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.

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).

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.

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.

This paper presents a novel approach to detect and estimate cracks in Timoshenko Beams using frequencies and FREQUENCY response functions and extreme learning machine. For this purpose, the extreme learning machine used the three first natural frequencies and FREQUENCY response functions of beam structure as input which may be noisy or noise free and crack states in beam as output. This data is acquired by the analysis of cracked beams applying the finite element method. To demonstrate the potential of the proposed vibration analysis over existing ones, a validation study has been done. The performance of the presented method has been verified through two numerical examples, namely, a cantilever beam and simply supported beam containing single or multi cracks. Results indicate that the proposed method works well in prediction and estimation of crack and obtained results are accurate. Also, the results show that the presented method is sensitive to the location and severity of crack in spite of the noisy modal data.

The electrical connection between the load and source can be eliminated using inductive power transfer. Supplying AC Loads, such as V2G and single phase motors, is one of the many applications of IPT. To supply an AC load, the rectified output power of IPT should be delivered to an inverter. The sequential dc/ac/dc/ac conversions cause IPT efficiency decreases. To make an output AC voltage with acceptable THD, the carrier FREQUENCY of the PWM method should be several times the reference FREQUENCY which increases the switching loss. In this paper based on IPT gain-FREQUENCY characteristics, a new pulse FREQUENCY waveform synthesizing method (PFWS) has been presented. This method eliminates secondary inverter switching losses. It is shown that besides loss reduction, synthesized sinusoidal waveform at secondary of IPT, causes the Total Switching Device Power (TSDP) of secondary converters decrease, therefore their lifetime increase. Simulated and experimental results of the developed laboratory model which verify and illustrate the operation of the proposed method are presented.

This paper presents a new technique for measuring power system FREQUENCY, rate of change of FREQUENCY and the voltage amplitude and phase angle using the Simulated Annealing (SA) based optimization algorithm. The algorithm uses the digitized samples of the voltage signal at the relay location and minimizes a cost function of the sum of the absolute error between the actual estimated signal samples. The proposed algorithm does not need any filter or model for the system FREQUENCY before and during the estimation process. The effects of the number of samples, sampling FREQUENCY and harmonics contamination on the estimated parameters are tested and discussed in the paper.