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

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

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

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

High efficiency somatic embryogenesis and plant germination in grapevine cultivars Chardonnay and Brachetto a grappolo lungo

A highly efficient, reproducible method for somatic embryogenesis induction, plant recovery and embryogenic culture preservation has been developed for cvs Chardonnay and Brachetto a grappolo lungo (Vitis vinifera), starting from immature anthers and ovaries. Embryogenic induction efficiency was 2 % and 17 % in anthers for Chardonnay and Brachetto g.l., respectively, and 14 % in ovaries for both cultivars. Embryogenic cultures of both genotypes are still propagating 3.5 years after the initial induction and are still morphogenic. Embryo conversion into plantlets occurred at suitable efficiencies during a 100 d culture for both Chardonnay (37 % and 15 %) and Brachetto g.l. (30 % and 29 %), in the two media tested. Organogenesis was also obtained from cotyledonary leaves of Chardonnay.

Radio and millimeter properties of z∼5.7z \sim 5.7 Lyα\alpha emitters in the COSMOS field: limits on radio AGN, submm galaxies, and dust obscuration

We present observations at 1.4 and 250 GHz of the $z\sim 5.7$ Ly$\alpha$ emitters (LAE) in the COSMOS field found by Murayama et al.. At 1.4 GHz there are 99 LAEs in the lower noise regions of the radio field. We do not detect any individual source down to 3$\sigma$ limits of $\sim 30\mu$Jy beam$^{-1}$ at 1.4 GHz, nor do we detect a source in a stacking analysis, to a 2$\sigma$ limit of $2.5\mu$Jy beam$^{-1}$. At 250 GHz we do not detect any of the 10 LAEs that are located within the central regions of the COSMOS field covered by MAMBO ($20' \times 20'$) to a typical 2$\sigma$ limit of $S_{250} < 2$mJy. The radio data imply that there are no low luminosity radio AGN with $L_{1.4} > 6\times 10^{24}$ W Hz$^{-1}$ in the LAE sample. The radio and millimeter observations also rule out any highly obscured, extreme starbursts in the sample, ie. any galaxies with massive star formation rates $> 1500$ M$_\odot$ year$^{-1}$ in the full sample (based on the radio data), or 500 M$_\odot$ year$^{-1}$ for the 10% of the LAE sample that fall in the central MAMBO field. The stacking analysis implies an upper limit to the mean massive star formation rate of $\sim 100$ M$_\odot$ year$^{-1}$.Comment: 11 pages AAStex format 3 figures. ApJ COSMOS Special Issue. Changes: Added 'Note added in proof' to reflect nine new sources in the LAE sampl