Symmetries of the Energy-Momentum Tensor: Some Basic Facts

It has been pointed by Hall et al. [1] that matter collinations can be defined by using three different methods. But there arises the question of whether one studies matter collineations by using the ${\cal L}_\xi T_{ab}=0$, or ${\cal L}_\xi T^{ab}=0$ or ${\cal L}_\xi T_a^b=0$. These alternative conditions are, of course, not generally equivalent. This problem has been explored by applying these three definitions to general static spherically symmetric spacetimes. We compare the results with each definition.Comment: 17 pages, accepted for publication in "Communications in Theoretical Physics

Study of strange quark density fluctuations in Au+Au Collisions at sNN\sqrt{s_{NN}} = 7.7-200 GeV from AMPT Model

The strangeness production is an important observable to study the QCD phase diagram. The yield ratios of strange quark can be helpful to search for the QCD critical point and/or first order phase transition. In this work, we studied the production of $K^{\pm}$, $\Xi^-(\bar{\Xi}^{+})$, $\phi$ and $\Lambda (\bar \Lambda)$ in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, 54.4, 62.4 and 200 GeV from A Multi-Phase Transport model with string melting version (AMPT-SM). We calculated the invariant yield of these strange hadrons using a different set of parameters reported in earlier studies and also by varying the hadronic cascade time ($t_{max}$) in the AMPT-SM model. We also calculated the yield ratios, $\mathcal{O}_{K^{\pm}-\Xi^{-}(\bar \Xi^{+})-\phi-\Lambda (\bar \Lambda)}$ which are sensitive to the strange quark density fluctuations and found that the AMPT-SM model fails to describe the non-monotonic trend observed by the STAR experiment. The negative particle ratio are found to be higher than the ratio of positive particles which is consistent with the experimental data. A significant effect is also seen on these ratios by varying the $t_{max}$. This study based on the transport model can be helpful to provide possible constraints as well as reference for the search of CEP in future heavy-ion experiments. Our findings suggest that the ongoing Beam Energy Scan program at RHIC and the future heavy-ion experiments will be able to find/locate the possible CEP in the QCD phase diagram which results large quark density fluctuations.Comment: 7 pages, 2 figure

Healthy-home approach: lasting changes in hygiene behaviour in rural Bangladesh

NGOs have been struggling for over a decade in Bangladesh to bring visible changes in hygiene behaviour at the community level. However, few of these initiatives focus specifically on promoting hygiene behaviour at the practice level. Providing hygiene messages following traditional approaches achieves numeric figures, but often fails to bring real changes on the ground. WaterAid Bangladesh piloted an approach called “healthy home” under its rural programme, which encourages communities to promote safe water and sanitation through recognition and owners of “healthy home”. A wide range of stakeholders engage in the process led by local government institutions (LGIs).. Over an eight months period of time, more than 80% household owners have been awarded as healthy-home promoters against targeted numbers, and have been declared so by LGIs publicly. Recognition, dignity and ownership work as motivating factors in this process, which could be capitalised for greater achievement in other programmes

A Passivity-Preserving Frequency-Weighted Model Order Reduction Technique

© 2004-2012 IEEE. Frequency-weighted model order reduction techniques aim to yield a reduced order model whose output matches that of the original system in the emphasized frequency region. However, passivity of the original system is only known to be preserved in the single-sided weighted case. A frequency-weighted model order reduction technique is proposed, which guarantees the passive reduced models in the double-sided weighted case. A set of easily computable error bound expressions are also presented

Effect of hadronic cascade time on freeze-out properties of Identified Hadrons in Au+Au Collisions at sNN\sqrt{s_{NN}} = 7.7-39 GeV from AMPT Model

We report the transverse momentum $p_T$ spectra of identified hadrons ($\pi^\pm$, $K^\pm$ and $p(\bar p)$) in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7 - 39 GeV from A Multi Phase Transport Model with string melting effect (AMPT-SM). During this study, a new set of parameters are explored to study the effect of hadronic cascade by varying hadronic cascade time $t_{max}$ = 30 $f$m/$c$ and 0.4 $f$m/$c$. No significant effect of this change is observed in the $p_T$ spectra of light hadrons and the AMPT-SM model reasonably reproduces the experimental data. To investigate the kinetic freeze-out properties the blast wave fit is performed to the $p_T$ spectra and it is found that the blast wave model describes the AMPT-SM simulations well. We additionally observe that the kinetic freeze-out temperature ($T_{kin}$) increases from central to peripheral collisions, which is consistent with the argument of short-lived fireball in peripheral collisions. Whereas the transverse flow velocity, shows a decreasing trend from central to peripheral collisions indicating a more rapid expansion in the central collisions. Both, $T_{kin}$ and show a weak dependence on the collision energy at most energies. We also observe a strong anti-correlation between $T_{kin}$ and $$. The extracted freeze-out parameters from the AMPT-SM simulations agree with the experimental data as opposed to earlier studies that reported some discrepancies. Whereas, no significant effect is found on the freeze-out parameters by varying the $t_{max}$. We also report the $p_T$ spectra of light hadrons and their freeze-out parameters by AMPT-SM simulations at $\sqrt{s_{NN}}$ = 14.5 GeV, where no experimental data is available for comparison. Overall, the set of parameters used in this study well describes the experimental data at BES energies.Comment: 12 pages, 7 figures, 2 table

Study of Baryon number transport using model simulations in pppp collisions at LHC Energies

We report on the excitation function of anti-baryon to baryon ratios ($\overline{p}/p$, {\alam /\lam} and {\axi / \xim}) in $pp$ collisions at {\sqrts} = 0.9, 2.76, 7 TeV from DPMJET-III, Pythia~8, EPOS~1.99, and EPOS-LHC model simulations. To study the predictions of these models at {\sqrts} = 13.6 TeV. The anti-baryon to baryon ratios are extremely important for the study of baryon number transport mechanisms. These ratios help determine the carriers of the baryon number and in the extraction of baryon structure information. Even though all models show a good agreement between model simulations and data, the ratios extracted from DPMJET-III model closely describes data at all energies. It is observed that these ratios converge to unity for various model predictions. This convergence also indicates that the anti-baryon to baryon ratios follow the mass hierarchy, such that the hyperon specie containing more strange quarks ({\alam /\lam} and {\axi / \xim}) approaches unity faster than specie containing fewer strange quarks ($\overline{p}/p$). It is also observed that the $\overline{B}/B$ ratio approaches unity more rapidly with the increase in {\sqrts} energy. At lower energies we observe an excess production of baryons over anti-baryons. However, this effect vanishes at higher energies due to the baryon-anti-baryon pair production and the baryon-anti-baryon yield becomes equal. Using model simulations, we additionally compute the asymmetry, (A\equiv\frac{N_{p}-N_{\bar{p}}}N_{p}+N_{\bar{p}}}) for protons. The asymmetry shows a decreasing trend with increase in energy from 0.9 to 7 TeV for all energies. This asymmetry trend is confirmed by model predictions at {\sqrts} = 13.6 TeV which will help to put possible constraints on model calculations at {\sqrts} = 13.6 TeV once the Run-III data for LHC becomes available.Comment: 14 pages, 8 figures, 2 table

ASSESSMENT OF FARMERS’ KNOWLEDGE REGARDING CHILD LABOR IN AGRICULTURE: A CASE STUDY OF COTTON GROWERS IN DISTRICT BAHAWALPUR

The work which affects the education, dignity and health of a child is known as child labor. It exists in agriculture sector of Pakistan mostly in the form of hazardous work. The main objective of the study was to investigate the degree of knowledge of cotton growers on child labor issue with special reference to Decent Work of International Labor Organization (ILO). The study was conducted in Bahawalpur district where Decent Work has been implemented by World Wide Fund for Nature (WWF)-Pakistan since 2013 as a part of its Sustainable Agriculture Program. Three categories of farmers were identified among a total of 388 selected cotton growers i.e. Farmers having high level of awareness, farmers having basic level of awareness and farmers having no awareness of child labor. Farmers were also categorized into three groups on the basis of their land holding i.e. (Category ‘a’) 1-7 acres, (b) >7-20 acres and (c) >20-50 acres. The data was analyzed through descriptive statistical method. Among category ‘a’ 7.5%, 88.7% and 3.7% of the farmers had advance, basic and no awareness, respectively. Among category ‘b’ 7.2%, 88.5% and4.2% farmers had advance, basic and no awareness, respectively. Among category ‘c’ 5.8%, 90.2% and 3.9% farmers had advance, basic and no awareness, respectively. Since there was a large proportion of those farmers who have only basic level of awareness on child labor among all the three land holding categories, therefore, there is a need to educate farmers on preventing child labor at their farms to promote sustainable cotton

Novitates Gabonenses 93: a fresh look at Podostemaceae in Gabon following recent inventories, with a new combination for Ledermanniella nicolasii

Background and aims – Podostemaceae is a family of strictly aquatic plants found in rapids and waterfalls. Despite a recent treatment in the Flore du Gabon, the family remained poorly known, with no major studies including Gabonese collections, and almost no targeted inventories since 1966. We present the first large-scale inventory of this family in Gabon, targeting Podostemaceae throughout the country, providing new additions to the flora of Gabon and many new records of poorly known species. Material and methods – Fieldwork was conducted in Gabon between 2017 and 2021. The collected specimens were primarily preserved in ethanol with associated silica gel-preserved material and photographs. Material available at BR, BRLU, LBV, MO, P, WAG, and Z/ZT was examined. For each species, information on distribution and ecology is presented, as well as a distribution map in Gabon. Key results – The 500 newly collected specimens represent 91.4% of all known collections of Podostemaceae from Gabon. Three taxa are newly recorded for the country, including one genus (Inversodicraea tenax, Ledermanniella schlechteri, and Saxicolella nana). New distribution records are also presented for 13 little-known species. Four taxa are excluded from the Gabonese flora (the genus Dicraeanthus, Inversodicraea ledermannii, Ledermanniella sanagaensis, and Macropodiella garrettii). To date, 20 species belonging to five different genera are known to occur in Gabon. A new combination is proposed for Ledermanniella nicolasii, and Inversodicraea tanzaniensis is now considered as a synonym of Inversodicraea tenax