Distribuirani obrambeni mehanizmi za clone napade temeljeni na algoritmu za istraživanje gravitacije (GSA) u WSN

Wireless Sensor Networks (WSN) are often deployed in hostile environment and are vulnerable to attacks because of the resource constrained nature of the sensors. Clone attack in WSN is one of the major issues where the messages are eavesdropped, the captured node is cloned, and multiple nodes with same identity are produced by attacker. In order to overcome these issues, in this paper, a Distributed Defense Mechanism for Clone Attacks based on Gravitational Search Algorithm (GSA) in WSN is proposed. For efficiently detecting the suspect nodes, the nodes in the channel can be divided into witness node and the claimer node. The witness nodes are responsible for the suspect nodes detection, whereas the claimer nodes should provide their identities for the detection process. For the witness nodes selection, we utilize the GSA to pick out the best witness nodes set. After selecting the witness nodes, clone attack detection is performed by observing the behavior of the neighbor nodes. On detecting the clone attack, revocation procedure is triggered to revoke the clone attack in the witness nodes. By simulation results, it can be concluded that the proposed algorithm provides better protection to clone attacks by reducing the packet drop and increasing the packet delivery ratio.Bežične senzorske mreže (WSN) često su raspoređene u neprijateljskom okruženju i ranjive su na napade zbog prirode senzora koji su tehnološki ograničeni. Clone napad u WSN jedan je od glavnih problema gdje se poruke prisluškuju, zarobljeni čvor se klonira te napadač proizvede višestruke čvorove istog identiteta. Kako bi nadvladali te probleme, ovaj rad predlaže distribuirani obrambeni mehanizam za clone napade temeljen na algoritmu za istraživanje gravitacije (GSA) u WSN. Kako bi se sumnjivi čvorovi efikasno detektirali, čvorovi u kanalu mogu se podijeliti u čvorove svjedoke i tražene čvorove. Čvorovi svjedoci odgovorni su za otkrivanje sumnjivih čvorova, dok traženi čvorovi trebaju za potrebe procesa detekcije navesti svoj identitet. Za izbor čvorova svjedoka, koristi se GSA kako bi se izabrala grupa čvorova koji su najprikladniji. Nakon izbora čvorova svjedoka, otkivanje clone napada vrši se promatranjem ponašanja susjednih čvorova. Otkrivanjem clone napada aktivira se proces opoziva kako bi se opozvao clone napad u čvorovima svjedocima. Prema rezultatima dobivenim iz simulacije može se zaključiti kako predloženi algoritam pruža bolju zaštitu od clone napada smanjivanjem odbacivanja paketa i povećavanjem omjera isporuke paketa

STUDY OF SALIVARY PH IN PATIENTS WITH THE PREVALENCE OF PERIODONTITIS WITH OR WITHOUT DIABETES MELLITUS

ABSTRACTObjective: To assess the relationship between salivary pH and periodontitis in subjects with and without diabetes mellitus. The relationship betweendiabetes mellitus and salivary pH has been assessed. The relationship between periodontitis and salivary pH has been assessed.But the relationshipbetween diabetes mellitus, periodontitis and salivary pH among adults has received less attention.Methods: A total of sixty subjects were evaluated in the study with no history of diabetes mellitus and periodontitis, with periodontitis but no historyof diabetes mellitus, with periodontitis and diabetes mellitusas twenty in each group.pH strips were used to measure the salivary pH.Results: The results show that a decreased salivary pHwas seen in subjects having periodontitis with diabetes as compared to subjects havingperiodontitis without diabetes.Conclusion: Thus diabetes mellitus have a direct effect on salivary pH, reducing it from normal levels.Keywords: Periodontitis, Diabetes mellitus, Salivary pH

A prospective, randomized study to assess the effect of pneumoperitoneum on arterial and endtidal carbondioxide pressure gradient during laparoscopic surgery in adults

INTRODUCTION: During laparoscopic surgery, Carbondioxide pneumoperitoneum is created resulting in hypercarbia which has complex effects on various systems of our body. PURPOSE: To assess the effects of pneumoperitoneum on arterial and end tidal carbondioxide pressure gradient during laparoscopic surgery in adults. METHODOLOGY: 60 patients of ASA 1 & 2 between the age of 20 to 60 years posted for elective laparoscopic appendicectomy or cholecystectomy were selected. They were anaesthesized, Intubated, paralysed and ventilated with constant ventilator settings (TV=10ml/kg, RR=12 to 14/mins). Intra abdominal pressure was maintained between 10-12 mmHg. Arterial blood sample were collected preinsufflation of CO2 and also intra operatively 15 minutes after CO2 pneumoperitoneum. We decided to study the changes in PaCO2, ETCO2, P(a-Et)CO2 gradient, and PH and bicarbonate. Also studied the hemodynamic changes due to pneumoperitoneum. RESULTS: There was significant increase in ETC02, PaCO2, P(a-Et)CO2 gradient, after CO2 insufflation but within clinically normal range. There was decrease in pH without change in bicarbonate concentration. And also slight increase in heart rate and diastolic blood pressure. CONCLUSION: There was increase in ETCO2 and PaCO2, P(a-Et)CO2 gradient significantly higher than pre insufflation value but with in physiological range. The arterial and endtidal carbondioxide pressure gradients are under the normal limits even after CO2 pneumoperitoneum in ASA 1 and 2 patients. The normal pressure P(a-Et)CO2 gradient implies adequate ventilation to alveoli and perfusion. ETCO2 correlate well with PaCO2. So it is best parameter to diagnose hyper carbia

DNA cleavage and antitumour activity of platinum(II) and copper(II) compounds derived from 4-methyl-2-N-(2-pyridylmethyl)aminophenol: spectroscopic, electrochemical and biological investigation

The reaction of the redox-active ligand, Hpyramol (4-methyl-2-N-(2-pyridylmethyl)aminophenol) with K2PtCl4 yields monofunctional square-planar [Pt(pyrimol)Cl], PtL-Cl, which was structurally characterised by single-crystal X-ray diffraction and NMR spectroscopy. This compound unexpectedly cleaves supercoiled double-stranded DNA stoichiometrically and oxidatively, in a non-specific manner without any external reductant added, under physiological conditions. Spectro-electrochemical investigations of PtL-Cl were carried out in comparison with the analogue CuL-Cl as a reference compound. The results support a phenolate oxidation, generating a phenoxyl radical responsible for the ligand-based DNA cleavage property of the title compounds. Time-dependent in vitro cytotoxicity assays were performed with both PtL-Cl and CuL-Cl in various cancer cell lines. The compound CuL-Cl overcomes cisplatin-resistance in ovarian carcinoma and mouse leukaemia cell lines, with additional activity in some other cells. The platinum analogue, PtL-Cl also inhibits cell-proliferation selectively. Additionally, cellular-uptake studies performed for both compounds in ovarian carcinoma cell lines showed that significant amounts of Pt and Cu were accumulated in the A2780 and A2780R cancer cells. The conformational and structural changes induced by PtL-Cl and CuL-Cl on calf thymus DNA and phi X174 supercoiled phage DNA at ambient conditions were followed by electrophoretic mobility assay and circular dichroism spectroscopy. The compounds induce extensive DNA degradation and unwinding, along with formation of a monoadduct at the DNA minor groove. Thus, hybrid effects of metal-centre variation, multiple DNA-binding modes and ligand-based redox activity towards cancer cell-growth inhibition have been demonstrated. Finally, reactions of PtL-Cl with DNA model bases (9-Ethylguanine and 5'-GMP) followed by NMR and MS showed slow binding at Guanine-N7 and for the double stranded self complimentary oligonucleotide d(GTCGAC)(2) in the minor groove

Saturation properties and incompressibility of nuclear matter: A consistent determination from nuclear masses

Starting with a two-body effective nucleon-nucleon interaction, it is shown that the infinite nuclear matter model of atomic nuclei is more appropriate than the conventional Bethe-Weizsacker like mass formulae to extract saturation properties of nuclear matter from nuclear masses. In particular, the saturation density thus obtained agrees with that of electron scattering data and the Hartree-Fock calculations. For the first time using nuclear mass formula, the radius constant $r_0$=1.138 fm and binding energy per nucleon $a_v$ = -16.11 MeV, corresponding to the infinite nuclear matter, are consistently obtained from the same source. An important offshoot of this study is the determination of nuclear matter incompressibility $K_{\infty}$ to be 288$\pm$ 28 MeV using the same source of nuclear masses as input.Comment: 14 latex pages, five figures available on request ( to appear in Phy. Rev. C

Masses of Multiquark Droplets

The mass formulae for finite lumps of strange quark matter with $u$, $d$ and $s$ quarks, and non-strange quark matter consisting of $u$ and $d$ quarks are derived in a non-relativistic potential model. The finite-size effects comprising the surface, curvature and even, the Gauss curvature were consistently obtained, which shows a converging trend. It is found that there is a possibility for the formation of metastable strangelets of large mass. The model predicts low charge to mass ratio as the characteristic signature of strange matter in agreement with the relativistic studies. This study also yields an independent estimate for the bag energy density $B$, which is in agreement with the M.I.T bag model value.Comment: 24pages + 5 figures available upon request,Latex,IP/BBSR/93-3

Origin of subthreshold K^+ production in heavy ion collisions

We investigate the origin of subthreshold $K^+$ production in heavy ion collisions at intermediate energies. In particular we study the influence of the pion induced $K^+$ creation processes. We find that this channel shows a strong dependence on the size of the system, i.e., the number of participating nucleons as well as on the incident energy of the reaction. In an energy region between 1--2 GeV/nucleon the pion induced processes essentially contribute to the total yield and can even become dominant in reactions with a large number of participating nucleons. Thus we are able to reproduce recent measurements of the KaoS Collaboration for 1 GeV/nucleon Au on Au reactions adopting a realistic momentum dependent nuclear mean field.Comment: 6 pages Latex using RevTex, revised version accepted for publication in Phys. Rev.

Role of isospin dependent mean field in pion production in heavy ion reactions

The importance of a isospin dependent nuclear mean field (IDMF) in regard to the pion production mechanism is studied for the reaction $Au+Au$ at 1 GeV/nucleon using the Quantum Molecular Dynamics (QMD) model. In particular, the effect of the IDMF on pion spectra and the charged pion ratio are analyzed. It is found that the inclusion of a IDMF considerably suppresses the low$-p_t$ pions, thus, leading to a better agreement with the data on pion spectra. Moreover, the rapidity distribution of the charged pion ratio appears to be sensitive to the isospin dependence of the nuclear mean field.Comment: 16 pages, using RevTex, 6 PS-Figure