1,228 research outputs found
Theory of the Exciton-Phonon Coupling
The effect of electron-phonon interactions on optical absorption spectra
requires a special treatment in materials with strong electron-hole
interactions. We conceptualize these effects as exciton-phonon coupling.
Through phonon absorption and emission, the optically accessible excitons are
scattered into dark finite-momentum exciton states. We derive a practical
expression for the exciton-phonon self-energy that relates to the temperature
dependence of the optical transitions and their broadening. This expression
differs qualitatively from previous approximated expressions found in
literature
Hypertension as a Determining Factor in the Rupture of Intracranial Aneurysms, Diagnosed by 64-MDCT Angiography
Background: To determine a correlation between risk factors and the rupture of intracranial aneurysms. Methods: A cross-sectional study of 29 patients with a saccular intracranial aneurysm was obtained using consecutive sampling and examination of 64-MDCT angiography. Bivariate statistical analysis using Fisher's exact test was arranged using cross-tabulation to determine the correlation between each risk factor of age, sex, hypertension, and smoking with the occurrence of ruptured intracranial aneurysms. Results: The highest incidence of ruptured intracranial aneurysms were in patients aged <60 years (70%), male (75%), experienced hypertension (85%), and were smokers (85.7%). Only the risk factor of hypertension had a correlation with the occurrence of a ruptured intracranial aneurysm (p < 0.05). The prevalence ratio of age and sex were 1.0 and 0.9, whereas hypertension and smoking were 2.6 and 1.3. Conclusions: The risk factor of hypertension leading to a ruptured intracranial aneurysm was 2.6 times higher than non-hypertensive patients, and as such hypertension is a risk factor associated with the occurrence of ruptured intracranial aneurysm
Menuju Demokrasi Rasional: Melacak Pemikiran Jürgen Habermas Tentang Ruang Publik
As a concept widely employed to promote the deeper and more radical democracy within the framework of deliberative democracy, public sphere as formulated by Jürgen Habermas in his two books, The Structural Transformation of Public Sphere and Between Facts and Norms, acts as a crucial theory to investigate and assess the degree of publicness in todays democracy discourse. This paper aims to elaborate the concept of public sphere as written in those two books. By comparing the content of each book, this paper also classifies the similarity and differences between the concept of public sphere written in those two texts
Habits of the Home: Spatial Hegemony and the Structuration of House and Society in Brazil
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75052/1/aa.1989.91.3.02a00020.pd
Preparation of zeolite filled glassy polymer membranes
The incorporation of zeolite particles in the micrometer range into polymeric matrices was investigated as a way to improve the gas separation properties of the polymer materials used in the form of membranes. The adhesion between the polymer phase and the external surface of the particles appeared to be a major problem in the preparation of such membranes when the polymer is in the glassy state at room temperature. Various methods were investigated to improve the internal membrane structure, that is, surface modification of the zeolite external surface, preparation above the glass-transition temperature, and heat treatment. Improved structures were obtained as observed by scanning electron microscopy, but the influence on the gas separation properties was not in agreement with the observed structural improvements
Enkripsi Dan Dekripsi Dengan Algoritma Aes 256 Untuk Semua Jenis File
Kemajuan teknologi komputer dan telekomunikasi telah menjadi kebutuhan dansangat membantu dalam menyelesaikan banyak pekerjaan dengan cepat, akurat, danefisien. Namun seiring dengan kemajuan teknologi, terdapat dampak negatif berupapenyadapan data sehingga aspek keamanan dalam pertukaran informai dianggap penting.Dalam dunia informasi terdapat data-data penting dan bersifat rahasia yang tidak bolehdiketahui oleh umum.Kriptografi merupakan salah satu solusi atau metode pengamanan data yangtepat untuk menjaga kerahasiaan dan keaslian data, serta dapat meningkatkan aspekkeamanan suatu data atau informasi. Metode ini bertujuan agar informasi yang bersifatrahasia dan dikirim melalui suatu jaringan, seperti LAN atau Internet, tidak dapat diketahuiatau dimanfaatkan oleh orang atau pihak yang tidak berkepentingan. Kriptografimendukung kebutuhan dua aspek keamanan informasi, yaitu perlindungan terhadapkerahasiaan data informasi dan perlindungan terhadap pemalsuan dan pengubahaninformasi yang tidak diinginkan.Hasil penelitian menunjukkan bahwa algoritma AES dengan panjang kunci 256 bitdapat menyandikan isi suatu file sehingga dapat mengamankan file tersebut. Ukuran fileenkripsi akan bertambah 11 bytes dari file asli karena adanya proses penambahan headeryang berisi informasi ekstensi file. Dalam pengembangan sistem berikutnya diharapkansistem dapat mempunyai fasilitas untuk menyembunyikan folder yang digunakan untukmenyimpan file enkripsi maupun file dekripsi
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