Spectroscopic characterization and detection of Ethyl Mercaptan in Orion

New laboratory data of ethyl mercaptan, CH$_{3}$CH$_{2}$SH, in the millimeter and submillimeter-wave domains (up to 880 GHz) provided very precise values of the spectroscopic constants that allowed the detection of $gauche$-CH$_3$CH$_2$SH towards Orion KL. 77 unblended or slightly blended lines plus no missing transitions in the range 80-280 GHz support this identification. A detection of methyl mercaptan, CH$_{3}$SH, in the spectral survey of Orion KL is reported as well. Our column density results indicate that methyl mercaptan is $\simeq$ 5 times more abundant than ethyl mercaptan in the hot core of Orion KL.Comment: Accepted for publication in ApJL (30 January 2014)/ submitted (8 January 2014

Dry Friction due to Adsorbed Molecules

Using an adiabatic approximation method, which searches for Tomlinson model-like instabilities for a simple but still realistic model for two crystalline surfaces in the extremely light contact limit, with mobile molecules present at the interface, sliding relative to each other, we are able to account for the virtually universal occurrence of "dry friction." The model makes important predictions for the dependence of friction on the strength of the interaction of each surface with the mobile molecules.Comment: four pages of latex, figure provide

Effects of Defects on Friction for a Xe Film Sliding on Ag(111)

The effects of a step defect and a random array of point defects (such as vacancies or substitutional impurities) on the force of friction acting on a xenon monolayer film as it slides on a silver (111) substrate are studied by molecular dynamic simulations and compared with the results of lowest order perturbation theory in the substrate corrugation potential. For the case of a step, the magnitude and velocity dependence of the friction force are strongly dependent on the direction of sliding respect to the step and the corrugation strength. When the applied force F is perpendicular to the step, the film is pinned forF less than a critical force Fc. Motion of the film along the step, however, is not pinned. Fluctuations in the sliding velocity in time provide evidence of both stick-slip motion and thermally activated creep. Simulations done with a substrate containing a 5 percent concentration of random point defects for various directions of the applied force show that the film is pinned for the force below a critical value. The critical force, however, is still much lower than the effective inertial force exerted on the film by the oscillations of the substrate in experiments done with a quartz crystal microbalance (QCM). Lowest order perturbation theory in the substrate potential is shown to give results consistent with the simulations, and it is used to give a physical picture of what could be expected for real surfaces which contain many defects.Comment: 13 pages, 17 figures, latex plus postscript files for figure

Persistent pain after caesarean section and its association with maternal anxiety and socioeconomic background

Background: Pain, both from the surgical site, and from other sources such as musculoskeletal backache, can persist after caesarean section. In this study of a predominantly socially deprived population we have sought to prospectively examine the association between antenatal maternal anxiety and socioeconomic background and the development of persistent pain of all sources after caesarean section. Methods: Demographic details and an anxiety questionnaire were completed by 205 women before elective caesarean section. On the first postoperative day, pain scores were recorded, and at four months patients were asked to complete a Brief Pain Inventory and an Edinburgh Postnatal Depression Score. Results: Of 205 parturients recruited, 186 records were complete at the hospital admission phase and 98 (52.7%) were complete at the four-month follow-up phase. At recruitment, 15.1% reported pain. At four months 41.8% (95% CI 32.1 to 51.6%) reported pain, of whom pain was a new finding in 35.7% (95% CI 26.2 to 45.2%). Antenatal anxiety was not a significant predictor of severity of new pain at four months (P=0.43 for state anxiety, P=0.52 for trait anxiety). However, four-month pain severity did correlate with social deprivation (P=0.011), postnatal depression (P<0.001) and pain at 24 h (P=0.018). Conclusion: Persistent pain from a variety of sources after caesarean section is common. Our findings do not support the use of antenatal anxiety scoring to predict persistent pain in this setting, but suggest that persistent pain is influenced by acute pain, postnatal depression and socioeconomic deprivation

The Concept of Sustainable Development and Its Impact on the Shaping of Modern International Relations through Global Agreements

The goal of this article is a depiction of the process of the molding of the concept of sustainable development as well as a look at the influence that this concept has exerted on contemporary international politics, especially taking into account agreements of worldwide scope. This article is also an effort at demonstrating that the foundations of the concept of sustainable development can be traced to certain economic theories. The final section of this article is devoted to the characteristics of individual conferences initiated by the United Nations in order to promote enduring and sustainable development on a world scale. Also presented are the achievements of the individual conferences and their roles in demarcating universally obligatory principles and standards of sustainable development.Celem niniejszego artykułu jest scharakteryzowanie genezy kształtowania się Koncepcji Zrównoważonego Rozwoju, a także wskazanie, jaki wpływ miała ona na ukształtowanie się stosunków międzynarodowych w zakresie ochrony środowiska i rozwiązywania problemów społecznych. Przedmiotem analizy są także teorie ekonomiczne, które stały się fundamentem dla wykrystalizowania się koncepcji zrównoważonego rozwoju. Poniższy artykuł jest także próbą wykazania, iż konferencje organizowane przez ONZ na rzecz trwałego i zrównoważonego rozwoju, stały się siła napędową do rozpowszechnienia tej koncepcji w skali światowej

Global Cosmological Parameters Determined Using Classical Double Radio Galaxies

A sample of 20 powerful extended radio galaxies with redshifts between zero and two were used to determine constraints on global cosmological parameters. Data for six radio sources were obtained from the VLA archive, analyzed, and combined with the sample of 14 radio galaxies used previously by Guerra & Daly to determine cosmological parameters. The results are consistent with our previous results, and indicate that the current value of the mean mass density of the universe is significantly less than the critical value. A universe with $\Omega_m$ of unity is ruled out at 99.0% confidence, and the best fitting values of $\Omega_m$ in matter are $0.10^{+0.25}_{-0.10}$ and $-0.25^{+0.35}_{-0.25}$ assuming zero space curvature and zero cosmological constant, respectively. Note that identical results obtain when the low redshift bin, which includes Cygnus A, is excluded; these results are independent of whether the radio source Cygnus A is included. The method does not rely on a zero-redshift normalization. The radio properties of each source are also used to determine the density of the gas in the vicinity of the source, and the beam power of the source. The six new radio sources have physical characteristics similar to those found for the original 14 sources. The density of the gas around these radio sources is typical of gas in present day clusters of galaxies. The beam powers are typically about $10^{45} \hbox{erg s}^{-1}$.Comment: 39 pages includes 21 figures, accepted to Ap

Low-Cost Jetting System; Space and Naval Warfare Systems Command (SPAWAR)

SPAWAR, a research and development side of the U.S. Navy, needed a way to bury classified payloads below the seafloor in order to anchor the devices. They currently use a jetting system that costs around $20,000 to do it, and they desired a cheaper system capable of performing the same tasks. SPAWAR presented the project to Cal Poly Mechanical Engineers as a senior project in the fall of 2016. The design team that decided to take on the project was interested in creating the system with two key factors in mind in order to make the device less expensive. 1. Find the minimal water jet pressure and flow rate requirements to allow for a payload to bury itself. 2. Create the system using as inexpensive stock materials as possible without compromising functional requirements. After creating the system our team was able to test and verify its functionality and found that it was able to successfully bury itself and complete almost every required task. One of the largest issues we ran into was the fact that our Node, or the capsule that holds a payload, was too light and would become buoyant at certain depths. While analyzing the tests we ran, we were able to create a list of recommendations as to what SPAWAR should do when creating their system in order to make it cost effective and functional. The following report details the design, build, test, and report process that the team underwent to create the functioning Low-Cost Jetting System

Quintessence, Cosmology, and Fanaroff-Riley Type IIB Radio Galaxies

Fanaroff-Riley type IIb (FR IIb) radio galaxies provide a modified standard yardstick that allows constraints to be placed on global cosmological parameters. A sample of 20 FR IIb radio galaxies with redshifts between 0 and 2 are compared with the parent population of 70 radio galaxies to determine the coordinate distance to each source. The coordinate-distance determinations are used to constrain the current mean mass-energy density of quintessence $\Omega_q$, the equation of state of the quintessence w, and the current mean mass-energy density of nonrelativistic matter $\Omega_m$; zero space curvature is assumed. Radio galaxies alone indicate that the universe is currently accelerating in its expansion (with 84% confidence); most of the allowed parameter space falls within the accelerating universe region on the $\Omega_m$-w plane. This provides verification of the acceleration of the universe indicated by high-redshift supernovae and suggests that neither method is plagued by systematic errors. It is found that $\Omega_m$ must be less than about 0.5 and the equation of state w of the quintessence must lie between -0.25 and -2.5 at about 90% confidence. Fits of the radio galaxy data constrain the model parameter $\beta$, which describes a relation between the beam power of the active galactic nucleus (AGN) and the total energy expelled through large-scale jets. It is shown that the empirically determined model parameter is consistent with models in which the outflow results from the electromagnetic extraction of rotational energy from the central compact object. A specific relation between the strength of the magnetic field near the AGN and the spin angular momentum per unit mass of the central compact object is predicted

PDS 144: the first confirmed Herbig Ae-Herbig Ae wide binary

PDS 144 is a pair of Herbig Ae stars that are separated by 5.'' 35 on the sky. It has previously been shown to have an A2Ve Herbig Ae star viewed at 83 degrees inclination as its northern member and an A5Ve Herbig Ae star as its southern member. Direct imagery revealed a disk occulting PDS 144 N-the first edge-on disk observed around a Herbig Ae star. The lack of an obvious disk in direct imagery suggested PDS 144 S might be viewed face-on or not physically associated with PDS 144 N. Multi-epoch Hubble Space Telescope imagery of PDS 144 with a 5 year baseline demonstrates PDS 144 N & S are comoving and have a common proper motion with TYC 6782-878-1. TYC 6782-878-1 has previously been identified as a member of Upper Sco sub-association A at d = 145 +/- 2 pc with an age of 5-10 Myr. Ground-based imagery reveals jets and a string of Herbig-Haro knots extending 13' (possibly further) which are aligned to within 7 degrees +/- 6 degrees on the sky. By combining proper motion data and the absence of a dark mid-plane with radial velocity data, we measure the inclination of PDS 144 S to be i = 73 degrees +/- 7 degrees. The radial velocity of the jets from PDS 144 N & S indicates they, and therefore their disks, are misaligned by 25 degrees +/- 9 degrees. This degree of misalignment is similar to that seen in T Tauri wide binaries.Peer reviewe

Ultrafast acoustics for imaging at the nanoscale

In this paper we present a series of experiments which show that 2-D and possibly 3-D imaging with sub-micron resolution is possible by means of ultrafast acoustic techniques. Optical pulses from a Ti:sapphire laser are used to generate picosecond acoustic pulses on one side of a ~1 mm thick Si wafer. The 1 mm distance is sufficient for the acoustic waves to diffract to the far field before they are detected by time-delayed probe pulses from the Ti:sapphire laser. The acoustic waves are either generated by a surface nanostructure or scattered from a buried nanostructure, and an image of that nanostructure is reconstructed through an analysis of the detected acoustic waves.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58182/2/jpconf7_92_012094.pd