Inversion in magneto-optical effects

Magnetically induced birefringence and dichroism in certain colloidal suspensions exhibit inversion in sign of the effect. The paper discusses various mechanisms which may give rise to such effects. Methods are suggested to trace origin of such inversions. Certain theoretical and experimental results are also discussed.     

Moderate-dose methotrexate in head and neck cancer

200 mg/m2 methotrexate given intravenously in a running drip for 6 h has been used as an initial adjuvant therapy in 38 patients with advanced head and neck cancer. The response rate is as high as 80%, with 21% achieving complete remission. Histologically, specimens were tumor free in 3 patients. Toxicity in 38 patients included leukopenia (4), mucositis (6) and diarrhea (1). This particular dose of methotrexate appears to be safe and usually does not need leucovorin rescue. Also, when given as initial treatment, it is effective in reduction of tumor bulk. A prolonged randomized trial is essential to determine its role in improving long-term survival.     

Recombinant lys-plasminogen given before, but not after, recombinant tissue-type plasminogen activator markedly improves coronary thrombolysis in dogs: relationship of thrombolytic efficacy with parameters of fibrinolysis

Recombinant tissue-type plasminogen activator (rt-PA) administration rapidly restores blood flow in thrombosed coronary arteries, but coronary arteries often reocclude after initial thrombolysis. This occurs because of the short half-life of rt-PA and rapid increase in plasminogen activator inhibitor (PAI-1) and alpha2-antiplasmin levels in plasma. We hypothesized that administration of lys-plasminogen, which binds to fibrin with 10 times greater affinity and results in a loose fibrin structure (as compared with native glu-plasminogen), before rt-PA would enhance the thrombolytic efficacy of rt-PA and modulate parameters of fibrinolysis. To examine this hypothesis, dogs with electrically induced stable thrombus in the left anterior descending coronary artery (LAD) were treated with saline (group A, n = 9) or lys-plasminogen (group B, 2 mg/kg, n = 5), followed 10 min later by rt-PA (1 mg/kg in 20 min). Four other dogs with occlusive LAD thrombus were first given rt-PA, followed by lys-plasminogen (2 mg/kg) 50 min later (group C). Lys-plasminogen given before rt-PA restored flow in all dogs in 14 +/- 4 min (vs. 22 +/- 9 min in group A, p < 0.05), continuing > 2 h (vs. 41 +/- 15 min in group A, p < 0.02). Lys-plasminogen given after rt-PA did not potentiate the effect of rt-PA. Plasma t-PA antigen concentrations were highest in group B dogs at 2 h after rt-PA infusion. PAI-1 and alpha2-antiplasmin plasma levels were suppressed in all dogs receiving lys-plasminogen whether it was given before or after rt-PA. Therefore, lys-plasminogen given before rt-PA markedly potentiates the effect of rt-PA and alters the parameters of fibrinolysis. In contrast, lys-plasminogen given after rt-PA does not influence the thrombolytic effect of rt-PA, whereas it suppresses PAI-1 and alpha2-antiplasmin levels in plasma. This study also suggests that binding of plasminogen to the clot is more important than the plasma levels of PAI-1 and alpha2-antiplasmin.     

Noninvasive ventilation in acute respiratory failure

Noninvasive PPV has been employed for decades in patients with chronic respiratory failure. Increasing use in patients with acute respiratory failure is a more recent phenomenon, mainly because of advances in noninvasive interfaces and ventilator modes. Noninvasive PPV delivered by nasal or oronasal mask has been demonstrated to reduce the need for endotracheal intubation, decrease lengths of stay in the ICU and hospital, and possibly reduce mortality. In the acute care setting, evidence now demonstrates the efficacy of noninvasive PPV for acute exacerbations of COPD, pulmonary edema, pulmonary contusions, and acute respiratory failure in patients who decline or who are not believed to be candidates for intubation. No firm conclusions can yet be made regarding patients with respiratory failure due to other causes, but studies suggest that noninvasive PPV may also be of benefit in patients with postoperative respiratory insufficiency, chest wall disease, and cystic fibrosis. Several factors are vital to the success of this therapy, including careful patient selection, properly timed intervention, a comfortable, well-fitting interface, patient coaching and encouragement, and careful monitoring. Noninvasive ventilation should be used as a way to avoid endotracheal intubation rather than as an alternative. Accordingly, a trial of noninvasive ventilation should be instituted in the course of acute respiratory failure before respiratory arrest is imminent, to provide ventilatory assistance while the factors responsible for the respiratory failure are aggressively treated. Moreover, the authors favor conservative management with expeditious intubation in patients who have other conditions that place them at risk during use of noninvasive ventilation or in patients failing to respond to noninvasive PPV. Noninvasive PPV clearly represents an important addition to the techniques available to manage patients with acute respiratory failure; however, because most studies have been retrospective and uncontrolled, many issues remain unresolved. Further controlled studies are needed to confirm the safety and efficacy of noninvasive PPV, evaluate the most appropriate selection of patients and timing of intervention, define the best type of interface, and assess the costs of noninvasive PPV in comparison with conventional therapy.     

Angiotensin-converting enzyme inhibitor-induced pancreatitis

Approximately 2% of pancreatitis in adults is drug induced. Although some angiotensin-converting enzyme (ACE) inhibitors have been associated with pancreatitis, to the knowledge of the authors this is the first reported case involving benazepril. This case report presents laboratory- and image-proven pancreatitis in a noninsulin dependent 70-year-old man. The patient took benazepril at three different times and experienced the same epigastric symptoms 30 min after each dose. Possible mechanisms are reviewed. Clinicians should strongly consider discontinuing ACE inhibitors, including benazepril, in patients with pancreatitis of no identifiable source.     

Effect of ramp rates during rapid thermal annealing of ion implanted boron for formation of ultra-shallow junctions

Over the last couple of years, manufacturers of rapid thermal annealing (RTA) equipment have been aggressively developing lamp-based furnaces capable of achieving ramp-up rates of the order of hundreds of degrees per second. One of the driving forces for such a strategy was the experimental demonstration of 30 nm p-type junctions using a ≈400°C/s ramp-up rate during a spike-anneal (zero soak-time at temperature). It was proposed that the ultra-fast ramp-up was suppressing transient enhanced diffusion (TED) of boron caused by implantation damage. Ultra-fast ramp rate capability was thus embraced as an essential requirement for the next generation of RTA equipment. In this paper, we review more recent experimental data examining the effect of the ramp-up rate during spike- and soak-anneals on enhanced diffusion and ultra-shallow junction formation. The advantage of increasing the ramp-up rate (above ≈50°C/s) is found to be appreciable only during spike-anneals of the shallowest implants. Since TED naturally decreases with decreasing implantation depth, it follows that the observed advantage of a fast ramp-up does not arise from a so-called suppression of TED but from a straightforward reduction of the thermal budget. Since the temperature ramp-down is in practice limited to a rate much smaller than the achievable ramp-up rates (≈75°C/s vs. ≈400°C/s, respectively), a point of diminishing return is quickly reached when attempting to decrease dopant diffusion by increasing the ramp-up rate only. The advantage of a fast ramp-up is similarly mitigated by the finite minimum soak-time achievable in practice, as well as by decreased process control at faster ramp-up rates. While it is apparent that spike-anneals can minimize dopant diffusion while maximizing dopant activation we find that some of the advantages offered by fast ramp-up rates can be duplicated via modification of the implantation parameters. A survey of spike-anneal daa from different sources supports this point.     

Chiloscyllium plagiosum low-density lipoprotein receptor: evolutionary conservation of five different functional domains

All five functional domains of the low-density lipoprotein (LDL) receptor were assembled in their modern form more than 450 million years ago, as revealed from the cloning and sequencing of an LDL receptor cDNA from Chiloscyllium plagiosum (banded cat shark). The shark LDL receptor has the same overall architecture as the mammalian and amphibian counterparts. Each of the seven cysteine-rich repeats in the ligand binding domain resembles its counterpart in the human LDL receptor more than it does the other repeats in the shark receptor as suggested by the presence of unique signature sequences, indicating that these repeats had already acquired their independent structures by the time of shark development. Furthermore, amino acid sequences of the entire ligand binding domain of shark LDL receptor show 35% identity over a stretch of 294 residues with a Lymnaea stagnalis G-protein-linked receptor (LSGLR). The region of homology between these unrelated proteins includes conservation of most of the unique characteristics of the cysteine-rich repeats of LDL receptor at the expected positions in LSGLR. The results presented are consistent with the hypothesis that all seven repeats in the ligand binding domain of LDL receptor may have been lifted directly from an ancestral gene instead of being evolutionary duplications of a single repeat recruited by the primitive LDL receptor from another gene.     

Frequency response requirements for fluctuating wind pressure measurements

The frequency response requirements for measuring fluctuating wind pressures were examined by analysing full scale data collected at the Texas Tech Wind Engineering Field Research Laboratory It was found that mean peak pressures adjacent to separation and reattachment points were attenuated when the instrumentation frequency response was below 10 Hz for mean wind speeds of 10 m/s. This corresponds to a full scale wavelength of 1 m. For pressures away from these regions and for area-averaged pressures, the cut-off wavelength was higher. A reasonable collapse of the available data for response ratios under separated flow was obtained indicating that attenuation of mean peak pressures could be expected for V/n_cB>0.1 (mean reference velocity V, cut-off frequency n_c and smallest building plan dimennsion B). These findings have implications for the frequency response of wind tunnel model studies investigating peak pressure distributions.     

Measuring the robustness of neighbourhood business districts

A key component of vibrant urban neighbourhoods is the neighbourhood business district (NBD) – the place for amenities, shopping, social engagement and recreation. In order to provide these advantages and be competitive with big box and online retailers, the NBD must be easily accessible and provide a basic range of goods and services. Yet few tools exist that measure both the access and completeness of amenities on NBDs. This paper presents a systematic analysis and provides cities with a tool to assess NBDs and create policies and programmes to support more complete, robust and useful neighbourhood business districts.