Introduction: Usually osseointegration takes between three to six months after implant placement but patients are interested to have early loading. There are no definitive criteria for measuring bone mineral density (BMD), insertion torque (IT) (final torque force) and resonance frequency analysis (RFA) (primary implant stability) to determine exact loading time based on the relationship between the above-mentioned parameters. The aim of this study was to determine the relationship between IT, RFA and BMD in screw-type implants.Materials and Methods: This clinical trial was conducted on 18 patients who were candidates for ITI implant placement. Written consent was taken and jaw bone density was determined via a digital radiography technique before surgery. After implant placement, RFA and IT were measured. Fifty-five ITI implants of the total 62 implants placed were evaluated; the implants were 12 mm long with a diameter of 4.1 mm. Data was analyzed with Pearson’s test using SPSS.15 software (a=0.05).Results: There was a significant relationship between IT, RFA and BMD. Pearson’s test showed a correlation coefficient of 0.872 to 0.789 between the three parameters, indicating a strong relationship between them. The mean bone density was 1.468±0.042 g/cm2; the mean RFA was 66.01±2.2 ISQ and the mean IT was 34.62±3.33 N/cm2.Conclusion: Based on the results of the present study there is a significant relationship between, IT, RFA and BMD (p value=0.001).

Health monitoring allows small failures and damages to be identified and fixed before they turn into major and irreparable damages, to prevent loss of life and to make it possible to reinforce or improve it at the lowest cost. Currently, in the field of civil engineering, the health monitoring of structures is done in sensitive structures. One of the parts of the structure that may suffer initial damage before loading and during implementation due to difficulty in implementation is Concrete Filled Tube (CFT)columns.  One of the most likely damages in CFT columns is interface debonding damage. This damage causes the column to become weak and not benefit from the characteristics of steel and concrete together. Accordingly, in the present study, this damage and its severity in seismic (dynamic) parameters have been investigated. The results of the study show that damage causes changes in the mode shape of the structure, and it has caused a 6.38% reduction in the frequency in the first (main) mode of the structure. Also, the damping of the damaged specimen is reduced by approximately 12% compared to the healthy specimen. On the other hand, the results show that the severity of damage is very effective in changing seismic parameters. So that by doubling the damage area, the frequency decreased by approximately 0.35% and reached from 873.27 Hz to 20.870.20 Hz, but the mode shape of damage did not affect the frequency

We spend one third of our life in sleep. The interesting point about the sleep is that the neurons are not quiescent during sleeping and they show synchronous oscillations at different regions. Especially sharp wave ripples are observed in the hippocampus. Here, we propose a simple phenomenological neural mass model for the CA1-CA3 network of the hippocampus considering the spike frequency adaptation for excitatory neurons. The model consists of one group of identical CA1 excitatory neurons, one group of identical CA1 inhibitory neurons, one group of identical CA3 excitatory neurons, and one group of identical CA3 inhibitory neurons. All the recurrent connections between the neurons of CA3 network are considered. For CA1 neurons the excitatory to inhibitory, inhibitory to excitatory and inhibitory to inhibitory connections are considered. CA1 and CA3 neurons are connected by long-range connections from CA3 excitatory neurons to both CA1 excitatory and inhibitory neurons. We show that this simple model can spontaneously generate the oscillations similar to the sharp waves in the CA3 network. The duration of the sharp waves is determined by the slow dynamic of the adaptation process. The excitatory inputs from CA3 network to the CA1 network during these sharp waves induce ripples in the CA1 network due to the interaction of excitatory and inhibitory neurons. We next show that contrary to intuition and in a very good agreement with the recent experimental findings, reduction of the excitation increases the amplitude of the ripples while decreases the frequency of them. This model can also spontaneously generate ripple doublets. The decrease in the excitation is associated with the increase in the probability of observing ripple doublets. Our results shed light on our understanding of the mechanism underlying the generation of sharp wave ripples.

Background and aim: Results of Implant therapy have always been evaluated on the basis of radiographic and clinical assessments such as percussion, focused only on determination of peri-implant bone resorption and implant failures. These measurements are qualitative only and could not be considered as quantitative and reliable scales for the evaluation of stability; So they could not be statistically analysed. These difficulties could be overcome by using Resonance frequency Analysis (RFA).RFA could be considered as a proper comparable measurement in evaluation of implant stability. This study aimed to evaluate and determine the stability of over denture loaded implants in a number of private clinics during 2006 -2007.Materials and Methods: This cross – sectional study was conducted on 13 patients provided with Swiss plus implant Therapy loaded by over dentures for the first step, each patient was evaluated regarding Implant Quality health Scale and put into one of five groups. Abutments were then removed and fixtures were evaluated by Osstell Mentor Instrument following the attachment of Smart peg to fixtures, Implant Stability Qoutient was then determined. Sampling was done in a sequential approach and obtained data were statistically analyzed using X2 and t-test.Results: Fourty three implants were evaluated in 13 patients, 21 in maxilla and 22 in mandible the mean I.S.Q.Equaled 70.36 ± 4.43 in maxilla and 79.1 ± 3.51 in mandible. The total mean ISQ (bimaxillary mean ISQ) equaled 84.36 ± 5.94.Conclusion: Regarding the obtained results, Over denture loaded implants are absolutely successful treatment plans in mandible, according to their higher ISQ compared to maxilla. It is also demonstrated that stability of implants at each step of treatment Procedure is influenced by primary stability during placement more than any other factors. Primary stability itself is mainly influenced by surgeon`s experience in the proper following of surgical protocol.

Background and Aim: It has been several decades since the technology of frequency lowering (FL) has been proposed. However, primary research has revealed no benefits regarding the use of this technique. Currently, new methods for FL and improvement of perception of speech and fricative sounds have led to the application of these methods by numerous companies to produce hearing aids. In this study, through reviewing the findings of recent studies we introduced several FL techniques used in various companies.Recent Findings: Results of studies conducted since the year 2000 on FL technology suggested that this technology could be used to improve speech perception in cases of high frequency hearing loss. Today, the majority of hearing aid manufacturers use different FL methods.Conclusion: While the setting principles of FL methods are still vague, improved hearing of fricative sounds has been associated with increased use of this technique by researchers. FL technique has its own benefits and setbacks, understanding of which would facilitate the use of FL techniques and adjustment of hearing aids for hearing-impaired individuals.

It has been shown over several decades of radar research that the exploitation of diversity in a number of domains such as space, frequency, time, polarization, and, recently, waveform can provide increased agility, flexibility, reliability, and capabilities to the radar system. However this is often achieved either through efforts in system design, increased hardware complexity, or by employing additional resources. In the frequency diverse array (FDA) the subsequent antenna elements are fed with stepped discrete frequencies. So a range-angle dependent radiation pattern is made possible. It is possible to apply different frequencies with different patterns to the elements of FDA to achieve different radiation pattern. In this paper, a frequency diverse array with non-uniform inter-element frequency offset called quadratic-FDA has been proposed, that its variation is a function of physical distance of elements from the first element. To produce the coefficient of the frequency offset two frequency offset generators has been proposed. In The first proposed method uses linear distance as a input of function and the second one uses multiples of the roots of the Chebyshev polynomial. The proposed strategy provides a non-periodic beampattern, with a maximum that can be steered in space by selecting appropriate excitation weights of the antennas. This single-maximum beampattern, in contrast to multiple-maxima beampattern of the other forms of FDA, can help to further reject range-dependent interferences, causing improved SINR and increased detectability.