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Sample records for analog som230 pasireotide

  1. The Somatostatin Analog SOM230 (Pasireotide) Ameliorates Injury of the Intestinal Mucosa and Increases Survival after Total-Body Irradiation by Inhibiting Exocrine Pancreatic Secretion

    PubMed Central

    Fu, Qiang; Berbée, Maaike; Boerma, Marjan; Wang, Junru; Schmid, Herbert A.; Hauer-Jensen, Martin

    2009-01-01

    Somatostatin analogs ameliorate intestinal injury after localized irradiation. This study investigated whether SOM230, a novel, metabolically stable analog with broad receptor affinity, reduces intestinal injury and lethality in mice exposed to total-body irradiation (TBI). Male CD2F1 mice were exposed to 7–15 Gy TBI. Twice-daily administration of SOM230 (1, 4 or 10 mg/kg per day) or vehicle was started either 2 days before or 4 h after TBI and continued for either 14 or 21 days. Parameters of intestinal and hematopoietic radiation injury, bacterial translocation, and circulating cytokine levels were assessed. Animal survival was monitored for up to 30 days. SOM230 increased survival (P < 0.001) and prolonged survival time (P < 0.001) whether administration was initiated before or after TBI. There was no benefit from administration for 21 compared to 14 days. The survival benefit of SOM230 was completely reversed by co-administration of pancreatic enzymes (P = 0.009). Consistent with the presumed non-cytoprotective mechanism of action, SOM230 did not influence hematopoietic injury or intestinal crypt lethality. However, SOM230 preserved mucosal surface area (P < 0.001) and reduced bacterial translocation in a dose-dependent manner (P < 0.001). Circulating IL-12 levels were reduced in SOM230-treated mice (P = 0.007). No toxicity from SOM230 was observed. SOM230 enhances animal survival whether administration begins before or after TBI; i.e., it is effective both as a protector and as a mitigator. The mechanism likely involves reduction of intraluminal pancreatic enzymes. Because of its efficacy and favorable safety profile, SOM230 is a promising countermeasure against radiation and should undergo further development. PMID:19580476

  2. Quantitative analysis of pasireotide (SOM230), a cyclic peptide, in monkey plasma using liquid chromatography in combination with tandem mass spectrometry.

    PubMed

    Fu, Yunlin; Li, Wenkui; Flarakos, Jimmy; Tse, Francis L S

    2016-01-01

    A novel liquid chromatographic method with tandem mass spectrometric detection (LC-MS/MS) for the determination of Pasireotide (SOM230) was developed and validated with a dynamic range of 0.5-250ng/ml using 50μl of monkey plasma. SOM230 and the internal standard, [M+6]SOM230, were extracted from monkey plasma via μElution SPE. The acidified sample matrix was loaded onto the preconditioned Waters SPE plate for further processing. The analyte was eluted from the SPE plate using freshly prepared elution solvent, which was followed by dilution and LC-MS/MS analysis. By eliminating a step of evaporation of the SPE eluent, instead, injecting the eluent after a simple dilution, compound loss due to non-specific binding to the 96-well materials was prevented. Furthermore, freshly prepared elution solution was found a key to optimal extraction recovery of the analyte from monkey plasma. The optimal chromatographic separation was achieved on an Atlantis dC18 (50×2.1mm, 5μm particle size) column using gradient elution with a total analysis cycle time approximately 4min per injection. The mobile phases were water containing 0.5% acetic acid and 0.05% trifluoroacetic acid (TFA) (mobile phase A) and acetonitrile containing 0.5% acetic acid and 0.05% TFA (mobile phase B). The incorporation of TFA (0.05%, v/v) and acetic acid (0.5%, v/v) into the mobile phases was accompanied by the improved chromatography and minimized carryover due to the HPLC column. The current method was validated for specificity, sensitivity, matrix effect, recovery, linearity, accuracy and precision, dilution integrity, batch size and stability. The accuracy and precision for the LLOQs (0.5ng/ml) were within ±5.6% bias and ≤7.8% CV, respectively. From the intra-day and inter-day evaluations, the precision of the other QC samples (1.5, 7.5, 75 and 190ng/ml) ranged from 2.7 to 4.9% CV and the accuracy (% bias) from -1.3 to 7.3%, respectively. Additional assessment of incurred sample reanalysis (ISR

  3. Osilodrostat (LCI699), a potent 11β-hydroxylase inhibitor, administered in combination with the multireceptor-targeted somatostatin analog pasireotide: A 13-week study in rats

    SciTech Connect

    Li, Li; Vashisht, Kapil; Boisclair, Julie; Li, Wenkui; Lin, Tsu-han; Schmid, Herbert A.; Kluwe, William; Schoenfeld, Heidi; Hoffmann, Peter

    2015-08-01

    The somatostatin analog pasireotide and the 11β-hydroxylase inhibitor osilodrostat (LCI699) reduce cortisol levels by distinct mechanisms of action. There exists a scientific rationale to investigate the clinical efficacy of these two agents in combination. This manuscript reports the results of a toxicology study in rats, evaluating different doses of osilodrostat and pasireotide alone and in combination. Sixty male and 60 female rats were randomized into single-sex groups to receive daily doses of pasireotide (0.3 mg/kg/day, subcutaneously), osilodrostat (20 mg/kg/day, orally), osilodrostat/pasireotide in combination (low dose, 1.5/0.03 mg/kg/day; mid-dose, 5/0.1 mg/kg/day; or high dose, 20/0.3 mg/kg/day), or vehicle for 13 weeks. Mean body-weight gains from baseline to Week 13 were significantly lower in the pasireotide-alone and combined-treatment groups compared to controls, and were significantly higher in female rats receiving osilodrostat monotherapy. Osilodrostat and pasireotide monotherapies were associated with significant changes in the histology and mean weights of the pituitary and adrenal glands, liver, and ovary/oviduct. Osilodrostat alone was associated with adrenocortical hypertrophy and hepatocellular hypertrophy. In combination, osilodrostat/pasireotide did not exacerbate any target organ changes and ameliorated the liver and adrenal gland changes observed with monotherapy. C{sub max} and AUC{sub 0–24h} of osilodrostat and pasireotide increased in an approximately dose-proportional manner. In conclusion, the pasireotide and osilodrostat combination did not exacerbate changes in target organ weight or toxicity compared with either monotherapy, and had an acceptable safety profile; addition of pasireotide to the osilodrostat regimen may attenuate potential adrenal gland hyperactivation and hepatocellular hypertrophy, which are potential side effects of osilodrostat monotherapy. - Highlights: • We examined the target organ toxicity of SOM230

  4. Pasireotide in Acromegaly: A Review.

    PubMed

    McKeage, Kate

    2015-06-01

    Pasireotide (Signifor(®), Signifor(®) LAR) is a somatostatin analogue recently approved for the treatment of acromegaly. Unlike the first-generation agents, octreotide and lanreotide, which bind preferentially to somatostatin receptor (SSTR)-2, pasireotide binds to multiple SSTRs. This article reviews the clinical use and summarizes the pharmacological properties of intramuscular pasireotide in the treatment of acromegaly. The efficacy of pasireotide 40 mg every 28 days was superior to that of intramuscular octreotide 20 mg every 28 days with regard to biochemical control in a 12-month, phase III trial in medically naive patients. Similarly, in a 6-month, phase III trial in patients with acromegaly inadequately controlled with somatostatin analogues for at least 6 months, the efficacy of pasireotide 40 or 60 mg was superior to that of continued octreotide 30 mg or lanreotide autogel 120 mg (each drug was administered once every 28 days) with regard to biochemical control. The tolerability profile of intramuscular pasireotide is generally similar to that of first-generation agents, except for a higher incidence of hyperglycaemia-related adverse events with pasireotide. In clinical trials, the risk of developing pasireotide-associated hyperglycaemia was numerically greater in patients categorized as diabetic or prediabetic at baseline than in those with normal glucose tolerance. Careful monitoring of glycaemic status is required prior to and during pasireotide treatment and antidiabetic therapy should be commenced as indicated. Thus, in the treatment of acromegaly, pasireotide may be a more effective somatostatin analogue than other approved agents of the same class; however, the increased risk of hyperglycaemia needs to be considered and proactively managed. PMID:26017304

  5. Phase II clinical trial of pasireotide long-acting repeatable in patients with metastatic neuroendocrine tumors

    PubMed Central

    Cives, M; Kunz, P L; Morse, B; Coppola, D; Schell, M J; Campos, T; Nguyen, P T; Nandoskar, P; Khandelwal, V; Strosberg, J R

    2015-01-01

    Pasireotide long-acting repeatable (LAR) is a novel somatostatin analog (SSA) with avid binding affinity to somatostatin receptor subtypes 1, 2, 3 (SSTR1,2,3) and 5 (SSTR5). Results from preclinical studies indicate that pasireotide can inhibit neuroendocrine tumor (NET) growth more robustly than octreotide in vitro. This open-label, phase II study assessed the clinical activity of pasireotide in treatment-naïve patients with metastatic grade 1 or 2 NETs. Patients with metastatic pancreatic and extra-pancreatic NETs were treated with pasireotide LAR (60 mg every 4 weeks). Previous systemic therapy, including octreotide and lanreotide, was not permitted. Tumor assessments were performed every 3 months using Response Evaluation Criteria in Solid Tumors (RECIST) criteria. The primary endpoint was progression-free survival (PFS). The secondary endpoints included overall survival (OS), overall radiographic response rate (ORR), and safety. Twenty-nine patients were treated with pasireotide LAR (60 mg every 4 weeks) and 28 were evaluable for response. The median PFS was 11 months. The most favorable effect was observed in patients with low hepatic tumor burden, normal baseline chromogranin A, and high tumoral SSTR5 expression. Median OS has not been reached; the 30-month OS rate was 70%. The best radiographic response was partial response in one patient (4%), stable disease in 17 patients (60%), and progressive disease in ten patients (36%). Although grade 3/4 toxicities were rare, pasireotide LAR treatment was associated with a 79% rate of hyperglycemia including 14% grade 3 hyperglycemia. Although pasireotide appears to be an effective antiproliferative agent in the treatment of advanced NETs, the high incidence of hyperglycemia raises concerns regarding its suitability as a first-line systemic agent in unselected patients. SSTR5 expression is a potentially predictive biomarker for response. PMID:25376618

  6. Serial follow-up of presurgical treatment using pasireotide long-acting release with or without octreotide long-acting release for naïve active acromegaly.

    PubMed

    Chang, Jan-Shun; Tseng, Ham-Min; Chang, Tien-Chun

    2016-06-01

    The aim of the present study was to evaluate the serial changes of GH and IGF-1 in seven patients with naïve, active acromegaly following presurgical treatment of the somatostatin analog pasireotide long-acting release (LAR) and octreotide LAR. The patients were treated with pasireotide LAR with or without octreotide LAR for two years and underwent transsphenoidal adenomectomy. After treatment with the somatostatin analogs, the surgical cure rate was similar to that in patients who underwent transsphenoidal surgery alone. Diabetes insipidus was not identified in any patients after the operation. Pasireotide LAR was effective on GH as well as IGF-1 suppression and tumor size decreasing when used as the primary therapy. Future large-population studies to investigate the surgical curative rate after presurgical treatment with somatostatin analogs in patients with acromegaly and macroadenomas close to the cavernous sinus are warranted. However, that hyperglycemia developed following pre-surgical treatment with pasireotide should take into consideration. PMID:27117887

  7. Pasireotide Therapy of Multiple Endocrine Neoplasia Type 1–Associated Neuroendocrine Tumors in Female Mice Deleted for an Men1 Allele Improves Survival and Reduces Tumor Progression

    PubMed Central

    Walls, Gerard V.; Stevenson, Mark; Soukup, Benjamin S.; Lines, Kate E.; Grossman, Ashley B.; Schmid, Herbert A.

    2016-01-01

    Pasireotide, a somatostatin analog, is reported to have anti-proliferative effects in neuroendocrine tumors (NETs). We therefore assessed the efficacy of pasireotide for treating pancreatic and pituitary NETs that develop in a mouse model of multiple endocrine neoplasia type 1 (MEN1). Men1+/− mice were treated from age 12 mo with 40 mg/kg pasireotide long-acting release formulation, or PBS, intramuscularly monthly for 9 mo. The Men1+/− mice had magnetic resonance imaging at 12 and 21 mo, and from 20 mo oral 5-bromo-2-deoxyuridine for 1 mo, to assess tumor development and proliferation, respectively. NETs were collected at age 21 mo, and proliferation and apoptosis assessed by immunohistochemistry and TUNEL assays, respectively. Pasireotide-treated Men1+/− mice had increased survival (pasireotide, 80.9% vs PBS, 65.2%; P < .05), with fewer mice developing pancreatic NETs (pasireotide, 86.9% vs PBS, 96.9%; P < .05) and smaller increases in pituitary NET volumes (pre-treated vs post-treated, 0.803 ± 0.058 mm3 vs 2.872 ± 0.728 mm3 [pasireotide] compared with 0.844 ± 0.066 mm3 vs 8.847 ±1.948 mm3 [PBS]; P < .01). In addition, pasireotide-treated mice had fewer pancreatic NETs compared with PBS-treated mice (2.36 ± 0.25 vs 3.72 ± 0.32, respectively; P < .001), with decreased proliferation in pancreatic NETs (pasireotide, 0.35 ± 0.03% vs PBS, 0.78 ± 0.08%; P < .0001) and pituitary NETs (pasireotide, 0.73 ±0.07% vs PBS, 1.81 ± 0.15%; P < .0001), but increased apoptosis in pancreatic NETs (pasireotide, 0.42 ± 0.05% vs PBS, 0.19 ± 0.03%; P < .001) and pituitary NETs (pasireotide, 14.75 ± 1.58% vs PBS, 2.35 ± 0.44%; P < .001). Thus, pasireotide increased survival and inhibited pancreatic and pituitary NET growth, thereby indicating its potential as an anti-proliferative and pro-apoptotic therapy. PMID:26990064

  8. Pasireotide Therapy of Multiple Endocrine Neoplasia Type 1-Associated Neuroendocrine Tumors in Female Mice Deleted for an Men1 Allele Improves Survival and Reduces Tumor Progression.

    PubMed

    Walls, Gerard V; Stevenson, Mark; Soukup, Benjamin S; Lines, Kate E; Grossman, Ashley B; Schmid, Herbert A; Thakker, Rajesh V

    2016-05-01

    Pasireotide, a somatostatin analog, is reported to have anti-proliferative effects in neuroendocrine tumors (NETs). We therefore assessed the efficacy of pasireotide for treating pancreatic and pituitary NETs that develop in a mouse model of multiple endocrine neoplasia type 1 (MEN1). Men1(+/-) mice were treated from age 12 mo with 40 mg/kg pasireotide long-acting release formulation, or PBS, intramuscularly monthly for 9 mo. The Men1(+/-) mice had magnetic resonance imaging at 12 and 21 mo, and from 20 mo oral 5-bromo-2-deoxyuridine for 1 mo, to assess tumor development and proliferation, respectively. NETs were collected at age 21 mo, and proliferation and apoptosis assessed by immunohistochemistry and TUNEL assays, respectively. Pasireotide-treated Men1(+/-) mice had increased survival (pasireotide, 80.9% vs PBS, 65.2%; P < .05), with fewer mice developing pancreatic NETs (pasireotide, 86.9% vs PBS, 96.9%; P < .05) and smaller increases in pituitary NET volumes (pre-treated vs post-treated, 0.803 ± 0.058 mm(3) vs 2.872 ± 0.728 mm(3) [pasireotide] compared with 0.844 ± 0.066 mm(3) vs 8.847 ±1.948 mm(3) [PBS]; P < .01). In addition, pasireotide-treated mice had fewer pancreatic NETs compared with PBS-treated mice (2.36 ± 0.25 vs 3.72 ± 0.32, respectively; P < .001), with decreased proliferation in pancreatic NETs (pasireotide, 0.35 ± 0.03% vs PBS, 0.78 ± 0.08%; P < .0001) and pituitary NETs (pasireotide, 0.73 ±0.07% vs PBS, 1.81 ± 0.15%; P < .0001), but increased apoptosis in pancreatic NETs (pasireotide, 0.42 ± 0.05% vs PBS, 0.19 ± 0.03%; P < .001) and pituitary NETs (pasireotide, 14.75 ± 1.58% vs PBS, 2.35 ± 0.44%; P < .001). Thus, pasireotide increased survival and inhibited pancreatic and pituitary NET growth, thereby indicating its potential as an anti-proliferative and pro-apoptotic therapy. PMID:26990064

  9. Clinical use of pasireotide for Cushing’s disease in adults

    PubMed Central

    Ceccato, Filippo; Scaroni, Carla; Boscaro, Marco

    2015-01-01

    Cushing’s disease Excessive corticotroph hormone levels sustained by an adrenocorticotropic hormone-secreting pituitary adenoma lead to a severe clinical condition caused by excess cortisol secretion, called Cushing’s disease (CD). Neurosurgery and radiotherapy are used to treat the pituitary adenoma directly, but new medical treatments targeting the corticotroph cells have recently become available. Pasireotide This is a novel multireceptor ligand somatostatin (SST) analog with a high binding affinity for SST receptor 5, the predominant receptor in human corticotroph adenomas that is not downregulated by high cortisol levels (as SST receptor 2 is). Pasireotide has been recently approved by the European Medical Agency and the US Food and Drug Administration for treating adults with CD with recurrent hypercortisolism after surgery, or for whom surgery is not an option. A dose of 600–1,200 μg twice a day can normalize urinary free cortisol levels after 3 months of treatment in up to 28% of patients, reducing their blood pressure and improving their weight, lipid profile, and quality of life. Combining pasireotide with cabergoline to achieve a greater hormone response can normalize cortisol secretion in 50% of patients, and adding ketoconazole induces biochemical control in most patients with CD. Safety and hyperglycemia The adverse effects of pasireotide are similar to those of other SST analogs, including diarrhea, nausea, and biliary sludge or gallstones. Hyperglycemia is common during pasireotide treatment, which affects the secretion of pancreatic insulin and intestinal glucagon-like peptide 1. Self-monitoring is essential to achieve good metabolic control, and endocrinologists should first administer metformin if insulin resistance is evident and then add dipeptidyl peptidase 4 inhibitors/glucagon-like peptide 1 receptor agonists or insulin. Conclusion In recent years, medical treatment with pasireotide has been proposed as monotherapy for adults with CD

  10. Pasireotide and octreotide antiproliferative effects and sst2 trafficking in human pancreatic neuroendocrine tumor cultures.

    PubMed

    Mohamed, Amira; Blanchard, Marie-Pierre; Albertelli, Manuela; Barbieri, Federica; Brue, Thierry; Niccoli, Patricia; Delpero, Jean-Robert; Monges, Genevieve; Garcia, Stephane; Ferone, Diego; Florio, Tullio; Enjalbert, Alain; Moutardier, Vincent; Schonbrunn, Agnes; Gerard, Corinne; Barlier, Anne; Saveanu, Alexandru

    2014-10-01

    Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) raise difficult therapeutic problems despite the emergence of targeted therapies. Somatostatin analogs (SSA) remain pivotal therapeutic drugs. However, the tachyphylaxis and the limited antitumoral effects observed with the classical somatostatin 2 (sst2) agonists (octreotide and lanreotide) led to the development of new SSA, such as the pan sst receptor agonist pasireotide. Our aim was to compare the effects of pasireotide and octreotide on cell survival, chromogranin A (CgA) secretion, and sst2 phosphorylation/trafficking in pancreatic NET (pNET) primary cells from 15 tumors. We established and characterized the primary cultures of human pancreatic tumors (pNETs) as powerful preclinical models for understanding the biological effects of SSA. At clinically relevant concentrations (1-10 nM), pasireotide was at least as efficient as octreotide in inhibiting CgA secretion and cell viability through caspase-dependent apoptosis during short treatments, irrespective of the expression levels of the different sst receptors or the WHO grade of the parental tumor. Interestingly, unlike octreotide, which induces a rapid and persistent partial internalization of sst2 associated with its phosphorylation on Ser341/343, pasireotide did not phosphorylate sst2 and induced a rapid and transient internalization of the receptor followed by a persistent recycling at the cell surface. These results provide the first evidence, to our knowledge, of striking differences in the dynamics of sst2 trafficking in pNET cells treated with the two SSAs, but with similar efficiency in the control of CgA secretion and cell viability. PMID:25012983

  11. Successful Medical Treatment of Adult Nesidioblastosis With Pasireotide over 3 Years

    PubMed Central

    Schwetz, Verena; Horvath, Karl; Kump, Patrizia; Lackner, Carolin; Perren, Aurel; Forrer, Flavio; Pieber, Thomas R.; Treiber, Gerlies; Sourij, Harald; Mader, Julia K.

    2016-01-01

    Abstract Nesidioblastosis is a rare cause of endogenous hyperinsulinemic hypoglycemia in adults. Diagnosis is often challenging and therapeutic options are scarce. In 2009, a 46-year-old female patient presented with recurrent severe hypoglycemia and immediate recovery after glucose ingestion. Although 72-h-fasting test was positive, various imaging technologies (sonography, computed tomography, somatostatin receptor scintigraphy, dopamine receptor positron emission tomography [DOPA-PET]) were negative. Endoscopic ultrasound revealed a lesion in the pancreatic corpus, whereas selective arterial calcium stimulation test, portal venous sampling and GLP-1-receptor scintigraphy were indicative of a lesion in the pancreatic tail, which was surgically removed. The histopathologic examination revealed beta cell hyperplasia and microadenomas expressing glucagon. After surgery, the patient was free of symptoms for 6 months, after which hypoglycemic episodes recurred. After unsuccessful treatment with corticosteroids and somatostatin analogs, treatment with pasireotide, a novel somatostatin analog with high affinity to somatostatin receptor 5 and a possible side effect of hyperglycemia, was initiated (0.6 mg BID). To date, our patient has been free of severe hypoglycemic episodes ever since. Yearly repeated imaging procedures have shown no abnormities over the last 3 years. We report for the first time that pasireotide was successfully used in the treatment of adult nesidioblastosis. PMID:27057885

  12. Pasireotide: a novel treatment for patients with acromegaly.

    PubMed

    Cuevas-Ramos, Daniel; Fleseriu, Maria

    2016-01-01

    Morbidity and mortality rates in patients with active acromegaly are higher than the general population. Adequate biochemical control restores mortality to normal rates. Now, medical therapy has an increasingly important role in the treatment of patients with acromegaly. Somatostatin receptor ligands (SRLs) are considered the standard medical therapy, either after surgery or as a first-line therapy when surgery is deemed ineffective or is contraindicated. Overall, octreotide and lanreotide are first-generation SRLs and are effective in ~20%-70% of patients. Pegvisomant, a growth hormone receptor antagonist, controls insulin-like growth factor 1 in 65%-90% of cases. Consequently, a subset of patients (nonresponders) requires other treatment options. Drug combination therapy offers the potential for more efficacious disease control. However, the development of new medical therapies remains essential. Here, emphasis is placed on new medical therapies to control acromegaly. There is a focus on pasireotide long-acting release (LAR) (Signifor LAR®), which was approved in 2014 by the US Food and Drug Administration and the European Medicine Agency for the treatment of acromegaly. Pasireotide LAR is a long-acting somatostatin multireceptor ligand. In a Phase III clinical trial in patients with acromegaly (naïve to medical therapy or uncontrolled on a maximum dose of first-generation SRLs), 40 and 60 mg of intramuscular pasireotide LAR achieved better biochemical disease control than octreotide LAR, and tumor shrinkage was noted in both pasireotide groups. Pasireotide LAR tolerability was similar to other SRLs, except for a greater frequency and degree of hyperglycemia and diabetes mellitus. Baseline glucose may predict hyperglycemia occurrence after treatment, and careful monitoring of glycemic status and appropriate treatment is required. A precise definition of patients with acromegaly who will derive the greatest therapeutic benefit from pasireotide LAR remains to be

  13. Pasireotide: a novel treatment for patients with acromegaly

    PubMed Central

    Cuevas-Ramos, Daniel; Fleseriu, Maria

    2016-01-01

    Morbidity and mortality rates in patients with active acromegaly are higher than the general population. Adequate biochemical control restores mortality to normal rates. Now, medical therapy has an increasingly important role in the treatment of patients with acromegaly. Somatostatin receptor ligands (SRLs) are considered the standard medical therapy, either after surgery or as a first-line therapy when surgery is deemed ineffective or is contraindicated. Overall, octreotide and lanreotide are first-generation SRLs and are effective in ~20%–70% of patients. Pegvisomant, a growth hormone receptor antagonist, controls insulin-like growth factor 1 in 65%–90% of cases. Consequently, a subset of patients (nonresponders) requires other treatment options. Drug combination therapy offers the potential for more efficacious disease control. However, the development of new medical therapies remains essential. Here, emphasis is placed on new medical therapies to control acromegaly. There is a focus on pasireotide long-acting release (LAR) (Signifor LAR®), which was approved in 2014 by the US Food and Drug Administration and the European Medicine Agency for the treatment of acromegaly. Pasireotide LAR is a long-acting somatostatin multireceptor ligand. In a Phase III clinical trial in patients with acromegaly (naïve to medical therapy or uncontrolled on a maximum dose of first-generation SRLs), 40 and 60 mg of intramuscular pasireotide LAR achieved better biochemical disease control than octreotide LAR, and tumor shrinkage was noted in both pasireotide groups. Pasireotide LAR tolerability was similar to other SRLs, except for a greater frequency and degree of hyperglycemia and diabetes mellitus. Baseline glucose may predict hyperglycemia occurrence after treatment, and careful monitoring of glycemic status and appropriate treatment is required. A precise definition of patients with acromegaly who will derive the greatest therapeutic benefit from pasireotide LAR remains to

  14. Effectiveness of low-dose pasireotide in a patient with Cushing’s disease: antiproliferative effect and predictivity of a short pasireotide suppression test

    PubMed Central

    Grossrubatscher, Erika; Zampetti, Benedetta; Dalino Ciaramella, Paolo; Doneda, Paola; Loli, Paola

    2015-01-01

    Key Clinical Message This case shows efficacy of low-dose pasireotide in biochemical and clinical control of severe hypercortisolism and in tumor volume reduction in a patient with an ACTH-secreting macroadenoma. The drug may be an option for long-term treatment in some patients where control of tumor mass is an important clinical endpoint. PMID:26331021

  15. Effectiveness of low-dose pasireotide in a patient with Cushing's disease: antiproliferative effect and predictivity of a short pasireotide suppression test.

    PubMed

    Grossrubatscher, Erika; Zampetti, Benedetta; Dalino Ciaramella, Paolo; Doneda, Paola; Loli, Paola

    2015-08-01

    This case shows efficacy of low-dose pasireotide in biochemical and clinical control of severe hypercortisolism and in tumor volume reduction in a patient with an ACTH-secreting macroadenoma. The drug may be an option for long-term treatment in some patients where control of tumor mass is an important clinical endpoint. PMID:26331021

  16. Evaluation of the Effects of Pasireotide LAR Administration on Lymphocele Prevention after Axillary Node Dissection for Breast Cancer: Results of a Randomized Non-Comparative Phase 2 Study

    PubMed Central

    Chéreau, Elisabeth; Uzan, Catherine; Boutmy-Deslandes, Emmanuelle; Zohar, Sarah; Bézu, Corinne; Mazouni, Chafika; Garbay, Jean-Rémi; Daraï, Emile; Rouzier, Roman

    2016-01-01

    Objective The aim of this study was to assess the efficacy (response rate centered on 80%) of a somatostatin analog with high affinity for 4 somatostatin receptors in reducing the postoperative incidence of symptomatic lymphocele formation following total mastectomy with axillary lymph node dissection. Setting This prospective, double-blind, randomised, placebo-controlled, phase 2 trial was conducted in two secondary care centres. Participants All female patients for whom mastectomy and axillary lymph node dissection were indicated were eligible for the study, including patients who had received neo-adjuvant chemotherapy. Main exclusion criteria were related to diabetes, cardiac insufficiency, disorder of cardiac conduction or hepatic failure. Interventions Patients were randomised to receive one injection of either prolonged-release pasireotide 60 mg or placebo (physiological serum), which were administered intramuscularly 7 to 10 days before the scheduled surgery. The study was conducted in a double-blind manner. Primary and Secondary Outcome Measures The primary outcome measure was the percentage of patients who did not develop post-operative axillary symptomatic lymphoceles during the 2 postoperative months. Secondary endpoints were the total quantity of lymph drained, duration and daily volume of drainage and aspirated volumes of lymph. Results Ninety-one patients were randomised. Ninety patients were evaluable: 42 patients received pasireotide, and 48 patients received placebo. The mean estimated response rate were 62.4% (95% Credibility Interval [CrI]: 48.6%-75.3%) in the treatment group and 50.2% (95% CrI: 37.6%-62.8%) in the placebo group. Overall safety was comparable across groups, and one serious adverse event occurred. In the treatment group, one patient with known insulin-depe*ndent diabetes required hospitalization for hyperglycaemia. Conclusions With this phase 2 preliminary study, even if our results indicate a trend towards a reduction in

  17. Effect of pasireotide on glucose- and growth hormone-related biomarkers in patients with inadequately controlled acromegaly.

    PubMed

    Schmid, Herbert A; Brue, Thierry; Colao, Annamaria; Gadelha, Mônica R; Shimon, Ilan; Kapur, Karen; Pedroncelli, Alberto M; Fleseriu, Maria

    2016-07-01

    The purpose of this study was to gain more insight into the mechanism of action of pasireotide in patients who completed the PAOLA study. PAOLA was a 24-week, Phase III, randomized, three-arm study of pasireotide LAR 40 and 60 mg versus octreotide LAR 30 mg or lanreotide Autogel 120 mg in patients with inadequately controlled acromegaly. The current work was a planned exploratory objective of the PAOLA study that evaluated changes in levels of growth hormone (GH), insulin-like growth factor 1 (IGF-1), IGF-binding proteins (IGFBP-2, IGFBP-3), glycated haemoglobin (HbA1c) and fasting plasma glucose (FPG) in each treatment arm. Responders to pasireotide LAR (mean GH levels <2.5 μg/L and normal IGF-1 levels at 24 weeks) had lower GH and IGF-1 levels at baseline (GH 5.1 ng/mL, IGF-1 519 ng/mL) than non-responders (GH 7.9 ng/mL, IGF-1 672 ng/mL). Frequency of hyperglycaemia after pasireotide treatment was similar in responders and non-responders and depended more on the baseline FPG level. 47 % of all patients treated with pasireotide LAR (40 or 60 mg) did not receive antidiabetic medication at any time during this study. This is the first study to evaluate the treatment effect of pasireotide on key hormonal and glycaemic biomarkers and to identify potential predictors of pasireotide-associated hyperglycaemia. Pre-treatment glucose status may be predictive of the development of pasireotide-associated hyperglycaemia. A large subset of patients with acromegaly does not experience major disturbances in glucose homeostasis while receiving pasireotide LAR. PMID:26906713

  18. From bulk to plasmonic nanoparticle surfaces: the behavior of two potent therapeutic peptides, octreotide and pasireotide.

    PubMed

    Hernández, Belén; López-Tobar, Eduardo; Sanchez-Cortes, Santiago; Coïc, Yves-Marie; Baron, Bruno; Chenal, Alexandre; Kruglik, Sergei G; Pflüger, Fernando; Cohen, Régis; Ghomi, Mahmoud

    2016-09-21

    Octreotide and pasireotide are two cyclic somatostatin analogues with an important clinical use in the treatment and diagnosis of neuroendocrine tumors. Herein, by the combined use of several techniques (UV-visible absorption, fluorescence, circular dichroism, ζ-potential, transmission electron microscopy, Raman scattering, surface-enhanced Raman scattering, and quantum mechanical calculations) we have followed the structural dynamics of these analogues in the bulk, as well as their binding sites on plasmonic (gold and silver) colloids. In contrast to the previously derived conclusions, the two peptides seem to possess completely different conformational features. Octreotide, a cyclic octapeptide, is formed by a moderately flexible type-II'β-turn maintained by a deformable disulfide linkage. Pasireotide, in which the cyclic character is made possible by peptide bonds, manifests a rigid backbone formed by two oppositely placed tight turns of different types, i.e.γ-turn and type-I β-turn. Owing to their cationic character, both analogues induce aggregation of negatively charged gold and silver colloids. Nevertheless, despite their notable structural differences, both peptides bind onto gold nanoparticles through their unique d-Trp residue. In contrast, their binding to silver colloids seems to be of electrostatic nature, as formed through monodentate or bidentate ionic pairs. PMID:27537101

  19. Phase III study of pasireotide long-acting release in patients with metastatic neuroendocrine tumors and carcinoid symptoms refractory to available somatostatin analogues

    PubMed Central

    Wolin, Edward M; Jarzab, Barbara; Eriksson, Barbro; Walter, Thomas; Toumpanakis, Christos; Morse, Michael A; Tomassetti, Paola; Weber, Matthias M; Fogelman, David R; Ramage, John; Poon, Donald; Gadbaw, Brian; Li, Jiang; Pasieka, Janice L; Mahamat, Abakar; Swahn, Fredrik; Newell-Price, John; Mansoor, Wasat; Öberg, Kjell

    2015-01-01

    In a randomized, double-blind, Phase III study, we compared pasireotide long-acting release (pasireotide LAR) with octreotide long-acting repeatable (octreotide LAR) in managing carcinoid symptoms refractory to first-generation somatostatin analogues. Adults with carcinoid tumors of the digestive tract were randomly assigned (1:1) to receive pasireotide LAR (60 mg) or octreotide LAR (40 mg) every 28 days. Primary outcome was symptom control based on frequency of bowel movements and flushing episodes. Objective tumor response was a secondary outcome. Progression-free survival (PFS) was calculated in a post hoc analysis. Adverse events were recorded. At the time of a planned interim analysis, the data monitoring committee recommended halting the study because of a low predictive probability of showing superiority of pasireotide over octreotide for symptom control (n=43 pasireotide LAR, 20.9%; n=45 octreotide LAR, 26.7%; odds ratio, 0.73; 95% confidence interval [CI], 0.27–1.97; P=0.53). Tumor control rate at month 6 was 62.7% with pasireotide and 46.2% with octreotide (odds ratio, 1.96; 95% CI, 0.89–4.32; P=0.09). Median (95% CI) PFS was 11.8 months (11.0 – not reached) with pasireotide versus 6.8 months (5.6 – not reached) with octreotide (hazard ratio, 0.46; 95% CI, 0.20–0.98; P=0.045). The most frequent drug-related adverse events (pasireotide vs octreotide) included hyperglycemia (28.3% vs 5.3%), fatigue (11.3% vs 3.5%), and nausea (9.4% vs 0%). We conclude that, among patients with carcinoid symptoms refractory to available somatostatin analogues, similar proportions of patients receiving pasireotide LAR or octreotide LAR achieved symptom control at month 6. Pasireotide LAR showed a trend toward higher tumor control rate at month 6, although it was statistically not significant, and was associated with a longer PFS than octreotide LAR. PMID:26366058

  20. Clinical management of critically ill patients with Cushing's disease due to ACTH-secreting pituitary macroadenomas: effectiveness of presurgical treatment with pasireotide.

    PubMed

    Cannavo, S; Messina, E; Albani, A; Ferrau, F; Barresi, V; Priola, S; Esposito, F; Angileri, F

    2016-06-01

    The management of critically ill Cushing's disease (CD) patients is extremely challenging. Pasireotide is indicated for the treatment of CD patients when pituitary surgery is unfeasible or has not been curative, but no data are available about the use of this drug as pre-operative treatment in critically ill patients. We report the effects of presurgical pasireotide therapy in CD patients in whom hypercortisolism caused life-threatening hypokalemia, alkalosis, and cardio-respiratory complications precluding surgical approach. Clinical, biochemical, and radiological data of two critically ill patients with ACTH-secreting pituitary macroadenoma, before and during first-line presurgical pasireotide treatment (600 μg s.c. bid). During the first 21 days of treatment, pasireotide therapy induced a rapid, partial decrease of plasma ACTH, serum cortisol, and urinary free cortisol levels, with the consequent normalization of serum potassium concentration and arterial blood gases parameters, in both the patients. They did not experience unmanageable side effects and underwent endoscopic transsphenoidal surgery after 4 weeks of effective treatment. Pre-operative MRI evaluation did not show pituitary tumor shrinkage. Surgical cure of CD was obtained in the first patient, while debulking allowed the pharmacological control of hypercortisolism in the second case. We suggest that pasireotide can induce a rapid improvement of clinical and metabolic conditions in critically ill CD patients in whom surgical approach is considered hazardous and need to be delayed. PMID:25877016

  1. A phase 2 trial of everolimus and pasireotide long-acting release in patients with metastatic uveal melanoma.

    PubMed

    Shoushtari, Alexander N; Ong, Leonard T; Schoder, Heiko; Singh-Kandah, Shahnaz; Abbate, Kelly T; Postow, Michael A; Callahan, Margaret K; Wolchok, Jedd; Chapman, Paul B; Panageas, Katherine S; Schwartz, Gary K; Carvajal, Richard D

    2016-06-01

    The aim of this study was to test the hypothesis that inhibiting mammalian target of rapamycin and insulin-like growth factor-1 receptor would be efficacious in metastatic uveal melanoma. This was a phase 2 trial of everolimus 10 mg daily plus pasireotide long-acting release 60 mg every 28 days enrolling patients with progressive, metastatic uveal melanoma to treatment until progression by Response Evaluation Criteria In Solid Tumors 1.1 (RECIST 1.1) or unacceptable toxicity. The primary endpoint was clinical benefit rate, defined as any objective response or RECIST 1.1 stable disease at 16 weeks. A subset of patients underwent baseline indium-111-octreotide scans. A total of 14 patients were enrolled, of which 13 were evaluable for the primary endpoint, before the study was terminated due to poor accrual. Three of 13 (26%) patients obtained clinical benefit. Seven of 13 (54%) had stable disease lasting for a median of 8 weeks (range: 8-16 weeks). Grade 3 adverse events deemed at least possibly related to study drugs were hyperglycemia (n=7), oral mucositis (n=2), diarrhea (n=1), hypophosphatemia (n=1), and anemia (n=1). Seven of 14 (50%) patients required at least one dose reduction due to toxicity. Seven of eight (88%) patients with baseline indium-111-octreotide scans had at least one avid lesion, with significant intrapatient heterogeneity. There was a trend toward an association between octreotide avidity and cytostatic response to therapy (P=0.078). The combination of everolimus and pasireotide has limited clinical benefit in this small metastatic uveal melanoma cohort. Dose reductions for side effects were common. Further investigation into the relationship between somatostatin receptor expression and cytostatic activity of somatostatin analogues is warranted. PMID:26795274

  2. Lunar Analog

    NASA Technical Reports Server (NTRS)

    Cromwell, Ronita L.

    2009-01-01

    In this viewgraph presentation, a ground-based lunar analog is developed for the return of manned space flight to the Moon. The contents include: 1) Digital Astronaut; 2) Bed Design; 3) Lunar Analog Feasibility Study; 4) Preliminary Data; 5) Pre-pilot Study; 6) Selection of Stockings; 7) Lunar Analog Pilot Study; 8) Bed Design for Lunar Analog Pilot.

  3. The expanding role of somatostatin analogs in gastroenteropancreatic and lung neuroendocrine tumors.

    PubMed

    Cives, Mauro; Strosberg, Jonathan

    2015-05-01

    Somatostatin analogs (SSAs) were initially developed as antisecretory agents used for the control of hormonal syndromes associated with neuroendocrine tumors (NETs). In recent years, accumulating evidence has also supported their role as antiproliferative agents in well or moderately differentiated NETs. The phase III PROMID trial demonstrated that octreotide long-acting repeatable (LAR) can significantly prolong time to progression among patients with metastatic midgut NETs. More recently, the randomized CLARINET trial reported a significant improvement in progression-free survival in a heterogeneous population of patients with gastroenteropancreatic (GEP)-NETs treated with depot lanreotide. Octreotide and lanreotide target somatostatin receptor subtypes in a similar fashion, and appear to be clinically interchangeable; however, comparative noninferiority trials have not been performed. Further studies are needed to evaluate the efficacy of novel SSAs such as pasireotide in the refractory setting, and the role of high-dose SSAs for symptom and tumor control. PMID:25911185

  4. Analog earthquakes

    SciTech Connect

    Hofmann, R.B.

    1995-09-01

    Analogs are used to understand complex or poorly understood phenomena for which little data may be available at the actual repository site. Earthquakes are complex phenomena, and they can have a large number of effects on the natural system, as well as on engineered structures. Instrumental data close to the source of large earthquakes are rarely obtained. The rare events for which measurements are available may be used, with modfications, as analogs for potential large earthquakes at sites where no earthquake data are available. In the following, several examples of nuclear reactor and liquified natural gas facility siting are discussed. A potential use of analog earthquakes is proposed for a high-level nuclear waste (HLW) repository.

  5. Triptycene analogs

    NASA Technical Reports Server (NTRS)

    Hua, Duy (Inventor); Perchellet, Jean-Pierre (Inventor)

    2004-01-01

    This invention provides analogs of triptycene which are useful as anticancer drugs, as well as for other uses. The potency of these compounds is in a similar magnitude as daunomycin, a currently used anticancer drug. Each compound of the invention produces one or more desired effects (blocking nucleoside transport, inhibiting nucleic acid or protein syntheses, decreasing the proliferation and viability of cancer cells, inducing DNA fragmentation or retaining their effectiveness against multidrug-resistant tumor cells).

  6. Science Teachers' Analogical Reasoning

    NASA Astrophysics Data System (ADS)

    Mozzer, Nilmara Braga; Justi, Rosária

    2013-08-01

    Analogies can play a relevant role in students' learning. However, for the effective use of analogies, teachers should not only have a well-prepared repertoire of validated analogies, which could serve as bridges between the students' prior knowledge and the scientific knowledge they desire them to understand, but also know how to introduce analogies in their lessons. Both aspects have been discussed in the literature in the last few decades. However, almost nothing is known about how teachers draw their own analogies for instructional purposes or, in other words, about how they reason analogically when planning and conducting teaching. This is the focus of this paper. Six secondary teachers were individually interviewed; the aim was to characterize how they perform each of the analogical reasoning subprocesses, as well as to identify their views on analogies and their use in science teaching. The results were analyzed by considering elements of both theories about analogical reasoning: the structural mapping proposed by Gentner and the analogical mechanism described by Vosniadou. A comprehensive discussion of our results makes it evident that teachers' content knowledge on scientific topics and on analogies as well as their pedagogical content knowledge on the use of analogies influence all their analogical reasoning subprocesses. Our results also point to the need for improving teachers' knowledge about analogies and their ability to perform analogical reasoning.

  7. Radioactive Decay - An Analog.

    ERIC Educational Resources Information Center

    McGeachy, Frank

    1988-01-01

    Presents an analog of radioactive decay that allows the student to grasp the concept of half life and the exponential nature of the decay process. The analog is devised to use small, colored, plastic poker chips or counters. Provides the typical data and a graph which supports the analog. (YP)

  8. Analog synthetic biology.

    PubMed

    Sarpeshkar, R

    2014-03-28

    We analyse the pros and cons of analog versus digital computation in living cells. Our analysis is based on fundamental laws of noise in gene and protein expression, which set limits on the energy, time, space, molecular count and part-count resources needed to compute at a given level of precision. We conclude that analog computation is significantly more efficient in its use of resources than deterministic digital computation even at relatively high levels of precision in the cell. Based on this analysis, we conclude that synthetic biology must use analog, collective analog, probabilistic and hybrid analog-digital computational approaches; otherwise, even relatively simple synthetic computations in cells such as addition will exceed energy and molecular-count budgets. We present schematics for efficiently representing analog DNA-protein computation in cells. Analog electronic flow in subthreshold transistors and analog molecular flux in chemical reactions obey Boltzmann exponential laws of thermodynamics and are described by astoundingly similar logarithmic electrochemical potentials. Therefore, cytomorphic circuits can help to map circuit designs between electronic and biochemical domains. We review recent work that uses positive-feedback linearization circuits to architect wide-dynamic-range logarithmic analog computation in Escherichia coli using three transcription factors, nearly two orders of magnitude more efficient in parts than prior digital implementations. PMID:24567476

  9. Nonvolatile Analog Memory

    NASA Technical Reports Server (NTRS)

    MacLeod, Todd C. (Inventor)

    2007-01-01

    A nonvolatile analog memory uses pairs of ferroelectric field effect transistors (FFETs). Each pair is defined by a first FFET and a second FFET. When an analog value is to be stored in one of the pairs, the first FFET has a saturation voltage applied thereto, and the second FFET has a storage voltage applied thereto that is indicative of the analog value. The saturation and storage voltages decay over time in accordance with a known decay function that is used to recover the original analog value when the pair of FFETs is read.

  10. Analog pulse processor

    DOEpatents

    Wessendorf, Kurt O.; Kemper, Dale A.

    2003-06-03

    A very low power analog pulse processing system implemented as an ASIC useful for processing signals from radiation detectors, among other things. The system incorporates the functions of a charge sensitive amplifier, a shaping amplifier, a peak sample and hold circuit, and, optionally, an analog to digital converter and associated drivers.

  11. Analog synthetic biology

    PubMed Central

    Sarpeshkar, R.

    2014-01-01

    We analyse the pros and cons of analog versus digital computation in living cells. Our analysis is based on fundamental laws of noise in gene and protein expression, which set limits on the energy, time, space, molecular count and part-count resources needed to compute at a given level of precision. We conclude that analog computation is significantly more efficient in its use of resources than deterministic digital computation even at relatively high levels of precision in the cell. Based on this analysis, we conclude that synthetic biology must use analog, collective analog, probabilistic and hybrid analog–digital computational approaches; otherwise, even relatively simple synthetic computations in cells such as addition will exceed energy and molecular-count budgets. We present schematics for efficiently representing analog DNA–protein computation in cells. Analog electronic flow in subthreshold transistors and analog molecular flux in chemical reactions obey Boltzmann exponential laws of thermodynamics and are described by astoundingly similar logarithmic electrochemical potentials. Therefore, cytomorphic circuits can help to map circuit designs between electronic and biochemical domains. We review recent work that uses positive-feedback linearization circuits to architect wide-dynamic-range logarithmic analog computation in Escherichia coli using three transcription factors, nearly two orders of magnitude more efficient in parts than prior digital implementations. PMID:24567476

  12. Challenges in Using Analogies

    ERIC Educational Resources Information Center

    Lin, Shih-Yin; Singh, Chandralekha

    2011-01-01

    Learning physics requires understanding the applicability of fundamental principles in a variety of contexts that share deep features. One way to help students learn physics is via analogical reasoning. Students can be taught to make an analogy between situations that are more familiar or easier to understand and another situation where the same…

  13. Hydraulic Capacitor Analogy

    ERIC Educational Resources Information Center

    Baser, Mustafa

    2007-01-01

    Students have difficulties in physics because of the abstract nature of concepts and principles. One of the effective methods for overcoming students' difficulties is the use of analogies to visualize abstract concepts to promote conceptual understanding. According to Iding, analogies are consistent with the tenets of constructivist learning…

  14. Meat analog: a review.

    PubMed

    Malav, O P; Talukder, S; Gokulakrishnan, P; Chand, S

    2015-01-01

    The health-conscious consumers are in search of nutritious and convenient food item which can be best suited in their busy life. The vegetarianism is the key for the search of such food which resembles the meat in respect of nutrition and sensory characters, but not of animal origin and contains vegetable or its modified form, this is the point when meat analog evolved out and gets shape. The consumers gets full satisfaction by consumption of meat analog due to its typical meaty texture, appearance and the flavor which are being imparted during the skilled production of meat analog. The supplement of protein in vegetarian diet through meat alike food can be fulfilled by incorporating protein-rich vegetative food grade materials in meat analog and by adopting proper technological process which can promote the proper fabrication of meat analog with acceptable meat like texture, appearance, flavor, etc. The easily available vegetables, cereals, and pulses in India have great advantages and prospects to be used in food products and it can improve the nutritional and functional characters of the food items. The various form and functional characters of food items are available world over and attracts the meat technologists and the food processors to bring some innovativeness in meat analog and its presentation and marketability so that the acceptability of meat analog can be overgrown by the consumers. PMID:24915320

  15. Fatty acid analogs

    DOEpatents

    Elmaleh, David R.; Livni, Eli

    1985-01-01

    In one aspect, a radioactively labeled analog of a fatty acid which is capable of being taken up by mammalian tissue and which exhibits an in vivo beta-oxidation rate below that with a corresponding radioactively labeled fatty acid.

  16. FGF growth factor analogs

    DOEpatents

    Zamora, Paul O.; Pena, Louis A.; Lin, Xinhua; Takahashi, Kazuyuki

    2012-07-24

    The present invention provides a fibroblast growth factor heparin-binding analog of the formula: ##STR00001## where R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, X, Y and Z are as defined, pharmaceutical compositions, coating compositions and medical devices including the fibroblast growth factor heparin-binding analog of the foregoing formula, and methods and uses thereof.

  17. 77 FR 63840 - Endocrinologic and Metabolic Drugs Advisory Committee; Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-17

    .... Pasireotide is an analog (a chemical compound that resembles another compound in structure) of somatostatin... disease who require medical intervention (Cushing's disease is a rare medical condition of...

  18. Electrical Circuits and Water Analogies

    ERIC Educational Resources Information Center

    Smith, Frederick A.; Wilson, Jerry D.

    1974-01-01

    Briefly describes water analogies for electrical circuits and presents plans for the construction of apparatus to demonstrate these analogies. Demonstrations include series circuits, parallel circuits, and capacitors. (GS)

  19. Analogical Reasoning in Geometry Education

    ERIC Educational Resources Information Center

    Magdas, Ioana

    2015-01-01

    The analogical reasoning isn't used only in mathematics but also in everyday life. In this article we approach the analogical reasoning in Geometry Education. The novelty of this article is a classification of geometrical analogies by reasoning type and their exemplification. Our classification includes: analogies for understanding and setting a…

  20. Digital and analog communication systems

    NASA Technical Reports Server (NTRS)

    Shanmugam, K. S.

    1979-01-01

    The book presents an introductory treatment of digital and analog communication systems with emphasis on digital systems. Attention is given to the following topics: systems and signal analysis, random signal theory, information and channel capacity, baseband data transmission, analog signal transmission, noise in analog communication systems, digital carrier modulation schemes, error control coding, and the digital transmission of analog signals.

  1. Electrical analogous in viscoelasticity

    NASA Astrophysics Data System (ADS)

    Ala, Guido; Di Paola, Mario; Francomano, Elisa; Li, Yan; Pinnola, Francesco P.

    2014-07-01

    In this paper, electrical analogous models of fractional hereditary materials are introduced. Based on recent works by the authors, mechanical models of materials viscoelasticity behavior are firstly approached by using fractional mathematical operators. Viscoelastic models have elastic and viscous components which are obtained by combining springs and dashpots. Various arrangements of these elements can be used, and all of these viscoelastic models can be equivalently modeled as electrical circuits, where the spring and dashpot are analogous to the capacitance and resistance, respectively. The proposed models are validated by using modal analysis. Moreover, a comparison with numerical experiments based on finite difference time domain method shows that, for long time simulations, the correct time behavior can be obtained only with modal analysis. The use of electrical analogous in viscoelasticity can better reveal the real behavior of fractional hereditary materials.

  2. An Interesting Analogy

    ERIC Educational Resources Information Center

    Pacheco, Jose M.; Fernandez, Isabel

    2002-01-01

    The aim of this note is to give some insight into the formal unity of a very applicable area of mathematics by showing an interesting analogy between the weak part of the Rouche-Frobenius theorem and the existence result for the initial value problem for the general first-order linear two-dimensional PDE.

  3. How Analogy Drives Physics

    SciTech Connect

    Hofstadter, Doug

    2004-05-05

    Many new ideas in theoretical physics come from analogies to older ideas in physics. For instance, the abstract notion of 'isospin' (or isotopic spin) originated in the prior concept of 'spin' (quantized angular momentum); likewise, the concept of 'phonon' (quantum of sound, or quantized collective excitation of a crystal) was based on the prior concept of 'photon' (quantum of light, or quantized element of the electromagnetic field). But these two examples, far from being exceptions, in fact represent the bread and butter of inventive thinking in physics. In a nutshell, intraphysics analogy-making -- borrowing by analogy with something already known in another area of physics -- is central to the progress of physics. The aim of this talk is to reveal the pervasiveness -- indeed, the indispensability -- of this kind of semi-irrational, wholly intuitive type of thinking (as opposed to more deductive mathematical inference) in the mental activity known as 'doing physics'. Speculations as to why wild analogical leaps are so crucial to the act of discovery in physics (as opposed to other disciplines) will be offered.

  4. Reasoning through Instructional Analogies

    ERIC Educational Resources Information Center

    Kapon, Shulamit; diSessa, Andrea A.

    2012-01-01

    This article aims to account for students' assessments of the plausibility and applicability of analogical explanations, and individual differences in these assessments, by analyzing properties of students' underlying knowledge systems. We developed a model of explanation and change in explanation focusing on knowledge elements that provide a…

  5. Quantum Analog Computing

    NASA Technical Reports Server (NTRS)

    Zak, M.

    1998-01-01

    Quantum analog computing is based upon similarity between mathematical formalism of quantum mechanics and phenomena to be computed. It exploits a dynamical convergence of several competing phenomena to an attractor which can represent an externum of a function, an image, a solution to a system of ODE, or a stochastic process.

  6. Learning by Analogical Bootstrapping.

    ERIC Educational Resources Information Center

    Miao, Chun-Hui; Kurtz, Kenneth J.; Gentner, Dedre

    2001-01-01

    Reports on research into whether mutual alignment of partially known situations can be an effective strategy when compared to the common procedure of drawing analogies from a well understood situation to one that is poorly understood. Results suggest that such mutual alignment is an effective means of promoting insight. (MM)

  7. Analogy, explanation, and proof

    PubMed Central

    Hummel, John E.; Licato, John; Bringsjord, Selmer

    2014-01-01

    People are habitual explanation generators. At its most mundane, our propensity to explain allows us to infer that we should not drink milk that smells sour; at the other extreme, it allows us to establish facts (e.g., theorems in mathematical logic) whose truth was not even known prior to the existence of the explanation (proof). What do the cognitive operations underlying the inference that the milk is sour have in common with the proof that, say, the square root of two is irrational? Our ability to generate explanations bears striking similarities to our ability to make analogies. Both reflect a capacity to generate inferences and generalizations that go beyond the featural similarities between a novel problem and familiar problems in terms of which the novel problem may be understood. However, a notable difference between analogy-making and explanation-generation is that the former is a process in which a single source situation is used to reason about a single target, whereas the latter often requires the reasoner to integrate multiple sources of knowledge. This seemingly small difference poses a challenge to the task of marshaling our understanding of analogical reasoning to understanding explanation. We describe a model of explanation, derived from a model of analogy, adapted to permit systematic violations of this one-to-one mapping constraint. Simulation results demonstrate that the resulting model can generate explanations for novel explananda and that, like the explanations generated by human reasoners, these explanations vary in their coherence. PMID:25414655

  8. Arterial Pressure Analog.

    ERIC Educational Resources Information Center

    Heusner, A. A.; Tracy, M. L.

    1980-01-01

    Describes a simple hydraulic analog which allows students to explore some physical aspects of the cardiovascular system and provides them with a means to visualize and conceptualize these basic principles. Simulates the behavior of arterial pressure in response to changes in heart rate, stroke volume, arterial compliance, and peripheral…

  9. Terrestrial Spaceflight Analogs: Antarctica

    NASA Technical Reports Server (NTRS)

    Crucian, Brian

    2013-01-01

    Alterations in immune cell distribution and function, circadian misalignment, stress and latent viral reactivation appear to persist during Antarctic winterover at Concordia Station. Some of these changes are similar to those observed in Astronauts, either during or immediately following spaceflight. Others are unique to the Concordia analog. Based on some initial immune data and environmental conditions, Concordia winterover may be an appropriate analog for some flight-associated immune system changes and mission stress effects. An ongoing smaller control study at Neumayer III will address the influence of the hypoxic variable. Changes were observed in the peripheral blood leukocyte distribution consistent with immune mobilization, and similar to those observed during spaceflight. Alterations in cytokine production profiles were observed during winterover that are distinct from those observed during spaceflight, but potentially consistent with those observed during persistent hypobaric hypoxia. The reactivation of latent herpesviruses was observed during overwinter/isolation, that is consistently associated with dysregulation in immune function.

  10. Analogy Construction versus Analogy Solution, and Their Influence on Transfer

    ERIC Educational Resources Information Center

    Harpaz-Itay, Yifat; Kaniel, Shlomo; Ben-Amram, Einat

    2006-01-01

    This study compares transfer performed by subjects trained to solve verbal analogies, with transfer by subjects trained to construct them. The first group (n = 57) received instruction in a strategy to solve verbal analogies and the second group (n = 66) was trained in strategies for constructing such analogies. Before and after intervention, all…

  11. Analog storage integrated circuit

    DOEpatents

    Walker, J. T.; Larsen, R. S.; Shapiro, S. L.

    1989-01-01

    A high speed data storage array is defined utilizing a unique cell design for high speed sampling of a rapidly changing signal. Each cell of the array includes two input gates between the signal input and a storage capacitor. The gates are controlled by a high speed row clock and low speed column clock so that the instantaneous analog value of the signal is only sampled and stored by each cell on coincidence of the two clocks.

  12. Analog storage integrated circuit

    DOEpatents

    Walker, J.T.; Larsen, R.S.; Shapiro, S.L.

    1989-03-07

    A high speed data storage array is defined utilizing a unique cell design for high speed sampling of a rapidly changing signal. Each cell of the array includes two input gates between the signal input and a storage capacitor. The gates are controlled by a high speed row clock and low speed column clock so that the instantaneous analog value of the signal is only sampled and stored by each cell on coincidence of the two clocks. 6 figs.

  13. Antarctic analogs for Enceladus

    NASA Astrophysics Data System (ADS)

    Murray, A. E.; Andersen, D. T.; McKay, C. P.

    2014-12-01

    Enceladus is a new world for Astrobiology. The Cassini discovery of the icy plume emanating from the South Polar region indicates an active world, where detection of water, organics, sodium, and nano-particle silica in the plume strongly suggests that the source is a subsurface salty ocean reservoir. Recent gravity data from Cassini confirms the presence of a regional sea extending north to 50°S. An ocean habitat under a thick ice cover is perhaps a recurring theme in the Outer Solar System, but what makes Enceladus unique is that the plume jetting out into space is carrying samples of this ocean. Therefore, through the study of Enceladus' plumes we can gain new insights not only of a possible habitable world in the Solar Systems, but also about the formation and evolution of other icy-satellites. Cassini has been able to fly through this plume - effectively sampling the ocean. It is time to plan for future missions that do more detailed analyses, possibly return samples back to Earth and search for evidence of life. To help prepare for such missions, the need for earth-based analog environments is essential for logistical, methodological (life detection) and theoretical development. We have undertaken studies of two terrestrial environments that are close analogs to Enceladus' ocean: Lake Vida and Lake Untersee - two ice-sealed Antarctic lakes that represent physical, chemical and possibly biological analogs for Enceladus. By studying the diverse biology and physical and chemical constraints to life in these two unique lakes we will begin to understand the potential habitability of Enceladus and other icy moons, including possible sources of nutrients and energy, which together with liquid water are the key ingredients for life. Analog research such as this will also enable us to develop and test new strategies to search for evidence of life on Enceladus.

  14. A Transiting Jupiter Analog

    NASA Astrophysics Data System (ADS)

    Kipping, D. M.; Torres, G.; Henze, C.; Teachey, A.; Isaacson, H.; Petigura, E.; Marcy, G. W.; Buchhave, L. A.; Chen, J.; Bryson, S. T.; Sandford, E.

    2016-04-01

    Decadal-long radial velocity surveys have recently started to discover analogs to the most influential planet of our solar system, Jupiter. Detecting and characterizing these worlds is expected to shape our understanding of our uniqueness in the cosmos. Despite the great successes of recent transit surveys, Jupiter analogs represent a terra incognita, owing to the strong intrinsic bias of this method against long orbital periods. We here report on the first validated transiting Jupiter analog, Kepler-167e (KOI-490.02), discovered using Kepler archival photometry orbiting the K4-dwarf KIC-3239945. With a radius of (0.91+/- 0.02) {R}{{J}}, a low orbital eccentricity ({0.06}-0.04+0.10), and an equilibrium temperature of (131+/- 3) K, Kepler-167e bears many of the basic hallmarks of Jupiter. Kepler-167e is accompanied by three Super-Earths on compact orbits, which we also validate, leaving a large cavity of transiting worlds around the habitable-zone. With two transits and continuous photometric coverage, we are able to uniquely and precisely measure the orbital period of this post snow-line planet (1071.2323 ± 0.0006d), paving the way for follow-up of this K = 11.8 mag target.

  15. Neural Analog Information Processing

    NASA Astrophysics Data System (ADS)

    Hecht-Nielsen, Robert

    1982-07-01

    Neural Analog Information Processing (NAIP) is an effort to develop general purpose pattern classification architectures based upon biological information processing principles. This paper gives an overview of NAIP and its relationship to the previous work in neural modeling from which its fundamental principles are derived. It also presents a theorem concerning the stability of response of a slab (a two dimensional array of identical simple processing units) to time-invariant (spatial) patterns. An experiment (via computer emulation) demonstrating classification of a spatial pattern by a simple, but complete NAIP architecture is described. A concept for hardware implementation of NAIP architectures is briefly discussed.

  16. Antarctic Space Analog Program

    NASA Technical Reports Server (NTRS)

    Palinkas, Lawrence A; Gunderson, E. K. Eric; Johnson, Jeffrey C.; Holland, Albert W.

    1998-01-01

    The primary aim of this project was to examine group dynamics and individual performance in extreme, isolated environments and identify human factors requirements for long-duration space missions using data collected in an analog environment. Specifically, we wished to determine: 1) the characteristics of social relations in small groups of individuals living and working together in extreme, isolated environments, and 2) the environmental, social and psychological determinants of performance effectiveness in such groups. These two issues were examined in six interrelated studies using data collected in small, isolated research stations in Antarctica from 1963 to the present. Results from these six studies indicated that behavior and performance on long-duration space flights is likely to be seasonal or cyclical, situational, social, and salutogenic in nature. The project responded to two NASA program emphases for FY 1997 as described in the NRA: 1) the primary emphasis of the Behavior and Performance Program on determining long-term individual and group performance responses to space, identifying critical factors affecting those responses and understanding underlying mechanisms involved in behavior and performance, and developing and using ground-based models and analogs for studying space-related behavior and performance; and 2) the emphasis of the Data Analysis Program on extended data analysis. Results from the study were used to develop recommendations for the design and development of pre-flight crew training and in-flight psychological countermeasures for long-duration manned space missions.

  17. Vorticity in analog gravity

    NASA Astrophysics Data System (ADS)

    Cropp, Bethan; Liberati, Stefano; Turcati, Rodrigo

    2016-06-01

    In the analog gravity framework, the acoustic disturbances in a moving fluid can be described by an equation of motion identical to a relativistic scalar massless field propagating in curved space-time. This description is possible only when the fluid under consideration is barotropic, inviscid, and irrotational. In this case, the propagation of the perturbations is governed by an acoustic metric that depends algebrically on the local speed of sound, density, and the background flow velocity, the latter assumed to be vorticity-free. In this work we provide a straightforward extension in order to go beyond the irrotational constraint. Using a charged—relativistic and nonrelativistic—Bose–Einstein condensate as a physical system, we show that in the low-momentum limit and performing the eikonal approximation we can derive a d’Alembertian equation of motion for the charged phonons where the emergent acoustic metric depends on flow velocity in the presence of vorticity.

  18. Analog and digital signal processing

    NASA Astrophysics Data System (ADS)

    Baher, H.

    The techniques of signal processing in both the analog and digital domains are addressed in a fashion suitable for undergraduate courses in modern electrical engineering. The topics considered include: spectral analysis of continuous and discrete signals, analysis of continuous and discrete systems and networks using transform methods, design of analog and digital filters, digitization of analog signals, power spectrum estimation of stochastic signals, FFT algorithms, finite word-length effects in digital signal processes, linear estimation, and adaptive filtering.

  19. Pictorial Analogies XII: Stoichiometric Calculations.

    ERIC Educational Resources Information Center

    Fortman, John J.

    1994-01-01

    Pictorial analogies that demonstrate concepts of amounts allow instructors to teach that in stoichiometric problems, the number--or moles--of molecules of a chemical is what matters, even though it must be measured in masses or volumes. Analogies to stoichiometric relationships include the ratio of four wheels to one body in making wagons and…

  20. Isolated transfer of analog signals

    NASA Technical Reports Server (NTRS)

    Bezdek, T.

    1974-01-01

    Technique transfers analog signal levels across high isolation boundary without circuit performance being affected by magnetizing reactance or leakage inductance. Transfers of analog information across isolated boundary are made by interrupting signal flow, with switch, in such a manner as to produce alternating signal which is applied to transformer.

  1. Natural analog studies: Licensing perspective

    SciTech Connect

    Bradbury, J.W.

    1995-09-01

    This report describes the licensing perspective of the term {open_quotes}natural analog studies{close_quotes} as used in CFR Part 60. It describes the misunderstandings related to its definition which has become evident during discussions at the U.S Nuclear Regulatory Commission meetings and tries to clarify the appropriate applications of natural analog studies to aspects of repository site characterization.

  2. Conjecturing via Reconceived Classical Analogy

    ERIC Educational Resources Information Center

    Lee, Kyeong-Hwa; Sriraman, Bharath

    2011-01-01

    Analogical reasoning is believed to be an efficient means of problem solving and construction of knowledge during the search for and the analysis of new mathematical objects. However, there is growing concern that despite everyday usage, learners are unable to transfer analogical reasoning to learning situations. This study aims at facilitating…

  3. Drawing Analogies in Environmental Education

    ERIC Educational Resources Information Center

    Affifi, Ramsey

    2014-01-01

    Reconsidering the origin, process, and outcomes of analogy-making suggests practices for environmental educators who strive to disengage humans from the isolating illusions of dichotomizing frameworks. We can view analogies as outcomes of developmental processes within which human subjectivity is but an element, threading our sense of self back…

  4. Introduction to Analog Field Testing

    NASA Video Gallery

    NASA tests systems and operational concepts in analog environments, which include locations underwater, in the arctic, on terrestrial impact craters, in the desert, and on the International Space S...

  5. Flight Analogs (Bed Rest Research)

    NASA Video Gallery

    Flight Analogs / Bed Rest Research Projects provide NASA with a ground based research platform to complement space research. By mimicking the conditions of weightlessness in the human body here on ...

  6. Evaluating countermeasures in spaceflight analogs.

    PubMed

    Ploutz-Snyder, Lori

    2016-04-15

    Countermeasures are defined as solutions to prevent the undesirable physiologic outcomes associated with spaceflight. Spaceflight analogs provide a valuable opportunity for the evaluation of countermeasures because they allow for the evaluation of more subjects, more experimental control, and are considerably less expensive than actual spaceflight. The various human analogs have differing strengths and weaknesses with respect to the development and evaluation of countermeasures. The human analogs are briefly reviewed with a focus on their suitability for countermeasure evaluation. Bed rest is the most commonly used analog for evaluating countermeasures. While countermeasures are typically developed to target one or maybe two particular physiologic issues, it is increasingly important to evaluate all of the organ systems to discern whether they might be unintended consequences on nontargeted tissues. In preparation for Mars exploration it will be necessary to fully integrate countermeasures to protect all organ systems. The synergistic and antagonistic effects of multiple countermeasures needs to be the focus of future work. PMID:26662054

  7. Solving a problem by analogy

    NASA Astrophysics Data System (ADS)

    Easton, Don

    1999-03-01

    This note is a description of a student solution to a problem. I found the solution exciting because it exemplifies the kind of solution by analogy that Feynman describes in The Feynman Lectures on Physics.

  8. The Robustness of Acoustic Analogies

    NASA Technical Reports Server (NTRS)

    Freund, J. B.; Lele, S. K.; Wei, M.

    2004-01-01

    Acoustic analogies for the prediction of flow noise are exact rearrangements of the flow equations N(right arrow q) = 0 into a nominal sound source S(right arrow q) and sound propagation operator L such that L(right arrow q) = S(right arrow q). In practice, the sound source is typically modeled and the propagation operator inverted to make predictions. Since the rearrangement is exact, any sufficiently accurate model of the source will yield the correct sound, so other factors must determine the merits of any particular formulation. Using data from a two-dimensional mixing layer direct numerical simulation (DNS), we evaluate the robustness of two analogy formulations to different errors intentionally introduced into the source. The motivation is that since S can not be perfectly modeled, analogies that are less sensitive to errors in S are preferable. Our assessment is made within the framework of Goldstein's generalized acoustic analogy, in which different choices of a base flow used in constructing L give different sources S and thus different analogies. A uniform base flow yields a Lighthill-like analogy, which we evaluate against a formulation in which the base flow is the actual mean flow of the DNS. The more complex mean flow formulation is found to be significantly more robust to errors in the energetic turbulent fluctuations, but its advantage is less pronounced when errors are made in the smaller scales.

  9. Producing and recognizing analogical relations.

    PubMed

    Lipkens, Regina; Hayes, Steven C

    2009-01-01

    Analogical reasoning is an important component of intelligent behavior, and a key test of any approach to human language and cognition. Only a limited amount of empirical work has been conducted from a behavior analytic point of view, most of that within Relational Frame Theory (RFT), which views analogy as a matter of deriving relations among relations. The present series of four studies expands previous work by exploring the applicability of this model of analogy to topography-based rather than merely selection-based responses and by extending the work into additional relations, including nonsymmetrical ones. In each of the four studies participants pretrained in contextual control over nonarbitrary stimulus relations of sameness and opposition, or of sameness, smaller than, and larger than, learned arbitrary stimulus relations in the presence of these relational cues and derived analogies involving directly trained relations and derived relations of mutual and combinatorial entailment, measured using a variety of productive and selection-based measures. In Experiment 1 participants successfully recognized analogies among stimulus networks containing same and opposite relations; in Experiment 2 analogy was successfully used to extend derived relations to pairs of novel stimuli; in Experiment 3 the procedure used in Experiment 1 was extended to nonsymmetrical comparative relations; in Experiment 4 the procedure used in Experiment 2 was extended to nonsymmetrical comparative relations. Although not every participant showed the effects predicted, overall the procedures occasioned relational responses consistent with an RFT account that have not yet been demonstrated in a behavior-analytic laboratory setting, including productive responding on the basis of analogies. PMID:19230515

  10. Biomimetic Analogs for Collagen Biomineralization

    PubMed Central

    Gu, L.; Kim, Y.K.; Liu, Y.; Ryou, H.; Wimmer, C.E.; Dai, L.; Arola, D.D.; Looney, S.W.; Pashley, D.H.; Tay, F.R.

    2011-01-01

    Inability of chemical phosphorylation of sodium trimetaphosphate to induce intrafibrillar mineralization of type I collagen may be due to the failure to incorporate a biomimetic analog to stabilize amorphous calcium phosphates (ACP) as nanoprecursors. This study investigated adsorption/desorption characteristics of hydrolyzed and pH-adjusted sodium trimetaphosphate (HPA-Na3P3O9) to collagen. Based on those results, a 5-minute treatment time with 2.8 wt% HPA-Na3P3O9 was used in a single-layer reconstituted collagen model to confirm that both the ACP-stabilization analog and matrix phosphoprotein analog must be present for intrafibrillar mineralization. The results of that model were further validated by complete remineralization of phosphoric-acid-etched dentin treated with the matrix phosphoprotein analog and lined with a remineralizing lining composite, and with the ACP-stabilization analog supplied in simulated body fluid. An understanding of the basic processes involved in intrafibrillar mineralization of reconstituted collagen fibrils facilitates the design of novel tissue engineering materials for hard tissue repair and regeneration. PMID:20940362

  11. Crows spontaneously exhibit analogical reasoning.

    PubMed

    Smirnova, Anna; Zorina, Zoya; Obozova, Tanya; Wasserman, Edward

    2015-01-19

    Analogical reasoning is vital to advanced cognition and behavioral adaptation. Many theorists deem analogical thinking to be uniquely human and to be foundational to categorization, creative problem solving, and scientific discovery. Comparative psychologists have long been interested in the species generality of analogical reasoning, but they initially found it difficult to obtain empirical support for such thinking in nonhuman animals (for pioneering efforts, see [2, 3]). Researchers have since mustered considerable evidence and argument that relational matching-to-sample (RMTS) effectively captures the essence of analogy, in which the relevant logical arguments are presented visually. In RMTS, choice of test pair BB would be correct if the sample pair were AA, whereas choice of test pair EF would be correct if the sample pair were CD. Critically, no items in the correct test pair physically match items in the sample pair, thus demanding that only relational sameness or differentness is available to support accurate choice responding. Initial evidence suggested that only humans and apes can successfully learn RMTS with pairs of sample and test items; however, monkeys have subsequently done so. Here, we report that crows too exhibit relational matching behavior. Even more importantly, crows spontaneously display relational responding without ever having been trained on RMTS; they had only been trained on identity matching-to-sample (IMTS). Such robust and uninstructed relational matching behavior represents the most convincing evidence yet of analogical reasoning in a nonprimate species, as apes alone have spontaneously exhibited RMTS behavior after only IMTS training. PMID:25532894

  12. All-optical analog comparator.

    PubMed

    Li, Pu; Yi, Xiaogang; Liu, Xianglian; Zhao, Dongliang; Zhao, Yongpeng; Wang, Yuncai

    2016-01-01

    An analog comparator is one of the core units in all-optical analog-to-digital conversion (AO-ADC) systems, which digitizes different amplitude levels into two levels of logical '1' or '0' by comparing with a defined decision threshold. Although various outstanding photonic ADC approaches have been reported, almost all of them necessitate an electrical comparator to carry out this binarization. The use of an electrical comparator is in contradiction to the aim of developing all-optical devices. In this work, we propose a new concept of an all-optical analog comparator and numerically demonstrate an implementation based on a quarter-wavelength-shifted distributed feedback laser diode (QWS DFB-LD) with multiple quantum well (MQW) structures. Our results show that the all-optical comparator is very well suited for true AO-ADCs, enabling the whole digital conversion from an analog optical signal (continuous-time signal or discrete pulse signal) to a binary representation totally in the optical domain. In particular, this all-optical analog comparator possesses a low threshold power (several mW), high extinction ratio (up to 40 dB), fast operation rate (of the order of tens of Gb/s) and a step-like transfer function. PMID:27550874

  13. All-optical analog comparator

    PubMed Central

    Li, Pu; Yi, Xiaogang; Liu, Xianglian; Zhao, Dongliang; Zhao, Yongpeng; Wang, Yuncai

    2016-01-01

    An analog comparator is one of the core units in all-optical analog-to-digital conversion (AO-ADC) systems, which digitizes different amplitude levels into two levels of logical ‘1’ or ‘0’ by comparing with a defined decision threshold. Although various outstanding photonic ADC approaches have been reported, almost all of them necessitate an electrical comparator to carry out this binarization. The use of an electrical comparator is in contradiction to the aim of developing all-optical devices. In this work, we propose a new concept of an all-optical analog comparator and numerically demonstrate an implementation based on a quarter-wavelength-shifted distributed feedback laser diode (QWS DFB-LD) with multiple quantum well (MQW) structures. Our results show that the all-optical comparator is very well suited for true AO-ADCs, enabling the whole digital conversion from an analog optical signal (continuous-time signal or discrete pulse signal) to a binary representation totally in the optical domain. In particular, this all-optical analog comparator possesses a low threshold power (several mW), high extinction ratio (up to 40 dB), fast operation rate (of the order of tens of Gb/s) and a step-like transfer function. PMID:27550874

  14. Digital plus analog output encoder

    NASA Technical Reports Server (NTRS)

    Hafle, R. S. (Inventor)

    1976-01-01

    The disclosed encoder is adapted to produce both digital and analog output signals corresponding to the angular position of a rotary shaft, or the position of any other movable member. The digital signals comprise a series of binary signals constituting a multidigit code word which defines the angular position of the shaft with a degree of resolution which depends upon the number of digits in the code word. The basic binary signals are produced by photocells actuated by a series of binary tracks on a code disc or member. The analog signals are in the form of a series of ramp signals which are related in length to the least significant bit of the digital code word. The analog signals are derived from sine and cosine tracks on the code disc.

  15. Multilateral Collaborations in Analog Research

    NASA Technical Reports Server (NTRS)

    Cromwell, R. l.

    2016-01-01

    International collaborations in studies utilizing ground-based space flight analogs are an effective means for answering research questions common to participating agencies. These collaborations bring together worldwide experts to solve important space research questions. By collaborating unnecessary duplication of science is reduced, and the efficiency of analog use is improved. These studies also share resources among agencies for cost effective solutions to study implementation. Recently, NASA has engaged in collaborations with international partners at a variety of analog sites. The NASA Human Exploration Research Analog (HERA) is currently hosting investigator studies from NASA and from the German Space Agency (DLR). These isolation studies will answer questions in the areas of team cohesion, sleep and circadian rhythms, and neurobehavioral correlates to function. Planning for the next HERA campaign is underway as proposal selections are being made from the International Life Sciences Research Announcement (ILSRA). Studies selected from the ILSRA will be conducted across 4 HERA missions in 2017. NASA is planning collaborative studies with DLR at the :envihab facility in Cologne, Germany. Investigations were recently selected to study the effects of 0.5% CO2 exposure over 30 days of bed rest. These studies will help to determine the fidelity of this ground-based analog for studying the visual impairment intracranial pressure syndrome. NASA is also planning a multilateral collaboration at :envihab with DLR and the European Space Agency (ESA) to examine artificial gravity as a countermeasure to mitigate the effects of 60 days of bed rest. NASA is also considering collaborations with the Russian Institute for Biomedical Problems (IBMP) in studies that will utilize their Ground-based Experimental Facility (NEK). The NEK is comprised of 4 interconnected modules and a Martian surface simulator. This isolation analog can support 3 -10 crew members for long duration

  16. Analog video to ARINC 818

    NASA Astrophysics Data System (ADS)

    Grunwald, Paul

    2015-05-01

    Many commercial and military aircraft still use analog video, such as RS-170, RS-343, or STANEG 3350. Though the individual digital components many be inexpensive, the cost to certify and retrofit an entire aircraft fleet may be prohibitively expensive. A partial or incremental upgrade program where analog cameras remain in use but data is converted and processed digitally can be an attractive option. This paper describes Great River Technology's experience in converting multiple channels of RS-170 and multiplexing them through a concentrator to put them onto a single fiber or cable. The paper will also discuss alternative architectures and how ARINC 818 can be utilized with legacy systems.

  17. Analog enhancement of radiographic images

    NASA Technical Reports Server (NTRS)

    Baily, N. A.; Nachazel, R. J.

    1976-01-01

    The paper shows how analog methods for edge sharpening, contrast enhancement, and expansion of the range of gray levels of particular interest are effective for easy on-line application to video viewing of X-ray roentgenograms or to fluoroscopy. The technique for analog enhancement of radiographic images is a modified version of the system designed by Fuchs et al. (1972), whereby an all directional second derivative signal called detail signal is used to produce both vertical and horizontal enhancement of the image. Particular attention is given to noise filtration and contrast enhancement. Numerous radiographs supplement the text.

  18. Optical analogs of model atoms in fields

    SciTech Connect

    Milonni, P.W.

    1991-05-02

    The equivalence of the paraxial wave equation to a time-dependent Schroedinger equation is exploited to construct optical analogs of model atoms in monochromatic fields. The approximation of geometrical optics provides the analog of the corresponding classical mechanics. Optical analogs of Rabi oscillations, photoionization, stabilization, and the Kramers-Henneberger transformation are discussed. One possibility for experimental realization of such optical analogs is proposed. These analogs may be useful for studies of quantum chaos'' when the ray trajectories are chaotic. 9 refs.

  19. Terrestrial analogs for space exploration habitation systems

    NASA Technical Reports Server (NTRS)

    Campbell, Paul D.; Brown, Jeri W.

    1992-01-01

    The Space Exploration Initiative (SEI) can use early earth-based analogs to simulate many aspects of space flight missions and system operation. These analogs can thus provide information supporting future missions to the moon and to Mars. A study was performed to investigate the potential of terrestrial analogs in simulating human space exploration missions. The study resulted in preliminary requirements and concepts for analog habitation systems, and further study in this area is necessary for SEI terrestrial analog development.

  20. Analogies and "Modeling Analogies" in Teaching: Some Examples in Basic Electricity.

    ERIC Educational Resources Information Center

    Dupin, J. J.; Johsua, S.

    1989-01-01

    Investigates the effect of modeling analogy on learning of the concepts of electricity in grade 6, 8, and 10. Describes 2 analogies (train analogy and thermal analogy) with diagrams and examples. Discusses the accessibility, transferability, and difficulty of each analogy. Reports treatment effect and some further implications. (YP)

  1. Multichannel analog temperature sensing system

    NASA Astrophysics Data System (ADS)

    Gribble, R.

    1985-08-01

    A multichannel system that protects the numerous and costly water-cooled magnet coils on the translation section of the FRX-C/T magnetic fusion experiment is described. The system comprises a thermistor for each coil, a constant current circuit for each thermistor, and a multichannel analog-to-digital converter interfaced to the computer.

  2. Analog Simulation of a Laser.

    ERIC Educational Resources Information Center

    Kessler, Gary

    1982-01-01

    Presents an analog simulation of laser properties (finding time evolution of the intensity of a ruby laser pulse) which serves as the basis of a three-four hour laboratory experiment. Includes programs for solution to rate equations of a three-level laser and production of a giant pulse in a ruby laser. (Author/SK)

  3. Understanding & Teaching Genetics Using Analogies

    ERIC Educational Resources Information Center

    Woody, Scott; Himelblau, Ed

    2013-01-01

    We present a collection of analogies that are intended to help students better understand the foreign and often nuanced vocabulary of the genetics curriculum. Why is it called the "wild type"? What is the difference between a locus, a gene, and an allele? What is the functional (versus a rule-based) distinction between dominant and…

  4. Algicidal Activity of Stilbene Analogs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As part of our continuing search for natural product and natural product-based compounds for the control of off-flavor in catfish, a total of twenty nine stilbene analogs were synthesized and evaluated for algicidal activity against the 2-methylisoborneol (MIB)-producing cyanobacterium Oscillatoria ...

  5. Bayesian Analogy with Relational Transformations

    ERIC Educational Resources Information Center

    Lu, Hongjing; Chen, Dawn; Holyoak, Keith J.

    2012-01-01

    How can humans acquire relational representations that enable analogical inference and other forms of high-level reasoning? Using comparative relations as a model domain, we explore the possibility that bottom-up learning mechanisms applied to objects coded as feature vectors can yield representations of relations sufficient to solve analogy…

  6. Mathematical Analogy and Metaphorical Insight

    ERIC Educational Resources Information Center

    Zwicky, Jan

    2010-01-01

    How are we to understand the power of certain literary metaphors? The author argues that the apprehension of good metaphors is importantly similar to the apprehension of fruitful mathematical analogies: both involve a structural realignment of vision. The author then explores consequences of this claim, drawing conceptually significant parallels…

  7. International Alligator Rivers Analog Project

    SciTech Connect

    Bichard, G.F.

    1988-01-01

    The Australian Nuclear Science and Technology Organization (ANSTO), the Japan Atomic Energy Research Institute, the Swedish Nuclear Power Inspectorate, the U.K. Department of the Environment, the US Nuclear Regulatory Commission (NRC), and the Power Reactor and Nuclear Fuel Development Corporation of Japan are participating under the aegis of the Nuclear Energy Agency in the International Alligator Rivers Analog Project. The project has a duration of 3 yr, starting in 1988. The project has grown out of a research program on uranium ore bodies as analogs of high-level waste (HLW) repositories undertaken by ANSTO supported by the NRC. A primary objective of the project is to develop an approach to radionuclide transport model validation that may be used by the participants to support assessments of the safety of radioactive waste repositories. The approach involves integrating mathematical and physical modeling with hydrological and geochemical field and laboratory investigations of the analog site. The Koongarra uranium ore body has been chosen as the analog site because it has a secondary ore body that has formed over the past million years as a result of leaching by groundwater flowing through fractures in the primary ore body.

  8. Analogy of the Cell Project

    ERIC Educational Resources Information Center

    Science Scope, 2005

    2005-01-01

    In this project, students compare the makeup of a cell to an everyday working unit or system. They create a three-dimensional object that represents their analogy. For example, students could create a car motor or manufacturing plant. (Of course, this is totally hand-created by them, so it can be a homemade re-creation of a system, not an actual…

  9. Analog Input Data Acquisition Software

    NASA Technical Reports Server (NTRS)

    Arens, Ellen

    2009-01-01

    DAQ Master Software allows users to easily set up a system to monitor up to five analog input channels and save the data after acquisition. This program was written in LabVIEW 8.0, and requires the LabVIEW runtime engine 8.0 to run the executable.

  10. Geometrical Analogies in Mathematics Lessons

    ERIC Educational Resources Information Center

    Eid, Wolfram

    2007-01-01

    A typical form of thinking to approach problem solutions humanly is thinking in analogous structures. Therefore school, especially mathematical lessons should help to form and to develop corresponding heuristic abilities of the pupils. In the contribution, a summary of possibilities of mathematics lessons regarding this shall particularly be…

  11. Bayesian analogy with relational transformations.

    PubMed

    Lu, Hongjing; Chen, Dawn; Holyoak, Keith J

    2012-07-01

    How can humans acquire relational representations that enable analogical inference and other forms of high-level reasoning? Using comparative relations as a model domain, we explore the possibility that bottom-up learning mechanisms applied to objects coded as feature vectors can yield representations of relations sufficient to solve analogy problems. We introduce Bayesian analogy with relational transformations (BART) and apply the model to the task of learning first-order comparative relations (e.g., larger, smaller, fiercer, meeker) from a set of animal pairs. Inputs are coded by vectors of continuous-valued features, based either on human magnitude ratings, normed feature ratings (De Deyne et al., 2008), or outputs of the topics model (Griffiths, Steyvers, & Tenenbaum, 2007). Bootstrapping from empirical priors, the model is able to induce first-order relations represented as probabilistic weight distributions, even when given positive examples only. These learned representations allow classification of novel instantiations of the relations and yield a symbolic distance effect of the sort obtained with both humans and other primates. BART then transforms its learned weight distributions by importance-guided mapping, thereby placing distinct dimensions into correspondence. These transformed representations allow BART to reliably solve 4-term analogies (e.g., larger:smaller::fiercer:meeker), a type of reasoning that is arguably specific to humans. Our results provide a proof-of-concept that structured analogies can be solved with representations induced from unstructured feature vectors by mechanisms that operate in a largely bottom-up fashion. We discuss potential implications for algorithmic and neural models of relational thinking, as well as for the evolution of abstract thought. PMID:22775500

  12. Classical Analog to Entanglement Reversibility

    NASA Astrophysics Data System (ADS)

    Chitambar, Eric; Fortescue, Ben; Hsieh, Min-Hsiu

    2015-08-01

    In this Letter we study the problem of secrecy reversibility. This asks when two honest parties can distill secret bits from some tripartite distribution pX Y Z and transform secret bits back into pX Y Z at equal rates using local operation and public communication. This is the classical analog to the well-studied problem of reversibly concentrating and diluting entanglement in a quantum state. We identify the structure of distributions possessing reversible secrecy when one of the honest parties holds a binary distribution, and it is possible that all reversible distributions have this form. These distributions are more general than what is obtained by simply constructing a classical analog to the family of quantum states known to have reversible entanglement. An indispensable tool used in our analysis is a conditional form of the Gács-Körner common information.

  13. Synaptic dynamics in analog VLSI.

    PubMed

    Bartolozzi, Chiara; Indiveri, Giacomo

    2007-10-01

    Synapses are crucial elements for computation and information transfer in both real and artificial neural systems. Recent experimental findings and theoretical models of pulse-based neural networks suggest that synaptic dynamics can play a crucial role for learning neural codes and encoding spatiotemporal spike patterns. Within the context of hardware implementations of pulse-based neural networks, several analog VLSI circuits modeling synaptic functionality have been proposed. We present an overview of previously proposed circuits and describe a novel analog VLSI synaptic circuit suitable for integration in large VLSI spike-based neural systems. The circuit proposed is based on a computational model that fits the real postsynaptic currents with exponentials. We present experimental data showing how the circuit exhibits realistic dynamics and show how it can be connected to additional modules for implementing a wide range of synaptic properties. PMID:17716003

  14. Battery hydrometer with analog output

    SciTech Connect

    Patis, B.L.

    1982-09-21

    There is disclosed a battery hydrometer for providing an analog electrical signal having a magnitude related to the specific gravity of a battery electrolyte. The hydrometer includes a source of radiation for providing a detectable beam of radiation and a piston member arranged to be submerged within the electrolyte and to intercept and modulate the beam of radiation in response to the specific gravity of the electrolyte. The piston member is suspended within the electrolyte by a spring which exerts a compressive force upon the piston member against which the electrolyte must act. The hydrometer further includes a radiation detector aligned with the radiation source for providing an analog electrical signal having a magnitude responsive to the modulated beam of radiation.

  15. Analog Nonvolatile Computer Memory Circuits

    NASA Technical Reports Server (NTRS)

    MacLeod, Todd

    2007-01-01

    In nonvolatile random-access memory (RAM) circuits of a proposed type, digital data would be stored in analog form in ferroelectric field-effect transistors (FFETs). This type of memory circuit would offer advantages over prior volatile and nonvolatile types: In a conventional complementary metal oxide/semiconductor static RAM, six transistors must be used to store one bit, and storage is volatile in that data are lost when power is turned off. In a conventional dynamic RAM, three transistors must be used to store one bit, and the stored bit must be refreshed every few milliseconds. In contrast, in a RAM according to the proposal, data would be retained when power was turned off, each memory cell would contain only two FFETs, and the cell could store multiple bits (the exact number of bits depending on the specific design). Conventional flash memory circuits afford nonvolatile storage, but they operate at reading and writing times of the order of thousands of conventional computer memory reading and writing times and, hence, are suitable for use only as off-line storage devices. In addition, flash memories cease to function after limited numbers of writing cycles. The proposed memory circuits would not be subject to either of these limitations. Prior developmental nonvolatile ferroelectric memories are limited to one bit per cell, whereas, as stated above, the proposed memories would not be so limited. The design of a memory circuit according to the proposal must reflect the fact that FFET storage is only partly nonvolatile, in that the signal stored in an FFET decays gradually over time. (Retention times of some advanced FFETs exceed ten years.) Instead of storing a single bit of data as either a positively or negatively saturated state in a ferroelectric device, each memory cell according to the proposal would store two values. The two FFETs in each cell would be denoted the storage FFET and the control FFET. The storage FFET would store an analog signal value

  16. Simple Electronic Analog of a Josephson Junction.

    ERIC Educational Resources Information Center

    Henry, R. W.; And Others

    1981-01-01

    Demonstrates that an electronic Josephson junction analog constructed from three integrated circuits plus an external reference oscillator can exhibit many of the circuit phenomena of a real Josephson junction. Includes computer and other applications of the analog. (Author/SK)

  17. Basic Electricity--a Novel Analogy.

    ERIC Educational Resources Information Center

    Grant, Richard

    1996-01-01

    Uses the analogy of water flow to introduce concepts in basic electricity. Presents a demonstration that uses this analogy to help students grasp the relationship between current, voltage, and resistance. (JRH)

  18. Thermal analog device reduces machining errors

    NASA Technical Reports Server (NTRS)

    Mcclure, E. R.

    1972-01-01

    Thermal analog devices predict thermal expansion and contraction of machine structures subjected to various heat inputs. Analog devices correct positioning of machine tools to compensate for distortion of machine frame.

  19. Hegel, Analogy, and Extraterrestrial Life

    NASA Astrophysics Data System (ADS)

    Ross, Joseph T.

    Georg Wilhelm Friedrich Hegel rejected the possibility of life outside of the Earth, according to several scholars of extraterrestrial life. Their position is that the solar system and specifically the planet Earth is the unique place in the cosmos where life, intelligence, and rationality can be. The present study offers a very different interpretation of Hegel's statements about the place of life on Earth by suggesting that, although Hegel did not believe that there were other solar systems where rationality is present, he did in fact suggest that planets in general, not the Earth exclusively, have life and possibly also intelligent inhabitants. Analogical syllogisms are superficial, according to Hegel, insofar as they try to conclude that there is life on the Moon even though there is no evidence of water or air on that body. Similar analogical arguments for life on the Sun made by Johann Elert Bode and William Herschel were considered by Hegel to be equally superficial. Analogical arguments were also used by astronomers and philosophers to suggest that life could be found on other planets in our solar system. Hegel offers no critique of analogical arguments for life on other planets, and in fact Hegel believed that life would be found on other planets. Planets, after all, have meteorological processes and therefore are "living" according to his philosophical account, unlike the Moon, Sun, and comets. Whereas William Herschel was already finding great similarities between the Sun and the stars and had extended these similarities to the property of having planets or being themselves inhabitable worlds, Hegel rejected this analogy. The Sun and stars have some properties in common, but for Hegel one cannot conclude from these similarities to the necessity that stars have planets. Hegel's arguments against the presence of life in the solar system were not directed against other planets, but rather against the Sun and Moon, both of which he said have a different

  20. Science Teachers' Analogical Reasoning

    ERIC Educational Resources Information Center

    Mozzer, Nilmara Braga; Justi, Rosária

    2013-01-01

    Analogies can play a relevant role in students' learning. However, for the effective use of analogies, teachers should not only have a well-prepared repertoire of validated analogies, which could serve as bridges between the students' prior knowledge and the scientific knowledge they desire them to understand, but also know how to…

  1. Reasoning by Analogy in Constructing Mathematical Ideas.

    ERIC Educational Resources Information Center

    English, Lyn D.

    A powerful way of understanding something new is by analogy with something already known. An analogy is defined as a mapping from one structure, which is already known (the base or source), to another structure that is to be inferred or discovered (the target). The research community has given considerable attention to analogical reasoning in the…

  2. Classical analog of quantum phase

    SciTech Connect

    Ord, G.N.

    1992-07-01

    A modified version of the Feynman relativistic chessboard model (FCM) is investigated in which the paths involved are spirals in the space-time. Portions of the paths in which the particle`s proper time is reversed are interpreted in terms of antiparticles. With this intepretation the particle-antiparticle field produced by such trajectories provides a classical analog of the phase associated with particle paths in the unmodified FCM. It is shwon that in the nonrelativistic limit the resulting kernel is the correct Dirac propagator and that particle-antiparticle symmetry is in this case responsible for quantum interference. 7 refs., 3 figs.

  3. Approaches to synthetic platelet analogs.

    PubMed

    Modery-Pawlowski, Christa L; Tian, Lewis L; Pan, Victor; McCrae, Keith R; Mitragotri, Samir; Sen Gupta, Anirban

    2013-01-01

    Platelet transfusion is routinely used for treating bleeding complications in patients with hematologic or oncologic clotting disorders, chemo/radiotherapy-induced myelosuppression, trauma and surgery. Currently, these transfusions mostly use allogeneic platelet concentrates, while products like lyophilized platelets, cold-stored platelets and infusible platelet membranes are under investigation. These natural platelet-based products pose considerable risks of contamination, resulting in short shelf-life (3-5 days). Recent advances in pathogen reduction technologies have increased shelf-life to ~7 days. Furthermore, natural platelets are short in supply and also cause several biological side effects. Hence, there is significant clinical interest in platelet-mimetic synthetic analogs that can allow long storage-life and minimum side effects. Accordingly, several designs have been studied which decorate synthetic particles with motifs that promote platelet-mimetic adhesion or aggregation. Recent refinement in this design involves combining the adhesion and aggregation functionalities on a single particle platform. Further refinement is being focused on constructing particles that also mimic natural platelet's shape, size and elasticity, to influence margination and wall-interaction. The optimum design of a synthetic platelet analog would require efficient integration of platelet's physico-mechanical properties and biological functionalities. We present a comprehensive review of these approaches and provide our opinion regarding the future directions of this research. PMID:23092864

  4. Analog computation with dynamical systems

    NASA Astrophysics Data System (ADS)

    Siegelmann, Hava T.; Fishman, Shmuel

    1998-09-01

    Physical systems exhibit various levels of complexity: their long term dynamics may converge to fixed points or exhibit complex chaotic behavior. This paper presents a theory that enables to interpret natural processes as special purpose analog computers. Since physical systems are naturally described in continuous time, a definition of computational complexity for continuous time systems is required. In analogy with the classical discrete theory we develop fundamentals of computational complexity for dynamical systems, discrete or continuous in time, on the basis of an intrinsic time scale of the system. Dissipative dynamical systems are classified into the computational complexity classes P d, Co-RP d, NP d and EXP d, corresponding to their standard counterparts, according to the complexity of their long term behavior. The complexity of chaotic attractors relative to regular ones leads to the conjecture P d ≠ NP d. Continuous time flows have been proven useful in solving various practical problems. Our theory provides the tools for an algorithmic analysis of such flows. As an example we analyze the continuous Hopfield network.

  5. Automatic activation of categorical and abstract analogical relations in analogical reasoning.

    PubMed

    Green, Adam E; Fugelsang, Jonathan A; Dunbar, Kevin N

    2006-10-01

    We examined activation of concepts during analogical reasoning. Subjects made either analogical judgments or categorical judgments about four-word sets. After each four-word set, they named the ink color of a single word in a modified Stroop task. Words that referred to category relations were primed (as indicated by longer response times on Stroop color naming) subsequent to analogical judgments and categorical judgments. This finding suggests that activation of category concepts plays a fundamental role in analogical thinking. When colored words referred to analogical relations, priming occurred subsequent to analogical judgments, but not to categorical judgments, even though identical four-word stimuli were used for both types of judgments. This finding lends empirical support to the hypothesis that, when people comprehend the analogy between two items, they activate an abstract analogical relation that is distinct from the specific content items that compose the analogy. PMID:17263066

  6. Analog computing by Brewster effect.

    PubMed

    Youssefi, Amir; Zangeneh-Nejad, Farzad; Abdollahramezani, Sajjad; Khavasi, Amin

    2016-08-01

    Optical computing has emerged as a promising candidate for real-time and parallel continuous data processing. Motivated by recent progresses in metamaterial-based analog computing [Science343, 160 (2014)SCIEAS0036-807510.1126/science.1242818], we theoretically investigate the realization of two-dimensional complex mathematical operations using rotated configurations, recently reported in [Opt. Lett.39, 1278 (2014)OPLEDP0146-959210.1364/OL.39.001278]. Breaking the reflection symmetry, such configurations could realize both even and odd Green's functions associated with spatial operators. Based on such an appealing theory and by using the Brewster effect, we demonstrate realization of a first-order differentiator. Such an efficient wave-based computation method not only circumvents the major potential drawbacks of metamaterials, but also offers the most compact possible device compared to conventional bulky lens-based optical signal and data processors. PMID:27472595

  7. QCD analogy for quantum gravity

    NASA Astrophysics Data System (ADS)

    Holdom, Bob; Ren, Jing

    2016-06-01

    Quadratic gravity presents us with a renormalizable, asymptotically free theory of quantum gravity. When its couplings grow strong at some scale, as in QCD, then this strong scale sets the Planck mass. QCD has a gluon that does not appear in the physical spectrum. Quadratic gravity has a spin-2 ghost that we conjecture does not appear in the physical spectrum. We discuss how the QCD analogy leads to this conjecture and to the possible emergence of general relativity. Certain aspects of the QCD path integral and its measure are also similar for quadratic gravity. With the addition of the Einstein-Hilbert term, quadratic gravity has a dimensionful parameter that seems to control a quantum phase transition and the size of a mass gap in the strong phase.

  8. [Active vitamin D3 analog].

    PubMed

    Takata, Shinjiro

    2015-10-01

    Vitamin D is a fat-soluble vitamin and exerts effects on skeletal and extraskeletal health in children and adults of all ages. Vitamin D insufficiency is related to low muscle strength, increasing body sway, falls in the elderly. Supplementation with vitamin D reduces risk of osteoporotic fracture, and improves muscle strength and postural balance to prevent the elderly from fall. The preferred vitamin D analog for daily supplementation is cholecalciferol (vitamin D3). The active form of vitamin D3 is 1,25-dihydroxy-vitamin D3. Alfacalcidol, calcitriol and eldecalcitol are used to treat osteoporosis in Japan. Randomized placebo-controlled, double-blinded clinical trial for osteoporotic subjects showed that eldecalcitol is more efficacious to increase bone mineral density and prevent vertebral and wrist fractures in osteoporotic patients with vitamin D sufficiency than alfacalcidol. PMID:26529933

  9. The Young Solar Analogs Project

    NASA Astrophysics Data System (ADS)

    Gray, Richard O.; Saken, J. M.; Corbally, C. J.; Fuller, V.; Kahvaz, Y.; Lambert, R.; Newsome, I.; Seeds, M.

    2013-01-01

    We are carrying out a long-term project of measuring chromospheric activity and brightness variations in 31 young solar analogs (YSAs) using facilities at the Dark Sky Observatory (DSO - Appalachian State University) and the Vatican Advanced Technology Telescope (VATT). These YSAs are solar-type (spectral types F8 - K2) stars with ages ranging from 0.3 - 1.5 Gyr. The goal of this project is to gain better understanding of the magnetic activity of the early Sun, and especially how that activity may have impacted the development of life on the Earth. This project will also yield insights into the space environments experienced by young Earth analogs. We are currently in the 6th year of spectroscopic measurements of these stars: these data include Ca II H & K chromospheric flux measurements, and narrow-band measurements in the photospheric G-band, both obtained with the G/M spectrograph on the DSO 32-inch telescope. We will present evidence of activity cycles in a number of our stars, as well as periods determined from rotational modulation of the spectroscopic indices. The relationship between the Ca II activity index and the G-band index will be explored. NSF support for our project has provided funds for the construction of a robotic photometric telescope to monitor the program stars in a 5-passband system (Strömgren-v, Johnson-Cousins B, V, and R, and a 3-nm wide Hα filter). The robotic telescope has been functional since April 2012 and observes the program stars on every clear night; combined with the Piggy-back telescope attached to the DSO 32-inch, we now have photometric observations on over 130 nights stretching over nearly 2 years. We will examine the relationships between variations in the Ca II H & K index, the G-band index and the photometric bands. This project is supported by the National Science Foundation, grant AST-1109158.

  10. The Young Solar Analogs Project

    NASA Astrophysics Data System (ADS)

    Gray, Richard O.; Saken, J. M.; Corbally, C. J.; Seeds, M. F.; Morrison, S. S.

    2012-01-01

    We are carrying out a long-term project of measuring chromospheric activity and brightness variations in 31 young solar analogs (YSAs) using the Dark Sky Observatory (DSO -- Appalachian State University) 32-inch telescope and the G/M spectrograph. These YSAs are solar-type (spectral types F8 - K2) stars with ages ranging from 0.3 - 1.5 Gyr. The goal of this project is to gain better understanding of the magnetic activity of the early Sun, and especially how that activity may have impacted the development of life on the Earth. This project will also yield insights into the space environments experienced by young Earth analogs. We are currently in our 5th year of obtaining Ca II K & H chromospheric flux measurements, and are beginning to see signs of long-term activity cycles in a number of our stars. In addition, rotational modulation of the chromospheric fluxes is detectable in our data, and we have determined rotational periods for many of our stars. Short timescale increases in the K & H fluxes have been observed in a number of our stars; these events may be related to stellar flares. VATTSpec, a new moderate-resolution spectrograph on the 1.8-m Vatican Telescope in Arizona, has recently become involved with the project. This spectrograph will increase our ability to detect short-term changes in stellar activity on timescales of hours to minutes. We have been monitoring the program stars for one year in a multi-band photometric system consisting of Stromgren-v, and Johnson B, V, and R filters. We will soon add a narrow-band H-alpha filter to the system. Photometry is being carried out with a small piggy-back telescope on the 32-inch, but a robotic photometric telescope is currently being installed at DSO for this purpose. This project is supported by the National Science Foundation.

  11. Analysis of analogies used by science teachers

    NASA Astrophysics Data System (ADS)

    Dagher, Zoubeida R.

    Science teachers use analogies that display a rich variety of form and content. An account of science teacher analogies that relies solely on systems of analysis imported from other fields of inquiry tends to obscure the unique features of these analogies as they operate within classroom discourse. This study examines teachers' analogies in context and highlights some of their special characteristics. The purpose of this analysis is to increase our understanding of how analogies operate in naturalistic instructional settings and to generate new research questions about science teaching and learning in view of the broader dimensions of the curriculum.Science isa very human activity. It involves human actors and judgements, rivalries and antagonisms, mysteries and surprises, the creative use of metaphor and analogy. It is fallible, often uncertain, and sometimes creatively ambiguous [Lemke, 1990, p. 134].Received: 1 June 1993; Revised: 29 November 1993;

  12. Priming analogical reasoning with false memories.

    PubMed

    Howe, Mark L; Garner, Sarah R; Threadgold, Emma; Ball, Linden J

    2015-08-01

    Like true memories, false memories are capable of priming answers to insight-based problems. Recent research has attempted to extend this paradigm to more advanced problem-solving tasks, including those involving verbal analogical reasoning. However, these experiments are constrained inasmuch as problem solutions could be generated via spreading activation mechanisms (much like false memories themselves) rather than using complex reasoning processes. In three experiments we examined false memory priming of complex analogical reasoning tasks in the absence of simple semantic associations. In Experiment 1, we demonstrated the robustness of false memory priming in analogical reasoning when backward associative strength among the problem terms was eliminated. In Experiments 2a and 2b, we extended these findings by demonstrating priming on newly created homonym analogies that can only be solved by inhibiting semantic associations within the analogy. Overall, the findings of the present experiments provide evidence that the efficacy of false memory priming extends to complex analogical reasoning problems. PMID:25784574

  13. Terrestrial Analogs for Planetary Wrinkle Ridges

    NASA Technical Reports Server (NTRS)

    Plescia, J. B.; Golombek, M. P.

    1985-01-01

    Wrinkle ridges are common physiographic features on the terrestrial planets. Their origin has remained enigmatic, although two different types of models, volcanic and tectonic, have been proposed. The major impediment to deciphering the origin of wrinkle ridges has been the lack of a terrestrial analog. Seven terrestrial analogs were discussed, two in detail. Their implications for the origin for planetary wrinkle ridges were considered. All of the terrestrial analogs were formed in compressional environments and are the surface breaks of thrust faults.

  14. Fermilab accelerator control system: Analog monitoring facilities

    SciTech Connect

    Seino, K.; Anderson, L.; Smedinghoff, J.

    1987-10-01

    Thousands of analog signals are monitored in different areas of the Fermilab accelerator complex. For general purposes, analog signals are sent over coaxial or twinaxial cables with varying lengths, collected at fan-in boxes and digitized with 12 bit multiplexed ADCs. For higher resolution requirements, analog signals are digitized at sources and are serially sent to the control system. This paper surveys ADC subsystems that are used with the accelerator control systems and discusses practical problems and solutions, and it describes how analog data are presented on the console system.

  15. Properties of compressible elastica from relativistic analogy.

    PubMed

    Oshri, Oz; Diamant, Haim

    2016-01-21

    Kirchhoff's kinetic analogy relates the deformation of an incompressible elastic rod to the classical dynamics of rigid body rotation. We extend the analogy to compressible filaments and find that the extension is similar to the introduction of relativistic effects into the dynamical system. The extended analogy reveals a surprising symmetry in the deformations of compressible elastica. In addition, we use known results for the buckling of compressible elastica to derive the explicit solution for the motion of a relativistic nonlinear pendulum. We discuss cases where the extended Kirchhoff analogy may be useful for the study of other soft matter systems. PMID:26563905

  16. Robust hyperchaotic synchronization via analog transmission line

    NASA Astrophysics Data System (ADS)

    Sadoudi, S.; Tanougast, C.

    2016-02-01

    In this paper, a novel experimental chaotic synchronization technique via analog transmission is discussed. We demonstrate through Field-Programmable Gate Array (FPGA) implementation design the robust synchronization of two embedded hyperchaotic Lorenz generators interconnected with an analog transmission line. The basic idea of this work consists in combining a numerical generation of chaos and transmitting it with an analog signal. The numerical chaos allows to overcome the callback parameter mismatch problem and the analog transmission offers robust data security. As application, this technique can be applied to all families of chaotic systems including time-delayed chaotic systems.

  17. Real World: Analog Testing in Extreme Environments

    NASA Video Gallery

    See how NASA uses analog testing to simulate space exploration. Explore extreme environments like the Aquarius underwater laboratory in Key Largo, Florida. Find out how scientists use mathematical ...

  18. Expert analogy use in a naturalistic setting

    PubMed Central

    Kretz, Donald R.; Krawczyk, Daniel C.

    2014-01-01

    The use of analogy is an important component of human cognition. The type of analogy we produce and communicate depends heavily on a number of factors, such as the setting, the level of domain expertise present, and the speaker's goal or intent. In this observational study, we recorded economics experts during scientific discussion and examined the categorical distance and structural depth of the analogies they produced. We also sought to characterize the purpose of the analogies that were generated. Our results supported previous conclusions about the infrequency of superficial similarity in subject-generated analogs, but also showed that distance and depth characteristics were more evenly balanced than in previous observational studies. This finding was likely due to the nature of the goals of the participants, as well as the broader nature of their expertise. An analysis of analogical purpose indicated that the generation of concrete source examples of more general target concepts was most prevalent. We also noted frequent instances of analogies intended to form visual images of source concepts. Other common purposes for analogies were the addition of colorful speech, inclusion (i.e., subsumption) of a target into a source concept, or differentiation between source and target concepts. We found no association between depth and either of the other two characteristics, but our findings suggest a relationship between purpose and distance; i.e., that visual imagery typically entailed an outside-domain source whereas exemplification was most frequently accomplished using within-domain analogies. Overall, we observed a rich and diverse set of spontaneously produced analogical comparisons. The high degree of expertise within the observed group along with the richly comparative nature of the economics discipline likely contributed to this analogical abundance. PMID:25505437

  19. Novel Analog For Muscle Deconditioning

    NASA Technical Reports Server (NTRS)

    Ploutz-Snyder, Lori; Ryder, Jeff; Buxton, Roxanne; Redd, Elizabeth; Scott-Pandorf, Melissa; Hackney, Kyle; Fiedler, James; Bloomberg, Jacob

    2010-01-01

    Existing models of muscle deconditioning are cumbersome and expensive (ex: bedrest). We propose a new model utilizing a weighted suit to manipulate strength, power or endurance (function) relative to body weight (BW). Methods: 20 subjects performed 7 occupational astronaut tasks while wearing a suit weighted with 0-120% of BW. Models of the full relationship between muscle function/BW and task completion time were developed using fractional polynomial regression and verified by the addition of pre- and post-flight astronaut performance data using the same tasks. Spline regression was used to identify muscle function thresholds below which task performance was impaired. Results: Thresholds of performance decline were identified for each task. Seated egress & walk (most difficult task) showed thresholds of: leg press (LP) isometric peak force/BW of 18 N/kg, LP power/BW of 18 W/kg, LP work/ BW of 79 J/kg, knee extension (KE) isokinetic/BW of 6 Nm/Kg and KE torque/BW of 1.9 Nm/kg. Conclusions: Laboratory manipulation of strength / BW has promise as an appropriate analog for spaceflight-induced loss of muscle function for predicting occupational task performance and establishing operationally relevant exercise targets.

  20. Novel Analog For Muscle Deconditioning

    NASA Technical Reports Server (NTRS)

    Ploutz-Snyder, Lori; Ryder, Jeff; Buxton, Roxanne; Redd. Elizabeth; Scott-Pandorf, Melissa; Hackney, Kyle; Fiedler, James; Ploutz-Snyder, Robert; Bloomberg, Jacob

    2011-01-01

    Existing models (such as bed rest) of muscle deconditioning are cumbersome and expensive. We propose a new model utilizing a weighted suit to manipulate strength, power, or endurance (function) relative to body weight (BW). Methods: 20 subjects performed 7 occupational astronaut tasks while wearing a suit weighted with 0-120% of BW. Models of the full relationship between muscle function/BW and task completion time were developed using fractional polynomial regression and verified by the addition of pre-and postflightastronaut performance data for the same tasks. Splineregression was used to identify muscle function thresholds below which task performance was impaired. Results: Thresholds of performance decline were identified for each task. Seated egress & walk (most difficult task) showed thresholds of leg press (LP) isometric peak force/BW of 18 N/kg, LP power/BW of 18 W/kg, LP work/BW of 79 J/kg, isokineticknee extension (KE)/BW of 6 Nm/kg, and KE torque/BW of 1.9 Nm/kg.Conclusions: Laboratory manipulation of relative strength has promise as an appropriate analog for spaceflight-induced loss of muscle function, for predicting occupational task performance and establishing operationally relevant strength thresholds.

  1. Unpowered wireless analog resistance sensor

    NASA Astrophysics Data System (ADS)

    Andringa, Matthew M.; Neikirk, Dean P.; Wood, Sharon L.

    2004-07-01

    Our society depends heavily on a network of buildings, bridges and roadways. In order to properly maintain this civil infrastructure and avoid damage and costly repairs due to structural failure, it is necessary to monitor the health of these structures. Sensors must frequently be placed in inaccessible locations under harsh conditions and should ideally last the lifetime of the structure the sensors are monitoring. This paper presents the development of a low cost, passive, un-powered wireless analog resistance sensor. The sensor was originally designed for monitoring corrosion in concrete, but there are many other potential applications including remote temperature monitoring, embedded accelerometers, and embedded strain gauges. The passive wireless nature makes the sensor ideally suited for embedding in inaccessible locations under harsh conditions. The sensor consists of a resonant inductor-capacitor circuit containing a resistive transducer. The sensor is interrogated by measuring the impedance through a remote, magnetically coupled reader loop. The width of the resonance is directly related to the resistance of the transducer. The sensor has been simulated under a variety of conditions using a circuit model and compared to actual test sensors built and evaluated in the laboratory.

  2. Fault diagnosis of analog circuits

    SciTech Connect

    Bandler, J.W.; Salama, A.E.

    1985-08-01

    In this paper, various fault location techniques in analog networks are described and compared. The emphasis is on the more recent developments in the subject. Four main approaches for fault location are addressed, examined, and illustrated using simple network examples. In particular, we consider the fault dictionary approach, the parameter identification approach, the fault verification approach, and the approximation approach. Theory and algorithms that are associated with these approaches are reviewed and problems of their practical application are identified. Associated with the fault dictionary approach we consider fault dictionary construction techniques, methods of optimum measurement selection, different fault isolation criteria, and efficient fault simulation techniques. Parameter identification techniques that either utilize linear or nonlinear systems of equations to identify all network elements are examined very thoroughly. Under fault verification techniques we discuss node-fault diagnosis, branch-fault diagnosis, subnetwork testability conditions as well as combinatorial techniques, the failure bound technique, and the network decomposition technique. For the approximation approach we consider probabilistic methods and optimization-based methods. The artificial intelligence technique and the different measures of testability are also considered. The main features of the techniques considered are summarized in a comparative table. An extensive, but not exhaustive, bibliography is provided.

  3. Young Children's Analogical Reasoning in Science Domains

    ERIC Educational Resources Information Center

    Haglund, Jesper; Jeppsson, Fredrik; Andersson, Johanna

    2012-01-01

    This exploratory study in a classroom setting investigates first graders' (age 7-8 years, N = 25) ability to perform analogical reasoning and create their own analogies for two irreversible natural phenomena: mixing and heat transfer. We found that the children who contributed actively to a full-class discussion were consistently successful at…

  4. Using Analogies to Develop Conceptual Abilities.

    ERIC Educational Resources Information Center

    Jorgensen, Sally

    Because analogies are such powerful tools for communicating they should be exploited more consciously for instructional purposes. Unfortunately, analogies as a topic of investigation in the school curriculum tend to surface only as a subheading within a figurative language lesson in English class or as a test item on the SAT, MAT, or GRE. Analogy…

  5. Mathematical Analogs and the Teaching of Fractions.

    ERIC Educational Resources Information Center

    Charles, Kathy; Nason, Rod; Cooper, Tom

    The literature has noted that some mathematical analogs are more effective than others for the teaching of fractions. This study aimed to evaluate the efficacy of seven mathematical analogs commonly used in the teaching of the partitive quotient fraction construct. A sample of twelve purposively selected Year Three children were presented with…

  6. Antibacterial and Antibiofilm Activities of Makaluvamine Analogs

    PubMed Central

    Nijampatnam, Bhavitavya; Nadkarni, Dwayaja H.; Wu, Hui; Velu, Sadanandan E.

    2015-01-01

    Streptococcus mutans is a key etiological agent in the formation of dental caries. The major virulence factor is its ability to form biofilms. Inhibition of S. mutans biofilms offers therapeutic prospects for the treatment and the prevention of dental caries. In this study, 14 analogs of makaluvamine, a marine alkaloid, were evaluated for their antibacterial activity against S. mutans and for their ability to inhibit S. mutans biofilm formation. All analogs contained the tricyclic pyrroloiminoquinone core of makaluvamines. The structural variations of the analogs are on the amino substituents at the 7-position of the ring and the inclusion of a tosyl group on the pyrrole ring N of the makaluvamine core. The makaluvamine analogs displayed biofilm inhibition with IC50 values ranging from 0.4 μM to 88 μM. Further, the observed bactericidal activity of the majority of the analogs was found to be consistent with the anti-biofilm activity, leading to the conclusion that the anti-biofilm activity of these analogs stems from their ability to kill S. mutans. However, three of the most potent N-tosyl analogs showed biofilm IC50 values at least an order of magnitude lower than that of bactericidal activity, indicating that the biofilm activity of these analogs is more selective and perhaps independent of bactericidal activity. PMID:25767719

  7. Alaskan thermokarst terrain and possible Martian analog

    NASA Technical Reports Server (NTRS)

    Gatto, L. W.; Anderson, D. M.

    1975-01-01

    A first-order analog to Martian fretted terrain has been recognized on enhanced, ERTS-1 (Earth Resources Technology Satellite) imagery of Alaskan Arctic thermokarst terrain. The Alaskan analog displays flat-floored valleys and intervalley uplands characteristic of fretted terrain. The thermokarst terrain has formed in a manner similar to one of the processes postulated for the development of the Martian fretted terrain.

  8. Analog disc recorder system: operator's reference manual

    SciTech Connect

    O'Brien, J.D.; Smith, E.L.

    1984-07-01

    The FM Analog Disc Recorder System is a cost-efficient means of capturing analog transient data from many channels; it has high-frequency response and long record time. It can digitize recorded signals, correct internal distortion, and present the data as plots either on a CRT, hardcopy plot, or both. The system is easy to use, self-contained, and compact.

  9. Rotanone analogs: method of preparation and use

    DOEpatents

    VanBrocklin, Henry F; O& #x27; Neil, James P; Gibbs, Andrew R; Erathodiyil, Nandanan

    2013-10-08

    The present invention provides rotenone analogs and methods of making and using them. Labeled with single photon and positron emitting isotopes, the rotenone analogs of the present invention are useful in, for example, clinical imaging applications as tracers to measure cardiac blood flow and detect regions of ischemia.

  10. A Mechanical Analogy for the Photoelectric Effect

    ERIC Educational Resources Information Center

    Kovacevic, Milan S.; Djordjevich, Alexandar

    2006-01-01

    Analogy is a potent tool in the teacher's repertoire. It has been particularly well recognized in the teaching of science. However, careful planning is required for its effective application to prevent documented drawbacks when analogies are stretched too far. Befitting the occasion of the World Year of Physics commemorating Albert Einstein's 1905…

  11. An Analog Computer for Electronic Engineering Education

    ERIC Educational Resources Information Center

    Fitch, A. L.; Iu, H. H. C.; Lu, D. D. C.

    2011-01-01

    This paper describes a compact analog computer and proposes its use in electronic engineering teaching laboratories to develop student understanding of applications in analog electronics, electronic components, engineering mathematics, control engineering, safe laboratory and workshop practices, circuit construction, testing, and maintenance. The…

  12. A Computer Analogy for Illustrating Entropy Concepts.

    ERIC Educational Resources Information Center

    Powers, Michael H.

    1982-01-01

    Describes a computer program for Commodore PET (requiring 8K) which illustrates the statistical nature of entropy by providing a simple analogy. The analogy involves the distribution of objects free to move in a box divided into two compartments. A listing of program statements is also included. (JN)

  13. Analogical Processes and College Developmental Reading

    ERIC Educational Resources Information Center

    Paulson, Eric J.

    2014-01-01

    Although a solid body of research concerning the role of analogies in reading processes has emerged at a variety of age groups and reading proficiencies, few of those studies have focused on analogy use by readers enrolled in college developmental reading courses. The current study explores whether 232 students enrolled in mandatory (by placement…

  14. Play with Language: Overextensions as Analogies.

    ERIC Educational Resources Information Center

    Hudson, Judith; Nelson, Katherine

    1984-01-01

    Defines criteria to identify children's language overextensions and investigates how young children in the early stages of language acquisition rename objects analogically during a standardized play situation. Results indicate that analogic extensions are well within the capabilities of children from one year, eight months to two years, four…

  15. Piperazine-based nucleic acid analogs

    DOEpatents

    Schmidt, Jurgen; Silks, Louis A.; Michalczyk, Ryszard

    2005-01-11

    A novel nucleoside analog is disclosed which comprises a piperazine ring in the place of the ring ribose or deoxyribose sugar. Monomers utilizing a broad variety of nucleobases are disclosed, as well as oligomers comprising the monomers disclosed herein linked by a variety of linkages, including amide, phosphonamide, and sulfonamide linkages. A method of synthesizing the nucleoside analogs is also disclosed.

  16. The Pennies-as-Electrons Analogy

    ERIC Educational Resources Information Center

    Ashmann, Scott

    2009-01-01

    Everyday experiences familiarize students with the ways in which electricity is used, but often the underlying concepts remain a mystery. Teachers often use analogies to help students relate the flow of electrons to other common systems, but many times these analogies are incomplete and lead to more student misconceptions. However, the "pass the…

  17. The Multidimensionality of Verbal Analogy Items

    ERIC Educational Resources Information Center

    Ullstadius, Eva; Carlstedt, Berit; Gustafsson, Jan-Eric

    2008-01-01

    The influence of general and verbal ability on each of 72 verbal analogy test items were investigated with new factor analytical techniques. The analogy items together with the Computerized Swedish Enlistment Battery (CAT-SEB) were given randomly to two samples of 18-year-old male conscripts (n = 8566 and n = 5289). Thirty-two of the 72 items had…

  18. Predicting Naming Latencies with an Analogical Model

    ERIC Educational Resources Information Center

    Chandler, Steve

    2008-01-01

    Skousen's (1989, Analogical modeling of language, Kluwer Academic Publishers, Dordrecht) Analogical Model (AM) predicts behavior such as spelling pronunciation by comparing the characteristics of a test item (a given input word) to those of individual exemplars in a data set of previously encountered items. While AM and other exemplar-based models…

  19. Developing Analogy Cost Estimates for Space Missions

    NASA Technical Reports Server (NTRS)

    Shishko, Robert

    2004-01-01

    The analogy approach in cost estimation combines actual cost data from similar existing systems, activities, or items with adjustments for a new project's technical, physical or programmatic differences to derive a cost estimate for the new system. This method is normally used early in a project cycle when there is insufficient design/cost data to use as a basis for (or insufficient time to perform) a detailed engineering cost estimate. The major limitation of this method is that it relies on the judgment and experience of the analyst/estimator. The analyst must ensure that the best analogy or analogies have been selected, and that appropriate adjustments have been made. While analogy costing is common, there is a dearth of advice in the literature on the 'adjustment methodology', especially for hardware projects. This paper discusses some potential approaches that can improve rigor and repeatability in the analogy costing process.

  20. An Analog Earth Climate Model

    NASA Astrophysics Data System (ADS)

    Varekamp, J. C.

    2010-12-01

    The earth climate is broadly governed by the radiative power of the sun as well as the heat retention and convective cooling of the atmosphere. I have constructed an analog earth model for an undergraduate climate class that simulates mean climate using these three parameters. The ‘earth’ is a hollow, black, bronze sphere (4 cm diameter) mounted on a thin insulated rod, and illuminated by two opposite optic fibers, with light focused on the sphere by a set of lenses. The sphere is encased in a large double-walled aluminum cylinder (34 cm diameter by 26 cm high) with separate water cooling jackets at the top, bottom, and sides. The cylinder can be filled with a gas of choice at a variety of pressures or can be run in vacuum. The exterior is cladded with insulation, and the temperature of the sphere, atmosphere and walls is monitored with thermocouples. The temperature and waterflow of the three cooling jackets can be monitored to establish the energy output of the whole system; the energy input is the energy yield of the two optic fibers. A small IR transmissive lens at the top provides the opportunity to hook up the fiber of a hyper spectrometer to monitor the emission spectrum of the black ‘earth’ sphere. A pressure gauge and gas inlet-outlet system for flushing of the cell completes it. The heat yield of the cooling water at the top is the sum of the radiative and convective components, whereas the bottom jacket only carries off the radiative heat of the sphere. Undergraduate E&ES students at Wesleyan University have run experiments with dry air, pure CO2, N2 and Ar at 1 atmosphere, and a low vacuum run was accomplished to calibrate the energy input. For each experiment, the lights are flipped on, the temperature acquisition routine is activated, and the sphere starts to warm up until an equilibrium temperature has been reached. The lights are then flipped off and the cooling sequence towards ambient is registered. The energy input is constant for a given

  1. Investigation of Celestial Solid Analogs

    NASA Technical Reports Server (NTRS)

    Sievers, A. J.

    2003-01-01

    Our far infrared studies of both hydrophobic and hydrophilic aerogel grains have demonstrated that the mm and sub-mm wave absorption produced by the fundamental two level systems (TLS) mechanism represents a more significant contribution for these open grain structures than for bulk amorphous silicate grains. We found that the region with the anomalous temperature dependence of the spectral index due to the TLS excitations can extend in a fluffy material up to 80 per cm, which is well beyond its typical upper limit for bulk glasses. Currently there is no theoretical explanation for this surprising result. The effects of reduced dimensionality on the optical properties of carbonaceous grains have been studied with a systematic investigation of carbon aerogels. This spectroscopic approach has permitted a more reliable determination of the single grain mass normalized absorption coefficient based on the experimentally determined characteristics of the fluffy material rather than on first principles calculations involving the bulk properties of the substance. Our finding is that the electrical connectivity of the material is the main factor affecting its far infrared absorption coefficient. Another one of the main constituents of the interstellar dust, amorphous ice, has been investigated in the mm-wave region both in the high (HDA) and low (LDA) density amorphous phases and as a function of impurities. We found that doping either phase with ionic (LiCl) or molecular (methanol) impurities decreases the difference in the mm-wave absorption coefficient between the HDA and LDA ice phases so that the HDA spectrum can be used as an analog for impure ice absorption in the far infrared spectral region.

  2. Fostering Multilateral Involvement in Analog Research

    NASA Technical Reports Server (NTRS)

    Cromwell, Ronita L.

    2015-01-01

    International collaboration in space flight research is an effective means for conducting investigations and utilizing limited resources to the fullest extent. Through these multilateral collaborations mutual research questions can be investigated and resources contributed by each international partner to maximize the scientific benefits to all parties. Recently the international partners embraced this approach to initiate collaborations in ground-based space flight analog environments. In 2011, the International Analog Research Working Group was established, and later named the International Human Space Flight Analog Research Coordination Group (HANA). Among the goals of this working group are to 1) establish a framework to coordinate research campaigns, as appropriate, to minimize duplication of effort and enhance synergy; 2) define what analogs are best to use for collaborative interests; and 3) facilitate interaction between discipline experts in order to have the full benefit of international expertise. To accomplish these goals, HANA is currently engaged in developing international research campaigns in ground-based analogs. Plans are being made for an international solicitation for proposals to address research of common interest to all international partners. This solicitation with identify an analog environment that will best accommodate the types of investigations requested. Once selected, studies will be integrated into a campaign and implemented at the analog site. Through these combined efforts, research beneficial to all partners will be conducted efficiently to further address human risks of space exploration.

  3. Analogies: Explanatory Tools in Web-Based Science Instruction

    ERIC Educational Resources Information Center

    Glynn, Shawn M.; Taasoobshirazi, Gita; Fowler, Shawn

    2007-01-01

    This article helps designers of Web-based science instruction construct analogies that are as effective as those used in classrooms by exemplary science teachers. First, the authors explain what analogies are, how analogies foster learning, and what form analogies should take. Second, they discuss science teachers' use of analogies. Third, they…

  4. Analog detection for cavity lifetime spectroscopy

    DOEpatents

    Zare, Richard N.; Harb, Charles C.; Paldus, Barbara A.; Spence, Thomas G.

    2003-01-01

    An analog detection system for determining a ring-down rate or decay rate 1/.tau. of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

  5. Analog detection for cavity lifetime spectroscopy

    DOEpatents

    Zare, Richard N.; Harb, Charles C.; Paldus, Barbara A.; Spence, Thomas G.

    2001-05-15

    An analog detection system for determining a ring-down rate or decay rate 1/.tau. of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

  6. Programmable Analog-To-Digital Converter

    NASA Technical Reports Server (NTRS)

    Kist, Edward H., Jr.

    1993-01-01

    High-speed analog-to-digital converter with programmable voltage steps that can be changed during operation. Allows concentration of converter resolution over specific portion of waveform. Particularly useful in digitizing wind-shear radar and lidar return signals, in digital oscilloscopes, and other applications in which desirable to increase digital resolution over specific area of waveform while accepting lower resolution over rest of waveform. Effective increase in dynamic range achieved without increase in number of analog-to-digital converter bits. Enabling faster analog-to-digital conversion.

  7. Comparative conformational analysis of peptide T analogs

    NASA Astrophysics Data System (ADS)

    Akverdieva, Gulnare; Godjayev, Niftali; Akyuz, Sevim

    2009-01-01

    A series of peptide T analogs were investigated within the molecular mechanics framework. In order to determine the role of the aminoacid residues in spatial formation of peptide T the conformational peculiarities of the glycine-substituted analogs were investigated. The conformational profiles of some biologically tested analogs of this peptide were determined independently. The received data permit to assess the active form of this peptide. It is characterized by β-turn at the C-terminal physiologically active pentapeptide fragment of peptide molecule. The received results are important for the investigation of the structure-activity relationship and may be used at design of a rigid-molecule drug against HIV.

  8. Analog Computer Laboratory with Biological Examples.

    ERIC Educational Resources Information Center

    Strebel, Donald E.

    1979-01-01

    The use of biological examples in teaching applications of the analog computer is discussed and several examples from mathematical ecology, enzyme kinetics, and tracer dynamics are described. (Author/GA)

  9. Computer Analogies: Teaching Molecular Biology and Ecology.

    ERIC Educational Resources Information Center

    Rice, Stanley; McArthur, John

    2002-01-01

    Suggests that computer science analogies can aid the understanding of gene expression, including the storage of genetic information on chromosomes. Presents a matrix of biology and computer science concepts. (DDR)

  10. Identifying Solar Analogs in the Kepler Field

    NASA Astrophysics Data System (ADS)

    Buzasi, Derek L.; Lezcano, Andrew; Preston, Heather L.

    2014-06-01

    Since human beings live on a planet orbiting a G2 V star, to us perhaps the most intrinsically interesting category of stars about which planets have been discovered is solar analogs. While Kepler has observed more than 26000 targets which have effective temperatures within 100K of the Sun, many of these are not true solar analogs due to activity, surface gravity, metallicity, or other considerations. Here we combine ground-based measurements of effective temperature and metallicity with data on rotational periods and surface gravities derived from 16 quarters of Kepler observations to produce a near-complete sample of solar analogs in the Kepler field. We then compare the statistical distribution of stellar physical parameters, including activity level, for subsets of solar analogs consisting of KOIs and those with no detected exoplanets. Finally, we produce a list of potential solar twins in the Kepler field.

  11. An Electrical Analog Computer for Poets

    ERIC Educational Resources Information Center

    Bruels, Mark C.

    1972-01-01

    Nonphysics majors are presented with a direct current experiment beyond Ohms law and series and parallel laws. This involves construction of an analog computer from common rheostats and student-assembled voltmeters. (Author/TS)

  12. An Electronic Analog of the Diffraction Grating.

    ERIC Educational Resources Information Center

    MacLeod, A. M.

    1978-01-01

    Gives an outline description of electronic circuitry which is analogous to the optical diffraction grating or to crystals used in the Bragg reflection of X-rays or electron waves, and explains how to use it. (Author/GA)

  13. Optical analog-to-digital converter

    DOEpatents

    Vawter, G. Allen; Raring, James; Skogen, Erik J.

    2009-07-21

    An optical analog-to-digital converter (ADC) is disclosed which converts an input optical analog signal to an output optical digital signal at a sampling rate defined by a sampling optical signal. Each bit of the digital representation is separately determined using an optical waveguide interferometer and an optical thresholding element. The interferometer uses the optical analog signal and the sampling optical signal to generate a sinusoidally-varying output signal using cross-phase-modulation (XPM) or a photocurrent generated from the optical analog signal. The sinusoidally-varying output signal is then digitized by the thresholding element, which includes a saturable absorber or at least one semiconductor optical amplifier, to form the optical digital signal which can be output either in parallel or serially.

  14. Photoresistance analog multiplier has wide range

    NASA Technical Reports Server (NTRS)

    Hartenstein, R. G.

    1965-01-01

    Photoactivated bridge facilitates equal performance of analog multipliers over a wide frequency range. The multiplier operates from direct current to an upper frequency limited by either the light source or the closed-loop amplifier.

  15. The Analog (Computer) As a Physiology Adjunct.

    ERIC Educational Resources Information Center

    Stewart, Peter A.

    1979-01-01

    Defines and discusses the analog computer and its use in a physiology laboratory. Includes two examples: (1) The Respiratory Control Function and (2) CO-Two Control in the Respiratory System. Presents diagrams and mathematical models. (MA)

  16. NASA Now: Exploring Asteroids: An Analog Mission

    NASA Video Gallery

    NASA’s Extreme Environment Mission Operations, or NEEMO, project lead Bill Todd describes this analog mission and how aquanauts living and working in an undersea habitat are helping NASA prepare ...

  17. AMiBA Wideband Analog Correlator

    NASA Astrophysics Data System (ADS)

    Li, Chao-Te; Kubo, Derek Y.; Wilson, Warwick; Lin, Kai-Yang; Chen, Ming-Tang; Ho, P. T. P.; Chen, Chung-Cheng; Han, Chih-Chiang; Oshiro, Peter; Martin-Cocher, Pierre; Chang, Chia-Hao; Chang, Shu-Hao; Altamirano, Pablo; Jiang, Homin; Chiueh, Tzi-Dar; Lien, Chun-Hsien; Wang, Huei; Wei, Ray-Ming; Yang, Chia-Hsiang; Peterson, Jeffrey B.; Chang, Su-Wei; Huang, Yau-De; Hwang, Yuh-Jing; Kesteven, Michael; Koch, Patrick; Liu, Guo-Chin; Nishioka, Hiroaki; Umetsu, Keiichi; Wei, Tashun; Proty Wu, Jiun-Huei

    2010-06-01

    A wideband analog correlator has been constructed for the Yuan-Tseh Lee Array for Microwave Background Anisotropy. Lag correlators using analog multipliers provide large bandwidth and moderate frequency resolution. Broadband intermediate frequency distribution, back-end signal processing, and control are described. Operating conditions for optimum sensitivity and linearity are discussed. From observations, a large effective bandwidth of around 10 GHz has been shown to provide sufficient sensitivity for detecting cosmic microwave background variations.

  18. Analog hardware for learning neural networks

    NASA Technical Reports Server (NTRS)

    Eberhardt, Silvio P. (Inventor)

    1991-01-01

    This is a recurrent or feedforward analog neural network processor having a multi-level neuron array and a synaptic matrix for storing weighted analog values of synaptic connection strengths which is characterized by temporarily changing one connection strength at a time to determine its effect on system output relative to the desired target. That connection strength is then adjusted based on the effect, whereby the processor is taught the correct response to training examples connection by connection.

  19. Analog environments in space human factors

    NASA Technical Reports Server (NTRS)

    Connors, Mary M.

    1992-01-01

    An account is given of what has been learned from space analog environments, which mimic such significant features of space as isolation, confinement, risk, and deprivation; emphasis is placed on the especially successful environments constituted by extended submarine research, undersea habitats, and Antarctic station wintering. Attention is also given to the advantages and limitations of the use of analog environments for space human factors research, and possibilities for such research efforts' management.

  20. Synthetic heparin-binding growth factor analogs

    DOEpatents

    Pena, Louis A.; Zamora, Paul; Lin, Xinhua; Glass, John D.

    2007-01-23

    The invention provides synthetic heparin-binding growth factor analogs having at least one peptide chain that binds a heparin-binding growth factor receptor, covalently bound to a hydrophobic linker, which is in turn covalently bound to a non-signaling peptide that includes a heparin-binding domain. The synthetic heparin-binding growth factor analogs are useful as soluble biologics or as surface coatings for medical devices.

  1. ANALOG-TO-DIGITAL DATA CONVERTER

    DOEpatents

    Rodgers, G.W.; Althouse, J.E.; Anderson, D.P.; Bussey, G.R.; Minnear, L.H.

    1960-09-01

    Electrical apparatus is described, particularly useful in telemetry work, for converting analog signals into electrical pulses and recording them. An electronic editor commands the taking of signal readings at a frequency which varies according to linearity of the analog signal being converted. Readings of information signals are recorded, along with time base readings and serial numbering, if desired, on magnetic tape and the latter may be used to operate a computer or the like. Magnetic tape data may be transferred to punched cards.

  2. Analog modelling of obduction processes

    NASA Astrophysics Data System (ADS)

    Agard, P.; Zuo, X.; Funiciello, F.; Bellahsen, N.; Faccenna, C.; Savva, D.

    2012-04-01

    Obduction corresponds to one of plate tectonics oddities, whereby dense, oceanic rocks (ophiolites) are presumably 'thrust' on top of light, continental ones, as for the short-lived, almost synchronous Peri-Arabic obduction (which took place along thousands of km from Turkey to Oman in c. 5-10 Ma). Analog modelling experiments were performed to study the mechanisms of obduction initiation and test various triggering hypotheses (i.e., plate acceleration, slab hitting the 660 km discontinuity, ridge subduction; Agard et al., 2007). The experimental setup comprises (1) an upper mantle, modelled as a low-viscosity transparent Newtonian glucose syrup filling a rigid Plexiglas tank and (2) high-viscosity silicone plates (Rhodrosil Gomme with PDMS iron fillers to reproduce densities of continental or oceanic plates), located at the centre of the tank above the syrup to simulate the subducting and the overriding plates - and avoid friction on the sides of the tank. Convergence is simulated by pushing on a piston at one end of the model with velocities comparable to those of plate tectonics (i.e., in the range 1-10 cm/yr). The reference set-up includes, from one end to the other (~60 cm): (i) the piston, (ii) a continental margin containing a transition zone to the adjacent oceanic plate, (iii) a weakness zone with variable resistance and dip (W), (iv) an oceanic plate - with or without a spreading ridge, (v) a subduction zone (S) dipping away from the piston and (vi) an upper, active continental margin, below which the oceanic plate is being subducted at the start of the experiment (as is known to have been the case in Oman). Several configurations were tested and over thirty different parametric tests were performed. Special emphasis was placed on comparing different types of weakness zone (W) and the extent of mechanical coupling across them, particularly when plates were accelerated. Displacements, together with along-strike and across-strike internal deformation in all

  3. Optical domain analog to digital conversion methods and apparatus

    DOEpatents

    Vawter, Gregory A

    2014-05-13

    Methods and apparatus for optical analog to digital conversion are disclosed. An optical signal is converted by mapping the optical analog signal onto a wavelength modulated optical beam, passing the mapped beam through interferometers to generate analog bit representation signals, and converting the analog bit representation signals into an optical digital signal. A photodiode receives an optical analog signal, a wavelength modulated laser coupled to the photodiode maps the optical analog signal to a wavelength modulated optical beam, interferometers produce an analog bit representation signal from the mapped wavelength modulated optical beam, and sample and threshold circuits corresponding to the interferometers produce a digital bit signal from the analog bit representation signal.

  4. Analog Signal Correlating Using an Analog-Based Signal Conditioning Front End

    NASA Technical Reports Server (NTRS)

    Prokop, Norman; Krasowski, Michael

    2013-01-01

    This innovation is capable of correlating two analog signals by using an analog-based signal conditioning front end to hard-limit the analog signals through adaptive thresholding into a binary bit stream, then performing the correlation using a Hamming "similarity" calculator function embedded in a one-bit digital correlator (OBDC). By converting the analog signal into a bit stream, the calculation of the correlation function is simplified, and less hardware resources are needed. This binary representation allows the hardware to move from a DSP where instructions are performed serially, into digital logic where calculations can be performed in parallel, greatly speeding up calculations.

  5. Neurotoxic Alkaloids: Saxitoxin and Its Analogs

    PubMed Central

    Wiese, Maria; D’Agostino, Paul M.; Mihali, Troco K.; Moffitt, Michelle C.; Neilan, Brett A.

    2010-01-01

    Saxitoxin (STX) and its 57 analogs are a broad group of natural neurotoxic alkaloids, commonly known as the paralytic shellfish toxins (PSTs). PSTs are the causative agents of paralytic shellfish poisoning (PSP) and are mostly associated with marine dinoflagellates (eukaryotes) and freshwater cyanobacteria (prokaryotes), which form extensive blooms around the world. PST producing dinoflagellates belong to the genera Alexandrium, Gymnodinium and Pyrodinium whilst production has been identified in several cyanobacterial genera including Anabaena, Cylindrospermopsis, Aphanizomenon Planktothrix and Lyngbya. STX and its analogs can be structurally classified into several classes such as non-sulfated, mono-sulfated, di-sulfated, decarbamoylated and the recently discovered hydrophobic analogs—each with varying levels of toxicity. Biotransformation of the PSTs into other PST analogs has been identified within marine invertebrates, humans and bacteria. An improved understanding of PST transformation into less toxic analogs and degradation, both chemically or enzymatically, will be important for the development of methods for the detoxification of contaminated water supplies and of shellfish destined for consumption. Some PSTs also have demonstrated pharmaceutical potential as a long-term anesthetic in the treatment of anal fissures and for chronic tension-type headache. The recent elucidation of the saxitoxin biosynthetic gene cluster in cyanobacteria and the identification of new PST analogs will present opportunities to further explore the pharmaceutical potential of these intriguing alkaloids. PMID:20714432

  6. Analogy, higher order thinking, and education.

    PubMed

    Richland, Lindsey Engle; Simms, Nina

    2015-01-01

    Analogical reasoning, the ability to understand phenomena as systems of structured relationships that can be aligned, compared, and mapped together, plays a fundamental role in the technology rich, increasingly globalized educational climate of the 21st century. Flexible, conceptual thinking is prioritized in this view of education, and schools are emphasizing 'higher order thinking', rather than memorization of a cannon of key topics. The lack of a cognitively grounded definition for higher order thinking, however, has led to a field of research and practice with little coherence across domains or connection to the large body of cognitive science research on thinking. We review literature on analogy and disciplinary higher order thinking to propose that relational reasoning can be productively considered the cognitive underpinning of higher order thinking. We highlight the utility of this framework for developing insights into practice through a review of mathematics, science, and history educational contexts. In these disciplines, analogy is essential to developing expert-like disciplinary knowledge in which concepts are understood to be systems of relationships that can be connected and flexibly manipulated. At the same time, analogies in education require explicit support to ensure that learners notice the relevance of relational thinking, have adequate processing resources available to mentally hold and manipulate relations, and are able to recognize both the similarities and differences when drawing analogies between systems of relationships. PMID:26263071

  7. NaturAnalogs for the Unsaturated Zone

    SciTech Connect

    A. Simmons; A. Unger; M. Murrell

    2000-03-08

    The purpose of this Analysis/Model Report (AMR) is to document natural and anthropogenic (human-induced) analog sites and processes that are applicable to flow and transport processes expected to occur at the potential Yucca Mountain repository in order to build increased confidence in modeling processes of Unsaturated Zone (UZ) flow and transport. This AMR was prepared in accordance with ''AMR Development Plan for U0135, Natural Analogs for the UZ'' (CRWMS 1999a). Knowledge from analog sites and processes is used as corroborating information to test and build confidence in flow and transport models of Yucca Mountain, Nevada. This AMR supports the Unsaturated Zone (UZ) Flow and Transport Process Model Report (PMR) and the Yucca Mountain Site Description. The objectives of this AMR are to test and build confidence in the representation of UZ processes in numerical models utilized in the UZ Flow and Transport Model. This is accomplished by: (1) applying data from Boxy Canyon, Idaho in simulations of UZ flow using the same methodologies incorporated in the Yucca Mountain UZ Flow and Transport Model to assess the fracture-matrix interaction conceptual model; (2) Providing a preliminary basis for analysis of radionuclide transport at Pena Blanca, Mexico as an analog of radionuclide transport at Yucca Mountain; and (3) Synthesizing existing information from natural analog studies to provide corroborating evidence for representation of ambient and thermally coupled UZ flow and transport processes in the UZ Model.

  8. Analog forecasting with dynamics-adapted kernels

    NASA Astrophysics Data System (ADS)

    Zhao, Zhizhen; Giannakis, Dimitrios

    2016-09-01

    Analog forecasting is a nonparametric technique introduced by Lorenz in 1969 which predicts the evolution of states of a dynamical system (or observables defined on the states) by following the evolution of the sample in a historical record of observations which most closely resembles the current initial data. Here, we introduce a suite of forecasting methods which improve traditional analog forecasting by combining ideas from kernel methods developed in harmonic analysis and machine learning and state-space reconstruction for dynamical systems. A key ingredient of our approach is to replace single-analog forecasting with weighted ensembles of analogs constructed using local similarity kernels. The kernels used here employ a number of dynamics-dependent features designed to improve forecast skill, including Takens’ delay-coordinate maps (to recover information in the initial data lost through partial observations) and a directional dependence on the dynamical vector field generating the data. Mathematically, our approach is closely related to kernel methods for out-of-sample extension of functions, and we discuss alternative strategies based on the Nyström method and the multiscale Laplacian pyramids technique. We illustrate these techniques in applications to forecasting in a low-order deterministic model for atmospheric dynamics with chaotic metastability, and interannual-scale forecasting in the North Pacific sector of a comprehensive climate model. We find that forecasts based on kernel-weighted ensembles have significantly higher skill than the conventional approach following a single analog.

  9. Not All Analogies Are Created Equal: Associative and Categorical Analogy Processing following Brain Damage

    ERIC Educational Resources Information Center

    Schmidt, Gwenda L.; Cardillo, Eileen R.; Kranjec, Alexander; Lehet, Matthew; Widick, Page; Chatterjee, Anjan

    2012-01-01

    Current research on analogy processing assumes that different conceptual relations are treated similarly. However, just as words and concepts are related in distinct ways, different kinds of analogies may employ distinct types of relationships. An important distinction in how words are related is the difference between associative (dog-bone) and…

  10. Students' Pre- and Post-Teaching Analogical Reasoning when They Draw Their Analogies

    ERIC Educational Resources Information Center

    Mozzer, Nilmara Braga; Justi, Rosaria

    2012-01-01

    Analogies are parts of human thought. From them, we can acquire new knowledge or change that which already exists in our cognitive structure. In this sense, understanding the analogical reasoning process becomes an essential condition to understand how we learn. Despite the importance of such an understanding, there is no general agreement in…

  11. Analogy-Enhanced Instruction: Effects on Reasoning Skills in Science

    ERIC Educational Resources Information Center

    Remigio, Krisette B.; Yangco, Rosanelia T.; Espinosa, Allen A.

    2014-01-01

    The study examined the reasoning skills of first year high school students after learning general science concepts through analogies. Two intact heterogeneous sections were randomly assigned to Analogy-Enhanced Instruction (AEI) group and Non Analogy-Enhanced (NAEI) group. Various analogies were incorporated in the lessons of the AEI group for…

  12. The Importance of Explicitly Mapping Instructional Analogies in Science Education

    ERIC Educational Resources Information Center

    Asay, Loretta Johnson

    2013-01-01

    Analogies are ubiquitous during instruction in science classrooms, yet research about the effectiveness of using analogies has produced mixed results. An aspect seldom studied is a model of instruction when using analogies. The few existing models for instruction with analogies have not often been examined quantitatively. The Teaching With…

  13. Value and Limitations of Analogs in Teaching Mathematics.

    ERIC Educational Resources Information Center

    Halford, Graeme S.; Boulton-Lewis, Gillian M.

    Analogical reasoning is frequently used in acquisition of mathematical concepts. Concrete representations used to teach mathematics are essentially analogs of mathematical concepts, and it is argued that analogies enter into mathematical concept acquisition in numerous other ways as well. According to Gentner's theory, analogies entail a…

  14. Interaction of Chloramphenicol Tripeptide Analogs with Ribosomes.

    PubMed

    Tereshchenkov, A G; Shishkina, A V; Tashlitsky, V N; Korshunova, G A; Bogdanov, A A; Sumbatyan, N V

    2016-04-01

    Chloramphenicol amine peptide derivatives containing tripeptide fragments of regulatory "stop peptides" - MRL, IRA, IWP - were synthesized. The ability of the compounds to form ribosomal complexes was studied by displacement of the fluorescent erythromycin analog from its complex with E. coli ribosomes. It was found that peptide chloramphenicol analogs are able to bind to bacterial ribosomes. The dissociation constants were 4.3-10 µM, which is 100-fold lower than the corresponding values for chloramphenicol amine-ribosome complex. Interaction of the chloramphenicol peptide analogs with ribosomes was simulated by molecular docking, and the most probable contacts of "stop peptide" motifs with the elements of nascent peptide exit tunnel were identified. PMID:27293096

  15. Gravitoelectromagnetic analogy based on tidal tensors

    SciTech Connect

    Costa, L. Filipe O.; Herdeiro, Carlos A. R.

    2008-07-15

    We propose a new approach to a physical analogy between general relativity and electromagnetism, based on tidal tensors of both theories. Using this approach we write a covariant form for the gravitational analogues of the Maxwell equations, which makes transparent both the similarities and key differences between the two interactions. The following realizations of the analogy are given. The first one matches linearized gravitational tidal tensors to exact electromagnetic tidal tensors in Minkowski spacetime. The second one matches exact magnetic gravitational tidal tensors for ultrastationary metrics to exact magnetic tidal tensors of electromagnetism in curved spaces. In the third we show that our approach leads to a two-step exact derivation of Papapetrou's equation describing the force exerted on a spinning test particle. Analogous scalar invariants built from tidal tensors of both theories are also discussed.

  16. Biosynthesis of amphetamine analogs in plants.

    PubMed

    Hagel, Jillian M; Krizevski, Raz; Marsolais, Frédéric; Lewinsohn, Efraim; Facchini, Peter J

    2012-07-01

    Amphetamine analogs are produced by plants in the genus Ephedra and by Catha edulis, and include the widely used decongestants and appetite suppressants pseudoephedrine and ephedrine. A combination of yeast (Candida utilis or Saccharomyces cerevisiae) fermentation and subsequent chemical modification is used for the commercial production of these compounds. The availability of certain plant biosynthetic genes would facilitate the engineering of yeast strains capable of de novo pseudoephedrine and ephedrine biosynthesis. Chemical synthesis has yielded amphetamine analogs with myriad functional group substitutions and diverse pharmacological properties. The isolation of enzymes with the serendipitous capacity to accept novel substrates could allow the production of substituted amphetamines in synthetic biosystems. Here, we review the biology, biochemistry and biotechnological potential of amphetamine analogs in plants. PMID:22502775

  17. Polymeric nanogel formulations of nucleoside analogs

    PubMed Central

    Vinogradov, Serguei V

    2008-01-01

    Nanogels are colloidal microgel carriers that have been introduced recently as a prospective drug delivery system for nucleotide therapeutics. The crosslinked protonated polymer network of nanogels binds oppositely charged drug molecules, encapsulating them into submicron particles with a core-shell structure. The nanogel network also provides a suitable template for chemical engineering, surface modification and vectorisation. This review reveals recent attempts to develop novel drug formulations of nanogels with antiviral and antiproliferative nucleoside analogs in the active form of 5′-triphosphates; discusses structural approaches to the optimisation of nanogel properties, and; discusses the development of targeted nanogel drug formulations for systemic administration. Notably, nanogels can improve the CNS penetration of nucleoside analogs that are otherwise restricted from passing across the blood–brain barrier. The latest findings reviewed here demonstrate an efficient intracellular release of nucleoside analogs, encouraging further applications of nanogel carriers for targeted drug delivery. PMID:17184158

  18. Analog graphic display method and apparatus

    DOEpatents

    Kronberg, J.W.

    1991-08-13

    Disclosed are an apparatus and method for using an output device such as an LED to show the approximate analog level of a variable electrical signal wherein a modulating AC waveform is superimposed either on the signal or a reference voltage, both of which are then fed to a comparator which drives the output device. Said device flashes at a constant perceptible rate with a duty cycle which varies in response to variations in the level of the input signal. The human eye perceives these variations in duty cycle as analogous to variations in the level of the input signal. 21 figures.

  19. Space flight nutrition research: platforms and analogs.

    PubMed

    Smith, Scott M; Uchakin, Peter N; Tobin, Brian W

    2002-10-01

    Conducting research during actual or simulated weightlessness is a challenging endeavor, where even the simplest activities may present significant challenges. This article reviews some of the potential obstacles associated with performing research during space flight and offers brief descriptions of current and previous space research platforms and ground-based analogs, including those for human, animal, and cell-based research. This review is intended to highlight the main issues of space flight research analogs and leave the specifics for each physiologic system for the other papers in this section. PMID:12361789

  20. Parallel Analog-to-Digital Image Processor

    NASA Technical Reports Server (NTRS)

    Lokerson, D. C.

    1987-01-01

    Proposed integrated-circuit network of many identical units convert analog outputs of imaging arrays of x-ray or infrared detectors to digital outputs. Converter located near imaging detectors, within cryogenic detector package. Because converter output digital, lends itself well to multiplexing and to postprocessing for correction of gain and offset errors peculiar to each picture element and its sampling and conversion circuits. Analog-to-digital image processor is massively parallel system for processing data from array of photodetectors. System built as compact integrated circuit located near local plane. Buffer amplifier for each picture element has different offset.

  1. Associative Pattern Recognition In Analog VLSI Circuits

    NASA Technical Reports Server (NTRS)

    Tawel, Raoul

    1995-01-01

    Winner-take-all circuit selects best-match stored pattern. Prototype cascadable very-large-scale integrated (VLSI) circuit chips built and tested to demonstrate concept of electronic associative pattern recognition. Based on low-power, sub-threshold analog complementary oxide/semiconductor (CMOS) VLSI circuitry, each chip can store 128 sets (vectors) of 16 analog values (vector components), vectors representing known patterns as diverse as spectra, histograms, graphs, or brightnesses of pixels in images. Chips exploit parallel nature of vector quantization architecture to implement highly parallel processing in relatively simple computational cells. Through collective action, cells classify input pattern in fraction of microsecond while consuming power of few microwatts.

  2. Discrete analog computing with rotor-routers.

    PubMed

    Propp, James

    2010-09-01

    Rotor-routing is a procedure for routing tokens through a network that can implement certain kinds of computation. These computations are inherently asynchronous (the order in which tokens are routed makes no difference) and distributed (information is spread throughout the system). It is also possible to efficiently check that a computation has been carried out correctly in less time than the computation itself required, provided one has a certificate that can itself be computed by the rotor-router network. Rotor-router networks can be viewed as both discrete analogs of continuous linear systems and deterministic analogs of stochastic processes. PMID:20887076

  3. A quadratic analog-to-digital converter

    NASA Technical Reports Server (NTRS)

    Harrison, D. C.; Staples, M. H.

    1980-01-01

    An analog-to-digital converter with a square root transfer function has been developed for use with a pair of CCD imaging detectors in the White Light Coronagraph/X-ray XUV Telescope experiment to be flown as part of the Internal Solar Polar Mission. It is shown that in background-noise-limited instrumentation systems a quadratic analog-to-digital converter will allow a maximum dynamic range with a fixed number of data bits. Low power dissipation, moderately fast conversion time, and reliability are achieved in the proposed design using standard components and avoiding nonlinear elements.

  4. Analog graphic display method and apparatus

    DOEpatents

    Kronberg, James W.

    1991-01-01

    An apparatus and method for using an output device such as an LED to show the approximate analog level of a variable electrical signal wherein a modulating AC waveform is superimposed either on the signal or a reference voltage, both of which are then fed to a comparator which drives the output device. Said device flashes at a constant perceptible rate with a duty cycle which varies in response to variations in the level of the input signal. The human eye perceives these variations in duty cycle as analogous to variations in the level of the input signal.

  5. Synthetic heparin-binding factor analogs

    DOEpatents

    Pena, Louis A.; Zamora, Paul O.; Lin, Xinhua; Glass, John D.

    2010-04-20

    The invention provides synthetic heparin-binding growth factor analogs having at least one peptide chain, and preferably two peptide chains branched from a dipeptide branch moiety composed of two trifunctional amino acid residues, which peptide chain or chains bind a heparin-binding growth factor receptor and are covalently bound to a non-signaling peptide that includes a heparin-binding domain, preferably by a linker, which may be a hydrophobic linker. The synthetic heparin-binding growth factor analogs are useful as pharmaceutical agents, soluble biologics or as surface coatings for medical devices.

  6. Landauer bound for analog computing systems.

    PubMed

    Diamantini, M Cristina; Gammaitoni, Luca; Trugenberger, Carlo A

    2016-07-01

    By establishing a relation between information erasure and continuous phase transitions we generalize the Landauer bound to analog computing systems. The entropy production per degree of freedom during erasure of an analog variable (reset to standard value) is given by the logarithm of the configurational volume measured in units of its minimal quantum. As a consequence, every computation has to be carried on with a finite number of bits and infinite precision is forbidden by the fundamental laws of physics, since it would require an infinite amount of energy. PMID:27575108

  7. Space flight nutrition research: platforms and analogs

    NASA Technical Reports Server (NTRS)

    Smith, Scott M.; Uchakin, Peter N.; Tobin, Brian W.

    2002-01-01

    Conducting research during actual or simulated weightlessness is a challenging endeavor, where even the simplest activities may present significant challenges. This article reviews some of the potential obstacles associated with performing research during space flight and offers brief descriptions of current and previous space research platforms and ground-based analogs, including those for human, animal, and cell-based research. This review is intended to highlight the main issues of space flight research analogs and leave the specifics for each physiologic system for the other papers in this section.

  8. The GMO-Nanotech (Dis)Analogy?

    ERIC Educational Resources Information Center

    Sandler, Ronald; Kay, W. D.

    2006-01-01

    The genetically-modified-organism (GMO) experience has been prominent in motivating science, industry, and regulatory communities to address the social and ethical dimensions of nanotechnology. However, there are some significant problems with the GMO-nanotech analogy. First, it overstates the likelihood of a GMO-like backlash against…

  9. Invention through Form and Function Analogy

    ERIC Educational Resources Information Center

    Rule, Audrey C.

    2015-01-01

    "Invention through Form and Function Analogy" is an invention book for teachers and other leaders working with youth who are involving students in the invention process. The book consists of an introduction and set of nine learning cycle formatted lessons for teaching the principles of invention through the science and engineering design…

  10. Analog optical computing primitives in silicon photonics

    NASA Astrophysics Data System (ADS)

    Jiang, Yunshan; DeVore, Peter T. S.; Jalali, Bahram

    2016-03-01

    Optical computing accelerators may help alleviate bandwidth and power consumption bottlenecks in electronics. We show an approach to implementing logarithmic-type analog co-processors in silicon photonics and use it to perform the exponentiation operation. The function is realized by exploiting nonlinear-absorption-enhanced Raman amplification saturation in a silicon waveguide.

  11. New mitomycin analogs produced by directed biosynthesis.

    PubMed

    Claridge, C A; Bush, J A; Doyle, T W; Nettleton, D E; Moseley, J E; Kimball, D; Kammer, M F; Veitch, J

    1986-03-01

    When the normal fermentation medium for the production of mitomycin C with Streptomyces caespitosus is supplemented with a number of primary amines, two new types of mitomycin analogs described as Type I and Type II are produced. Type I analogs are related to mitomycin C with the amine substitution at position C7 on the mitosane ring. Type II analogs also contain the same substitutions at C7 but the conformation of the mitosane ring is related to mitomycin B having an OH at positions C9a and a methyl substituted aziridine. The products obtained from the supplementation of the medium with methylamine, ethylamine, propylamine, propargylamine and 2-methylallylamine were isolated and characterized. In all cases the Type I analogs are more active in a prophage induction test and against L1210 lymphatic leukemia in mice. A number of other amines have been tested and shown to yield new products that have not yet been isolated. No secondary amines are incorporated. PMID:3700245

  12. Presence, Analogy, and "Earth in the Balance."

    ERIC Educational Resources Information Center

    Murphy, John M.

    1994-01-01

    Uses vice president Albert Gore Jr.'s book "Earth in the Balance" as a case study to examine the relationship between analogy and "presence." Argues that presence is a flexible critical construct allowing for examination of the relationship between the style, substance, and structure of arguments. Explores relationships between C. Perelman and the…

  13. A Mechanical Analogy for Ohm's Law.

    ERIC Educational Resources Information Center

    do Couto Tavares, Milton; And Others

    1991-01-01

    A mechanical analogy between the microscopic motion of a charged carrier in an ordinary resistor and the macroscopic motion of a ball falling along a slanted board covered with a lattice of nails is introduced. The Drude model is also introduced to include the case of inelastic collisions. Computer simulation of the motion is described. (KR)

  14. (-)-Botryodiplodin, A Unique Ribose Analog Toxin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many toxins owe their mechanisms of action to being structural analogs of essential metabolites, messengers or structural components. Examples range from tubo-curare to penicillin. Ribose plays a unique role in the metabolism of living organisms, whether prokaryotes or eukaryotes. It and its deri...

  15. RF digital-to-analog converter

    DOEpatents

    Conway, P.H.; Yu, D.U.L.

    1995-02-28

    A digital-to-analog converter is disclosed for producing an RF output signal proportional to a digital input word of N bits from an RF reference input, N being an integer greater or equal to 2. The converter comprises a plurality of power splitters, power combiners and a plurality of mixers or RF switches connected in a predetermined configuration. 18 figs.

  16. Radiation Behavior of Analog Neural Network Chip

    NASA Technical Reports Server (NTRS)

    Langenbacher, H.; Zee, F.; Daud, T.; Thakoor, A.

    1996-01-01

    A neural network experiment conducted for the Space Technology Research Vehicle (STRV-1) 1-b launched in June 1994. Identical sets of analog feed-forward neural network chips was used to study and compare the effects of space and ground radiation on the chips. Three failure mechanisms are noted.

  17. Resistance Gene Analogs in Cherries (Prunus spp.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genetic studies have shown that NBS-LRR Resistance Gene Analogs (RGAs) tend to occur in clusters and often map to major resistances gene or QTL. The identification and use of specific RGAs as molecular markers among plant material displaying differential resistance phenotypes has the potential to di...

  18. The Lenz Vector and Orbital Analog Computers

    ERIC Educational Resources Information Center

    Harter, W. G.

    1976-01-01

    Describes a single geometrical diagram based on the Lenz vector which shows the qualitative and quantitative features of all three types of Coulomb orbits. Explains the use of a simple analog computer with an overhead projector to demonstrate many of these effects. (Author/CP)

  19. Plasma analog of particle-pair production

    SciTech Connect

    Tsidulko, Yu.A.; Berk, H.L.

    1996-09-01

    It is shown that the plasma axial shear flow instability satisfies the Klein-Gordon equation. The plasma instability is then shown to be analogous to spontaneous particle-pair production when a potential energy is present that is greater than twice the particle rest mass energy. Stability criteria can be inferred based on field theoretical conservation laws.

  20. Biological Analogs for Language Contact Situations

    ERIC Educational Resources Information Center

    Seliger, Herbert W.

    1977-01-01

    This article proposes that language contact can be best understood if the entire range of such situations from second language learning to evolution of dialects and creoles is studied within a framework analogical to the symbiosis of living organisms. Language contact is viewed in terms of dynamic evolutionary stages. (CHK)

  1. Multilateral Research Opportunities in Ground Analogs

    NASA Technical Reports Server (NTRS)

    Corbin, Barbara J.

    2015-01-01

    The global economy forces many nations to consider their national investments and make difficult decisions regarding their investment in future exploration. International collaboration provides an opportunity to leverage other nations' investments to meet common goals. The Humans In Space Community shares a common goal to enable safe, reliable, and productive human space exploration within and beyond Low Earth Orbit. Meeting this goal requires efficient use of limited resources and International capabilities. The International Space Station (ISS) is our primary platform to conduct microgravity research targeted at reducing human health and performance risks for exploration missions. Access to ISS resources, however, is becoming more and more constrained and will only be available through 2020 or 2024. NASA's Human Research Program (HRP) is actively pursuing methods to effectively utilize the ISS and appropriate ground analogs to understand and mitigate human health and performance risks prior to embarking on human exploration of deep space destinations. HRP developed a plan to use ground analogs of increasing fidelity to address questions related to exploration missions and is inviting International participation in these planned campaigns. Using established working groups and multilateral panels, the HRP is working with multiple Space Agencies to invite International participation in a series of 30- day missions that HRP will conduct in the US owned and operated Human Exploration Research Analog (HERA) during 2016. In addition, the HRP is negotiating access to Antarctic stations (both US and non-US), the German :envihab and Russian NEK facilities. These facilities provide unique capabilities to address critical research questions requiring longer duration simulation or isolation. We are negotiating release of international research opportunities to ensure a multilateral approach to future analog research campaigns, hoping to begin multilateral campaigns in the

  2. Not all analogies are created equal: Associative and categorical analogy processing following brain damage

    PubMed Central

    Schmidt, Gwenda L.; Cardillo, Eileen R.; Kranjec, Alexander; Lehet, Matthew; Widick, Page; Chatterjee, Anjan

    2012-01-01

    Current research on analogy processing assumes that different conceptual relations are treated similarly. However, just as words and concepts are related in distinct ways, different kinds of analogies may employ distinct types of relationships. An important distinction in how words are related is the difference between associative (dog-bone) and categorical (dog-cat) relations. To test the hypothesis that analogical mapping of different types of relations would have different neural instantiations, we tested patients with left and right hemisphere lesions on their ability to understand two types of analogies, ones expressing an associative relationship and others expressing a categorical relationship. Voxel-based lesion-symptom mapping (VLSM) and behavioral analyses revealed that associative analogies relied on a large left-lateralized language network while categorical analogies relied on both left and right hemispheres. The verbal nature of the task could account for the left hemisphere findings. We argue that categorical relations additionally rely on the right hemisphere because they are more difficult, abstract, and fragile; and contain more distant relationships. PMID:22402184

  3. Playing with a double-edged sword: Analogies in biochemistry

    NASA Astrophysics Data System (ADS)

    Orgill, Marykay

    Analogy pervades our everyday reasoning. No situation we encounter is exactly like a situation we have encountered previously, and our ability to learn and survive in the world is based on our ability to find similarities between past and present situations and use the knowledge we have gained from past situations to manage current situations. Analogies can be powerful teaching tools because they can make new material intelligible to students by comparing it to material that is already familiar. It is clear, though, that not all analogies are good and that not all good analogies are useful to all students. In this study, I have used textbook analysis, classroom observations, student interviews and instructor interviews to determine the role that analogies play in biochemistry learning. Analogies are an important teaching technique in biochemistry classes, being used more often in both biochemistry classes and textbooks than they are in high school chemistry classes and textbooks. Most biochemistry students like, pay particular attention to, and remember the analogies their instructors provide; and they use these analogies to understand, visualize, and recall information from class. Even though students like and use analogies, they do not understand what analogies are or the mechanism by which they improve learning. For the students, analogies are simply any teaching technique that eases understanding, visualization, or recall. Instructors, on the other hand, have a good understanding of what analogies are and of how they should be presented in class; but they do not use analogies as effectively as they should. They do not plan, explain or identify the limitations of the analogies they use in class. However, regardless of how effectively instructors present analogies in class, this study indicates that, in general, analogies are useful in promoting understanding, visualization, recall, and motivation in biochemistry students at all levels. They would be even more

  4. Observing spin optodynamical analog of cavity optomechanics

    NASA Astrophysics Data System (ADS)

    Gerber, Justin; Kohler, Jonathan; Spethmann, Nicolas; Schreppler, Sydney; Stamper-Kurn, Dan

    2016-05-01

    Cavity Optomechanics has been realized in many diverse systems and led to many interesting results such as ponderomotive squeezing of light, beyond-SQL measurement sensitivity, and squeezing of mechanical oscillators. Optical cavities also allow sensitive measurements of the spin of an atomic ensemble. It has been proposed to utilize this sensitivity to realize an analog of optomechanics by measuring the precession of small excitations of a spin-oscillator around a transverse magnetic field. I will present our recent work in which we realize optomechanical analogs in our system such as cavity-assisted cooling and amplification and optical spring shifts. In addition, the presence of a high-energy `ground state' of the spin oscillator allows the realization of an effective negative mass oscillator which is demonstrated by an inverted sideband asymmetry. In our ongoing work we attempt to realize coherent quantum noise cancelation by coupling spin oscillation with mechanical oscillation.

  5. A new program on digitizing analog seismograms

    NASA Astrophysics Data System (ADS)

    Wang, Maofa; Jiang, Qigang; Liu, Qingjie; Huang, Meng

    2016-08-01

    Historical seismograms contain a great variety of useful information which can be used in the study of earthquakes. It is necessary for researchers to digitize analog records and extract the information just as modern computing analysis requires. Firstly, an algorithm based on color scene filed method is presented in order to digitize analog seismograms. Secondly, an interactive software program using C# has been developed to digitize seismogram traces from raster files quickly and accurately. The program can deal with gray-scale images stored in a suitable file format and it offers two different methods: manual digitization and automatic digitization. The test result of the program shows that the methods presented in this paper can lead to good performance.

  6. Analog Computation by DNA Strand Displacement Circuits.

    PubMed

    Song, Tianqi; Garg, Sudhanshu; Mokhtar, Reem; Bui, Hieu; Reif, John

    2016-08-19

    DNA circuits have been widely used to develop biological computing devices because of their high programmability and versatility. Here, we propose an architecture for the systematic construction of DNA circuits for analog computation based on DNA strand displacement. The elementary gates in our architecture include addition, subtraction, and multiplication gates. The input and output of these gates are analog, which means that they are directly represented by the concentrations of the input and output DNA strands, respectively, without requiring a threshold for converting to Boolean signals. We provide detailed domain designs and kinetic simulations of the gates to demonstrate their expected performance. On the basis of these gates, we describe how DNA circuits to compute polynomial functions of inputs can be built. Using Taylor Series and Newton Iteration methods, functions beyond the scope of polynomials can also be computed by DNA circuits built upon our architecture. PMID:27363950

  7. Parabolic flight as a spaceflight analog.

    PubMed

    Shelhamer, Mark

    2016-06-15

    Ground-based analog facilities have had wide use in mimicking some of the features of spaceflight in a more-controlled and less-expensive manner. One such analog is parabolic flight, in which an aircraft flies repeated parabolic trajectories that provide short-duration periods of free fall (0 g) alternating with high-g pullout or recovery phases. Parabolic flight is unique in being able to provide true 0 g in a ground-based facility. Accordingly, it lends itself well to the investigation of specific areas of human spaceflight that can benefit from this capability, which predominantly includes neurovestibular effects, but also others such as human factors, locomotion, and medical procedures. Applications to research in artificial gravity and to effects likely to occur in upcoming commercial suborbital flights are also possible. PMID:26796759

  8. Optimal neural computations require analog processors

    SciTech Connect

    Beiu, V.

    1998-12-31

    This paper discusses some of the limitations of hardware implementations of neural networks. The authors start by presenting neural structures and their biological inspirations, while mentioning the simplifications leading to artificial neural networks. Further, the focus will be on hardware imposed constraints. They will present recent results for three different alternatives of parallel implementations of neural networks: digital circuits, threshold gate circuits, and analog circuits. The area and the delay will be related to the neurons` fan-in and to the precision of their synaptic weights. The main conclusion is that hardware-efficient solutions require analog computations, and suggests the following two alternatives: (i) cope with the limitations imposed by silicon, by speeding up the computation of the elementary silicon neurons; (2) investigate solutions which would allow the use of the third dimension (e.g. using optical interconnections).

  9. Submarine Analogs to Venusian Pancake Domes

    NASA Technical Reports Server (NTRS)

    Bridges, Nathan T.

    1995-01-01

    The morphology and dimensions of the large diameter, steep-sided, flat-topped "pancake domes" on Venus make them unlike any type of terrestrial subaerial volcano. Comparisons between images of Hawaiian seamounts and pancake domes show similarities in shapes and secondary features. The morphometry of pancake domes is closer to that of Pacific seamounts than subaerial lava domes. Considering both morphology and morphometry, seamounts seem a better analog to the pancake domes. The control of volatile exsolution by pressure on Venus and the seafloor can cause lavas to have similar viscosities and densities, although the latter will be counteracted by high buoyancy underwater. However, analogous effects of the Venusian and seafloor alone are probably not sufficient to produce similar volcanoes. Rather, Venusian lavas of various compositions may behave like basalt on the seafloor if appropriate rates and modes of extrusion and planetary thermal structure are also considered.

  10. Biomedical sensor design using analog compressed sensing

    NASA Astrophysics Data System (ADS)

    Balouchestani, Mohammadreza; Krishnan, Sridhar

    2015-05-01

    The main drawback of current healthcare systems is the location-specific nature of the system due to the use of fixed/wired biomedical sensors. Since biomedical sensors are usually driven by a battery, power consumption is the most important factor determining the life of a biomedical sensor. They are also restricted by size, cost, and transmission capacity. Therefore, it is important to reduce the load of sampling by merging the sampling and compression steps to reduce the storage usage, transmission times, and power consumption in order to expand the current healthcare systems to Wireless Healthcare Systems (WHSs). In this work, we present an implementation of a low-power biomedical sensor using analog Compressed Sensing (CS) framework for sparse biomedical signals that addresses both the energy and telemetry bandwidth constraints of wearable and wireless Body-Area Networks (BANs). This architecture enables continuous data acquisition and compression of biomedical signals that are suitable for a variety of diagnostic and treatment purposes. At the transmitter side, an analog-CS framework is applied at the sensing step before Analog to Digital Converter (ADC) in order to generate the compressed version of the input analog bio-signal. At the receiver side, a reconstruction algorithm based on Restricted Isometry Property (RIP) condition is applied in order to reconstruct the original bio-signals form the compressed bio-signals with high probability and enough accuracy. We examine the proposed algorithm with healthy and neuropathy surface Electromyography (sEMG) signals. The proposed algorithm achieves a good level for Average Recognition Rate (ARR) at 93% and reconstruction accuracy at 98.9%. In addition, The proposed architecture reduces total computation time from 32 to 11.5 seconds at sampling-rate=29 % of Nyquist rate, Percentage Residual Difference (PRD)=26 %, Root Mean Squared Error (RMSE)=3 %.

  11. The 2012 Moon and Mars Analog Mission

    NASA Technical Reports Server (NTRS)

    Graham, Lee

    2014-01-01

    The 2012 Moon and Mars Analog Mission Activities (MMAMA) scientific investigations were completed on Mauna Kea volcano in Hawaii in July 2012. The investigations were conducted on the southeast flank of the Mauna Kea volcano at an elevation of approximately 11,500 ft. This area is known as "Apollo Valley" and is in an adjacent valley to the Very Large Baseline Array dish antenna.

  12. Survey of Evaluated Isobaric Analog States

    SciTech Connect

    MacCormick, M.

    2014-06-15

    Isobaric analog states (IAS) can be used to estimate the masses of members belonging to the same isospin multiplet. Experimental and estimated IAS have been used frequently within the Atomic Mass Evaluation (AME) in the past, but the associated set of evaluated masses have been published for the first time in AME2012 and NUBASE2012. In this paper the current trends of the isobaric multiplet mass equation (IMME) coefficients are shown. The T = 2 multiplet is used as a detailed illustration.

  13. Magnetic Analog Random-Access Memory

    NASA Technical Reports Server (NTRS)

    Katti, Romney R.; Wu, Jiin-Chuan; Stadler, Henry L.

    1991-01-01

    Proposed integrated, solid-state, analog random-access memory base on principle of magnetic writing and magnetoresistive reading. Current in writing conductor magnetizes storage layer. Remanent magnetization in storage layer penetrates readout layer and detected by magnetoresistive effect or Hall effect. Memory cells are part of integrated circuit including associated reading and writing transistors. Intended to provide high storage density and rapid access, nonvolatile, consumes little power, and relatively invulnerable to ionizing radiation.

  14. Analog Processor To Solve Optimization Problems

    NASA Technical Reports Server (NTRS)

    Duong, Tuan A.; Eberhardt, Silvio P.; Thakoor, Anil P.

    1993-01-01

    Proposed analog processor solves "traveling-salesman" problem, considered paradigm of global-optimization problems involving routing or allocation of resources. Includes electronic neural network and auxiliary circuitry based partly on concepts described in "Neural-Network Processor Would Allocate Resources" (NPO-17781) and "Neural Network Solves 'Traveling-Salesman' Problem" (NPO-17807). Processor based on highly parallel computing solves problem in significantly less time.

  15. Synthesis and biological evaluation of platensimycin analogs

    SciTech Connect

    Shen, Hong C.; Ding, Fa-Xiang; Singh, Sheo B.; Parthasarathy, Gopalakrishnan; Soisson, Stephen M.; Ha, Sookhee N.; Chen, Xun; Kodali, Srinivas; Wang, Jun; Dorso, Karen; Tata, James R.; Hammond, Milton L.; MacCoss, Malcolm; Colletti, Steven L.

    2009-07-23

    Platensimycin (1) displays antibacterial activity due to its inhibition of the elongation condensing enzyme (FabF), a novel mode of action that could potentially lead to a breakthrough in developing a new generation of antibiotics. The medicinal chemistry efforts were focused on the modification of the enone moiety of platensimycin and several analogs showed significant activity against FabF and possess antibacterial activity.

  16. Antimicrobial Activity of Novel Furanonaphthoquinone Analogs

    PubMed Central

    Nagata, Kumiko; Hirai, Kei-Ichi; Koyama, Junko; Wada, Yasunao; Tamura, Toshihide

    1998-01-01

    Analogs of furanonaphthoquinone (FNQ) from Tecoma ipe Mart had MICs ranging from 1.56 to 25 μg/ml against gram-positive bacteria. FNQ showed significantly lower MICs against methicillin-resistant Staphylococcus aureus than against methicillin-sensitive S. aureus. FNQ inhibited Helicobacter pylori with an MIC of 0.1 μg/ml. Fungi, including pathogenic species, were sensitive to FNQ with MICs similar to those of amphotericin B. PMID:9517956

  17. Analog optical computing primitives in silicon photonics.

    PubMed

    Jiang, Yunshan; DeVore, Peter T S; Jalali, Bahram

    2016-03-15

    Optical computing accelerators help alleviate bandwidth and power consumption bottlenecks in electronics. We show an approach to implementing logarithmic-type analog co-processors in silicon photonics and use it to perform the exponentiation operation and the recovery of a signal in the presence of multiplicative distortion. The function is realized by exploiting nonlinear-absorption-enhanced Raman amplification saturation in a silicon waveguide. PMID:26977687

  18. Periglacial and glacial analogs for Martian landforms

    NASA Technical Reports Server (NTRS)

    Rossbacher, Lisa A.

    1992-01-01

    The list of useful terrestrial analogs for Martian landforms has been expanded to include: features developed by desiccation processes; catastrophic flood features associated with boulder-sized materials; and sorted ground developed at a density boundary. Quantitative analytical techniques developed for physical geography have been adapted and applied to planetary studies, including: quantification of the patterns of polygonally fractured ground to describe pattern randomness independent of pattern size, with possible correlation to the mechanism of origin and quantification of the relative area of a geomorphic feature or region in comparison to planetary scale. Information about Martian geomorphology studied in this project was presented at professional meetings world-wide, at seven colleges and universities, in two interactive televised courses, and as part of two books. Overall, this project has expanded the understanding of the range of terrestrial analogs for Martian landforms, including identifying several new analogs. The processes that created these terrestrial features are characterized by both cold temperatures and low humidity, and therefore both freeze-thaw and desiccation processes are important. All these results support the conclusion that water has played a significant role in the geomorphic history of Mars.

  19. Periglacial and glacial analogs for Martian landforms

    NASA Astrophysics Data System (ADS)

    Rossbacher, Lisa A.

    1992-12-01

    The list of useful terrestrial analogs for Martian landforms has been expanded to include: features developed by desiccation processes; catastrophic flood features associated with boulder-sized materials; and sorted ground developed at a density boundary. Quantitative analytical techniques developed for physical geography have been adapted and applied to planetary studies, including: quantification of the patterns of polygonally fractured ground to describe pattern randomness independent of pattern size, with possible correlation to the mechanism of origin and quantification of the relative area of a geomorphic feature or region in comparison to planetary scale. Information about Martian geomorphology studied in this project was presented at professional meetings world-wide, at seven colleges and universities, in two interactive televised courses, and as part of two books. Overall, this project has expanded the understanding of the range of terrestrial analogs for Martian landforms, including identifying several new analogs. The processes that created these terrestrial features are characterized by both cold temperatures and low humidity, and therefore both freeze-thaw and desiccation processes are important. All these results support the conclusion that water has played a significant role in the geomorphic history of Mars.

  20. Multiphoton excitation of fluorescent DNA base analogs

    NASA Astrophysics Data System (ADS)

    Katilius, Evaldas; Woodbury, Neal W.

    2006-07-01

    Multiphoton excitation was used to investigate properties of the fluorescent DNA base analogs, 2-aminopurine (2AP) and 6-methylisoxanthopterin (6MI). 2-aminopurine, a fluorescent analog of adenine, was excited by three-photon absorption. Fluorescence correlation measurements were attempted to evaluate the feasibility of using three-photon excitation of 2AP for DNA-protein interaction studies. However, high excitation power and long integration times needed to acquire high signal-to-noise fluorescence correlation curves render three-photon excitation FCS of 2AP not very useful for studying DNA base dynamics. The fluorescence properties of 6-methylisoxanthopterin, a guanine analog, were investigated using two-photon excitation. The two-photon absorption cross-section of 6MI was estimated to be about 2.5×10-50 cm4s (2.5 GM units) at 700 nm. The two-photon excitation spectrum was measured in the spectral region from 700 to 780 nm; in this region the shape of the two-photon excitation spectrum is very similar to the shape of single-photon excitation spectrum in the near-UV spectral region. Two-photon excitation of 6MI is suitable for fluorescence correlation measurements. Such measurements can be used to study DNA base dynamics and DNA-protein interactions over a broad range of time scales.

  1. Automated D/3 to Visio Analog Diagrams

    Energy Science and Technology Software Center (ESTSC)

    2000-08-10

    ADVAD1 reads an ASCII file containing the D/3 DCS MDL input for analog points for a D/3 continuous database. It uses the information in the files to create a series of Visio files representing the structure of each analog chain, one drawing per Visio file. The actual drawing function is performed by Visio (requires Visio version 4.5+). The user can configure the program to select which fields in the database are shown on the diagrammore » and how the information is to be presented. This gives a visual representation of the structure of the analog chains, showing selected fields in a consistent manner. Updating documentation can be done easily and the automated approach eliminates human error in the cadding process. The program can also create the drawings far faster than a human operator is capable, able to create approximately 270 typical diagrams in about 8 minutes on a Pentium II 400 MHz PC. The program allows for multiple option sets to be saved to provide different settings (i.e., different fields, different field presentations, and /or different diagram layouts) for various scenarios or facilities on one workstation. Option sets may be exported from the Windows registry to allow duplication of settings on another workstation.« less

  2. Backtracking quantum trajectories with analog feedback

    NASA Astrophysics Data System (ADS)

    de Lange*, G.; Ristè*, D.; Tiggelman, M. J.; Eichler, C.; Tornberg, L.; Johansson, G.; Wallraff, A.; Schouten, R. N.; Dicarlo, L.

    2014-03-01

    Circuit quantum electrodynamics offers a nearly ideal platform for the fundamental study of continuous quantum measurement. A nondemolition measurement of a superconducting qubit can be performed via homodyne detection of microwave transmission through a dispersively coupled cavity. By boosting the homodyne signal with a nearly noiseless phase-sensitive parametric amplifier, we experimentally show that a form of measurement backaction, consisting of stochastic quantum phase kicks on the measured qubit, is highly correlated with the fluctuations in the continuous homodyne record. We demonstrate a real-time analog feedback scheme that counteracts these phase kicks and thereby reduces measurement-induced dephasing. We develop a numerical optimization technique to overcome the bandwidth limitations of the amplification chain and provide a theoretical model for the optimization result. A quantum efficiency of 50% is extracted for the complete analog feedback loop. Finally, we discuss the integration of this analog feedback technique to improve performance in our recent demonstration of entanglement by dispersive parity measurement. *equal contribution. Research funded by NWO and the EU projects SOLID and SCALEQIT.

  3. Clinical utility of insulin and insulin analogs

    PubMed Central

    Sanlioglu, Ahter D.; Altunbas, Hasan Ali; Balci, Mustafa Kemal; Griffith, Thomas S.; Sanlioglu, Salih

    2013-01-01

    Diabetes is a pandemic disease characterized by autoimmune, genetic and metabolic abnormalities. While insulin deficiency manifested as hyperglycemia is a common sequel of both Type-1 and Type-2 diabetes (T1DM and T2DM), it does not result from a single genetic defect—rather insulin deficiency results from the functional loss of pancreatic β cells due to multifactorial mechanisms. Since pancreatic β cells of patients with T1DM are destroyed by autoimmune reaction, these patients require daily insulin injections. Insulin resistance followed by β cell dysfunction and β cell loss is the characteristics of T2DM. Therefore, most patients with T2DM will require insulin treatment due to eventual loss of insulin secretion. Despite the evidence of early insulin treatment lowering macrovascular (coronary artery disease, peripheral arterial disease and stroke) and microvascular (diabetic nephropathy, neuropathy and retinopathy) complications of T2DM, controversy exists among physicians on how to initiate and intensify insulin therapy. The slow acting nature of regular human insulin makes its use ineffective in counteracting postprandial hyperglycemia. Instead, recombinant insulin analogs have been generated with a variable degree of specificity and action. Due to the metabolic variability among individuals, optimum blood glucose management is a formidable task to accomplish despite the presence of novel insulin analogs. In this article, we present a recent update on insulin analog structure and function with an overview of the evidence on the various insulin regimens clinically used to treat diabetes. PMID:23584214

  4. Nonlinear feedback reduces analog-to-digital converter error

    NASA Technical Reports Server (NTRS)

    Munoz, R. M.

    1965-01-01

    Nonlinear analog-to-digital converter measures the analog input level and continuously adjusts the digital readout scale sensitivity to effectively increase the accuracy. It is able to acquire more accurate low-level data.

  5. Mars Analog Simulations for Future Human Missions to Mars

    NASA Astrophysics Data System (ADS)

    Engler, S. T.; Binsted, K.

    2014-07-01

    The NASA funded HI-SEAS (Hawaii Space Exploration Analog and Simulation) is a planetary surface exploration analog site at ~8500 feet on the Mauna Loa side of the saddle area on the Big Island of Hawaii.

  6. Synthesis and biological evaluation of new jasplakinolide (jaspamide) analogs

    PubMed Central

    Ghosh, Arun K.; Dawson, Zachary L.; Moon, Deuk Kyu; Bai, Ruoli; Hamel, Ernest

    2010-01-01

    Synthesis and biological evaluation of jasplakinolide analogs are described. The synthesis of analogs utilized a diastereoselective syn-aldol reaction and an orthoester Claisen rearrangement as key steps. All synthetic analogs were evaluated for their ability to disrupt the actin cytoskeleton. Compounds 2, 3, and 4 essentially displayed similar activity to jasplakinolide. PMID:20678932

  7. Functional DNA: Teaching Infinite Series through Genetic Analogy

    ERIC Educational Resources Information Center

    Kowalski, R. Travis

    2011-01-01

    This article presents an extended analogy that connects infinite sequences and series to the science of genetics, by identifying power series as "DNA for a function." This analogy allows standard topics such as convergence tests or Taylor approximations to be recast in a "forensic" light as mathematical analogs of genetic concepts such as DNA…

  8. Can Pupils Use Taught Analogies for Electric Current?

    ERIC Educational Resources Information Center

    Black, David; Solomon, Joan

    1987-01-01

    Discusses the use of analogies and models for teaching about electric current. Reports on a study in which one group of students used analogies to learn about electric current and one did not. Results indicate that, in this case, analogies did not play a significant role in student understanding. (TW)

  9. Modern Communication: Exploring Physiological Transmission through Tech-Savvy Analogies

    ERIC Educational Resources Information Center

    Hollabaugh, Christopher R.; Milanick, Mark A.

    2014-01-01

    Analogies are often helpful for students to grasp key physiological concepts; sometimes the technical jargon makes the concept seem more complex than it actually is. In this article the authors provide several analogies for information transfer processes that sometimes confuse students. For an analogy to be useful, of course, it needs to be…

  10. When Reasoning Modifies Memory: Schematic Assimilation Triggered by Analogical Mapping

    ERIC Educational Resources Information Center

    Vendetti, Michael S.; Wu, Aaron; Rowshanshad, Ebi; Knowlton, Barbara J.; Holyoak, Keith J.

    2014-01-01

    Analogical mapping highlights shared relations that link 2 situations, potentially at the expense of information that does not fit the dominant pattern of correspondences. To investigate whether analogical mapping can alter subsequent recognition memory for features of a source analog, we performed 2 experiments with 4-term proportional analogies…

  11. Analogies in Medicine: Valuable for Learning, Reasoning, Remembering and Naming

    ERIC Educational Resources Information Center

    Pena, Gil Patrus; Andrade-Filho, Jose de Souza

    2010-01-01

    Analogies are important tools in human reasoning and learning, for resolving problems and providing arguments, and are extensively used in medicine. Analogy and similarity involve a structural alignment or mapping between domains. This cognitive mechanism can be used to make inferences and learn new abstractions. Through analogies, we try to…

  12. Interactive Optical Disc Systems: Part 1: Analog Storage.

    ERIC Educational Resources Information Center

    Hessler, David W.

    1984-01-01

    Details distinction between digital and analog data, advantages of analog storage, and optical disc use to store analog data. Configuration and potential of three levels of laser disc systems are explained. Selection of display devices for use with laser disc systems and accessing audio data are addressed. (Continued in next issue.) (EJS)

  13. Analogical Instruction in Statistics: Implications for Social Work Educators

    ERIC Educational Resources Information Center

    Thomas, Leela

    2008-01-01

    This paper examines the use of analogies in statistics instruction. Much has been written about the difficulty social work students have with statistics. To address this concern, Glisson and Fischer (1987) called for the use of analogies. Understanding of analogical problem solving has surged in the last few decades with the integration of…

  14. Anti-inflammatory effect of thalidomide dithiocarbamate and dithioate analogs.

    PubMed

    Talaat, Roba; El-Sayed, Waheba; Agwa, Hussein S; Gamal-Eldeen, Amira M; Moawia, Shaden; Zahran, Magdy A H

    2015-08-01

    Thalidomide has anti-inflammatory, immunomodulatory, and anti-angiogenic properties. It has been used to treat a variety of cancers and autoimmune diseases. This study aimed to characterize anti-inflammatory activities of novel thalidomide analogs by exploring their effects on splenocytes proliferation and macrophage functions and their antioxidant activity. MTT assay was used to assess the cytotoxic effect of thalidomide analogs against splenocytes. Tumor necrosis factor (TNF-α) and nuclear factor kappa B (NF-κB-P65) were determined by enzyme-linked immunosorbent assay (ELISA). Nitric oxide (NO) was estimated by colorimetric assay. Antioxidant activity was examined by ORAC assay. Our results demonstrated that thalidomide dithioate analog 2 and thalidomide dithiocarbamate analog 4 produced a slight increase in splenocyte proliferation compared with thalidomide. Thalidomide dithiocarbamate analog 1 is a potent inhibitor of TNF-α production, whereas thalidomide dithiocarbamate analog 5 is a potent inhibitor of both TNF-α and NO. Analog 2 has a pronounced inhibitory effect on NF-κB-P65 production level. All thalidomide analogs showed prooxidant activity against hydroxyl (OH) radical. Analog 1 and thalidomide dithioate analog 3 have prooxidant activity against peroxyl (ROO) radical in relation to thalidomide. On the other hand, analog 4 has a potent scavenging capacity against peroxyl (ROO) radical compared with thalidomide. Taken together, the results of this study suggest that thalidomide analogs might have valuable anti-inflammatory activities with more pronounced effect than thalidomide itself. PMID:26051520

  15. Using Analogies as an Experiential Learning Technique in Multicultural Education

    ERIC Educational Resources Information Center

    Suthakaran, V.; Filsinger, Keri; White, Brittany

    2013-01-01

    In this article the authors specifically address the use of narratives in the form of analogies as an experiential learning activity. The use of analogies as an experiential learning tool in multicultural education can be helpful in a number of ways. Analogies provide an alternative tool for processing multicultural topics with students who have…

  16. Cholesterol side chain analogs but not its ether analogs possess cholesterol-lowering activity.

    PubMed

    Lei, Lin; Wang, Xiaobo; Huang, Weihuan; Liu, Yuwei; Zheng, Fangrui; Ma, Ka Ying; Li, Yuk Man; Wang, Lijun; Man, Sun Wa; Zhang, Chengnan; Chen, Zhen-Yu

    2015-02-01

    Cholesterol analogs can be used to treat hypercholesterolemia. The present study was to test the effects of cholesteryl 3β-ethoxy (CE) and cholesteryl 3β-methoxy (CM) on plasma total cholesterol (TC) compared with that of β-sitosterol (SI) in hamsters fed a high cholesterol diet. CM and CE are the methoxy and ethoxy analogs of cholesterol while SI is an analog of cholesterol having an additional ethyl group on the side chain. Results showed that SI at a dose of 0.1% could effectively reduce plasma TC by 18%. The analysis of sterols in the plasma and liver did not detect the presence of SI, proving that it was poorly absorbed in the intestine. In contrast, both CE and CM had no effect on plasma TC. However, CE and CM were found to accumulate in both plasma and liver, indicating that they could be well absorbed in the intestine. It was therefore concluded that analogs having different side chains possessed plasma TC-lowering activity, while analogs or derivatives on the hydroxyl group had no hypocholesterolemic activity. PMID:25536519

  17. Multiple Analogies for Complex Concepts: Antidotes for Analogy-Induced Misconception in Advanced Knowledge Acquisition. Technical Report No. 439.

    ERIC Educational Resources Information Center

    Spiro, Rand J.; And Others

    This report argues that there exists a pervasive tendency for analogies to contribute to the development of entrenched misconceptions in the form of reducing complex new knowledge to the core of a source analogy. The report presents a taxonomy of ways that simple analogy induces conceptual error and an alternative approach involving integrated…

  18. Inviting Argument by Analogy: Analogical-Mapping-Based Comparison Activities as a Scaffold for Small-Group Argumentation

    ERIC Educational Resources Information Center

    Emig, Brandon R.; McDonald, Scott; Zembal-Saul, Carla; Strauss, Susan G.

    2014-01-01

    This study invited small groups to make several arguments by analogy about simple machines. Groups were first provided training on analogical (structure) mapping and were then invited to use analogical mapping as a scaffold to make arguments. In making these arguments, groups were asked to consider three simple machines: two machines that they had…

  19. Study to Allow Access to Pasireotide for Patients Benefiting From Pasireotide Treatment in a Novartis-sponsored Study.

    ClinicalTrials.gov

    2016-09-07

    Cushing's Disease,; Acromegaly,; Neuroendocrine Tumors,; Pituitary Tumors; Ectopic ACTH Secreting (EAS) Tumors,; Dumping Syndrome,; Prostate Cancer,; Melanoma Negative for bRAF,; Melanoma Negative for nRAS

  20. Foam analogy in charged colloidal crystals.

    PubMed

    Kung, William; Ziherl, P; Kamien, Randall D

    2002-05-01

    We model charged colloidal suspensions using an analogy with foams. We study the solid-solid phase transitions of these systems as a function of particle volume fraction and ionic strength. The screened-Coulomb interaction is replaced by an interaction between walls of the Voronoi cells around each particle. We fit the surface charge to reproduce the phase diagram for the charged suspension studied by Sirota et al. [Phys. Rev. Lett. 62, 1524 (1989)]. With this fit parameter we are able to calculate the elastic moduli of the system and find good agreement with the available data. PMID:12059512

  1. Analog/Digital System for Germanium Thermometer

    NASA Technical Reports Server (NTRS)

    Woodhouse, Christopher

    1988-01-01

    Electronic system containing analog and digital circuits makes high-precision, four-wire measurements of resistance of each germanium resistance thermometer (GRT) in array of devices, using alternating current (ac) of 1 micro-A. At end measurement interval, contents of negative register subtracted from positive one, resulting in very-narrow-band synchronous demodulation of carrier wave and suppression of out-of-band noise. Microprocessor free to perform other duties after measurement complete. Useful in noisy terrestrial environments encountered in factories.

  2. Bosonic analog of the Klein paradox

    SciTech Connect

    Wagner, R. E.; Ware, M. R.; Su, Q.; Grobe, R.

    2010-02-15

    The standard Klein paradox describes how an incoming electron scatters off a supercritical electrostatic barrier that is so strong that it can generate electron-positron pairs. This fermionic system has been widely discussed in textbooks to illustrate some of the discrepancies between quantum mechanical and quantum field theoretical descriptions for the pair creation process. We compare the fermionic dynamics with that of the corresponding bosonic system. We point out that the direct counterpart of the Pauli exclusion principle (the central mechanism to resolve the fermionic Klein paradox) is stimulated emission, which leads to the resolution of the analogous bosonic paradox.

  3. Analogy among microfluidics, micromechanics, and microelectronics.

    PubMed

    Li, Sheng-Shian; Cheng, Chao-Min

    2013-10-01

    We wish to illuminate the analogous link between microfluidic-based devices, and the already established pairing of micromechanics and microelectronics to create a triangular/three-way scientific relationship as a means of interlinking familial disciplines and accomplishing two primary goals: (1) to facilitate the modeling of multidisciplinary domains; and, (2) to enable us to co-simulate the entire system within a compact circuit simulator (e.g., Cadence or SPICE). A microfluidic channel-like structure embedded in a micro-electro-mechanical resonator via our proposed CMOS-MEMS technology is used to illustrate the connections among microfluidics, micromechanics, and microelectronics. PMID:23963526

  4. Analog synthesized fast-variable linear load

    NASA Technical Reports Server (NTRS)

    Niedra, Janis M.

    1991-01-01

    A several kilowatt power level, fast-variable linear resistor was synthesized by using analog components to control the conductance of power MOSFETs. Risetimes observed have been as short as 500 ns with respect to the control signal and 1 to 2 microseconds with respect to the power source voltage. A variant configuration of this load that dissipates a constant power set by a control signal is indicated. Replacement of the MOSFETs by static induction transistors (SITs) to increase power handling, speed and radiation hardness is discussed.

  5. Microstore: the Stanford analog memory unit

    SciTech Connect

    Walker, J.T.; Chae, S.I.; Shapiro, S.; Larsen, R.S.

    1984-11-01

    An NMOS device has been developed which provides high speed analog signal storage and readout for time expansion of transient signals. This device takes advantage of HMOS-1 VLSI technology to implement an array of 256 storage cells. Sequential samples of an input waveform can be taken every 5 ns while providing an effective sampling aperture time of less than 1 ns. The design signal-to-noise ratio is 1 part in 2000. Digital control circuitry is provided on the chip for controlling the read-in and read-out processes. A reference circuit is incorporated in the chip for first order compensation of leakage drifts, sampling pedestals, and temperature effects.

  6. Scalable analog wavefront sensor with subpixel resolution

    NASA Astrophysics Data System (ADS)

    Wilcox, Michael

    2006-06-01

    Standard Shack-Hartman wavefront sensors use a CCD element to sample position and distortion of a target or guide star. Digital sampling of the element and transfer to a memory space for subsequent computation adds significant temporal delay, thus, limiting the spatial frequency and scalability of the system as a wavefront sensor. A new approach to sampling uses information processing principles in an insect compound eye. Analog circuitry eliminates digital sampling and extends the useful range of the system to control a deformable mirror and make a faster, more capable wavefront sensor.

  7. High-speed analog achromatic intensity modulator.

    PubMed

    Stockley, J E; Sharp, G D; Doroski, D; Johnson, K M

    1994-05-15

    We report what is to our knowledge the first implementation of a broadband analog intensity modulator composed of two chiral smectic liquid-crystal half-wave retarders. A reflection-mode intensity modulator employing a single active device has also demonstrated achromatic transmission. A quantitative theory for chromatic compensation is presented. By optimum selection of liquid-crystal retardance and orientation, intensity transmission is uniform throughout the visible. The chiral smectic liquid-crystal devices used in the implementation are capable of switching in less than 20 micros. PMID:19844436

  8. Soviet Space Stations as Analogs, Second Edition

    NASA Technical Reports Server (NTRS)

    Bluth, B. J.; Helppie, Martha

    1986-01-01

    The available literature that discusses the various aspects of the Soviet Salyut 6 and Salyut 7 space staions are examined as related to human productivity. The methodology for this analog was a search of unclassified literature. Additional information was obtained in interviews with the cosmonauts and some Soviet space personnel. Topics include: general layout and design of the spacecraft system; cosmonauts role in maintenance and repair; general layout and design of the Mir complex; effects of the environment on personnel; information and computer systems; organization systems; personality systems; and physical conditin of the cosmonaut.

  9. ANALOG QUANTUM NEURON FOR FUNCTIONS APPROXIMATION

    SciTech Connect

    A. EZHOV; A. KHROMOV; G. BERMAN

    2001-05-01

    We describe a system able to perform universal stochastic approximations of continuous multivariable functions in both neuron-like and quantum manner. The implementation of this model in the form of multi-barrier multiple-silt system has been earlier proposed. For the simplified waveguide variant of this model it is proved, that the system can approximate any continuous function of many variables. This theorem is also applied to the 2-input quantum neural model analogical to the schemes developed for quantum control.

  10. Article for analog vector algebra computation.

    PubMed

    Mills, A P; Yurke, B; Platzman, P M

    1999-10-01

    We introduce the concept of an analog neural network represented by chemical operations performed on strands of DNA. This new type of DNA computing has the advantage that it should be fault tolerant and thus more immune to DNA hybridization errors than a Boolean DNA computer. We describe a particular set of DNA operations to effect the interconversion of electrical and DNA data and to represent the Hopfield associative memory and the feed-forward neural network of Rumelhart et al. We speculate that networks containing as many as 10(9) neurons might be feasible. PMID:10636042