Top Loop Research Articles

Botulin Toxin in the Treatment of Nonrelaxing Puborectalis Syndrome

Purpose: To evaluate the results of botulin toxin injection in the external anal sphincter for the treatment of nonrelaxing puborectalis syndrome. Method: 15 patients (13 women, 2 men; aged 36–48 years) were treated with botulinum A toxin injection, using a dose of 25 IU diluted in 1 ml normal saline injected into the top loop of the external anal sphincter at the 3 and 9 o’clock positions. The mean follow-up period was 14.6 ± 3.3 (SD) months. Results: Two patients did not respond to the treatment while improvement occurred in 13. Straining at defecation disappeared and stool frequency was normalized. Improvement was maintained for a mean of 4.8 ± 1.4 SD months, after which time reinjection needed to be done. No adverse side effects were encountered. Conclusions: Botulin toxin injection is a simple, easy and safe method for the treatment of nonrelaxing puborectalis syndrome. It is to be considered after biofeedback has failed.

Porin polypeptide contributes to surface charge of gonococci.

Each strain of Neisseria gonorrhoeae elaborates a single porin polypeptide, with the porins expressed by different strains comprising two general classes, Por1A and Por1B. In the outer membrane, each porin molecule folds into 16 membrane-spanning beta-strands joined by top- and bottom-loop domains. Por1A and Por1B have similar membrane-spanning regions, but the eight surface-exposed top loops (I to VIII) differ in length and sequence. To determine whether porins, and especially their top loop domains, contribute to bacterial cell surface charge, strain MS11 gonococci that were identical except for expressing a recombinant Por1A, Por1B, or mosaic Por1A-1B polypeptide were compared by whole-cell electrophoresis. These porin variants displayed different electrophoretic mobilities that correlated with the net numbers of charged amino acids within surface-exposed loops of their respective porin polypeptides. The susceptibilities of porin variants to polyanionic sulfated polymers correlated roughly with gonococcal surface charge; those porin variants with diminished surface negativity showed increased sensitivity to the polyanionic sulfated compounds. These observations indicate that porin polypeptides in situ contribute to the surface charge of gonococci, and they suggest that the bacterium's interactions with large sulfated compounds are thereby affected.

Involvement of the M7/M8 Extracellular Loop of the Sodium Pump α Subunit in Ion Transport: STRUCTURAL AND FUNCTIONAL HOMOLOGY TO P-LOOPS OF ION CHANNELS

Mutations were introduced in the motif 884DDRW887 from an extracellular peptide of the sodium pump alpha subunit localized between M7 and M8 membrane spans to investigate a possible role of this structure in ion recognition. A homologous sequence 399QDCW402 that occurs in the P-loops of Na+ channels was shown earlier to be important for ion gating. Mutant sodium pumps were expressed in yeast and subsequently investigated for their behavior toward ouabain, Na+, K+, and ATP. Native enzyme and D884A, D884R, D885A, D885E, or D885R mutants all bind ouabain in the presence of phosphate and Mg2+. The KD values determined from Scatchard analysis are in the range 5-8 nM for the native enzyme and the D884A, D885E, or D885A mutants, and 15.7 +/- 2.04 and 30.1 +/- 4.32 nM for mutants D884R and D885R, respectively. This ouabain binding is reduced in the presence of K+ in a similar way for both native or mutant sodium pumps with relative affinities (K0.5) for K+ ranging from 1.4 to 3.7 mM. Ouabain binding in the presence of 100 microM ATP is promoted by Na+ with K0.5 = 1.64 +/- 0.01 mM for the native enzyme and K0.5 = 8. 6 +/- 1.35 mM for the D884R mutant. The K0.5 values of the two enzymes for ATP are 0.66 +/- 0.16 microM and 1.1 +/- 0.12 microM, respectively. Ouabain binding as a function of Na+ concentration, on the other hand, is very low for the D885R mutant, even at an ATP concentration of 2 mM. Phosphate or eosin, however, are recognized by this mutant enzyme, so that a major conformational change within the ATP-binding site appears unlikely. The inability of the D885R mutant to bind ouabain in the presence of Na+ and ATP could be explained by assuming that the M7/M8 connecting extracellular loop, which also contains the mutated amino acids, is invaginated within the plane of the plasma membrane and possibly involved in acceptance and/or release of Na+ ions coming from cytosolic areas of the protein. In this case, the placement of an additional positive charge might repel Na+ ions and interrupt their flow, thus not allowing the enzyme to assume the proper conformational state for ouabain binding. Such invaginated hydrophilic protein structures, such as the P-loops of Na+ and K+ channels, are already known and have been shown to participate in ion conduction.

Performance Evaluation of Ideal Heat Integrated Distillation Columns.

In order to understand the operating feasibility of the ideal heat integrated distillation column (HIDiC), its control systems are studied in both time and frequency domains with respect to three operating conditions (i.e., feed thermal condition, q q = 0.5 and q > 0.5). It was found that the ideal HIDiC could be operated quite smoothly under all these operating conditions. However, the strongest interaction between top and bottom control loops is observed at q=0.5, and the system resilience may be degraded when q strays from 0.5 because of the strong gain directionality of the process.The feed location also strongly affects the dynamic performance of the ideal HIDiC. Placing feed in the middle of the process could intensify the interaction between the top and bottom control loops. Therefore, the determination of both feed thermal condition and feed location should be based on a careful compromise between steady state energy saving and dynamic resiliency of the system.

Determining Appropriate Configuration of Ideal Heat Integrated Distillation Columns(HIDiC).

The major concern in developing various kinds of heat integrated distillation columns is the strong interaction and high sensitivity resulting from heat integration (Takamatsu, 1996), which could drastically deteriorate system potential performance. Hence, it is of great importance to design processes so as to make these undesired properties as small as possible, namely to increase system dynamic resilience. As for the ideal heat integrated distillation column (HIDiC), we already know that its symmetrical specifications, such as equal feed split, middle feed location and same structures between rectifying and stripping sections, are the main reasons for strong interaction between top and bottom control loops (Huang et al, 1996). In order to make the ideal HIDiC have higher dynamic resilience, these kinds of symmetrical specifications should be deleted. A previous work (Huang et al, 1996) already explored how to improve the system resilience through appropriately assigning feed thermal condition q and feed location under general configuration of the ideal HIDiC. As to the effects of symmetrical structure between rectifying and stripping sections, its effects are still not clear. In this work we will concentrate on this problem by studying three possible configurations of the ideal HIDiC. Both time and frequency domain techniques have been employed to assess the potential effects of system configuration towards system performances, and the results obtained are further evaluated through rigorous nonlinear closed-loop simulation.

Symmetry breaking induced by top quark loops from a model without scalar mass

Considering the standard model as an effective electroweak theory, in which we have no scalar mass term in the Higgs potential ( μ 2 = 0), we show that the spontaneous symmetry breaking of SU(2) L × U(1) can be induced by top loops. The Higgs boson mass obtained is smaller than 300 GeV.

Dynamics of ideal heat integrated distillation columns.

An ideal heat integrated distillation column (HIDiC), which has neither a reboiler nor a condenser, was studied based on its non-linear and linearized dynamic models. It was found that heat integration between rectifying and stripping sections does not lead to an unstable plant. Moreover, the thermal interaction appears to be relatively stronger at low pressure difference than that at high pressure difference.Strong gain directionality has been found in the ideal HIDiC, where the pressure difference and feed thermal condition correspond to low and high gain direction respectively. With proper design of the process, thermal interaction, affects the system time constant only to a limited extent, and intensifies the interaction within a dual point composition control scheme. In fact, the degree of coupling between top and bottom control loops is governed by feed thermal condition since it is in line with high gain direction and can simultaneously introduce changes of both internal and external flows.

Top-induced electroweak breaking in the minimal supersymmetric standard model

Severe constraints on parameters of the minimal supersymmetric standard model follow from a dynamical electroweak symmetry breaking mechanism dominated by top and stop loops. In particular, the lightest Higgs boson mass is expected to be smaller than 100 GeV.

Experimental and analytical studies on the multi-surface sloshing characteristics of a top entry loop type FBR

For a system with multiple vessels which have a free liquid surface and are connected with inverted U-shaped piping, it is important to establish a highly accurate technique of evaluating the sloshing behavior that occurs in the multiple liquid surface system when an earthquake strikes. In the present study, a series of vibration tests were conducted to clarify the basic characteristics of sloshing using parameters such as the in-vessel structure, multi-surface connection, in-vessel flow, and so forth. For testing, a 1 8 scale model of the top entry loop type FBR primary loop was used. Further, the applicability of the analytical code was evaluated, and the code was found to estimate the mode shape and natural frequency of sloshing with high accuracy.

Practical Control Methods for Distillation Columns Using Neural Networks

The use of artificial neural networks in SISO IMC structure to control the top column composition is exploited. Here nonlinear process model is replaced by a neural network and its inverse is also incorporated to improve the control action. An IMC multiloop structure is also tested where only top loop includes a neural compensation. The gain variation law of the system is learned by a neural network which serves to adapt this parameter in the internal model and the controller of the IMC scheme. The bottom loop is implemented as a conventional IMC design. This technique can be seen as a feedforward compensation for nonlinearities and gives better performance comparing with the overall linear IMC design. Another control structure using the neural network inverted plant model is combined with a feedback control structure implemented with traditional P, PI and PD controllers is analyzed in this work. This last methodology presents a very good performance depending on which classical controller is used. Concluding the paper a set of validation tests are carried out, via digital simulations, for step variations of the reference and load variables.

Development of the demonstration FBR and its commercialization

The FBR being developed in Japan is expected to operate commercially by the year 2030 or so. The construction of the first demonstration FBR “DFBR-1”, which follows the experimental FBR “JOYO” and the prototype FBR “MONJU” is scheduled for early 2000s. The Atomic Energy Commission adopted these policies in the new version of “The Long Term Program for Research, Development and Utilization of Nuclear Energy”. The Japan Atomic Power Company has progressed design studies of the DFBR-1 and R&Ds. Electric utilities settled the major design specifications of the DFBR-1 such as the top entry loop type as the reactor type and about 660 MWe of plant capacity. To achieve the goals for the commercialization of FBRs, such as a high level of safety and reliability comparable with a LWR and further improvement of economy, many innovative technologies and system improvements will be required in commercial FBRs. This paper describes the present status of development of the DFBR-1.

Aspects of the electroweak phase transition in the minimal supersymmetric standard model

We study the finite-temperature effective potential of the Minimal Supersymmetric Standard Model in the full ( m A , tan β) parameter space. As for the features of the electroweak phase transition, we identify two possible sources of significant differences with respect to the Standard Model: a stop sector with little supersymmetry breaking makes the phase trasition more strongly first-order, whereas a light CP-odd neutral boson weakens its first-order nature. After including the leading plasma effects, T = 0 radiative corrections due to top and stop loops, and the most experimental constraints, we find that the danger of washing out any baryon asymmetry created at the electroweak scale is in general no less than in the Standard Model.

Radiative corrections to the decay H → hh in the minimal supersymmetric standard model

We set up a suitable renormalization programme for the one-loop computation of the decay rate Γ( H → hh) in the minimal supersymmetric extension of the standard model. We then perform an explicit diagrammatic calculation, including the full contributions from top, bottom, stop and sbottom loops. We find that, for tan β close to 1 and m H ⪆ 2m t , the results can significantly differ from those previously obtained in the effective potential approach. However, the latter method remains a good approximation in the region of parameter space which is most relevant for H searches at large hadron colliders.

Upper Bound of the Lightest Higgs Boson Mass in the Minimal Supersymmetric Standard Model

In the minimal supersymmetric standard madel, it is shown that a radiative correction of the top and stop loops gives a finite, but non-negligible contribution to Higgs scalar masses if m, ' 150-250 GeV. The upper limit to the lightest-scalar mass becomes 70-190 GeV in the range of heavy top quark. 1 The mechanism of electroweak symmetry breaking is one of the most important issues in the present particle physics_ In the standard electroweak model a funda­ mental Higgs doublet is introduceq to cause the spontaneous symmetry breaking. Supersymmetry (SUSY), eliminating all quadratic divergences, may provide a better theoretical basis to describe a fundamental Higgs boson with a relatively small mass to a high energy cutoff scale, say the Planck scale for example. I) In the minimal SUSY extension of the standard electroweak model the Higgs sector consists of two chiral superfields of Higgs doublets (/JHl and (/JH2 with opposite hypercharges. They are required to give masses for all quarks and leptons and to guarantee the ~bsence of the gauge anomaly. Five physical Higgs bosons among them survive the gauge symmetry breaking, namely, there appear two neutral scalars rpa and rpb, a neutral pseudoscalar X and a pair of charged scalars x± as physical particles. It has been, furthermore, shown by many authors 2 ) that there is at least one neutral scalar boson lighter than ZO(m<p< mzo) in the minimal SUSY model. This has strongly motivated many recent analyses of Higgs boson production at LEP energies. 3 ) In this paper, however, we stress that a radiative correctiQn gives a significant contribution to the Higgs mass term if the top quark is 8uficiently heavy as mt ~150-250 GeV. Therefore, the presence of the Higgs scalar lighter than mzo is not an inevitable prediction of the minimal SUSY standard model. Let us discuss the Higgs sedor in the minimal SUSY model. With general soft-breaking terms 4 ) of SUSY the tree-level Higgs potential is given by

Sequence and secondary structure analysis of the 5′-terminal region of flavivirus genome RNA

The 5′-terminal noncoding region sequences were determined for the genome RNAs of seven strains of St. Louis encephalitis virus (SLEV) and one strain of West Nile virus (WNV) using a single synthetic cDNA primer complementary to the 5′-terminus of the coding region of a strain of WNV RNA. The 5'-terminal sequences obtained for the SLEV and WNV RNAs were compared with published sequences for yellow fever virus (YFV), Murray Valley encephalitis virus (MVEV), and dengue virus. While only short regions within the 5′-noncoding sequence were conserved among different flavivirus RNAs, significant homology was observed in this region among members of the same flavivirus subgroup and almost complete conservation was observed between different strains of the same virus. For example, seven strains of SLE, isolated from different geographic locations over a 17-year period and differing in their neurovirulence phenotype, contained only two to four nucleotide changes in the 5′-noncoding region. Interestingly, each of three low-virulence strains shared the same unique base substitution at position 16. Secondary structures predicted to be formed by the 5′-termini of each of the different flavivirus genome RNAs were of similar size and shape, in each case consisting of a stem with a small top loop and a larger side loop. The prediction of a common structure among a number of different flaviviruses, despite the lack of extensive sequence homology, suggests that this secondary structure is functionally important. An additional stem and loop structure is predicted to be formed in the region spanning the translation initiation codon. This structure showed significantly less conservation of size and shape than the 5′-terminal secondary structure.

Depth-Dependent Character of Extended Defects in Ion-Implanted and RTA'd Si

ABSTRACTThe character of extended defects formed in high-energy S-ion implanted and rapid thermal annealed (RTA'd) Si has been found by transmission electron microscopy (TEM) to be dependent on the depth at which the defects have formed in the ion-implanted regions. Si implanted with 6 MeV S-ions and RTA'd at 1000°C for 10 s showed a buried layer of extended defects with unfaulted loops towards the top and faulted loops towards the bottom. At higher S fluences, all the loops were unfaulted, some loops coalesced to form a dislocation network, and SiS precipitates were formed. At higher RTA temperatures, all the loops were unfaulted. A few possibilities that could explain the difference in defect character will be discussed.

Self-Tuning Control of a Binary Distillation Column — A Simulation Test Care

In this simulation study, a nine-trays binary distillation column is dealt with. The classical regulation scheme consisting of two controllers located at the bottom and top of the column is considered. An analog P.I.D. is taken as bottom controller, whereas a number of digital controllers are used in the top feedback loop. The digital controllers are based on SISO Self-Tuning Concepts. Precisely, the control performances achieved by the Minimum Variance, Model Following and Detuned Minimum Variance approaches are compared. Finally, the robustness improvement obtained with a time-varying forgetting factor is discussed.