Delay-induced rebounds in CO_{2} emissions and critical time-scales to meet global warming targets

While climate science debates are focused on the attainment of peak anthropogenic CO2 emissions and policy tools to reduce peak temperatures, the human‐energy‐climate system can hold “rebound” surprises beyond this peak. Following the second industrial revolution, global per capita CO_{2} emissions (c_{c}) experienced a punctuated growth of about 100% every 60 years, mainly attributable to technological development and its global spread. A model of the human‐energy‐climate system capable of reproducing past punctuated dynamics shows that rebounds in global CO_{2} emissions emerge due to delays intrinsic to the diffusion of innovations. Such intrinsic delays in the adoption and spread of low‐carbon emitting technologies, together with projected population growth, upset the warming target set by the Paris Agreement. To avoid rebounds and their negative climate effects, model calculations show that the diffusion of climate‐friendly technologies must occur with lags one‐order of magnitude shorter (i.e., ∼6 years) than the characteristic timescale of past punctuated growth in c_{c}. Radically new strategies to globally implement the technological advances at unprecedented rates are needed if the current emission goals are to be achieved

Seasonal hysteresis of surface urban heat islands

Temporal dynamics of urban warming have been extensively studied at the diurnal scale, but the impact of background climate on the observed seasonality of surface urban heat islands (SUHIs) remains largely unexplored. On seasonal time scales, the intensity of urban–rural surface temperature differences (ΔTs) exhibits distinctive hysteretic cycles whose shape and looping direction vary across climatic zones. These observations highlight possible delays underlying the dynamics of the coupled urban–biosphere system. However, a general argument explaining the observed hysteretic patterns remains elusive. A coarse-grained model of SUHI coupled with a stochastic soil water balance is developed to demonstrate that the time lags between radiation forcing, air temperature, and rainfall generate a rate-dependent hysteresis, explaining the observed seasonal variations of ΔTs. If solar radiation is in phase with water availability, summer conditions cause strong SUHI intensities due to high rural evaporative cooling. Conversely, cities in seasonally dry regions where evapotranspiration is out of phase with radiation show a summertime oasis effect controlled by background climate and vegetation properties. These seasonal patterns of warming and cooling have significant implications for heat mitigation strategies as urban green spaces can reduce ΔTs during summertime, while potentially negative effects of albedo management during winter are mitigated by the seasonality of solar radiation

Global convergence of COVID-19 basic reproduction number and estimation from early-time SIR dynamics

The SIR ('susceptible-infectious-recovered') formulation is used to uncover the generic spread mechanisms observed by COVID-19 dynamics globally, especially in the early phases of infectious spread. During this early period, potential controls were not effectively put in place or enforced in many countries. Hence, the early phases of COVID-19 spread in countries where controls were weak offer a unique perspective on the ensemble-behavior of COVID-19 basic reproduction number Ro inferred from SIR formulation. The work here shows that there is global convergence (i.e., across many nations) to an uncontrolled Ro = 4.5 that describes the early time spread of COVID-19. This value is in agreement with independent estimates from other sources reviewed here and adds to the growing consensus that the early estimate of Ro = 2.2 adopted by the World Health Organization is low. A reconciliation between power-law and exponential growth predictions is also featured within the confines of the SIR formulation. The effects of testing ramp-up and the role of 'super-spreaders' on the inference of Ro are analyzed using idealized scenarios. Implications for evaluating potential control strategies from this uncontrolled Ro are briefly discussed in the context of the maximum possible infected fraction of the population (needed to assess health care capacity) and mortality (especially in the USA given diverging projections). Model results indicate that if intervention measures still result in Ro > 2.7 within 44 days after first infection, intervention is unlikely to be effective in general for COVID-19

An ecohydrological journey of 4500 years reveals a stable but threatened precipitation–groundwater recharge relation around Jerusalem

Groundwater is a key water resource in semiarid and seasonally dry regions around the world, which is replenished by intermittent precipitation events and mediated by vegetation, soil, and regolith properties. Here, a climate reconstruction of 4500 years for the Jerusalem region was used to determine the relation between climate, vegetation, and groundwater recharge. Despite changes in air temperature and vegetation characteristics, simulated recharge remained linearly related to precipitation over the entire analyzed period, with drier decades having lower rates of recharge for a given annual precipitation due to soil memory effects. We show that in recent decades, the lack of changes in the precipitation–groundwater recharge relation results from the compensating responses of vegetation to increasing CO2, i.e., increased leaf area and reduced stomatal conductance. This multicentury relation is expected to be modified by climate change, with changes up to −20% in recharge for unchanged precipitation, potentially jeopardizing water resource availability

The Binding Pocket at the Interface of Multimeric Telomere G-quadruplexes: Myth or Reality?

Human telomeric DNA with hundreds of repeats of the 5’-TTAGGG-3’ motif plays a crucial role in several biological processes. It folds into G-quadruplex (G4) structures and features a pocket at the interface of two contiguous G4 blocks. Up to now no structural NMR and crystallographic data are available for ligands interacting with contiguous G4s. Naphthalene diimide monomers and dyads were investigated as ligands of a dimeric G4 of human telomeric DNA comparing the results with those of the model monomeric G4. Time-resolved fluorescence, circular dichroism, isothermal titration calorimetry and molecular modeling were used to elucidate binding features. Ligand fluorescence lifetime and induced circular dichroism unveiled occupancy of the binding site at the interface. Thermodynamic parameters confirmed the hypothesis as they remarkably change for the dyad complexes of the monomeric and dimeric telomeric G4. The bi-functional ligand structure of the dyads is a fundamental requisite for binding at the G4 interface as only the dyads engage in complexes with 1 : 1 stoichiometry, lodging in the pocket at the interface and establishing multiple interactions with the DNA skeleton. In the absence of NMR and crystallographic data, our study affords important proofs of binding at the interface pocket and clues on the role played by the ligand structure

Nitrate affects transcriptional regulation of UPBEAT1 and ROS localisation in roots of Zea mays L.

Nitrogen is an indispensable nutrient for crops but its availability in agricultural soils is subject to considerable fluctuation. Plants have developed plastic responses to external N fluctuations in order to optimise their development. The coordinated action of nitric oxide and auxin seems to allow the cells of the transition zone (TZ) of the root apex of N-deprived maize to rapidly sense nitrate. Preliminary results support the hypothesis that reactive oxygen species (ROS) signalling might also have a role in this pathway, probably through a putative maize orthologue of UPBEAT1 (UPB1). To expand on this hypothesis and better understand the different roles played by different root portions, we investigated the dynamics of ROS production, and the molecular and biochemical regulation of the main components of ROS production and scavenging in tissues of the Meristem, Transition Zone, Elongation Zone and Maturation Zone of maize roots. The results suggest that the inverse regulation of ZmUPB1 and ZmPRX112 transcription observed in cells of the TZ in response to nitrogen depletion or nitrate supply affects the balance between H2O2 and O2 12 in the root apex and consequently triggers differential root growth. This explanation is supported by additional results on the overall metabolic and transcriptional regulation of ROS homeostasis

A bicarotid trunk in association with an aberrant right subclavian artery. Report of two cases, clinical impact, and review of the literature

A combination of an aberrant right subclavian artery (ARSA) and a bicarotid trunk (BCT) appears in up to 2.5% of the population. The aim of this study is to report the higher total and male incidence of this variation in the literature and to summarise its clinical impact, providing useful knowledge to anatomists, radiologists, cardiologists, and vascular and thoracic surgeons in order to avoid diagnostic pitfalls and therapeutic complications. A total of 72 (43 female and 29 male) Greek Caucasian formalin-embalmed cadavers were studied. The international literature was reviewed along with the dissection archives of the Department of Anatomy from 1986 to 2009. Two male cadavers were found to have an ARSA combined with a BCT (incidence: total 2.78%, males 6.9%, females 0%). Both aortic arches consisted of three branches: (1) the BCT, (2) the left subclavian artery, and (3) the ARSA. The common carotids followed a normal route to the neck; the ARSA passed between the trachea and the oesophagus in the first case and behind the oesophagus in the second case, and was accompanied by a non-recurrent laryngeal nerve. In the second cadaver the ARSA formed a sharp angle (kinking/buckling) on its route to the right arm. The ARSA is associated with several congenital cardiovascular anomalies and some chromosomal and other syndromes. It is occasionaly responsible for causing dysphagia, dyspnoea, or acute ischaemia to the right upper limb, and it may present as a superior mediastinal mass in cases of aneurysm formation. (Folia Morphol 2011; 70, 2: 68–73

Matching ecohydrological processes and scales of banded vegetation patterns in semi-arid catchments

While the claim that water-carbon interactions result in spatially coherent vegetation patterning is rarely disputed in many arid and semi-arid regions, the significance of the detailed water pathways and other high frequency variability remain an open question. How the short temporal scale meteorological fluctuations form the long term spatial variability of available soil water in complex terrains due to the various hydrological, land surface and vegetation dynamic feedbacks, frames the scope of the work here. Knowledge of the detailed mechanistic feedbacks between soil, plants and the atmosphere will lead to advances in our understanding of plant water availability in arid and semi-arid ecosystems and will provide insights for future model development concerning vegetation pattern formation. In this study, quantitative estimates of water fluxes and vegetation productivity are provided for a semi-arid ecosystem with established vegetation bands on hillslopes using numerical simulations. A state-of-the-science process based ecohydrological model is used, which resolves hydrological and plant physiological processes at the relevant space and time scales, for relatively small periods (e.g. decades) of mature ecosystems (i.e. spatially static vegetation distribution). To unfold the mechanisms that shape the spatial distribution of soil moisture, plant productivity and the relevant surface/subsurface and atmospheric water fluxes, idealized hillslope numerical experiments are constructed, where the effects of soil-type, slope steepness and overland flow accumulation area are quantified. Those mechanisms are also simulated in the presence of complex topography features on landscapes. The main results are: (a) Short temporal scale meteorological variability and accurate representation of the scales at which each ecohydrological process operates are crucial for the estimation of the spatial variability of soil water availability to the plant root zone; (b) Water fluxes such as evapotranspiration, infiltration, runoff-runon and subsurface soil water movement have a dynamic short temporal scale behavior that determines the long term spatial organization of plant soil water availability in ecosystems with established vegetation patterns; (c) Hypotheses concerning the hydrological responses that can lead to vegetation pattern formation have to accommodate realistic and physically based representations of the fast dynamics of key ecohydrological fluxes