bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal conductivity of bulk and thin-film silicon: A Landauer approach
Authors: Jeong Changwook , Datta Supriyo , Lundstrom Mark
Published: May 2012

The question of what fraction of the total heat flow is transported by phonons with different mean-free-paths is addressed using a Landauer approach with a full dispersion description of phonons to evaluate the thermal conductivities of bulk and thin film silicon. For bulk Si, the results reproduce those of a recent molecular dynamic treatment showing that about 50% of the heat conduction is carried by phonons with a mean-free-path greater than about 1 μm. For the in-plane thermal conductivity of thin Si films, we find that about 50% of the heat is carried by phonons with mean-free-paths shorter than in the bulk. When the film thickness is smaller than ∼0.2 μm, 50% of the heat is carried by phonons with mean-free-paths longer than the film thickness. The cross-plane thermal conductivity of thin-films, where quasi-ballistic phonon transport becomes important, is also examined. For ballistic transport, the results reduce to the well-known Casimir limit [H. B. G. Casimir, Physica 5, 495–500 (1938)]. These results shed light on phonon transport in bulk and thin-film silicon and demonstrate that the Landauer approach provides a relatively simple but accurate technique to treat phonon transport from the ballistic to diffusive regimes.
Porosity-induced relaxation of strains in GaN layers studied by means of micro-indentation and optical spectroscopy
Authors: Najar Adel , Gerland Michel , Jouiad Mustapha
Published: May 2012

We report the fabrication of porous GaN nanostructures using UV-assisted electroless etching of bulk GaN layer grown on c-plane sapphire substrate in a solution consisting of HF:CH3OH:H2O2. The morphology of the porous GaN nanostructures was characterized for different etching intervals using high resolution scanning electron microscopy. The geometry and size of resultant pores do not appear to be affected by the etching time; however, the pore density was augmented for longer etching time. Micro-indentation tests were carried out to quantify the indentation modulus for different porous GaN nanostructures. Our results reveal a relationship between the elastic properties and the porosity kinetics, i.e., a decrease of the elastic modulus was observed with increasing porosity. The photoluminescence (PL) and Raman measurements carried out at room temperature for the etched samples having a high degree of porosity revealed a strong enhancement in intensity. Also, the peak of the PL wavelength was shifted towards a lower energy. The high intensity of PL was correlated to an increase of scattered photons within the porous media and to the reduction of the dislocation density.
Enhancing photocurrent transient spectroscopy by electromagnetic modeling
Authors: Diesinger H. , Panahandeh-Fard M. , Wang Z. , Baillargeat D. , Soci C.
Published: May 2012

The shape and duration of photocurrent transients generated by a photoconductive switch depend on both the intrinsic response of the active material and the geometry of the transmission line structure. The present electromagnetic model decouples both shape forming contributions. In contrast to previously published work, it accounts for the particular operating mode of transient spectroscopy. The objective is to increase the time resolution by two approaches, by optimizing structural response and by deconvolving it from experimental data. The switch structure is represented by an effective transimpedance onto which the active material acts as current generator. As proof of concept, the response of a standard microstrip switch is modeled and deconvolved from experimental data acquired in GaAs, yielding a single exponential material response and hence supporting the validity of the approach. Beyond compensating for the response deterioration by the structure, switch architectures can be a priori optimized with respect to frequency response. As an example, it is shown that a microstrip gap that can be deposited on materials incompatible with standard lithography reduces pulse broadening by an order of magnitude if it is provided with transitions to coplanar access lines.
Synchronizability of small-world networks generated from ring networks with equal-distance edge additions
Authors: Tang Longkun , Lu Jun-an , Chen Guanrong
Published: May 2012

This paper investigates the impact of edge-adding number m and edge-adding distance d on both synchronizability and average path length of NW small-world networks generated from ring networks via random edge-adding. It is found that the synchronizability of the network as a function of the distance d is fluctuant and there exist some d that have almost no impact on the synchronizability and may only scarcely shorten the average path length of the network. Numerical simulations on a network of Lorenz oscillators confirm the above results. This phenomenon shows that the contributions of randomly added edges to both the synchronizability and the average path length are not uniform nor monotone in building an NW small-world network with equal-distance edge additions, implying that only if appropriately adding edges when building up the NW small-word network can help enhance the synchronizability and/or reduce the average path length of the resultant network. Finally, it is shown that this NW small-world network has worse synchronizability and longer average path length, when compared with the conventional NW small-world network, with random-distance edge additions. This may be due to the fact that with equal-distance edge additions, there is only one shortcut distance for better information exchange among nodes and for shortening the average path length, while with random-distance edge additions, there exist many different distances for doing so.
Te-based chalcogenide films with high thermal stability for phase change memory
Authors: Wang Guoxiang , Shen Xiang , Nie Qiuhua , Chen Fen , Wang Xunsi , Fu Jing , Chen Yu , Xu Tiefeng , Dai Shixun , Zhang Wei , Wang Rongping
Published: May 2012

This study reports on the synthesis of tellurium-based chalcogenide films that have high thermal stability for phase change memory application. Several Te-based chalcogenide alloys of In-Bi-Te, Ag-Bi-Te, In-Sb-Te, Sn-Sb-Te, Zn-Ge-Te, and Ga-Ge-Te are reported. Their thermal, optical, and electrical properties are investigated. The results show that Bi-Te-based films have a higher crystallization temperature and greater activation energy compared with the other Sb-Te-based and Ge-Te-based films. Especially, In2.8Bi36.6Te60.6 film exhibits high crystallization temperature (252 °C) and great activation energy (5.16 eV), showing much improved amorphous thermal stability. A relatively wider optical band gap (0.674 eV) of thermal annealed In2.8Bi36.6Te60.6 film is obtained. In addition, it also has a higher amorphous/crystalline resistance ratio of about 105, implying that current consumption could be low in the phase-change memory operation.
Screened field enhancement factor for a tall closely spaced array of identical conducting posts and implications for Fowler-Nordheim-type equations
Authors: Forbes Richard G.
Published: May 2012

For a floating-sphere model of an array of identical cylindrical posts, Zhbanov et al. [J. Appl. Phys. 110, 114311 (2011)] derive a limiting formula (as post height increases) for the screened field enhancement factor. An alternative derivation is given here for a simpler variant of this formula: more approximation is involved, but our derivation is more direct and explains the physical mechanism of collective screening in this limit more clearly. For a tall closely spaced array, the simplified formula also leads to simple expressions for the area efficiency of emission αM and for the macroscopic pre-exponential correction factor λM that needs to be included in “full” macroscopic Fowler-Nordheim-type equations that describe the average current density JM emitted from a large area field emitter.
An in situ set up for the detection of CO2 from catalytic CO oxidation by using planar laser-induced fluorescence
Authors: Zetterberg J. , Blomberg S. , Gustafson J. , Sun Z. W. , Li Z. S. , Lundgren E. , Aldén M.
Published: May 2012

We report the first experiment carried out on an in situ setup, which allows for detection of CO2 from catalytic CO oxidation close to a model catalyst under realistic reaction conditions by the means of planar laser-induced fluorescence (PLIF) in the mid-infrared spectral range. The onset of the catalytic reaction as a function of temperature was followed by PLIF in a steady state flow reactor. After taking into account the self-absorption of CO2, a good agreement between the detected CO2 fluorescence signal and the CO2 mass spectrometry signal was shown. The observed difference to previously measured onset temperatures for the catalytic ignition is discussed and the potential impact of IR-PLIF as a detection technique in catalysis is outlined.
Nonvolatile floating gate organic memory device based on pentacene/CdSe quantum dot heterojuction
Authors: Shin Ik-Soo , Kim Jung-Min , Jeun Jun-Ho , Yoo Seok-Hyun , Ge Ziyi , Hong Jong-In , Ho Bang Jin , Kim Yong-Sang
Published: May 2012

An organic floating-gate memory device using CdSe quantum dots (QDs) as a charge-trapping element was fabricated. CdSe QDs were localized beneath a pentacene without any tunneling insulator, and the QD layer played a role as hole-trapping sites. The band bending formed at the junction between pentacene and QD layers inhibited back-injection of holes trapped in CdSe into pentacene, which appeared as a hysteretic capacitance-voltage response during the operation of the device. Nearly, 60% of trapped charge was sustained even after 104 s in programmed state, and this long retention time can be potentially useful in practical applications of non-volatile memory.
Growth of sputter-deposited metamagnetic epitaxial Ni-Co-Mn-In films
Authors: Niemann R. , Schultz L. , Fähler S.
Published: May 2012

Metamagnetic thin films represent a promising geometry for more efficient magnetocaloric cooling applications due to a fast heat transfer. Here, we identify suitable growth conditions to obtain epitaxial Ni-Mn-In-Co films with a metamagnetic transition in vicinity of room temperature. We show that both increased substrate temperature and target aging result in loss of indium. This can be attributed to evaporation and preferential sputtering, respectively. We present a model that treats the effect of target aging and temperature dependence of evaporation on the film composition independently and enables predictions of the film composition as a function of initial target composition, target age, and deposition temperature. Furthermore, our analysis reveals that a sufficient degree of chemical B2 order is required for a transformation, in addition to an appropriate film composition.
Hybrid carbon nanostructure assemblage for high performance pseudo-capacitors
Authors: Mishra A. K. , Ramaprabhu S.
Published: May 2012

Investigation of novel nanocomposites for pseudo-capacitors with high capacitance and energy density is the spotlight of current energy research. In the present work, hybrid carbon nanostructure assemblage of graphene and multiwalled carbon nanotubes has been used as carbon support to nanostructured RuO2 and polyaniline for high energy supercapacitors. Maximum specific capacitances of 110, 235 and 440 F g−1 at the voltage sweep rate of 10 mV s−1 and maximum energy densities of 7, 12.5 and 20.5 Wh kg−1 were observed for carbon assemblage and its RuO2 and polyanilne decorated nanocomposites, respectively, with 1M H2SO4 as electrolyte.
Adsorption of perfluorooctanoic acid and perfluorooctanesulfonic acid to iron oxide surfaces as studied by flow-through ATR-FTIR spectroscopy
Authors: Gao Xiaodong , Chorover Jon
Published: May 2012

Environmental contextPerfluoroalkyl compounds are organic contaminants that exhibit strong resistance to chemical- and microbial-degradation. As partitioning between solid and aqueous phases is expected to control the transport of perfluoroalkyl compounds, we studied the molecular mechanisms of their adsorption–desorption at a representative Fe oxide surface using in situ molecular spectroscopy. The results provide valuable information on the types of bonds formed, and enable a better understanding of the transport and fate of these organic contaminants in natural environments.
AbstractThe kinetics and mechanisms of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) adsorption to nanoparticulate hematite (α-Fe2O3) from aqueous solutions were examined using in situ, flow-through attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. Results indicate that both PFOA and PFOS molecules are retained at the hydrophilic hematite surface and the adsorption shows strong pH dependence. However, ATR-FTIR data reveal that PFOA and PFOS are bound to the iron oxide by different mechanisms. Specifically, in addition to electrostatic interactions, PFOA forms inner-sphere Fe–carboxylate complexes by ligand exchange, whereas the PFOS sulfonate group forms outer-sphere complexes and possibly hydrogen-bonds at the mineral surface. Both solution pH and surface loading affect adsorption kinetics. Faster adsorption was observed at low pH and high initial PFC concentrations. Sorption kinetics for both compounds can be described by a pseudo-second-order rate law at low pH (pH 3.0 and 4.5) and a pseudo-first-order rate law at high pH (pH 6.0). Sorption isotherm data for PFOA derived from spectroscopic results exhibit features characteristic of ionic surfactant adsorption to hydrophilic charged solid surfaces.
Nutrient exchange of extensive cyanobacterial mats in an arid subtropical wetland
Authors: Adame Maria Fernanda , Reef Ruth , Grinham Alistair , Holmes Glen , Lovelock Catherine E.
Published: May 2012

Cyanobacterial mats cover extensive areas of subtropical arid coastal wetlands and are sites of active nutrient exchange. To assess spatial (low v. high in the intertidal zone) and temporal (day v. night) variability in nitrogen (N) exchange in arid Exmouth Gulf, Western Australia, we measured nutrient exchange (NOx–-N, NH4+ and soluble reactive phosphorus) during tidal inundation and N fixation of cyanobacterial mats before and during an unusual period of heavy rainfall. Additionally, we investigated the species composition within the cyanobacterial mat. We hypothesised that nutrients are released to the floodwater during tidal inundation, that N fixation is a significant path of N incorporation, that highest N fixation rates occur in the low intertidal zone at night, and that the cyanobacterial mat community composition varies across the intertidal zone. Our results showed that nutrients were removed from the floodwater during tidal inundation. N fixation accounted for 34% of N incorporation, with highest rates in the lower intertidal zone during the day. The cyanobacterial mat was dominated by Microcoleus chthonoplastes, but composition varied across the intertidal zone. The present study provided evidence of temporal and spatial variability in nutrient exchange and implied an important role of cyanobacterial mats in coastal production.
Invertebrate colonisation during leaf processing of native, exotic and artificial detritus in a tropical stream
Authors: Gonçalves José Francisco , Rezende Renan de Souza , França Juliana , Callisto Marcos
Published: May 2012

The relationship between leaf breakdown and colonisation by invertebrates in tropical aquatic ecosystems is poorly understood, especially in regard to the added problem of the potential effects of exotic species. To assess the colonisation by invertebrates during leaf breakdown in a third-order headwater stream in south-eastern Brazil, we conducted an experiment using the native species Miconia chartacea, the exotic species Eucalyptus grandis and artificial leaves. We hypothesised that the quality of the detritus and the leaf shape influence invertebrate colonisation because of the quality of the food and refuge offered by leaf detritus. Invertebrate density and richness were higher on leaves of E. grandis than on those of M. chartacea. Taxon richness did not differ among M. chartacea and the two sizes of artificial leaves offered, probably as a function of the chemical composition of E. grandis. Total invertebrate density was significantly higher in the organic detritus, suggesting that detritus provides food for the organisms. Our results indicate that the colonisation of invertebrates is probably affected by the chemical composition of detritus. Contrary to expectations, the community of invertebrates had no difficulty in colonising E. grandis, although it is an exotic species. In addition, the shredder activity did not influence leaf breakdown. These results may indicate that the invertebrates in this stream tend to behave as generalist feeders.
First record of photosynthetic cyanobacterial symbionts from mesophotic temperate sponges
Authors: Keesing John K. , Usher Kayley M. , Fromont Jane
Published: May 2012

Cyanobacterial symbionts may enable sponges to play a critical role in bentho-pelagic coupling, recycling nutrients at the benthic surface and providing a key requirement for ecosystem function. This is the first study to investigate the depths to which these symbioses are viable and the first record of photosynthetic sponges (i.e. sponges having a symbiotic relationship with photosynthetic cyanobacteria) from mesophotic temperate habitats. Sponges with high levels of photosynthetic cyanobacteria occurred at depths of up to 50 m, medium levels to 75 m and low levels to 150 m off south-western Australia. The proportion of sponges that showed no epifluorescence increased greatly with depth. Cyanobacterial symbionts sequenced from sponges at 40 and 50 m belonged to the genera Synechococcus and Synechocystis. Our results verify that the domain of photosynthetic sponges is not just tropical or shallow water temperate environments. Sponges made up the highest biomass of biota across all the sites we sampled from depths of 30–150 m and we hypothesise that photosynthetic cyanobacterial symbionts may be important in facilitating sponges to dominate habitats at these depths off Australia’s oligotrophic west coast.
Statistical phylogeographic tests of competing 'Lake Carpentaria hypotheses' in the mouth-brooding freshwater fish, Glossamia aprion (Apogonidae)
Authors: Cook Benjamin D. , Adams Mark , Mather Peter B. , Hughes Jane M.
Published: May 2012

Glacial cycles during the Pleistocene reduced sea levels and created new land connections in northern Australia, where many currently isolated rivers also became connected via an extensive paleo-lake system, ‘Lake Carpentaria’. However, the most recent period during which populations of freshwater species were connected by gene flow across Lake Carpentaria is debated: various ‘Lake Carpentaria hypotheses’ have been proposed. Here, we used a statistical phylogeographic approach to assess the timing of past population connectivity across the Carpentaria region in the obligate freshwater fish, Glossamia aprion. Results for this species indicate that the most recent period of genetic exchange across the Carpentaria region coincided with the mid- to late Pleistocene, a result shown previously for other freshwater and diadromous species. Based on these findings and published studies for various freshwater, diadromous and marine species, we propose a set of ‘Lake Carpentaria’ hypotheses to explain past population connectivity in aquatic species: (1) strictly freshwater species had widespread gene flow in the mid- to late Pleistocene before the last glacial maximum; (2) marine species were subdivided into eastern and western populations by land during Pleistocene glacial phases; and (3) past connectivity in diadromous species reflects the relative strength of their marine affinity.
Terrestrial subsidies in the diets of stream fishes of the USA: comparisons among taxa and morphology
Authors: Sullivan Mario L. , Zhang Yixin , Bonner Timothy H.
Published: May 2012

Terrestrial food subsidies are important energy sources to stream fishes worldwide. However, their importance is not fully understood, except perhaps for some salmonid communities. Using the published literature, we investigated patterns of fish taxonomy and jaw morphology in the consumption of terrestrial food subsidies by non-salmonid stream fishes in the USA. We hypothesised that: (1) in general, non-salmonid fishes would consume terrestrial food items to the same extent as salmonids; and (2) subsidy consumption would be associated with jaw morphology. Cyprinids and fundulids consumed terrestrial subsidies approaching levels observed in salmonids (20–44%) whereas other groups (e.g. catostomids and moronids) consumed far less (<2%) terrestrial food. Fishes with terminal jaw positions tended to consume more terrestrial items than those with subterminal or inferior jaw positions. Within a species, there were highly variable propensities for consuming terrestrial subsidies. Our findings justify focusing on trophic linkages between fishes and riparian systems across a wide range of taxa, especially considering the spatio-temporal variability of environmental conditions across a variety of habitats. It is necessary to assess the relative contribution of terrestrial subsidies in fish growth and population dynamics with a focus on nutritional and energetic benefits across different groups.
Demography, fishery yield and potential management strategies of painted spiny lobster (Panulirus versicolor) at Northwest Island, Great Barrier Reef, Australia
Authors: Frisch Ashley J. , Hobbs Jean-Paul A.
Published: May 2012

Quantification of demographic parameters is important for understanding how populations interact with their environment and for developing sustainable harvest strategies. Our aims were to quantify demographic parameters and yield of painted spiny lobster (Panulirus versicolor) at Northwest Island, Great Barrier Reef and review fishery management regulations in view of the findings. Using catch-curve analysis and an intensive mark–recapture program, the local lobster population was found to be sparsely distributed (~1.3 ha–1), with low rates of natural mortality (0.25–0.28 year–1) and immigration (0.05 ha–1 year–1). Under current management regulations (no minimum size limit; MSL), yield-per-recruit peaked at 0.38 kg when fishing mortality was 0.4 year–1. Implementation of a 100-mm (carapace length) MSL is recommended because it provides the best compromise between yield and stock size and has minimal impact on existing fishing practices. Revocation of the prohibition on possessing egg-bearing females is also recommended because it would reduce wastage of lobsters that are inadvertently killed by spear-fishers and because there appears to be little chance of localised recruitment overfishing. This study provides the first estimate of mortality rate for P. versicolor and highlights the importance of this parameter for understanding demographic processes and optimising management regulations.
Remediation of a perched stream culvert with ropes improves fish passage
Authors: David B. O. , Hamer M. P.
Published: May 2012

Worldwide, human-mediated disruption of river networks by artificial structures negatively affects migratory fish species. To creatively solve part of this problem, we assessed the effectiveness of mussel spat ropes for improving fish passage past perched culvert structures. We used a before–after–control–treatment design to test our hypothesis that relative abundances of ‘young-of-the-year’ migratory fish species would increase following rope installation in a New Zealand stream. Results following remediation indicated a significant three- to four-fold increase in fish abundance relative to a control stream. Although four species (banded kokopu (Galaxias fasciatus), redfin bullies (Gobiomorphus huttoni), longfin eels (Anguilla dieffenbachii) and shortfin eels (Anguilla australis)) were present at both the treatment and control stream sites, the increased fish relative abundance at the treatment site was driven primarily by an increase in ‘young-of-the-year’ banded kokopu. The present study has shown that mussel spat ropes can significantly improve fish relative abundances above severely perched culverts, but may not be effective for all species present. Future use of ropes for evaluating passage efficacy for other species, and for a wider range of barrier situations globally, may greatly extend the application of this cost-effective tool.
Synchronous Cycling of Ichthyophoniasis with Chinook Salmon Density Revealed during the Annual Yukon River Spawning Migration
Authors: Zuray Stanley , Kocan Richard , Hershberger Paul
Published: May 2012

Populations of Chinook salmon Oncorhynchus tshawytscha in the Yukon River declined by more than 57% between 2003 and 2010, probably the result of a combination of anthropogenic and environmental factors. One possible contributor to this decline is Ichthyophonus, a mesomycetozoan parasite that has previously been implicated in significant losses of fish, including Chinook salmon. A multiyear epidemiological study of ichthyophoniasis in the Yukon River revealed that disease prevalence and Chinook salmon population abundance increased and decreased simultaneously (i.e., were concordant) from 1999 to 2010. The two values rose and fell synchronously 91% of the time for female Chinook salmon and 82% of the time for males; however, there was no significant correlation between Ichthyophonus prevalence and population abundance. This synchronicity might be explained by a single factor, such as a prey item that is critical to Chinook salmon survival as well as a source of Ichthyophonus infection. The host–parasite relationship between Ichthyophonus and migrating Chinook salmon from 2004 to 2010 was similar to that reported for the previous 5 years. During 2004–2010, overall disease prevalence was significantly higher among females (21%) than among males (8%), increased linearly with fish length for both males and females, and increased in both sexes as the fish progressed upriver. These regularly occurring features of host–parasite dynamics confirm a stable base of transmission for Ichthyophonus. However, from 2003 to 2010, disease prevalence decreased from 30% to just 8% in males and from 45% to 9% in females, paralleling a similar decline in Chinook salmon abundance during the same period. These findings may help clarify questions regarding the complex host–parasite dynamics that occur in marine species such as herrings Clupea spp., which have less well‐defined population structures.
Rossetti's Obsessionby Ramon Saizarbitoria: On the seduction of minority literary fields
Authors: Apalategui Ur
Published: May 2012

InRossettiren obsesioa(Rossetti's Obsession), a short and explicitly meta-literary novel published in 2000, Ramon Saizarbitoria presents a Basque writer wrestling a formidable lover: the Spanish readership. The question that Eugenia, the woman from Madrid, constantly asks the writer, “¿Qué os pasa a los vascos?” (“What's wrong with you Basques?”), encapsulates the ambiguity of the relationship which unites these two indisputably allegorical characters. The difficult interaction between the powerful Spanish literary field and the emerging Basque literary field, doomed to coexist and moved by reciprocal feelings of fascination and irritation, becomes the novel's subject matter. Is translation — and its corollary, an access to a larger literary market — a pure and neutral instrument of liberation for the writer who expresses himself in a minority language, or could it become, in certain circumstances, a threat to his autonomy?
Ukrainianization, terror and famine: Coverage in Lviv'sDiloand the nationalist press of the 1930s
Authors: Shkandrij Myroslav
Published: May 2012

This article looks at the press coverage of Ukrainianization, the Soviet terror, and the famine (Holodomor), particularly in the years 1932–33, focusing on the largest Ukrainian daily outside Soviet Ukraine, the LvivDilo.It compares this coverage to the reporting in the press of the Organization of Ukrainian Nationalists (OUN). It argues that these two years were a turning point in political attitudes. Galician Ukrainians turned away from the Communist Party of Ukraine and support for the OUN began to grow. Ironically, the OUN had not led protests against the famine, but benefited from the lack of a strong response from European governments and international bodies. The article draws on a reading of the Ukrainian press of the 1930s, and on recent research by Polish and Ukrainian scholars.
Identifying the mechanisms underpinning recognition of structured sequences of action
Authors: Williams A.Mark , North Jamie S. , Hope Edward R.
Published: May 2012

We present three experiments to identify the specific information sources that skilled participants use to make recognition judgements when presented with dynamic, structured stimuli. A group of less skilled participants acted as controls. In all experiments, participants were presented with filmed stimuli containing structured action sequences. In a subsequent recognition phase, participants were presented with new and previously seen stimuli and were required to make judgements as to whether or not each sequence had been presented earlier (or were edited versions of earlier sequences). In Experiment 1, skilled participants demonstrated superior sensitivity in recognition when viewing dynamic clips compared with static images and clips where the frames were presented in a nonsequential, randomized manner, implicating the importance of motion information when identifying familiar or unfamiliar sequences. In Experiment 2, we presented normal and mirror-reversed sequences in order to distort access to absolute motion information. Skilled participants demonstrated superior recognition sensitivity, but no significant differences were observed across viewing conditions, leading to the suggestion that skilled participants are more likely to extract relative rather than absolute motion when making such judgements. In Experiment 3, we manipulated relative motion information by occluding several display features for the duration of each film sequence. A significant decrement in performance was reported when centrally located features were occluded compared to those located in more peripheral positions. Findings indicate that skilled participants are particularly sensitive to relative motion information when attempting to identify familiarity in dynamic, visual displays involving interaction between numerous features.
Use of Administrative Data in Efficient Auditing of Hospital-Acquired Surgical Site Infections, New York State 2009–2010
Authors: Haley Valerie B. , Antwerpen Carole Van , Tserenpuntsag Boldtsetseg , Gase Kathleen A. , Hazamy Peggy , Doughty Diana , Tsivitis Marie , Stricof Rachel L.
Published: May 2012

Objective.

To efficiently validate the accuracy of surgical site infection (SSI) data reported to the National Healthcare Safety Network (NHSN) by New York State (NYS) hospitals.

Design.

Validation study.

Setting.

176 NYS hospitals.

Methods.

NYS Department of Health staff validated the data reported to NHSN by review of a stratified sample of medical records from each hospital. The four strata were (1) SSIs reported to NHSN; (2) records with an indication of infection from diagnosis codes in administrative data but not reported to NHSN as SSIs; (3) records with discordant procedure codes in NHSN and state data sets; (4) records not in the other three strata.

Results.

A total of 7,059 surgical charts (6% of the procedures reported by hospitals) were reviewed. In stratum 1, 7% of reported SSIs did not meet the criteria for inclusion in NHSN and were subsequently removed. In stratum 2, 24% of records indicated missed SSIs not reported to NHSN, whereas in strata 3 and 4, only 1% of records indicated missed SSIs; these SSIs were subsequently added to NHSN. Also, in stratum 3, 75% of records were not coded for the correct NHSN procedure. Errors were highest for colon data; the NYS colon SSI rate increased by 7.5% as a result of hospital audits.

Conclusions.

Audits are vital for ensuring the accuracy of hospital-acquired infection (HAI) data so that hospital HAI rates can be fairly compared. Use of administrative data increased the efficiency of identifying problems in hospitals' SSI surveillance that caused SSIs to be unreported and caused errors in denominator data.
Methicillin-Resistant Staphylococcus aureus (MRSA) Nasal Carriage in Residents of Veterans Affairs Long-Term Care Facilities: Role of Antimicrobial Exposure and MRSA Acquisition
Authors: Stone Nimalie D. , Lewis Donna R. , Johnson Theodore M. , Hartney Thomas , Chandler Doris , Byrd-Sellers Johnita , McGowan John E. , Tenover Fred C. , Jernigan John A. , Gaynes Robert P.
Published: May 2012

Objective.

To identify risk factors associated with methicillin-resistant Staphylococcus aureus (MRSA) acquisition in long-term care facility (LTCF) residents.

Design.

Multicenter, prospective cohort followed over 6 months.

Setting.

Three Veterans Affairs (VA) LTCFs.

Participants.

All current and new residents except those with short stay (<2 weeks).

Methods.

MRSA carriage was assessed by serial nares cultures and classified into 3 groups: persistent (all cultures positive), intermittent (at least 1 but not all cultures positive), and noncarrier (no cultures positive). MRSA acquisition was defined by an initial negative culture followed by more than 2 positive cultures with no subsequent negative cultures. Epidemiologic data were collected to identify risk factors, and MRSA isolates were typed by pulsed-field gel electrophoresis (PFGE).

Results.

Among 412 residents at 3 LTCFs, overall MRSA prevalence was 58%, with similar distributions of carriage at all 3 facilities: 20% persistent, 39% intermittent, 41% noncarriers. Of 254 residents with an initial negative swab, 25 (10%) acquired MRSA over the 6 months; rates were similar at all 3 LTCFs, with no clusters evident. Multivariable analysis demonstrated that receipt of systemic antimicrobials during the study was the only significant risk factor for MRSA acquisition (odds ratio, 7.8 [95% confidence interval, 2.1–28.6]; P = .002). MRSA strains from acquisitions were related by PFGE to those from a roommate in 9/25 (36%) cases; 6 of these 9 roommate sources were persistent carriers.

Conclusions.

MRSA colonization prevalence was high at 3 separate VA LTCFs. MRSA acquisition was strongly associated with antimicrobial exposure. Roommate sources were often persistent carriers, but transmission from roommates accounted for only approximately one-third of MRSA acquisitions.
An Outbreak of Extended-Spectrum β-Lactamase–Producing Klebsiella pneumoniae in a Neonatal Intensive Care Unit
Authors: Tamma Pranita D. , Savard Patrice , Pál Tibor , Sonnevend Ágnes , Perl Trish M. , Milstone Aaron M.
Published: May 2012

We present a large outbreak of ESBL-producing Klebsiella pneumoniae in a neonatal intensive care unit that resulted in 31 colonized infants, 10 invasive infections, and 5 attributable deaths over a 5-month period. Although the source of infection was unknown, overcrowding and understaffing appeared to have been aggravating factors.
Efficiency of International Classification of Diseases, Ninth Revision, Billing Code Searches to Identify Emergency Department Visits for Blood or Body Fluid Exposures through a Statewide Multicenter Database
Authors: Rosen Lisa M. , Liu Tao , Merchant Roland C.
Published: May 2012

Background.

Blood and body fluid exposures are frequently evaluated in emergency departments (EDs). However, efficient and effective methods for estimating their incidence are not yet established.

Objective.

Evaluate the efficiency and accuracy of estimating statewide ED visits for blood or body fluid exposures using International Classification of Diseases, Ninth Revision (ICD-9), code searches.

Design.

Secondary analysis of a database of ED visits for blood or body fluid exposure.

Setting.

EDs of 11 civilian hospitals throughout Rhode Island from January 1, 1995, through June 30, 2001.

Patients.

Patients presenting to the ED for possible blood or body fluid exposure were included, as determined by prespecified ICD-9 codes.

Methods.

Positive predictive values (PPVs) were estimated to determine the ability of 10 ICD-9 codes to distinguish ED visits for blood or body fluid exposure from ED visits that were not for blood or body fluid exposure. Recursive partitioning was used to identify an optimal subset of ICD-9 codes for this purpose. Random-effects logistic regression modeling was used to examine variations in ICD-9 coding practices and styles across hospitals. Cluster analysis was used to assess whether the choice of ICD-9 codes was similar across hospitals.

Results.

The PPV for the original 10 ICD-9 codes was 74.4% (95% confidence interval [CI], 73.2%–75.7%), whereas the recursive partitioning analysis identified a subset of 5 ICD-9 codes with a PPV of 89.9% (95% CI, 88.9%–90.8%) and a misclassification rate of 10.1%. The ability, efficiency, and use of the ICD-9 codes to distinguish types of ED visits varied across hospitals.

Conclusions.

Although an accurate subset of ICD-9 codes could be identified, variations across hospitals related to hospital coding style, efficiency, and accuracy greatly affected estimates of the number of ED visits for blood or body fluid exposure.
Healthcare-Associated Infection and Hospital Readmission
Authors: Emerson Carley B. , Eyzaguirre Lindsay M. , Albrecht Jennifer S. , Comer Angela C. , Harris Anthony D. , Furuno Jon P.
Published: May 2012

Objective.

Hospital readmissions are a current target of initiatives to reduce healthcare costs. This study quantified the association between having a clinical culture positive for 1 of 3 prevalent hospital-associated organisms and time to hospital readmission.

Design.

Retrospective cohort study.

Patients and Setting.

Adults admitted to an academic, tertiary care referral center from January 1, 2001, through December 31, 2008.

Methods.

The primary exposure of interest was a clinical culture positive for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), or Clostridium difficile obtained more than 48 hours after hospital admission during the index hospital stay. The primary outcome of interest was time to readmission to the index facility. Multivariable Cox proportional hazards models were used to model the adjusted association between positive clinical culture result and time to readmission and to calculate hazard ratios (HRs) and 95% confidence intervals (CIs).

Results.

Among 136,513 index admissions, the prevalence of hospital-associated positive clinical culture result for 1 of the 3 organisms of interest was 3%, and 35% of patients were readmitted to the index facility within 1 year after discharge. Patients with a positive clinical culture obtained more than 48 hours after hospital admission had an increased hazard of readmission (HR, 1.40; 95% CI, 1.33–1.46) after adjusting for age, sex, index admission length of stay, intensive care unit stay, Charlson comorbidity index, and year of hospital admission.

Conclusions.

Patients with healthcare-associated infections may be at increased risk of hospital readmission. These findings may be used to impact health outcomes after discharge from the hospital and to encourage better infection prevention efforts.
Prospective Nationwide Surveillance of Surgical Site Infections after Gastric Surgery and Risk Factor Analysis in the Korean Nosocomial Infections Surveillance System (KONIS)
Authors: Kim Eu Suk , Kim Hong Bin , Song Kyoung-Ho , Kim Young Keun , Kim, Hyung-Ho , Jin Hye Young , Jeong Sun Young , Sung Joohon , Cho Yong Kyun , Lee Yeong-Seon , Oh Hee-Bok , Kim Eui-Chong , Kim June Myung , Choi Tae Yeol , Choi Hee Jung , Kim Hyo Youl ,   for the Korean Nosocomial Infections Surveillance System (KONIS)
Published: May 2012

Objective.

To evaluate the risk factors for surgical site infection (SSI) after gastric surgery in patients in Korea.

Design.

A nationwide prospective multicenter study.

Setting.

Twenty university-affiliated hospitals in Korea.

Methods.

The Korean Nosocomial Infections Surveillance System (KONIS), a Web-based system, was developed. Patients in 20 Korean hospitals from 2007 to 2009 were prospectively monitored for SSI for up to 30 days after gastric surgery. Demographic data, hospital characteristics, and potential perioperative risk factors were collected and analyzed, using multivariate logistic regression models.

Results.

Of the 4,238 case patients monitored, 64.9% (2,752) were male, and mean age (±SD) was 58.8 (±12.3) years. The SSI rates were 2.92, 6.45, and 10.87 per 100 operations for the National Nosocomial Infections Surveillance system risk index categories of 0, 1, and 2 or 3, respectively. The majority (69.4%) of the SSIs observed were organ or space SSIs. The most frequently isolated microorganisms were Staphylococcus aureus and Klebsiella pneumoniae. Male sex (odds ratio [OR], 1.67 [95% confidence interval (CI), 1.09–2.58]), increased operation time (1.20 [1.07–1.34] per 1-hour increase), reoperation (7.27 [3.68–14.38]), combined multiple procedures (1.79 [1.13–2.83]), prophylactic administration of the first antibiotic dose after skin incision (3.00 [1.09–8.23]), and prolonged duration (≥7 days) of surgical antibiotic prophylaxis (SAP; 2.70 [1.26–5.64]) were independently associated with increased risk of SSI.

Conclusions.

Male sex, inappropriate SAP, and operation-related variables are independent risk factors for SSI after gastric surgery.
Translational motion of an atom in a weakly driven fiber-Bragg-grating cavity
Authors: Kien Fam Le , Hakuta K
Published: May 2012

We study the translational motion of an atom in the vicinity of a weakly driven nanofiber with two fiber-Bragg-grating mirrors. We find that the spatial dependences of the force, the friction coefficients and the momentum diffusion are very complicated due to the evanescent-wave nature of the atom–field coupling as well as the effect of the van der Waals potential. We show that the time development of the mean number of photons in the cavity closely follows the translational motion of the atom through the nodes and antinodes of the fiber-guided cavity standing-wave field even though the cavity finesse is moderate, the cavity is long and the probe field is weak.
Synthesis of AgCl/Ag nanopowder and its application in photodegradation of methylene blue
Authors: Nguyen Van Khanh , Vu Thi Ha
Published: May 2012

We present the synthesis of AgCl/Ag and investigate its structural and optical properties as well as applying this product to the photodegradation of methylene blue (MB). The significant result is to almost photodegrade MB after 120 mins under visible light. The development of such photocatalysts may be considered a breakthrough in large-scale utilization of solar energy towards environmental needs. The technology for preparing AgCl/Ag was elaborated. The product can be recycled after use.
A novel nanofiber Cur-loaded polylactic acid constructed by electrospinning
Authors: Trang Mai Thi Thu , Thuy Nguyen Thi Thu , Duong Le Quang , Ngoan Nguyen Thi , Cham Ba Thi , Binh Nguyen Hai , Hoa Phan Thi Bich , Lam Tran Dai , Nguyen Xuan Phuc , Seo Park Jun
Published: May 2012

Curcumin (Cur), extracted from the Curcuma longa L. plant, is well known for its anti-tumor, anti-oxidant, anti-inflammatory and anti-bacterial properties. Nanofiber mats of polylactic acid (PLA) loading Cur (5 wt%) were fabricated by electrospinning (e-spinning). Morphology and structure of the fibers were characterized by field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FTIR) spectroscopy, respectively. The diameters of the obtained fibers varied from 200 to 300 nm. The release capacity of curcumin from curcumin-loaded PLA fibers was investigated in phosphate buffer saline (PBS) containing ethanol. After 24 h, 50% of the curcumin was released from curcumin-loaded PLA fibers. These results of electrospun (e-spun) fibers exhibit the potential for biomedical application.
Sol–gel hydrothermal synthesis of strontium hexaferrite nanoparticles and the relation between their crystal structure and high coercivity properties
Authors: Dang Thi Minh Hue , Trinh Viet Dung , Bui Doan Huan , Phan Manh Huong , Huynh Dang Chinh
Published: May 2012

Hard magnetic strontium hexaferrite SrFe
12
O
19 nanoparticles were synthesized by the sol–gel hydrothermal method. The factors affecting the synthesized process, such as the mole proportion of the reactants, pH, temperature, the hydrothermal conditions and the calcination process, have been investigated. The crystal structures of these materials were refined by Rietveld method. The obtained materials have single crystal phase, equal nano-size, plate shape and high anisotropy. The high magnetic coercivity of 6.3 kOe with the magnetization at 11.1 kOe of 66 emu 
g
−1 at room temperature was observed for the strontium hexaferrite nanoparticles. For other nanoparticles (SrLn

x

Fe
12-x

O
19 and SrFe
12
O
19/CoFe
2
O
4) synthesized on the basis of SrFe
12
O
19 the complex completion of the crystal structure distortion and the interaction between magnetic phases were observed.
Preparation of metal nanoparticles for surface enhanced Raman scattering by laser ablation method
Authors: Nguyen The Binh , Thu Vu Thi Khanh , Nguyen Quang Dong , Nguyen Thanh Dinh , Nguyen The An , Trinh Thi Hue
Published: May 2012

Gold, silver and copper nanoparticles were prepared in clean and biologically-friendly liquids by laser ablation. The average size of nanoparticles ranges from 3 to 30 nm. These nanoparticles were used to fabricate nanostructured substrates for surface enhanced Raman scattering (SERS) measurement. Raman spectra were measured by a Micro-Raman spectrophotometer. The results show that gold, silver and copper nanoparticle substrates fabricated by our method are effective for SERS studies. SERS was also obtained when using gold, silver and copper nanoparticle colloid prepared by laser ablation.
Synthesis and optical properties of water soluble CdSe/CdS quantum dots for biological applications
Authors: Chu Viet Ha , Lien Nghiem Thi Ha , Le Tien Ha , Lam Vu Dinh , Nhung Tran Hong , Lien Vu Thi Kim
Published: May 2012

Water soluble CdSe/CdS quantum dots (QDs) have been synthesized directly in aqueous solution with sodium citrate as surfactant agent. The QDs are mono-dispersed in water and have strong luminescent emission intensity under excitation of ultraviolet light. The emission maxima of the QDs can be tuned in a wider range from 555 to 615 nm in water by changing synthesis conditions. The result of the synthesis of water-soluble CdSe and CdSe/CdS QDs shows the high quality of the QDs with the quite narrow luminescence emission band and photostability. The results show the strongest intensity of photoluminescence emission in media with pH value at about from 8–8.5, which are pH physiological environments. The luminescence intensity increases when the QDs are coated with a polyethylene glycol (PEG) or bovine serum albumin (BSA) protein layer, the lifetime also increases.