Design considerations for a larger inmarsat standard ship earth station

A new standard of INMARSAT ship earth station for multi-channel operation could find particular application on large passenger ships and off-shore oil/gas platforms. This paper provides estimates of platform and ship motions and discusses general design requirements, notably of the antenna system. The discussion includes consideration of possible modulation and multiple access techniques. Single channel per carrier (SCPC) operation is advocated which permits easy integration with the present service to single channel INMARSAT Standard-A ship earth stations. Major parameter/relative cost trade-off curves needed in an overall ship earth station design optimization are presented.     

Uplink adaptive depolarisation cancellation in a ground-to-satellite link

An adaptive depolarisation cancellation method to reduce the uplink depolarised signal in future satellite systems is described. It is based on transmission of a small orthogonally polarised correction signal from the earth station. A data-acquisition method using only a single beacon signal transmitted from the satellite could provide the information required for generation of the correction signal.     

Conversational comprehension processes are responsible for reasoning fallacies in children as well as adults: If is not the biconditional.

Proposes that children do poorly on reasoning from premises of the form if p then q not because they construe if as a biconditional but rather because they use discourse comprehension processes that lead them to accept the invited inferences if not p then not q and if q then p. This hypothesis predicts that children should respond appropriately to premises in which the invited inferences are countermanded. In Exp I, 24 undergraduates and 44 10-yr-olds were given conditional reasoning problems. Some of these had a major premise consisting of a single if–then sentence, while others had a more elaborate major premise in which the invited inferences were explicitly countermanded. In Exp II, Ss were 24 undergraduates, 20 10-yr-olds, and 34 7-yr-olds. In some problems the major premise consisted of a single if–then statement; in others, the major premise consisted of 3 such statements, 2 of which shared the same consequent, thus implicitly countermanding the invited inferences. In both experiments, all age groups committed the fallacies in the simple condition but not in the more complex condition. It is concluded that children's representation of if distinguishes necessary from merely invited inferences. Data suggest a collection of countermandable context-dependent inferences of varying degrees of invitingness associated with if. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Left–right memory in 2-year-old children: A new look at search tasks.

Investigated whether toddlers could remember the left and right sides of a symmetrical array. 64 22-35 mo old children learned to find a reward under 1 box of a 2- or a 9-box array. Two generalization conditions were introduced: The array was moved to new positions on 1 side of the S, or the S moved 180° to a new side of the table. To prevent visual tracking of the correct box, the array was kept covered except when the S responded. Ss were able to identify the correct side of the array after various spatial displacements; however, good performance appeared primarily for the 9-box array. Three conclusions are drawn: (a) The use of 2-choice tasks limits the study of spatial cognition; (b) a developmental shift from an egocentric to an allocentric framework may be more apparent than real; and (c) an analysis of the cognitive demands of left-right tasks provides a better basis for understanding performance than the assumption that discriminations along the horizontal axis are difficult to make and remember. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Combination chemotherapy and adriamycin in patients with advanced breast cancer. A Southwest Oncology Group study

In January, 1972, the Southwest Oncology Group initiated two randomized studies for patients with advanced breast cancer. The study for patients with prior chemotherapy showed a 33% response rate with adriamycin. The study for patients without previous chemotherapy consisted of three treatment regimens; a weekly repeated combination of cyclophosphamide, methotrexate, 5-fluorouracil, vincristine, and prednisone; these same five drugs given in courses of 5 days repeated every 4 weeks; and adriamycin as a single agent every 3 weeks. For the 283 evaluable patients, the response rates were: weekly combination 63/106 (59%); intermittent combination 39/98 (40%); and adriamycin 31/79 (39%). The median duration of response was 8 months for weekly combination, 10 months for intermittent therapy and only 4 months for adriamycin. Leukopenia was the dose-limiting toxicity with all three regimens. The weekly combination is the most effective therapy for patients with advanced disease. Extensive trails of combinations that include adriamycin are underway.     

A new slant on orientation perception.

Traditional theories of orientation perception are unable to account for orientation judgments made by young children and for certain kinds of orientation judgments made by adults (e.g., aesthetic judgments of uprightness). The present article proposes that adults process orientation information at different levels and that these levels correspond to developmental stages in the coding of orientation in childhood. Many of the apparently anomalous judgments made by children and adults can be understood as processing at an early level where the only distinction made is between upright shapes and nonupright shapes. Results of 3 experiments conducted by the author and her associates with 48 college students, 5 2-yr-olds, and 12 3-yr-olds, are presented. They offer empirical support for this view. A new interpretation is offered for some of the orientation errors observed in clinical populations and in cross-cultural studies. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Context effects in left-right shape discrimination.

The difficulty of discriminating between left–right orientations of a shape has usually been attributed to symmetrical coding in the brain or to the nature of perceptual learning. However, recent work on the context-dependent nature of the difficulty challenges such explanations and supports a more cognitive approach to the problem. The present work examined the basis for left–right difficulty in the standard two-choice task (stimuli aligned side by side) in children of 3 to 4 years. Experiment 1 found that children who learned the task with the easy, single-stimulus procedure could generalize to the difficult, two-choice task. Subsequent experiments found that the difficulty in learning the two-choice task could not be attributed to the attentional demands of the two stimuli, nor to the use of the second stimulus as a spatial referent for defining orientation. The data suggested that the standard two-choice task is difficult because it promotes the use of two competing orientation judgments. We conclude that the difficulty of left–right judgments lies in the cognitive demands of the task and is to be understood in the same terms as other problems in cognitive development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acute bleeding after bone marrow transplantation (BMT)- incidence and effect on survival. A quantitative analysis in 1,402 patients

Acute bleeding after bone marrow transplantation (BMT) was investigated in 1,402 patients receiving transplants at Johns Hopkins Hospital between January 1, 1986 and June 30, 1995. Bleeding categorization was based on daily scores of intensity used by the blood transfusion service. Moderate and severe episodes were analyzed for bleeding sites. Analysis of the cause of death and the interval of the bleeding episode to outcome endpoints was recorded. Survival estimates were computed for 1,353 BMT patients. The overall incidence was 34%. Minor bleeding was seen in 10.6%, moderate bleeding was seen in 11.3%, and severe bleeding was seen in 12% of all patients. Fourteen percent of patients had moderate or severe gastrointestinal hemorrhage, 6.4% had moderate or severe hemorrhagic cystitis, 2.8% had pulmonary hemorrhage, and 2% had intracranial hemorrhage. Sixty-one percent had 1 bleeding site and 34.4% had more than 1 site. Moderate and severe bleeding was more prevalent in allogeneic (31%) and unrelated patients (62.5%) compared with autologous patients (18.5%). Significant distribution of incidence was found among the different diagnoses, but not by disease status in acute myeloid leukemia, acute lymphoblastic leukemia, chronic myelogenous leukemia, Hodgkin's disease, and non-Hodgkin's lymphoma. Bleeding was associated with significantly reduced survival in allogeneic, autologous, and unrelated BMT and in each disease category except multiple myeloma. Survival was correlated with the bleeding intensity, bleeding site, and the number of sites. Although close temporal association was evident to mortality, bleeding was recorded as the cause of death in only the minority of cases compared with other toxicities after BMT (graft-versus-host disease, infections, and preparative regimen toxicity). Acute bleeding is a common complication after BMT that is profoundly associated with morbidity and mortality. Although bleeding was not a direct cause of death in the majority of cases, it has a potential prognostic implication as a predictor of poor outcome in clinical assessment of patients after BMT.     

Representation of depth by children: Spatial strategies and lateral biases.

Preschool and elementary-school children from the US and Israel represented depth relations in pictures. A lateral bias to place near objects on the left side appeared in English and Hebrew readers of all ages and in older Arabic readers; this bias is consistent with left–right asymmetries observed in Western art. The overall directionality of notational systems was seen as constraining, but not causing, the left bias. In all cultural groups, young children represented near–far by horizontal alignments and older children, by diagonal alignments, with virtually no vertical alignments. Front–behind representations followed a different developmental course that was interpreted as due to efforts to convey nearness between the items separated in depth. (PsycINFO Database Record (c) 2010 APA, all rights reserved)