Pengembangan Media Presentasi Interaktif Semi Laboratorium Virtual Pada Pokok Bahasan Listrik Dinamis

Penelitian ini adalah penelitian pengembangan yang secara umum bertujuan untuk: (1) Mengembangkan bahan ajar Fisika/bahan bacaan siswa pada pokok bahasan listrik dinamis untuk SMA kelas X semester 2 dan (2) Mengembangkan produk perangkat pembelajaran Fisika berbasis komputer berupa media presentasi interaktif semi laboratorium virtual untuk pembelajaran di kelas. Model pengembangan media yang digunakan adalah model R2D2, terdiri dari tiga tahap yaitu: (1) penetapan (define), (2) perancangan (design), pengembangan (develop) dan (3) diseminasi terbatas (disseminate). Penelitian ini dilaksanakan dijurusan Fisika, FMIPA Universitas Negeri Makassar mahasiswa S1. Analisis data yang digunakan dalam penelitian ini adalah analisis statistik deskriptif. Statistik deskriptif digunakan untuk menganalisis kesahihan media presentasi interaktif Semi Laboratorium Virtual pada pokok bahasan listrik dinamis. Media presentasi interaktif divalidasi oleh seorang pakar media pembelajaran dan dilakukan penilaian oleh praktisi yakni mahasiswa program pascasarjana (S2) yang berprofesi sebagai guru sebanyak 13 orang dan uji coba terbatas dilakukan pada mahasiswa jurusan fisika (S1) sebanyak 6 orang. Hasil penelitian menunjukkan bahwa media presentasi interaktif Semi Laboratorium Virtual meliputi penilaian validator (ahli dan praktisi) memberikan penilaian rata-rata 89,2 % untuk kulitas perangkat lunak dan 87,5 % untuk daya tarik, dan penilaian Untuk hasil penilaian oleh praktisi diperoleh rata-rata persentase untuk kepraktisan dan sistematika media presentasi interaktif adalah 88 % atau tergolong dalam kategori baik. Pada saat uji coba terbatas juga secara rata-rata diperoleh penilaian 82 % semua berada pada kategori baik. Hasil penilaian tersebut lebih tinggi dari standar penerimaan yang telah ditentukan yaitu 75,0 %, hal ini menunjukkan bahwa perangkat lunak presentasi yang merupakan media pembelajaran yang diperuntukkan untuk Guru sebagai media presentasi interaktif Semi Laboratorium Virtual dalam melakukan pembelajaran di kelas, memenuhi kesahihan atau valid untuk digunakan sebagai media dalam pelaksanaan pembelajaran

Strain balanced quantum posts

Quantum posts are assembled by epitaxial growth of closely spaced quantum dot layers, modulating the composition of a semiconductor alloy, typically InGaAs. In contrast with most self-assembled nanostructures, the height of quantum posts can be controlled with nanometer precision, up to a maximum value limited by the accumulated stress due to the lattice mismatch. Here we present a strain compensation technique based on the controlled incorporation of phosphorous, which substantially increases the maximum attainable quantum post height. The luminescence from the resulting nanostructures presents giant linear polarization anisotropy.Comment: Submitted to Applied Physics Letters (7th March 2011). 4 pages, 4 figure

Quantum dynamics and breakdown of classical realism in nonlinear oscillators

The dynamics of a quantum nonlinear oscillator is studied in terms of its quasi-flow, a dynamical mapping of the classical phase plane that represents the time-evolution of the quantum observables. Explicit expressions are derived for the deformation of the classical flow by the quantum nonlinearity in the semiclassical limit. The breakdown of the classical trajectories under the quantum nonlinear dynamics is quantified by the mismatch of the quasi-flow carried by different observables. It is shown that the failure of classical realism can give rise to a dynamical violation of Bell's inequalities.Comment: RevTeX 4 pages, no figure

Summer drought reconstruction in Northeastern Spain inferred from a tree-ring latewood network since 1734

Drought recurrence in the Mediterranean is regarded as a fundamental factor for socioeconomic development and the resilience of natural systems in context of global change. However, knowledge of past droughts has been hampered by the absence of high-resolution proxies. We present a drought reconstruction for the northeast of the Iberian Peninsula based on a new dendrochronology network considering the Standardized Evapotranspiration Precipitation Index (SPEI). A total of 774 latewood width series from 387 trees of P. sylvestris and P. uncinata was combined in an interregional chronology. The new chronology, calibrated against gridded climate data, reveals a robust relationship with the SPEI representing drought conditions of July and August. We developed a summer drought reconstruction for the period 1734– 2013 representative for the northeastern and central Iberian Peninsula. We identified 16 extremely dry and 17 extremely wet summers and four decadal scale dry and wet periods, including 2003–2013 as the driest episode of the reconstruction

Temperature variability in the Iberian Range since 1602 inferred from tree-ring records

Tree rings are an important proxy to understand the natural drivers of climate variability in the Mediterranean Basin and hence to improve future climate scenarios in a vulnerable region. Here, we compile 316 tree-ring width series from 11 conifer sites in the western Iberian Range. We apply a new standardization method based on the trunk basal area instead of the tree cambial age to develop a regional chronology which preserves high- to low-frequency variability. A new reconstruction for the 1602-2012 period correlates at g''0.78 with observational September temperatures with a cumulative mean of the 21 previous months over the 1945-2012 calibration period. The new IR2Tmax reconstruction is spatially representative for the Iberian Peninsula and captures the full range of past Iberian Range temperature variability. Reconstructed long-term temperature variations match reasonably well with solar irradiance changes since warm and cold phases correspond with high and low solar activity, respectively. In addition, some annual temperature downturns coincide with volcanic eruptions with a 3-year lag

Tree-ring-based drought reconstruction in the Iberian Range (east of Spain) since 1694

Droughts are a recurrent phenomenon in the Mediterranean basin with negative consequences for society, economic activities, and natural systems. Nevertheless, the study of drought recurrence and severity in Spain has been limited so far due to the relatively short instrumental period. In this work, we present a reconstruction of the standardized precipitation index (SPI) for the Iberian Range. Growth variations and climatic signals within the network are assessed developing a correlation matrix and the data combined to a single chronology integrating 336 samples from 169 trees of five different pine species distributed throughout the province of Teruel. The new chronology, calibrated against regional instrumental climatic data, shows a high and stable correlation with the July SPI integrating moisture conditions over 12 months forming the basis for a 318-year drought reconstruction. The climate signal contained in this reconstruction is highly significant (p < 0.05) and spatially robust over the interior areas of Spain located above 1000 meters above sea level (masl). According to our SPI reconstruction, seven substantially dry and five wet periods are identified since the late seventeenth century considering =±1.76 standard deviations. Besides these, 36 drought and 28 pluvial years were identified. Some of these years, such as 1725, 1741, 1803, and 1879, are also revealed in other drought reconstructions in Romania and Turkey, suggesting that coherent larger-scale synoptic patterns drove these extreme deviations. Since regional drought deviations are also retained in historical documents, the tree-ring-based reconstruction presented here will allow us to cross-validate drought frequency and magnitude in a highly vulnerable region

Temperature variability of the Iberian Range since 1602 inferred from tree-ring records

Tree rings are an important proxy to understand the natural drivers of climate variability in the Mediterranean Basin and hence to improve future climate scenarios in a vulnerable region. Here, we compile 316 treering width series from 11 conifer sites in the western Iberian Range. We apply a new standardization method based on the trunk basal area instead of the tree cambial age to develop a regional chronology which preserves high to low-frequency variability. A new reconstruction for the 1602–2012 period correlates at ??0.78 with observational September temperatures with a cumulative mean of the 21 previous months over the 1945– 2012 calibration period. The new IR2Tmax reconstruction is spatially representative for the Iberian Peninsula and captures the full range of past Iberian Range temperature variability. Reconstructed longterm temperature variations match reasonably well with solar irradiance changes since warm and cold phases correspond with high and low solar activity, respectively. In addition, some annual temperature downturns coincide with volcanic eruptions with a 3-year lag

Proceso automático para la medida de las reflectancias. 1.- Descripción preliminar

To calculated the physical constant, n, k, from the reflectance measurements in two different media of known refractive indices, it is necessary to apply a stadistic criterion that represents to obtein a great numher of experimental data. The preliniinary description of the method used shows how et is simplified the calculation of the values of n, k, from the experimental data of reflectance