Imaging modalities for study of the distal ulnar region

Judicious use of diagnostic imaging maximizes the diagnostic capabilities of the surgeon treating the distal radio-ulnar joint (DRUJ). A good clinical history and clinical examination are necessary to direct the selection of appropriate imaging studies. Plain radiographs are almost always the first imaging examination. More advanced imaging techniques are costly and may provide only limited information. This article discusses imaging modalities useful for assessment of the DRUJ and the area around it.     

Scanning Ion Probe Studies of Silicon Implantation Profiles in AlGaN/GaN HEMT Heterostructures

This paper reports results of scanning ion probe studies of silicon implantation profiles in source and drain regions of AlGaN/GaN high-electron-mobility transistor (HEMT) heterostructures. It is shown that both the undoped channel length and the transition region between implanted and non- implanted regions become wider with increasing depth in the structure. These results may explain the previously reported existence of resistance associated with the transition region between implanted and non-implanted semiconductor regions in AlGaN/GaN HEMT heterostructures with non-alloyed Si-implanted source and drain ohmic contact regions.     

Cardiac effects of adjuvant doxorubicin and radiation therapy in breast cancer patients

PURPOSE: To assess the cardiac effects of two different cumulative doses of adjuvant doxorubicin and radiation therapy (RT) in breast cancer patients. PATIENTS AND METHODS: Two hundred ninety-nine breast cancer patients were prospectively randomized to receive either five cycles (CA5) or 10 cycles (CA10) of adjuvant treatment with cyclophosphamide (500 mg/ m2) and doxorubicin (45 mg/m2) administered by intravenous bolus every 21 days. One hundred twenty-two of these patients also received RT. Estimates of the cardiac RT dose-volume were retrospectively categorized as low, moderate, or high. The risk of major cardiac events (congestive heart failure, acute myocardial infarction) was assessable in 276 patients (92%), with a median follow-up time of 6.0 years (range, 0.5 to 19.4). RESULTS: The estimated risk (95% confidence interval) of cardiac events per 100 patient-years was significantly higher for CA10 than for CA5 [1.7 (1.0 to 2.8) v 0.5 (0.1 to 1.2); P=.02]. The risk of cardiac events in CA5 patients, irrespective of the cardiac RT dose-volume, did not differ significantly from rates of cardiac events predicted for the general female population by the Framingham Heart Study. In CA10 patients, the incidence of cardiac events was significantly increased (relative risk ratio, 3.6; P < .00003) compared with the Framingham population, particularly in groups that also received moderate and high dose-volume cardiac RT. CONCLUSION: Conventional-dose adjuvant doxorubicin as delivered in the CA5 regimen by itself, or in combination with locoregional RT, was not associated with a significant increase in the risk of cardiac events. Higher doses of adjuvant doxorubicin (CA10) were associated with a threefold to fourfold increased risk of cardiac events. This appears to be especially true in patients treated with higher dose-volumes of cardiac RT. Larger studies with longer follow-up periods are needed to confirm these results.     

Sphincter preservation therapy for distal rectal carcinoma: a review

BACKGROUND: There has been increasing interest in the use of sphincter-preserving therapy for patients with distal rectal carcinomas. The outcomes of conservative treatments for early stage rectal carcinoma appear to be comparable to that achieved with abdominoperineal resection. METHODS: Retrospective and prospective clinical series of patients with distal rectal carcinoma treated by local excision alone, local excision with postoperative adjuvant therapy, preoperative radiation followed by local excision, or radical circumferential sphincter-sparing surgeries were reviewed. The local control rates, salvage rates, and treatment complications in patients treated by these various methods were examined. RESULTS: Patients with T1 distal rectal carcinoma with favorable clinical and histopathologic characteristics treated with local excision alone had a local control rate of greater than 90% in most series. Postoperative chemoradiation improved local control for those with T1 disease with unfavorable characteristics, or those with T2 disease. Most T3 patients had failure rates of greater than 30% despite adjuvant local and systemic therapy. With high dose preoperative radiation, approximately 80% of patients with locally advanced or unresectable tumors were able to undergo sphincter-preservation treatment. CONCLUSIONS: Patients with favorable T1 rectal carcinoma are likely to be adequately treated with local excision alone. Patients with T1 disease with unfavorable characteristics as well as T2 patients will benefit from postoperative chemoradiation. The use of local therapy in T3 patients needs to be carefully considered because these patients are at relatively high risk for local recurrence despite adjuvant therapy. Preoperative radiation followed by either local excision or radical circumferential sphincter-sparing resections appears promising in allowing sphincter preservation in patients with locally advanced tumors.     

Taylor ballistic impact modelling applied to deformation and mass loss determinations

Taylor utilized a wave propagation model to analyze the deformation behavior of a ductile cylinder impacting a rigid surface end-on. The Taylor analysis is used to produce simple well behaved models of penetrator and plate deformation due to ballistic impact. In addition, penetrator mass loss by erosion and shear mechanisms is modelled. It is shown that dynamic stress-strain data obtained in a variety of ways can be represented by bi-linear stress-strain relationships. Dynamic yield strengths and work-hardening coefficients for several materials are found to correlate with the Brinell hardness number.     

Differences in platelet alpha-granule release between normals and immune thrombocytopenic patients and between young and old platelets

We studied the effect of central line catheters on thrombus formation in the right atrium (RA), including the incidence and echocardiographic characteristics of the catheter-associated thrombus as well as possible clinical implications in patients. We prospectively studied 55 patients by transesophageal echocardiography within 1 week after Hickman catheter implantation and on a follow-up study at 6 to 8 weeks. We succeeded in imaging the catheter tip in 48 of the 55 patients (87%). In the baseline study 13 had the tip placed in the RA, eight at the superior vena cava-atrium junction, and 27 in the superior vena cava. An abnormal mass, consistent with a thrombus, was found in 12.5% of the patients, all of which were seen within the 13-patient (46%) group with the Hickman catheter tip placed in the RA. Hickman catheter insertion is associated with high incidence (12.5%) of early formation of RA thrombus. The formation of these thrombi is asymptomatic and highly associated (p < 0.001) with the catheter tip position in the RA, in contrast to their positioning in the superior vena cava or in its junction with the right atrium. On the basis of these findings, we recommend that special attention and effort be given to placing of the catheter tip in the superior vena cava and avoiding the RA during the implantation procedure.     

Implantation angle periphery effects on non-alloyed Si-implanted ohmic contacts for AlGaN/GaN high electron mobility transistors

We report on the effect of implantation angle on contact resistance of non-alloyed ohmic contacts to selectively implanted source/drain regions in AlGaN/GaN high electron mobility transistor (HEMT) heterostructures. Three different components of contact resistance are observed for such contacts: (i) contact resistance between the metal and the semiconductor, (ii) resistance of the implanted region and (iii) an additional resistance attributed to a transition region between implanted and non-implanted region. This third component varies strongly with implantation angle. The variation with implantation angle shows that the ratio of lateral implantation damage to penetration depth is critical for implantation of AlGaN/GaN HEMT source/drain contact regions. Our results also show that increasing the implantation angle in combination with reducing the implantation width can reduce contact resistance.     

Injection Molding of Superhydrophobic Liquid Silicone Rubber Surfaces

Superhydrophobic functional surfaces have numerous applications. Their self-cleaning ability and the associated savings in energy, water and cleaning agents enhance the sustainability of products and often make active cleaning of these surfaces unnecessary. Silicone surfaces, which aim to imitate the surface of the lotus plant, were prepared using a microstructured injection mold. The conical micro structures were varied in diameter and height ranging from 5 to 20 $\upmu $ m as were the process parameters within the framework of a statistical experimental plan. The molded structures were evaluated by scanning electron microscopy and confocal laser microscopy, and the resulting contact angle was measured. In contrast to the structural dimensions, the process parameters had only a minor impact on the contact angle. Smaller base diameters of the individual cones and the resulting smaller distances between the cone tips produced larger contact angles. Larger aspect ratios and increasing heights at equal intervals of the individual structures led to smaller standard deviations from the mean measured contact angles. Subsequent mechanical load tests showed the resistance of the functionalization. Our results reveal that it is possible to produce robust superhydrophobic surfaces in a single-step liquid silicone injection molding process.     

Enhancing the Infrared Photoresponse of Silicon by Controlling the Fermi Level Location within an Impurity Band

Strong absorption of sub‐band gap radiation by an impurity band has recently been demonstrated in silicon supersaturated with chalcogen impurities. However, despite the enhanced absorption in this material, the transformation of infrared radiation into an electrical signal via extrinsic photoconductivity—the critical performance requirement for many optoelectronic applications—has only been reported at low temperature because thermal impurity ionization overwhelms photoionization at room temperature. Here, dopant compensation is used to manipulate the optical and electronic properties and thereby improve the room‐temperature infrared photoresponse. Silicon co‐doped with boron and sulfur is fabricated using ion implantation and nanosecond pulsed laser melting to achieve supersaturated sulfur concentrations and a matched boron distribution. The location of the Fermi level within the sulfur‐induced impurity band is controlled by tuning the acceptor‐to‐donor ratio, and through this dopant compensation, three orders of magnitude improvement in infrared detection at 1550 nm is demonstrated.