Addressing the missing matter problem in galaxies through a new fundamental gravitational radius

We demonstrate that the existence of a Noether symmetry in $f(R)$ theories of gravity gives rise to a further gravitational radius, besides the standard Schwarzschild one, determining the dynamics at galactic scales. By this feature, it is possible to explain the baryonic Tully-Fisher relation and the rotation curve of gas-rich galaxies without the dark matter hypothesis.Comment: 9 pages, 2 figures, to be published in JCA

Recovering the fundamental plane of galaxies by f(R)f(R) gravity

The fundamental plane (FP) of galaxies can be recovered in the framework of $f(R)$ gravity avoiding the issues related to dark matter to fit the observations. In particular, the power-law version $f(R)\propto R^n$, resulting from the existence of Noether symmetries for $f(R)$, is sufficient to implement the approach. In fact, relations between the FP parameters and the corrected Newtonian potential, coming from $R^n$, can be found and justified from a physical point of view. Specifically, we analyze the velocity distribution of elliptical galaxies and obtain that $r_c$, the scale-length depending on the gravitational system properties, is proportional to $r_e$, the galaxy effective radius. This fact points out that the gravitational corrections induced by $f(R)$ can lead photometry and dynamics of the system. Furthermore, the main byproduct of such an approach is that gravity could work in different ways depending on the scales of self-gravitating systems.Comment: 18 pages, 3 tables, 8 figures. Accepted for publication in Phys. Dark Univers

Constraining Extended Gravity Models by S2 star orbits around the Galactic Centre

We investigate the possibility to explain theoretically the observed deviations of S2 star orbit around the Galactic Centre using gravitational potentials derived from modified gravity models in absence of dark matter. To this aim, an analytic fourth-order theory of gravity, non-minimally coupled with a massive scalar field is considered. Specifically, the interaction term is given by analytic functions $f(R)$ and $f(R,\phi)$ where $R$ is the Ricci scalar and $\phi$ is a scalar field whose meaning can be related to further gravitational degrees of freedom. We simulate the orbit of S2 star around the Galactic Centre in $f(R)$ (Yukawa-like) and $f(R,\phi)$ (Sanders-like) gravity potentials and compare it with NTT/VLT observations. Our simulations result in strong constraints on the range of gravity interaction. In the case of analytic functions $f(R)$, we are not able to obtain reliable constraints on the derivative constants $f_1$ and $f_2$, because the current observations of S2 star indicated that they may be highly mutually correlated. In the case of analytic functions $f(R,\phi)$, we are able to obtain reliable constraints on the derivative constants $f_0$, $f_R$, $f_{RR}$, $f_{\phi}$, $f_{\phi\phi}$ and $f_{\phi R}$. The approach we are proposing seems to be sufficiently reliable to constrain the modified gravity models from stellar orbits around Galactic Centre.Comment: 9 pages, 6 figure to appear in Phys. Rev.

Masses of constituent quarks confined in open bottom hadrons

We apply color-spin and flavor-spin quark-quark interactions to the meson and baryon constituent quarks, and calculate constituent quark masses, as well as the coupling constants of these interactions. The main goal of this paper was to determine constituent quark masses from light and open bottom hadron masses, using the fitting method we have developed and clustering of hadron groups. We use color-spin Fermi-Breit (FB) and flavor-spin Glozman-Riska (GR) hyperfine interaction (HFI) to determine constituent quark masses (especially $b$ quark mass). Another aim was to discern between the FB and GR HFI because our previous findings had indicated that both interactions were satisfactory. Our improved fitting procedure of constituent quark masses showed that on average color-spin (Fermi-Breit) hyperfine interaction yields better fits. The method also shows the way how the constituent quark masses and the strength of the interaction constants appear in different hadron environments.Comment: 15 pages, 6 tables, 1 figure. Accepted for publication in Mod. Phys. Lett.

Constraining Non-local Gravity by S2 star orbits

Non-local theories of gravity have recently gained a lot of interest because they can suitably represent the behavior of gravitational interaction in the ultraviolet regime. Furthermore, at infrared scales, they give rise to notable cosmological effects which could be important to describe the dark energy behavior. In particular, exponential forms of the distortion function seem particularly useful for this purpose. Using Noether Symmetries, it can be shown that the only non-trivial form of the distortion function is the exponential one, which is working not only for cosmological mini-superspaces, but also in a spherically symmetric spacetime. Taking this result into account, we study the weak field approximation of this type of non-local gravity, and comparing with the orbits of S2 stars around the Galactic center (NTT/VLT data), we set constraints on the parameters of the theory. Non-local effects do not play a significant role on the orbits of S2 stars around Sgr A*, but give richer phenomenology at cosmological scales than the $\Lambda$CDM model. Also, we show that non-local gravity model gives better agreement between theory and astronomical observations than Keplerian orbits.Comment: 11 pages, 6 figures. Accepted for publication in Phys. Rev.

Electrochemical Reduction of Trinitrotoluene on a Modified Platinum Electrode

Poster presented at the 61st Annual Meeting of the International Society of Electrochemistry, Nice, France, September 26 – October 1, 201

On Orbits for a Particular Case of Axial Symmetry

A particular case of steady state and axial symmetry - the potentialformula proposed by Miyamoto and Nagai - is studied. A number of orbits of abound test particle is determined numerically, with both, the potentialparameters and initial conditions, varied. Unlike special cases, such asnearly circular and nearly planar orbits, in the case of "truly spatial orbits" the time dependence of the coordinates becomes very complicated and amathematical treatment including any known periodic functions is hardlypossible. Bearing in mind that orbits studied in the present paper aredetermined by three elements, the authors propose the mean values over time ofthe squares of velocity components to characterize them

Flora of the city of Podgorica, Montenegro: Taxonomic analysis

In this paper we present the taxonomic segment of a floristic study undertaken in the city of Podgorica in the period of 2002-2007. The check-list of spontaneously growing vascular plants includes 1227 species and subspecies belonging to 545 genera and 118 families. The dominant families are Poaceae (11.7%), asteraceae (11.2%) and Fabaceae (9.2%). The most abundant genera are Trifolium (2.1%), Euphorbia (1.5%), Carex (1.5%), Bromus (1.3%) and Vicia (1.2%). Analysis of the flora of Podgorica in comparison with some other european cities showed that the flora of Podgorica is most similar to that of Rome (Q/S= 0,7)

Flora of the city of Podgorica, Montenegro: Chorologic structure and comparison with the floras of Rome, Patras, and Salonika

Research on the geographical structure of the flora of Podgorica revealed that 85.9% of the species are native, while 14.1% are non-native. This ratio is typical of Mediterranean settlements, where even the most urbanized region reflects the overall character of the surrounding flora. In terms of chorologic groups, the three largest are: eury-Mediterranean (18.2%), cosmopolitan (12.6%), and steno-Mediterranean (8.3%). The percentage of endemic and subendemic plants is also significant (6.8%). Within the group of aliens, species of Asian origin prevail. Comparative analysis of the chorologic spectra of Podgorica, Rome, Patras, and Salonika revealed some similarities

Motorne funkcije i kognicija kod starih osoba

The prolonging of a lifespan and the increasing proportion of elderly people in general population are setting new healthcare tasks. One of them is researching and clarifying the relations and links between motoric and cognitive functions in elderly. 'Impoverishment' of cognitive capacities occurs during the aging process. Many studies show a strong link between cognition and the function of walking. There is growing evidence that the decline in cognitive functions is resulting in deterioration of walking. Usually described as characteristic of the later stages of dementia, the distortion of ambulation may also be present in the earlier stages, even before the prodromal stage of mild cognitive impairment. Speed and temporal and spatial variability of steps are the main gait characteristics which are connected to the degree of decline in cognitive processes. Those characteristics are motor phenotype that reflects the deterioration of cognitive performance and which can be used for prediction of dementia. It is assumed that physical activity provides beneficial effects at cognitive and psychological levels, including prevention and improvement of depressive states and anxiety disorders, enhancing stress reduction, improved self-confidence and above all it delays cognitive decline in the elderly. Disruption of axons and myelin in the cerebral white matter is considered one of the primary mechanisms underlying age-related cognitive decline. Therefore, maintaining white matter structural connectivity in the old age may be one of the key factors in preserving brain function and high cognitive performance necessary for independent living. Physical activity also influences cerebrovascular mechanisms, such as preserving higher blood vessel elasticity and wall integrity. Moreover, there is an association between light physical activity and white matter integrity especially in the temporal lobe. The conclusion of some studies shows a relationship between the ε4 allele and brain derived neurotrophic factor (BDNF) response to physiologic adaptation which likely impacts the extent of neuroprotective benefit gained from engagement in physical exercise. Some authors propose a program of exercises which consist of a combined aerobic and resistance training. Motoric function and cognition are closely related and using regular physical activity is important for maintaining physical and mental health in the elderly.Produžetak životnog veka i povećanje udela starijih ljudi u opštoj populaciji postavlja nove zadatke za zdravstvene službe. Jedan od njih je istraživanje i razjašnjavanje odnosa i povezanosti između motoričkih i kognitivnih funkcija kod osoba starijeg životnog doba. Tokom procesa starenja odigrava se 'osiromašenje' kognitivnih kapaciteta. Mnoge studije ukazuju na postojanje izrazite povezanosti između kognitivnih funkcija i funkcije hoda. Postoji sve više dokaza da opadanje kognitivnih funkcija rezultuje deterioracijom funkcije hoda. Poremećaj funkcije hoda se obično povezuje sa kasnijim stadijumima demencije, međutim, ona može biti narušena i u ranijim stadijumima pa čak i pre nastanka prodromalnog stadijuma tj. blagog kognitivnog poremećaja. Brzina koraka i vremenska i prostorna varijabilnost koraka su glavne karakteristike koje se povezuju sa stepenom pada kognitivnih procesa. Ove karakteristike su motorni fenotip koji reflektuje stepen deterioracije kognitivnog funkcionisanja i koji može biti upotrebljen kao prediktivni pokazatelj nastanka demencija. Pretpostavlja se da fizička aktivnost obezbeđuje pozitivne efekte na kognitivnom i psihološkom planu, uključujući prevenciju i poboljšanje depresivnih i anksioznih stanja, da redukuje stres, unapređuje samopouzdanje i konačno, odlaže nastanak procesa opadanja kognitivnih funkcija kod osoba starijeg doba. Prekidi aksonskih puteva i mijelina u beloj masi se smatraju jednim od primarnih mehanizama za nastanak opadanja kognitivnih funkcija tokom procesa starenja. Zbog toga se pretpostavlja da je održavanje strukturalne celovitosti bele mase jedan od ključnih faktora koji doprinose očuvanju viših kognitivnih funkcija koje su neophodne za nezavisno funkcionisanje u starijem životnom dobu. Fizička aktivnost takođe deluje preko cerebrovaskulnih mehanizama kao što su očuvanost elastičnosti i integriteta zidova krvnih sudova. Osim pomenutog, postoji povezanost između lagane fizičke aktivnosti i integriteta bele mase posebno u temporalnom lobusu. Zaključci pojedinih istraživanja ukazuju na postojanje odnosa između ε4 genskog alela i brain derived neurotrophic factor (BDNF) odgovora na fiziološku adaptaciju nastalu fizičkim vežbanjem, za koju se pretpostavlja da pozitivno utiče na neuroprotekciju. Neki autori predlažu program fizičkog vežbanja kao kombinaciju aerobnog i treninga sa primenjenim otporom. Motorička funkcija i kognicija su blisko poezani, a redovna fizička aktivnost i vežbanje je važno za održavanje fizičkog i mentalnog zdravlja