Introduction: Long-term clinical evaluation of dental implants and their surrounding structures is of utmost importance to acquire knowledge about reasons for implant success and failure.However, accurate and reproducible results are difficult to obtain. The aim of the present study was to examine bone height around endosseous implants on digital conventional radiographs (DCR) and direct digital subtraction images (DSI) prior to loading.Materials and methods: In this experimental study, bone height around 10 implants in 6 patients was assessed by 2 observers. Standardized digital radiographs were obtained just a week and 3 months postoperatively and subtracted by means of EMAGO software. Then the observers evaluated bone height on DCRs and DSIs. MINITAB software and paired t-test were used for statistical analysis (a=0.05).Results: Comparative evaluation of bone height indicated significantly higher values on DCR than on DSI (p value=0.002). The observers also had statistically significant variability in this assessment (p value=0.00003).Conclusion: DSI demonstrated lower values of linear measurement of bone height around endosseous implants compared with DCR. Interobserver variability should be considered when comparing values from follow-up studies.

Introduction and Objective: Rapid, low-cost and accurate estimation of tree metrics in the forest ecosystem is one of the challenges facing forest managers and inventories. Therefore, given that the forest areas of northern of Iran, mainly deciduous and uneven-aged forests, are covered with various tree species of different sizes, mensuration techniques could be developed and established to suit the particular circumstances. Methods used in forest inventory should be userfriendly, repeatable, relatively low cost, and also have high accuracy and precession for forest inventory operation. Materials and Methods: Thanks to technological advances in the photography industry, one of the attractive and proposed methods could be the use of digital cameras, in which the potential and performance of this method was evaluated to estimate diameter at different heights of trees. For this purpose, using a digital camera which is mounted on a pre-designed horizontal index and in different shooting distance, diameter at stump height, DBH, and diameter at top of trunk for 108 trees, in REFTMU and in the altitude range of 750 to 1100 meters above sea level and in autumn was estimated. The distance from each shooting station to each tree was captured using the audio and laser rangefinder of the Vertex device as well as the laser meter. Results: The overall results showed that at 95% significance level, there was a significant difference with real data only in estimating the diameter at stump height. It is also showing an underestimation in estimating the diameter at breast height and at the top of trunk, and in estimating the upper trunk diameter, it was overestimated. The lowest amount of %CV. RMSE was also observed in estimating breast diameter (4. 99%). Conclusion: The evaluated method showed that in the middle classes of metrics captured data, it was more accurate and less error than the upper and lower classes. The results also showed that with increasing the distance of the shooting point, the error rate was increased. Consequently, the results of time study showed that the average operational time for capturing data in digital camera and the traditional method were 3. 88 min. tree-1, and 3. 42 min. tree-1, respectively.

Background & Aim: The majority of carious lesions are not well-defined radiolucencies. Approximately 40% demineralization is required for radiographic detection of a lesion. The actual depth of penetration of carious lesion is deeper than may be detected radiographically. However, digital subtraction images permit to detect 1-5% decrease of mineral mass per unit volume. The goal of the present study was to evaluate the accuracy of digital subtraction radiography in the detection of dental demineralization in vitro.Methods & Materials: This study was based on observational-diagnostic method which was done on 30 extracted human teeth, categorized in two groups A and B, each having 15 members. In each of teeth, one approximal enamel demineralization lesion was induced using an acidified system (PH=4.8). Direct digital radiography were obtained under standardized condition of teeth before demineralization. After 7 days, the teeth of group B and after 42 days, group A removed from acid and new radiographs were taken. The images of the 7th and 42nd days were subtracted from the baseline radiograph (before creation of the lesion). Then teeth were histologically evaluated. Direct digital and subtraction images were interpreted by three observers to detect presence or absence of the lesion, then the diagnostic accuracy of both methods was determined.Results: After 7 days, the sensitivity, specificity, accuracy, positive predictive value and negative predictive value for incipient lesions in direct digital radiography were 0%, 80%, 40%, 0% and 44% respectively and in digital subtraction radiography were 66.7%, 86.7%, 76.7%, 83.4% and 72.3% respectively. However after 42 days the sensitivity, specificity and accuracy of both methods were 100%.Conclusion: Digital subtraction radiography has a fairly acceptable accuracy in detection ofthe incipient proximal lesions in comparison with DDR. For moderate proximal lesions DSR has the same accuracy as DDR.

High gain Balun-low-noise-amplifier (LNA) is proposed for tuner of digital televisions (DTVs). The proposed Balun-LNA is based on CS-CG (common-source-common-gate) structure. To improve the isolasion and frequency response, Balun-LNA has cascode transistors before load resistors. Balun-LNA uses current-bleeding circuit to increasie transconductance of CS transistor, so that current-bleeding transistor has transconductance of N-1 times larger than transconductance of cascode transistor. Thereby, transconductance and current of CS transistor are increased N times, as N-1 times of current pass to current-bleeding transistor. Therefore current of CG and CS stages stay identical. Also, Balun-LNA employs a positive feedback to satisfy input impedance matching and CG transistor has higher transconductance. By increasing transconductance of CS and CG transistors, the proposed Balun-LNA achieves to high voltage gain. Accordingly, CG and CS tansistors have symmetrical currents and loads at the differential output of the proposed Balun-LNA. Symmetrical loads cause the balanced differential outputs. This proposed Balun-LNA is designed in 90-nm CMOS technology and covers the frequency range of 40 MHz to 1GHz. This Balun-LNA achieves the voltage gain of 22.6 dB, S11 of less than -10 dB and the Minimum NF of 5 dB. This Balun-LNA operates at the nominal supply voltage of 2.2v.

Background and Aim: Digital subtraction Radiography (DSR) is a method of accurate assessing condylar head changes. several studies have been carried out in applying DSR in dentistry, however there is a few number of studies in efficacy of DSR method in assessment of condylar head changes, The aim of this study was to compare panoramic radiography and DSR detecting simulated lesions of the mandibular condyl.Materials and Methods: this was a process research study, in which two dry human skulls with no obvious temporomandibular joint pathology were used. Osteophytic lesions were simulated using three sizes of bone chips that were placed on the medial portion of anterior and superolateral aspects of the condyle. Osteolytic lesions were simulated making 1 and 2 mm holes using round burr in the central portion of anterior aspect and Lateral pole of the condyle. Panoramic radiographs were prepared with and without the lesions in place. These paired radiographs were digitized and digital- subtraction images of the original panoramic images were obtained. Eight observers evaluated 155 images of each modality for the presence or absence and the type of simulated lesions of the mandibular condyle. Sensitivity, specificity, reliability and measure of agreement were analyzed using kappa test and crossed tables and qualitative variables were assess by chi-square and fisher’s Exact test.Results: Specificity of panoramic and DSR methods were 15.4% and 66.7% respectively. Sensitivity of panoramic and DSR methods were 61.1% and 80.6% for osteophytic lesions and 37.5% and 83.3% for Osteolytic lesions. The percentage of correct decisions made in DSR method was significantly more than conventional panoramic method (82.6%vs 41.9%) (p<0.0001).Conclusion: Based on the results of this study digital subtraction technique was significantly more accurate than the panoramic radiographs in detection of simulated lesions of the mandibular condyle.

Suffix trees are the most frequently used data structures in algorithms on words. In this paper, we consider the depth of a compact suffix tree, also known as the PAT tree, under some simple probabilistic assumptions. For a biased memoryless source, we prove that the limiting distribution for the depth in a PAT tree is the same as the limiting distribution for the depth in a PATRICIA trie, even though the PATRICIA trie is constructed from statistically independent strings. As a result, we show that the limiting distribution for the depth in a PAT tree built over n suffixes is normal.

This paper de nes the concept of partitioned hypergraphs, and enumerates the number of these hypergraphs and discrete complete hypergraphs. A positive equivalence relation is de ned on hypergraphs, this relation establishes a connection between hypergraphs and graphs. Moreover, we de ne the concept of (extended) derivable graph. Then a connection between hypergraphs and (extended) derivable graphs was investigated. Via the positive equivalence relation on hypergraphs, we show that some special trees are derivable graph and complete graphs are self derivable graphs.