Unprecedented Network Research Articles

Contrasting Future Growth of Norway Spruce and Scots Pine Forests Under Warming Climate.

Forests are essential to climate change mitigation through carbon sequestration, transpiration, and turnover. However, the quantification of climate change impacts on forest growth is uncertain and even contradictory in some regions, which is the result of spatially constrained studies. Here, we use an unprecedented network of 1.5 million tree growth records from 493 Picea abies and Pinus sylvestris stands across Europe to predict species-specific tree growth variability from 1950 to 2016 (R2 > 0.82) and develop 21st-century gridded projections considering different climate change scenarios. The approach demonstrates overall positive effects of warming temperatures leading to 25% projected conifer growth increases under the SPP370 scenario, but these additional carbon gains are spatially inhomogeneous and associated with geographic climate gradients. Maximum gains are projected for pines in Scandinavia, where growth trajectories indicate 50% increases by 2071-2100. Smaller but significant growth reductions are projected in Mediterranean Europe, where conifer growth shrinks by 25% in response to warmer temperatures. Our results reveal potential mitigating effects via forest carbon sequestration increases in response to global warming and stress the importance of effective forest management.

Exploration of complex nanostructures in block copolymers

The exploration of nanoscale morphologies with three-dimensional spatial arrangements in block copolymers involves the manipulation of compositional fluctuations at interfaces, induction of conformational asymmetry, and design of complex architectures. Despite the abundance of triply periodic minimal surfaces identified to date, the experimental demonstration of thermodynamically stable complex nanostructures with high-packing frustration remains limited. This research update focuses on the importance of molecular interactions for stabilizing complex nanostructures and proposes the use of end-group chemistry as a versatile method for realizing thermodynamically stable network structures with high-packing frustration in simple linear diblock copolymers. The proposed approach substantially alters phase diagrams and reveals unprecedented network structures in block copolymers. Ongoing research has the potential to generate even more diverse and stable nanostructures, thereby advancing nanotechnology and expanding our understanding of polymers and materials science. Published by the American Physical Society 2024

Informing Decisionmakers in Real Time

To offer evidence to policymakers during the COVID-19 pandemic, the National Academies formed an unprecedented network of social science experts who fielded questions and offered advice.

Tree species growth response to climate warming varies by forest canopy position in boreal and temperate forests.

Reports of forest sensitivity to climate change are based largely on the study of overstory trees, which contribute significantly to forest growth and wood supply. However, juveniles in the understory are also critical to predict future forest dynamics and demographics, but their sensitivity to climate remains less known. In this study, we applied boosted regression tree analysis to compare the sensitivity of understory and overstory trees for the 10 most common tree species in eastern North America using growth information from an unprecedented network of nearly 1.5 million tree records from 20,174 widely distributed, permanent sample plots across Canada and the United States. Fitted models were then used to project the near-term (2041-2070) growth for each canopy and tree species. We observed an overall positive effect of warming on tree growth for both canopies and most species, leading to an average of 7.8%-12.2% projected growth gains with climate change under RCP 4.5 and 8.5. The magnitude of these gains peaked in colder, northern areas for both canopies, while growth declines are projected for overstory trees in warmer, southern regions. Relative to overstory trees, understory tree growth was less positively affected by warming in northern regions, while displaying more positive responses in southern areas, likely driven by the buffering effect of the canopy from warming and climate extremes. Observed differences in climatic sensitivity between canopy positions underscore the importance of accounting for differential growth responses to climate between forest strata in future studies to improve ecological forecasts. Furthermore, latitudinal variation in the differential sensitivity of forest strata to climate reported here may help refine our comprehension of species range shift and changes in suitable habitat under climate change.

Mechanistic Insights into the Stepwise (4+2) Cycloaddition toward Chiral Fused Uracil Derivatives

AbstractThe mechanism of the previously reported stereoselective (4+2) cycloaddition of N‐protected 6‐methyluracil‐5‐carbaldehydes and (E)‐β‐nitrostyrenes catalyzed by Takemoto's tertiary amine/thiourea organocatalyst was explored, using density functional theory (DFT) calculations on a model representative reaction. The cyclization reaction, which afforded notable enantioenriched carbocycle‐fused uracils embedding three contiguous stereocenters, was here proven to be the result of a four‐step sequence comprising a key stereo‐defining Michael addition, followed by a completely diastereoselective intramolecular Henry reaction. Going beyond the hitherto reported activation modes, a complex and unprecedented network of hydrogen‐bonding interactions between the chiral catalyst and the reaction partners has been disclosed, in which the protonated tertiary amine and the thiourea moiety of the catalyst simultaneously activate both the electrophile and the nucleophile components. By applying the Energetic Span Model (ESM) to four competitive energetic profiles, we unveiled the most plausible reaction pathways best fitting the experimental data, with close correlation with the observed enantiomeric ratio of the product.magnified image

Stochastic modeling and performance analysis in balancing load and traffic for vehicular ad hoc networks: A review

SummaryThe rapid growth of vehicular applications has resulted in high demand for Internet technology, which demands an unprecedented network capacity and a high quality of service (QoS). In vehicular ad hoc networks (VANETs), since nodes (vehicles) are highly mobile. The dynamic nature of the network topology in the VANET system changes due to frequent changes in link connectivity. The vehicles‐to‐vehicles (V2V), vehicles‐to‐infrastructure (V2I), and QoS, as well as the heterogeneity of applications within the VANET. VANETs have been introduced to make driving comfortable by providing safety and support to drivers. Due to the flexibility and offloading schemes available in‐vehicle applications, there are some limitations. However, there are many issues in providing optimum service provisioning and scheduling in the vehicular environment. In VANETs, BSs and roadside units (RSUs) improve QoS. However, Internet services transmit packets to vehicles using stochastic models, and it predicts the traffic on a VANET. We provide open challenges to drive stochastic models in this direction.

A Single-Atom Upgrade to Polydicyclopentadiene

Chemical cross-links within polymers increase mechanical strength and rigidity. Such cross-links can be either irreversible (e.g., those derived from carbon–carbon bonds) or reversible (e.g., those that depend on X–H···O hydrogen bonds). Here we describe a ketone-functionalized derivative of polydicyclopentadiene that establishes an unprecedented network of vinyl C–H···O hydrogen bonds within the polymer. The resulting thermoset displays a significantly increased glass transition temperature relative to the unfunctionalized polymer, together with enhancements to storage modulus, Young’s modulus, and compression strength.

Warming-induced tree growth may help offset increasing disturbance across the Canadian boreal forest.

Large projected increases in forest disturbance pose a major threat to future wood fiber supply and carbon sequestration in the cold-limited, Canadian boreal forest ecosystem. Given the large sensitivity of tree growth to temperature, warming-induced increases in forest productivity have the potential to reduce these threats, but research efforts to date have yielded contradictory results attributed to limited data availability, methodological biases, and regional variability in forest dynamics. Here, we apply a machine learning algorithm to an unprecedented network of over 1 million tree growth records (1958 to 2018) from 20,089 permanent sample plots distributed across both Canada and the United States, spanning a 16.5 °C climatic gradient. Fitted models were then used to project the near-term (2050 s time period) growth of the six most abundant tree species in the Canadian boreal forest. Our results reveal a large, positive effect of increasing thermal energy on tree growth for most of the target species, leading to 20.5 to 22.7% projected gains in growth with climate change under RCP 4.5 and 8.5. The magnitude of these gains, which peak in the colder and wetter regions of the boreal forest, suggests that warming-induced growth increases should no longer be considered marginal but may in fact significantly offset some of the negative impacts of projected increases in drought and wildfire on wood supply and carbon sequestration and have major implications on ecological forecasts and the global economy.

Toward a Heterogeneous Smart Electromagnetic Environment for Millimeter-Wave Communications: An Industrial Viewpoint

Fifth generation (5G) and beyond communication systems open the door to millimeter Wave (mmWave) frequency bands to leverage the extremely large operating bandwidths and deliver unprecedented network capacity. These frequency bands are affected by high propagation losses that severely limit the achievable coverage. The simplest way to address this problem would be to increase the number of installed mmWave base stations (BSs), at the same time augmenting the overall network cost, power consumption and ElectroMagnetic Field (EMF) levels. As alternative direction, here we propose to complement the macro-layer of mmWave BSs with a heterogeneous deployment of Smart Electromagnetic (Smart EM) Entities - namely IAB nodes, Smart Repeaters, Reconfigurable Intelligent Surfaces (RISs) and passive surfaces - that is judiciously planned to minimize the total installation costs while at the same time optimizing the network spectral efficiency. Initial network planning results underline the effectiveness of the proposed approach. The available technologies and the key research directions for achieving this view are thoroughly discussed by accounting for issues ranging from system-level design to the development of new materials.

A dataset of temperature, humidity, and liquid water path retrievals from a network of ground-based microwave radiometers dedicated to fog investigation

The database presented in this study has been acquired during the SOuth west FOGs 3D (SOFOG3D) experiment for processes study. This international campaign led by Météo-France during the winter 2019–2020 aimed at deploying a unique network of both in situ and remote sensing measurements in order to document spatial and temporal variabilities of fog events. To support this scientific objective but also to conduct first data assimilation experiments within the French convective scale model AROME, an un-precedented network of 8 ground-based microwave radiometers (MWR) has been deployed in 7 different locations known to be prone to fog occurrences. The database gives access to vertical profiles of temperature and humidity (both absolute and relative) from the surface up to 10 km altitude as well as integrated water vapor and liquid water path estimates. The retrieved profiles offer a very large database that can be exploited for several scientific purposes: fog process studies at specific location, documentation on the variability of fog properties at the regional scale, better understanding of the atmospheric boundary layer (ABL) height and dynamics during wintertime conditions, development of nowcasting products dedicated to fog alerts, data assimilation experiments to improve fog forecasts, development of synergetical advanced products, and evaluation of new model configurations with advanced parameterization or resolutions.

Conductive Stimuli-Responsive Coordination Network Linked with Bismuth for Chemiresistive Gas Sensing.

This paper describes the design, synthesis, characterization, and performance of a novel semiconductive crystalline coordination network, synthesized using 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) ligands interconnected with bismuth ions, toward chemiresistive gas sensing. Bi(HHTP) exhibits two distinct structures upon hydration and dehydration of the pores within the network, Bi(HHTP)-α and Bi(HHTP)-β, respectively, both with unprecedented network topology (2,3-c and 3,4,4,5-c nodal net stoichiometry, respectively) and unique corrugated coordination geometries of HHTP molecules held together by bismuth ions, as revealed by a crystal structure resolved via microelectron diffraction (MicroED) (1.00 Å resolution). Good electrical conductivity (5.3 × 10–3 S·cm–1) promotes the utility of this material in the chemical sensing of gases (NH3 and NO) and volatile organic compounds (VOCs: acetone, ethanol, methanol, and isopropanol). The chemiresistive sensing of NO and NH3 using Bi(HHTP) exhibits limits of detection 0.15 and 0.29 parts per million (ppm), respectively, at low driving voltages (0.1–1.0 V) and operation at room temperature. This material is also capable of exhibiting unique and distinct responses to VOCs at ppm concentrations. Spectroscopic assessment via X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopic methods (i.e., attenuated total reflectance-infrared spectroscopy (ATR-IR) and diffuse reflectance infrared Fourier transformed spectroscopy (DRIFTS)), suggests that the sensing mechanisms of Bi(HHTP) to VOCs, NO, and NH3 comprise a complex combination of steric, electronic, and protic properties of the targeted analytes.

A Series of Mesoporous Rare‐Earth Metal–Organic Frameworks Constructed from Organic Secondary Building Units

AbstractFurther development of metal–organic frameworks (MOFs) requires an establishment of hierarchical interaction within the framework. Herein, we report a series of mesoporous rare‐earth (RE) MOFs that are constructed from an unusual 12‐connected π‐stacked pyrene secondary building unit (SBU) and a typical 12‐connected RE6 cluster (RE=Eu, Y, Yb, Tb, Ce). The judicious design of a butterfly‐shape pyrene ligand with a tert‐butyl substituent enables the formation of the disordered 12‐connected organic SBUs on its strong intermolecular π–π interactions. The assembly of 12‐connected inorganic cuboctahedron SBUs and 12‐connected organic distorted hexagonal prism SBUs generates an unprecedented network that can be further simplified into a 4,4‐connected pts net linked from planar square and tetrahedra. This work provides fresh insights into the design and synthesis of frameworks constructed from coordinatively, covalently, and noncovalently linked building units.

A Series of Mesoporous Rare-Earth Metal-Organic Frameworks Constructed from Organic Secondary Building Units.

Further development of metal-organic frameworks (MOFs) requires an establishment of hierarchical interaction within the framework. Herein, we report a series of mesoporous rare-earth (RE) MOFs that are constructed from an unusual 12-connected π-stacked pyrene secondary building unit (SBU) and a typical 12-connected RE6 cluster (RE=Eu, Y, Yb, Tb, Ce). The judicious design of a butterfly-shape pyrene ligand with a tert-butyl substituent enables the formation of the disordered 12-connected organic SBUs on its strong intermolecular π-π interactions. The assembly of 12-connected inorganic cuboctahedron SBUs and 12-connected organic distorted hexagonal prism SBUs generates an unprecedented network that can be further simplified into a 4,4-connected pts net linked from planar square and tetrahedra. This work provides fresh insights into the design and synthesis of frameworks constructed from coordinatively, covalently, and noncovalently linked building units.

Recruitment Disruption and the Role of Unaffected Populations for Potential Recovery After the Pinna nobilis Mass Mortality Event

A devastating mass mortality event (MME) very likely caused by the protozoan Haplosporidium pinnae first detected in 2016 in the Western Mediterranean Sea, is pushing the endemic bivalve Pinna nobilis to near extinction. Populations recovery, if possible, will rely on larval dispersal from unaffected sites and potential recolonization through recruitment of resistant juveniles. To assess the impact of the MME on the species’ larval recruitment, an unprecedented network of larval collector stations was implemented over several thousands of kilometers along the Western Mediterranean coasts during the three years after the onset of the MME. The findings of this network showed a generalized disruption in recruitment with dramatic consequences for the recovery of the species. However, there were exceptions to this pattern and recruits were recorded in a few sites where the resident population had been decimated. This hints to the importance of unaffected populations as larval exporting sources and the role of oceanographic currents in larval transport in the area, representing a beacon of hope in the current extremely worrying scenario for this emblematic species.

2119-P: Deep Profiling of Phosphorylation Dynamics in Human Islets in Response to Inflammatory Cytokines

Human islets, particularly beta cells, are sensitive to their environment and face many types of stressors. These stressors may stem from intense demand for hormone production, viral insult, impaired intra-islet signaling, immune activation, or a combination of any/all of the previously mentioned stressors. How islets respond to these stressors is vital to the continued function and whole-body cooperation of these important cells, especially in patients which are already carry predisposed risk. It is well understood that once immune invasion occurs, islets face a veritable barrage of cytokine/chemokine chemical stressors. Elucidating the early cellular response to these stressors is paramount to understanding the complex interconnected balance at play between the immune system and the islet. The initial response is critical and must occur quickly; this is why we chose to look at changes in phosphorylation-based dynamics which occur at these short time scales. Islet samples from 10 donor patients were harvested and cytokine treated ex vivo and subsequently collected over a time course of 10 min, 30 min and 2 hours. Samples were then prepared for mass-spectrometry-based proteomics analysis using the newly-developed BASIL (Boosting to Amplify Signal using Isobaric Labeling) method for small-scale enriched phosphoproteomics. This technique allowed for unprecedented deep phosphoproteome coverage and signaling network reconstruction of cytokine-induced stressed human islets; thereby allowing us to observe a molecular-level response to this kind of stress in this critical phase of disease pathogenesis. Disclosure A.C. Swensen: None. Y. Ye: None. E. Dirice: None. R. Kulkarni: None. W. Qian: None. Funding National Institutes of Health (UC4DK104167, R01DK122160)

‘What he hath gather'd together shall not be lost’: remembering James Petiver

James Petiver FRS ( ca 1663–1718) was a professional apothecary and prominent natural historian in London at the turn of the eighteenth century. This essay introduces a special issue of Notes and Records , ‘Remembering James Petiver’, marking the 300th anniversary of his death. Combining his known biography with new research, it accounts for Petiver's formation as urban apothecary and botanist, his emergence as public natural historian in the mid 1690s, and his subsequent career as natural history collector and author. Petiver's museum of plants and invertebrates was accumulated by co-ordinating an unprecedented network of relatively ordinary people, many of them medical practitioners, to collect for him wherever they travelled: North and South America, western and southern Africa, mainland Europe, South and East Asia, Indonesia and the Philippines. This network and its achievements were predicated upon Britain's expanding global commercial and colonial interests (including those that exploited the traffic in and labour of enslaved human beings). It also depended upon Petiver's strategic management of his collaborators, through the exchange of correspondence and material objects. New analysis of Petiver's network, specimens, publications and manuscripts revises the prevailing view that he was careless and disorganized, to reveal a socially industrious and intellectually discriminating natural scientist.

Detecting new generations of threats using attribute‐based attack graphs

In recent years, the increase in cyber threats has raised many concerns about security and privacy in the digital world. However, new attack methods are often limited to a few core techniques. Here, in order to detect new threat patterns, the authors use an attack graph structure to model unprecedented network traffic. This graph for the unknown attack is matched to a pre-known threat database, which contains attack graphs related to each known threat. The main challenge is to associate unknown traffics to a family of known threats. For this, the authors utilise random walks and pattern theorem. The authors utilise the pattern theorem and apply it to a set of proposed algorithms for detecting new generations of malicious traffics. Under the assumption of having a proper threat database, the authors argue that for each unknown threat, which belongs to a family of threats, it is possible to find at least one matching pattern with high matching rate and sensitivity.

New Methods for Collaborative Experiential Learning to Provide Personalised Formative Assessment

Abstract—¬Supporting diverse and rapidly changing learning styles of new digital age generations is one of the major hurdles to higher education in the age of massification of education markets. Higher education institutions must now utilize unprecedented network speed and mobile technology to create stimulating learning environments for new digital age generations. This paper presents a new learning and teaching model that combines dynamic learning space (DLS) and mobile collaborative experimental learning (MCEL) for supporting diverse learning styles of students. DLS assists students with state-of-art modern wireless network technologies in order to support fast-paced, multi-tasking, data and content intensive collaborative learning in class. The model further extends student learning activities beyond classroom by allowing students to continue their learning anywhere and anytime conveniently using their mobile devices. MCEL provides automated continuous personalized formative-feedback 24/7. The main objectives of the model are to improve student engagement and to provide ownership of their learning journey, experiential learning, contextualized learning, and formative assessment at low cost. The model employs three factors that influence collaborative experiential learning and formative assessment. The three factors are: (1) the use of learning space within the classroom, (2) wireless learning technology, and (3) mobile learning system (m-Learning). Pilot studies of the model are conducted and evaluated on two groups of postgraduate students. Their participation is observed, and a survey is conducted. The results show that (1) DLS encourages high-level learning and diverse learning styles to move away from passive low-level knowledge intensive learning activities; (2) MCEL supports Bigg's constructive alignment in curriculum design, contextualized experimental learning, and personalized formative learning.

Enhancing RAN Throughput by Optimized CoMP Controller Placement in Optical Metro Networks

The fifth generation (5G) of mobile communications will target unprecedented network performance and quality of service for end users. Among the various aspects which will be addressed in 5G, advanced cell coordination is deemed as crucial to maximize network throughput. In particular, in this paper, we refer to coordinated multipoint (CoMP) techniques that allow coordinating groups of cells (i.e., clusters) through a coordination controller, namely, a radio controller coordinator (RCC), to enhance the mobile network throughput by reducing interference. We focus on the placement of RCCs in the metro optical network and on its impact on the performance of cell coordination. We provide strategies to perform an optimized placement of such controllers in metro optical networks in order to maximize network throughput via cell coordination. Several CoMP techniques have been designed, whose throughput gain is affected by various factors, e.g., gain increases with the cluster size, while it decreases for larger latencies between the RCC and cells. As current metro networks are characterized by a hierarchical architecture with different levels of central offices, the choice of where to place controllers to maximize throughput gain can be optimized according to several factors, i.e., network geographical dimension, cells density, and available technology. In addition, selection of the most appropriate CoMP technique to be used in each cluster is not trivial, as the gain provided by the various techniques is differently affected by cluster size and latency between the RCC and cells. Our results show that under certain conditions optimized placement provides up to around 10% higher coordination gain with respect to fixed controller placement. Moreover, when adopting fronthaul technology, the coordination gain provided by an optimized controller placement may increase up to 20% in comparison to fixed placement.

Open-Source Network Optimization Software in the Open SDN/NFV Transport Ecosystem

Transport ecosystems that combine software defined networking (SDN) and network function virtualization (NFV) are characterized by an unprecedented network control and resource dynamicity. Manual optimization is unmanageable. In this context, open systems that manage and orchestrate SDN/NFV-enabled networks offer programming frameworks that abstract the low-level particularities in the data-plane forwarding devices and in the hardware appliances that provide the IT resources. Although these open systems present notable complexity, their programming abstractions promote a client layer where third-party applications can provide different functionalities thus enabling optimization-as-a-service business opportunities. In this paper, we cover open-source optimization software initiatives for offline planning and online provisioning and orchestration of SDN/NFV networks. With this goal in mind, we first focus on open software (and framework) initiatives through a set of realistic use cases that require optimization in multi-layer optical transport scenarios and ecosystems that combine transport with IT resources. The importance of a joint optimization of both network and IT domains is emphasized, a new paradigm triggered by SDN/NFV technologies. We discuss the theoretical limits to algorithm performances, and review available open-source frameworks for problem modeling that enable the interaction with solvers. Finally, we focus on the Net2Plan open-source network planning tool, a Java-based software that suitably embraces the multiple features required in the optimization of joint transport network and IT resource SDN/NFV ecosystems. Recent works based on Net2Plan are reviewed to illustrate its suitability for rapid algorithm prototyping, and for interaction with SDN/NFV-enabled networks.