Let's talk about varying G

It is possible that fundamental constants may not be constant at all. There is a generally accepted view that one can only talk about variations of dimensionless quantities, such as the fine structure constant $\alpha_{\rm e}\equiv e^2/4\pi\epsilon_0\hbar c$. However, constraints on the strength of gravity tend to focus on G itself, which is problematic. We stress that G needs to be multiplied by the square of a mass, and hence, for example, one should be constraining $\alpha_{\rm g}\equiv G m_{\rm p}^2/\hbar c$, where $m_{\rm p}$ is the proton mass. Failure to focus on such dimensionless quantities makes it difficult to interpret the physical dependence of constraints on the variation of G in many published studies. A thought experiment involving talking to observers in another universe about the values of physical constants may be useful for distinguishing what is genuinely measurable from what is merely part of our particular system of units.Comment: 6 pages, Gravity Research Foundation essa

Effect of Nano Silicon and Plant Growth-Promoting Rhizobacteria on Biomass, Nodulation and Some Physiological Traits of Grasspea (Lathyrus sativus L.)

IntroductionGrasspea (Lathyrus sativus L.) is one of the most important forage crops in the world. It contains 12 to 20% protein. Silicon (Si) existing in the Earth’s crust is classified as the most abundant element after oxygen. Although silicon is not considered an essential element for plant growth, but a number of studies have reported that it as an important factor in plants that plays an important role in the resistance mechanisms of plants against environmental stress. Also, it plays a crucial physiological role in photosynthetic rate and chlorophyll content. One of the most effective factors in increasing the Grasspea biomass is seed inoculation with plant growth-promoting rhizobacteria (PGPR). Some of the benefits provided by PGPR are the ability to produce gibberellic acid, cytokinins and ethylene, N2 fixation, solubilization of mineral phosphates and other nutrients. Numerous studies have shown a substantial increase in dry matter accumulation via inoculation with PGPR. Some researchers reported that seed inoculation with PGPR enhanced relative water content and photochemical efficiency of PSII lathyrus under water limitations. Therefore, the aim of this study was to evaluate the effects of nano silicon and seed inoculation with plant growth-promoting rhizobacteria on biomass, nodulation and some physiological traits of Grasspea. Materials and MethodsIn order to study the effect of nano silicon and plant growth-promoting rhizobacteria on biomass, nodulation and some physiological traits of Grasspea, a factorial experiment was conducted based on randomized complete block design with three replications in research farm of University of Mohaghegh Ardabili in 2021. Treatment were included application of plant growth-promoting rhizobacteria at four levels (no inoculation as control, seed inoculation with Azosprillum lipoferum strain OF, Psedomonas putida strain 186, both application of Azospirillium and Pseudomonas) and nano silicon foliar application at four levels (foliar application with water as control, foliar application 25, 50 and 75 mg.L-1 nano silicon). The area is located at 38° 15ʹ N latitude and 48° 20ʹ E longitude with an elevation of 1350 m above mean sea level. Climatically, the area is situated in the wet zone with cool winter and hot summer. For inoculation, seeds were coated with gum Arabic as an adhesive and rolled into the suspension of bacteria until uniformly coated. Seeds were inoculated with plant growth promoting rhizobacteria (PGPR) at the rate of approximately 1 × 107 colony forming units (CFU) mg-1 just before planting. Foliar application of nano silicon was conducted in two stages of vegetative growth. Nano silicon powder added to deionized water and was placed on ultra sonic equipment (100 W and 40 kHz) on a shaker for better solution. At the Flowering stage, the leaves of plants were selected to measure the stem and leaf protein, chlorophyll index, RWC (relative water content), quantum yield, stomatal conductance and EC (electrical conductivity). RWC was calculated based on method of Kostopoulou et al. (2010). Chlorophyll Index was calculated by chlorophyll meter (SPAD-502; Konica Minolta Sensing, Inc., Japan). The Quantum yield of leaves was calculated with fluorometer (chlorophyll fluorometer; Optic Science-OS-30 USA). Stomata conductance was measured with a porometer system (Porometer AP4, Delta-T Devices Ltd., Cambridge, UK) according to the instructions in its manual. Leaf electrical conductivity (EC) values were measured at room temperature of 23±1°C using an electrical-conductivity meter. Analysis of variance and mean comparisons were performed using SAS 9.1 computer software packages. The main effects and interactions were tested using the least significant difference (LSD) test at the 0.05 probability level.Results and DiscussionThe results showed that both application of Azospirillium and Pseudomonas and foliar application of 75 mg.L-1 nano silicon increased root weight and volume (40.4 and 41.9%), number of active nodules (81.2%), percentage of active nodules (33.2%), nodule dry weight (37.4%), chlorophyll index (46%), relative water content (46.3%), stomatal conductance (34.6%) and quantum yield (34.1%) in comparison with no application of PGPR and nano silicon. Also, the highest leaf and stem protein (23.37 and 12.66%) and total biomass (37.7 %) were obtained in both application of Azospirillium and Pseudomonas and foliar application of 75 mg.L-1 nano silicon in comparison with no application of PGPR and nano silicon. ConclusionIt seems that application of PGPR and foliar application of nano silicon can increase biomass of Lathyrus sativus due to nodulation and  improving  physiological traits

The decrease in NKG2D+ Natural Killer cells in peripheral blood of patients with metastatic colorectal cancer

Background: Natural killer (NK) cells play important roles in the immune defense against tumors such as colorectal cancer. In humans, NKG2D is an activating immune receptor constitutively expressed in most cytotoxic lymphocytes including NK and CD8+ T cells. In this study, the expression of NKG2D molecule was investigated in peripheral blood NK cells from colorectal cancer patients and compared with healthy subjects. Methods: We studied 21 non-metastatic (low-grade), 17 non-metastatic (high-grade), 16 metastatic colorectal cancer patients, and 24 healthy controls. Peripheral blood samples were obtained to isolate peripheral blood mononuclear cells (PBMCs) and the percentage of peripheral blood NKG2D+CD3-CD56+ NK cells was analyzed by flow cytometry. The expression of NKG2D at mRNA level was also measured by real-time PCR in both, patients and control subjects. Results: The results showed a significant reduction in the percentage of NKG2D+NK cells as well as NKG2D mRNA expression in peripheral blood of metastatic colon cancer patients. Conclusion: This result suggests that decreased expression of activating NKG2D receptor in metastatic colorectal cancer might compromise NK cell function and allow tumor to evade immunity (Tab. 3, Fig. 4, Ref. 33). Text in PDF www.elis.sk

Modulation of Sn concentration in ZnO nanorod array: intensification on the conductivity and humidity sensing properties

Tin (Sn)-doped zinc oxide (ZnO) nanorod arrays (TZO) were synthesized onto aluminum-doped ZnO-coated glass substrate via a facile sonicated sol–gel immersion method for humidity sensor applications. These nanorod arrays were grown at different Sn concentrations ranging from 0.6 to 3 at.%. X-ray diffraction patterns showed that the deposited TZO arrays exhibited a wurtzite structure. The stress/strain condition of the ZnO film metamorphosed from tensile strain/compressive stress to compressive strain/tensile stress when the Sn concentrations increased. Results indicated that 1 at.% Sn doping of TZO, which has the lowest tensile stress of 0.14 GPa, generated the highest conductivity of 1.31 S cm− 1. In addition, 1 at.% Sn doping of TZO possessed superior sensitivity to a humidity of 3.36. These results revealed that the optimum performance of a humidity-sensing device can be obtained mainly by controlling the amount of extrinsic element in a ZnO film

Dimensionless cosmology

Although it is well known that any consideration of the variations of fundamental constants should be restricted to their dimensionless combinations, the literature on variations of the gravitational constant $G$ is entirely dimensionful. To illustrate applications of this to cosmology, we explicitly give a dimensionless version of the parameters of the standard cosmological model, and describe the physics of Big Bang Neucleosynthesis and recombination in a dimensionless manner. The issue that appears to have been missed in many studies is that in cosmology the strength of gravity is bound up in the cosmological equations, and the epoch at which we live is a crucial part of the model. We argue that it is useful to consider the hypothetical situation of communicating with another civilization (with entirely different units), comparing only dimensionless constants, in order to decide if we live in a Universe governed by precisely the same physical laws. In this thought experiment, we would also have to compare epochs, which can be defined by giving the value of any {\it one} of the evolving cosmological parameters. By setting things up carefully in this way one can avoid inconsistent results when considering variable constants, caused by effectively fixing more than one parameter today. We show examples of this effect by considering microwave background anisotropies, being careful to maintain dimensionlessness throughout. We present Fisher matrix calculations to estimate how well the fine structure constants for electromagnetism and gravity can be determined with future microwave background experiments. We highlight how one can be misled by simply adding $G$ to the usual cosmological parameter set

Search for an invisible Z′Z^\prime in a final state with two muons and missing energy at Belle II

The $L_{\mu}-L_{\tau}$ extension of the standard model predicts the existence of a lepton-flavor-universality-violating $Z^{\prime}$ boson that couples only to the heavier lepton families. We search for such a $Z^\prime$ through its invisible decay in the process $e^+ e^- \to \mu^+ \mu^- Z^{\prime}$. We use a sample of electron-positron collisions at a center-of-mass energy of 10.58GeV collected by the Belle II experiment in 2019-2020, corresponding to an integrated luminosity of 79.7fb$^{-1}$. We find no excess over the expected standard-model background. We set 90$\%$-confidence-level upper limits on the cross section for this process as well as on the coupling of the model, which ranges from $3 \times 10^{-3}$ at low $Z^{\prime}$ masses to 1 at $Z^{\prime}$ masses of 8$GeV/c^{2}$

Measurement of the Λc+\Lambda_c^+ lifetime

An absolute measurement of the $\Lambda^{+}_c$ lifetime is reported using $\Lambda_c^+\rightarrow pK^-\pi^+$ decays in events reconstructed from data collected by the Belle II experiment at the SuperKEKB asymmetric-energy electron-positron collider. The total integrated luminosity of the data sample, which was collected at center-of-mass energies at or near the $\Upsilon(4S)$ resonance, is 207.2~\mbox{fb}^{-1}. The result, $\tau(\Lambda^{+}_c) = 203.20 \pm 0.89 \,\mathrm{(stat)} \pm 0.77 \,\mathrm{(syst)}$ fs, is the most precise measurement to date and is consistent with previous determinations.Comment: Accepted for publication in PR

Measurement of the branching fraction and CP\it CP asymmetry of B0→π0π0B^{0} \rightarrow \pi^{0} \pi^{0} decays using 198×106198 \times 10^6 BB‾B\overline{B} pairs in Belle II data

We report measurements of the branching fraction and $\it CP$ asymmetry in $B^{0} \to \pi^{0} \pi^{0}$ decays reconstructed at Belle II in an electron-positron collision sample containing $198 \times 10^{6}$ $B\overline{B}$ pairs. We measure a branching fraction \mathcal{B}(\Bpipi) = (1.38 \pm 0.27 \pm 0.22) \times 10^{-6} and a $\it CP$ asymmetry \Acp(\Bpipi) = 0.14 \pm 0.46 \pm 0.07, where the first uncertainty is statistical and the second is systematic

Search for a τ+τ−\tau^+\tau^- resonance in e+e−→μ+μ−τ+τ−e^{+}e^{-}\rightarrow \mu^{+}\mu^{-} \tau^+\tau^- events with the Belle II experiment

We report the first search for a non-standard-model resonance decaying into $\tau$ pairs in $e^{+}e^{-}\rightarrow \mu^{+}\mu^{-} \tau^+\tau^-$ events in the 3.6-10 GeV/$c^{2}$ mass range. We use a 62.8 fb$^{-1}$ sample of $e^+e^-$ collisions collected at a center-of-mass energy of 10.58 GeV by the Belle II experiment at the SuperKEKB collider. The analysis probes three different models predicting a spin-1 particle coupling only to the heavier lepton families, a Higgs-like spin-0 particle that couples preferentially to charged leptons (leptophilic scalar), and an axion-like particle, respectively. We observe no evidence for a signal and set exclusion limits at 90% confidence level on the product of cross section and branching fraction into $\tau$ pairs, ranging from 0.7 fb to 24 fb, and on the couplings of these processes. We obtain world-leading constraints on the couplings for the leptophilic scalar model for masses above 6.5 GeV/$c^2$ and for the axion-like particle model over the entire mass range