The Contributory Effect of Latency on the Quality of Voice Transmitted over the Internet

Deployment of Voice over Internet Protocol (VoIP) is rapidly growing worldwide due to the new services it provides and cost savings derived from using a converged IP network. However, voice quality is affected by bandwidth, delay, latency, jitter, packet loss e.t.c. Latency is the dominant factor that degrades quality of voice transfer. There is therefore strong need for a study on the effect of Latency with the view to improving Quality of Voice (QoV) in VoIP network. In this work, Poisson probability theorem, Markov Chain, Probability distribution theorems and Network performance metric were used to study the effect of latency on QoS in VoIP network. This is achieved by considering the effect of latency resulting from several components between two points in multiple networks. The NetQoS Latency Calculator, Net-Cracker Professional® for Modeling and Matlab/Simulink® for simulating network were tools used and the results obtained compare favourably well with theoretical facts

A Comparison of Airway Dimensions among Different Skeletal Craniofacial Patterns

Background and Objectives: Much attention has been given to the association of craniofacial skeletal morphology, upper airway dimension, and respiratory function with patients suffering from obstructive sleep apnea. However, much of the information gathered on the aforementioned has been established with the use of 2-Dimensional lateral cephalometry. The objective of this study was to investigate upper airway dimensions among different skeletal patterns using cone-beam computed tomography (CBCT). Methods: A sample of 279 patients who seught orthodontic treatment at the University of Nevada Las Vegas School of Dentistry Department of Orthodontics was included in this study. Pre-treatment multi-slice CBCT scans of these subjects were divided into three sagittal groups: Class I subjects with an ANB angle 0° to 5°, Class II subjects with an ANB angle \u3e 5°, and Class III subjects with an ANB angle \u3c 0°. The CBCT scans were also divided into three vertical groups: normodivergent subjects with a mandibular plane angle 22° to 30°, hyperdivergent subjects with a mandibular plane angle \u3e 30°, and hypodivergent subjects with a mandibular plane angle\u3c 22°. The sagittal and vertical groups were analyzed individually (6 groups) and together (9 groups) to determine if the various combination of skeletal patterns has any effects on airway volume, minimum cross sectional area (CSA), and airway shape. CBCT scans were analyzed using Dolphin Imaging 10.5 Premium and Anatomage In VivoDental(TM) software version 5.1. Data were analyzed using ANOV A, Tukey-Kramer, Student t test, and Wilcoxon/Kruskal-Wallis tests. Results: Significant differences were found among the sagittal groups for airway volume and minimum CSA, p \u3c .05. Class III subjects were found to have the largest airway volume and minimum CSA while Class II subjects were found to have the smallest airway volume and minimum CSA. Minimum CSA was found to have an increasing function of airway volume. CSA increased by 10.23 mm2 for every cc increase in airway volume. No significant differences were found among the vertical groups. However, Class II subjects with hyperdivergent skeletal pattern were found to have the smallest airway volume and minimum CSA. No associations were found between the airway shapes and airway volume when evaluating sagittal and/or vertical skeletal patterns. However, wide airway shapes were shown to have the largest airway volume while long airway shapes were shown to have the smallest airways. Conclusions: Airway dimensions can be affected by craniofacial skeletal pattern. Patients with Class II hyperdivergent skeletal pattern may be more prone to obstructive sleep apnea problems

Radiation Exposure of Patients by Cone Beam CT during Endobronchial Navigation - A Phantom Study

Rationale: Cone Beam Computed Tomography imaging has become increasingly important in many fields of interventional therapies. Objective: Lung navigation study which is an uncommon soft tissue approach. Methods: As no effective organ radiation dose levels were available for this kind of Cone Beam Computed Tomography application we simulated in our DynaCT (Siemens AG, Forchheim, Germany) suite 2 measurements including 3D acquisition and again for 3D acquisition and 4 endobronchial navigation maneuvers under fluoroscopy towards a nodule after the 8th segmentation in the right upper lobe over a total period of 20 minutes (min). These figures reflect the average complexity and time in our experience. We hereby describe the first time the exact protocol of lung navigation by a Cone Beam Computed Tomography approach. Measurement: The hereby first time measured body radiation doses in that approach showed very promising numbers between 0,98-1,15mSv giving specific lung radiation doses of 0,42-0,38 mSv. Main results: These figures are comparable or even better to other lung navigation systems. Cone Beam Computed Tomography offers some unique features for lung interventionists as a realtime 1-step navigation system in an open structure feasible for endobronchial and transcutaneous approach. Conclusions: Due to this low level of radiation exposure Cone Beam Computed Tomography is expected to attract interventionists interested in using and guiding endobronchial or transcutaneous ablative procedures to peripheral endobronchial and other lung lesions

Do We Truly Sacrifice Truth for Simplicity: Comparing Complete Individual Randomization and Semi-Randomized Approaches to Survey Administration

Human-computer interaction researchers have long used survey methodologies. However, debate remains about the potential for participants to provide biased responses to subsequent items based on previously viewed items. In this research, we investigate the effects of survey item ordering that researchers have not studied previously. Grounded in previous exploratory item-ordering studies using an HCI online survey, we investigate bias in more detail. In addition, we use an adult sample population so that we can extend our results more broadly as compared to previous research. We employed two distinct randomizing survey approaches: 1) complete item randomization for each respondent (random), which presents items to each respondent in a completely randomized order; and 2) partially individualized item randomization (grouped), which presents constructs in the same order in a survey but randomizes items in each construct for each respondent. Our results suggest researchers should use fully randomized survey instruments in HCI research whenever possible since grouped ordering of any kind increases bias and statistical inflation, which can influence results’ veracity. Additionally, we did not appear to find any significant increase in the participants’ frustration or fatigue to be associated with the random treatment

A study of residual Cesium 137 contamination in southwestern Utah soil following the nuclear weapons tests at the Nevada Test Site in the 1950's and 1960's

The Nevada Test Site (NTS) was the location for at least 100 above ground Nuclear Weapons tests during the 1950's and early 1960's. Radioactive fallout from these tests spread to many areas north and west of the NTS. According to estimates from the NCI and DOE, Washington County, Utah was one of the areas which received some of the highest levels of radioactive contamination from Nuclear Fallout. Cesium 137, a byproduct of Nuclear Fission was one of the nuclides deposited during this fallout period. Cesium 137 has a half life of 30 years and relatively high photon energy so it is easily detected and theoretically would still be present in the soil if it was originally deposited there. A study was conducted using soil samples from the Washington County area to determine if Cesium 137 still exists in the area in detectable amounts. 102 soil samples were collected and analyzed. Only one of the 102 soil samples did not have detectable amounts of Cesium contained within it. Several of the samples contained levels substantially higher than earlier estimates would have predicted. This leads us to conclude that doses to the public from the testing could also have been higher than earlier thought. The area immediately around the community of Enterprise Utah contained the highest contamination readings of the locations we researched. Iron County, Northeast of St George, also had surprisingly high readings considering that the studies we researched stated that Iron County's contamination density was estimated to be lower than most of the areas in Washington County

Protocol variation analysis of whole brain CT perfusion in acute ischemic stroke

Computed tomography perfusion (CTP) analysis is a rapidly advancing imaging modality that is improving diagnosis of brain abnormalities in patients suffering from hemorrhagic or ischemic stroke, traumatic brain injury, vascular occlusion and numerous other conditions. Through the advancements of computed tomography (CT) imaging, including the introduction of the 320-detector row CT with a 16 centimeter range in the z-axis enabling whole brain CTP, perfusion analysis now has a significantly increased clinical utility that is useful for both diagnosis and treatment of central nervous system (CNS) conditions. This study focuses on the procedural and analytical approach to the diagnostic evaluation of patients suffering from acute ischemic stroke (AIS). Through the automatic, manual ipsilateral, and manual contralateral selection of the arterial input function (AIF) and venous input function (VIF), along with the interchangeable combinations using singular value decomposition (SVD) and singular value decomposition plus (SVD+) deconvolution algorithms, CTP parametric maps are compared and analyzed for similarities and differences between each selection method. In particular, the region of interest (ROI) placements on the axial views of the perfusion maps are compared with the values derived by the SVD+ and SVD deconvolution algorithms for each AIF/VIF selection. These differences and product CTP map manipulations allow for outcomeassessments that prove which approach provides the best clinical accuracy and reproducibility for evaluating or diagnosing acute ischemic stroke with computed tomography perfusion. In this study of protocol variation analysis, SVD+ produced more consistent CTP values with less variation than the SVD deconvolution algorithm. With the use of the SVD+ deconvolution algorithm, the most consistent results were produced with the AIF manually placed in the contralateral M1 segment of the middle cerebral artery (MCA) and the venous input function (VIF) placed in the posterior portion of the superior sagittal sinus (SSS)