Disk drive control: The early years

One of the persistently exciting control applications is that of disk drive servos. From the start in the early 1950s to the massive capacity commodity drives of the early 2000s, the problem of accessing data on rotating disk media has provided a wealth of control challenges to be solved. This survey paper traces the early history of disk drive control from the first disk drive in 1956 to the first commercial drive with Magneto-Resistive heads in 1990. Rather than the approach used in (Abramovitch and Franklin, 2002a) in which the histories of the components were outlined first, we will focus on the feedback loop itself in those early days. The paper will survey the different areas of the disk drive control problem and how they evolved.     

On the stability of adaptive pole-placement controllers with asaturating actuator

The authors examine how existing pole-placement algorithms work in the case of a saturating input. The stability of such algorithms and the modifications needed to make them work in the case of saturation are examined. The net result is that the analysis of G.C. Goodwin and K.S. Sin (1984) can be slightly modified to prove the stability of adaptive pole-placement, but only for the case where the plant is stable. It is shown that, for unstable plants, it is possible to push the plant into a state from which it cannot be returned to the origin (with a saturating input). Thus, it is fairly easy to generate examples of instability in the adaptive control system that would not exist with unbounded control authority     

Customizable coherent servo demodulation for disk drives

This paper describes a servo demodulator which provides greatly improved performance over the currently used servo demodulation methods for disk drives. The demodulation algorithm proposed here makes better use of knowledge about the readback signal coming from the disk to provide better noise immunity and more immunity to other nonidealities in the magnetic head response. The net result is a demodulated position error signal which has a much cleaner response     

Role of HIF-1alpha in hypoxia-mediated apoptosis, cell proliferation and tumour angiogenesis

As a result of deprivation of oxygen (hypoxia) and nutrients, the growth and viability of cells is reduced. Hypoxia-inducible factor (HIF)-1alpha helps to restore oxygen homeostasis by inducing glycolysis, erythropoiesis and angiogenesis. Here we show that hypoxia and hypoglycaemia reduce proliferation and increase apoptosis in wild-type (HIF-1alpha+/+) embryonic stem (ES) cells, but not in ES cells with inactivated HIF-1alpha genes (HIF-1alpha-/-); however, a deficiency of HIF-1alpha does not affect apoptosis induced by cytokines. We find that hypoxia/hypoglycaemia-regulated genes involved in controlling the cell cycle are either HIF-1alpha-dependent (those encoding the proteins p53, p21, Bcl-2) or HIF-1alpha-independent (p27, GADD153), suggesting that there are at least two different adaptive responses to being deprived of oxygen and nutrients. Loss of HIF-1alpha reduces hypoxia-induced expression of vascular endothelial growth factor, prevents formation of large vessels in ES-derived tumours, and impairs vascular function, resulting in hypoxic microenvironments within the tumour mass. However, growth of HIF-1alpha tumours was not retarded but was accelerated, owing to decreased hypoxia-induced apoptosis and increased stress-induced proliferation. As hypoxic stress contributes to many (patho)biological disorders, this new role for HIF-1alpha in hypoxic control of cell growth and death may be of general pathophysiological importance.     

Effect of Heat Processing on IgE Reactivity and Cross‐Reactivity of Tropomyosin and Other Allergens of Asia‐Pacific Mollusc Species: Identification of Novel Sydney Rock Oyster Tropomyosin Sac g 1

1 Scope

Shellfish allergy is an increasing global health priority, frequently affecting adults. Molluscs are an important shellfish group causing food allergy but knowledge of their allergens and cross‐reactivity is limited. Optimal diagnosis of mollusc allergy enabling accurate advice on food avoidance is difficult. Allergens of four frequently ingested Asia‐Pacific molluscs are characterized: Sydney rock oyster (Saccostrea glomerata), blue mussel (Mytilus edulis), saucer scallop (Amusium balloti), and southern calamari (Sepioteuthis australis), examining cross‐reactivity between species and with blue swimmer crab tropomyosin, Por p 1.

2 Methods and results

IgE ELISA showed that cooking increased IgE reactivity of mollusc extracts and basophil activation confirmed biologically relevant IgE reactivity. Immunoblotting demonstrated strong IgE reactivity of several proteins including one corresponding to heat‐stable tropomyosin in all species (37–40 kDa). IgE‐reactive Sydney rock oyster proteins were identified by mass spectrometry, and the novel major oyster tropomyosin allergen was cloned, sequenced, and designated Sac g 1 by the IUIS. Oyster extracts showed highest IgE cross‐reactivity with other molluscs, while mussel cross‐reactivity was weakest. Inhibition immunoblotting demonstrated high cross‐reactivity between tropomyosins of mollusc and crustacean species.

3 Conclusion

These findings inform novel approaches for reliable diagnosis and improved management of mollusc allergy.     

There are no words: Two Greek-Jewish survivors of Auschwitz.

Compares interviews with 2 Greek-Jewish survivors of Auschwitz who underwent enforced genital mutilation (unilateral orchiectomy) as part of immoral Nazi experimentation. Their contrasting reactions to the traumatic situation highlight the complex tasks of the survivor, especially the emotional difficulty of constructing a story out of the subjective experience of the Holocaust. Survivor's reactions, it is proposed, are affected by the relative identification–disidentification with their "holocaust self." Certain traumatic events, nevertheless, may remain incapable of being narrated, and clinical implications of this enforced silence are discussed in relation to the occurrence of denial, psychic numbing, survival guilt, and posttraumatic stress disorders. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Translocation inhibitors define specificity of protein kinase C isoenzymes in pancreatic beta-cells

The protein kinase C (PKC) family consists of 11 isoenzymes. Following activation, each isoenzyme translocates and binds to a specific receptor for activated C kinase (RACK) (Mochly-Rosen, D. (1995) Science 268, 247-251) that provides an anchoring site in close proximity to the isoenzyme's specific substrate. Pancreatic islet cells contain at least six PKC isoenzymes (Knutson, K. L., and Hoenig, M. (1994) Endocrinology 135, 881-886). Although PKC activation enhances insulin release, the specific function of each isoenzyme is unknown. Here we show that following stimulation with glucose, alphaPKC and epsilonPKC translocate to the cell's periphery, while deltaPKC and zetaPKC translocate to perinuclear sites. betaC2-4, a peptide derived from the RACK1-binding site in the C2 domain of betaPKC, inhibits translocation of alphaPKC and reduces insulin response to glucose. Likewise, epsilonV1-2, an epsilonPKC-derived peptide containing the site for its specific RACK, inhibits translocation of epsilonPKC and reduces insulin response to glucose. Inhibition of islet-glucose metabolism with mannoheptulose blocks translocation of both alphaPKC and epsilonPKC and diminishes insulin response to glucose while calcium-free buffer inhibits translocation of alphaPKC but not epsilonPKC and lowers insulin response by 50%. These findings illustrate the unique ability of specific translocation inhibitors to elucidate the isoenzyme-specific functions of PKC in complex signal transduction pathways.     

The effects of situation and sibling status on sibling interaction.

Observed 32 mixed-sex sibling pairs in free play in the laboratory and analyzed their interactions in terms of the sibling-status variables of age of the individual S, sex composition of the dyad, and age interval between the siblings. Younger siblings were 1.5–2.0 yrs old, and older siblings were 2.5–5.5 yrs old. Ss were observed for 4 successive 3.5-min trials. Results generally replicate those in previous home studies. As compared to their younger siblings, older siblings initiated more object struggles and, in dyads with large age intervals, they also initiated more prosocial behavior. Younger siblings imitated more often. Older females were especially prosocial. In order to study the effect of situational variables, the number of toys available and the mother's presence during the free-play observations were manipulated. There were more positive interactions with a single toy and more negative interactions with 4 toys. Finally, there were more negative interactions in mother's presence than in her absence. (French abstract) (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Budesonide versus prednisone in the treatment of active Crohn's disease. The Israeli Budesonide Study Group

BACKGROUND & AIMS: Budesonide (BUD) is a potent steroid that undergoes extensive first-pass metabolism. BUD incorporated in a pH-dependent formulation has been proposed as an alternative treatment for Crohn's disease (CD). The aim of this study was to compare the efficacy and safety of BUD and prednisone (PRED) in the treatment of active CD involving the terminal ileum and/or the colon. METHODS: Patients with mild to moderately active CD were included in a randomized, double-blind, double-dummy controlled trial. Patients received either 9 mg BUD once daily for 8 weeks or 40 mg PRED once daily for the first 2 weeks tapered gradually to 5 mg/day by the end of the study. Disease activity, quality of life, and laboratory parameters were recorded. RESULTS: One hundred patients received BUD, and 101 patients received PRED. By intention-to-treat analysis, treatment efficacy defined as Crohn's Disease Activity Index of <150 at completion was 51% and 52.5% for the BUD and PRED groups, respectively. Twice as many responded to treatment with no side effects in the BUD compared with the PRED group (30% vs. 14%) (P = 0.006). Most of the decrease in CDAI scores occurred during the first 2 weeks. CONCLUSIONS: BUD is as effective as PRED in the treatment of CD involving the terminal ileum and right colon. BUD has significantly fewer steroid-related adverse reactions.     

Children's perceptions of parental work.

249 3rd and 4th graders and both of their parents were asked about the nature of the parents' work, their attitudes toward it, and a variety of other work-related questions. The children knew in general what their parents did, where, and when. They were also somewhat aware of their parents' satisfaction with their work. Mothers who were homemakers were perceived by their children to be less satisfied with their work than were mothers in the paid labor force. However, the children were equally satisfied with the work of both groups. Children were dissatisfied with their parents' work only when their mothers worked evening or night shifts. Results are discussed in terms of the role played by parental work in the process of socialization of children regarding work. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)