Effects of a Demand-Valve SCUBA Regulator on Cardiorespiratory Response During Submaximal Exercise Under Normobaric Conditions: A Preliminary Investigation

SCUBA diving fatalities are often related to cardiac events triggered by stress linked to equipment. The purpose of this investigation was to examine the effects of a SCUBA regulator on cardiorespiratory exercise at a submaximal workload. Ten participants (mean = 21.5 yrs; s.d. = 1.16) completed two submaximal exercise tests at 1 ATA; one while breathing normally and a second while breathing directly from a demand valve SCUBA regulator. Total time to test completion (TOT), heart rate (HR), blood pressure (BP), rating of perceived exertion (RPE), and arterial oxygen levels were all assessed. No significant differences between conditions were found for measures of TOT, heart rate, blood pressure, RPE, and arterial oxygen measures. Statistical analysis suggested that use of a SCUBA regulator itself did not affect exercise tolerance or increase cardiorespiratory stress at submaximal workloads. Several anecdotal observations in HR, BP, TOT, and RPE responses suggested further research is warranted

Effect of In-water SCUBA Diving Activities on Response Time in Recreational Divers

The purpose of this study was to examine the relationship between the performance of in-water scuba diving training activities and simple motor response time. Twenty-four students enrolled in a scuba course had their motor response times measured before and after a one hour training session. Pre- and post-dive response times were measured using an iPad application. Additionally, students were asked to complete a dive history questionnaire to determine their diving experience and health history. Statistical analysis indicated a significant training effect on response time in the recreational scuba divers F (1.00, 23.00) p =.033. The results of this study suggest that basic in-water scuba training activities may improve one\u27s ability to elicit quicker movement responses and lead to faster cognitive processing

Scuba diving and the stress response: considerations and recommendations for professional and recreational divers

Scuba diving is an activity that people engage in both for recreational purposes as well as having professional,commercial, and military applications. Scuba diving has often been considered a high-risk activitybut, overall, scuba diving has been shown to be a safe activity when divers participate within their experiential,physical, and psychological limits. However, increased physical and psychological stress can quicklyarise during diving activities due to unexpected events and situations and may lead to the onset of panicin an unprepared diver. Dive safety is dependent on the ability of a diver to understand the primary signsof stress and panic and attempt to minimise their potential impacts on the immediate situation. The purposeof this review is to examine the stress response in divers, illustrate the role that panic plays in potentialdiving accidents and fatalities, and provide recommendations to both help understand and manage stressand panic in the diving community in an effort to further increase the overall safety of scuba diving acrossall applications

Expanding the role of 3-O sulfated heparan sulfate in herpes simplex virus type-1 entry

AbstractHeparan sulfate (HS) proteoglycans are commonly exploited by multiple viruses for initial attachment to host cells. Herpes simplex virus-1 (HSV-1) is unique because it can use HS for both attachment and penetration, provided specific binding sites for HSV-1 envelope glycoprotein gD are present. The interaction with gD is mediated by specific HS moieties or 3-O sulfated HS (3-OS HS), which are generated by all but one of the seven isoforms of 3-O sulfotransferases (3-OSTs). Here we demonstrate that several common experimental cell lines express unique sets of 3-OST isoforms. While the isoforms 3-OST-3, -5 and -6 were most commonly expressed, isoforms 3-OST-2 and -4 were undetectable in the cell lines examined. Since most cell lines expressed multiple 3-OST isoforms, we addressed the significance of 3-OS HS in HSV-1 entry by down-regulating 2-O-sulfation, a prerequisite for 3-OS HS formation, by knocking down 2-OST expression by RNA interference (RNAi). 2-OST knockdown was verified by reverse-transcriptase PCR and Western blot analysis, while 3-OS HS knockdown was verified by immunofluorescence. Cells showed a significant decrease in viral entry, suggesting an important role for 3-OS HS. Implicating 3-OS HS further, cells knocked down for 2-OST expression also demonstrated decreased cell–cell fusion when cocultivated with effector cells transfected with HSV-1 glycoproteins. Our findings suggest that 3-OS HS may play an important role in HSV-1 entry into many different cell lines

Psychometric Network Analysis of the Hungarian WAIS

The positive manifold—the finding that cognitive ability measures demonstrate positive correlations with one another—has led to models of intelligence that include a general cognitive ability or general intelligence (g). This view has been reinforced using factor analysis and reflective, higher-order latent variable models. However, a new theory of intelligence, Process Overlap Theory (POT), posits that g is not a psychological attribute but an index of cognitive abilities that results from an interconnected network of cognitive processes. These competing theories of intelligence are compared using two different statistical modeling techniques: (a) latent variable modeling and (b) psychometric network analysis. Network models display partial correlations between pairs of observed variables that demonstrate direct relationships among observations. Secondary data analysis was conducted using the Hungarian Wechsler Adult Intelligence Scale Fourth Edition (H-WAIS-IV). The underlying structure of the H-WAIS-IV was first assessed using confirmatory factor analysis assuming a reflective, higher-order model and then reanalyzed using psychometric network analysis. The compatibility (or lack thereof) of these theoretical accounts of intelligence with the data are discussed

Cardiac myocyte-specific knock-out of calcium-independent phospholipase A2γ (iPLA2γ) decreases oxidized fatty acids during ischemia/reperfusion and reduces infarct size

Calcium-independent phospholipase A(2)γ (iPLA(2)γ) is a mitochondrial enzyme that produces lipid second messengers that facilitate opening of the mitochondrial permeability transition pore (mPTP) and contribute to the production of oxidized fatty acids in myocardium. To specifically identify the roles of iPLA(2)γ in cardiac myocytes, we generated cardiac myocyte-specific iPLA(2)γ knock-out (CMiPLA(2)γKO) mice by removing the exon encoding the active site serine (Ser-477). Hearts of CMiPLA(2)γKO mice exhibited normal hemodynamic function, glycerophospholipid molecular species composition, and normal rates of mitochondrial respiration and ATP production. In contrast, CMiPLA(2)γKO mice demonstrated attenuated Ca(2+)-induced mPTP opening that could be rapidly restored by the addition of palmitate and substantially reduced production of oxidized polyunsaturated fatty acids (PUFAs). Furthermore, myocardial ischemia/reperfusion (I/R) in CMiPLA(2)γKO mice (30 min of ischemia followed by 30 min of reperfusion in vivo) dramatically decreased oxidized fatty acid production in the ischemic border zones. Moreover, CMiPLA(2)γKO mice subjected to 30 min of ischemia followed by 24 h of reperfusion in vivo developed substantially less cardiac necrosis in the area-at-risk in comparison with their WT littermates. Furthermore, we found that membrane depolarization in murine heart mitochondria was sensitized to Ca(2+) by the presence of oxidized PUFAs. Because mitochondrial membrane depolarization and calcium are known to activate iPLA(2)γ, these results are consistent with salvage of myocardium after I/R by iPLA(2)γ loss of function through decreasing mPTP opening, diminishing production of proinflammatory oxidized fatty acids, and attenuating the deleterious effects of abrupt increases in calcium ion on membrane potential during reperfusion

Photometric Redshifts of Submillimeter Galaxies

We use the photometric redshift method of Chakrabarti & McKee (2008) to infer photometric redshifts of submillimeter galaxies with far-IR (FIR) $\it{Herschel}$ data obtained as part of the PACS Evolutionary Probe (PEP) program. For the sample with spectroscopic redshifts, we demonstrate the validity of this method over a large range of redshifts ( 4 \ga z \ga 0.3) and luminosities, finding an average accuracy in $(1+z_{\rm phot})/(1+z_{\rm spec})$ of 10%. Thus, this method is more accurate than other FIR photometric redshift methods. This method is different from typical FIR photometric methods in deriving redshifts from the light-to-gas mass ($L/M$) ratio of infrared-bright galaxies inferred from the FIR spectral energy distribution (SED), rather than dust temperatures. Once the redshift is derived, we can determine physical properties of infrared bright galaxies, including the temperature variation within the dust envelope, luminosity, mass, and surface density. We use data from the GOODS-S field to calculate the star formation rate density (SFRD) of sub-mm bright sources detected by AzTEC and PACS. The AzTEC-PACS sources, which have a threshold 850 \micron flux \ga 5 \rm mJy, contribute 15% of the SFRD from all ULIRGs (L_{\rm IR} \ga 10^{12} L_{\odot}), and 3% of the total SFRD at $z \sim 2$.Comment: 7 pages, 2 figures, submitted to Ap

Laboratory measurements of high-frequency, acoustic broadband backscattering from sea ice and crude oil

Recent decreases in summer sea ice cover are spurring interest in hydrocarbon extraction and shipping in Arctic waters, increasing the risk of an oil spill in ice covered waters. With advances in unmanned vehicle operation, there is an interest in identifying techniques for remote, underwater detection of oil spills from below. High-frequency (200–565 kHz), broadband acoustic scattering data demonstrate that oil can be detected and quantified under laboratory grown sea ice and may be of use in natural settings. A simple scattering model based on the reflection coefficients from the interfaces agrees well with the data