Assessment of CT numbers in limited and medium field-of-view scans taken using Accuitomo 170 and Veraviewepocs 3De cone-beam computed tomography scanners

To assess the influence of anatomic location on the relationship between computed tomography (CT) number and X-ray attenuation in limited and medium field-of-view (FOV) scans. Materials and Methods Tubes containing solutions with different concentrations of K2HPO4 were placed in the tooth sockets of a human head phantom. Cone-beam computed tomography (CBCT) scans were acquired, and CT numbers of the K2HPO4 solutions were measured. The relationship between CT number and K2HPO4 concentration was examined by linear regression analyses. Then, the variation in CT number according to anatomic location was examined. Results The relationship between K2HPO4 concentration and CT number was strongly linear. The slopes of the linear regressions for the limited FOVs were almost 2-fold lower than those for the medium FOVs. The absolute CT number differed between imaging protocols and anatomic locations. Conclusion There is a strong linear relationship between X-ray attenuation and CT number. The specific imaging protocol and anatomic location of the object strongly influence this relationship.

Validation of cone-beam computed tomography and magnetic resonance imaging of the porcine spine: a comparative study with multidetector computed tomography and anatomical specimens

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

An experimental nonlinear low dynamic stiffness device for shock isolation

The problem of shock generated vibration is very common in practice and difficult to isolate due to the high levels of excitation involved and its transient nature. If not properly isolated it could lead to large transmitted forces and displacements. Typically, classical shock isolation relies on the use of passive stiffness elements to absorb energy by deformation and some damping mechanism to dissipate residual vibration. The approach of using nonlinear stiffness elements is explored in this paper, focusing in providing an isolation system with low dynamic stiffness. The possibilities of using such a configuration for a shock mount are studied experimentally following previous theoretical models. The model studied considers electromagnets and permanent magnets in order to obtain nonlinear stiffness forces using different voltage configurations. It is found that the stiffness nonlinearities could be advantageous in improving shock isolation in terms of absolute displacement and acceleration response when compared with linear elastic elements. Copyright (C) 2015 Elsevier Ltd. All rights reserved

On the effects of mistuning a force-excited system containing a quasi-zero-stiffness vibration isolator

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Exercise training improves ambulatory blood pressure but not arterial stiffness in heart transplant recipients

BACKGROUND: Hypertension is the most prevalent comorbidity after heart transplantation (HT). Exercise training (ET) is widely recommended as a key non-pharmacologic intervention for the prevention and management of hypertension, but its effects on ambulatory blood pressure (ABP) and some mechanisms involved in the pathophysiology of hypertension have not been studied in this population. The primary purpose of this study was to investigate the effects of ET on ABP and arterial stiffness of HT recipients.METHODS: 40 HT patients, randomized to ET (n = 31) or a control group (n = 9) underwent a maximal graded exercise test, 24-hour ABP monitoring, and carotid-femoral pulse wave velocity (PWV) assessment before the intervention and at a 12-week follow-up assessment. The ET program was performed thrice-weekly and consisted primarily of endurance exercise (40 minutes) at similar to 70% of maximum oxygen uptake (Vo(2MAX))RESULTS: The ET group had reduced 24-hour (4.0 +/- 1.4 mm Hg, p < 0.01) and daytime (4.8 +/- 1.6 mm Hg, p < 0.01) systolic ABP, and 24-hour (7.0 +/- 1.4 mm Hg, p < 0.001) daytime (7.5 +/- 1.6 mm Hg, p < 0.001) and nighttime (5.9 +/- 1.5 mm Hg, p < 0.001) diastolic ABP after the intervention. The ET group also had improved Vo(2MAX) (9.7% +/- 2.6%, p < 0.001) after the intervention. However, PWV did not change after ET. No variable was changed in the control group after the intervention.CONCLUSIONS: The 12-week ET program was effective for reducing ABP but not PWV in heart transplant recipients. This result suggesfs that endurance ET may be a tool to counteract hypertension in this high-risk population. (C) 2015 International Society for Heart and Lung Transplantation. All rights reserved.

Use of autogenous bone and beta-tricalcium phosphate in maxillary sinus lifting: a prospective, randomized, volumetric computed tomography study

The correction of bone defects can be performed using autogenous or alloplastic materials, such as beta-tricalcium phosphate (β-TCP). This study compared the changes in bone volume (CBV) after maxillary sinus lifting using autogenous bone (n=12), autogenous bone associated with β-TCP 1:1 (ChronOS; DePuy Synthes, Paoli, CA, USA) (n=9), and β-TCP alone (n=11) as grafting material, by means of cone beam computed tomography (CBCT). CBV was evaluated by comparing CBCT scans obtained in the immediate postoperative period (5-7 days) and at 6 months postoperative in each group using OsiriX software (OsiriX Foundation, Geneva, Switzerland). The results showed an average resorption of 45.7±18.6% for the autogenous bone group, 43.8±18.4% for the autogenous bone+β-TCP group, and 38.3±16.6% for the β-TCP group. All bone substitute materials tested in this study presented satisfactory results for maxillary sinus lifting procedures regarding the maintenance of graft volume during the healing phase before the insertion of implants, as assessed by means of CBCT.

Correlation between volume of apical periodontitis determined by cone-beam computed tomography analysis and endotoxin levels found in primary root canal infection

This clinical study was conducted to correlate the levels of endotoxins and bacterial counts found in primary endodontic infection with the volume of periapical bone destruction determined by cone-beam computed tomography (CBCT) analysis. Moreover, the levels of bacteria and endotoxins were correlated with the development of clinical features. Twenty-four root canals with primary endodontic disease and apical periodontitis were selected. Clinical features such as pain on palpation, pain on percussion, and previous episode of pain were recorded. The volume (cubic millimeters) of periapical bone destruction was determined by CBCT analysis. Endotoxins and bacterial samplings were collected by using sterile/apyrogenic paper points. Endotoxins were quantified by using limulus amebocyte lysate assay (KQCL test), and bacterial count (colony-forming units [CFU]/mL) was determined by using anaerobic culture techniques. Data were analyzed by Pearson correlation and multiple logistic regression (P < .05). Endotoxins and bacteria were detected in 100% of the root canal samples (24 of 24), with median values of 10.92 endotoxin units (EU)/mL (1.75-128 EU/mL) and 7.5 × 10(5) CFU/mL (3.20 × 10(5)-8.16 × 10(6) CFU/mL), respectively. The median volume of bone destruction determined by CBCT analysis was 100 mm(3) (10-450 mm(3)). The multiple regression analysis revealed a positive correlation between higher levels of endotoxins present in root canal infection and larger volume of bone destruction (P < .05). Moreover, higher levels of endotoxins were also correlated with the presence of previous pain (P < .05). Our findings revealed that the levels of endotoxins found in root canal infection are related to the volume of periapical bone destruction determined by CBCT analysis. Moreover, the levels of endotoxin are related to the presence of previous pain.

Mandibular cortical bone evaluation on cone beam computed tomography images of patients with bisphosphonate related osteonecrosis of the jaws

Objectives The objective of this study was to develop a technique for detecting cortical bone dimensional changes in patients with bisphosphonate-related osteonecrosis of the jaw (BRONJ). Study Design Subjects with BRONJ who had cone-beam computed tomography imaging were selected, with age- and gender-matched controls. Mandibular cortical bone measurements to detect bisphosphonate-related cortical bone changes were made inferior to mental foramen, in 3 different ways: within a fixed sized rectangle, in a rectangle varying with the cortical height, and a ratio between area and height. Results Twelve BRONJ cases and 66 controls were evaluated. The cortical bone measurements were significantly higher in cases than controls for all 3 techniques. The bone measurements were strongly associated with BRONJ case status (odds ratio 3.36-7.84). The inter-rater reliability coefficients were high for all techniques (0.71-0.90). Conclusions Mandibular cortical bone measurement is a potentially useful tool in the detection of bone dimensional changes caused by bisphosphonates. Long-term administration of bisphosphonates (BPs) affects bone quality and metabolism following accumulation in bone.1 Since the first cases of bisphosphonate-related osteonecrosis of the jaw (BRONJ) were published in 2003,2 there has been a search for factors that can predict the onset of the condition. Oral and intravenous BPs reduce bone resorption, increase mineral content of bone, and alter bony architecture.3, 4, 5 and 6 Previous studies have demonstrated these changes both radiographically and following histologic analysis.1, 3, 7, 8, 9 and 10 The BP-related jaw changes may present radiological features, such as thickening of lamina dura and cortical borders, diffuse sclerosis, and narrowing of the mandibular canal3 and 11; however, oral radiographs of patients taking BPs do not consistently show radiographic changes to the jaws.11 and 12 The challenge is to find imaging tools that could improve the detection of changes in the bone associated with BP use. Various skeletal radiographic features associated with BRONJ in conventional periapical and panoramic radiographs, computed tomography, magnetic resonance imaging, and nuclear bone scanning have been described.3, 8, 9, 10 and 11 There has also been a search for BP-related quantitative methods for the evaluation of radiographic images, to avoid observer subjectivity in interpretation. Factors thought to be important include trabecular and cortical structure, and bone mineralization.4 Consequently, measurable bone data have been reported in subjects taking BPs through many techniques, including bone density, architecture, and cortical bone thickness.1, 4, 7 and 13 Trabecular microarchitecture of postmenopausal women has been evaluated with noninvasive techniques, such as high-resolution magnetic resonance images showing less deterioration of the bone 1 year after initiation of oral BP therapy.4 A decrease in bone turnover and a trend for an increase in the bone wall thickness has been detected by histomorphometry in subjects taking BPs.1 Alterations in the cortical structure of the second metacarpal have been detected in digital x-ray radiogrammetry of postmenopausal women treated with BPs.7 Mandibular cortical width may be measured on dental panoramic radiographs, and it has been suggested as a screening tool for referring patients for bone densitometry for osteoporosis investigation.14 and 15 Inhibition of the intracortical bone remodeling in the mandible of mice taking BPs has been reported.16 Thus, imaging evaluation of the mandibular cortical bone could be a biologically plausible way to detect BP bone alterations. Computed tomography can assess both cortical and trabecular bone characteristics. Cone-beam computed tomography (CBCT) can provide 3-dimensional information, while using lower doses and costing less than conventional CT. The CBCT images have been studied as a tool for the measurement of trabecular bone in patients with BRONJ.13 Therefore, cortical bone measurements on CBCT of the jaws might also help to understand bone changes in patients with BRONJ. There is no standard in quantifying dimensional changes of mandibular cortical bone. We explored several different approaches to take into consideration possible changes in length, area, and volume. These led to the 3 techniques developed in this study. This article reports a matched case-control study in which mandibular cortical bone was measured on CBCT images of subjects with BRONJ and controls. The aim of the study was to explore the usefulness of 3 techniques for detecting mandibular cortical bone dimensional changes caused by BP.

Comparative analysis between biogas flow in landfill and electrical resistivity tomography in Rio Claro city, Brazil

The biogas originated from anaerobic degradation of organic matter in landfills consists basically in CH4, CO2, and H2O. The landfills represent an important depository of organic matter with high energetic potential in Brazil, although with inexpressive use in the present. The estimation of production of the productive rate of biogas represents one of the major difficulties of technical order to the planning of capture system for rational consumption of this resource. The applied geophysics consists in a set of methods and techniques with wide use in environmental and hydrogeological studies. The DC resistivity method is largely applied in environmental diagnosis of the contamination in soil and groundwater, due to the contrast of electrical properties frequent between contaminated areas and the natural environment. This paper aims to evaluate eventual relationships between biogas flows quantified in drains located in the landfill, with characteristic patterns of electrical resistivity in depth. The drain of higher flow (117 m3 /h) in depth was characterized for values between 8000 Ω⋅m and 100.000 Ω⋅m, in contrast with values below 2000 Ω⋅m, which characterize in subsurface the drain with less flow (37 m3 /h), besides intermediary flow and electrical resistivity values, attributed to the predominance of areas with accumulation or generation of biogas.

Influence of storage period of pieces in stiffness of pinus elliottii Glulam Beams

This study aimed to investigate the influence of storage time (0, 48 hours) of Pinus elliottii pieces and the tests to obtaining modulus of elasticity (static bending and transversal vibration) in glued laminated timber beams, produced with resorcinol based adhesive and 0.8 MPa compaction pressure. After pieces were properly prepared, part of them was used in immediate three manufacturing glulam beams, tested after adhesive cure, and part stored for 48 hours under a roof with a temperature of 25°C and relative humidity of 60% for subsequent manufacturing and testing three other glulam beams. Results of analysis of variance (ANOVA) revealed that the storage period was significant influence in modulus of elasticity obtained in static bending test (8% reduction from 0 to 48 hours). This not occurred with modulus of elasticity obtained by transversal vibration test (no significant influence). ANOVA results showed equivalence of means in both test procedures. New researches ire needed to better understand the investigated phenomenon, using new wood species, other storage conditions and a great number of samples.

Influence of nonlinear stiffness on the dynamics of a slender elastic beam under torsional oscillations

This study focuses on analysing the effects of nonlinear torsional stiffness on the dynam-ics of a slender elastic beam under torsional oscillations, which can be subject to helical buckling.The helical buckling of an elastic beam confined in a cylinder is relevant to many applications. Someexamples include oil drilling, medical cateters and even the conformation and functioning of DNAmolecules. A recent study showed that the formation of the helical configuration is a result of onlythe torsional load, confirming that there is a different path to helical buckling which is not related tothe sinusoidal buckling, stressing the importance of the geometrical behaviour of the beam. A lowdimensional model of an elastic beam under torsional oscillations is used to analyse its dynamical be-haviour with different stiffness characteristics, which are present before and after the helical buckling.Hardening and softening characteristics are present, as the effects of torsion and bending are coupled.With the use of numerical algorithms applied to nonlinear dynamics, such as bifurcation diagramsand basins of attraction, it is shown that the nonlinear stiffness can shift the bifurcations and inducechanges in the stability of the desirable and undesirable solutions. Therefore, the proper modellingof these stiffness nonlinearities seems to be important for a better understanding of the dynamicalbehaviour of such beams.

Influence of the number of load cycles to obtain the stiffness properties of angico preto (Anadenanthera macrocarpa) wood specie

The tests used to obtain the stiffness properties of wood are made with two loading cycles, as defined by the Brazilian standard ABNT NBR 7190 (Design of Timber Structures). However, the possibility of reducing the number of cycles allows decrease the operating time of the machine, resulting in reduced spending on electricity used during the tests. This research aimed to investigate, with the aid of the analysis of variance (ANOVA), the influence of the use of three load cycles to obtain the modulus of elasticity in compression parallel to grain (Ec0), in tensile parallel to the grain (Et0), in bending (Em) and in compression perpendicular to the grain (Ec90) of Angico Preto (Anadenanthera macrocarpa) wood specie. For the number of cycles and stiffness were manufactured 12 samples, totaling 144 specimens. The results of the ANOVA revealed statistical equivalence between the stiffness properties for both load cycle numbers evaluated, indicating that it is possible to carry out the tests with a single charge cycle, allowing savings in time and energy in the operation of the equipment.

Potent Antiretroviral Therapy for Human Immunodeficiency Virus Infection Increases Aortic Stiffness

Background: Highly active antiretroviral therapy for AIDS is known to increase cardiovascular risk, but the effects of potent antiretroviral agents according to gender are unknown. Objective: The present study evaluated the impact of HIV infection treatment on aortic stiffness according to gender. Methods: From university-affiliated hospitals, we recruited 28 AIDS patients undergoing highly active antiretroviral treatment (HAART), 28 treatment-naive HIV-infected patients, 44 patients with type 2 diabetes, and 30 controls. Aortic stiffness was determined by measuring pulse wave velocity (PWV) using a validated and non-invasive automatic device. Results: The crude mean PWV values and 95% confidence intervals (95% CI) for HAART, diabetics, and controls were 9.77 m/s (95% CI 9.17-10.36),, 9.00 m/s (95% CI 8.37-9.63), 9.90 m/s (95% CI 9.32-10.49), and 9.28 m/s (95% CI 8.61-9.95), respectively, for men (P-value for trend = 0.14), and 9.61 m/s (95% CI 8.56-10.66), 8.45 m/s (95% CI 7.51-9.39), 9.83 (95% CI 9.21-10.44), and 7.79 m/s (95% CI 6.99-8.58), respectively, for women (P-value for trend <0.001). Post-hoc analysis revealed a significant difference between the mean PWV values in the HAART group and controls in women (P-value <0.01). After adjusting for other potential covariates, including systolic blood pressure and diabetes, these results did not change. The findings indicate that the impact of HAART treatment on aortic stiffness was amplified in women with hypertension, dyslipidemia, and metabolic syndrome. Conclusion: Potent anti-retroviral agents used in the treatment of HIV infection increases aortic stiffness, mainly among women with higher cardiovascular risk. (Arq Bras Cardiol 2012;99(6):1100-1107)

Predicting dysthyroid optic neuropathy using computed tomography volumetric analyses of orbital structures

OBJECTIVE: To evaluate the ability of orbital apex crowding volume measurements calculated with multidetector-computed tomography to detect dysthyroid optic neuropathy. METHODS: Ninety-three patients with Graves' orbitopathy were studied prospectively. All of the patients underwent a complete neuro-ophthalmic examination and computed tomography scanning. Volumetric measurements were calculated from axial and coronal contiguous sections using a dedicated workstation. Orbital fat and muscle volume were estimated on the basis of their attenuation values (in Hounsfield units) using measurements from the anterior orbital rim to the optic foramen. Two indexes of orbital muscle crowding were calculated: i) the volumetric crowding index, which is the ratio between soft tissue (mainly extraocular muscles) and orbital fat volume and is based on axial scans of the entire orbit; and ii) the volumetric orbital apex crowding index, which is the ratio between the extraocular muscles and orbital fat volume and is based on coronal scans of the orbital apex. Two groups of orbits (with and without dysthyroid optic neuropathy) were compared. RESULTS: One hundred and two orbits of 61 patients with Graves' orbitopathy met the inclusion criteria and were analyzed. Forty-one orbits were diagnosed with Graves' orbitopathy, and 61 orbits did not have optic neuropathy. The two groups of orbits differed significantly with regard to both of the volumetric indexes (p<0.001). Although both indexes had good discrimination ability, the volumetric orbital apex crowding index yielded the best results with 92% sensitivity, 86% specificity, 81%/94% positive/negative predictive value and 88% accuracy at a cutoff of 4.14. CONCLUSION: This study found that the orbital volumetric crowding index was a more effective predictor of dysthyroid optic neuropathy than previously described computed tomography indexes were.

Bending stiffness evaluation of Teca and Guajara lumber through tests of transverse and longitudinal vibration

The grading of structural lumber besides contributing for increasing the structure's safety, due to the reduction of the material variability, also allows its rational use. Due to the good correlation between strength and bending stiffness, the latter has been used in estimating the mechanical strength of lumber pieces since the 60's. For industrial application, there are equipment and techniques to evaluate the bending stiffness of lumber, through dynamic tests such as the longitudinal vibration technique, also known as stress wave, and the transverse vibration technique. This study investigated the application of these two techniques in the assessment of the modulus of elasticity in bending of Teca beams (Tectona grandis), from reforestation, and of the tropical species Guajara (Micropholis venulosa). The modulus of elasticity estimated by dynamic tests showed good correlation with the modulus measured in the static bending test. Meantime, we observed that the accuracy of the longitudinal vibration technique was significantly reduced in the evaluation of the bending stiffness of Teca pieces due to the knots existing in this species.