Liquid acrobatics

We experiment with injecting a continuous stream of gas into a shallow liquid, similar to how one might blow into a straw placed at the bottom of a near-empty drink. By varying the angle of the straw (here a metal needle), we observe a variety of dynamics, which we film using a high-speed camera. Most noteworthy is an intermediate regime in which cyclical jets erupt from the air-liquid interface and breakup into air-born droplets. These droplets trace out a parabolic trajectory and bounce on the air-liquid interface before eventually coalescing. The shape of each jet, as well as the time between jets, is remarkably similar and leads to droplets with nearly identical trajectories. The following article accompanies the linked fluid dynamics video submitted to the Gallery of Fluid Motion in 2008.Comment: Accompanies video submission to APS DFD 2008 Gallery of Fluid Motion, low http://ecommons.library.cornell.edu/bitstream/1813/11469/3/Bird_DFD2008_mpeg1.mpg , and high resolution http://ecommons.library.cornell.edu/bitstream/1813/11469/2/Bird_DFD2008_mpeg2.mp

The Effect of Bromide on Trihalomethane Formation

A study was conducted to examine the effect of bromide on the formation and distribution of trihalomethanes in drinking water. Chlorination experiments were made under controlled laboratory conditions of bromide level, chlorine dose, pH, ionic strength, temperature, and organic precursor concentration. Two types of raw waters were chlorinated: pure humic acid solutions and filtered Tennessee River water. Resulting trihalomethane formations were monitored over 96 hour reaction periods. The results indicated that bromide can be an important factor in THM formation. An increase in TTHM yield and a shift toward more brominated THMs was observed for an increase in initial bromide level. A decrease in the effect of chlorine dose on TTHM yield and distribution was noticed with an increase in initial bromide level. For a given level of bromide, a decrease in humic acid level was found to be associated with an increase in the amount of bromine THMs relative to the amount of chlorine THMs. Ionic strength was found to have no influence on TTHM yield or distribution for the levels of bromide examined. The effect of pH on TTHM yield was observed to be enhanced at higher levels of bromide. The temperature dependence on THM formation was found to be strongly influenced by the bromide level. The temperature dependence of CHC13 formation was found to decrease with an increase in bromide. The temperature dependence of CHC1Br2 formation was found to be greatest at a level of bromide corresponding to its predominance in the TTHM distribution. The temperature dependence of CHC1Br2 formation was found to be greatest at a level of bromide corresponding to its predominance in the TTHM distribution. The temperature dependence of CHBr3 formation was found to increase with an increase in bromide level. Similar bromide and temperature effects were observed with the chlorinations of Tennessee River water. In general, a first order computer simulation of THM formation did not give a good fit

International low back pain guidelines: A comparison of two research based models of care for the management of acute low back pain.

Evidence based guidelines for the management of acute low back pain (ALBP) have been formulated by numerous countries. There are discrepancies between guidelines regarding physiotherapy treatment. The aim of this study was to compare two research based models derived from international LBP guidelines. A single-blind randomised controlled trial was undertaken in a physiotherapy outpatients department. Subjects with ALBP were randomly allocated to an ‘assess/advise/treat’ group (n = 50) or an ‘assess/advise/wait’ group (n = 52). The primary outcome measure was the Roland and Morris Disability Questionnaire (RMDQ). Secondary outcome measures of pain (VAS, usual pain intensity) depressive symptoms (MZSRDS) somatic distress (MSPQ) anxiety (STAIS) quality of life (SF36) and general health (EuroQol) were also obtained. Outcomes were assessed at 6-weeks, 3-months and 6-months. At 6-weeks subjects in the assess/advise/treat group demonstrated less LBP related disability (p = 0.02) and depressive symptoms (p = 0.01), as well as better general health (p = 0.006, p = 0.05), vitality (p \u3c 0.001), social functioning (p = 0.004) and mental health (p = 0.002). At long-term assessment (3 and 6 months) subjects in the assess/advise/treat group were less distressed (p = 0.004), anxious (p = 0.01) and had fewer depressive symptoms (p = 0.001), as well as reporting better general health (p = 0.009, p = 0.05), emotional role (p = 0.03) and mental health (p = 0.04). Active physiotherapy produces better short-term outcomes than advice. Delaying treatment has no long-term consequences on pain or disability, but affects the development of psychosocial features

Optimising physiotherapy care for acute low back pain – identifying non-responders to treatment

Recent evidence suggests that positive effects of physiotherapy for acute low back pain patients can be achieved if treatment is delivered early enough. However it is clear that not all patients treated with physiotherapy are likely to report equally positive outcomes from their treatment. The identification of clinical characteristics of those patients who do less well will help refine models of care for acute low back pain. Aim: To identify non-responders to early active physiotherapy. Method: A secondary analysis was conducted on the data from a recently published randomised controlled trial of early physiotherapy for acute low back pain. All patients were randomised into two groups: immediate physiotherapy or advice and wait list and completed a series of physical, psychological and pain measures at baseline and again at six weeks. Multivariate statistical analysis was conducted to identify which patient baseline characteristics were associated with unsuccessful outcomes at the six week follow up. Control group comparisons permitted only those relationships associated with the intervention to be described. Results: Data analysis indicated that subgroups of patients who responded poorly to their physiotherapy treatment could be identified by a priori knowledge of their pain, mental health and physical function (p\u3c0.05). Conclusions: The results of the current analysis suggest that there are identifiable subgroups of patients who respond less well to physiotherapy treatment. Attention to these patient characteristics needs to be included in models of care for acute low back pain so that effects of therapy for all patients can be optimised

Empirical constraints on the nucleosynthesis of nitrogen

We derive empirical constraints on the nucleosynthetic yields of nitrogen by incorporating N enrichment into our previously developed and empirically tuned multizone galactic chemical evolution model. We adopt a metallicity-independent (‘primary’) N yield from massive stars and a metallicity-dependent (‘secondary’) N yield from AGB stars. In our model, galactic radial zones do not evolve along the observed [N/O]–[O/H] relation, but first increase in [O/H] at roughly constant [N/O], then move upward in [N/O] via secondary N production. By t ≈ 5 Gyr, the model approaches an equilibrium [N/O]–[O/H] relation, which traces the radial oxygen gradient. Reproducing the [N/O]–[O/H] trend observed in extragalactic systems constrains the ratio of IMF-averaged N yields to the IMF-averaged O yield of core-collapse supernovae. We find good agreement if we adopt |$y_\text{N}^\text{CC}/y_\text{O}^\text{CC}=0.024$| and |$y_\text{N}^\text{AGB}/y_\text{O}^\text{CC} = 0.062(Z/Z_\odot)$|⁠. For the theoretical AGB yields we consider, simple stellar populations release half their N after only ∼250 Myr. Our model reproduces the [N/O]–[O/H] relation found for Milky Way stars in the APOGEE survey, and it reproduces (though imperfectly) the trends of stellar [N/O] with age and [O/Fe]. The metallicity-dependent yield plays the dominant role in shaping the gas-phase [N/O]–[O/H] relation, but the AGB time-delay is required to match the stellar age and [O/Fe] trends. If we add ∼40 per cent oscillations to the star formation rate, the model reproduces the scatter in the gas phase [N/O]–[O/H] relation observed in external galaxies by MaNGA. We discuss implications of our results for theoretical models of N production by massive stars and AGB stars

The major human and mouse granzymes are structurally and functionally divergent

Approximately 2% of mammalian genes encode proteases. Comparative genomics reveals that those involved in immunity and reproduction show the most interspecies diversity and evidence of positive selection during evolution. This is particularly true of granzymes, the cytotoxic proteases of natural killer cells and CD8+ T cells. There are 5 granzyme genes in humans and 10 in mice, and it is suggested that granzymes evolve to meet species-specific immune challenge through gene duplication and more subtle alterations to substrate specificity. We show that mouse and human granzyme B have distinct structural and functional characteristics. Specifically, mouse granzyme B is 30 times less cytotoxic than human granzyme B and does not require Bid for killing but regains cytotoxicity on engineering of its active site cleft. We also show that mouse granzyme A is considerably more cytotoxic than human granzyme A. These results demonstrate that even “orthologous” granzymes have species-specific functions, having evolved in distinct environments that pose different challenges

Calcium Tartrate Tetrahydrate, Case Report of a Novel Human Kidney Stone

Background: Calcium tartrate tetrahydrate has been reported as the main mineral in urinary stones in rats that have significant tartrate in their diet, but in humans, there has been only one mention of calcium tartrate stones in the form of bladder stone, and that case was in Africa., Case Presentation: Patient is a 34-year-old Caucasian male who presented with typical symptoms of nephrolithiasis. CT abd/pelvis (renal stone protocol) revealed a 2 cm nonobstructing stone of the right renal pelvis. Patient underwent an uncomplicated right percutaneous nephrolithotomy and was noted to be stone free after surgery. Stone analysis was difficult with regard to determining composition, but was finally identified as calcium tartrate tetrahydrate., Conclusion: This was an unusual case, as this is the first recorded case of a calcium tartrate tetrahydrate outside of Africa. This type of stone had only been mainly described in rat models with dl-bitartrate in their diet. Our patient was an otherwise healthy, relatively muscular individual with no obvious source for this stone other than a vitamin and amino acid supplement that he takes regularly that contains l-carnitine (as tartrate) and choline (as bitartrate and citrate). The prevalence of this stone type is presently unknown, as stone analysis laboratories have not had the ability to recognize it. Although a connection between the supplement and stone formation is conjecture at this time, we believe this necessitates further investigation

Gaussian Kinetic Model for Granular Gases

A kinetic model for the Boltzmann equation is proposed and explored as a practical means to investigate the properties of a dilute granular gas. It is shown that all spatially homogeneous initial distributions approach a universal "homogeneous cooling solution" after a few collisions. The homogeneous cooling solution (HCS) is studied in some detail and the exact solution is compared with known results for the hard sphere Boltzmann equation. It is shown that all qualitative features of the HCS, including the nature of over population at large velocities, are reproduced semi-quantitatively by the kinetic model. It is also shown that all the transport coefficients are in excellent agreement with those from the Boltzmann equation. Also, the model is specialized to one having a velocity independent collision frequency and the resulting HCS and transport coefficients are compared to known results for the Maxwell Model. The potential of the model for the study of more complex spatially inhomogeneous states is discussed.Comment: to be submitted to Phys. Rev.

Uncovering a Novel Stone in 27 Patients: Calcium Tartrate Tetrahydrate

Objective To further analyze calcium tartrate tetrahydrate stones after a recent case report described this novel stone. Prior to this, there was only one previously reported occurrence of this stone in a human. This unusual stone composition is not tested for routinely. True prevalence and possible causes of this stone are unknown. Materials/Methods During the previous case report, micro-CT and Fourier-transform infrared spectroscopy were used to identify a calcium tartrate tetrahydrate stone. This information was applied to urinary stones with previously unidentified compositions in the Mayo Metals laboratory database between 2010 and March 2018. Two additional stones were identified at our institution. Three patients had medical records available for analysis. Results Between 2010 and March 2018, 35 calcium tartrate stones in 25 patients were identified in the Mayo database as well as 2 at our institution (37 stones in 27 patients). Thirty stones were pure calcium tartrate with the remainder having elements of more common stones. The average age was 46.3 (±14.7) with a slightly higher incidence in females (17 vs 10). Of the 3 medical records investigated, all 3 were males (average age 48.7), and each reported consumption of an energy supplement (Spark) routinely. Conclusion The true prevalence of this relatively unknown stone remains unclear and additional investigation is warranted. We believe all stone laboratories should have access to the IR spectra for calcium tartrate tetrahydrate. Attention should be paid to possible causes of this stone, particularly with relation to oral supplements, to aid with future prevention and treatment

Electronic data capture in a rural African setting: evaluating experiences with different systems in Malawi

Background As hardware for electronic data capture (EDC), such as smartphones or tablets, becomes cheaper and more widely available, the potential for using such hardware as data capture tools in routine healthcare and research is increasing. Objective We aim to highlight the advantages and disadvantages of four EDC systems being used simultaneously in rural Malawi: two for Android devices (CommCare and ODK Collect), one for PALM and Windows OS (Pendragon), and a custom-built application for Android (Mobile InterVA – MIVA). Design We report on the personal field and development experience of fieldworkers, project managers, and EDC system developers. Results Fieldworkers preferred using EDC to paper-based systems, although some struggled with the technology at first. Highlighted features include in-built skip patterns for all systems, and specifically the ‘case’ function that CommCare offers. MIVA as a standalone app required considerably more time and expertise than the other systems to create and could not be customised for our specific research needs; however, it facilitates standardised routine data collection. CommCare and ODK Collect both have user-friendly web-interfaces for form development and good technical support. CommCare requires Internet to build an application and download it to a device, whereas all steps can be done offline with ODK Collect, a desirable feature in low connectivity settings. Pendragon required more complex programming of logic, using a Microsoft Access application, and generally had less technical support. Start-up costs varied between systems, and all were considered more expensive than setting up a paper-based system; however running costs were generally low and therefore thought to be cost-effective over the course of our projects. Conclusions EDC offers many opportunities for efficient data collection, but brings some issues requiring consideration when designing a study; the decision of which hardware and software to use should be informed by the aim of data collection, budget, and local circumstances