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Area and Individual Radiation Monitoring
Published in Arash Darafsheh, Radiation Therapy Dosimetry: A Practical Handbook, 2021
The Fluke Biomedical7 Neutron Survey Meter Model 190N, is based upon the classical Andersson–Braun rem-meter design. A polyethylene cylinder 24 cm long, and 21.6 cm in diameter surrounds the BF3 tube. The tube is filled with 96% enriched 10B. The instrument is available with display in either rem or Sv. According to the manufacturer, the instrument has a dose equivalent range from 0 μSv/h to 0.75 Sv/h, and it can integrate doses from 0 μSv to 10 Sv. It has a gamma rejection up to 500 Roentgens/h for 137Cs. The directionality is less than 20% in orthogonal directions.
Epidemiology
Published in Samuel C. Morris, Cancer Risk Assessment, 2020
Study designs can then be described in terms of their directionality and their timing (Kleinbaum et al., 1982). Directionality refers to the temporal relationship between observation of exposure and disease incidence. A prospective study, in which exposure is measured first and the population is followed to observe disease incidence, has forward directionality. A case-control study, in which the disease is observed first, and exposures are then investigated through individual histories, has backward directionality. Some would use the terms prospective and retrospective to describe directionality, instead of forward and backward. In reading the report of a study, it is important to look behind the terms used and understand the nature of the design. A study may also have nondirection-ality, in which exposure and disease are observed simultaneously. A cross-sectional study, for example, in which cancer mortality rates and concentrations of carcinogens in air are determined in several different cities and correlations then analyzed, would be nondirectional. Both exposure and disease are observed at a single point or interval in time. Especially for a cancer study, of course, there is an implicit assumption in such a cross-sectional study that the current exposure is an indication of past exposure, since current cancer incidence could not have been caused by current exposure levels.
Why does it matter? Medical engagement and organisational performance
Published in Peter Spurgeon, John Clark, Chris Ham, Sir Bruce Keogh, Medical Leadership: From the Dark Side to Centre Stage, 2017
Peter Spurgeon, John Clark, Chris Ham, Sir Bruce Keogh
The essential hypothesis of the engagement model is that higher levels of engagement generate a greater frequency of positive affect, such as satisfaction and commitment, and this in turn flows through to enhanced work performance. It is clearly a multifaceted concept, and some aspects of directionality, i.e. which aspects cause what in different circumstances and in different individuals, may be difficult to pin down. However, research has sought to explore the key aspects of what causes higher levels of engagement and what might be the consequences (outcomes) for the organisation of achieving higher levels of engagement.
Reassessing the Ethics of Molecular HIV Surveillance in the Era of Cluster Detection and Response: Toward HIV Data Justice
Published in The American Journal of Bioethics, 2020
Stephen Molldrem, Anthony K J Smith
The utilization of phylogenetic analyses of HIV genetic sequence data in criminal proceedings where HIV transmission is alleged is a recognized problem (Barré-Sinoussi et al. 2018; Galletly et al. 2019; UNAIDS 2013). A key issue in criminal contexts is whether phylogenetic analysis can be utilized to discern directionality of transmission (i.e. to prove that person A transmitted HIV to person B). A consensus across the ethical literature is that HIV phylogenetic analysis cannot be used to infer directionality (Coltart et al. 2018; Mutenherwa et al. 2019). However, as we explore in case two, some practitioners argue that directionality can be inferred. Similarly, Mutenherwa et al.’s (2019) participants were concerned about MHS being used to identify “high HIV transmitters” and marginalized subpopulations. As we explore in case three, this has occurred, and some researchers encourage the use of phylogenetic software for “[f]inding likely transmitters in a large population cohort” (Wymant et al. 2018, 728). From an ethical and methodological perspective, the distinction between whether directionality cannot or should not be inferred using molecular data is not clear.
Clinical features of patients with high and normal CSFP in venous pulsating tinnitus
Published in Acta Oto-Laryngologica, 2020
The flow of cerebrospinal fluid has a certain directionality. The collateral plexus of the two lateral ventricles is the most abundant and produces most of the cerebrospinal fluid. This cerebrospinal fluid flows into the third ventricle through the interventricular pores and then flows into the fourth ventricle through the midbrain aqueduct. The cerebrospinal fluid produced by the choroid plexus of each ventricle converges in the fourth ventricle and flows into the subarachnoid space of the brain and spinal cord through the median and lateral foramina of the fourth ventricle. Finally, the cerebrospinal fluid infiltrates into the superior sagittal sinus through the arachnoid granules beside the sagittal sinus before returning to the venous system [16–18]. Under normal circumstances, there are arachnoid granules in the cross-sectional area of the transverse sinus and sigmoid sinus on the dominant drainage side. When inflammation occurs, it may cause adhesion and narrowing of the vascular lumen, and hemodynamic changes occur when blood flows through the stenosis. Watane et al also found a correlation between arachnoid granules and BIH [19]. Most MRA and MRV results in this study showed superior drainage of the sigmoid sinus on the tinnitus side. We speculate that high CSFP may impact the hemodynamics of intracranial veins, and abnormal intracranial veins may also affect CSFP; that is to say, intracranial veins and CSFP interact through the important medium – arachnoid granules, and thereby participate in the occurrence and development of vascular tinnitus.
Cannabis use among U.S. adolescents in the era of marijuana legalization: a review of changing use patterns, comorbidity, and health correlates
Published in International Review of Psychiatry, 2020
Christopher J. Hammond, Aldorian Chaney, Brian Hendrickson, Pravesh Sharma
Cross-sectional and longitudinal studies show that compared to controls adolescent and young adult cannabis users have increased anxiety, anxiety sensitivity, and panic attacks, and increased rates of co-occurring anxiety disorders including social anxiety disorder, panic disorder, and post-traumatic stress disorders (PTSD) (Buckner et al., 2017; Cornelius et al., 2010; Zvolensky et al., 2006). A recent meta-analysis in adults suggests a modest relationship between cannabis use and anxiety (Kedzior & Laeber, 2014). Findings regarding the directionality of these associations are mixed. Adverse childhood experiences and chronic stress generally precede the onset of cannabis use and increase the risk for early-onset cannabis use and progression to CUD by young adulthood (Buckner et al., 2012; Hyman & Sinha, 2009). Some longitudinal studies have shown a long-term relationship between adolescent-cannabis use and increased risk for anxiety disorders in adulthood (Degenhardt et al., 2013; Fergusson & Horwood, 1997), while others have shown no association (Buckner et al., 2012) or the inverse association (Buckner et al., 2008). Adolescent cannabis use and CUDs have been prospectively associated with increased odds for panic attacks and disorders, but some of the variances in this relationship may be related to co-occurring tobacco use (Zvolensky et al., 2008). More recently, a 2019 meta-analysis of longitudinal studies failed to find an association between adolescent cannabis use and later anxiety disorders (Gobbi et al., 2019). Future research is needed in this area, especially given that many states have added anxiety disorders and PTSD as ‘indicated conditions’ for medical marijuana (Mitchell, 2019).