Roton-Phonon Interactions in Superfluid 4He

High-resolution neutron resonance spin-echo measurements of superfluid 4He show that the roton energy does not have the same temperature dependence as the inverse lifetime. Diagrammatic analysis attributes this to the interaction of rotons with thermally excited phonons via both four- and three-particle processes, the latter being allowed by the broken gauge symmetry of the Bose condensate. The distinct temperature dependence of the roton energy at low temperatures suggests that the net roton-phonon interaction is repulsive.Comment: 5 pages, accepted versio

Kagom\'{e} ice state in the dipolar spin ice Dy_{2}Ti_{2}O_{7}

We have investigated the kagom\'{e} ice behavior of the dipolar spin-ice compound Dy_{2}Ti_{2}O_{7} in magnetic field along a [111] direction using neutron scattering and Monte Carlo simulations. The spin correlations show that the kagom\'{e} ice behavior predicted for the nearest-neighbor (NN) interacting model, where the field induces dimensional reduction and spins are frustrated in each two-dimensional kagom\'{e} lattice, occurs in the dipole interacting system. The spins freeze at low temperatures within the macroscopically degenerate ground states of the NN model.Comment: 5 pages, 3 figures, submitted to PR

Haydeeite: a spin-1/2 kagome ferromagnet

The mineral haydeeite, alpha-MgCu3(OD)6Cl2, is a S=1/2 kagome ferromagnet that displays long-range magnetic order below TC=4.2 K with a strongly reduced moment. Our inelastic neutron scattering data show clear spin-wave excitations that are well described by a Heisenberg Hamiltonian with ferromagnetic nearest-neighbor exchange J1=-38 K and antiferromagnetic exchange Jd=+11 K across the hexagons of the kagome lattice. These values place haydeeite very close to the quantum phase transition between ferromagnetic order and non-coplanar twelve-sublattice cuboc2 antiferromagnetic order. Diffuse dynamic short-range ferromagnetic correlations observed above TC persist well into the ferromagnetically ordered phase with a behavior distinct from critical scattering

KEBERHASILAN PERTUMBUHAN BIBIT SEMBUKAN PADA PENGGUNAAN BERBAGAI JUMLAH RUAS STEK BATANG DAN WAKTU PENYETEKAN

Skunk vine plant (leaf “kentutan”) is an annual herbaceous plant that grows and grows wild vines, which since ancient times known as a laxative drug fart. The study aims to determine the timing and number of segments in stem cuttings of the best growth plant seedling stem cuttings of skunk vine been implemented in practice Gardens Fak. Agriculture UPN "Veteran" Yogyakarta from August to November 2015. The research method used is the pot experiment with completely randomized design in factorial with 2 factor treatment was repeated three times. The first factor is the number of segments stem cuttings, consisting of 3 levels: S1 = the number one segment of stem cuttings, S2 = number two segments of stem cuttings, S3 = number three segments of stem cuttings. The second factor is the time cuttings, consists of three levels, namely: W1 = time of the morning (7:00 to 9:00), W2 = the time of day (11:00 to 13:00), W3 = the afternoon (15:00 to 17:00). The results showed growth plant seedling stem cuttings is best skunk vine three segment or two segments of rods and the time cuttings of afternoon. Interactions are at the age of 4 weeks the number of shoots and on the percentage of the growing shoots, namely the evening and all the number of segments, each of which is used for the segment amounted to 66.67%, 83.33% and two sections of three roads 66,67% as well as the time of day and the two sections of 62.50%

PEMOTONGAN AKAR DAN DISITRIBUSI ASIMILAT KULTIVAR KEDELAI PADA KONDISI CEKAMAN KEKERINGAN

Tanaman yang mengalami cekaman kekeringan biasanya mendistribusikan lebih banyak asimilat ke bagian akar. Penelitian ini dilakukan untuk mengetahui tanggapan kultivar kedelai terhadap pemotongan akar serta pengaruh pemotongan akar terhadap distribusi asimilat.Rancangan percobaan yang digunakan adalah rancangan acak lengkap (RAL) faktorial 3x dengan tiga ulangan. Penelitian dilaksanakan pada bulan Juli sampai Oktober 2011. Faktor pertama adalah pemotongan akar terdiri dari 3 aras (tidak dipotong, dipotong sepanjang 50% dari panjang polibag dan dipotong sepanjangT5%). Faktor kedua adalah kultivar terdiri dari aras (Anjamoro, Baluran, Grobogan). Pengamatan meliputi bobot kering tanaman, nisbah akar tajuk, bobot kering akar dan bobot kering tajuk dilakukan pada umur 56 hari setelah tanam. Pemotongan akar meningkatkan bobot kering tanaman dan bobot kering tajuk. Pemotongan akar 50Yo dari panjang polibag meningkatkan bobot kering akar kultivar Grobogan. Pemotongan akar 75oh meningkatkan nisbah akar tajuk kultivar kedelai dan menurunkan bobot kering akar kultivar Baluran

UJI KAPASITAS KERJA DAN EFISIENSI HAND TRAKTOR UNTUK PENGOLAHAN TANAH LAHAN KERING

Penelitian ini bertujuan untuk melihat kapasitas kerja dan efisiensi hand traktor pada pengolahan tanah dilahan kering dengan menggunakan bajak singkal. Bbberapa faktor yang diteliti adalah kapasitas kerja actual, kapasitas kerja teoritis dan efisiensi. Hasil penelitian menunjukkan bahwa nilai kapasitas kerja actual0,0625 haljam, nilai kapasitas kerja teoritis 0,ll4haljan dan efisiensi 56,lyo. Dengan dernikian dapat dikatakan bahwa kerja hand traktor rnasih belurn efisien

PENGARUH PENGERINGAN TENAGA SURYA DENGAN KOLEKTOR BERPENUTUP GELAS GANDA TERHADAP KUALITAS KELOPAK BUNGA ROSELA (Hibiscus sabdariffa L.)

Tanaman rosella (Hibiscus sabdarffi, L.) mempunyai kelopak bunga yang berwarna merah. Kelopak bunga tersebut banyak digunakan sebagai bahan pembuatan minuman, makanan sumber pewarna alami dan sebagai obat herbal karena mempunyai kadar protein, vitamin C, vitamin A dan antosianin yang relatif tinggi. Bunga rosella mengandung kadar air yang tinggi menyebabkan mudah terkontaminasi oleh mikroba, sehingga bunga menjadi lebih cepat busuk. Sebagai upaya untuk mempertahankan kualitas bunga telah dilakukan pengeringan dengan menggunakan pengering surya dengan kolektor berpenutup gelas ganda. Hasil pengamatan yang dilakukan pada tanggal 27-28 September 2013 menunjukkan bahwa suhu tertinggi di dalam alat pengering ini 48,1 oc dan 49.9 oc dengan kelembaban relatif pada kisaran 30-40%. Pada keadaan tersebut diperlukan waktu 2 hari untuk mengeringkan 2,3 kg kelopak bunga rosella segar dengan kadar air 90,84yo menjadi 7,47 o . Dari hasil penelitian menunjukkan bahwa kualitas bunga yang ditunjukkan dengan kadar protein, vitamin C, vitamin A dan antosianin masih dapat dipertahankan dengan kerusakan akibat pengeringan di baw ah 2o/o

Magnetic phase diagram of spatially anisotropic, frustrated spin-1/2 Heisenberg antiferromagnet on a stacked square lattice

Magnetic phase diagram of a spatially anisotropic, frustrated spin-1/2 Heisenberg antiferromagnet on a stacked square lattice is investigated using second-order spin-wave expansion. The effects of interlayer coupling and the spatial anisotropy on the magnetic ordering of two ordered ground states are explicitly studied. It is shown that with increase in next nearest neighbor frustration the second-order corrections play a significant role in stabilizing the magnetization. We obtain two ordered magnetic phases (Neel and stripe) separated by a paramagnetic disordered phase. Within second-order spin-wave expansion we find that the width of the disordered phase diminishes with increase in the interlayer coupling or with decrease in spatial anisotropy but it does not disappear. Our obtained phase diagram differs significantly from the phase diagram obtained using linear spin-wave theory.Comment: 22 pages, 6 figures, minor changes from previous versio