4,238 research outputs found
Pharmaceutical Formulation for Poorly Water Soluble Camptothecin Analogues
The present invention provides a general method to retard the precipitation inception time for poorly water-soluble camptothecin analogues from a supersaturated solution by a chemical conversion approach via pH alteration. This method is successfully utilized to prepare stable parenteral formulations for silatecan 7-t-butyldimethylsilyl-10-hydroxycamptothecin (DB-67), a poorly water-soluble lipophilic camptothecin analogue, in aqueous solutions containing β-cyclodextrin sulfobutyl ether (SBE-CD) or other solubilizing agents. The formulations manufactured by this method are more simple and cost-effective, of higher doses and better quality in terms of manufacture loss and formulation stability, and can be free of organic solvents (e.g., DMSO or N-methyl-2-pyrrolidinone)
Liposomal, Ring-Opened Camptothecins with Prolonged, Site-Specific Delivery of Active Drug to Solid Tumors
A method for preparing a stable dispersion of a camptothecin, camptothecin prodrug, or analog thereof for administration to a patient in need thereof includes preparing a solution of the camptothecin, wherein the solution has a pH which places substantially an entirety of that camptothecin in a carboxylate form. The camptothecin may be a neutral camptothecin. The solution is next loaded into a liposome including at least one lipid, which may be a phospholipid. An intraliposomal pH is maintained which preserves substantially an entirety of the camptothecin in the carboxylate form. The liposomal dispersion is administered to an individual in need thereof, whereby the liposomes accumulate at and permeate into tumor tissue and an active, lactone form camptothecin is released in situ at the tumor site. Compositions formulated in accordance with the described method for treatment of a cancer in an animal in need thereof are provided also
Do unbalanced data have a negative effect on LDA?
For two-class discrimination, Xie and Qiu [The effect of imbalanced data sets on LDA: a theoretical and empirical analysis, Pattern Recognition 40 (2) (2007) 557–562] claimed that, when covariance matrices of the two classes were unequal, a (class) unbalanced data set had a negative effect on the performance of linear discriminant analysis (LDA). Through re-balancing 10 real-world data sets, Xie and Qiu [The effect of imbalanced data sets on LDA: a theoretical and empirical analysis, Pattern Recognition 40 (2) (2007) 557–562] provided empirical evidence to support the claim using AUC (Area Under the receiver operating characteristic Curve) as the performance metric. We suggest that such a claim is vague if not misleading, there is no solid theoretical analysis presented in Xie and Qiu [The effect of imbalanced data sets on LDA: a theoretical and empirical analysis, Pattern Recognition 40 (2) (2007) 557–562], and AUC can lead to a quite different conclusion from that led to by misclassification error rate (ER) on the discrimination performance of LDA for unbalanced data sets. Our empirical and simulation studies suggest that, for LDA, the increase of the median of AUC (and thus the improvement of performance of LDA) from re-balancing is relatively small, while, in contrast, the increase of the median of ER (and thus the decline in performance of LDA) from re-balancing is relatively large. Therefore, from our study, there is no reliable empirical evidence to support the claim that a (class) unbalanced data set has a negative effect on the performance of LDA. In addition, re-balancing affects the performance of LDA for data sets with either equal or unequal covariance matrices, indicating that having unequal covariance matrices is not a key reason for the difference in performance between original and re-balanced data
Spin domain formation in spinor Bose-Einstein condensation
The spatial structure of the spinor Bose-Einstein condensates with the spin
degrees of freedom is analyzed based on the generalized Gross-Pitaevskii
equation (GP) in the light of the present spin domain experiment on m_F=\pm 1,
and 0 of the hyperfine state F=1 of ^{23}Na atom gases. The GP solutions in
three- and one-spatial dimensional cases reproduce the observed spin domain
structures, revealing the length scale associated with the existence of the
weak interaction of the spin-spin channel, other than the ordinary coherence
length related to the density-density channel. The obtained domain structure in
GP is compared with the result in Thomas-Fermi approximation. The former
solution is found to better describe the observed features than the latter.Comment: 9 pages, 14 figure
Bistability and macroscopic quantum coherence in a BEC of ^7Li
We consider a Bose-Einstein condensate (BEC) of in a situation where
the density undergoes a symmetry breaking in real space. This occurs for a
suitable number of condensed atoms in a double well potential, obtained by
adding a standing wave light field to the trap potential. Evidence of
bistability results from the solution of the Gross-Pitaevskii equation. By
second quantization, we show that the classical bistable situation is in fact a
Schr\"odinger cat (SC) and evaluate the tunneling rate between the two SC
states. The oscillation between the two states is called MQC (macroscopic
quantum coherence); we study the effects of losses on MQC.Comment: 8 pages, 11 figures. e-mail: [email protected]
Prospects for p-wave paired BCS states of fermionic atoms
We present theoretical prospects for creating p-wave paired BCS states of
magnetic trapped fermionic atoms. Based on our earlier proposal of using dc
electric fields to control both the strength and anisotropic characteristic of
atom-atom interaction and our recently completed multi-channel atomic collision
calculations we discover that p-wave pairing with K and Rb
in the low field seeking maximum spin polarized state represent excellent
choices for achieving superfluid BCS states; and may be realizable with current
technology in laser cooling, magnetic trapping, and evaporative/sympathetic
cooling, provided the required strong electric field can be applied. We also
comment on the prospects of similar p-wave paired BCS states in Li, and
more generally on creating other types exotic BCS states. Our study will open a
new area in the vigorous pursuit to create a quantum degenerate fermionic atom
vapor.Comment: to be publishe
First and Second Sound Modes of a Bose-Einstein Condensate in a Harmonic Trap
We have calculated the first and second sound modes of a dilute interacting
Bose gas in a spherical trap for temperatures () and for
systems with to particles. The second sound modes (which exist
only below ) generally have a stronger temperature dependence than the
first sound modes. The puzzling temperature variations of the sound modes near
recently observed at JILA in systems with particles match
surprisingly well with those of the first and second sound modes of much larger
systems.Comment: a shorten version, more discussions are given on the nature of the
second sound. A long footnote on the recent work of Zaremba, Griffin, and
Nikuni (cond-mat/9705134) is added, the spectrum of the (\ell=1, n_2=0) mode
is included in fig.
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