Intensity dependences of the nonlinear optical excitation of plasmons in graphene

Recently, we demonstrated an all-optical coupling scheme for plasmons, which takes advantage of the intrinsic nonlinear optical response of graphene. Frequency mixing using free-space, visible light pulses generates surface plasmons in a planar graphene sample, where the phase matching condition can define both the wavevector and energy of surface waves and intraband transitions. Here, we also show that the plasmon generation process is strongly intensity-dependent, with resonance features washed out for absorbed pulse fluences greater than 0.1 J m−2. This implies a subtle interplay between the nonlinear generation process and sample heating. We discuss these effects in terms of a non-equilibrium charge distribution using a two-temperature model.Peer ReviewedPostprint (author's final draft

Prinsip Kehati-hatian Pejabat Pembuat Akta Tanah dalam Pengurusan Peralihan Tanah “Letter C”

Penulisan jurnal ini membahas mengenai salah satu permasalahan tentang Prinsip Kehati-Hatiaan Pejabat Pembuat Akta Tanah Dalam Pengurusan Peralihan Tanah “Letter C”. Permasalahan yang muncul adalah Prinsip Kehatian-hatian PPAT hanya dijelaskan dalam Pasal 22 PP No. 37 Tahun 1998 bahwa Akta PPAT harus dibacakan/dijelaskan isinya kepada para pihak dengan dihadiri oleh sekurang-kurangnya 2 (dua) orang saksi sebelum ditandatangani seketika itu juga oleh para pihak, saksi-saksi dan PPAT. Sementara dalam pengurusan peralihan tanah Letter C seharus-nya seorang PPAT tidak hanya memastikan bahwa para pihak menghadap dengan PPAT sebagai Pejabat yang membacakan dan menjelaskan akta akan tetapi sesuai prinsip kehati-hatian PPAT dapat menghindari dan mencegah terjadinya kesalahan yang menyebabkan munculnya permasalahan dalam pengurusan peralihan Letter C. karena dalam praktek pengurusan Letter C, PPAT tidak membacakan dan menjelaskan isi akta yang mana para pihak tidak hadir di hadapan PPAT. Sehingga PPAT tidak hati-hati dalam menjalankan jabatannya. Selain itu dalam Pasal 23 Ayat (1) dijelaskan mengenai prinsip kehati-hatian yakni “PPAT dilarang membuat akta, apabila PPAT sendiri, suami atau istrinya, keluarganya sedarah atau semenda, dalam garis lurus tanpa pembatasan derajat dan dalam garis ke samping sampai derajat kedua, menjadi pihak dalam perbuatan hukum yang bersangkutan, baik dengan cara bertindak sendiri maupun melalui kuasa, atau menjadi kuasa dari pihak lain.” Sementara dalam praktiknya PPAT dalam pengurusan Letter C menjadi pihak dengan membuat kuasa pengurusan Letter C. Tujuan penelitian ini untuk Mengkaji dan menganalisis kedudukan dan kekuatan hukum Letter C sebagai alat bukti kepemilikan tanah dan Mengkaji dan Menganalisis bentuk pelaksanaan prinsip kehati-hatiaan PPAT dalam pengurusan peralihan tanah Letter C. dengan menggunakan metode penelitian pada jenis adalah penelitian hukum normatif. Penelitian hukum normatif adalah memecahkan masalah hukum secara normatif yang pada dasarnya bertumpu pada analisa dan mendalam terhadap bahan-bahan pustaka dan dokumen-dokumen hukum yang relevan dengan permasalahan hukum yang dikaji. Penelitian melalui metode normatif dalam penulisan ini adalah Prinsip Kehati-Hatiaan Pejabat Pembuat Akta Tanah Dalam Pengurusan Peralihan Tanah “Letter C”

Reinforcing Value of Information Technical Report No. 65-1

Psychology experiment to show if information is reinforcing and if negative discriminative stimulus is both positively and negatively reinforcin

Hot phonon decay in supported and suspended exfoliated graphene

Near infrared pump-probe spectroscopy has been used to measure the ultrafast dynamics of photoexcited charge carriers in monolayer and multilayer graphene. We observe two decay processes occurring on 100 fs and 2 ps timescales. The first is attributed to the rapid electron-phonon thermalisation in the system. The second timescale is found to be due to the slow decay of hot phonons. Using a simple theoretical model we calculate the hot phonon decay rate and show that it is significantly faster in monolayer flakes than in multilayer ones. In contrast to recent claims, we show that this enhanced decay rate is not due to the coupling to substrate phonons, since we have also seen the same effect in suspended flakes. Possible intrinsic decay mechanisms that could cause such an effect are discussed.Comment: 4 pages, 3 figure

Non-linear resistivity and heat dissipation in monolayer graphene

We have experimentally studied the nonlinear nature of electrical conduction in monolayer graphene devices on silica substrates. This nonlinearity manifests itself as a nonmonotonic dependence of the differential resistance on applied DC voltage bias across the sample. At temperatures below ~70K, the differential resistance exhibits a peak near zero bias that can be attributed to self-heating of the charge carriers. We show that the shape of this peak arises from a combination of different energy dissipation mechanisms of the carriers. The energy dissipation at higher carrier temperatures depends critically on the length of the sample. For samples longer than 10um the heat loss is shown to be determined by optical phonons at the silica-graphene interface.Comment: 4 pages, 4 figure

Generalized Log-Normal Chain-Ladder

We propose an asymptotic theory for distribution forecasting from the log normal chain-ladder model. The theory overcomes the difficulty of convoluting log normal variables and takes estimation error into account. The results differ from that of the over-dispersed Poisson model and from the chain-ladder based bootstrap. We embed the log normal chain-ladder model in a class of infinitely divisible distributions called the generalized log normal chain-ladder model. The asymptotic theory uses small $\sigma$ asymptotics where the dimension of the reserving triangle is kept fixed while the standard deviation is assumed to decrease. The resulting asymptotic forecast distributions follow t distributions. The theory is supported by simulations and an empirical application

Sources of teacher efficacy in teaching reading : success, sharing, and support

Teacher self- and collective efficacy are important motivational factors in determining teachers’ effort in their professional practice. Teachers’ higher levels of self- and collective efficacy are positively associated with student achievement in specific domains, and teachers’ enhanced wellbeing and commitment to their profession. This qualitative study explores primary teachers’ own views about naturalistic and characteristic experiences and influences that have strengthened and weakened their efficacy in teaching reading. Five themes of naturalistic sources of enhancement in self- and collective efficacy are identified that are consistent with predictions of Bandura’s social cognitive theory and studies involving interventions in schools by expert trainers. The themes are combined into a model of growth in teachers’ efficacy and can potentially inform decision-making in schools in supporting and enhancing teachers’ self- and collective efficacy when teaching reading