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Ring-shaped deposits can be often found after a droplet evaporates on a substrate. If the fluid in the droplet is a pure liquid and its contact line remains pinned during the process, the mechanism behind such ring-shaped deposition is the well-known coffee-stain effect. However, adding small amounts of salt to such a droplet can change the internal flow dramatically and consequently change the deposition mechanism. Due to an increase of surface tension in the contact line region, a Marangoni flow arises which is directed from the apex of the droplet towards the contact line. As a result, particles arrive at the contact line following the liquid-air interface of the droplet. Interestingly, the deposit is also ring-shaped, as in the classical coffee-stain effect, but with a radically different morphology: particles form a monolayer along the liquid-air interface of the droplet, instead of a compact three-dimensional deposit. Using confocal microscopy, we study particle-per-particle how the assembly of the colloidal monolayer occurs during the evaporation of droplets for different initial concentration of sodium chloride and initial particle dilution. Our results are compared with classical diffusion-limited deposition models and open up an interesting scenario of deposits via interfacial particle assembly, which can easily yield homogeneous depositions by manipulating the initial salt and particle concentration in the droplet., Comment: 15 pages, 12 figures

Some members of the vegetal kingdom can achieve surprisingly fast movements making use of a clever combination of evaporation, elasticity and cavitation. In this process, enthalpic energy is transformed into elastic energy and suddenly released in a cavitation event which produces kinetic energy. Here we study this uncommon energy transformation by a model system: a droplet in an elastic medium shrinks slowly by diffusion and eventually transforms into a bubble by a rapid cavitation event. The experiments reveal the cavity dynamics over the extremely disparate timescales of the process, spanning 9 orders of magnitude. We model the initial shrinkage as a classical diffusive process, while the sudden bubble growth and oscillations are described using an inertial-(visco)elastic model, in excellent agreement with the experiments. Such a model system could serve as a new paradigm for motile synthetic materials., Comment: 6 pages, 5 figures

In response to a request from the CERN Scientific Policy Committee (SPC), the machine parameters and expected luminosity performance for several proposed post-LHC collider projects at CERN are compiled: three types of hadron colliders (HL-LHC upgrade, FCC-hh and HE-LHC), a circular lepton collider (FCC-ee), a linear lepton collider (CLIC), and three options for lepton-hadron colliders (LHeC, HE-LHeC, and FCC-eh). Particular emphasis is put on availability, physics run time, and efficiency. The information contained in this document was presented at the SPC Meeting of September 2018. It will serve as one of the inputs to the 2019/20 Update of the European Strategy for Particle Physics.

When two sessile drops of the same liquid touch, they merge into one drop, driven by capillarity. However, the coalescence can be delayed, or even completely stalled for a substantial period of time, when the two drops have different surface tensions, despite being perfectly miscible. A temporary state of non-coalescence arises, during which the drops move on their substrate, only connected by a thin neck between them. Existing literature covers pure liquids and mixtures with low surface activities. In this paper, we focus on the case of large surface activities, using aqueous surfactant solutions with varying concentrations. It is shown that the coalescence behavior can be classified into three regimes that occur for different surface tensions and contact angles of the droplets at initial contact. However, not all phenomenology can be predicted from surface tension contrast or contact angles alone, but strongly depends on the surfactant concentrations as well. This reveals that the merging process is not solely governed by hydrodynamics and geometry, but also depends on the molecular physics of surface adsorption., Comment: 10 pages, 8 figures

Here we employ both dynamic and geometric phase control of light to produce radially modulated vector-vortex modes, the natural modes of optical fibers. We then measure these modes using a vector modal decomposition set-up as well as a tomography measurement, the latter providing a degree of the non-separability of the vector states, akin to an entanglement measure for quantum states. We demonstrate the versatility of the approach by creating the natural modes of a step-index fiber, which are known to exhibit strong mode coupling, and measure the modal cross-talk and non-separability decay during propagation. Our approach will be useful in mode division multiplexing schemes for transport of classical and quantum states., Comment: 6 pages, 4 figures, 1 table

There were four presentations given during the session 'Beam-beam experience in hadron colliders', reporting the beam-beam observations in SPS [1], Tevatron [2], RHIC [3] and HERA [4]. Presentations were followed by discussions. Below we summarize the major observations, findings and results., Comment: 3 pages, contribution to the ICFA Mini-Workshop on Beam-Beam Effects in Hadron Colliders, CERN, Geneva, Switzerland, 18-22 Mar 2013

Mode division multiplexing has been mooted as a future technology to address the impending data crunch of existing fiber networks. Present demonstrations delineate the light source from the mode creation steps, potentially inhibiting integrated solutions. Here we demonstrate an integrated mode generating source in the form of a digitally controlled solid state laser with an intra-cavity spatial light modulator. In our proof-of-principle experiment we create fiber modes on demand and couple them directly into a few-mode fiber, where after transmission they are decoupled by modal decomposition. This is the first demonstration of a single source for encoding information into the spatial modes of light.

These reports present the results of the 2013 Community Summer Study of the APS Division of Particles and Fields ("Snowmass 2013") on the future program of particle physics in the U.S. Chapter 6, on Accelerator Capabilities, discusses the future progress of accelerator technology, including issues for high-energy hadron and lepton colliders, high-intensity beams, electron-ion colliders, and necessary R&D for future accelerator technologies., Comment: 26 pages

The impact of the edges and presence of dopants to the work function (WF) of graphene nanoribbons (GNR) and nanoflakes was studied by an ab initio approach. The strong dependence of the WF upon the GNR structure was found and a promising character for the field emission by the donor type impurities was observed. Basing on the predominant impact of the nanostructure edges to the emission properties, the small graphene flakes were investigated as a possible source for the electron emission. The obtained weak dependence of the low WF values of the graphene flakes on their size and shape allows to suggest that the pure carbon medium with high and uniform emission properties can be fabricated by today technology., Comment: 9 pages, 4 figures

Liquid water and vitreous B$_2$O$_3$ are the endpoints of a continuous range of random networks in which hydrogen bonds gradually replace covalent bonds. Previous work has shown that glasses can be obtained by quenching in the range $x \le$ 0.50. We report the wide-angle x-ray scattering by the liquid phase in the composition range from $x$ = 0.38 to $x$ = 1.00 (pure water) at temperatures just above the liquidus. The first sharp diffraction peak (FSDP) remains at an approximately constant position in the range from $0 \le x \le 0.8$. Beyond this range, the position of the FSDP shifts linearly to higher angles. The relative concentration of the molecular species in the glasses and melts were measured with micro-Raman spectroscopy. Small molecular species are found for glasses and liquids with $x > 0.36$, determining the critical point at which the sample ceases to be a single macromolecule. Molecular water is present in liquids with $x > 0.62$., Comment: 17 pages, 9 figures

Eleven teachers of English in a large, private, English-medium school in India reflected on their beliefs, practices, and activities related to teaching English in India. In the survey, respondents freely acknowledged the premier position of English in academics and the world at large and unequivocally stated that their students should learn to communicate orally both among themselves and with other native speakers. However, oral and listening skills were not given much importance in the classroom. Teachers cited various barriers to implementing them: large class sizes inhibiting small group activities and increasing the noise level (leading to questions about discipline and classroom management); test-driven curricula; the low level of education of parents and their lack of mastery of English; and the predominance of the first language. Assessment and patterns of reporting student achievement did not accommodate learning oral skills. (Author/SM)

One solution to the problem of providing instruction for medical students is to use nurses as clinical instructors for each of the required clinical clerkships. A study was conducted to evaluate the use of nurses as instructors in a school of medicine by studying students' perceptions of nurse instructors. Focus groups and individual interviews were conducted with 43 fourth-year medical students. Findings show that students think that nurse instructors fill gaps in knowledge by teaching basic concepts and provide a more comfortable learning environment than physician medical faculty. Nurses are perceived to bring clinical hands-on experience to the role, to offer support to students, and to bring organization to the clerkships. Overall, students view the role of nurse instructors as positive. Appendixes contain the interview protocol and the consent to participate in research. The research proposal introduces the study. (SLD)

It is shown that lines of adsorbed hydrogen pair atoms divide the graphene sheet into strips and form hydrogen-based superlattice structures (2HG-SL). We show that the forming of 2HG-SL drastically changes the electronic properties of graphene from semimetal to semiconductor. The electronic spectra of "zigzag" (n,0) 2HG-SL is similar to that of (n,0) carbon nanotubes and have a similar oscillation of band gap with number n, but with non-zero minimal values. The composite dual-periodic (n,0)+(m,0) 2HG-SLs of "zigzag" strips are analyzed, with the conclusion that they may be treated as quasi-two-dimensional heterostructures. We also suggest an experimental way of fabricating hydrogen superlattices., Comment: 12 pages, 3 figures

We have determined the physical ground state properties of the compounds CeRuPO and CeOsPO by means of magnetic susceptibility chi(T), specific heat C(T), electrical resistivity rho(T), and thermopower S(T) measurements. chi(T) reveals a trivalent 4f1 cerium state in both compounds. For CeRuPO a pronounced decrease of rho(T) below 50K indicates the onset of coherent Kondo scattering which is confirmed by enhanced S(T). The temperature and magnetic field dependence of chi(T) and C(T) evidence ferromagnetic (FM) order at TC=15K. Thus, CeRuPO seems to be one of the rare example of a FM Kondo lattice. In contrast, CeOsPO shows antiferromagnetic order at TN=4.4K despite only minor changes in lattice parameters and electronic configuration. Additional 31P NMR results support these scenarios. LSDA+U calculations evidence a quasi two dimensional electronic band structure, reflecting a strong covalent bonding within the CeO and RuP layers and a weak ionic like bonding between the layers., Comment: accepted in Phys. Rev. B, high quality figures: http://www.cpfs.mpg.de/~krellner/

The structures and electron properties of new superlattices formed on graphene by adsorbed hydrogen molecules are theoretically described. It has been shown that superlattices of the (n, 0) zigzag type with linearly arranged pairs of H atoms have band structures similar to the spectra of (n, 0) carbon nanotubes. At the same time, superlattices of the (n, n) type with a "staircase" of adsorbed pairs of H atoms are substantially metallic with a high density of electronic states at the Fermi level and this property distinguishes their spectra from the spectra of the corresponding (n, n) nanotubes. The features of the spectra have the Van Hove form, which is characteristic of each individual superlattice. The possibility of using such planar structures with nanometer thickness is discussed., Comment: 5 pages, 4 figures

It has been found that periodically closely spaced vacancies on a graphite sheet cause a significant rearrange-ment of its electronic spectrum: metallic waveguides with a high density of states near the Fermi level are formed along the vacancy lines. In the direction perpendicular to these lines, the spectrum exhibits a semimetal or semiconductor character with a gap where a vacancy miniband is degenerated into impurity levels., Comment: 4 pages, 3 figures

Responding to the dramatic changes in the style and form of communication, a communication instructor integrated the Internet into his communication courses at a liberal arts college. Students are required to sign up for a discussion group (listserv) that focuses on the course offering as well as a discussion group in their area of interest. Every other week, students write summaries of what happened in their discussion groups and e-mail it to the instructor. Students are encouraged to access as much information as they can as part of the information gathering process for their writing assignments. Students are also expected to conduct themselves according to the "rules" of the Internet. Five reasons students engage in this assignment are: (1) to gain an understanding of how to use electronic media; (2) to obtain a greater appreciation for the discipline of communication; (3) to start "networking" in their area of concentration; (4) to develop an understanding of the amount of information available; and (5) to combat the perception that graduates of small liberal arts colleges received little or no exposure to the latest technologies while in college. The assignment also led to an increase in the amount and quality of communication experienced in the student/professor relationship. The purposes for which students used electronic mail focused upon general communication, apologies, clarification of assignments, and to further examine in-class discussions. Electronic mail has afforded an additional channel of communication between the instructor and his students. (Contains nine references.) (RS)