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The effect of stray fields from the recording layer on the reading and writing process has been studied for a perpendicular recording system. The system consists of a single pole writer with a wide return pole, a conventional spin-valve reader and a double layer recording medium. A writer- and reader-induced asymmetry is observed in the recording process for a dc erased background. The asymmetry is interpreted as stray fields of the dc background giving rise to reader saturation and an offset in the current driven inductive write field. [ABSTRACT FROM AUTHOR]

A focused ion beam (FIB) has been used to trim write heads for perpendicular magnetic recording using untrimmed HGA-level longitudinal heads. The ion-beam imaging of the write head during FIB processing was minimized to limit exposure of the active magnetic material at the ABS to a 30 keV Ga[sup +] ion dose of less than 10[sup 14] Ga[sup +]/cm² (≈10[sup -13] C/µm²) (the GMR reader was never exposed), which is significantly below levels where magnetic properties have been observed to degrade [W. M. Kaminsky et al., Appl. Phys. Lett. 78, 1589 (2001)]. The corresponding recording characteristics and spatial profiles of written tracks have been measured on a spin stand and a magnetic force microscope (MFM). Recording performance, such as SNR, and pulse shape of transitions, for example, as a function of head design and FIB processing is discussed, which compares very favorably to the performance of untrimmed heads. The MFM images reveal curvature in the magnetic transitions (transition smile) when writing with a single-pole writer with a straight trailing edge. Conversely, we demonstrate straight transitions using a single-pole writer with a curved trailing edge. Our results demonstrate the robustness of FIB-trimmed heads down to sub-100-nm length scales. [ABSTRACT FROM AUTHOR]

[FeFe]-hydrogenases (HYDA) link the production of molecular H(2) to anaerobic metabolism in many green algae. Similar to Chlamydomonas reinhardtii, Chlorella variabilis NC64A (Trebouxiophyceae, Chlorophyta) exhibits [FeFe]-hydrogenase (HYDA) activity during anoxia. In contrast to C. reinhardtii and other chlorophycean algae, which contain hydrogenases with only the HYDA active site (H-cluster), C. variabilis NC64A is the only known green alga containing HYDA genes encoding accessory FeS cluster-binding domains (F-cluster). cDNA sequencing confirmed the presence of F-cluster HYDA1 mRNA transcripts, and identified deviations from the in silico splicing models. We show that HYDA activity in C. variabilis NC64A is coupled to anoxic photosynthetic electron transport (PSII linked, as well as PSII-independent) and dark fermentation. We also show that the in vivo H(2)-photoproduction activity observed is as O(2) sensitive as in C. reinhardtii. The two C. variabilis NC64A HYDA sequences are similar to homologs found in more deeply branching bacteria (Thermotogales), diatoms, and heterotrophic flagellates, suggesting that an F-cluster HYDA is the ancestral enzyme in algae. Phylogenetic analysis indicates that the algal HYDA H-cluster domains are monophyletic, suggesting that they share a common origin, and evolved from a single ancestral F-cluster HYDA. Furthermore, phylogenetic reconstruction indicates that the multiple algal HYDA paralogs are the result of gene duplication events that occurred independently within each algal lineage. Collectively, comparative genomic, physiological, and phylogenetic analyses of the C. variabilis NC64A hydrogenase has provided new insights into the molecular evolution and diversity of algal [FeFe]-hydrogenases.

Localizing the acromioclavicular joint can be difficult. Using bony landmarks--the clavicle and the spine of the scapula--the acromioclavicular joint can be consistently localized for physical examination, injections, and surgery.

A case report is presented in which a professional football player, who was 4 years status post anterior cruciate ligament (ACL) reconstruction with autogenous patellar tendon, ruptured his graft. The contralateral patellar tendon was not available as a graft because of a more recent ACL reconstruction using that autogenous patellar tendon. This case reports the use of a previous donor site for supplying a patellar tendon autograft. Biopsy of the donor graft was consistent with normal tendon. The use of a healed patellar tendon donor site is a viable option for revision anterior cruciate reconstructive surgery. This option prevents the possibility of disease transmission with use of an allograft. We have shown grossly and histologically that the donor site has the potential to regenerate to tissue that has the appearance of normal tendon. This option could be available for revision surgery, but would not be recommended if the initial surgery was < 18 months-2 years in the past.

Foreign bodies in the foot can remain silent for years before presentation. We describe two foreign body infections in the feet of two patients more than 18 years after the initial insult. These cases emphasize the need for careful evaluation of patients with an unexplained infection in the foot, and thorough debridement, when surgical treatment is necessary.