Three dimensional adhesion model for arbitrary rough surfaces

We present a 3D adhesion model based on the JKR theory applied locally for all contacting asperity couple and the calculations account the van der Waals interaction beside the externally applied force. Thus, equilibrium of the system is determined by an extremum in the free total energy and subsequently the contact and the adhesion parameters are computed for that particular position. The model estimates the adhesion of contacting arbitrary rough surfaces taking into account that asperities deform according to one of the three deformation regimes (elastic, elasto-plastic and plastic). The deformation of the contacting asperities is determined by the material properties, the asperity characteristics as well as the surface topography. Results show that even outside the bonding regime the specific bonding energy is still high enough to cause adhesive problems for microstructures

Multifunctional Tool for Expanding AFM-Based Applications

A multifunctional tool which expands the application field of atomic force microscope-based surface modification is presented. The AFM-probe can be used for surface modification and in-situ characterization at the same time, due to a special configuration with two cantilevers. Various applications from different fields are presented, which were carried out with one and the same tool: in-situ characterization of wear generated with and without local lubrication (tribology), fountain-pen lithography in which material is deposited or removed (physical chemistry), and electrochemical metal deposition (electrochemistry)

Phytoplankton composition and abundance in the coastal waters of the Datça and Bozburun Peninsulas, south-eastern Aegean Sea (Turkey)

A study of the abundance and composition of microphytoplankton was carried out in marine areas of the Datça and Bozburun Peninsulas between the years 2002 and 2004. Simultaneously measured physical (salinity, temperature, secchi disc) and chemical parameters (nutrients, chl-a, dissolved oxygen) were assessed together with microphytoplankton data. Seawater and plankton net samples were taken from 63 stations during 6 sampling periods. A total of 132 taxa belonging to 3 taxonomic classes was reported and a checklist of microphytoplankton was prepared for this study area. Average nutrient values in surface water ranged from 0.01 to 1.19 µM for NO3+NO2–N, from 0.01 to 0.69 µM for PO4–P and from 0.50 to 5.31 µM for SiO2–Si and chl–a values were between 0.19 and 0.68 µg l–1 throughout the study area. The highest number of microphytoplankton cells reached 5400 cells l–1 and dinoflagellate Prorocentrum micans reached 1500 cells l–1 while diatom Thalassionema nitzschioides reached 700 cells l–1. Dinoflagellates showed a more homogeneous distribution in a wider area than diatoms. The dinoflagellate abundance increased in areas close to the fish farms due to the amount of nutrients originating there. Spatial changes in phytoplankton composition observed in this marine area revealed that phytoplankton are very sensitive to ecosystem changes. The study area could generally be defined as oligotrophic in terms of trophic status depending on the nutrient and chl–a concentrations. Moreover, very low cell abundance and high species richness observed in this area also reflect typical characteristics of oligotrophic waters

A prolonged red tide of Heterocapsa triquetra (Ehrenberg) F. Stein (Dinophyceae) and phytoplankton succession in a eutrophic estuary in Turkey

A prolonged red tide of Heterocapsa triquetra and phytoplankton succession were investigated in a eutrophic estuary (Golden Horn) for a year. Runoff following the rainfall in winter supplied high amounts of nutrients and also created a mesohaline frontal zone in the middle and upper estuary. Red tide of H. triquetra was first observed with an orange-brownish water discoloration at the upper estuary in January. Highest cell density of H. triquetra was 2.7×106 cells l-1 in January and reached to 19.2×106 cells l-1 in April. Successive blooms continued with dinoflagellate Prorocentrum minimum in May and phytoflagellates Eutreptiella marina and Fibrocapsa sp. in summer. High chl-a and dissolved oxygen were measured in the spring depending on algal biomass. Findings indicate that H. triquetra might be adapted to moderate salinity and low temperatures and red tide events should be considered as a response to increasing eutrophication due to high amounts of nutrients. Eutrophication can lead to harmful algal blooms for this area in the near future

Quasiparticle band structure of the almost-gapless transition-metal-based Heusler semiconductors

Transition-metal-based Heusler semiconductors are promising materials for a variety of applications ranging from spintronics to thermoelectricity. Employing the $GW$ approximation within the framework of the FLAPW method, we study the quasi-particle band structure of a number of such compounds being almost gapless semiconductors. We find that in contrast to the \textit{sp}-electron based semiconductors such as Si and GaAs, in these systems the many-body corrections have a minimal effect on the electronic band structure and the energy band gap increases by less than 0.2~eV, which makes the starting point density functional theory (DFT) a good approximation for the description of electronic and optical properties of these materials. Furthermore, the band gap can be tuned either by the variation of the lattice parameter or by the substitution of the \emph{sp}-chemical element

The Impact of the Economic Crisis on Women's Economic Empowerment

This paper argues that a systematic gender analysis of the current crisis is critical to develop viable solutions and for furthering the trend toward gender equality. It analyses the short- and long-term impact of the current economic crisis with a focus on developing countries. It identifies the multiple channels and transmission mechanisms through which the global economic crisis has affected women's lives and explores different areas where the burden of the crisis falls on poor women, using current indications, micro-level evidence and lessons learned from previous crises. The paper shows that the magnitude and types of effects are context-specific: they are likely to vary across countries, sectors, households and among women, depending on the economic, demographic and social circumstances. In the short run, many women are expected to lose their jobs, particularly those working on the export sectors and/or holding flexible jobs. At the same time, a fall in the supply of micro-credit is expected to result in a decrease in earnings among self-employed women workers in trade, agriculture and other sectors. Additionally, there will likely be an increase in the amount of unpaid work that women do to support their families. In the long-run, it is expected that an increase in girls' dropout rate from school to compensate for their families' loss of income will deteriorate women's future socioeconomic opportunities. In addition, an increase in the level of violence against women, combined with limited access to health and other support services as a result of public expenditure cuts and lower aid receipts, complete the dim picture of the gendered impact of the crisis in developing countries. The paper concludes that it is essential to implement mechanisms to mitigate the negative effects of the crisis on women, in order to ensure that the gains in women's empowerment and gender equality in the last few decades are not put in danger. Furthermore, it is argued that the crisis can be used as a unique opportunity to change power structures and make economic and social policies more gender-aware and move toward creating a more gender-equal society and economic system. To that end, civil society involvement to monitor the gender effects of the crisis in the short and medium term, as well as government-led (and donor supported) gender-aware response packages will be essential.

Meningkatkan Prestasi Belajar Siswa Melalui Penerapan Model Pembelajaran Kooperatif Tipe Think-Pair Share Alam Pembelajaran IPS Di Kelas IV SDN Inpres Mayayap

Masalah pada penelitian ini adalah rendahnya prestasi belajar siswa pada pelajaran IPS kelas IV khususnya pada materi Aktivitas ekonomi yang berkaitan dengan sumber daya alam. Rendahnya prestasi belajar disebabkan kurangnya perhatian siswa selama pembelajaran berlangsung karena siswa yang bertanya sangat kurang, demikian halnya bila guru yang bertanya kepada siswa, sehingga umpan Balik tidak terjadi sama sekali. Padahal umpan Balik dalam pembelajaran sangat diperlukan untuk menumbuhkan sifat keingin-tahuan siswa dalam memotivasi siswa untuk lebih rajin menggali informasi melalui bacaan. Kurangnya perhatian siswa dapat mengakibatkan rendahnya prestasi belajar siswa. Hal tersebut disebabkan karena guru dalam melakukan pembelajaran kurang menggunakan alat peraga sehingga siswa merasa jenuh dengan proses pembelajaran yang digunakan. Oleh karena itu, peneliti melakukan penelitian tindakan kelas yang rancangan penelitiannya mengacu pada model Kemmis dan Mc. Taggart yang dilakukan dalam dua siklus. Informan penelitian sebanyak empat orang dengan kualifikasi semua siswa yang berkemampuan rendah. Jenis data yang diperoleh adalah aktivitas guru dan siswa di kelas dan hasil belajar siswa. Data aktivitas guru dan siswa dalam kegiatan pembelajaran diperoleh dengan lembar observasi dan data prestasi belajar diperoleh dengan tes individu. Data-data tersebut dianalisis dengan teknik prosentase. Berdasarkan hasil penelitian menunjukkan bahwa aktivitas guru dan siswa mengalami peningkatan yang cukup berarti dari siklus I ke siklus II dan untuk analisis tes akhir tindakan dari siklus I ke siklus II terjadi peningkatan belajar klasikal sebesar 36% yaitu dari 64% pada siklus I menjadi 100% pada siklus II. Berdasarkan hasil tersebut dapat disimpulkan bahwa dengan model pembelajaran kooperatif tipe Think Pair Share dapat meningkatkan Prestasi belajar siswa pada mata pelajaran IPS di kelas IV SD Inpres Mayayap Pada materi Aktivitas ekonomi yang berkaitan dengan sumber daya alam

Local Stellar Kinematics from RAVE data - VII. Metallicity Gradients from Red Clump Stars

We investigate the Milky Way Galaxy's radial and vertical metallicity gradients using a sample of 47,406 red clump stars from the RAVE DR4. This sample is more than twice the size of the largest sample in the literature investigating radial and vertical metallicity gradients. The absolute magnitude of Groenewegen (2008) is used to determine distances to our sample stars. The resulting distances agree with the RAVE DR4 distances Binney et al. (2014) of the same stars. Our photometric method also provides distances to 6185 stars that are not assigned a distance in RAVE DR4. The metallicity gradients are calculated with their current orbital positions ($R_{gc}$ and $Z$) and with their orbital properties (mean Galactocentric distance, $R_{m}$ and $z_{max}$), as a function of the distance to the Galactic plane: d[Fe/H]/d$R_{gc}=$-$0.047\pm0.003$ dex/kpc for $0\leq |Z|\leq0.5$ kpc and d[Fe/H]/d$R_m=$-$0.025\pm0.002$ dex/kpc for $0\leq z_{max}\leq0.5$ kpc. This reaffirms the radial metallicity gradient in the thin disc but highlights that gradients are sensitive to the selection effects caused by the difference between $R_{gc}$ and $R_{m}$. The radial gradient is flat in the distance interval 0.5-1 kpc from the plane and then becomes positive greater than 1 kpc from the plane. The radial metallicity gradients are also eccentricity dependent. We showed that d[Fe/H]/d$R_m=$-$0.089\pm0.010$, -$0.073\pm0.007$, -$0.053\pm0.004$ and -$0.044\pm0.002$ dex/kpc for $e_p\leq0.05$, $e_p\leq0.07$, $e_p\leq0.10$ and $e_p\leq0.20$ sub-samples, respectively, in the distance interval $0\leq z_{max}\leq0.5$ kpc. Similar trend is found for vertical metallicity gradients. Both the radial and vertical metallicity gradients are found to become shallower as the eccentricity of the sample increases. These findings can be used to constrain different formation scenarios of the thick and thin discs.Comment: 18 pages, including 16 figures and 6 tables, accepted for publication in PAS