Methane hydrate: shifting the coexistence temperature to higher temperatures with an external electric field

In the present work, we used molecular dynamic simulations of the equilibrium NPT ensemble to examine the effect of an external electric field on the three-phase coexistence temperature of methane gas, liquid water and methane hydrate. For these simulations, we used the TIP4P/Ice rigid water model and a single-site model for methane. The simulations were implemented at two pressures, 400 and 250bar, over temperatures ranging from 285 to 320K and from 280 to 315K, respectively. The application of an external electric field in the range of 0.1-0.9caused the effect of the thermal vibrations of the water molecules to become attenuated. This resulted in a shift of the three-phase coexistence temperature to higher temperatures. Electric fields below this range did not cause a difference in the coexistence temperature, and electric fields above this range enhanced the thermal effect. The shift had a magnitude of 22.5K on average.Peer ReviewedPostprint (author's final draft

Accessory soleus muscle in an athlete. Presentation of a case and a literature review

The incidence of an accessory soleus muscle, according to autopsy studies, ranged from 0.5 to 6.0% of the population. The typical presentation is a soft mass in the posteromedial distal third of the leg, which increases in size with physical activity, especially plantar flexion. It is accompanied by pain with exercise in 67% of reported cases. The treatment of choice is conservative, but when it causes compartment syndrome, fasciotomy should be performed. If a patient has symptoms of claudication or nerve compression, a complete excision of the muscle is required. We report the case of an athlete who had a symptomatic accessory soleus muscle, which was studied by standard X-ray, ultrasound and magnetic resonance imaging (MRI)

Músculo sóleo accesorio de una deportista. A propósito de un caso y revisión de la bibliografía

Según los estudios necrópsicos, la incidencia del músculo sóleo accesorio fluctúa entre el 0,5 y el 6,0% de la población. La presentación típica es una tumoración blanda del tercio distal posteromedial de la pierna que aumenta de tamaño con la actividad física, especialmente con la flexión plantar. Se acompaña de dolor con el ejercicio en el 67% de los casos publicados. El tratamiento de elección es conservador, pero cuando provoca un síndrome compartimental se debe realizar la fasciotomía y, en el caso de tener síntomas de claudicación o compresión nerviosa, se necesitará una escisión completa del músculo. Presentamos el caso clínico de una deportista que presenta un músculo sóleo accesorio sintomático que fue estudiado mediante radiología, ecografía y resonancia magnética nuclear (RMN)

Múscul soli accessori d’una esportista. A propòsit d’un cas i revisió bibliogràfica

Segons els estudis necròpsics, la incidència del múscul soli accessori fluctua entre el 0,5 i el 6,0% de la població. La presentació típica és una tumoració tova al terç distal posteromedial de la cama, que augmenta de grandària amb l’activitat física, especialment amb la flexió plantar. S’acompanya de dolor amb l’exercici en el 67% dels casos reportats. El tractament d’elecció és conservador, però quan causa la síndrome compartimental, s’ha de fer una fasciotomia. Si un pacient té símptomes de claudicació o compressió del nervi, cal l’extirpació completa del múscul. Presentem el cas clínic d’una esportista que presenta un múscul soli accessori simptomàtic, que fou estudiat mitjançant radiologia, ecografia i ressonància magnètica nuclear (RMN)

A Multiple System of Radio Sources at the Core of the L723 Multipolar Outflow

We present high angular resolution Very Large Array multi-epoch continuum observations at 3.6 cm and 7 mm towards the core of the L723 multipolar outflow revealing a multiple system of four radio sources suspected to be YSOs in a region of only ~4 arcsecs (1200 AU) in extent. The 3.6 cm observations show that the previously detected source VLA 2 contains a close (separation ~0.29 arcsecs or ~90 AU) radio binary, with components (A and B) along a position angle of ~150 degrees. The northern component (VLA 2A) of this binary system is also detected in the 7 mm observations, with a positive spectral index between 3.6 cm and 7 mm. In addition, the source VLA 2A is associated with extended emission along a position angle of ~115 degrees, that we interpret as outflowing shock-ionized gas that is exciting a system of HH objects with the same position angle. A third, weak 3.6 cm source, VLA 2C, that is detected also at 7 mm, is located ~0.7 arcsecs northeast of VLA 2A, and is possibly associated with the water maser emission in the region. The 7 mm observations reveal the presence of an additional source, VLA 2D, located ~3.5 arcsecs southeast of VLA 2A, and with a 1.35 mm counterpart. All these radio continuum sources have a positive spectral index, compatible with them being YSOs. We also propose that the high velocity CO emission observed in the region could be the superposition of multiple outflows (at least three independent bipolar outflows) excited by the YSOs located at the core, instead of the previous interpretations in terms of only one or two outflows.Comment: Accepted for publication in The Astrophysical Journal (2007 December 6

Effect of Caffeine on Heart Rate and Calories Burned During Exercise

Four active collegiate level students were asked to participate in a 3 day study, conducted in a strict environment. These students were required to perform the same exact exercise each day at the same time upon waking on an empty stomach following a fasted sleep. All individuals performed the exercise at 7:00 AM. On day one, the participant was to perform the exercise with no caffeine consumption. The following day, the participant was to drink one cup of coffee and perform the required exercise. On the last day of the experiment, each participant drank two cups of coffee before the exercise was performed. The exercise was one mile of walking on a flat treadmill at a speed of 3.5mph. These individuals were wearing a Garmin fitness watch and the heart rate strap that was included in the packaging. Immediately following exercise, these individuals took note of both their heart rate and calories burned. The basis of this study is to show the effects of caffeine on calorie burn and heart rate fluctuation. Following this study, it is important to note that all four participants showed a slight increase in both calories burned and heart rate following the required exercise on each day. The average calories burned with no caffeine was 109.25 and a heart rate of 103 beats per minute. When one cup of coffee was consumed by each individual, the average readings were 118.5 calories burned and a heart rate of 110.25 beats per minute. On the third and final day, the averages were 123.75 calories burned and a heart rate of 120 beats per minute. Thus, proving that caffeine consumption before exercise can help increase heart rate and in return burn more calories. This information can be especially helpful to all individuals trying to lose weight

Fractionation of potentially toxic elements in urban soils from five European cities by means of a harmonised sequential extraction procedure

The revised (four-step) BCR sequential extraction procedure has been applied to fractionate the chromium, copper, iron, manganese, nickel, lead and zinc contents in urban soil samples from public-access areas in five European cities. A preliminary inter-laboratory comparison was conducted and showed that data obtained by different laboratories participating in the study were sufficiently harmonious for comparisons to be made between cities and land types (e.g. parks, roadside, riverbanks, etc.). Analyte recoveries by sequential extraction, with respect to direct aqua regia digestion, were generally acceptable (100 ± 15%). Iron, nickel and, at most sites, chromium were found mainly in association with the residual phase of the soil matrix. Copper was present in the reducible, oxidisable and residual fractions, whilst zinc was found in all four sequential extracts. Manganese was strongly associated with reducible material as, in some cities, was lead. This is of concern because high lead concentrations were present in some soils (>500 mg kg−1) and the potential exists for remobilisation under reducing conditions. As would be expected, extractable metal contents were generally highest in older, more heavily industrialised cities. Copper, lead and zinc showed marked (and often correlated) variations in concentrations between sites within the same city whereas manganese and, especially, iron, did not. No overall relationships were, however, found between analyte concentrations and land use, nor between analyte partitioning and land use

The Collimated Jet Source in IRAS 16547-4247: Time Variation, Possible Precession, and Upper Limits to the Proper Motions along the Jet Axis

The triple radio source detected in association with the luminous infrared source IRAS 16547-4247 has previously been studied with high angular resolution and high sensitivity with the Very Large Array at 3.6 cm wavelength. In this paper, we present new 3.6 cm observations taken 2.68 years after the first epoch that allow a search for variability and proper motions, as well as the detection of additional faint sources in the region. We do not detect proper motions along the axis of the outflow in the outer lobes of this source at a 4σ upper limit of ~160 $km s^{−1}$. This suggests that these lobes are probably working surfaces where the jet is interacting with a denser medium. However, the brightest components of the lobes show evidence of precession, at a rate of $0\mathring{.}08 yr^{−1}$ clockwise in the plane of the sky. It may be possible to understand the distribution of almost all the identified sources as the result of ejecta from a precessing jet. The core of the thermal jet shows significant variations in flux density and morphology. We compare this source with other jets in low- and high-mass young stars and suggest that the latter can be understood as a scaled-up version of the former.Astronom