On prefilters for digital FIR filter design

A new family of digital prefilter structures is introduced, based on the Dolph-Chebyshev function. These prefilters can be combined with appropriately designed "equalizer" filters based on equiripple methods, leading to efficient FIR digital filter designs. Design examples are included, demonstrating the simplicity of the resulting designs, as compared to conventional equiripple designs

Helicopter rotor loads using matched asymptotic expansions: User's manual

Computer programs were developed to implement the computational scheme arising from Van Holten's asymptotic method for calculating airloads on a helicopter rotor blade in forward flight, and a similar technique which is based on a discretized version of the method. The basic outlines of the two programs are presented, followed by separate descriptions of the input requirements and output format. Two examples illustrating job entry with appropriate input data and corresponding output are included. Appendices contain a sample table of lift coefficient data for the NACA 0012 air foil and listings of the two programs

Helicopter rotor loads using discretized matched asymptotic expansions

The numerical practicality of a matched asymptotic expansion approach for the computation of unsteady three dimensional airloads on a helicopter rotor was improved. This effort utilizes a discretized repesentation of the doublet strength distribution and helical streamlines to decrease the computational requirements of the original analysis. The continuous variation of the doublet strength was approximated by piecewise constant or piecewise quadratic distributions, and the helical trajectory of a fluid particle was approximated by connected straight line segments. As a direct result of these simplified representations the computational time required for the execution of a typical flight condition was reduced by an order of magnitude with respect to the requirements of the original analysis. Airloads which were computed using the discretized method for a two bladed model rotor and a full scale four bladed rotor are in close agreement with measured results and airloads from the original asymptotic analysis. For conditions characterized by significant rotor/wake interaction the piecewise constant representation requires a reduced azimuth spacing to maintain acceptable accuracy

Insights into the Conformation of Aminofluorene-Deoxyguanine Adduct in a DNA Polymerase Active Site

The active site conformation of the mutagenic fluoroaminofluorene-deoxyguanine adduct (dG-FAF, N-(2′-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene) has been investigated in the presence of Klenow fragment of Escherichia coli DNA polymerase I (Kfexo−) and DNA polymerase β (pol β) using 19F NMR, insertion assay, and surface plasmon resonance. In a single nucleotide gap, the dG-FAF adduct adopts both a major-groove- oriented and base-displaced stacked conformation, and this heterogeneity is retained upon binding pol β. The addition of a non-hydrolysable 2′-deoxycytosine-5′-[(α,β)-methyleno]triphosphate (dCMPcPP) nucleotide analog to the binary complex results in an increase of the major groove conformation of the adduct at the expense of the stacked conformation. Similar results were obtained with the addition of an incorrect dAMPcPP analog but with formation of the minor groove binding conformer. In contrast, dG-FAF adduct at the replication fork for the Kfexo− complex adopts a mix of the major and minor groove conformers with minimal effect upon the addition of non-hydrolysable nucleotides. For pol β, the insertion of dCTP was preferred opposite the dG-FAF adduct in a single nucleotide gap assay consistent with 19F NMR data. Surface plasmon resonance binding kinetics revealed that pol β binds tightly with DNA in the presence of correct dCTP, but the adduct weakens binding with no nucleotide specificity. These results provide molecular insights into the DNA binding characteristics of FAF in the active site of DNA polymerases and the role of DNA structure and sequence on its coding potential

3-[211At]astato-4-fluorobenzylguanidine: a potential therapeutic agent with prolonged retention by neuroblastoma cells.

An analogue of meta-iodobenzylguanidine (MIBG) in which an aromatic hydrogen was replaced with fluorine has been found to possess many properties similar to those of the parent compound. Moreover, 4-fluoro-3-iodobenzylguanidine (FIBG) was retained in vitro by human neuroblastoma cells to a much greater extent than MIBG itself. Since alpha-emitters such as 211At could be valuable for the treatment of micrometastatic disease, an FIBG analogue in which the iodine atom is replaced by 211At would be of interest. In this study, we have evaluated the in vitro and in vivo properties of 3-[211At]astato-4-fluorobenzylguanidine ([211At]AFBG). The specific binding of [211At]AFBG to SK-N-SH human neuroblastoma cells remained fairly constant over 2- to 3-log activity range and was similar to that of [131I]MIBG. The uptake of [211At]AFBG by this cell line was reduced by desipramine, ouabain, 4 degrees C incubation, noradrenaline, unlabelled MIBG and FIBG, suggesting that its uptake is specifically mediated through an active uptake-1 mechanism. Over the 16 h period studied, the amount of [211At]AFBG retained was similar to that of [131I]FIBG, whereas the per cent of retained meta-[211At]astatobenzylguanidine ([211At]MABG) was considerably less than that of [131I]FIBG (53% vs 75%; P < 0.05). The IC50 values for the inhibition of uptake of [131I]MIBG, [211At]MABG, [125I]FIBG and [211At]AFBG by unlabelled MIBG were 209, 300, 407 and 661 nM respectively, suggesting that the affinities of these tracers for the noradrenaline transporter in SK-N-SH cells increase in that order. Compared with [211At]MABG, higher uptake of [211At]AFBG was seen in vivo in normal mouse target tissues such as heart and, to a certain extent, in adrenals. That the uptake of [211At]AFBG in these tissues was related to the uptake-1 mechanism was demonstrated by its reduction when mice were pretreated with desipramine. However, the stability of [211At]AFBG towards in vivo dehalogenation was less than that of [211At]MABG, as evidenced by the higher uptake of 211At in thyroid, spleen, lungs and stomach

Klippel-Feil syndrome – the risk of cervical spinal cord injury: A case report

BACKGROUND: Klippel-Feil syndrome is defined as congenital fusion of two or more cervical vertebrae and is believed to result from faulty segmentation along the embryo's developing axis during weeks 3–8 of gestation. Persons with Klippel-Feil syndrome and cervical stenosis may be at increased risk for spinal cord injury after minor trauma as a result of hypermobility of the various cervical segments. Persons with Klippel-Feil Syndrome often have congenital anomalies of the urinary tract as well. CASE PRESENTATION: A 51-year male developed incomplete tetraplegia in 1997 when he slipped and fell backwards hitting his head on the floor. X-rays of cervical spine showed fusion at two levels: C2 and C3 vertebrae, and C4 and C5 vertebrae. Intravenous urography (IVU) revealed no kidneys in the renal fossa on both sides, but the presence of crossed, fused renal ectopia in the left ilio-lumbar region. This patient had a similar cervical spinal cord injury about 15 years ago, when he developed transient numbness and paresis of the lower limbs following a fall. DISCUSSION AND CONCLUSION: 1) Persons with Klippel-Feil syndrome should be made aware of the increased risk of sustaining transient neurologic deterioration after minor trauma if there is associated radiographic evidence of spinal stenosis. 2) Patients with Klippel-Feil syndrome often have congenital anomalies of the urinary tract. Our patient had crossed, fused, ectopia of kidney. 3) When patients with Klippel-Feil syndrome sustain tetraplegia they have increased chances of developing urinary tract calculi. Treatment of kidney stones may pose a challenge because of associated renal anomalies. 4) Health professionals caring for cervical spinal cord injury patients with Klippel-Feil syndrome and renal anomalies should place emphasis on prevention of kidney stones. A large fluid intake is recommended for these patients, as a high intake of fluids is still the most powerful and certainly the most economical means of prevention of nephrolithiasis

Localisation of [131I]MIBG in nude mice bearing SK-N-SH human neuroblastoma xenografts: effect of specific activity.

The biodistribution of no-carrier-added (n.c.a.) meta-[131I]iodobenzylguanidine ([131I]MIBG) and that prepared by the standard isotopic exchange method were compared in athymic mice bearing SK-N-SH human neuroblastoma xenografts. No advantage in tumour uptake was observed for the n.c.a. preparation. BALB/c nu/nu mice exhibited lower uptake in highly innervated normal tissues (heart and adrenals) than normal BALB/c mice. In another experiment, the distribution of n.c.a. [131I]MIBG in the absence or presence (3-9 micrograms) of MIBG carrier was determined. At both 4 h and 24 h, the heart uptake was reduced by a factor of 1.5 even at a dose of 3 micrograms MIBG. Tumour uptake was not significantly altered by various amounts of unlabelled MIBG at either time point

Knowns and unknowns for psychophysiological endophenotypes: Integration and response to commentaries

We review and summarize seven molecular genetic studies of 17 psychophysiological endophenotypes that comprise this special issue of Psychophysiology , address criticisms raised in accompanying Perspective and Commentary pieces, and offer suggestions for future research. Endophenotypes are polygenic, and possibly influenced by rare genetic variants. Because they are not simpler genetically than clinical phenotypes, they are unlikely to assist gene discovery for psychiatric disorder. Once genetic variants for clinical phenotypes are identified, associated endophenotypes are likely to provide valuable insights into the psychological and neural mechanisms important to disorder pathology. This special issue provides a foundation for informed future steps in endophenotype genetics, including the formation of large sample consortia capable of fleshing out the many genetic variants contributing to individual differences in psychophysiological measures.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109647/1/psyp12358.pd

Diaphragmatic fenestration an effective treatment for refractory postoperative chylothorax: a case report

Postoperative chylothorax remains a clinical challenge to the surgeon with substantial morbidity and risk of mortality. Though an uncommon complication, it is known to complicate cardiac and non-cardiac thoracic surgeries. Conservative measures are first employed in managing this. Surgical options are adopted when the effusion is protracted, most recent of which includes diaphragmatic fenestration. A 9-year-old girl is presented who developed recurrent right chylothorax following thoracoscopic excision of a cystic lymphangioma. Following failed conservative therapy, she had thoracic duct ligation and right diaphragmatic fenestration (using fenestrated polytetrafluoroethylene patch) with satisfactory outcome. Aetio-pathologic mechanisms implicated in postoperative chylothorax have been classified into traumatic (iatrogenic injury to the thoracic duct or its branches) and non-traumatic. With initial conservative measures (repeated pleural aspirations and intercostal drainage, medium chain triglyceride/ low fat feeds or alternatively, fasting and total parenteral nutrition) spontaneous closure remains unpredictable. Diaphragmatic fenestration when employed resulted in faster resolution of effusion and earlier commencement of enteral feeding with no significant complication. Diaphragmatic fenestration is effective and safe for treating refractory post-operative chylothorax