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Innovations in Noninvasive Instrumentation and Measurements
Published in Robert B. Northrop, Non-Invasive Instrumentation and Measurement in Medical Diagnosis, 2017
PCR has several important medical applications. The DNA to be analyzed is obtained from cells in a blood drop, from a cheek swab, a hair follicle, or from a minimally invasive tissue biopsy. Some of the medical applications include, but are not limited to PCR testing of a person's genome for heritable genetic diseases is one important application. Prospective parents’ DNA can be tested for being carriers of a recessive gene or genes that might be expressed in their children.PCR can be used as part of a sensitive test for tissue typing, critical information for organ transplantation or donation.Many forms of cancer involve base alterations to oncogenes. By using PCR-based tests to study these mutations, therapy regimens can sometimes be individually customized to a patient.With highly infective viruses, PCR tests have been developed that can detect as little as one viral genome among the DNA of over 50,000 host cells (Kwok et al. 1987). (Note that HIV is a retrovirus whose ssRNA genome is copied into its host cell's DNA.)PCR-based tests allow the detection of small numbers of hard-to-culture disease organisms (both dead and alive) in body fluids. Mycobacterium tuberculosis divides once every 15–20 hours under ideal conditions, which is very slow compared to other bacteria. The M. tuberculosis genome was sequenced in 1998.PCR testing is used to track the mutations of a disease pathogen in time, and identify new, virulent subtypes that emerge in an epidemic, or alternately, evolve into more benign strains.
Influence of facial hair length, coarseness, and areal density on seal leakage of a tight-fitting half-face respirator
Published in Journal of Occupational and Environmental Hygiene, 2018
Evan L. Floyd, J. Blake Henry, David L. Johnson
Cheek and chin areal beard density, as hairs/cm2, for each subject were measured as described above and the average number of hairs/cm2 in the cheek and chin areas are shown in Figure 3. A paired sample t-test indicated cheek and chin areal densities to be significantly different (p = 0.0015), with the ratio of chin to cheek density being >1 for 16 of the 19 subjects (median 1.38, range 0.73–4.92, interquartile range 1.09–1.97). However, the correlation between average cheek and chin areal densities was weak (Pearson Correlation Coefficient, r = 0.264); therefore, cheek and chin areal densities were averaged for each subject. For the entire test group, the mean and median were quite close (40.1 vs. 41.0 hairs/cm2, respectively) with a range of 19.0–66.0 hairs/cm2 across subjects.
Acute Pain, Neck Extensor Endurance, and Kinematic Changes Resulting from Sustained Neck Flexion during Smartphone Use
Published in IISE Transactions on Occupational Ergonomics and Human Factors, 2022
Kaitlin M. Gallagher, John Jefferson, Ashton Human, Caleb Burruss
A motion capture system (Qualisys AB, Gotenberg, Sweden) was used to assess head and trunk positions during the 30-minutes of smartphone use. Individual reflective markers (Figure 1) were placed bilaterally on the acromion, anterior superior iliac spine, zygomatic bone (cheek), and forehead. Two rigid marker clusters with five markers each were placed on a headband and the thorax. Marker data were sampled at 50 Hz. A static calibration trial was taken for the kinematic model while the participant sat in the banquet chair looking straight ahead. The individual markers were then removed. During data collection, the head and trunk positions were defined by their respective marker clusters (Figure 1).
Customized design and 3D printing of face seal for an N95 filtering facepiece respirator
Published in Journal of Occupational and Environmental Hygiene, 2018
Mang Cai, Hui Li, Shengnan Shen, Yu Wang, Quan Yang
In the case of the smiling expression (Figure 9b), contact pressures at the five key locations varied greatly, compared with the neutral expression. For example, contact pressures at the nasal bridge (location A) decreased to 0.015 MPa both with and without the face seal. On the contrary, contact pressures at the top of the cheek (location B), bottom of cheek (location D) and chin (location E) increased both with and without the face seal. On the other hand, it should be noted that in the case of the smiling expression, contact pressures at middle of cheek (locations C) and bottom of cheek (location D) while using the face seal were greater compared to when the face seal was not used.