Recurrent Variational Approach to the Two-Leg Hubbard Ladder

We applied the Recurrent Variational Approach to the two-leg Hubbard ladder. At half-filling, our variational Ansatz was a generalization of the resonating valence bond state. At finite doping, hole pairs were allowed to move in the resonating valence bond background. The results obtained by the Recurrent Variational Approach were compared with results from Density Matrix Renormalization Group.Comment: 10 pages, 14 Postscript figure

MEMS Gradiometers for Attitude Determination on CubeSats

This paper presents the design, fabrication and testing of a new high sensitivity gravity sensor for attitude determination in CubeSats. The project is a collaboration between the Institute for Gravitational Research at the University of Glasgow and ÅAC-Clyde. The gravitational gradiometer takes advantages of the technology of microelectromechanical systems (MEMS) and determines the attitude of the satellite by a differential gravity measurement, the principle at the base of gravitational gradiometry. The capacitive readout allows to measure the rotation of the MEMS gradiometer and consequently evaluate the angle changes of the CubeSat. The developed geometry consists of two symmetrical masses connected to a fixed support by four thin flexure hinges. The all-Silicon sensor resonates at a frequency of 6 Hz, and has a total mass of less than 2 g. It is expected that the sensor geometry and the readout demonstrated would be suitable to achieve the performances required from CubeSat systems and detect a rotation of the small satellite of 1 degree, in order to offer performance comparable to other state-of-the-art sensors currently available on the market

Effects of a recombinant gene expression on ColE1-like plasmid segregation in Escherichia coli

<p>Abstract</p> <p>Background</p> <p>Segregation of expression plasmids leads to loss of recombinant DNA from transformed bacterial cells due to the irregular distribution of plasmids between the daughter cells during cell division. Under non-selective conditions this segregational instability results in a heterogeneous population of cells, where the non-productive plasmid-free cells overgrow the plasmid-bearing cells thus decreasing the yield of recombinant protein. Amongst the factors affecting segregational plasmid instability are: the plasmid design, plasmid copy-number, host cell genotype, fermentation conditions etc. This study aims to investigate the influence of transcription and translation on the segregation of recombinant plasmids designed for constitutive gene expression in <it>Escherichia coli </it>LE392 at glucose-limited continuous cultivation. To this end a series of pBR322-based plasmids carrying a synthetic human interferon-gamma (hIFNγ) gene placed under the control of different regulatory elements (promoter and ribosome-binding sites) were used as a model.</p> <p>Results</p> <p>Bacterial growth and product formation kinetics of transformed <it>E. coli </it>LE392 cells cultivated continuously were described by a structured kinetic model proposed by Lee et al. (1985). The obtained results demonstrated that both transcription and translation efficiency strongly affected plasmid segregation. The segregation of plasmid having a deleted promoter did not exceed 5% after 190 h of cultivation. The observed high plasmid stability was not related with an increase in the plasmid copy-number. A reverse correlation between the yield of recombinant protein (as modulated by using different ribosome binding sites) and segregational plasmid stability (determined by the above model) was also observed.</p> <p>Conclusions</p> <p>Switching-off transcription of the hIFNγ gene has a stabilising effect on ColE1-like plasmids against segregation, which is not associated with an increase in the plasmid copy-number. The increased constitutive gene expression has a negative effect on segregational plasmid stability. A kinetic model proposed by Lee et al. (1985) was appropriate for description of <it>E. coli </it>cell growth and recombinant product formation in chemostat cultivations.</p

Pengaruh Persepsi Masyarakat Kecamatan Rantau Utara terhadap Minat Memilih Calon Kepala Daerah Independen pada Pilkada Kabupaten Labuhanbatu Tahun 2015

&nbsp; The Regional Head Election of Labuhanbatu Regency is one of the forums for political participation for the public. The results of the independent candidate's vote in the Labuhanbatu Regency Election 2015 were able to compete with political party candidate. This phenomenon shows the public interest in choosing independent candidates. This research aims to determine how the effect of public perception on interest in choosing independent regional head candidate. Research method uses hypothesis test between X variable (perception) and Y variable (interest) and looks for the relationship between it. Population in research were voters in Rantau Utara District. Research used questionnaire distributed to 100 respondents who were selected through a sampling technique. Data analysis technique using cross tabulation, Pearson correlation and hypothesis test. &nbsp; Keyword : Independent Candidate, Perception, Interest, Political Participatio