The transient performance of a hydraulic turbine driven inducer - Computer predictions and test verification Final report

Analog and digital computer programs for predicting transient performance of inducer driven by hydraulic turbin

Germanium Detector with Internal Amplification for Investigation of Rare Processes

Device of new type is suggested - germanium detector with internal amplification. Such detector having effective threshold about 10 eV opens up fresh opportunity for investigation of dark matter, measurement of neutrino magnetic moment, of neutrino coherent scattering at nuclei and for study of solar neutrino problem. Construction of germanium detector with internal amplification and perspectives of its use are described.Comment: 13 pages, latex, 3 figures, report at NANP-99, International Conference on Non-Accelerator Physics, Dubna, Russia, June 29- July 3, 1999. To be published in the Proceeding

Performance of AAOmega: the AAT multi-purpose fibre-fed spectrograph

AAOmega is the new spectrograph for the 2dF fibre-positioning system on the Anglo-Australian Telescope. It is a bench-mounted, double-beamed design, using volume phase holographic (VPH) gratings and articulating cameras. It is fed by 392 fibres from either of the two 2dF field plates, or by the 512 fibre SPIRAL integral field unit (IFU) at Cassegrain focus. Wavelength coverage is 370 to 950nm and spectral resolution 1,000-8,000 in multi-Object mode, or 1,500-10,000 in IFU mode. Multi-object mode was commissioned in January 2006 and the IFU system will be commissioned in June 2006. The spectrograph is located off the telescope in a thermally isolated room and the 2dF fibres have been replaced by new 38m broadband fibres. Despite the increased fibre length, we have achieved a large increase in throughput by use of VPH gratings, more efficient coatings and new detectors - amounting to a factor of at least 2 in the red. The number of spectral resolution elements and the maximum resolution are both more than doubled, and the stability is an order of magnitude better. The spectrograph comprises: an f/3.15 Schmidt collimator, incorporating a dichroic beam-splitter; interchangeable VPH gratings; and articulating red and blue f/1.3 Schmidt cameras. Pupil size is 190mm, determined by the competing demands of cost, obstruction losses, and maximum resolution. A full suite of VPH gratings has been provided to cover resolutions 1,000 to 7,500, and up to 10,000 at particular wavelengths.Comment: 13 pages, 4 figures; presented at SPIE, Astronomical Telescopes and Instrumentation, 24 - 31 May 2006, Orlando, Florida US

Eigenvector statistics in non-Hermitian random matrix ensembles

We study statistical properties of the eigenvectors of non-Hermitian random matrices, concentrating on Ginibre's complex Gaussian ensemble, in which the real and imaginary parts of each element of an N x N matrix, J, are independent random variables. Calculating ensemble averages based on the quantity $< L_\alpha | L_\beta >$, where $< L_\alpha |$ and $| R_\beta >$ are left and right eigenvectors of J, we show for large N that eigenvectors associated with a pair of eigenvalues are highly correlated if the two eigenvalues lie close in the complex plane. We examine consequences of these correlations that are likely to be important in physical applications.Comment: 4 pages, no figure

Model for nucleation in GaAs homoepitaxy derived from first principles

The initial steps of MBE growth of GaAs on beta 2-reconstructed GaAs(001) are investigated by performing total energy and electronic structure calculations using density functional theory and a repeated slab model of the surface. We study the interaction and clustering of adsorbed Ga atoms and the adsorption of As_2 molecules onto Ga atom clusters adsorbed on the surface. The stable nuclei consist of bound pairs of Ga adatoms, which originate either from dimerization or from an indirect interaction mediated through the substrate reconstruction. As_2 adsorption is found to be strongly exothermic on sites with a square array of four Ga dangling bonds. Comparing two scenarios where the first As_2 gets incorporated in the incomplete surface layer, or alternatively in a new added layer, we find the first scenario to be preferable. In summary, the calculations suggest that nucleation of a new atomic layer is most likely on top of those surface regions where a partial filling of trenches in the surface has occurred before.Comment: 8 pages, 14 figures, Submitted to Phys. Rev. B (December 15, 1998). Other related publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm

PENEMPELAN KERANG Septifer bilocularis PADA SUBSTRAT DALAM AGREGASI KERANG DI DAERAH PASANG SURUT PESISIR TIWOHO

&nbsp; Research of mussel attachment, Septiver billocularis was carried out on the intertidal zone of coastal Tiwoho, north Sulawesi. The objectives of this study were 1) to identify type of substrates (organic and inorganic) to be attached by box mussel Septifer bilocularis, 2) to identify substrate preferences of Septifer bilocularis settlement. 3) to know the favorite position of settlement in mussel aggregation. The PVC plate has 16 holes, each with diameter of 1.8 cm, which had been filled randomly with organic substrate of coconut fibers and palm fibers, and mussel shell with byssus threads, then inorganic with plastic rope. Each substrate had 4 replicates. The PVC plate, four replications, each was placed at edge and middle of large aggregation, the PVC plate with substrates was also placed in isolated aggregation. All PVC plates were placed in intertidal Tiwoho for 1.5 months. The settlement data were analyzed using a Two-Way ANOVA with substrata and position in patch as the main factor. Before running the test, data were transformed using arcsin. The results showed that the settlement of box mussel (&lt; 1 mm) attached to organic substrata such as coconut and palm fibers, as well as inorganic substrates, plastic rope. Settlement of box mussels on shells with byssus threads had sizes ranging from &gt; 1 mm to - &lt; 3 mm. A Two-way ANOVA test shows that settlement was not affected by substrata (P &gt; 0.05), the settlement of box mussel was affected by position in aggregation (P &lt; 0.05). Factors such as the effect of physical, chemical, and biological on box mussel settlement are discussed. Keywords: Aggregation, Attachment, Shellfish, Substrate, Tiwoho Coast ABSTRAK `&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Penelitian penempelan kerang Septiver bilocularis pada substrat telah dilakukan di zona intertidal di pesisir Tiwoho, Sulawesi Utara. Tujuan dari penelitian ini adalah 1) untuk mengidentifikasi jenis-jenis substrat organik dan non organik yang menjadi substrat penempelan kerang Septifer bilocularis, 2) untuk mengidentifikasi substrat preferensi (favorit) pada penempelan kerang Septifer bilocularis. 3) untuk mengetahui posisi favorit penempelan dalam agregasi kerang. Plat PVC memiliki 16 lubang dengan diameter masing-masing 1,8 cm yang telah diisi secara acak dengan substrat organik serabut kelapa, serabut pohon seho, dan cangkan dengan byssus, serta substrat inorganik tali plastic. Setiap substrat memiliki 4 ulangan. Plat PVC dengan substrat ditempatkan di posisi pinggir dan tengah agregasi besar, serta agregasi kecil. Penempatan plat PVC dilakukan secara terpisah (4 kali ulangan) baik di posisi pinggir dan tengah untuk agregasi besar, serta 4 ulangan secara terpisah untuk masing- masing agregasi kecil. Semua plat PVC ditempatkan di intertidal Tiwoho selama 1,5 bulan. Data penempelan kerang dianalisa dengan menggunakan 2 Arah-ANOVA dengan substrat dan posisi dalam agregasi sebagai faktor utama. Sebelum menjalankan pengujian, data ditransformasikan menggunakan arcsinh. Hasil penelitian menunjukkan bahwa penempelan larva kerang yang menempel pada substrat organik, yaitu serabut kelapa dan seho, serta inorganic tali plastic memiliki ukuran &lt; 1 mm, serta substrat organik cangkang induk dengan byssus, yang memiliki ukuran antara &gt; 1 mm sampai - &lt; 3 mm. Uji ANOVA dua arah menunjukkan bahwa penempelan tidak dipengaruhi oleh substrat (P &gt; 0,05), penempelan kerang dipengaruhi oleh posisi dalam agregasi (P &lt; 0,05). Faktor-faktor seperti fisik, kimia, dan biologis yang mempengaruhi penempelan kerang kotak dibahas dalam diskusi. Kata kunci: Agregasi, Penempelan, Kerang, Substrat, Pesisir Tiwoh

Intercomparison of snow depth retrievals over Arctic sea ice from radar data acquired by Operation IceBridge

Since 2009, the ultra-wideband snow radar on Operation IceBridge (OIB; a NASA airborne mission to survey the polar ice covers) has acquired data in annual campaigns conducted during the Arctic and Antarctic springs. Progressive improvements in radar hardware and data processing methodologies have led to improved data quality for subsequent retrieval of snow depth. Existing retrieval algorithms differ in the way the air–snow (a–s) and snow–ice (s–i) interfaces are detected and localized in the radar returns and in how the system limitations are addressed (e.g., noise, resolution). In 2014, the Snow Thickness On Sea Ice Working Group (STOSIWG) was formed and tasked with investigating how radar data quality affects snow depth retrievals and how retrievals from the various algorithms differ. The goal is to understand the limitations of the estimates and to produce a well-documented, long-term record that can be used for understanding broader changes in the Arctic climate system. Here, we assess five retrieval algorithms by comparisons with field measurements from two ground-based campaigns, including the BRomine, Ozone, and Mercury EXperiment (BROMEX) at Barrow, Alaska; a field program by Environment and Climate Change Canada at Eureka, Nunavut; and available climatology and snowfall from ERA-Interim reanalysis. The aim is to examine available algorithms and to use the assessment results to inform the development of future approaches. We present results from these assessments and highlight key considerations for the production of a long-term, calibrated geophysical record of springtime snow thickness over Arctic sea ice

Differences in genotype and virulence among four multidrug-resistant <i>Streptococcus pneumoniae</i> isolates belonging to the PMEN1 clone

We report on the comparative genomics and characterization of the virulence phenotypes of four &lt;i&gt;S. pneumoniae&lt;/i&gt; strains that belong to the multidrug resistant clone PMEN1 (Spain&lt;sup&gt;23F&lt;/sup&gt; ST81). Strains SV35-T23 and SV36-T3 were recovered in 1996 from the nasopharynx of patients at an AIDS hospice in New York. Strain SV36-T3 expressed capsule type 3 which is unusual for this clone and represents the product of an in vivo capsular switch event. A third PMEN1 isolate - PN4595-T23 - was recovered in 1996 from the nasopharynx of a child attending day care in Portugal, and a fourth strain - ATCC700669 - was originally isolated from a patient with pneumococcal disease in Spain in 1984. We compared the genomes among four PMEN1 strains and 47 previously sequenced pneumococcal isolates for gene possession differences and allelic variations within core genes. In contrast to the 47 strains - representing a variety of clonal types - the four PMEN1 strains grouped closely together, demonstrating high genomic conservation within this lineage relative to the rest of the species. In the four PMEN1 strains allelic and gene possession differences were clustered into 18 genomic regions including the capsule, the blp bacteriocins, erythromycin resistance, the MM1-2008 prophage and multiple cell wall anchored proteins. In spite of their genomic similarity, the high resolution chinchilla model was able to detect variations in virulence properties of the PMEN1 strains highlighting how small genic or allelic variation can lead to significant changes in pathogenicity and making this set of strains ideal for the identification of novel virulence determinant