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Issue Info: 
  • Year: 

    1386
  • Volume: 

    14
Measures: 
  • Views: 

    927
  • Downloads: 

    0
Abstract: 

تحقیقات انجام شده نشان می دهد که مورفولوژی استخوان بستگی به بارهای مکانیکی وارد به آن دارد، فرآیندی که این وابستگی را کنترل می کند «نوسازی» نامیده می شود. با توجه به پیروی استخوان از اصول بهینه سازی، در این مقاله از روش بهینه سازی ساختاری LEVEL Set برای مدلسازی همزمان فرآیند های نوسازی داخلی و خارجی استخوان پروکسیمال فمور استفاده شده است. همچنین برای بررسی اثر وجود تخلخل و در نتیجه دانسیته ظاهری متغیر در شکل استخوان اسفنجی مدلساری ها در دو مرحله، مرحله اول با فرض دانسیته ثابت و مرحله دوم با فرض دانسیته متغیر برای استخوان، انجام شده است که نتایج حاصله نشاندهنده یکسان بودن تقریبی هندسه خارجی استخوان و تفاوت قابل ملاحظه ای در هندسه داخلی و وزن آن در دو مرحله مدلسازی است. در نهایت برای اثبات درستی روش، نتایج حاصله با نتایج تجربی حاصل از تصویربرداری اشعه ایکس و برخی از مقالات ارایه شده در این زمینه مقایسه شده است.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    24
  • Issue: 

    3 (68)
  • Pages: 

    156-164
Measures: 
  • Citations: 

    0
  • Views: 

    887
  • Downloads: 

    0
Abstract: 

Background and Aims: Lasers with different characteristics have been used to stimulate orthodontic tooth movement. Considering the contradictory findings in this regard, this study was designed to assess the effect of low LEVEL laser therapy (LLLT) on the rate of orthodontic tooth movement.Materials and Methods: In this randomized clinical trial study, 12 patients (4 boys and 8 girls; average age: 16.9±3.4) with extracted upper first premolars and required canine retraction into extraction site were included. While in both sides canines were retracted by NiTi coil spring, one side was exposed to GaAlAs laser (890 nm). LLLT was done (on the buccal and palatal mucosa by slow movement of probe) at the beginning of the first month. Impression and cast fabrication performed at the beginning of retraction, one and two months later. The amount of retraction on the cast was measured with the aid of a reference plaque fabricated on the rogae using a digital caliper. Data were analyzed using paired sample T-test and one-sample Kolmogorov-Simirnov test.Results: There was no significant difference in the amounts of canine movement between laser exposed and control sides (P>0.05).Conclusion: The energy dose of laser used in this study (72 J per each tooth) was not appropriate for increasing dental movement.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    43
  • Issue: 

    4
  • Pages: 

    492-498
Measures: 
  • Citations: 

    0
  • Views: 

    366
  • Downloads: 

    405
Abstract: 

Background: The purpose of this study was to determine the LEVEL of heat STRESS to construction workers using Thermal Work Limit (TWL) and Wet Bulb Globe Temperature (WBGT) indices and by measuring Urine Specific Gravity (USG) among construction workers in Iran and comparing the appropriateness of these indices for measuring heat STRESS in Iran climate.Methods: This comparative and experimental study was conducted during September 2012 in Baghe Ketabe Tehran, one of the large size construction sites in Tehran City, Iran. Sixty participants were randomly selected in two groups (exposed to sun and non-exposed) among the construction workers in a construction campus with similar work type, climate and diet. TWL and WBGT and USG were measured in two consequent days and at the beginning, mid and end of the work shift, for both groups.Results: The mean WBGT index was 22.6±0.9oC for control group and 27.5±1.2oC for exposure group, the mean TWL index measure was 215.8±5.2 W/m2 for control group and 144±9.8 W/m2 for exposure group and the mean USG was 1.0213±0.0054 in control group and 1.026±0.005 in exposure group. There was a significant difference in TWL, WBGT and USG between exposed and non-exposed group (P<0.01).Conclusion: workers were at an allowed LEVEL of heat STRESS. TWL, WBGT and USG measures were significantly correlated; however as TWL LEVEL enabled classification based on required intervention, it had some merit over WBGT index.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    48
  • Issue: 

    1
  • Pages: 

    49-62
Measures: 
  • Citations: 

    0
  • Views: 

    94
  • Downloads: 

    9
Abstract: 

In order to properly understand the subsurface structures, the issue of inversion of geophysical data has received much attention from researchers. Since accurate reconstruction of the shape and boundaries of the mass using gravimetric data is very important in some issues, it is important to use an effective and efficient method that has a high ability to draw and reconstruct the boundaries of a mass. In recent years, the LEVEL set method introduced by Asher and Stein has been widely used to solve this problem. From the expansion of the LEVEL set function in some bases of the problem, the effective number of parameters is greatly reduced and an optimization problem is created which its behavior is better than the least squares problem. As a result, the LEVEL set parameterization method will be presented for the reconstruction of inversion models. A common advantage of the parametric LEVEL set method is the careful examination of the boundary for optimum sensitivities, which significantly reduces the dimensional problem, and many of the difficulties of traditional LEVEL set methods, such as regularization, reconstruction, and basis function. LEVEL set parameterization is performed by radial basis functions (RBF),which causes an optimal problem with an average number of parameters and high flexibility,and the computational and optimization process for Newton's method is more accurate and smooth. The model is described by the zero contour of a LEVEL-set function, which in turn is represented by a relatively small number of radial basis functions. This formulation includes some additional parameters such as the width of the radial basis functions and the smoothness of the Heaviside function. The latter is of particular importance as it controls the sensitivity to changes in the model. In this algorithm adaptively chooses the required smoothness parameter and tests the method on a suite of idealized Earth models. In this evolutionary approach, the reduction gradient method usually requires many iterations for convergence, and the functions are weakened for low-sensitivity problems. Although the use of Quasi-Newton methods to improve the LEVEL set function increases the degree of convergence, they are computationally challenging, and for large problems and relatively finer grids, a system of equations must be solved in each iteration. Moreover, based on the fact that the number of underlying parameters in a parametric approach is usually much less than the number of pixels resulting from the discretization of the LEVEL set function, we make a use of a Newton-type method to solve the underlying optimization problem. In this research, the algorithm is used to investigate its strengths and weaknesses for applying geophysical gravity data, coding and programming, and it is tested using several two-dimensional synthetic models. Finally, the method is tested on gravity data from the Mobrun ore body, north east of Noranda, Quebec, Canada. The results of this study show that the application of the optimization algorithm of the LEVEL set function will lead to a relatively more accurate and realistic detection of mass boundaries. It shows that the tested mass has spread from a depth of 10 meters to a depth of 160 meters.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    21
  • Issue: 

    73
  • Pages: 

    1-5
Measures: 
  • Citations: 

    0
  • Views: 

    3650
  • Downloads: 

    0
Abstract: 

Background and aim: Today, STRESS is a part of life that is unavoidable and is considered one of the risk factors in heart diseases. The aim of this study was to determine the effect of STRESS management training on STRESS LEVELs of cardiac patients hospitalized in Imam Khomeini Hospital.Materials and methods: This quasi experimental study was conducted on 60 cardiac patients hospitalized in Imam Khomeini hospital. The sample randomly was assigned in experimental and control groups. The experimental group received STRESS management training and the control group received usual care. STRESS LEVEL was measured and compared before and after intervention. Data collected by using questionnaire include demographic profile and SCL 90 (Symptom Check List 90). Face validity and content validity questionnaire was confirmed. The reliability was evaluated. Test-retest 0.78 was confirmed. The resulted data were analyzed by SPSS software, version 16.Findings: The results showed that the mean and standard deviation of the age in experimental group was 47±9.34. In control group was 47.1±10.96. Based on the results, 53.3% female, 60% in Tehran, 26.7% in high education LEVEL and 60% were working. Disease duration of 33.3% in 4-6 years and 86.7% had a history of hospitalization. Mean STRESS in the experimental group was (before=146±37, after=95±19.6) and in the control was (before=135.9±54.2, after=132±41) respectively. T test showed that after intervention a significant statistical difference appears between two groups (P=0.000). Age and previous hospitalization were associated with STRESS LEVELs significantly.Conclusion: STRESS management programs can reduce STRESS in heart disease. The nurses, who are in close relationship with these patients, can have an important role in educating and supporting them.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2023
  • Volume: 

    3
  • Issue: 

    1
  • Pages: 

    31-45
Measures: 
  • Citations: 

    0
  • Views: 

    172
  • Downloads: 

    11
Abstract: 

More than 22% of the world's agricultural land is saline, and this trend continues to increase with climate changes. Salinity STRESS causes leaf color change, osmotic STRESS, ionic toxicity, prevents growth, photosynthesis and plant performance. Due to their size less than micron, metal nanoparticles have a great absorption and transmission power in plants. Salinity STRESS is a major problem in hot and dry areas under tomato cultivation. For this purpose, investigating the mutual effects of the size and type of zinc oxide and iron oxide nanoparticles on the improvement and change of growth and increasing the resistance to salt STRESS in tomato plants of the early urbana variety were carried out in the form of a completely randomized and factorial design with 4 replications, at a significant LEVEL of 5%. In this research, zinc oxide nanoparticles in 25 and 50 nm sizes, iron oxide in 25 nm sizes and sodium chloride in 0 and 75 mM LEVELs were used. Nanoparticles and salinity treatments were both applied to the plants. The results showed that salt STRESS led to a decrease in plant growth parameters such as shoot and root length, leaf area, RWC, ion leakage. Also, NaCl led to an increase in the accumulation of prolin and other aldehydes, sodium, iron and zinc. The application of nanoparticles had a slight effect in STRESS-free conditions, but in STRESSed conditions, these two nanoparticles alone and especially in combination neutralized the effect of salinity and reduced the damage caused by salinity STRESS.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

Issue Info: 
  • Year: 

    2017
  • Volume: 

    22
  • Issue: 

    2
  • Pages: 

    145-148
Measures: 
  • Citations: 

    2
  • Views: 

    81
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2006
  • Volume: 

    64
  • Issue: 

    9
  • Pages: 

    46-54
Measures: 
  • Citations: 

    0
  • Views: 

    1861
  • Downloads: 

    0
Abstract: 

Background: The most frequently used test for evaluation of fetal health is the Non STRESS Test (NST). Unfortunately it has a high incidence of false positive results. The combination of vibroacoustic stimulation with the NTS has been shown to reduce non reactive results.Methods: A tests assessment method was chosen with a simple randomized sampling. 40 pregnant women with non reactive NST in the first 20 minutes who received VAS in one of Tehran University's Hospitals were compared with BPP scores. A vibroacoustic stimulation was applied for a 3 seconds on the maternal abdomen and fallowed within 10 minutes. Data collection tools were NST, sonography instruments, NST result paper, tooth brusher, watch, demographic questioner and check list. Data analysis was made by descriptive static and by using the Fisher's Exact Test (with LEVEL of significant at p<0/05). All statistical analysis were performed using an spss/win.Results: After VAS, 70% of non reactive tracing became reactive. All cases with fetal reactivity response after a VAS had a subsequent BPP score of 8 (negative predictive value of 100%). False positivity of VAS was lower than NST.Conclusion: VAS offers benefits, by decreasing the incidence of non reactive test and reducing test time. VAS lowers the rate of false positive NST. VAS is safe and allows more efficient of prenatal services. This test could be used as a rapid antepartum test to predict fetal well-being.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    1390
  • Volume: 

    -
  • Issue: 

    1
  • Pages: 

    0-0
Measures: 
  • Citations: 

    1
  • Views: 

    264
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2010
  • Volume: 

    23
  • Issue: 

    1 (62)
  • Pages: 

    21-26
Measures: 
  • Citations: 

    0
  • Views: 

    814
  • Downloads: 

    0
Abstract: 

Background and Aims: Lasers with different characteristics have been used to stimulate orthodontic tooth movements and to inhibit the pain during tooth movements. Considering the contradictory finding in this respect, the effect of low LEVEL laser therapy (LLLT) was evaluated on the pain during orthodontic tooth movement.Materials and Methods: In this randomized clinical trial study, 12 patients were included with extracted upper first premolars and required canine retraction into extraction site. While in both sides canines were retracted by Niti coil spring, one side was exposed to GaAlAs laser (890 nm). LLLT was done on the buccal and palatal mucosa by slow movement of probe. The patients were asked about their pain on both sides 2 days after beginning of retraction. Pain measurement was evaluated with VAS.Results: Pain perception in LLLT side was significantly decreased (P=0.007).Conclusion: Based on the results, single irradiation of GaAlAs laser (12 J energy per tooth) can decrease pain perception.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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