Large Spin Formation and Thermodynamic Properties of Disordered Spin Ladders with Site Dilution

Low temperature properties of antiferromagnetic two-leg spin-1/2 ladders with bond randomness and site dilution (or doping with nonmagnetic impurities) are studied using the real-space renormalization-group technique. We find that for non zero doping concentrations the systems are driven into a phase dominated by large effective spins, i.e. the Large Spin phase. The susceptibility follows a universal Curie-like 1/T behavior at low temperature,regardless of the doping concentrations (as long as it is nonzero) and the strength of bond randomness. Very similar behavior has been found in ladders that are doped with magnetic impurities that carry spin-1.Comment: 9 pages, 4 figure

Spin Waves in Antiferromagnetic Spin Chains with Long Range Interactions

We study antiferromagnetic spin chains with unfrustrated long-range interactions that decays as a power law with exponent $\beta$, using the spin wave approximation. We find for sufficiently large spin $S$, the Neel order is stable at T=0 for $\beta < 3$, and survive up to a finite Neel temperature for $\beta < 2$, validating the spin-wave approach in these regimes. We estimate the critical values of $S$ and $T$ for the Neel order to be stable. The spin wave spectra are found to be gapless but have non-linear momentum dependence at long wave length, which is responsible for the suppression of quantum and thermal fluctuations and stabilizing the Neel state. We also show that for $\beta\le 1$ and for a large but finite-size system size $L$, the excitation gap of the system approaches zero slower than $L^{-1}$, a behavior that is in contrast to the Lieb-Schulz-Mattis theorem

Dynamics of weakly coupled random antiferromagnetic quantum spin chains

We study the low-energy collective excitations and dynamical response functions of weakly coupled random antiferromagnetic spin-1/2 chains. The interchain coupling leads to Neel order at low temperatures. We use the real-space renormalization group technique to tackle the intrachain couplings and treat the interchain couplings within the Random Phase Approximation (RPA). We show that the system supports collective spin wave excitations, and calculate the spin wave velocity and spectra weight within RPA. Comparisons will be made with inelastic neutron scattering experiments quasi-one-dimensional disordered spin systems such as doped CuGeO$_3$Comment: 4 page

Analysis of Market-Based Approach on the Customer Value and Customer Satisfaction and Its Implication on Customer Loyalty of Organic Products in Indonesia

AbstractObjectives research to obtain empirical evidence and find phenomenon clarity about variable market-based to customer's value and also customer's satisfaction which influencing customer loyalities, and digging the product marketing problems organic products in Indonesia. Methods of data analysis used to test the hypothesis is path analysis. The proper methods to carry out descriptive and verification method through field data collection are descriptive survey and explanatory survey. The result of the review obtained from the research objectives above are expected to make an approach which is applicable in solving the problems faced by companies, especially the organic products companies, and other similar companies in general, especially those dealing with the market-based customer's value and satisfaction, also the customer's loyalty

STRATEGI PENINGKATAN EFISIENSI PRODUKSI DAN DISTRIBUSI KOPI ARABIKA DI KABUPATEN GARUT

Areal pertanaman kopi arabika di Kabupaten Garut Jawa Barat sangat terbatas dan produksinya masih relatif rendah, sementara permintaan terus meningkat dari tahun ke tahun, hal ini dikarenakan kopi arabika Garut memiliki rasa yang nikmat serta aroma yang khas. Peningkatan permintaan mendorong para produsen dan distributor untuk terus meningkatkan efisiensi produksi dan distribusi sehingga dapat memenuhi kebutuhan pasar yang semakin besar. Tujuan penelitian ini untuk menganalisis strategi peningkatan efisiensi produksi dan distribusi melalui peningkatan produktivitas, kualitas dan dayasaing serta mengurangi biaya produksi sehingga tercapai keberlanjutannya baik aspek ekonomi, sosial maupun aspek lingkungan serta efisiensi rantai pasok disepanjang jalur distribusinya. Untuk menganalisis dan menemukan strategi yang sesuai dalam mengidentifikasi dan mencari hubungan antar variabel yang berbeda serta melihat dampaknya terhadap variabel lainnya, maka dilakukan simulasi dinamik dengan Vensim yang dinyatakan dalam diagram kausatik. Hasil penelitian menunjukkan bahwa efiensiesi ditingkat produksi sangat dipengaruhi oleh sistem kelembagaan ditingkat produsen dan pengembangan sumberdaya manusia baik budidaya, panen, pasca panen, manajemen dan pemasaran. Hal tersebut menjadi titik kunci dalam peningkatan efisiensi produksi dan distribusi. Oleh karena itu, diperlukan model kelembagaan yang dapat berperan sebagai distributor dan dapat mengakses sistem pembiayaan serta permodalan sekaligus berperan sebagai off-taker. Koperasi, dapat menjadi model kelembagaan yang sesuai serta dapat dikembangkan menjadi Korporasi Petani sesuai dengan Permentan No. 18 Tahun 2018

Nyamankah ruangan di Universitas XYZ?

Tulisan ini mengkaji kualitas parameter akustik, dari lima ruangan di Univeristas XYZ, yang terbagi ke dalam tiga klaster fungsi (studio, ruang rapat, dan kelas). Rekaman suara dari sumber suara impulsif dianalisis dengan menggunakan perangkat lunak REW untuk menghasilkan reverberation time RT60 dan speech clarity C50 yang dapat digunakan untuk memeringkat kelima ruangan tersebut. Analisis menunjukkan adanya korelasi yang erat antara volume ruangan, material penyusun ruangan, dan isi ruangan terhadap kualitas akustik ruangan

Spin Fluctuations and the Pseudogap in Organic Superconductors

We show that there are strong similarities in the spin lattice relaxation of non-magnetic organic charge transfer salts, and that these similarities can be understood in terms of spin fluctuations. Further, we show that, in all of the kappa-phase organic superconductors for which there is nuclear magnetic resonance data, the energy scale for the spin fluctuations coincides with the energy scale for the pseudogap. This suggests that the pseudogap is caused by short-range spin correlations. In the weakly frustrated metals k-(BEDT-TTF)_2Cu[N(CN)_2]Br, k-(BEDT-TTF)_2Cu(NCS)_2, and k-(BEDT-TTF)_2Cu[N(CN)_2]Cl (under pressure) the pseudogap opens at the same temperature as coherence emerges in the (intralayer) transport. We argue that this is because the spin correlations are cut off by the loss of intralayer coherence at high temperatures. We discuss what might happen to these two energy scales at high pressures, where the electronic correlations are weaker. In these weakly frustrated materials the data is well described by the chemical pressure hypothesis (that anion substitution is equivalent to hydrostatic pressure). However, we find important differences in the metallic state of k-(BEDT-TTF)_2Cu_2(CN)_3, which is highly frustrated and displays a spin liquid insulating phase. We also show that the characteristic temperature scale of the spin fluctuations in (TMTSF)_2ClO_4 is the same as superconducting critical temperature, which may be evidence that spin fluctuations mediate the superconductivity in the Bechgaard salts.Comment: 7 pages, 4 figures; to appear in PR

Pembelajaran Berbasis Teknologi Untuk Generasi Z

Makalah ini membahas sebuah strategi pembelajaran berbasis teknologi yang diperlukan untuk menghadapi generasi Z. Tablet berbasis android dengan perangkat lunak Speedy Spectrum Analyzer digunakan untuk menjelaskan materi gelombang stasioner pada mata pelajaran Fisika kelas XII. Titik berat dari penerapan teknologi ini dalam pembelajaran adalah 1) kemudahan untuk mendapatkan perangkat yang digunakan dan 2) keakuratan hasil yang diperoleh dari perangkat ini. Penggunaan teknologi ini diharapkan mempertajam konsep dan sekaligus mengikis miskonsepsi siswa dalam materi gelombang stasioner.Kata Kunci : generasi Z, gelombang stasioner, fisika, teknologi, tablet, androi

Stakeholder Collaboration in Developing Sustainable Ecotourism in Badung

The main challenge in developing sustainable ecotourism in Indonesia is to maintain a balance of economic, socio-cultural, and environmental development. The emergence of problems in tourism development is due to the direction of policies that prioritize the economic aspect so that it has an impact on the destruction of environmental ecosystems and the erosion of local wisdom and culture. This study aims to assess stakeholder collaboration in developing sustainable ecotourism in Badung Regency, Bali Province. The research approach used is a qualitative and exploratory research design where the data are sourced from in-depth interviews, FGDs, and secondary data. The research paradigm adheres to a constructivist view, data analysis is inductive. The findings of this study indicate that there are initiatives from the government to support the private sector, the community, and environmental conservation although it is not yet optimal. The varied types of relationships among stakeholders still leave a lack of understanding in building mutual trust and interdependence. For this reason, it is necessary for the commitment of stakeholders, especially the government in the form of providing financial, coaching, and administrative support so that cooperation continues to be strengthened so that it can gradually improve collaboration and reduce community dependence on the government and encourage business independence without neglecting socio-cultural interests and environmental preservation. Further studies are needed to understand strategies that can drive appropriate initiatives that impact stakeholder understanding, mutual trust, and self-reliance of the private sector and local communities to develop sustainable ecotourism. Keywords: collaboration, stakeholder, sustainable ecotouris

Tinjauan Kekuatan Beton pada Usia Muda dengan Penambahan Polypropylene Fibre

Dewasa ini pemakaian beton sangat berkembang pesat pada kegiatan kontruksi, dikarenakan beton memiliki kelebihan mudah dibentuk sesuai keinginan, memiliki kuat tekan yang baik dan lain – lain. Tetapi beton memiliki kelemahan pada sifat yang getas dan kuat tarik yang rendah, sehingga kontruksi beton diberi tulangan untuk mengatasi pada bagian tarik. Maka diperlukan beton khusus untuk meningkatkan kuat tarik maupun kuat lentur yaitu beton serat. Beton serat adalah beton dengan bahan tambah serat. Dalam penelitian ini campuran beton menggunakan bahan tambah polypropylene fibre, sehingga diharapkan dapat meningkatkan kualitas beton pada umumnya dan khususnya pada kuat tarik belah dan kuat lentur. Polypropylene fibre menggunakan produk dari Sika dengan diameter 18 mikron dan panjang 12 mm. Pengujian ini meliputi pada kuat tekan, kuat tarik belah dan kuat lentur. Untuk pengujian kuat tekan dan kuat tarik belah menggunakan benda uji silinder dengan diameter 15 cm dan tinggi 30 cm, sedangkan kuat lentur menggunakan benda uji balok dengan panjang 60 cm, lebar 15 cm dan tinggi 15 cm. Benda uji terdiri dari tiga buah silinder dan tiga buah balok untuk masing - masing pengujian. Dari pengujian slump dapat disimpulkan tidak ada Perubahan berarti dalam penggunanan polypropylene fibre. Dan dari pengujian kuat tekan, kuat tarik belah dan kuat lentur di dapatkan nilai optimum pada beton normal ditambah polypropylene fibre. Pada kuat tekan terjadi peningkatan sebesar 4,44 % dibandingkan beton normal (N), sedangkan pada kuat tarik belah terjadi peningkatan sebesar 16,96% dibandingkan beton normal (N), dan pada kuat lentur terjadi peningkatan sebesar 16,47 % dibandingkan beton normal (N)