Pullulan for advanced sustainable body- And skin-contact applications

The present review had the aim of describing the methodologies of synthesis and properties of biobased pullulan, a microbial polysaccharide investigated in the last decade because of its interesting potentialities in several applications. After describing the implications of pullulan in nano-technology, biodegradation, compatibility with body and skin, and sustainability, the current applications of pullulan are described, with the aim of assessing the potentialities of this biopolymer in the biomedical, personal care, and cosmetic sector, especially in applications in contact with skin

Pick, List, Evaluate, Activate, Supply, End (PLEASE) Strategy: Teaching Writing Viewed from Students’ Self-Esteem (An Experimental Research at the Tenth Grade of SMAN 1 Tangen in the Academic Year of 2016/2017)

Penelitian ini bertujuan untuk mengungkap apakah: (1) Strategi PLEASE lebih efektif daripada strategi RAFT untuk mengajar menulis; (2) Siswa yang memiliki penghargaan diri tinggi memiliki keterampilan menulis yang lebih baik daripada siswa yang memiliki penghargaan diri rendah; dan (3) Terdapat interaksi antara strategi mengajar dan penghargaan diri siswa dalam pengajaran menulis. Penelitian eksperimen ini dilaksanakan di kelas X SMAN 1 Tangen pada tahun akademik 2016/2017. Peneliti mengambil dua kelas dari kelas X MIPA sebagai sampel dengan menggunakan sampling acak kelompok. Satu kelas, kelas eksperimen, diajar dengan menggunakan strategi PLEASE. Kelas yang lain, kelas kontrol, diajar dengan menggunakan strategi RAFT. Tiap kelas dibagi menjadi dua kelompok yang terdiri dari siswa yang memiliki penghargaan diri tinggi dan siswa yang memiliki penghargaan diri rendah. Untuk mengumpulkan data, tes menulis dan kuesioner penghargaan diri dipergunakan. Data kemudian dianalisis dengan menggunakan Analisis Multifaktor Varians ANOVA 2 x 2 dan uji Tukey. Sebelum melakukan uji ANOVA, uji prasyarat seperti uji normalitas dan homogenitas dilakukan terlebih dahulu. Temuan penelitian ini dapat dinyatakan sebagai berikut: (1) Strategi PLEASE lebih efektif daripada strategi RAFT untuk mengajar menulis; (2) Siswa yang memiliki penghargaan diri tinggi memiliki keterampilan menulis yang lebih baik daripada siswa yang memiliki penghargaan diri rendah; dan (3) Terdapat interaksi antara strategi mengajar dan penghargaan diri siswa dalam pengajaran menulis. Temuan ini memberikan implikasi bahwa strategi PLEASE adalah sebuah strategi yang efektif untuk mengajar menulis kepada siswa kelas X SMAN 1 Tangen. Penelitian lebih lanjut dianjurkan untuk mengoptimalkan penggunaan strategi PLEASE dengan cara mengkombinasikannya dengan media ajar yang menarik. Penggunaan variabel atributif lainnya juga dianjurkan. Kata Kunci: desain faktorial, keterampilan menulis, penghargaan diri siswa, strategi PLEASE, strategi RAFT. This research is aimed to reveal whether: (1) PLEASE strategy is more effective than RAFT strategy to teach writing; (2) Students having high self-esteem have better writing skill than those having low self-esteem; and (3) There is an interaction between the teaching strategies and the students’ self-esteem in teaching writing. This experimental research was conducted at the tenth grade of SMAN 1 Tangen in the academic year of 2016/2017. The researcher took two classes from the tenth grade natural sciences classes as the sample by using cluster random sampling. One class, experimental class, was taught by using PLEASE strategy. Another class, control class, was taught by using RAFT strategy. Each class was divided into two groups consisting of students having high self-esteem and those having low self-esteem. To collect the data, writing test and self-esteem questionnaire were employed. The data were, then, analyzed by using Multifactor Analysis of Variance ANOVA 2 x 2 and Tukey test. Before conducting the ANOVA test, pre-requisite tests such as normality and homogeneity test were done. The findings of this research can be stated as follows: (1) PLEASE strategy is more effective than RAFT strategy to teach writing; (2) Students having high self-esteem have better writing skill than those having low self-esteem; and (3) There is an interaction between teaching strategies and students’ self-esteem in teaching writing. It implies that PLEASE strategy is an effective strategy to teach writing to the tenth grade students of SMAN 1 Tangen. Further researches are encouraged to optimize the use of PLEASE strategy by combining it with interesting teaching media. The use of other attributive variables are also encouraged. Keywords: factorial design, PLEASE strategy, RAFT strategy, students’ self-esteem, writing skill

Improving transferability of introduced species' distribution models: new tools to forecast the spread of a highly invasive seaweed

Extent: 13 p.The utility of species distribution models for applications in invasion and global change biology is critically dependent on their transferability between regions or points in time, respectively. We introduce two methods that aim to improve the transferability of presence-only models: density-based occurrence thinning and performance-based predictor selection. We evaluate the effect of these methods along with the impact of the choice of model complexity and geographic background on the transferability of a species distribution model between geographic regions. Our multifactorial experiment focuses on the notorious invasive seaweed Caulerpa cylindracea (previously Caulerpa racemosa var. cylindracea) and uses Maxent, a commonly used presence-only modeling technique. We show that model transferability is markedly improved by appropriate predictor selection, with occurrence thinning, model complexity and background choice having relatively minor effects. The data shows that, if available, occurrence records from the native and invaded regions should be combined as this leads to models with high predictive power while reducing the sensitivity to choices made in the modeling process. The inferred distribution model of Caulerpa cylindracea shows the potential for this species to further spread along the coasts of Western Europe, western Africa and the south coast of Australia.Heroen Verbruggen, Lennert Tyberghein, Gareth S. Belton, Frederic Mineur, Alexander Jueterbock, Galice Hoarau, C. Frederico D. Gurgel, Olivier De Clerc

Quantum interference and the formation of the proximity effect in chaotic normal-metal/superconducting structures

We discuss a number of basic physical mechanisms relevant to the formation of the proximity effect in superconductor/normal metal (SN) systems. Specifically, we review why the proximity effect sharply discriminates between systems with integrable and chaotic dynamics, respectively, and how this feature can be incorporated into theories of SN systems. Turning to less well investigated terrain, we discuss the impact of quantum diffractive scattering on the structure of the density of states in the normal region. We consider ballistic systems weakly disordered by pointlike impurities as a test case and demonstrate that diffractive processes akin to normal metal weak localization lead to the formation of a hard spectral gap -- a hallmark of SN systems with chaotic dynamics. Turning to the more difficult case of clean systems with chaotic boundary scattering, we argue that semiclassical approaches, based on classifications in terms of classical trajectories, cannot explain the gap phenomenon. Employing an alternative formalism based on elements of quasiclassics and the ballistic $\sigma$-model, we demonstrate that the inverse of the so-called Ehrenfest time is the relevant energy scale in this context. We discuss some fundamental difficulties related to the formulation of low energy theories of mesoscopic chaotic systems in general and how they prevent us from analysing the gap structure in a rigorous manner. Given these difficulties, we argue that the proximity effect represents a basic and challenging test phenomenon for theories of quantum chaotic systems.Comment: 21 pages (two-column), 6 figures; references adde

Energy dependent counting statistics in diffusive superconducting tunnel junctions

We present an investigation of the energy dependence of the full charge counting statistics in diffusive normal-insulating-normal-insulating-superconducting junctions. It is found that the current in general is transported via a correlated transfer of pairs of electrons. Only in the case of strongly asymmetric tunnel barriers or energies much larger than the Thouless energy is the pair transfer uncorrelated. The second cumulant, the noise, is found to depend strongly on the applied voltage and temperature. For a junction resistance dominated by the tunnel barrier to the normal reservoir, the differential shot noise shows a double peak feature at voltages of the order of the Thouless energy, a signature of an ensemble averaged electron-hole resonance.Comment: 8 pages, 5 figure

Quantum Disorder and Quantum Chaos in Andreev Billiards

We investigate the crossover from the semiclassical to the quantum description of electron energy states in a chaotic metal grain connected to a superconductor. We consider the influence of scattering off point impurities (quantum disorder) and of quantum diffraction (quantum chaos) on the electron density of states. We show that both the quantum disorder and the quantum chaos open a gap near the Fermi energy. The size of the gap is determined by the mean free time in disordered systems and by the Ehrenfest time in clean chaotic systems. Particularly, if both times become infinitely large, the density of states is gapless, and if either of these times becomes shorter than the electron escape time, the density of states is described by random matrix theory. Using the Usadel equation, we also study the density of states in a grain connected to a superconductor by a diffusive contact.Comment: 20 pages, 10 figure

Quantum nondemolition measurement of mechanical motion quanta

The fields of opto- and electromechanics have facilitated numerous advances in the areas of precision measurement and sensing, ultimately driving the studies of mechanical systems into the quantum regime. To date, however, the quantization of the mechanical motion and the associated quantum jumps between phonon states remains elusive. For optomechanical systems, the coupling to the environment was shown to preclude the detection of the mechanical mode occupation, unless strong single photon optomechanical coupling is achieved. Here, we propose and analyse an electromechanical setup, which allows to overcome this limitation and resolve the energy levels of a mechanical oscillator. We find that the heating of the membrane, caused by the interaction with the environment and unwanted couplings, can be suppressed for carefully designed electromechanical systems. The results suggest that phonon number measurement is within reach for modern electromechanical setups.Comment: 8 pages, 5 figures plus 24 pages, 11 figures supplemental materia

Quantum Measurement Theory in Gravitational-Wave Detectors

The fast progress in improving the sensitivity of the gravitational-wave (GW) detectors, we all have witnessed in the recent years, has propelled the scientific community to the point, when quantum behaviour of such immense measurement devices as kilometer-long interferometers starts to matter. The time, when their sensitivity will be mainly limited by the quantum noise of light is round the corner, and finding the ways to reduce it will become a necessity. Therefore, the primary goal we pursued in this review was to familiarize a broad spectrum of readers with the theory of quantum measurements in the very form it finds application in the area of gravitational-wave detection. We focus on how quantum noise arises in gravitational-wave interferometers and what limitations it imposes on the achievable sensitivity. We start from the very basic concepts and gradually advance to the general linear quantum measurement theory and its application to the calculation of quantum noise in the contemporary and planned interferometric detectors of gravitational radiation of the first and second generation. Special attention is paid to the concept of Standard Quantum Limit and the methods of its surmounting.Comment: 147 pages, 46 figures, 1 table. Published in Living Reviews in Relativit

Kondo effect in coupled quantum dots: a Non-crossing approximation study

The out-of-equilibrium transport properties of a double quantum dot system in the Kondo regime are studied theoretically by means of a two-impurity Anderson Hamiltonian with inter-impurity hopping. The Hamiltonian, formulated in slave-boson language, is solved by means of a generalization of the non-crossing approximation (NCA) to the present problem. We provide benchmark calculations of the predictions of the NCA for the linear and nonlinear transport properties of coupled quantum dots in the Kondo regime. We give a series of predictions that can be observed experimentally in linear and nonlinear transport measurements through coupled quantum dots. Importantly, it is demonstrated that measurements of the differential conductance ${\cal G}=dI/dV$, for the appropriate values of voltages and inter-dot tunneling couplings, can give a direct observation of the coherent superposition between the many-body Kondo states of each dot. This coherence can be also detected in the linear transport through the system: the curve linear conductance vs temperature is non-monotonic, with a maximum at a temperature $T^*$ characterizing quantum coherence between both Kondo states.Comment: 20 pages, 17 figure

Dynamical decoupling and noise spectroscopy with a superconducting flux qubit

The characterization and mitigation of decoherence in natural and artificial two-level systems (qubits) is fundamental to quantum information science and its applications. Decoherence of a quantum superposition state arises from the interaction between the constituent system and the uncontrolled degrees of freedom in its environment. Within the standard Bloch-Redfield picture of two-level system dynamics, qubit decoherence is characterized by two rates: a longitudinal relaxation rate Gamma1 due to the exchange of energy with the environment, and a transverse relaxation rate Gamma2 = Gamma1/2 + Gamma_phi which contains the pure dephasing rate Gamma_phi. Irreversible energy relaxation can only be mitigated by reducing the amount of environmental noise, reducing the qubit's internal sensitivity to that noise, or through multi-qubit encoding and error correction protocols (which already presume ultra-low error rates). In contrast, dephasing is in principle reversible and can be refocused dynamically through the application of coherent control pulse methods. In this work we demonstrate how dynamical-decoupling techniques can moderate the dephasing effects of low-frequency noise on a superconducting qubit with energy-relaxation time T1 = 1/Gamma1 = 12 us. Using the CPMG sequence with up to 200 pi-pulses, we demonstrate a 50-fold improvement in the transverse relaxation time T2 over its baseline value. We observe relaxation-limited times T2(CPMG) = 23 us = 2 T1 resulting from CPMG-mediated Gaussian pure-dephasing times in apparent excess of 100 us. We leverage the filtering property of this sequence in conjunction with Rabi and energy relaxation measurements to facilitate the spectroscopy and reconstruction of the environmental noise power spectral density.Comment: 21 pages (incl. 11-page appendix); 4 (+7) figure