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Low Earth Orbit (LEO) satellite constellations are emerging as a key component of non-terrestrial networks due to their low-latency and high-capacity communication capabilities. However, satellites in these orbits are characterized by a small coverage footprint and high orbital velocity compared to those in higher orbits. This results in constantly changing and dynamic constellations that require smart design of orbital parameters to ensure continuous coverage. Existing constellation deployments are typically optimized either for low- and mid-latitude regions or for full polar coverage, leaving high-latitude regional scenarios such as the North Atlantic insufficiently explored. This work provides insights into the key characteristics associated with the deployment of satellites in LEO for North Atlantic coverage. Therefore, we investigate how constellation inclination, minimum elevation angle, altitude, and satellite footprint jointly affect visibility probability, revisit time, path loss, and coverage continuity. Results show that the minimum elevation angle is a critical design parameter since a Walker Delta constellation with 64 satellites at 1000 km altitude can provide continu

The purpose of this article is to explore the opportunity of recent and detailed unconventional data from the tourism sector collected from « Booking.com » to make a finer and more up-to-date analysis than that established by conventional data, particularly, at the territorial level of North Africa. We extracted and geolocalised about 40 variables of different types covering 1852 accommodations on Booking.com to analyze the characteristics of territorial tourist offer of the six North African countries (10 of 12 Moroccan regions, 3 of 13 Mauritanian Wilayas, 26 of 48 Algerian Wilayas, 13 of 24 Tunisian Governorates, 1 region of Libya, 15 of 27 Egyptian Mohafazats). Then, we used a random sample of 10% of the most recent appreciations of nearly 606000 tourists of the three most dynamic destinations (Marrakech-Safi, Tunis, Cairo) by analyzing the feelings of their comments with a differentiation according origin of tourists. We concluded that the accommodation offer of the territories of North Africa is very diversified and unclassified offers are slightly better appreciated compared to those classified. The coastal regions have higher prices compared to the interior of the countries

The Moon is a primary focus of space exploration. Current navigation methods face significant limitations in providing precise location data for lunar missions. In particular, existing methods often require direct Line of Sight to Earth, have limited capacity, and suffer from long signal travel times. This paper aims to tackle these challenges through a novel single satellite navigation system at the lunar North Pole. By utilising the Doppler effect, this system facilitates 3D geolocation of a stationary receiver on the lunar surface. Key findings include choosing a Low Lunar Orbit (LLO) suitable for North Pole coverage, designing a 3-step geolocation algorithm tailored to lunar conditions, constructing a comprehensive error budget, and evaluating the system performance through Dilution of Position (DOP).

We present results of our dynamical stream modelling for the North West Stream in the outer halo of the Andromeda galaxy (M31). Comprising two main segments, the North West Stream was thought to be a single structured arching around M31. However, recent evidence suggests that it is two separate, unrelated, streams. To test this hypothesis we use observational data from 6 fields associated with the upper segment of the North West Stream together with 8 fields and 5 globular clusters associated with the lower segment to constrain model orbits. We fit both segments of the stream using a fixed potential model for M31 and an orbit integrator to compare orbits with the observed streams. We measure the central tracks and predict proper motions for for the upper segment (lower segment) finding ${μ^*_α}$ = 0.078$^{+0.015}_{-0.012}$ (0.085$^{+0.001}_{-0.002}$) mas/yr and ${μ_δ}$ = $-$0.05$^{+0.008}_{-0.009}$ ($-$0.095$^{+0.003}_{-0.005}$) mas/yr. Our results support the hypothesis that the dwarf spheroidal galaxy Andromeda XXVII is the progenitor of the upper segment of the North West Stream and that the upper and lower segments do not comprise a single structure. We propose that the upper s

South and North Korea both use the Korean language. However, Korean NLP research has focused on South Korean only, and existing NLP systems of the Korean language, such as neural machine translation (NMT) models, cannot properly handle North Korean inputs. Training a model using North Korean data is the most straightforward approach to solving this problem, but there is insufficient data to train NMT models. In this study, we create data for North Korean NMT models using a comparable corpus. First, we manually create evaluation data for automatic alignment and machine translation. Then, we investigate automatic alignment methods suitable for North Korean. Finally, we verify that a model trained by North Korean bilingual data without human annotation can significantly boost North Korean translation accuracy compared to existing South Korean models in zero-shot settings.

The North Atlantic Oscillation (NAO) is a leading mode of atmospheric variability, affecting the North Atlantic Ocean on sub-seasonal to multi-decadal timescales. The NAO changes the atmospheric forcing at the ocean's surface, including winds and surface buoyancy fluxes, both of which are known to impact large-scale gyre circulation. However, the relative role of other physical processes (such as mesoscale eddies and topography) in influencing gyre circulation under NAO variability is not fully understood. Here, we analyze a series of ocean--sea ice simulations using a barotropic vorticity budget to understand the long-term response of the North Atlantic gyre circulation to NAO forcing. We find that for each standard deviation increase in the NAO index, the subtropical and subpolar gyres intensify by 0.90 Sv and 3.41 Sv (1 Sv = 10$^6$ m$^3$ s$^{-1}$) respectively. The NAO-induced wind stress anomalies drive approximately 90\% of the change in the subtropical gyre's interior flow. However, in the subpolar gyre's interior, in addition to wind stress, flow-topography interactions, stratification (influenced by surface heat fluxes), and non-linear advection significantly influence the

Annual North Atlantic tropical cyclone (TC) counts are frequently modeled as a Poisson process with a state-dependent rate. We provide a lower bound on the forecasting error of this class of models. Remarkably we find that this bound is already saturated by a simple linear model that explains roughly 50 percent of the annual variance using three climate indices: El Niño Southern Oscillation (ENSO), average sea surface temperature (SST) in the main development region (MDR) of the North Atlantic and the North Atlantic oscillation (NAO) atmospheric circulation index (Kozar et al 2012). As expected under the bound, increased model complexity does not help: we demonstrate that allowing for quadratic and interaction terms, or using an Elastic Net to forecast TC counts using global SST maps, produces no detectable increase in skill. We provide evidence that observed TC counts are consistent with a Poisson process, limiting possible improvements in TC modeling by relaxing the Poisson assumption.

In this paper we address the issue of stability for the near-inertial Pollard waves, as a model for the halocline in the region of the Arctic Ocean centered around the North Pole, derived in Puntini (2026). Adopting the short-wavelength instability approach, the stability of such flows reduces to study the stability of a system of ODEs along fluid trajectories, leading to the result that, when the steepness of the near-inertial Pollard waves exceeds a specific threshold, those waves are linearly unstable. The explicit dispersion relation of the model allows to easily compute such threshold, knowing the physical properties of the water column.

The coupled nature of the ocean-atmosphere system frequently makes understanding the direction of causality difficult in ocean-atmosphere interactions. This study presents a method to decompose turbulent heat fluxes into a component which is directly forced by atmospheric circulation, and a residual which is assumed to be primarily `ocean-forced'. This method is applied to the North Atlantic in a 500-year pre-industrial control run using the Met Office's HadGEM3-GC3.1-MM model. The method identifies residual heat flux modes largely associated with variations in ocean circulation and shows that these force equivalent barotropic circulation anomalies in the atmosphere. The first of these modes is characterised by the ocean warming the atmosphere along the Gulf Stream and North Atlantic Current and the second by a dipole of cooling in the western subtropical North Atantic and warming in the sub-polar North Atlantic. Analysis of atmosphere-only simulations confirms that these heat flux patterns are indeed forcing the atmospheric circulation changes seen in the pre-industrial control run. It is found that the Gulf Stream plays a critical role in the atmospheric circulation response to d

Atmospheric transient eddies and low-frequency flow contribution to the ocean surface wave climate in the North Atlantic during boreal winter is investigated (1980 - 2016). We conduct a set of numerical simulations with a state-of-the-art spectral wave model Wavewatch III forced by decomposed wind fields derived from the ERA-Interim reanalysis (0.7° horizontal resolution). Synoptic-scale processes (2-10 day bandpassed winds) are found to have the largest impact on the formation of wind waves in the western mid-latitude North Atlantic along the North American and western Greenland coasts. The eastern North Atlantic is found to be influenced by the combination of low-frequency forcing (>10 day bandpassed winds) contributing up to 60% and synoptic processes contributing up to 30% to mean wave heights. Mid-latitude storm track variability is found to have a direct relationship with wave height variability on the eastern and western margins of the North Atlantic in particular implying an association between cyclone formation over the North American Eastern Seaboard and wave heights anomalies in the eastern North Atlantic. A shift in wave height regimes defined using an EOF analysis i

This study presents the inaugural analysis of income mobility in North Macedonia from 1995-2021 using the Mixing Time and Mean First Passage Time (MFPT) metrics. We document larger mobility (in terms of Mixing Time) during the '90s, with and decreasing trend (in terms of mobility) until 1999. After this year the Mixing time has been consistent with a value of around 4 years. Using the MFPT, we highlight the evolving challenges individuals face when aspiring to higher income tiers. Namely, we show that there was a noticeable upward trend in MFPT from 1995 to 2006, a subsequent decline until 2017, and then an ascent again, peaking in 2021. These findings provide a foundational perspective on the income mobility in North Macedonia.

Catch-and-effort data are among the primary sources of information for assessing the status of terrestrial wildlife and fish. In fishery science, elaborate stock-assessment models are fitted to such data in order to estimate fish-population sizes and guide management decisions. Given the importance of catch-and-effort data, we scoured a comprehensive dataset pertaining to albacore tuna (Thunnus alalunga) in the north Pacific ocean for novel ecological information content about this commercially valuable species. Specifically, we used unsupervised learning based on finite mixture modelling to reveal that the north Pacific albacore-tuna stock can be divided into four pseudo-cohorts ranging in age from approximately 3 to 12 years old. We discovered that smaller size pseudo-cohorts inhabit relatively high -- subtropical to temperate -- latitudes, with hotspots off the coast of Japan. Larger size pseudo-cohorts inhabit lower -- tropical to subtropical -- latitudes, with hotspots in the western and central north Pacific. These results offer evidence that albacore tuna prefer different habitats depending on their size and age, and point to long-term migratory routes for the species that t

Despite widespread calls for transparent artificial intelligence systems, the term is too overburdened with disparate meanings to express precise policy aims or to orient concrete lines of research. Consequently, stakeholders often talk past each other, with policymakers expressing vague demands and practitioners devising solutions that may not address the underlying concerns. Part of why this happens is that a clear ideal of AI transparency goes unsaid in this body of work. We explicitly name such a north star -- transparency that is user-centered, user-appropriate, and honest. We conduct a broad literature survey, identifying many clusters of similar conceptions of transparency, tying each back to our north star with analysis of how it furthers or hinders our ideal AI transparency goals. We conclude with a discussion on common threads across all the clusters, to provide clearer common language whereby policymakers, stakeholders, and practitioners can communicate concrete demands and deliver appropriate solutions. We hope for future work on AI transparency that further advances confident, user-beneficial goals and provides clarity to regulators and developers alike.

A key outstanding question in Martian science is 'are the polar caps gaining or losing mass and what are the implications for past, current and future climate?' To address this question, we use observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) of the north polar cap during late summer for multiple Martian years, to monitor the summertime water cycle in order to place quantitative limits on the amount of water ice deposited and sublimed in late summer. We establish here for the first time the summer cycle of water ice absorption band signatures on the north polar cap. We show that in a key region in the interior of the north polar cap, the absorption band depths grow until Ls=120, when they begin to shrink, until they are obscured at the end of summer by the north polar hood. This behavior is transferable over the entire north polar cap, where in late summer regions 'flip' from being net sublimating into net condensation mode. This transition or 'mode flip' happens earlier for regions closer to the pole, and later for regions close to the periphery of the cap. The observations and calculations presented herein estimate that on average a water ice lay

Here we describe the ultramafic talc-carbonate unit of the North Pole Dome. The North Pole Dome (NPD) is located in the centre of the East Pilbara Terrane (Van Kranendonk et al., 2007). The NPD is a structural dome of bedded, dominantly mafic volcanic rocks of the Warrawoona and Kelly Groups that dip gently away from the North Pole Monzogranite exposed in the core of the dome (Figure 1) (Van Kranendonk, 1999, 2000). Average dips vary from 30 to 60 degrees in the inner part of the dome to about 60 to 80 degrees in the outer part of the dome (Van Kranendonk, 2000). The North Pole Monzogranite is interpreted to represent a syn-volcanic laccolith to the Panorama Formation (Thorpe et al., 1992) and has been estimated to extend approximately 1.5km below the surface, based on gravity surveys (Blewett et al., 2004). Felsic volcanic formations are interbedded with the greenstones (Hickman, 1983), and these are capped by cherts that indicate hiatuses in volcanism (Barley, 1993; Van Kranendonk, 2006). An overall arc-related model for hydrothermal activity is favored by Barley (1993), whereas more recent studies have indicated a mantle-plume model for igneous and hydrothermal activity at the N

We present the characterization of a low background NaI(Tl) crystal for the SABRE North experiment. The crystal NaI-33, was studied in two different setups at Laboratori Nazionali del Gran Sasso, Italy. The Proof-of-Principle (PoP) detector was equipped with a liquid scintillator veto and collected data for about one month (90 kg$\times$days). The PoP-dry setup consisted of NaI-33 in a purely passive shielding and collected data for almost one year (891 kg$\times$days). The average background in the energy region of interest (1-6 keV) for dark matter search was 1.20 $\pm$ 0.05 and 1.39 $\pm$ 0.02 counts/day/kg/keV within the PoP and the PoP-dry setup, respectively. This result opens to a new shielding design for the physics phase of the SABRE North detector, that does not foresee the use of an organic liquid scintillator external veto.

We employ a statistical model of North Atlantic tropical cyclone (TC) tracks to investigate the relationship between sea-surface temperature (SST) and North American TC landfall rates. The track model is conditioned on summer SST in the tropical North Atlantic being in either the 19 hottest or the 19 coldest years in the period 1950-2005. For each conditioning many synthetic TCs are generated and landfall rates computed. Compared to direct analysis of historical landfall, the track model reduces the sampling error by projecting information from the entire basin onto the coast. There are 46% more TCs in hot years than cold in the model, which is highly significant compared to random sampling and corroborates well documented trends in North Atlantic TC number in recent decades. In the absence of other effects, this difference results in a significant increase in model landfall rates in hot years, uniform along the coast. Hot-cold differences in the geographic distribution of genesis and in TC propagation do not significantly alter the overall landfall-rate difference in the model, and the net landfall rate is 1/4.7 yr in hot years and 1/3.1 yr in cold years. SST influence on genesis

We use observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) of the north polar cap during late summer for two Martian years, to monitor the complete summer cycle of albedo and water ice grain size in order to place quantitative limits of the amount of water ice deposited in late summer. We establish here for the first time the complete spring to summer cycle of water ice grain sizes on the north polar cap. The apparent grain sizes grow until Ls=132, when they appear to shrink again, until they are obscured at the end of summer by the north polar hood. Under the assumption that the shrinking of grain sizes is due to the deposition of find grained ice, we quantify the amount of water ice deposited per Martian boreal summer, and estimate the amount of water ice that must be transported equatorward. Interestingly, we find that the relative amount of water ice deposited in the north cap during boreal summer (0.7-7 microns) is roughly equivalent to the average amount of water ice deposited on the south polar cap during austral summer (0.6-6 microns).

North Pacific subsurface temperature data from the Simple Ocean Data Assimilation model at 10m, 50m, 75m, 100m and 150m depths, are analyzed using a combination of state-space decomposition and subspace identification techniques to examine the spatial structure of thermal variability within the upper water column. We identify four common trends from our analysis that display the major broad-scale patterns in the North Pacific over a 47 year period (1958-2004): (1) a basin-wide near-surface warming trend that identifies the mid 1980's as a change point from a cooling to a warming trend; (2) a contrasting cooling in the central basin and warming along the coast of North America that began in the early 1970's; (3) a cooling along the transition zone and the west coast of North America that becomes dominant around 1998; (4) and contrasting differences in the subarctic and subtropical gyres displaying differences in processes at each depth. We also provide a detailed analysis of the temperature variability at four chosen locations: 52.5N 142.5W (Gulf of Alaska), 37.5N 172.5W (central basin), 37.5N 137.5W (off coast of California), and 27.5N 137.5W (off coast of Baja California) for both