Determination of the Newtonian Gravitational Constant Using Atom Interferometry

We present a new measurement of the Newtonian gravitational constant G based on cold atom interferometry. Freely falling samples of laser-cooled rubidium atoms are used in a gravity gradiometer to probe the field generated by nearby source masses. In addition to its potential sensitivity, this method is intriguing as gravity is explored by a quantum system. We report a value of G=6.667 10^{-11} m^{3} kg^{-1} s^{-2}, estimating a statistical uncertainty of $\pm$ 0.011 10^{-11} m^{3} kg^{-1} s^{-2} and a systematic uncertainty of $\pm$ 0.003 10^{-11} m^{3} kg^{-1} s^{-2}. The long-term stability of the instrument and the signal-to-noise ratio demonstrated here open interesting perspectives for pushing the measurement accuracy below the 100 ppm level.Comment: 4 figure

Trajectories in the Context of the Quantum Newton's Law

In this paper, we apply the one dimensional quantum law of motion, that we recently formulated in the context of the trajectory representation of quantum mechanics, to the constant potential, the linear potential and the harmonic oscillator. In the classically allowed regions, we show that to each classical trajectory there is a family of quantum trajectories which all pass through some points constituting nodes and belonging to the classical trajectory. We also discuss the generalization to any potential and give a new definition for de Broglie's wavelength in such a way as to link it with the length separating adjacent nodes. In particular, we show how quantum trajectories have as a limit when $\hbar \to 0$ the classical ones. In the classically forbidden regions, the nodal structure of the trajectories is lost and the particle velocity rapidly diverges.Comment: 17 pages, LateX, 6 eps figures, minor modifications, Title changed, to appear in Physica Script

Thermodynamics of Dyonic Lifshitz Black Holes

Black holes with asymptotic anisotropic scaling are conjectured to be gravity duals of condensed matter system close to quantum critical points with non-trivial dynamical exponent z at finite temperature. A holographic renormalization procedure is presented that allows thermodynamic potentials to be defined for objects with both electric and magnetic charge in such a way that standard thermodynamic relations hold. Black holes in asymptotic Lifshitz spacetimes can exhibit paramagnetic behavior at low temperature limit for certain values of the critical exponent z, whereas the behavior of AdS black holes is always diamagnetic.Comment: 26 pages, 4 figure

How to finance energy renovation of residential buildings: Review of current and emerging financing instruments in the EU

The Paris Agreement goals require net-zero CO2 emissions by mid-century. The European Commission in its recent proposal for climate and energy strategy for 2050 indicated the need for more intensified actions to substantially improve the energy performances of buildings. With the rate of new construction in Europe, the challenge is to increase both the pace and depth of building energy renovations. Several barriers inhibit the wide uptake of comprehensive energy renovations, including the inability or inertia to finance upfront costs of energy renovations. Despite various policies implemented to address some of these barriers, current investments in buildings remain at suboptimal levels. The paper reviews current financing practices for energy renovations and investigates some innovative instruments with a special focus on their applicability to residential buildings. In addition to “traditional” financial schemes such as subsidies, tax incentives, and loans, the paper assesses innovative financing schemes: On property tax and on-bill financing, energy efficiency mortgages, and energy efficiency feed-in tariffs. The paper also investigates the concept of one-stop shops for building renovations and crowdfunding. The paper offers an assessment of the characteristics, benefits, and challenges of each analyzed financing instrument and provides policy recommendations for their successful implementation. In general, as financing instruments involve different stakeholders and due to complex nature of the sector, there is no single solution to accelerate energy renovation investment in buildings. The emerging financial models offer the potential to address the long-standing barriers to investment in energy efficiency. This article is categorized under: Energy Efficiency > Economics and Policy Energy Efficiency > Climate and Environment Energy and Climate > Economics and Policy

Thermal Behavior of Monocrystalline Silicon Solar Cells: A Numerical and Experimental Investigation on the Module Encapsulation Materials

This research outlines the numerical predictions of the heat distribution in solar cells, accompanied by their empirical validation. Finite element thermal models of five laminated silicon solar photovoltaic cells were firstly established using a simulation software (ANSYS®). The flexible laminated solar cells under study are made of a highly transparent frontsheet, a silicon cell between two encapsulants, and a backsheet. Different combinations of layers (i.e., materials and thicknesses) were taken into account in order to analyze their effect on thermal behavior. Thermal properties of materials were derived in accordance with the literature. Similarly, boundary conditions, loads, and heat losses by reflection and convection were also specified. The solar cells were tested using solar lamps under standard conditions (irradiance: 1000W/m2; room-temperature: 25°C) with real-time temperatures measured by a thermal imager. This analysis offers an interpretation of how temperature evolves through the solar cell and, consequently, how the design choice can influence the cells' efficiency

Thermal patterns in a proglacial pond create Windows of Opportunity for periphyton growth (Cevedale glacier, Italy)

In high mountain areas, deglaciation is the most evident effect of anthropogenic climatic changes. Glacier retreat is inducing worldwide an increase of both number and size of proglacial lakes and ponds, i.e., lentic water bodies located in the proglacial area and directly linked to the glacier activity: the depressions carved in the land surface allow meltwater impoundment and accumulation of glacier sediment. Over the past decades, glacier-fed lakes have become an increasingly represented ecosystem in the Alpine landscape. However, their ecological characteristics are only partially known. Glacial runoff determines cascade effects in glacier-fed standing waters. It influences both water temperature, by delivering cold meltwater to the system, and water transparency, because of the high amount of inorganic suspended solids (so called “glacial flour”) that determine high water turbidity. Therefore, proglacial lakes are highly selective habitats, where planktonic communities are quantitatively scarce and taxonomically simplified. On the other hand, given the low input of allochthonous organic matter from bare proglacial forefields, benthic primary producers (periphyton) are the major autochthonous carbon source sustaining food webs in glacially fed water bodies. Studies on glacial streams show that periphyton growth is concentrated in “Windows of Opportunity” (WOs), mainly occurring in periods of reduced glacial runoff, i.e., autumn. In the euphotic zone along the littoral area of proglacial lakes, local conditions can allow algal growth (e.g., cyanobacteria), and the abrasive impact of glacial flour is low due to scarce water turbulence. Furthermore, in lentic proglacial ecosystems, periphyton ecological niches appear to be influenced also by water thermal stratification dynamics. Previous studies observed different mixing patterns in proglacial and clear mountain lakes (i.e., without glacial influence); high-altitude ponds (surface area < 2 ha) are expected to show even different patterns of response to physical environmental setting. To better understand the link between thermal dynamics and ecology of proglacial lentic systems, we investigated temperature dynamics in the water column of a proglacial pond located in the Eastern Italian Alps (South Tyrol, Italy) and compared them with density and taxonomic composition of PPNW 2024. Universitat de Girona (Spain) benthic diatom communities, which are key components of littoral periphyton in lakes and are useful bioindicators of environmental changes. Diatoms are eukaryotic photosynthetic microalgae, characterised by a cell wall composed of silica (frustule), whose morphological characteristics are used for taxonomical identification. Specific aims of the study were: (i) to characterise the temperature dynamics in a shallow proglacial pond; (ii) to investigate how thermal dynamics can influence the presence of WOs for periphyton growth. The proglacial pond is located at 2850 m a.s.l. in the Martell valley (Stelvio National Park, CE Italian Alps). It is moraine-dammed and originated from the retreat of the Cevedale glacier about 10 years ago. Its surface area is about 4270.5 m2 with a maximum depth of around 3 m. In the ice-free seasons 2022 and 2023, we installed water level sensors and performed water discharge measurements at the pond outlet with the salt dilution method, to build a flow rating curve and estimate outlet and inlet discharge time series. In summer 2023, we installed two buoys, one in the upstream part of the pond and one in the downstream part. Each buoy was equipped with 5 temperature sensors, located at 0, 0.2, 0.4, 0.8, 1.6 m depth, recording water temperature at 5-minute intervals. We applied the CE-QUAL-W2 model, a 2-D hydrodynamic laterally averaged model, to reconstruct the temperature time series in the water column for both ice-free seasons 2022 and 2023. We calibrated the parameters of the model based on field buoy data. Meteorological data and discharge time series were used as boundary conditions for the model. We developed a simplified numerical model to estimate the inflow water temperature (i.e., glacial runoff running on debriscovered ice) as a function of air temperature and solar radiation. Preliminary results show good agreement between the observed and modelled temperature data (RMSE < 1.5°C). During the Alpine glacial summer, we observed periods of pronounced daily thermal stratification. In these periods, shallow layers showed daily fluctuations, while deeper layers were colder. Total mixing and cooling of the water column followed intense precipitation events, with lower air temperature and solar radiation. In 2022 and 2023, we analysed the benthic diatom communities collected from a known area of colonised substrata (stones covered by a layer of consolidated sediment). In the laboratory, we eliminated the organic matter in the samples by chemical oxidation, to allow the morphological observation of diatom frustules. We equalised the sample volumes at 6 ml and added an aliquot (1 ml) of solution containing a known concentration of divinylbenzene microspheres, which served as reference to compare diatom densities in the different samples. Permanent diatom mounts were prepared, and diatom frustules and microspheres were counted under the optical microscopy. Diatom communities in the Cevedale proglacial pond reached higher density values (1-43 and 2.8-404.9 × 103 N valves/cm2, respectively) than in glacier-fed streams investigated in the same geographical area (Vulcano 2020, unpublished data). Moreover, we observed a density peak in August 2022 (404.9 × 103 N valves/cm2), and not in autumn as expected. In all samples, the community was numerically dominated by the pioneer species Achnanthidium minutissimum s.l. The observed diatom density patterns suggest that periphyton PPNW 2024. Universitat de Girona (Spain) growth in the proglacial pond can be sustained also in periods of high glacial runoff. Accordingly, the model results suggest the presence of additional temperature-driven WOs for periphyton growth during the Alpine summer, with respect to the ones described in glacier-fed streams. The presence and temporal extension of the WOs in the proglacial pond depend on meteorological conditions, as thermal gradients form during dry and warm periods. In a climate change perspective, this implies that colonisation processes in the periphyton of newly formed proglacial ponds may be accelerated by prolonged periods of drought, high air temperatures and increased glacial runoff. Consequently, the natural ecological evolution of proglacial ponds may be accelerated by global warming

Could the periodontal therapy improve the cardiologic patient health? A narrative review

Background: Cardiovascular diseases (CVD) is the major cause of mortality globally, with increasing evidence suggesting a link between periodontitis, and CVD. This study aims to explore the association between periodontitis and CVD, and the impact of periodontal therapy on cardiovascular health. Methods: This review synthesized findings from preclinical and clinical studies, without publication year restrictions, examining periodontitis and CVD through various lenses. Scientific databases were inspected with keywords related to periodontitis and CVD. Results: The review identifies a substantial association between periodontitis and an increased risk of several CVD, supported by both epidemiological and interventional studies. Results suggest the complexity of the relationship, influenced by factors like the severity of periodontitis and the presence of other systemic conditions. Clinical data indicates that periodontal therapy, particularly non -surgical periodontal therapy, may reduce systemic inflammatory markers and thus may play a role in the primary and secondary prevention of CVD events, highlighting the potential of periodontal therapy to not only maintain oral health but also to modulate cardiovascular risk factors. Conclusions: Current evidence supports a significant association between periodontitis and increased cardiovascular risk, promoting integrated healthcare approaches that consider oral health as a key -component of cardiovascular care and wellbeing

Double Scaling Limits and Twisted Non-Critical Superstrings

We consider double-scaling limits of multicut solutions of certain one matrix models that are related to Calabi-Yau singularities of type A and the respective topological B model via the Dijkgraaf-Vafa correspondence. These double-scaling limits naturally lead to a bosonic string with c $\leq$ 1. We argue that this non-critical string is given by the topologically twisted non-critical superstring background which provides the dual description of the double-scaled little string theory at the Calabi-Yau singularity. The algorithms developed recently to solve a generic multicut matrix model by means of the loop equations allow to show that the scaling of the higher genus terms in the matrix model free energy matches the expected behaviour in the topological B-model. This result applies to a generic matrix model singularity and the relative double-scaling limit. We use these techniques to explicitly evaluate the free energy at genus one and genus two.Comment: 32 pages, 3 figure

Learning can be detrimental for a parasitic wasp

Animals have evolved the capacity to learn, and the conventional view is that learning allows individuals to improve foraging decisions. The parasitoid Telenomus podisi has been shown to parasitize eggs of the exotic stink bug Halyomorpha halys at the same rate as eggs of its coevolved host, Podisus maculiventris, but the parasitoid cannot complete its development in the exotic species. We hypothesized that T. podisi learns to exploit cues from this noncoevolved species, thereby increasing unsuccessful parasitism rates. We conducted bioassays to compare the responses of naïve vs. experienced parasitoids on chemical footprints left by one of the two host species. Both naïve and experienced females showed a higher response to footprints of P. maculiventris than of H. halys. Furthermore, parasitoids that gained an experience on H. halys significantly increased their residence time within the arena and the frequency of re-encounter with the area contaminated by chemical cues. Hence, our study describes detrimental learning where a parasitoid learns to associate chemical cues from an unsuitable host, potentially re-enforcing a reproductive cul-de-sac (evolutionary trap). Maladaptive learning in the T. podisi-H. halys association could have consequences for population dynamics of sympatric native and exotic host species