty in the timing, duration, magnitude, and mechanisms controlling this process, which hampers accurate quantification of permafr... | long lasting greenhouse gas emissions beyond abrupt permafrost thaw event in permafrost peatlands |
with the global commercialization of space, objects are being launched into earth's orbit faster than natural ef- fects are deorbiting them. orbital debris is dangerous, as the high velocities of orbiting objects typically results in fatal collision events for both parties involved, and cas- cading collisions between o... | space debris removal with sub-tethered net: a feasibility study and preliminary design |
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