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Sample records for gastrointestinal transit time

  1. Regional gastrointestinal transit times in severe ulcerative colitis.

    PubMed

    Haase, A M; Gregersen, T; Christensen, L A; Agnholt, J; Dahlerup, J F; Schlageter, V; Krogh, K

    2016-02-01

    Gastrointestinal (GI) dysmotility may present secondary to inflammatory bowel disease. The main aim of this study was to investigate GI motility in ulcerative colitis (UC) patients during severe disease activity. Twenty patients with severe UC were studied with a novel telemetric capsule system (3D-Transit) designed for minimally invasive, ambulatory assessment of total and regional GI transit times. Ten patients were available for follow-up during remission. Data were compared to those of 20 healthy subjects (HS). Total GI transit time was significantly longer in patients with severe UC (median 44.5 h [range 9.9-102.7 h]) than in HS (median 27.6 h [range 9.6-56.4 h]) (p = 0.032). Additionally, during severe UC, transit time was prolonged through the proximal colon (p = 0.003) and there were strong trends toward longer than normal small intestinal transit time (HS: median 4.9 h [range 3.4-8.3 h] vs severe UC patients: median 5.9 h [range 3.9-11.9 h]; p = 0.053) and colorectal transit times (HS: median 18.2 h [range 1.5-43.7] vs severe UC patients: median 34.9 h [range 0.4-90.9 h]; p = 0.056). Our data further indicate that total GI and colorectal transit times may be prolonged in UC during early remission. Total GI transit times are significantly prolonged during severe UC. © 2016 John Wiley & Sons Ltd.

  2. Gastrointestinal Transit Time in Parkinson's Disease Using a Magnetic Tracking System.

    PubMed

    Knudsen, Karoline; Haase, Anne-Mette; Fedorova, Tatyana D; Bekker, Anne Charlotte; Østergaard, Karen; Krogh, Klaus; Borghammer, Per

    2017-01-01

    Symptoms from the gastrointestinal tract are highly prevalent in Parkinson's disease (PD), but knowledge of the underlying pathology is incomplete and valid objective markers on regional gastrointestinal function are limited. The aims were to evaluate gastrointestinal transit time and motility in PD patients and controls. Twenty-two PD patients and 15 controls were included. Gastric-, small intestinal-, and caecum-ascending colonic transit times as well as colonic motility, defined as mass- and fast movements, were performed using the ambulatory 3D-Transit system. Gastrointestinal transit time with radio opaque markers, gastric emptying scintigraphy, and subjective non-motor symptoms were also evaluated. Using the 3D-Transit system, the patient group displayed significantly longer small intestinal- and caecum-ascending transit times (p = 0.030 and p = 0.0063). No between-group difference was seen in gastric transit time (p = 0.91). Time to first mass- and fast colonic movement were significantly increased in PD (p = 0.023 and p = 0.006). Radio opaque marker gastrointestinal transit time was significantly increased in the patient group (p < 0.0001), whereas no difference was seen in scintigraphic gastric emptying time (p = 0.68). Prevalence of constipation symptoms on the NMSQuest was 41% in PD and 7% in controls. Significantly increased small intestinal- and caecum-ascending 3D-Transit times were detected in PD patients. Also, time to first propagating colonic movement was increased. Radio opaque marker gastrointestinal transit time was significantly delayed, but no difference was seen in gastric transit time and gastric emptying time. The present findings highlight widespread intestinal involvement in PD increasing throughout the gastrointestinal tract.

  3. Proof of Concept: Design and Initial Evaluation of a Device to Measure Gastrointestinal Transit Time.

    PubMed

    Wagner, Robert H; Savir-Baruch, Bital; Halama, James R; Venu, Mukund; Gabriel, Medhat S; Bova, Davide

    2017-09-01

    Chronic constipation and gastrointestinal motility disorders constitute a large part of a gastroenterology practice and have a significant impact on a patient's quality of life and lifestyle. In most cases, medications are prescribed to alleviate symptoms without there being an objective measurement of response. Commonly used investigations of gastrointestinal transit times are currently limited to radiopaque markers or electronic capsules. Repeated use of these techniques is limited because of the radiation exposure and the significant cost of the devices. We present the proof of concept for a new device to measure gastrointestinal transit time using commonly available and inexpensive materials with only a small amount of radiotracer. Methods: We assembled gelatin capsules containing a (67)Ga-citrate-radiolabeled grain of rice embedded in paraffin for use as a point-source transit device. It was tested for stability in vitro and subsequently was given orally to 4 healthy volunteers and 10 patients with constipation or diarrhea. Imaging was performed at regular intervals until the device was excreted. Results: The device remained intact and visible as a point source in all subjects until excretion. When used along with a diary of bowel movement times and dates, the device could determine the total transit time. The device could be visualized either alone or in combination with a barium small-bowel follow-through study or a gastric emptying study. Conclusion: The use of a point-source transit device for the determination of gastrointestinal transit time is a feasible alternative to other methods. The device is inexpensive and easy to assemble, requires only a small amount of radiotracer, and remains inert throughout the gastrointestinal tract, allowing for accurate determination of gastrointestinal transit time. Further investigation of the device is required to establish optimum imaging parameters and reference values. Measurements of gastrointestinal transit time

  4. Magnet tracking allows assessment of regional gastrointestinal transit times in children

    PubMed Central

    Hedsund, Caroline; Joensson, Iben Moeller; Gregersen, Tine; Fynne, Lotte; Schlageter, Vincent; Krogh, Klaus

    2013-01-01

    Background Data on small intestinal transit time in healthy children are lacking, and normal values for gastric emptying and colonic transit time are sparse. Conventional methods, including radiopaque markers, scintigraphy, and PillCam™ involve radiation or require the child to swallow a large pill. The minimally invasive, radiation-free Motility Tracking System-1 (MTS-1) has been introduced for description of gastrointestinal motility in adults. The aim of the study was to evaluate the MTS-1 for assessment of gastrointestinal transit times and motility patterns in healthy children. Methods Twenty-one healthy children (nine girls), median age 10 (range 7–12) years were included. For evaluation with MTS-1, a small magnetic pill was ingested and tracked through the gastrointestinal tract by a matrix of 16 magnetic sensors placed behind a nonmagnetic bed. The children were investigated for 8 hours after swallowing the magnetic pill and again for 4 hours the following morning. After leaving the unit, each child came back after every bowel movement to determine if the pill had been expelled. Results Nineteen children could swallow the pill. Characteristic contraction patterns were identified for the stomach (three per minute), small intestine (9–11 per minute), and colon (4–5 per minute). Median total gastrointestinal transit time was 37.7 (range 9.5–95.8) hours, median gastric emptying time was 37 (range 2–142) minutes, median small intestinal transit time was 302 (range 164 to >454) minutes, and median colorectal transit time was 38.1 (range 5.6–90.0) hours. Conclusion MTS-1 allows minimally invasive evaluation of gastrointestinal motility in children. Use of the method is, however, restricted by the nonambulatory setup. PMID:24399881

  5. Effect of Laparoscopic-assisted Gastropexy on Gastrointestinal Transit Time in Dogs.

    PubMed

    Balsa, I M; Culp, W T N; Drobatz, K J; Johnson, E G; Mayhew, P D; Marks, S L

    2017-09-20

    Prophylactic gastropexy has been promoted as a means of preventing gastric volvulus during gastric dilatation and volvulus (GDV) syndrome. Little is known about the impact of gastropexy on gastrointestinal transit time. Laparoscopic-assisted gastropexy (LAG) will not alter gastrointestinal transit times when comparing gastric (GET), small and large bowel (SLBTT), and whole gut transit times (TTT) before and after surgery. 10 healthy client-owned large-breed dogs. Prospective clinical trial. Before surgery, all dogs underwent physical examination and diagnostic evaluation to ensure normal health status. Dogs were fed a prescription diet for 6 weeks before determination of gastrointestinal transit with a wireless motility capsule. LAG was then performed, and dogs were fed the diet for 6 additional weeks. Measurement of transit times was repeated 6 weeks after surgery. Ten dogs of various breeds at-risk for GDV were enrolled. No complications were encountered associated with surgery or capsule administration. There were no significant differences in GET 429 [306-1,370] versus 541 [326-1,298] (P = 0.80), SLBTT 1,243 [841-3,070] versus 1,540 [756-2,623] (P = 0.72), or TTT 1,971 [1,205-3,469] versus 1,792 [1,234-3,343] minutes (median, range) (P = 0.65) before and after LAG. An effect of LAG on gastrointestinal transit time was not identified, and wireless motility capsule can be safely administered in dogs after LAG. Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

  6. Regional Gastrointestinal Transit Times in Patients With Carcinoid Diarrhea: Assessment With the Novel 3D-Transit System.

    PubMed

    Gregersen, Tine; Haase, Anne-Mette; Schlageter, Vincent; Gronbaek, Henning; Krogh, Klaus

    2015-07-30

    The paucity of knowledge regarding gastrointestinal motility in patients with neuroendocrine tumors and carcinoid diarrhea re-stricts targeted treatment. 3D-Transit is a novel, minimally invasive, ambulatory method for description of gastrointestinal motility. The system has not yet been evaluated in any group of patients. We aimed to test the performance of 3D-Transit in patients with carcinoid diarrhea and to compare the patients' regional gastrointestinal transit times (GITT) and colonic motility patterns with those of healthy subjects. Fifteen healthy volunteers and seven patients with neuroendocrine tumor and at least 3 bowel movements per day were inves-tigated with 3D-Transit and standard radiopaque markers. Total GITT assessed with 3D-Transit and radiopaque markers were well correlated (Spearman's rho = 0.64, P = 0.002). Median total GITT was 12.5 (range: 8.5-47.2) hours in patients versus 25.1 (range: 13.1-142.3) hours in healthy (P = 0.007). There was no difference in gastric emptying (P = 0.778). Median small intestinal transit time was 3.8 (range: 1.4-5.5) hours in patients versus 4.4 (range: 1.8-7.2) hours in healthy subjects (P = 0.044). Median colorectal transit time was 5.2 (range: 2.9-40.1) hours in patients versus 18.1 (range: 5.0-134.0) hours in healthy subjects (P = 0.012). Median frequency of pansegmental co-lonic movements was 0.45 (range: 0.03-1.02) per hour in patients and 0.07 (range: 0-0.61) per hour in healthy subjects (P = 0.045). Three-dimensional Transit allows assessment of regional GITT in patients with diarrhea. Patients with carcinoid diarrhea have faster than normal gastrointestinal transit due to faster small intestinal and colorectal transit times. The latter is caused by an increased frequency of pansegmental colonic movements.

  7. Regional Gastrointestinal Transit Times in Patients With Carcinoid Diarrhea: Assessment With the Novel 3D-Transit System

    PubMed Central

    Gregersen, Tine; Haase, Anne-Mette; Schlageter, Vincent; Gronbaek, Henning; Krogh, Klaus

    2015-01-01

    Background/Aims The paucity of knowledge regarding gastrointestinal motility in patients with neuroendocrine tumors and carcinoid diarrhea restricts targeted treatment. 3D-Transit is a novel, minimally invasive, ambulatory method for description of gastrointestinal motility. The system has not yet been evaluated in any group of patients. We aimed to test the performance of 3D-Transit in patients with carcinoid diarrhea and to compare the patients’ regional gastrointestinal transit times (GITT) and colonic motility patterns with those of healthy subjects. Methods Fifteen healthy volunteers and seven patients with neuroendocrine tumor and at least 3 bowel movements per day were investigated with 3D-Transit and standard radiopaque markers. Results Total GITT assessed with 3D-Transit and radiopaque markers were well correlated (Spearman’s rho = 0.64, P = 0.002). Median total GITT was 12.5 (range: 8.5–47.2) hours in patients versus 25.1 (range: 13.1–142.3) hours in healthy (P = 0.007). There was no difference in gastric emptying (P = 0.778). Median small intestinal transit time was 3.8 (range: 1.4–5.5) hours in patients versus 4.4 (range: 1.8–7.2) hours in healthy subjects (P = 0.044). Median colorectal transit time was 5.2 (range: 2.9–40.1) hours in patients versus 18.1 (range: 5.0–134.0) hours in healthy subjects (P = 0.012). Median frequency of pansegmental colonic movements was 0.45 (range: 0.03–1.02) per hour in patients and 0.07 (range: 0–0.61) per hour in healthy subjects (P = 0.045). Conclusions Three-dimensional Transit allows assessment of regional GITT in patients with diarrhea. Patients with carcinoid diarrhea have faster than normal gastrointestinal transit due to faster small intestinal and colorectal transit times. The latter is caused by an increased frequency of pansegmental colonic movements. PMID:26130638

  8. Route selection for double-balloon endoscopy, based on capsule transit time, in obscure gastrointestinal bleeding.

    PubMed

    Nakamura, Masanao; Ohmiya, Naoki; Shirai, Osamu; Takenaka, Hiroyuki; Morishima, Kenji; Miyahara, Ryoji; Ando, Takafumi; Watanabe, Osamu; Kawashima, Hiroki; Itoh, Akihiro; Hirooka, Yoshiki; Goto, Hidemi

    2010-06-01

    Double-balloon endoscopy (DBE) utilizes both oral and anal routes. The proper selection of the initial route is important for more rapid management of obscure gastrointestinal bleeding (OGIB). The aim of this retrospective study was to clarify the accuracy of the transit time of video capsule endoscopy (VCE) to the lesion as a predictive indicator for the decision on the initial DBE route. Of 172 patients who underwent both DBE and VCE, 65 who were diagnosed with small-intestinal hemorrhagic lesions by both means were enrolled. The relation between VCE transit time to the lesion and the DBE route by which the lesion was discovered was analyzed, distinguishing between 46 complete and 19 incomplete VCEs. Among the 46 patients with a complete VCE, the transit time and position of the lesion were strongly correlated. The best cutoff values for route selection by the VCE transit time from capsule intake and from the duodenal bulb to the lesion, determined using a receiver operating characteristic (ROC) curve, were 60% and 50%, respectively, of the transit time to the cecum. At that point, the accuracy of route selection was 90% and 94%, respectively. Positions shown by VCE for ileal lesions tended to be more proximal than those shown by surgery. In the 19 patients with incomplete VCEs, the best cutoff for transit time was 180 min from the duodenal bulb. The VCE transit time was useful for determining the route for DBE in OGIB. This parameter was most accurate when the cutoff value for the selection was half of the small-bowel transit time in the complete VCE examination.

  9. Determination of Gastrointestinal Transit Times in Barred Owls ( Strix varia ) by Contrast Fluoroscopy.

    PubMed

    Doss, Grayson A; Williams, Jackie M; Mans, Christoph

    2017-06-01

    Contrast imaging studies are routinely performed in avian patients when an underlying abnormality of the gastrointestinal (GI) tract is suspected. Fluoroscopy offers several advantages over traditional radiography and can be performed in conscious animals with minimal stress and restraint. Although birds of prey are commonly encountered as patients, little is known about GI transit times and contrast imaging studies in these species, especially owls. Owls are commonly encountered in zoological, educational, and wildlife settings. In this study, 12 adult barred owls ( Strix varia ) were gavage fed a 30% weight-by-volume barium suspension (25 mL/kg body weight). Fluoroscopic exposures were recorded at 5, 15, 30, 60, 120, 180, 240, and 300 minutes after administration. Overall GI transit time and transit times of various GI organs were recorded. Median (interquartile range [IQR]) overall GI transit time was 60 minutes (IQR: 19-60 minutes) and ranged from 5-120 minutes. Ventricular and small intestinal contrast filling was rapid. Ventricular emptying was complete by a median of 60 minutes (IQR: 30-120 minutes; range: 30-240 minutes), whereas small intestinal emptying was not complete in 9/12 birds by 300 minutes. Median small intestinal contraction rate was 15 per minute (IQR: 13-16 minutes; range: 10-19 minutes). Median overall GI transit time in barred owls is more rapid than mean transit times reported for psittacine birds and red-tailed hawks ( Buteo jamaicensis ). Fluoroscopy is a safe, suitable method for investigating GI motility and transit in this species.

  10. Relationship between gastrointestinal transit time and anesthetic fasting protocols in the captive chimpanzee, Pan troglodytes.

    PubMed

    Ardente, A; Chinnadurai, S; De Voe, R; Stringer, E; Webb, T; Ireland, J; Saker, K

    2011-06-01

    Lengthy social separation and prolonged fasting time contribute to increased risks associated with anesthesia in captive primates. This study is an initial attempt to identify a safe pre-anesthetic fasting procedure by identifying gastric emptying time (GET) and gastrointestinal transit time (GTT) of captive chimpanzees, Pan troglodytes. Seven adult chimpanzees at the North Carolina Zoo immobilized for annual physical examinations were fed barium-impregnated polyethylene spheres to measure GET. Eleven animals were individually fed a color dye marker and fecal passage was observed to determine GTT. Gastric emptying time (GET) was approximated to be >3 hours but <16 hours. The mean GTT was 16.5 hours. This study indicates that a fasting time of 3 hours would allow for complete gastric emptying and could potentially replace the current overnight fast (≥16 hour) to help minimize complications associated with pre-anesthetic fasting in captive primates. © 2011 John Wiley & Sons A/S.

  11. Establishment of a protocol for determining gastrointestinal transit time in mice using barium and radiopaque markers.

    PubMed

    Myagmarjalbuu, Bolormaa; Moon, Myeong Ju; Heo, Suk Hee; Jeong, Seo In; Park, Jong-Seong; Jun, Jae Yeoul; Jeong, Yong Yeon; Kang, Heoung Keun

    2013-01-01

    The purpose of this study was to establish a minimally invasive and reproducible protocol for estimating the gastrointestinal (GI) transit time in mice using barium and radiopaque markers. Twenty 5- to 6-week-old Balb/C female mice weighing 19-21 g were used. The animals were divided into three groups: two groups that received loperamide and a control group. The control group (n = 10) animals were administered physiological saline (1.5 mL/kg) orally. The loperamide group I (n = 10) and group II (n = 10) animals were administered 5 mg/kg and 10 mg/kg loperamide orally, respectively. Thirty minutes after receiving the saline or loperamide, the mice was administered 80 µL of barium solution and six iron balls (0.5 mm) via the mouth and the upper esophagus by gavage, respectively. Afterwards, the mice were continuously monitored with fluoroscopic imaging in order to evaluate the swallowing of the barium solution and markers. Serial fluoroscopic images were obtained at 5- or 10-min intervals until all markers had been excreted from the anal canal. For analysis, the GI transit times were subdivided into intestinal transit times (ITTs) and colon transit times (CTTs). The mean ITT was significantly longer in the loperamide groups than in the control group (p < 0.05). The mean ITT in loperamide group II (174.5 ± 32.3) was significantly longer than in loperamide group I (133.2 ± 24.2 minute) (p < 0.05). The mean CTT was significantly longer in loperamide group II than in the control group (p < 0.05). Also, no animal succumbed to death after the experimental procedure. The protocol for our study using radiopaque markers and barium is reproducible and minimally invasive in determining the GI transit time of the mouse model.

  12. Establishment of a Protocol for Determining Gastrointestinal Transit Time in Mice Using Barium and Radiopaque Markers

    PubMed Central

    Myagmarjalbuu, Bolormaa; Moon, Myeong Ju; Heo, Suk Hee; Jeong, Seo In; Park, Jong-Seong; Jun, Jae Yeoul; Kang, Heoung Keun

    2013-01-01

    Objective The purpose of this study was to establish a minimally invasive and reproducible protocol for estimating the gastrointestinal (GI) transit time in mice using barium and radiopaque markers. Materials and Methods Twenty 5- to 6-week-old Balb/C female mice weighing 19-21 g were used. The animals were divided into three groups: two groups that received loperamide and a control group. The control group (n = 10) animals were administered physiological saline (1.5 mL/kg) orally. The loperamide group I (n = 10) and group II (n = 10) animals were administered 5 mg/kg and 10 mg/kg loperamide orally, respectively. Thirty minutes after receiving the saline or loperamide, the mice was administered 80 µL of barium solution and six iron balls (0.5 mm) via the mouth and the upper esophagus by gavage, respectively. Afterwards, the mice were continuously monitored with fluoroscopic imaging in order to evaluate the swallowing of the barium solution and markers. Serial fluoroscopic images were obtained at 5- or 10-min intervals until all markers had been excreted from the anal canal. For analysis, the GI transit times were subdivided into intestinal transit times (ITTs) and colon transit times (CTTs). Results The mean ITT was significantly longer in the loperamide groups than in the control group (p < 0.05). The mean ITT in loperamide group II (174.5 ± 32.3) was significantly longer than in loperamide group I (133.2 ± 24.2 minute) (p < 0.05). The mean CTT was significantly longer in loperamide group II than in the control group (p < 0.05). Also, no animal succumbed to death after the experimental procedure. Conclusion The protocol for our study using radiopaque markers and barium is reproducible and minimally invasive in determining the GI transit time of the mouse model. PMID:23323030

  13. Characterizing gastrointestinal transit time in four lemur species using barium-impregnated polyethylene spheres (BIPS).

    PubMed

    Campbell, J L; Williams, C V; Eisemann, J H

    2004-11-01

    Differences in dietary profiles and gastrointestinal (GI) morphologies observed across lemur species suggest that there may be variation in patterns of digesta flow through the GI tract related to the method of digesta processing. Using radio-opaque barium-impregnated polyethylene spheres (BIPS), we characterized such patterns in four lemur species: Varecia variegata (VV), Eulemur fulvus (EF), Propithecus verreauxi (PV), and Hapalemur griseus (HG) (n = 2 per species). After an initial radiograph was taken under light sedation, the animals were fed the BIPS together with a small meal. A combination of 30 small (1.5 mm) and 10 large (5 mm) BIPS was administered. Radiographs were then taken on a species-dependent basis up to 48 hr post-dosage. For small BIPS, the gastric transit time (GTT; time of first exit of BIPS from stomach) was 0.25-2 hr for VV, EF, and HG, and approximately 10 hr for PV. The oro-rectal transit time (ORTT; time of first appearance in the rectum) was < 2 hr for VV and EF, and 24.0 hr for PV and HG. The intestinal transit time (ITT, measured as ORTT - GTT) was < 1.5 hr for VV and EF, and approximately 14 hr and 22 hr for PV and HG, respectively. These data suggest that the GTT of digesta as measured with BIPS was rapid for VV, EF, and HG. For VV and EF, the ORTT and ITT were also rapid, while for HG they were much slower. PV was characterized by delayed GTT, and a more rapid ITT compared to HG. Thus, patterns of flow for PV and HG, despite similar ORTT, differed in that HG emptied BIPS more rapidly and ITT was slower. The flow of BIPS did not differ for VV and EF. These data reveal new information in addition to the total tract transit time, and complement existing knowledge regarding anatomy and diet.

  14. Gastrointestinal and segmental colonic transit times in patients with acute and chronic spinal cord lesions.

    PubMed

    Krogh, K; Mosdal, C; Laurberg, S

    2000-10-01

    Longitudinal study among patients with acute and chronic spinal cord injuries (SCI). To compare total gastrointestinal transit times (GITT) and segmental colorectal transit times (CTT) in SCI patients with acute and chronic lesions to those of healthy volunteers. Furthermore, to examine the impact of time elapsed since injury on GITT and CTT, and finally to compare the pattern of colorectal dysfunction in patients with supraconal versus conal/cauda equina lesions. Surgical Research Unit and Department of Neurosurgery, University Hospital of Aarhus, Denmark. Patients took 10 radioopaque markers on six consecutive days and an abdominal X-ray was taken on day 7. GITT and CTTs were computed from the number of markers in the entire colorectum and in each colorectal segment respectively. We studied 26 patients with acute spinal cord lesions (15 supraconal and 11 conal/cauda equina lesions; time since injury=11 - 24 days) and 18 patients were available for follow-up 6 - 14 months later. Results were compared to 24 healthy volunteers. In patients with acute supraconal or conal/cauda equina lesions GITT and CTTs of the ascending, transverse, and descending colon were significantly prolonged, but rectosigmoid transit time was only significantly prolonged in patients with conal/cauda equina lesions. In patients with chronic supraconal lesions GITT and CTTs of the transverse colon and the descending colon were significantly prolonged. In patients with chronic conal/cauda equina lesions GITT and CTT of the transverse, the descending colon and the rectosigmoid were significantly prolonged. Thus, supraconal SCI resulted in generalized colonic dysfunction whereas chronic conal/cauda equina lesions resulted in severe rectosigmoid dysfunction. SCI results in severely prolonged colonic transit times both in the acute and chronic phase. However, the type of colorectal dysfunction depends on the level of SCI.

  15. Effect of magnesium on gastrointestinal transit time in normal and diabetic rats: possible mechanism of action.

    PubMed

    Adewoye, E O; Ige, A O

    2012-12-01

    Many gastrointestinal complications in diabetes are connected to neurohumoral dysfunction resulting in abnormalities of intestinal motility, secretion and absorption. Minerals have been reported as essential cofactors for basic cellular reactions but there is dearth of information on effect of Magnesium on gastrointestinal transit time (GITT) and the mechanism of action. Sixty male albino Wistar rats (180 - 200g) were grouped into twelve of five animals each. Group 1 (control) received 0.2ml saline. Groups 2-6 were normal rats treated with magnesium sulphate (as magnesium) (500mg/kg), adrenaline (0.5mg/kg), magnesium (500mg/kg) and adrenaline (0.5mg/kg), prazosin (1mg/kg) and both magnesium (500mg/kg) and prazosin (1mg/kg) respectively. Groups 7 - 12 were diabetic rats treated as in groups 1- 6. Diabetes was induced intraperitoneally with alloxan (120mg/kg bwt). There was significant (p<0.05) reduction in GITT index in normal rats treated with magnesium, prazosin and combination of magnesium and prazosin compared with control. Treatment with adrenaline alone produced significant increase in GITT. However treatment with both magnesium and adrenaline produced significant reduction compared with control. This reduction in GITT was similar to that obtained in magnesium only and prazosin only treated groups. Diabetic groups showed significant reduction in GITT in all treated groups except the adrenaline only treated group which produced significant increase in GITT. The significant reduction in GITT produced by magnesium in both normal and diabetic animals was comparable to that produced by prazosin (an á-adrenoceptor antagonist) indicating that magnesium may be inhibiting gastrointestinal smooth muscle contraction through á-adrenoceptor antagonist pathway.

  16. A mechanism-based approach for absorption modeling: the Gastro-Intestinal Transit Time (GITT) model.

    PubMed

    Hénin, Emilie; Bergstrand, Martin; Standing, Joseph F; Karlsson, Mats O

    2012-06-01

    Absorption models used in the estimation of pharmacokinetic drug characteristics from plasma concentration data are generally empirical and simple, utilizing no prior information on gastro-intestinal (GI) transit patterns. Our aim was to develop and evaluate an estimation strategy based on a mechanism-based model for drug absorption, which takes into account the tablet movement through the GI transit. This work is an extension of a previous model utilizing tablet movement characteristics derived from magnetic marker monitoring (MMM) and pharmacokinetic data. The new approach, which replaces MMM data with a GI transit model, was evaluated in data sets where MMM data were available (felodipine) or not available (diclofenac). Pharmacokinetic profiles in both datasets were well described by the model according to goodness-of-fit plots. Visual predictive checks showed the model to give superior simulation properties compared with a standard empirical approach (first-order absorption rate + lag-time). This model represents a step towards an integrated mechanism-based NLME model, where the use of physiological knowledge and in vitro–in vivo correlation helps fully characterize PK and generate hypotheses for new formulations or specific populations.

  17. Assessment of the Variation Associated with Repeated Measurement of Gastrointestinal Transit Times and Assessment of the Effect of Oral Ranitidine on Gastrointestinal Transit Times Using a Wireless Motility Capsule System in Dogs

    PubMed Central

    Lidbury, Jonathan A.; Suchodolski, Jan S.; Ivanek, Renata; Steiner, Jörg M.

    2012-01-01

    This study aimed to evaluate the variation associated with repeated measurement of gastrointestinal (GI) transit times and the effect of oral ranitidine on GI transit times in healthy dogs using a wireless motility capsule (WMC) system. Eight privately owned healthy adult dogs were enrolled, and one developed diarrhea and was removed from the study. For the first 3 repetitions, each dog was fed a standard meal followed by oral administration of a WMC. For the 4th repetition, each dog was given ranitidine hydrochloride (75 mg PO every 12 hours) prior to and during assessment of GI transit times. Mean between-subject coefficients of variation for gastric emptying time (GET), small and large bowel transit time (SLBTT), and total transit time (TTT) were 26.9%, 32.3%, and 19.6%, respectively. Mean within-subject coefficients of variation for GET, SLBTT, and TTT were 9.3%, 19.6%, and 15.9%, respectively. Median GET, SLBTT, and TTT without ranitidine were 719, 1,636, and 2,735 minutes, respectively. Median GET, SLBTT, and TTT with ranitidine were 757, 1,227, and 2,083 minutes, respectively. No significant differences in GI transit times were found between any of the 4 repetitions. Under these experimental conditions, no significant effects of oral ranitidine on GI transit times were observed. PMID:22792515

  18. Whole gastrointestinal transit time is associated with clinical severity and nutritional status of HIV-infected children.

    PubMed

    Densupsoontorn, Narumon; Issaragraiseel, Patchaya; Thamonsiri, Nuchnoi; Wongarn, Renu; Jirapinyo, Pipop

    2009-07-01

    Malnutrition and malabsorption are common consequences in pediatric human immunodeficiency virus (HIV) infection. The gastrointestinal tract is a major site affected by HIV Rapid gastrointestinal transit time may contribute to malabsorption. To determine whether the whole gastrointestinal transit time (WGTT) correlates with disease stages or degrees of malnutrition in HIV-infected children. Forty HIV-seropositive children, at various stages of disease, and thirty seronegative age-matched controls, aged between 1 mo and 3 yr, were enrolled in the present study. The body weight, length, or height and the WGTT were assessed Then the WGTT of children in different stages of HIV disease and in different degrees of malnutrition were compared with those of the control group. The mean ages were 15.5 and 14.3 mo in HIV-infected and control groups respectively. A greater degree of malnutrition was found in HIV-infected children with more advances HIV clinical symptoms. Compared to controls, WGTT was most rapid in severely symptomatic acquired immunodeficiency syndrome (AIDS) patients (Category C) (14.32 +/- 3.88 versus 7.22 +/- 3.17 h; p < 0.01) but not in asymptomatic, mildly and moderately symptomatic children. Accelerated WGTT in HIV-infected children was also significantly associated with a higher degree of malnutrition. Malnutrition is clearly related to the progression ofHIV disease. Accelerated WGTT is associated with HIV seropositivity, severe clinical symptoms, and higher degrees of malnutrition.

  19. Radiographic anatomy and barium sulfate contrast transit time of the gastrointestinal tract of bearded dragons (Pogona vitticeps).

    PubMed

    Grosset, Claire; Daniaux, Lise; Guzman, David Sanchez-Migallon; Weber, Ernest Scott; Zwingenberger, Allison; Paul-Murphy, Joanne

    2014-01-01

    The positive contrast gastrointestinal study is a common non-invasive diagnostic technique that does not require anesthesia and enables good visualization of the digestive tract. Radiographic anatomy and reference intervals for gastrointestinal contrast transit time in inland bearded dragons (Pogona vitticeps) were established using seven animals administered 15 ml/kg of a 35% w/v suspension of barium by esophageal gavage. Dorso-ventral and lateral radiographic views were performed at 0, 15, 30 min, 1, 2, 4, 6, 8, 12 h, and then every 12 h up to 96 h after barium administration. Gastric emptying was complete at a median time of 10 h (range 4-24 h). Median jejunum and small intestinal emptying times were 1 h (range 30 min-2 h) and 29 h (range 24-48 h), respectively. Median transit time for cecum was 10 h (range 8-12 h). Median time for contrast to reach the colon was 31 h (range 12-72 h) after administration. Results were compared to those obtained in other reptilian species. This technique appeared safe in fasted bearded dragons and would be clinically applicable in other lizard species.

  20. [Effects of various prokinetic drugs on gastrointestinal transit times in patients with progressive systemic scleroderma].

    PubMed

    Folwaczny, C; Läritz, M; Meurer, M; Endres, S P; König, A; Schindlbeck, N

    1997-10-01

    The intestine is involved in about half of the cases with progressive-systemic sclerosis. Intestinal transit disturbances which are caused by neuropathy of the enteric nerve system occur frequently. However, upto-date only few studies which determined the effect of prokinetic drugs exist. Patients with intestinal involvement caused by progressive-systemic sclerosis were treated with the prokinetic drugs cisapride (20 mg, TID; n = 9), erythromycin (250 mg, TID; n = 7) and octreotide (50 micrograms s. c., at night time; n = 5) over a period of four weeks. At study entry and after each treatment period the transit times through the stomach, small and large intestine were evaluated by use of the metal-detector test. Gastric emptying was only accelerated by erythromycin (42 +/- 3 min vs. 54 +/- 6 min; p = 0.0422), whereas treatment with cisapride and octreotide did not result in significant changes (48 +/- 4 min; p = 0.3743 and 44 +/- 4 min; p = 0.1975; resp.). Small intestinal transit times were not altered significantly by cisapride (108 +/- 15 min vs. 108 +/- 9 min; p = 0.2733), crythromycin (92 +/- 8 min; p = 0.0707) or octreotide (106 +/- 12 min; p = 0.8927). Furthermore colonic transit was not fastened by none of the prokinetic agents (study entry: 68 +/- 12 h; cisapride: 88 +/- 12 h; p = 0.0569; erythromycin 77 +/- 14 h; p = 0.7349; octreotide 107 +/- 14 h; p = 0.8927). Four patients were withdrawn from the study because of diarrhea. Prokinetic drugs do not seem to have a major impact on intestinal transit times in patients with progressive-systemic sclerosis. The use of these drugs is limited because of frequent side effects.

  1. A portable method for assessing gastrointestinal motility by simultaneously measuring transit time and contraction frequency.

    PubMed

    Li, H; Yan, G

    2008-01-01

    To portably monitor the motility of the total GI tract, a method for assessing GI motility by simultaneously measuring transit time and contraction frequency is put forward. The portable monitoring system is composed of a swallowable telemetric capsule, a portable recorder, magnetizing coils deposited in vitro, and workstation for data processing. The transit time and contraction frequency of the GI tract are deduced by analysing the variation of the position and orientation angles of a telemetric capsule in time domain and frequency domain. AC electromagnetic localization method is used to determine the position and orientation of the telemetric capsule in vivo. In the paper, the localization model based on a quasi-static magnetic field, the method of monitoring GI motility and the set-up of the monitoring system are detailed. Then from static and dynamic experiments, the performances of the system including the accuracy and dynamic response are evaluated. Finally, the electromagnetic safety of the system is verified by simulating electromagnetic radiation to the human body.

  2. Evaluation of gastric emptying time, gastrointestinal transit time, sedation score, and nausea score associated with intravenous constant rate infusion of lidocaine hydrochloride in clinically normal dogs.

    PubMed

    Johnson, Rebecca A; Kierski, Katharine R; Jones, Brian G

    2017-05-01

    OBJECTIVE To quantify nausea and sedation scores, gastric emptying time, and gastrointestinal transit time after IV administration of a lidocaine hydrochloride bolus followed by a constant rate infusion (CRI) in clinically normal dogs. ANIMALS 6 Beagles. PROCEDURES In a crossover study, dogs were fed thirty 1.5-mm barium-impregnated spheres (BIPS) and received a saline (0.9% NaCl) solution bolus (0.05 mL/kg) IV (time 0) followed by a CRI at 10 mL/h, a lidocaine bolus (1 mg/kg) IV followed by a CRI at 25 μg/kg/min, or a lidocaine bolus (1 mg/kg) IV followed by a CRI at 50 μg/kg/min; CRIs were for 12 hours. Nausea and sedation scores were assessed and abdominal radiographs obtained immediately after feeding of BIPS and every hour for 12 hours and again 16 hours after CRI start. Percentage of BIPSs in the small and large intestines, gastric emptying time, and gastrointestinal transit time were assessed. RESULTS Gastric emptying time did not differ significantly among treatments. Significantly more BIPS were in the large intestine 4 to 7 hours after treatment start for the 50-μg/kg/min treatment than for the other 2 treatments. Six hours after treatment start, significantly more BIPS were in the large intestine for the 25-μg/kg/min treatment than for the saline solution treatment. Higher sedation and nausea scores were associated with the 50-μg/kg/min CRI. CONCLUSIONS AND CLINICAL RELEVANCE In clinically normal dogs, lidocaine CRI did not significantly affect gastric emptying. However, gastrointestinal transit time was mildly decreased and sedation and nausea scores increased in dogs administered a lidocaine CRI at clinically used doses.

  3. Dietary A1 β-casein affects gastrointestinal transit time, dipeptidyl peptidase-4 activity, and inflammatory status relative to A2 β-casein in Wistar rats.

    PubMed

    Barnett, Matthew P G; McNabb, Warren C; Roy, Nicole C; Woodford, Keith B; Clarke, Andrew J

    2014-09-01

    We compared the gastrointestinal effects of milk-based diets in which the β-casein component was either the A1 or A2 type in male Wistar rats fed the experimental diets for 36 or 84 h. Gastrointestinal transit time was significantly greater in the A1 group, as measured by titanium dioxide recovery in the last 24 h of feeding. Co-administration of naloxone decreased gastrointestinal transit time in the A1 diet group but not in the A2 diet group. Colonic myeloperoxidase and jejunal dipeptidyl peptidase (DPP)-4 activities were greater in the A1 group than in the A2 group. Naloxone attenuated the increase in myeloperoxidase activity but not that in DPP-4 activity in the A1 group. Naloxone did not affect myeloperoxidase activity or DPP-4 activity in the A2 group. These results confirm that A1 β-casein consumption has direct effects on gastrointestinal function via opioid-dependent (gastrointestinal transit and myeloperoxidase activity) and opioid-independent (DPP-4 activity) pathways.

  4. Dose-response effect of Bifidobacterium lactis HN019 on whole gut transit time and functional gastrointestinal symptoms in adults

    PubMed Central

    Waller, Philip A; Gopal, Pramod K; Leyer, Gregory J; Ouwehand, Arthur C; Reifer, Cheryl; Stewart, Morgan E; Miller, Larry E

    2011-01-01

    Objective. To assess the impact of Bifidobacterium lactis HN019 supplementation on whole gut transit time (WGTT) and frequency of functional gastrointestinal (GI) symptoms in adults. Material and methods. We randomized 100 subjects (mean age: 44 years; 64% female) with functional GI symptoms to consume a proprietary probiotic strain, B. lactis HN019 (Fonterra Research Centre, Palmerston North, New Zealand), at daily doses of 17.2 billion colony forming units (CFU) (high dose; n = 33), 1.8 billion CFU (low dose; n = 33), or placebo (n = 34) for 14 days. The primary endpoint of WGTT was assessed by X-ray on days 0 and 14 and was preceded by consumption of radiopaque markers once a day for 6 days. The secondary endpoint of functional GI symptom frequency was recorded with a subject-reported numeric (1–100) scale before and after supplementation. Results. Decreases in mean WGTT over the 14-day study period were statistically significant in the high dose group (49 ± 30 to 21 ± 32 h, p < 0.001) and the low dose group (60 ± 33 to 41 ± 39 h, p = 0.01), but not in the placebo group (43 ± 31 to 44 ± 33 h). Time to excretion of all ingested markers was significantly shorter in the treatment groups versus placebo. Of the nine functional GI symptoms investigated, eight significantly decreased in frequency in the high dose group and seven decreased with low dose, while two decreased in the placebo group. No adverse events were reported in any group. Conclusions. Daily B. lactis HN019 supplementation is well tolerated, decreases WGTT in a dose-dependent manner, and reduces the frequency of functional GI symptoms in adults. PMID:21663486

  5. Dose-response effect of Bifidobacterium lactis HN019 on whole gut transit time and functional gastrointestinal symptoms in adults.

    PubMed

    Waller, Philip A; Gopal, Pramod K; Leyer, Gregory J; Ouwehand, Arthur C; Reifer, Cheryl; Stewart, Morgan E; Miller, Larry E

    2011-09-01

    To assess the impact of Bifidobacterium lactis HN019 supplementation on whole gut transit time (WGTT) and frequency of functional gastrointestinal (GI) symptoms in adults. We randomized 100 subjects (mean age: 44 years; 64% female) with functional GI symptoms to consume a proprietary probiotic strain, B. lactis HN019 (Fonterra Research Centre, Palmerston North, New Zealand), at daily doses of 17.2 billion colony forming units (CFU) (high dose; n = 33), 1.8 billion CFU (low dose; n = 33), or placebo (n = 34) for 14 days. The primary endpoint of WGTT was assessed by X-ray on days 0 and 14 and was preceded by consumption of radiopaque markers once a day for 6 days. The secondary endpoint of functional GI symptom frequency was recorded with a subject-reported numeric (1-100) scale before and after supplementation. Decreases in mean WGTT over the 14-day study period were statistically significant in the high dose group (49 ± 30 to 21 ± 32 h, p < 0.001) and the low dose group (60 ± 33 to 41 ± 39 h, p = 0.01), but not in the placebo group (43 ± 31 to 44 ± 33 h). Time to excretion of all ingested markers was significantly shorter in the treatment groups versus placebo. Of the nine functional GI symptoms investigated, eight significantly decreased in frequency in the high dose group and seven decreased with low dose, while two decreased in the placebo group. No adverse events were reported in any group. Daily B. lactis HN019 supplementation is well tolerated, decreases WGTT in a dose-dependent manner, and reduces the frequency of functional GI symptoms in adults.

  6. Type 1 diabetic patients with peripheral neuropathy have pan-enteric prolongation of gastrointestinal transit times and an altered caecal pH profile.

    PubMed

    Farmer, Adam D; Pedersen, Anne Grave; Brock, Birgitte; Jakobsen, Poul Erik; Karmisholt, Jesper; Mohammed, Sahar D; Scott, S Mark; Drewes, Asbjørn Mohr; Brock, Christina

    2017-04-01

    We hypothesised that type 1 diabetic patients with established diabetic sensorimotor polyneuropathy (DSPN) would have segmental and/or pan-enteric dysmotility in comparison to healthy age-matched controls. We aimed to investigate the co-relationships between gastrointestinal function, degree of DSPN and clinical symptoms. An observational comparison was made between 48 patients with DSPN (39 men, mean age 50 years, range 29-71 years), representing the baseline data of an ongoing clinical trial (representing a secondary analysis of baseline data collected from an ongoing double-blind randomised controlled trial investigating the neuroprotective effects of liraglutide) and 41 healthy participants (16 men, mean age 49 years, range 30-78) who underwent a standardised wireless motility capsule test to assess gastrointestinal transit. In patients, vibration thresholds, the Michigan Neuropathy Screening Instrument and Patient Assessment of Upper Gastrointestinal Symptom questionnaires were recorded. Compared with healthy controls, patients showed prolonged gastric emptying (299 ± 289 vs 179 ± 49 min; p = 0.01), small bowel transit (289 ± 107 vs 224 ± 63 min; p = 0.001), colonic transit (2140, interquartile range [IQR] 1149-2799 min vs 1087, IQR 882-1650 min; p = 0.0001) and whole-gut transit time (2721, IQR 1196-3541 min vs 1475 (IQR 1278-2214) min; p < 0.0001). Patients also showed an increased fall in pH across the ileocaecal junction (-1.8 ± 0.4 vs -1.3 ± 0.4 pH; p < 0.0001), which was associated with prolonged colonic transit (r = 0.3, p = 0.001). Multivariable regression, controlling for sex, disease duration and glycaemic control, demonstrated an association between whole-gut transit time and total GCSI (p = 0.02). Pan-enteric prolongation of gastrointestinal transit times and a more acidic caecal pH, which may represent heightened caecal fermentation, are present in patients with type 1 diabetes

  7. A Quantitative Review and Meta-models of the Variability and Factors Affecting Oral Drug Absorption-Part II: Gastrointestinal Transit Time.

    PubMed

    Abuhelwa, Ahmad Y; Foster, David J R; Upton, Richard N

    2016-09-01

    This study aimed to conduct a quantitative meta-analysis for the values of, and variability in, gastrointestinal (GI) transit times of non-disintegrating single-unit ("tablet") and multiple-unit ("pellets/multi-unit tablet") solid dosage forms, characterize the effect of food on the values and variability in these parameters and present quantitative meta-models of the distributions of GI transit times in the respective GI regions to help inform models of oral drug absorption. The literature was systemically reviewed for the values of, and the variability in, gastric, small intestinal and colonic transit times under fed and fasted conditions. Meta-analysis used the "metafor" package of the R language. Meta-models of GI transit were assumed to be log-normally distributed between the studied populations. Twenty-nine studies including 125 reported means and standard deviations were used in the meta-analysis. Caloric content of administered food increased variability and delayed the gastric transit of both pellets and tablets. Conversely, food caloric content reduced the variability but had no significant influence on the mean small intestinal transit time (SITT). Food had no significant effect on the transit time through the colon. The transit of pellets through the colon was significantly slower than that of single-unit tablets which is most likely related to their smaller size. GI transit times may influence the dissolution and absorption of oral drugs. The meta-models of GI transit times may be used as part of semi-physiological absorption models to characterize the influence of transit time on the dissolution, absorption and in vivo pharmacokinetic profiles of oral drugs.

  8. Evaluation of gastrointestinal tract transit times using barium-impregnated polyethylene spheres and barium sulfate suspension in a domestic pigeon (Columba livia) model.

    PubMed

    Bloch, Rebecca A; Cronin, Kimberly; Hoover, John P; Pechman, Robert D; Payton, Mark E

    2010-03-01

    Barium impregnated polyethylene spheres (BIPS) are used in small animal medicine as an alternative to barium sulfate for radiographic studies of the gastrointestinal tract. To determine the usefulness of BIPS as an alternative to barium suspension in measuring gastrointestinal (GI) transit time for avian species, ventrodorsal radiographs were used to follow the passage of BIPS and 30% barium sulfate suspension through the GI tracts of domestic pigeons (Columba livia). Gastrointestinal transit times of thirty 1.5-mm BIPS administered in moistened gelatin capsules and 30% barium sulfate suspension gavaged into the crop were compared in 6 pigeons. Although the barium suspension passed out of the GI tract of all pigeons within 24 hours, the 1.5-mm BIPS remained in the ventriculus for 368.0 +/- 176.8 hours and did not clear the GI tract for 424.0 +/- 204.6 hours. Although the times for passage of BIPS and 30% barium sulfate suspension from the crop into the ventriculus were not significantly different (P = .14), the times for passage of BIPS from the ventriculus into the large intestine-cloaca and for clearance from the GI tract of the pigeons were significantly longer (P < .001) than for the 30% barium sulfate suspension. From the results of this study, we conclude that BIPS are not useful for radiographically evaluating GI transit times in pigeons and are unlikely to be useful in other avian species that have a muscular ventriculus. BIPS may or may not be useful for evaluating GI transit times in species that lack a muscular ventriculus.

  9. The use of a wireless motility device (SmartPill®) for the measurement of gastrointestinal transit time after a dietary fibre intervention.

    PubMed

    Timm, Derek; Willis, Holly; Thomas, William; Sanders, Lisa; Boileau, Thomas; Slavin, Joanne

    2011-05-01

    Historically, measurement of gastrointestinal transit time has required collection and X-raying of faecal samples for up to 7 d after swallowing radio-opaque markers; a tedious, labour-intensive technique for both subjects and investigators. Recently, a wireless motility capsule (SmartPill®), which uses gut pH, pressure and temperature to measure transit time, has been developed. This device, however, has not been validated with dietary interventions. Therefore, we conducted a controlled cross-over trial to determine whether the device could detect a significant difference in transit time after ten healthy subjects (five men and five women) consumed 9 g of wheat bran (WB) or an equal volume, low-fibre control for 3 d. A paired t test was used to determine differences in transit times. Colonic transit time decreased by 10·8 (sd 6·6) h (P = 0·006) on the WB treatment. Whole-gut transit time also decreased by 8·9 (sd 5·4) h (P = 0·02) after the consumption of WB. Gastric emptying time and small-bowel transit time did not differ between treatments. Despite encouraging results, the present study had several limitations including short duration, lack of randomisation and unusable data due to delayed gastric emptying of the capsule. With minimal participant burden, the SmartPill technology appears to be a potentially useful tool for assessing transit time after a dietary intervention. This technology could be considered for digestive studies with novel fibres and other ingredients that are promoted for gut health.

  10. Implications of small-bowel transit time in the detection rate of capsule endoscopy: A multivariable multicenter study of patients with obscure gastrointestinal bleeding

    PubMed Central

    Girelli, Carlo Maria; Soncini, Marco; Rondonotti, Emanuele

    2017-01-01

    AIM To define the role of small-bowel transit time in the detection rate of significant small-bowel lesions. METHODS Small-bowel capsule endoscopy records, prospectively collected from 30 participating centers in the Lombardy Registry from October 2011 to December 2013, were included in the study if the clinical indication was obscure gastrointestinal bleeding and the capsule reached the cecum. Based on capsule findings, we created two groups: P2 (significant findings) and P0-1 (normal/negligible findings). Groups were compared for age, gender, small-bowel transit time, type of instrument, modality of capsule performance (outpatients vs inpatients), bowel cleanliness, and center volume. RESULTS We retrieved and scrutinized 1,433 out of 2,295 capsule endoscopy records (62.4%) fulfilling the inclusion criteria. Patients were 67 ± 15 years old, and 815 (57%) were males. In comparison with patients in the P0-1 group, those in the P2 group (n = 776, 54%) were older (P < 0.0001), had a longer small-bowel transit time (P = 0.0015), and were more frequently examined in low-volume centers (P < 0.001). Age and small-bowel transit time were correlated (P < 0.001), with age as the sole independent predictor on multivariable analysis. Findings of the P2 group were artero-venous malformations (54.5%), inflammatory (23.6%) and protruding (10.4%) lesions, and luminal blood (11.5%). CONCLUSION In this selected, prospectively collected cohort of small-bowel capsule endoscopy performed for obscure gastrointestinal bleeding, a longer small-bowel transit time was associated with a higher detection rate of significant lesions, along with age and a low center volume, with age serving as an independent predictor. PMID:28216977

  11. Implications of small-bowel transit time in the detection rate of capsule endoscopy: A multivariable multicenter study of patients with obscure gastrointestinal bleeding.

    PubMed

    Girelli, Carlo Maria; Soncini, Marco; Rondonotti, Emanuele

    2017-01-28

    To define the role of small-bowel transit time in the detection rate of significant small-bowel lesions. Small-bowel capsule endoscopy records, prospectively collected from 30 participating centers in the Lombardy Registry from October 2011 to December 2013, were included in the study if the clinical indication was obscure gastrointestinal bleeding and the capsule reached the cecum. Based on capsule findings, we created two groups: P2 (significant findings) and P0-1 (normal/negligible findings). Groups were compared for age, gender, small-bowel transit time, type of instrument, modality of capsule performance (outpatients vs inpatients), bowel cleanliness, and center volume. We retrieved and scrutinized 1,433 out of 2,295 capsule endoscopy records (62.4%) fulfilling the inclusion criteria. Patients were 67 ± 15 years old, and 815 (57%) were males. In comparison with patients in the P0-1 group, those in the P2 group (n = 776, 54%) were older (P < 0.0001), had a longer small-bowel transit time (P = 0.0015), and were more frequently examined in low-volume centers (P < 0.001). Age and small-bowel transit time were correlated (P < 0.001), with age as the sole independent predictor on multivariable analysis. Findings of the P2 group were artero-venous malformations (54.5%), inflammatory (23.6%) and protruding (10.4%) lesions, and luminal blood (11.5%). In this selected, prospectively collected cohort of small-bowel capsule endoscopy performed for obscure gastrointestinal bleeding, a longer small-bowel transit time was associated with a higher detection rate of significant lesions, along with age and a low center volume, with age serving as an independent predictor.

  12. Description of a dynamic in vitro model of the dog gastrointestinal tract and an evaluation of various transit times for protein and calcium.

    PubMed

    Smeets-Peeters, M J; Minekus, M; Havenaar, R; Schaafsma, G; Verstegen, M W

    1999-01-01

    In order to manufacture complete and balanced dog diets, it is important to know the nutrient requirements of dogs and the availability of these nutrients from food. As pet food manufacturers are restricted in their options for (invasive) animal studies, due to ethical constraints, it is important to have alternative methods for researching the effects of various dog diets. To simulate the gastrointestinal tract of the dog, the dynamic gastrointestinal tract model developed by Minekus et al. was further developed and modified in this study. The model consists of four compartments which simulate the stomach and small intestine (duodenum, jejunum and ileum). Each compartment is made of glass, with a flexible inner wall. This wall can be compressed by increasing the pressure of the surrounding water, mimicking the peristaltic movements and mixing seen in vivo. The model is computer-controlled to simulate physiological parameters such as pH, transit time and secretion of digestive juices, as derived from the literature. Gastric meal delivery and the effects of intestinal transit time on protein digestibility and availability for absorption of calcium from dog food were studied to evaluate the model. The gastric meal delivery of dry dog food was identical to a preset curve, which was based on in vivo data from healthy dogs. The emptying time for canned dog food was somewhat slower than the preset values, probably due to the viscosity of the meal. The differences between the preset values and the measured delivery were not significant. The digestibility of protein and the availability of calcium for absorption increased with a longer transit time. A significant difference was found between medium and slow transit times for the nitrogen content in the ileal delivery effluent and the jejunal dialysates (p < 0.05). The same trend was seen for calcium (not significant). The overall conclusion is that the model is a useful tool for mimicking the gastrointestinal tract of dogs

  13. Comparison of gastrointestinal transit times between chickens from D+ and D- genetic lines selected for divergent digestion efficiency.

    PubMed

    Rougière, N; Carré, B

    2010-11-01

    D+ (high digestion efficiency) and D- (low digestion efficiency) genetic chicken lines selected for divergent digestion efficiency were compared in this experiment. Gizzard functions were tested in terms of digesta mean retention time and reactions to high dilution of a corn diet with 15% coarse sunflower hulls. The corn standard (S) and high fibre (F) experimental diets were given from 9 days of age to chickens from both lines. Besides the measurements of growth efficiencies (9 to 20 days), digestibilities (20 to 23 days) and gut anatomy (0, 9, 29, 42 and 63 days), two digestive transit studies were performed at 9 and 29 days of age. For the transit studies, the S and F diets were labelled with 0.5% TiO2 and 1% Cr-mordanted sunflower hulls. These diets were fed ad libitum during 3 days, and then the birds were euthanized. The digestive contents were analysed for the determination of marker concentrations and mean retention times (MRTs) in digestive compartments (crop + oesophagus, proventriculus + gizzard, duodenum + jejunum, ileum, rectum + cloaca and caeca) were determined. D+ birds were confirmed as better digesters than D- birds during the growth period, in association with larger gizzard and pancreas, and lighter small intestine in D+ than in D-birds. The MRT in the proventriculus-gizzard system, higher in D+ than in D- birds, was a major factor associated with differences between D+ and D- birds regarding digestion efficiencies and gut anatomy. Diet dilution with fibres reduced differences in digestion efficiencies and proventriculus-gizzard MRT between lines. Differences in gut anatomy between lines tended to disappear after 8 weeks of age. In conclusion, this study showed that MRT in the proventriculus-gizzard system was a major factor associated with genotype differences between the D+ and D- genetic chicken lines selected for divergent digestion efficiency, with longer MRT found in D+ than in D- birds.

  14. The Impact of Opioid Treatment on Regional Gastrointestinal Transit

    PubMed Central

    Poulsen, Jakob L; Nilsson, Matias; Brock, Christina; Sandberg, Thomas H; Krogh, Klaus; Drewes, Asbjørn M

    2016-01-01

    Background/Aims To employ an experimental model of opioid-induced bowel dysfunction in healthy human volunteers, and evaluate the impact of opioid treatment compared to placebo on gastrointestinal (GI) symptoms and motility assessed by questionnaires and regional GI transit times using the 3-dimensional (3D)-Transit system. Methods Twenty-five healthy males were randomly assigned to oxycodone or placebo for 5 days in a double blind, crossover design. Adverse GI effects were measured with the bowel function index, gastrointestinal symptom rating scale, patient assessment of constipation symptom questionnaire, and Bristol stool form scale. Regional GI transit times were determined using the 3D-Transit system, and segmental transit times in the colon were determined using a custom Matlab® graphical user interface. Results GI symptom scores increased significantly across all applied GI questionnaires during opioid treatment. Oxycodone increased median total GI transit time from 22.2 to 43.9 hours (P < 0.001), segmental transit times in the cecum and ascending colon from 5.7 to 9.9 hours (P = 0.012), rectosigmoid colon transit from 2.7 to 9.0 hours (P = 0.044), and colorectal transit time from 18.6 to 38.6 hours (P = 0.001). No associations between questionnaire scores and segmental transit times were detected. Conclusions Self-assessed GI adverse effects and increased GI transit times in different segments were induced during oxycodone treatment. This detailed information about segmental changes in motility has great potential for future interventional head-to-head trials of different laxative regimes for prevention and treatment of constipation. PMID:26811503

  15. Relationship between gastrointestinal transit time and daily stool frequency in patients after Ileal J pouch-anal anastomosis for ulcerative colitis.

    PubMed

    Tomita, Ryouichi; Fujisaki, Shigeru; Tanjoh, Katsuhisa

    2004-01-01

    To investigate how the gastrointestinal transit function changes after ileal J pouch-anal anastomosis (IPAA) for ulcerative colitis (UC) and to study whether gastrointestinal transit time (GTT) has an influence on daily stool frequency, we investigated the relationship between GTT and stool frequency per day. Forty patients with UC who had undergone restorative proctocolectomy, with ileostomy closure at least 48 to 120 months (mean 96.3) previously, and who had no preoperative and postoperative complications were recruited. They were divided into two groups on the basis of their stool frequency: 26 patients had a stool frequency of less than 6 times per day (group A: 16 men, 10 women; aged 15 to 59 years old, average 36.6) and 14 patients had a stool frequency of 7 or more times per day (group B: 10 men, 4 women; 24 to 56 years old, average 40.9). The GTTs using a radiopaque marker were studied. Interviews concerning the defecation states were performed at the examination. High nocturnal stool frequency was significantly noted more in group B than in group A (P <0.001). All cases in group A and 12 cases in group B could discriminate flatus from feces, and there were significant differences between groups A and B (P <0.05). Feeling of stool remaining was significantly noted more in group B than in group A (P <0.01). Stool consistency in group A was harder than that in group B (P <0.001). Patients with soiling were significantly noted more in group B compared with those in group A (P <0.001). Incontinence was detected in only 2 cases in group B. Group A showed a better defecation state than group B. In the GTT study, the GTT was almost the same in groups A and B. The small bowel transit, pouch transit, and whole gut transit times in group B were faster than those of group A (P <0.001). Removal length of the terminal ileum in patients after IPAA: patients in group B (13.8 +/- 3.9 cm) had significantly more ileum removed compared with patients in group A (6.3 +/- 2

  16. Gastrointestinal pH and Transit Time Profiling in Healthy Volunteers Using the IntelliCap System Confirms Ileo-Colonic Release of ColoPulse Tablets

    PubMed Central

    Maurer, Jacoba M.; Schellekens, Reinout C. A.; van Rieke, Hèlen M.; Wanke, Christoph; Iordanov, Ventzeslav; Stellaard, Frans; Wutzke, Klaus D.; Dijkstra, Gerard; van der Zee, Margot; Woerdenbag, Herman J.; Frijlink, Henderik W.; Kosterink, Jos G. W.

    2015-01-01

    Introduction ColoPulse tablets are an innovative development in the field of oral dosage forms characterized by a distal ileum and colon-specific release. Previous studies in humans showed release in the ileo-colonic region, but the relationship between gastrointestinal pH and release was not experimentally proven in vivo. This information will complete the in vivo release-profile of ColoPulse tablets. Materials and Methods Release from ColoPulse tablets was studied in 16 healthy volunteers using the dual label isotope strategy. To determine gastrointestinal pH profiles and transit times the IntelliCap system was used. A ColoPulse tablet containing 13C-urea and an uncoated, immediate release tablet containing 15N2-urea were taken simultaneously followed by a standardized breakfast after three hours. Five minutes after intake of the tablets the IntelliCap capsule was swallowed and pH was measured until excretion in the feces. Breath and urine samples were collected for isotope analysis. Results Full analysis could be performed in 12 subjects. Median bioavailability of 13C -urea was 82% (95% CI 74–94%, range 61–114%). The median lag time (5% release of 13C) was 5:42 h (95% CI 5:18–6:18 h, range 2:36–6:36 h,) There was no statistically significant difference between lag time based on isotope signal and colon arrival time (CAT) based on pH (median 5:42 vs 5:31 h p = 0.903). In all subjects an intestinal pH value of 7.0 was reached before release of 13C from the ColoPulse tablet occurred. Discussion and Conclusions From the combined data from the IntelliCap system and the 13C -isotope signal it can be concluded that release from a ColoPulse tablet in vivo is not related to transit times but occurs in the ileo-colonic region after pH 7.0 is reached. This supports our earlier findings and confirms that the ColoPulse system is a promising delivery system for targeting the distal ileum and colon. Trial Registration ISRCTN Registry 18301880 PMID:26177019

  17. The Impact of Opioid Treatment on Regional Gastrointestinal Transit.

    PubMed

    Poulsen, Jakob L; Nilsson, Matias; Brock, Christina; Sandberg, Thomas H; Krogh, Klaus; Drewes, Asbjørn M

    2016-04-30

    To employ an experimental model of opioid-induced bowel dysfunction in healthy human volunteers, and evaluate the impact ofopioid treatment compared to placebo on gastrointestinal (GI) symptoms and motility assessed by questionnaires and regional GItransit times using the 3-dimensional (3D)-Transit system. Twenty-five healthy males were randomly assigned to oxycodone or placebo for 5 days in a double blind, crossover design. AdverseGI effects were measured with the bowel function index, gastrointestinal symptom rating scale, patient assessment of constipationsymptom questionnaire, and Bristol stool form scale. Regional GI transit times were determined using the 3D-Transit system, and segmental transit times in the colon were determined using a custom Matlab(®) graphical user interface. GI symptom scores increased significantly across all applied GI questionnaires during opioid treatment. Oxycodone increased median total GI transit time from 22.2 to 43.9 hours (P < 0.001), segmental transit times in the cecum and ascending colon from 5.7 to 9.9 hours (P = 0.012), rectosigmoid colon transit from 2.7 to 9.0 hours (P = 0.044), and colorectal transit time from 18.6 to 38.6 hours (P= 0.001). No associations between questionnaire scores and segmental transit times were detected. Self-assessed GI adverse effects and increased GI transit times in different segments were induced during oxycodone treatment. This detailed information about segmental changes in motility has great potential for future interventional head-to-head trials of different laxative regimes for prevention and treatment of constipation.

  18. Daily consumption of a synbiotic yogurt decreases energy intake but does not improve gastrointestinal transit time: a double-blind, randomized, crossover study in healthy adults

    PubMed Central

    2013-01-01

    Objective Probiotic and synbiotic products are widely marketed to healthy individuals, although potential benefits for these individuals are rarely studied. This study investigated the effect of daily consumption of a synbiotic yogurt on gastrointestinal (GI) function in a sample of healthy adults. Subjects/Methods In a randomized crossover double-blind study, 65 healthy adults consumed 200 g/day of yogurt with (synbiotic) or without (control) added probiotics (Bifidobacterium lactis Bb12, Lactobacillus acidophilus La5, Lactobacillus casei CRL431) and 4 g inulin for two 15-day treatment periods, each preceded by a 6-week washout period. GI transit time (GTT), duration of colour (DOC), GI symptoms and dietary intake were assessed and analyzed using repeated measures ANOVA, including PRE-treatment GTT as a covariate. Participants were grouped as short GTT (STT, n = 50, ≤32.7 h) or long GTT (LTT, n = 15, >32.7 h) based on their PRE-treatment GTT assessment. Results POST-treatment GTT and DOC were not different between synbiotic and control, and did not change from PRE-treatment, within the STT or LTT groups. There were no changes in GI symptom ratings, indicating that both yogurts were well tolerated. In STT, energy, fat and protein intakes were decreased from baseline with synbiotic (p = 0.055, p = 0.059 and p = 0.005, respectively) and dietary fibre intake was higher POST-treatment with synbiotic versus control (p = 0.0002). In LTT, decreases in energy and fat intakes with synbiotic were not significant (p = 0.14 and p = 0.18, respectively) and there were no differences in dietary fibre intake. Conclusion Consuming 200 g/day of synbiotic yogurt did not significantly alter GTT in healthy adults, but was well tolerated and helped to reduce overall energy intake. PMID:23787118

  19. A non-invasive method to evaluate gastrointestinal transit behavior in rat.

    PubMed

    Bove, Geoffrey M

    2015-01-01

    Many factors alter gastrointestinal transit. Animal models are useful for preclinical studies of gastrointestinal transit, but terminal methods do not allow later study, and stressful assessment methods will likely alter the transit of the animal. To overcome these factors, we developed a new method to assay rat total gastrointestinal transit. Standard plastic cages with their bottoms cut off were placed on wire mesh floors. Custom apparatuses were built to contain fecal pellets as they fell through the floors. Webcams connected to a computer running a security program were placed to image the pellets at regular intervals. Custom food was obtained with and without blue pigment. After habituating to the cages and the non-pigmented food, the pigmented food was administered. The duration to the appearance of the first pigmented pellet was determined by reviewing the photographs. This duration represents the complete gastrointestinal behavior, including feeding. We compared 24-hour fecal pellet counts using images to counts by visual inspection, and also made hourly counts. After establishing baseline transit times and hourly fecal pellet discharge, rats were given buprenorphine, known to alter gastrointestinal transit. Transit times and hourly discharge were obtained again and compared to the baselines. The methods were successful in determining transit times. Baseline measures were consistent between three groups of 8 rats. Visual and image-based counts were highly correlated. Transit times and hourly pellet discharge were reduced by buprenorphine. The described method offers a relatively simple, inexpensive, and non-invasive means to measure rat gastrointestinal behavior. The method has potential for any study where altered total gastrointestinal transit is an experimental concern. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Gastrointestinal Motility, Part 2: Small-Bowel and Colon Transit.

    PubMed

    Maurer, Alan H

    2016-03-01

    Because of the difficulty often encountered in deciding whether a patient's symptoms originate in the upper or lower gastrointestinal tract, gastrointestinal transit scintigraphy is a uniquely suited noninvasive, quantitative, and physiologic method of determining whether there is a motility disorder affecting the stomach, small bowel, or colon. Small-bowel and colon transit studies can be performed alone or together with gastric emptying studies after oral administration of an appropriately radiolabeled meal. It is hoped that newly published standards for performing these studies and the anticipated arrival of new Current Procedural Terminology codes in the United States for small-bowel and colon transit studies will increase their availability and use.

  1. Gastrointestinal Motility, Part 2: Small-Bowel and Colon Transit.

    PubMed

    Maurer, Alan H

    2015-09-01

    Because of the difficulty often encountered in deciding whether a patient's symptoms originate in the upper or lower gastrointestinal tract, gastrointestinal transit scintigraphy is a uniquely suited noninvasive, quantitative, and physiologic method of determining whether there is a motility disorder affecting the stomach, small bowel, or colon. Small-bowel and colon transit studies can be performed alone or together with gastric emptying studies after oral administration of an appropriately radiolabeled meal. It is hoped that newly published standards for performing these studies and the anticipated arrival of new Current Procedural Terminology codes in the United States for small-bowel and colon transit studies will increase their availability and use.

  2. Do gastrointestinal transit parameters influence the pharmacokinetics of gefitinib?

    PubMed

    Wilson, C G; O'Mahony, B; Connolly, S M; Cantarini, M V; Farmer, M R; Dickinson, P A; Smith, R P; Swaisland, H C

    2009-07-06

    The selective EGFR tyrosine kinase inhibitor, gefitinib has been shown to be active against certain human carcinomas. It had been noted that a proportion of volunteers consistently had lower gefitinib exposure following oral administration. The shape of the elimination profile in this subset was also different, showing a monophasic elimination pattern rather than the biphasic pattern observed in the majority of subjects. A gamma scintigraphic study was conducted to examine the relationship of gastrointestinal transit and drug absorption in a cohort of rapid clearance subjects (n=5) and normal profile volunteers (n=7). The fasted volunteer panel received a 250 mg gefitinib tablet labelled with [(111)In]-DTPA together with 240 mL [(99m)Tc]-labelled water. The rapid clearance cohorts were shown to have a faster mean gastric emptying T90 (37 min vs 74 min) and shorter small intestinal transit time (156 min vs 204 min), resulting in an earlier colonic arrival time (181 min vs 244 min). Mean plasma C(max) was lower (99.2 ng/mL vs 116 ng/mL) and AUC almost half in the rapid clearance group (2162+/-81 ngh/mL vs 4996+/-64 ngh/mL). These data suggest that gastrointestinal transit parameters play a role in the differences in the rapid clearance profile group, also contributing to the biphasic to monophasic switch. However, historical data show, at the recommended dose of 250 mg/day steady-state plasma concentrations adequate for clinical benefit are achieved in patients with non-small cell lung cancer.

  3. Effect of peppermint oil and caraway oil on gastrointestinal motility in healthy volunteers: a pharmacodynamic study using simultaneous determination of gastric and gall-bladder emptying and orocaecal transit time.

    PubMed

    Goerg, K J; Spilker, Th

    2003-02-01

    Although peppermint oil and caraway oil are frequently used in herbal drugs for abdominal discomfort and pain, the pharmacological insights into their effects on the gastrointestinal tract are poor. The pharmacodynamic effects of 90 mg peppermint oil (WS 1340) and 50 mg caraway oil (WS 1520) on the motility of the stomach and gall-bladder, and on the orocaecal transit time, in comparison with placebo, 10 mg cisapride and 10 mg n-butylscopolamine, were studied in 12 healthy volunteers. The study involved simultaneous ultrasonic determination of gastric and gall-bladder emptying, together with assessment of the orocaecal transit time using the lactulose H2 breath test. The combination of these methods allows three gastrointestinal organs to be studied in one subject simultaneously. The antral filling time was comparable with placebo, peppermint oil, caraway oil and cisapride, whereas it was significantly shortened (P = 0.04, two-sided paired t-test) with n-butylscopolamine. The gastric emptying time did not differ significantly between placebo, peppermint oil, caraway oil and cisapride, but was significantly prolonged by n-butylscopolamine (P = 0.04, two-sided paired t-test). Complete inhibition of gall-bladder emptying was caused by both oils and n-butylscopolamine. Cisapride significantly shortened gall-bladder emptying compared with placebo (P = 0.02, two-sided signed rank test). The orocaecal transit time was significantly prolonged by peppermint oil (P = 0.004) and n-butylscopolamine (P = 0.002), but not significantly prolonged by caraway oil (P = 0.06); it was significantly shortened by cisapride (P = 0.04, all two-sided paired t-test). Peppermint oil and caraway oil show a relaxing effect on the gall-bladder and the former slows small intestinal transit. Further studies should investigate the effects of both oils on a maximal contraction stimulus on the gall-bladder, and in patients suffering from motility disorders.

  4. Upper gastrointestinal tract transit times of tablet and drinkable solution formulations of alendronate: a bioequivalence and a quantitative, randomized study using video deglutition.

    PubMed

    Gómez Acotto, Claudia; Antonelli, Carlos; Flynn, Damien; McDaid, Dennis; Roldán, Emilio J A

    2012-11-01

    The bioequivalence and upper digestive tract transit time of a drinkable solution of 70 mg/100 mL alendronate was compared to reference tablets. A randomized, single- dose, two-way crossover study of the rate of urinary recovery of alendronate during 36 h (AE((0-36 h))) by HPLC, in 104 healthy young male volunteers, showed that AE((0-36 h)) and the maximum excretion rate (R (max)) were within the accepted range of bioequivalence 81.8-105.7 and 81.7-106.2, respectively. To characterize the oesophageal passage time of the two alendronate formulations, we performed a randomized, controlled study, in 24 healthy men and women (mean 52 years old), who took the formulations standing or lying down, by an X-ray video deglutition system. When taken in the standing position, both formulations had equal mean transit times from mouth to stomach and tablet disintegration but data dispersion was significantly smaller with the liquid form. When taken in lying position, drinkable alendronate had shorter and less variable median transit times compared to the tablets. These results show that the drinkable alendronate formulation is bioequivalent to the tablets and may be advantageous in patients in whom the transit or disintegration of the tablets is impaired.

  5. Implantable Colonic Electrical Stimulation Improves Gastrointestinal Transit and Defecation in a Canine Constipation Model.

    PubMed

    Chen, Shuo; Li, Yanmei; Yao, Shukun; Zhang, Yanli; Liu, Liang; Guo, Xiaojuan; Chen, Wang; Chen, Yan; Du, Yuhui

    2016-01-01

    Colonic electrical stimulation (CES) may have a therapeutic potential for slow transit constipation (STC). This study aimed to evaluate the effects of implantable CES on gastrointestinal transit and defecation, and explore its mechanisms in a canine STC model. Two pairs of electrodes were implanted in each of the proximal colon and rectosigmoid junction (RSJ). Parameters were individualized according to the symptoms of the stimulated dogs. In the STC model, gastrointestinal transit and defecation were assessed to evaluate the effects of double-site CES, and of double-site CES combined with atropine or N-nitro-L-arginine (L-NNA) in a crossover design. Individualized parameters varied among the animals. The CES significantly shortened gastrointestinal transit time (GITT) and colonic transit time (CTT) compared with sham CES (p = 0.001 and p < 0.001, respectively). Compared with sham CES, the CES also exhibited significantly higher stool frequency and stool consistency score (p = 0.018 and p = 0.001, respectively). Co-treatment with atropine or L-NNA blocked the effects of CES on GITT, CTT, and stool consistency. The stool frequency increased by CES, however, only reduced by co-treatment with L-NNA. This double-site implantable CES can improve the gastrointestinal transit and defecation in a canine STC model, possibly by activating the cholinergic and nitrergic pathways. The CES mode used in this study may be proven feasible in treating STC. © 2015 International Neuromodulation Society.

  6. Transit Timing Variations

    NASA Image and Video Library

    The animation shows the difference between planet transit timing of single and multiple planet system. In tightly packed planetary systems, the gravitational pull of the planets among themselves ca...

  7. Ghrelin improves burn-induced delayed gastrointestinal transit in rats.

    PubMed

    Sallam, H S; Oliveira, H M; Gan, H T; Herndon, D N; Chen, J D Z

    2007-01-01

    Delayed gastrointestinal transit is common in patients with severe burn. Ghrelin is a potent prokinetic peptide. We aimed at testing the effect of ghrelin on burn-induced delayed gastrointestinal transit in rats. Gastric emptying (GE), intestinal transit (IT), and colonic transit (CT) studies were performed in male Sprague-Dawley rats. Rats were randomized into two main groups as follows: sham injury and ghrelin-treated burn injury with doses of 0, 2, 5, and 10 nmol/rat ip 6 h after burn. Sham/burn injury was induced under anesthesia. Rats received a phenol red meal 20 min following ghrelin injection. Based on the most effective ghrelin dose, 1 mg/kg sc atropine was given 30 min before the ghrelin in one group of rats for each study. The rats in each group were killed 30-90 min later; their stomachs, intestines, and colons were harvested immediately, and the amount of phenol red recovered was measured. Percentage of gastric emptying (GE%) and geometric center for IT and CT were calculated. We found 1) severe cutaneous burn injury significantly delayed GE, IT, and CT compared with sham injury (P < 0.05); 2) ghrelin normalized both GE and IT, but not the CT; 3) the most effective dose of ghrelin was 2 nmol/rat; and 4) atropine blocked the prokinetic effects of ghrelin on GE% and IT. In conclusion, ghrelin normalizes burn-induced delayed GE and IT but has no effect on CT in rats. The prokinetic effects of ghrelin are exerted via the cholinergic pathway. Ghrelin may have a therapeutic potential for burn patients with delayed upper gastrointestinal transit.

  8. Evaluation of gastrointestinal transit after infection with different loads of Strongyloides venezuelensis in rats.

    PubMed

    Anjos-Ramos, L; Gama, L A; Mati, V L T; Corá, L A; Fujiwara, R T; Americo, M F

    2016-04-01

    The aim was to correlate the gastrointestinal transit profile in rats, evaluated by a biomagnetic technique, in response to infection with different loads of Strongyloides venezuelensis. Eggs per gram, intestinal number of worms and fecundity, and also gastric emptying time, cecum arrival time, small intestinal transit time and stool weight were determined. Assessments occurred at 0 (control), 3, 6, 9, 12, 15, 18 and 21 days post infection (dpi) with three infective loads (400, 2000, and 10,000 L). Gastric emptying was faster (p=0.0001) and the intestinal transit was significantly slower (p=0.001) during the infection time course. Also, linear mixed-effects models showed significantly changes in small intestinal transit after three parasite load over time. Cecum arrival was not influenced by infection time course or parasite load. As indirect effect, stool weight decreased accompanied a strong oviposition peak at 9 dpi in 400 L and 2000 L. In several motor function instances, neuromuscular dysfunction persists after mucosal inflammation has decreased. Our approach could be very helpful to evaluate gastrointestinal motor abnormalities in vivo after parasite infection. Despite parasitological data progressively decreased after 15 dpi, small intestinal transit worse over time and according to burden.

  9. Variation in gastrointestinal transit of pharmaceutical dosage forms in healthy subjects

    SciTech Connect

    Coupe, A.J.; Davis, S.S.; Wilding, I.R. )

    1991-03-01

    The variability in the gastrointestinal transit of a multiple-unit and single-unit dosage form was investigated following a light breakfast in six, healthy, male volunteers after repeated weekly administration. The dosage forms were labeled with gamma-emitting radionuclides and the transit of the formulations was monitored on 4 separate study days using the technique of dual-isotope gamma scintigraphy. Gastric emptying times and small intestinal transit times were calculated and compared statistically within and between subjects using the standard deviation and coefficient of variance. The variability in gastric emptying of single- and multiple-unit systems was large; the intrasubject variation being less than the intersubject. There was less variation in small intestinal transit times for the single- and multiple-unit formulations than in gastric emptying, intrasubject variation again being less than intersubject variation.

  10. Gastrointestinal transit of undigestible solids measured by metal detector EAS II.

    PubMed

    Ewe, K; Press, A G; Dederer, W

    1989-06-01

    A new method was developed to measure gastrointestinal transit: a metal particle is followed on its way through the gastrointestinal tract by means of a portable metal detector. Deviation of measured localization of the metal particle from the exact site was 0.5-1.0 cm depending on its size and distance from the search probe. A metal sphere of 6 mm diameter can be located accurately in the body at a distance of 2-12 cm from the abdominal surface. Emptying of a metal particle from the stomach, its arrival at the caecal area and its passage through the colon into the rectum can be registered and hence, gastric residence time, small intestinal transit and transit through different parts of the colon were determined. Gastric residence time at the interdigestive phase was (mean +/- SD) 67 +/- 52 min in 20 persons with a range of 9-185 min. When gastric emptying was recorded by pH sensitive radiotelemetering capsule in 10 persons, correlation of both methods was r = 0.99. Small intestinal transit averaged 110 +/- 56 min in six healthy volunteers when breakfast was eaten after the marker had left the stomach. It was delayed to 218 +/- 34 min (P less than 0.01) when fasting was continued. Large intestinal transit of the metal marker was compared to whole body transit of radio-opaque ('Hinton') markers. In nine normal persons, 70% of the Hinton markers were excreted together with the metal particle. It is concluded that this new method is suitable for studying a large variety of physiological, pathophysiological and pharmacological questions concerning gastrointestinal transit.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Clostridium perfringens epsilon toxin inhibits the gastrointestinal transit in mice.

    PubMed

    Losada-Eaton, D M; Fernandez-Miyakawa, M E

    2010-12-01

    Epsilon toxin produced by Clostridium perfringens type B and D is a potent toxin that is responsible for a highly fatal enterotoxemia in sheep and goats. In vitro, epsilon toxin produces contraction of the rat ileum as the result of an indirect action, presumably mediated through the autonomic nervous system. To examine the impact of epsilon toxin in the intestinal transit, gastric emptying (GE) and gastrointestinal transit (GIT) were evaluated after intravenous and oral administration of epsilon toxin in mice. Orally administered epsilon toxin produced a delay on the GIT. Inhibition of the small intestinal transit was observed as early as 1 h after the toxin was administered orally but the effects were not observed after 1 week. Epsilon toxin also produced an inhibition in GE and a delay on the GIT when relatively high toxin concentrations were given intravenously. These results indicate that epsilon toxin administered orally or intravenously to mice transitorily inhibits the GIT. The delay in the GIT induced by epsilon toxin could be relevant in the pathogenesis of C. perfringens type B and D enterotoxemia.

  12. Effects of Buprenorphine, Methylnaltrexone, and Their Combination on Gastrointestinal Transit in Healthy New Zealand White Rabbits.

    PubMed

    Martin-Flores, Manuel; Singh, Bhupinder; Walsh, Courtney A; Brooks, Elizabeth P; Taylor, Lacic; Mitchell, Lisa M

    2017-03-01

    Among the many analgesic agents available, buprenorphine appears to be the analgesic used most often in rabbits. Unfortunately, deleterious side effects of opioids, such as gastrointestinal stasis and anorexia, may discourage the use of these agents. Methylnaltrexone is a peripheral opioid antagonist that ameliorates opioid-induced gastrointestinal stasis in others species yet preserves the analgesic effects of buprenorphine. We evaluated whether methylnaltrexone reversed buprenorphine-induced gastrointestinal stasis in 8 healthy male New Zealand White rabbits. To measure gastrointestinal transit time, each rabbit received 20 barium-filled spheres through an orogastric tube. Rabbits then received 4 treatments in random order: buprenorphine (0.05 mg/kg SC), methylnaltrexone (1 mg/kg SC), both agents combined (B+M), or normal saline (control) every 12 h for 2 d. Fecal production was measured every 6 h, and water and food consumption, and body weight, were measured daily, for 5 d after each treatment. The time to appearance of the first sphere was significantly longer for buprenorphine group than for control and methylnaltrexone groups. Daily fecal output was lowest for buprenorphine and B+M, intermediate for control, and highest for methylnaltrexone. Water and food consumption were lower for groups buprenorphine and B+M than for control and methylnaltrexone. Body weight was not affected. In conclusion, treatment with buprenorphine 0.05 mg/kg BID for 2 d in healthy rabbits decreased food and water consumption, prolonged gastrointestinal transit time and decreased the fecal output. Coadministration of methylnaltrexone at 1 mg/kg did not alleviate these negative side effects.

  13. Effects of Buprenorphine, Methylnaltrexone, and Their Combination on Gastrointestinal Transit in Healthy New Zealand White Rabbits

    PubMed Central

    Martin-Flores, Manuel; Singh, Bhupinder; Walsh, Courtney A; Brooks, Elizabeth P; Taylor, Laci C; Mitchell, Lisa M

    2017-01-01

    Among the many analgesic agents available, buprenorphine appears to be the analgesic used most often in rabbits. Unfortunately, deleterious side effects of opioids, such as gastrointestinal stasis and anorexia, may discourage the use of these agents. Methylnaltrexone is a peripheral opioid antagonist that ameliorates opioid-induced gastrointestinal stasis in others species yet preserves the analgesic effects of buprenorphine. We evaluated whether methylnaltrexone reversed buprenorphine-induced gastrointestinal stasis in 8 healthy male New Zealand White rabbits. To measure gastrointestinal transit time, each rabbit received 20 barium-filled spheres through an orogastric tube. Rabbits then received 4 treatments in random order: buprenorphine (0.05 mg/kg SC), methylnaltrexone (1 mg/kg SC), both agents combined (B+M), or normal saline (control) every 12 h for 2 d. Fecal production was measured every 6 h, and water and food consumption, and body weight, were measured daily, for 5 d after each treatment. The time to appearance of the first sphere was significantly longer for buprenorphine group than for control and methylnaltrexone groups. Daily fecal output was lowest for buprenorphine and B+M, intermediate for control, and highest for methylnaltrexone. Water and food consumption were lower for groups buprenorphine and B+M than for control and methylnaltrexone. Body weight was not affected. In conclusion, treatment with buprenorphine 0.05 mg/kg BID for 2 d in healthy rabbits decreased food and water consumption, prolonged gastrointestinal transit time and decreased the fecal output. Coadministration of methylnaltrexone at 1 mg/kg did not alleviate these negative side effects. PMID:28315644

  14. The influence of telenzepine on gastrointestinal transit: comparison with placebo and domperidone.

    PubMed

    Armbrecht, U; Reul, W; Stockbrügger, R W

    1990-02-01

    In a placebo controlled trial, the effect of the M1-antagonist telenzepine (3 mg in the morning) and of the dopamine antagonist domperidone (10 mg t.d.s.) was studied on bowel habits, on oro-caecal and on oro-anal transit time. The study was carried out on healthy subjects double-blind, multiple cross-over. The test periods were seven days each interrupted by wash-out periods of seven days. Stool weight, frequency and consistency as well as side-effects were recorded daily. The oro-anal transit time was estimated by evaluating the excretion of orally ingested radiopaque markers. The oro-caecal transit time was studied by means of a hydrogen breath test after a standard meal. The oro-caecal transit time was significantly prolonged during medication with telenzepine, both compared with placebo (p less than 0.05) and with domperidone (p less than 0.01). Bowel habits and the oro-anal transit time remained statistically unchanged during treatment with the active drugs. It is concluded that telenzepine has a dissociate effect on intestinal motility, delaying transit through the upper gastrointestinal tract without affecting the oro-anal transit time.

  15. Gastrointestinal transit and disintegration of enteric coated magnetic tablets assessed by ac biosusceptometry.

    PubMed

    Corá, Luciana A; Romeiro, Fernando G; Américo, Madileine F; Oliveira, Ricardo Brandt; Baffa, Oswaldo; Stelzer, Murilo; Miranda, José Ricardo de Arruda

    2006-01-01

    The oral administration is a common route in the drug therapy and the solid pharmaceutical forms are widely used. Although much about the performance of these formulations can be learned from in vitro studies using conventional methods, evaluation in vivo is essential in product development. The knowledge of the gastrointestinal transit and how the physiological variables can interfere with the disintegration and drug absorption is a prerequisite for development of dosage forms. The aim of this work was to employing the ac biosusceptometry (ACB) to monitoring magnetic tablets in the human gastrointestinal tract and to obtain the magnetic images of the disintegration process in the colonic region. The ac biosusceptometry showed accuracy in the quantification of the gastric residence time, the intestinal transit time and the disintegration time (DT) of the magnetic formulations in the human gastrointestinal tract. Moreover, ac biosusceptometry is a non-invasive technique, radiation-free and harmless to the volunteers, as well as an important research tool in the pharmaceutical, pharmacological and physiological investigations.

  16. Excipient effects on gastrointestinal transit and drug absorption in beagle dogs.

    PubMed

    Schulze, Julia D R; Peters, Erin E; Vickers, Ann W; Staton, J Scott; Coffin, Mark D; Parsons, Gary E; Basit, Abdul W

    2005-08-26

    Previous work has shown that polyethylene glycol 400 (PEG 400) has an accelerating effect on gastrointestinal transit and a modulating influence on drug absorption in humans. The aim of this study was to assess the impact of various excipients, PEG 400, propylene glycol, d-alpha-tocopheryl-polyethylene glycol-1000 succinate (TPGS) and Labrasol on gastrointestinal transit and drug absorption in four beagle dogs using scintigraphy. Each dog received, on five separate occasions, water (control) or a dose of excipient equivalent to 1 g PEG 400, 2 g propylene glycol, 1 g TPGS or 2 g Labrasol dissolved in water and administered in the form of two capsules. The model drugs ampicillin (200mg) and antipyrine (100mg) were co-administered in the capsules. The capsule solutions were radiolabelled with technetium-99m to follow their transit using a dual-headed gamma camera, and blood samples were collected to determine drug pharmacokinetics. On a separate occasion, the drugs were dissolved in saline and given intravenously. The capsules rapidly disintegrated in the stomach liberating their liquid contents. The mean small intestinal transit times for the different treatments (control, PEG 400, propylene glycol, TPGS and Labarasol) were 183, 179, 195, 168 and 154 min, respectively. The corresponding mean absolute oral bioavailability figures were 36, 32, 39, 42 and 32% for ampicillin and 76, 74, 85, 73 and 74% for antipyrine, respectively. The transit and bioavailability data for the excipient treatments were not significantly different from the control. In summary, these excipients, at the doses administered, have limited influence on gastrointestinal transit and drug in beagle dogs.

  17. Boundaries, junctions and transitions in the gastrointestinal tract.

    PubMed

    San Roman, Adrianna K; Shivdasani, Ramesh A

    2011-11-15

    Contiguous regions along the mammalian gastrointestinal tract, from the esophagus to the rectum, serve distinct digestive functions. Some organs, such as the esophagus and glandular stomach or the small bowel and colon, are separated by sharp boundaries. The duodenal, jejunal and ileal segments of the small intestine, by contrast, have imprecise borders. Because human esophageal and gastric cancers frequently arise in a background of tissue metaplasia and some intestinal disorders are confined to discrete regions, it is useful to appreciate the molecular and cellular basis of boundary formation and preservation. Here we review the anatomy and determinants of boundaries and transitions in the alimentary canal with respect to tissue morphology, gene expression, and, especially, transcriptional control of epithelial identity. We discuss the evidence for established and candidate molecular mechanisms of boundary formation, including the solitary and combinatorial actions of tissue-restricted transcription factors. Although the understanding remains sparse, genetic studies in mice do provide insights into dominant mechanisms and point the way for future investigation. Copyright © 2011 Elsevier Inc. All rights reserved.

  18. Boundaries, Junctions and Transitions in the Gastrointestinal Tract

    PubMed Central

    San Roman, Adrianna K.; Shivdasani, Ramesh A.

    2011-01-01

    Contiguous regions along the mammalian gastrointestinal tract, from the esophagus to the rectum, serve distinct digestive functions. Some organs, such as the esophagus and glandular stomach or the small bowel and colon, are separated by sharp boundaries. The duodenal, jejunal and ileal segments of the small intestine, by contrast, have imprecise borders. Because human esophageal and gastric cancers frequently arise in a background of tissue metaplasia and some intestinal disorders are confined to discrete regions, it is useful to appreciate the molecular and cellular basis of boundary formation and preservation. Here we review the anatomy and determinants of boundaries and transitions in the alimentary canal with respect to tissue morphology, gene expression, and, especially, transcriptional control of epithelial identity. We discuss the evidence for established and candidate molecular mechanisms of boundary formation, including the solitary and combinatorial actions of tissue-restricted transcription factors. Although the understanding remains sparse, genetic studies in mice do provide insights into dominant mechanisms and point the way for future investigation. PMID:21802415

  19. Transit satellite system timing capabilities

    NASA Technical Reports Server (NTRS)

    Finsod, T. D.

    1978-01-01

    Current time transfer capabilities of the Transit Satellite System are reviewed. Potential improvements in the changes in equipment and operational procedures using operational satellites are discussed.

  20. Complex Interactions Among Diet, Gastrointestinal Transit, and Gut Microbiota in Humanized Mice

    PubMed Central

    Kashyap, Purna C.; Marcobal, Angela; Ursell, Luke K.; Larauche, Muriel; Duboc, Henri; Earle, Kristen A.; Sonnenburg, Erica D.; Ferreyra, Jessica A.; Higginbottom, Steven K.; Million, Mulugeta; Tache, Yvette; Pasricha, Pankaj J.; Knight, Rob; Farrugia, Gianrico; Sonnenburg, Jusin l.

    2013-01-01

    Background & Aims Diet has major effects on the intestinal microbiota, but the exact mechanisms that alter complex microbial communities have been difficult to elucidate. In addition to the direct influence that diet exerts on microbes, changes in microbiota composition and function can alter host functions such as gastrointestinal (GI) transit time, which in turn can further affect the microbiota. Methods We investigated the relationships among diet, GI motility, and the intestinal microbiota using mice that are germ-free (GF) or humanized (ex-GF mice colonized with human fecal microbiota). Results Analysis of gut motility revealed that humanized mice fed a standard polysaccharide-rich diet had faster GI transit and increased colonic contractility compared with GF mice. Humanized mice with faster transit due to administration of polyethylene glycol or a nonfermentable cellulose-based diet had similar changes in gut microbiota composition, indicating that diet can modify GI transit, which then affects the composition of the microbial community. However, altered transit in mice fed a diet of fermentable fructooligosaccharide indicates that diet can change gut microbial function, which can affect GI transit. Conclusions Based on studies in humanized mice, diet can affect GI transit through microbiota-dependent or microbiota-independent pathways, depending on the type of dietary change. The effect of the microbiota on transit largely depends on the amount and type (fermentable vs non-fermentable) of polysaccharides present in the diet. These results have implications for disorders that affect GI transit and gut microbial communities, including irritable bowel syndrome and inflammatory bowel disease. PMID:23380084

  1. Effects on gastrointestinal transit and antroduodenojejunal manometry after gut-directed hypnotherapy in irritable bowel syndrome (IBS).

    PubMed

    Lindfors, Perjohan; Törnblom, Hans; Sadik, Riadh; Björnsson, Einar S; Abrahamsson, Hasse; Simrén, Magnus

    2012-12-01

    Gut-directed hypnotherapy is an effective treatment in irritable bowel syndrome (IBS) but little is known about the mechanisms of action. In this study we aimed to investigate the effects on gastrointestinal motility when treating IBS with gut-directed hypnotherapy. We randomized 90 patients with IBS, refractory to standard management to receive gut-directed hypnotherapy 1 h/week for 12 weeks or supportive treatment for the same time period. Eighty-one subjects (40 hypnotherapy, 41 controls) could be evaluated by one or more of the following investigations, both before and after the intervention: gastric emptying time, small bowel transit time, colonic transit time, and antroduodenojejunal manometry. No significant differences in gastric emptying time, small bowel transit time, or colonic transit time was found when comparing the baseline and post-intervention measurements in the hypnotherapy group or in the control group. The same was true concerning the results of the antroduodenojejunal manometry. However, there was a numerical trend toward a higher number of migrating motor complexes at manometry and an accelerated gastric emptying time after hypnotherapy that did not reach statistical significance. In this study, we were not able to find evidence for long-standing effects on gastrointestinal motility as a mediator of the effects on IBS when treating the condition with gut-directed hypnotherapy. Further research to understand the mechanism of action is needed.

  2. Transit Timing Study of Kepler Planets

    NASA Astrophysics Data System (ADS)

    Xie, Jiwei

    2015-08-01

    Kepler space telescope has found over 4000 transiting planet candidates. Transit timing is a powerful tool to study these transit planet candidates. In this talk, I will talk about two transit timing techniques, i.e., transit timing variation (TTV) and transit duration (TD), which enable confirming their planetary nature and obtaining insight into their orbital properties.

  3. Cerebral, spinal and peripheral inhibition of gastrointestinal transit by PI017: differential antagonism by naloxonazine

    SciTech Connect

    Williams, C.L.; Heyman, J.S.; Porreca, F.; Burks, T.F.

    1986-03-05

    The authors were interested in characterizing the relative importance of central (cerebral, spinal) and peripheral opioid receptors in inhibition of gastrointestinal transit. The mu-receptor selective agonist, (NMePhe/sup 3/,D-Pro/sup 4/)morphiceptin (PL017), was evaluated for its effectiveness in slowing gastrointestinal transit after subcutaneous, intracerebroventricular (i.c.v.) or intrathecal (i.th.) administration when given alone or after pretreatment with naloxonazine, an irreversible mu/sub 1/ selective opioid receptor antagonist. Male, ICR mice (20-25 g) were pretreated with saline, naloxone or naloxonazine (35 mg/kg, s.c.) 25 hr prior to testing. Gastrointestinal transit was evaluated in previously fasted (18 hr) mice by oral administration of a liquid radiolabelled marker (Na/sub 2//sup 51/CrO/sub 4/). I.th. PL017 (100-1000 ng) was effective in slowing transit, but was essentially insensitive to naloxone or naloxonazine pretreatment. PL017 produced a dose-related inhibition of transit when given by either the i.c.v. (100-1000 ng) or s.c.(1-10 mg/kg) route; this effect was not sensitive to naloxone pretreatment but was antagonized by naloxonazine. These results indicate that the opioid receptors mediating gastrointestinal transit in the brain and periphery may be mu/sub 1/. In contrast, the insensitivity to naloxonazine suggests that the gastrointestinal effects of PL017 in the spinal cord may be the result of activation of mu/sub 2/ or possibly delta opioid receptors.

  4. Comparison of selective M3 and nonselective muscarinic receptor antagonists on gastrointestinal transit and bowel habits in humans

    PubMed Central

    Ravi, Karthik; Zinsmeister, Alan R.

    2010-01-01

    Although in vitro studies show that muscarinic M3 receptors primarily mediate the effects of acetylcholine on gastrointestinal contractility, the muscarinic receptor subtypes regulating gastrointestinal motor activity and transit in humans in vivo are unclear. We hypothesized that muscarinic M3-specific but not nonspecific receptor antagonists would delay gastrointestinal and colonic transit in humans. In this parallel-group study, gastric emptying, small intestinal transit, and colonic transit were assessed by scintigraphy on days 4-6 in 72 healthy subjects (49 women) who received placebo (n = 16), the M3 antagonist darifenacin ER [7.5 mg (n = 20) or 15 mg daily (n = 17)], or the nonspecific antagonist tolterodine [4 mg daily (n = 19)] for 6 days. Bowel habits were recorded by daily diaries. Both doses of darifenacin substantially delayed [P < 0.01 vs. placebo (for both doses), P < 0.01 vs. tolterodine (for 15 mg)] small intestinal transit, i.e., colonic filling at 6 h (placebo [59.6 ± 6.4%, mean ± SE], 7.5 mg ER [34.4 ± 6.1%], 15 mg ER [20.4 ± 6.3%)]. Darifenacin (15 mg) also delayed (P < 0.01 vs. placebo and tolterodine) half-time for ascending colonic emptying [placebo (12.0 ± 1.5 h), 7.5 mg (18.6 ± 1.9 h), 15 mg (22.9 ± 2.6 h)] and colonic transit (geometric center) at 24 [placebo (2.8 ± 0.2), 7.5 mg (2.4 ± 0.2), 15 mg (1.9 ± 0.2)] but not 48 h. Darifenacin did not affect gastric emptying and tolterodine did not affect bowel habits or gastrointestinal transit. With muscarinic antagonists used at clinically approved doses, these findings demonstrate that muscarinic M3 receptors regulate small intestinal and colonic transit in humans; colonic effects are more pronounced in the right than left colon. At doses that affect small and large intestinal transit, M3 antagonists do not affect gastric emptying in humans. The efficacy of darifenacin in diarrhea-predominant irritable bowel syndrome should be evaluated. PMID:20395537

  5. Comparison of selective M3 and nonselective muscarinic receptor antagonists on gastrointestinal transit and bowel habits in humans.

    PubMed

    Bharucha, Adil E; Ravi, Karthik; Zinsmeister, Alan R

    2010-07-01

    Although in vitro studies show that muscarinic M(3) receptors primarily mediate the effects of acetylcholine on gastrointestinal contractility, the muscarinic receptor subtypes regulating gastrointestinal motor activity and transit in humans in vivo are unclear. We hypothesized that muscarinic M(3)-specific but not nonspecific receptor antagonists would delay gastrointestinal and colonic transit in humans. In this parallel-group study, gastric emptying, small intestinal transit, and colonic transit were assessed by scintigraphy on days 4-6 in 72 healthy subjects (49 women) who received placebo (n = 16), the M(3) antagonist darifenacin ER [7.5 mg (n = 20) or 15 mg daily (n = 17)], or the nonspecific antagonist tolterodine [4 mg daily (n = 19)] for 6 days. Bowel habits were recorded by daily diaries. Both doses of darifenacin substantially delayed [P < 0.01 vs. placebo (for both doses), P < 0.01 vs. tolterodine (for 15 mg)] small intestinal transit, i.e., colonic filling at 6 h (placebo [59.6 +/- 6.4%, mean +/- SE], 7.5 mg ER [34.4 +/- 6.1%], 15 mg ER [20.4 +/- 6.3%)]. Darifenacin (15 mg) also delayed (P < 0.01 vs. placebo and tolterodine) half-time for ascending colonic emptying [placebo (12.0 +/- 1.5 h), 7.5 mg (18.6 +/- 1.9 h), 15 mg (22.9 +/- 2.6 h)] and colonic transit (geometric center) at 24 [placebo (2.8 +/- 0.2), 7.5 mg (2.4 +/- 0.2), 15 mg (1.9 +/- 0.2)] but not 48 h. Darifenacin did not affect gastric emptying and tolterodine did not affect bowel habits or gastrointestinal transit. With muscarinic antagonists used at clinically approved doses, these findings demonstrate that muscarinic M(3) receptors regulate small intestinal and colonic transit in humans; colonic effects are more pronounced in the right than left colon. At doses that affect small and large intestinal transit, M(3) antagonists do not affect gastric emptying in humans. The efficacy of darifenacin in diarrhea-predominant irritable bowel syndrome should be evaluated.

  6. Inactivation of Bacillus cereus vegetative cells by gastric acid and bile during in vitro gastrointestinal transit

    PubMed Central

    2012-01-01

    Background The foodborne pathogen Bacillus cereus can cause diarrhoeal food poisoning by production of enterotoxins in the small intestine. The prerequisite for diarrhoeal disease is thus survival during gastrointestinal passage. Methods Vegetative cells of 3 different B. cereus strains were cultivated in a real composite food matrix, lasagne verde, and their survival during subsequent simulation of gastrointestinal passage was assessed using in vitro experiments simulating transit through the human upper gastrointestinal tract (from mouth to small intestine). Results No survival of vegetative cells was observed, despite the high inoculum levels of 7.0 to 8.0 log CFU/g and the presence of various potentially protective food components. Significant fractions (approx. 10% of the consumed inoculum) of B. cereus vegetative cells survived gastric passage, but they were subsequently inactivated by bile exposure in weakly acidic intestinal medium (pH 5.0). In contrast, the low numbers of spores present (up to 4.0 log spores/g) showed excellent survival and remained viable spores throughout the gastrointestinal passage simulation. Conclusion Vegetative cells are inactivated by gastric acid and bile during gastrointestinal passage, while spores are resistant and survive. Therefore, the physiological form (vegetative cells or spores) of the B. cereus consumed determines the subsequent gastrointestinal survival and thus the infective dose, which is expected to be much lower for spores than vegetative cells. No significant differences in gastrointestinal survival ability was found among the different strains. However, considerable strain variability was observed in sporulation tendency during growth in laboratory medium and food, which has important implications for the gastrointestinal survival potential of the different B. cereus strains. PMID:23034184

  7. Escin: inhibiting inflammation and promoting gastrointestinal transit to attenuate formation of postoperative adhesions.

    PubMed

    Fu, Fenghua; Hou, Yuezhi; Jiang, Wanglin; Wang, Ronghua; Liu, Ke

    2005-12-01

    Postoperative peritoneal adhesions are common, serious complications of general abdominal and gynecologic surgery that can lead to chronic abdominal pain, intestinal obstruction, and infertility. As yet, there are no ideal drugs that may be prescribed for patients to prevent adhesion formation effectively. In this study the effects of escin, a natural drug, on the various steps of adhesion formation were investigated. The effects of escin on increased vascular permeability induced by acetic acid in a mouse model of acute inflammation, granuloma formation in a subchronic inflammatory rat model, gastrointestinal transit in rats with intestinal paralysis, intestinal motility in postoperative patients, and postoperative adhesion formation in a rat model were observed. It was shown that escin could inhibit acute inflammation and granuloma formation, cause acceleration of gastrointestinal transit, help recover intestinal motility, and attenuate the formation of postoperative adhesions. The findings suggest that escin attenuates the formation of postoperative adhesions by inhibiting inflammation and promoting gastrointestinal transit. Thus it may be concluded that both inhibition of inflammation and increased gastrointestinal motility during the early postoperative period have a positive effect on decreasing the formation of adhesions.

  8. Transit times in turbulent flows.

    PubMed

    Pécseli, H L; Trulsen, J

    2010-04-01

    Statistics of the motion of passively convected point particles in turbulent flows are studied. The database used is obtained by direct numerical solution of the Navier-Stokes equation. We estimate the probability distribution of the transit times of such particles through reference volumes with given forms and sizes. A selected position within the reference volume is moving with the local flow velocity, thus determining the motion of the entire surface. The transit time is defined as the interval between entrance and exit times of surrounding particles convected through the volume by the turbulent motions. Spherical as well as hemispherical surfaces are studied. Scale sizes in the inertial as well as in the viscous subranges of the turbulence are considered. Simple, and seemingly universal, scaling laws are obtained for the probability density of the transit times in terms of the basic properties of the turbulent flow and the geometry. In the present formulation, the results of the analysis are relevant for chemical reactions, but also for understanding details of the feeding rate of micro-organisms in turbulent waters, for instance.

  9. Pilot study trialling a new ambulatory method for the clinical assessment of regional gastrointestinal transit using multiple electromagnetic capsules.

    PubMed

    Haase, A M; Gregersen, T; Schlageter, V; Scott, M S; Demierre, M; Kucera, P; Dahlerup, J F; Krogh, K

    2014-12-01

    Gastrointestinal (GI) motor disorders often involve several regions of the GI tract. Therefore, easy and safe assessment of whole gut and regional motility is valuable for more precise diagnosis. 3D-Transit is a novel method for ambulatory evaluation of total and regional gastrointestinal transit times (GITT) based on the anatomical localization of ingestible electromagnetic capsules. The main purpose of this study was to test the performance of the 3D-Transit system. Twenty healthy volunteers each ingested three electromagnetic capsules over a period of two consecutive days. Standard radio-opaque markers (ROM) were also ingested to assess the agreement between total GITT obtained with both methods. Investigations were well-tolerated and three capsules could be tracked simultaneously with minimal data loss (Capsule 1: median: 0.2% of time (range 0-25.3%). Region specific contraction patterns were identified and used for computation of total and regional GITT in all subjects. Inter-observer agreement was 100% for total GITT (median variation 0%) but less for regional GITT. Day-to-day and diurnal variations were significant for total and regional GITT. Total GITT assessed by 3D-Transit capsules were moderately well-correlated to those assessed with standard ROM (Spearman's rho = 0.7). 3D-transit is a well-tolerated and minimal invasive ambulatory method for assessment of GI motility. By providing both total and regional transit times, the 3D-Transit system holds great promise for future clinical studies of GI function in health and disease. © 2014 John Wiley & Sons Ltd.

  10. Diabetes attenuates the inhibitory effects of endomorphin-2, but not endomorphin-1 on gastrointestinal transit in mice.

    PubMed

    Wang, Chang-lin; Diao, Yu-xiang; Xiang, Qiong; Ren, Yu-kun; Gu, Ning

    2014-09-05

    Diabetes affects the entire gastrointestinal tract from the esophagus to the anus. In the present study, the charcoal meal test was undertaken to evaluate and compare the effects of intracerebroventricular (i.c.v.) administration of endomorphins (EMs) on gastrointestinal transit in non-diabetic and diabetic mice. Significantly delayed gastrointestinal transit was found in both 4 and 8 weeks alloxan-induced diabetes compared to non-diabetes. Moreover, i.c.v. EM-1 and EM-2 dose-dependently delayed gastrointestinal transit in non-diabetes and diabetes. The EM-1-induced inhibitory effects of gastrointestinal transit in 4 weeks diabetes were qualitatively similar to those of non-diabetes. However, at higher doses, the EM-1-induced effects in 8 weeks diabetes were largely enhanced. Different to EM-1, the EM-2-induced inhibition of gastrointestinal transit in diabetic mice was significantly attenuated compared to non-diabetic mice. Moreover, these effects were further decreased in 8 weeks diabetes. The delayed gastrointestinal transit effects caused by EM-1 may be primarily mediated by μ2-opioid receptor in both non-diabetes and 4 weeks diabetes. Interestingly, in 8 weeks diabetes, these effects were mediated by μ2- and δ-receptors. However, the inhibitory effects of EM-2 were mediated by μ1-opioid receptor, which exerted a reduced function in diabetes. Also, poor blood glucose control might result in the attenuated effects of EM-2. Our present results demonstrated that diabetes attenuates the inhibitory effects of EM-2, but not EM-1 on gastrointestinal transit in mice. The different effects of EM-1 and EM-2 on gastrointestinal transit in diabetes may be due to changes of opioid receptor subtypes and their functional responses.

  11. Synbiotic Microcapsules That Enhance Microbial Viability during Nonrefrigerated Storage and Gastrointestinal Transit

    PubMed Central

    Crittenden, Ross; Weerakkody, Rangika; Sanguansri, Luz; Augustin, MaryAnn

    2006-01-01

    A Bifidobacterium infantis strain was microencapsulated within a film-forming protein-carbohydrate-oil emulsion. This novel encapsulant incorporated prebiotics and substantially protected the bacterium during nonrefrigerated storage and gastrointestinal transit. The dried microcapsules were small (15 to 20 μm), had low water activity (0.2 to 0.3), and rapidly released the bacteria in simulated intestinal fluid. PMID:16517688

  12. Disturbances of gastrointestinal transit and autonomic functions in postural orthostatic tachycardia syndrome.

    PubMed

    Loavenbruck, A; Iturrino, J; Singer, W; Sletten, D M; Low, P A; Zinsmeister, A R; Bharucha, A E

    2015-01-01

    Gastrointestinal symptoms are common in the postural orthostatic tachycardia syndrome (POTS). However, few studies have evaluated gastrointestinal transit in POTS. Our primary objectives were to evaluate gastrointestinal emptying and the relationship with autonomic dysfunctions in POTS. We reviewed the complete medical records of all patients aged 18 years and older with POTS diagnosed by a standardized autonomic reflex screen who also had a scintigraphic assessment of gastrointestinal transit at Mayo Clinic Rochester between 1998 and 2012. Associations between specific gastric emptying and autonomic (i.e., cardiovagal, adrenergic, and sudomotor) disturbances were evaluated. Among 163 patients (140 women, mean [± SEM] age 30 [± 1] years), 55 (34%) had normal, 30 (18%) had delayed, and 78 (48%) had rapid gastric emptying. Fifty-eight patients (36%) had clinical features of physical deconditioning, which was associated (p = 0.02) with rapid gastric emptying. Associations with delayed gastric emptying included vomiting, which was more common (p < 0.003), and anxiety or depression, which was less common (p = 0.02). The tilt-associated increase in heart rate and reduction in systolic BP at 1 min was associated (p < 0.05), being greater in patients with delayed gastric emptying. Two-thirds of patients with POTS and GI symptoms had abnormal, most frequently rapid gastric emptying. Except for more severe adrenergic impairment in patients with delayed gastric emptying, the pattern of autonomic dysfunction did not discriminate among gastric emptying groups. Further studies are necessary to ascertain whether extravascular volume depletion and/or deconditioning contribute to POTS in patients with gastrointestinal symptoms. © 2014 John Wiley & Sons Ltd.

  13. Effect of ageing on the gastro-intestinal transit of a lactulose-supplemented mixed solid-liquid meal in humans.

    PubMed

    Wegener, M; Börsch, G; Schaffstein, J; Lüth, I; Rickels, R; Ricken, D

    1988-01-01

    Gastro-intestinal transit of a mixed solid-liquid meal containing wheat bread, scrambled eggs, coffee labelled with 99mTc, orange juice with lactulose and indigocarmine was evaluated in 21 young control (mean age 33.5 years) and 25 elderly subjects (mean age 81.7 years) without gastrointestinal complaints or severe medical illness. The rate of gastric emptying was determined by an anterior gamma camera technique, mouth-to-caecum transit by the hydrogen breath test and whole-gut transit by the first stool passage of indigocarmine. Gastric emptying was significantly prolonged in older subjects: t1/2 = 136 +/- (SEM) 13 versus 81 +/- 4 min; p less than 0.001. Concerning mouth-to-caecum or whole-gut transit time, significant differences between the two study groups were not detected.

  14. On transit time instability in liquid jets

    NASA Technical Reports Server (NTRS)

    Grabitz, G.; Meier, G.

    1982-01-01

    A basic transit time instability in flows with disturbances of speed is found. It was shown that the mass distribution is established by and large by the described transit time effects. These transit time effects may also be involved for gas jets.

  15. Analyses of some exoplanets' transits and transit timing variations

    NASA Astrophysics Data System (ADS)

    Püsküllü, ćaǧlar; Soydugan, Faruk

    2017-02-01

    We present solutions of the transit light curves and transit timing variations (TTVs) analyses of the exoplanets HAT-P-5b, HAT-P-9b and HAT-P-25b. Transit light curves were collected at Çanakkale Onsekiz Mart University Observatory and TUBITAK National Observatory. The models were produced by WINFITTER program and stellar, planetary and orbital properties were obtained and discussed. We gave new transit times and generated TTVs with them by appending additional data based on Exoplanet Transit Database (ETD). Significant signals at the TTVs were also investigated.

  16. Sex- and smoke-related differences in gastrointestinal transit of cyclosporin A microemulsion capsules.

    PubMed

    Fagiolino, Pietro; Vázquez, Marta; Ibarra, Manuel; Magallanes, Laura; Guevara, Natalia; Fotaki, Nikoletta

    2014-10-15

    The aim of this work was to study the effect of the sex and the smoking status on the pharmacokinetics and the bioequivalence assessment of a branded and a generic cyclosporine A microemulsion formulation in soft-gelatin capsule. Sixteen healthy volunteers (eight women and eight men) participated in a CyA bioequivalence study, with nine of the volunteers being smokers. Sandimmun Neoral® (brand formulation; Reference) and Sigmasporin Microral® (generic formulation; Test) were administered under fasting conditions. Pharmacokinetic parameters were calculated through non compartmental analysis. Bioequivalence was declared based on the 90% confidence intervals (90% CI) for the T/R ratio of the geometric means for each parameter. In vitro determination of the capsules opening time was performed in simulated gastric fluid without enzyme with USP Apparatus 2. The extent of absorption was similar between both products for all subjects or each sex-group. The absorption rate was similar for both products when considering all subjects, whereas a significant difference in the TMAX between the two products was observed for the male subjects only, which relates to its slower capsule opening time observed in vitro (12.4 versus 6.0 min). No differences were observed in women that could relate to their slower gastric emptying. Differences in drug exposure were observed between smokers and non-smokers. Sex- and smoke-related differences in the gastrointestinal transit should be considered when the on-set time would be determinant for the treatment success of a drug. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Tracking gastrointestinal transit of solids in aged rats as pharmacological models of chronic dysmotility.

    PubMed

    Dalziel, J E; Young, W; Bercik, P; Spencer, N J; Ryan, L J; Dunstan, K E; Lloyd-West, C M; Gopal, P K; Haggarty, N W; Roy, N C

    2016-08-01

    Dysmotility in the gastrointestinal (GI) tract often leads to impaired transit of luminal contents leading to symptoms of diarrhea or constipation. The aim of this research was to develop a technique using high resolution X-ray imaging to study pharmacologically induced aged rat models of chronic GI dysmotility that mimic accelerated transit (diarrhea) or constipation. The 5-hydroxytryptamine type 4 (5-HT4 ) receptor agonist prucalopride was used to accelerate transit, and the opioid agonist loperamide was used to delay transit. Male rats (18 months) were given 0, 1, 2, or 4 mg/kg/day prucalopride or loperamide (in dimethyl sulfoxide, DMSO) for 7 days by continuous 7-day dosing. To determine the GI region-specific effect, transit of six metallic beads was tracked over 12 h using high resolution X-ray imaging. An established rating scale was used to classify GI bead location in vivo and the distance beads had propagated from the caecum was confirmed postmortem. Loperamide (1 mg/kg) slowed stomach emptying and GI transit at 9 and 12 h. Prucalopride (4 mg/kg) did not significantly alter GI transit scores, but at a dose of 4 mg/kg beads had moved significantly more distal than the caecum in 12 h compared to controls. We report a novel high-resolution, non-invasive, X-ray imaging technique that provides new insights into GI transit rates in live rats. The results demonstrate that loperamide slowed overall transit in aged rats, while prucalopride increased stomach emptying and accelerates colonic transit. © 2016 The Authors. Neurogastroenterology & Motility Published by John Wiley & Sons Ltd.

  18. Mean transit time: proof and esophageal example

    SciTech Connect

    Klein, H.A.

    1988-03-01

    The transit of radioactive tracers in human systems provides information of physiologic and diagnostic importance. A simple, non-technical proof is offered for the formula for computation of mean transit time as area/height of a time-activity curve. It is specifically applicable to esophageal transit, and may also serve to illuminate other uses in nuclear medicine. The alternative centroid formula for mean transit time differs in meaning but is compatible with the area/height formula. Considerations regarding mean transit time suggest ways to determine the attenuation of radioactivity that affects a compartment under study.

  19. Novel MRI tests of orocecal transit time and whole gut transit time: studies in normal subjects

    PubMed Central

    Chaddock, G; Lam, C; Hoad, C L; Costigan, C; Cox, E F; Placidi, E; Thexton, I; Wright, J; Blackshaw, P E; Perkins, A C; Marciani, L; Gowland, P A; Spiller, R C

    2014-01-01

    Background Colonic transit tests are used to manage patients with Functional Gastrointestinal Disorders. Some tests used expose patients to ionizing radiation. The aim of this study was to compare novel magnetic resonance imaging (MRI) tests for measuring orocecal transit time (OCTT) and whole gut transit time (WGT), which also provide data on colonic volumes. Methods 21 healthy volunteers participated. Study 1: OCTT was determined from the arrival of the head of a meal into the cecum using MRI and the Lactose Ureide breath test (LUBT), performed concurrently. Study 2: WGT was assessed using novel MRI marker capsules and radio-opaque markers (ROMs), taken on the same morning. Studies were repeated 1 week later. Key Results OCTT measured using MRI and LUBT was 225 min (IQR 180–270) and 225 min (IQR 165–278), respectively, correlation rs = 0.28 (ns). WGT measured using MRI marker capsules and ROMs was 28 h (IQR 4–50) and 31 h ± 3 (SEM), respectively, correlation rs = 0.85 (p < 0.0001). Repeatability assessed using the intraclass correlation coefficient (ICC) was 0.45 (p = 0.017) and 0.35 (p = 0.058) for MRI and LUBT OCTT tests. Better repeatability was observed for the WGT tests, ICC being 0.61 for the MRI marker capsules (p = 0.001) and 0.69 for the ROM method (p < 0.001) respectively. Conclusions & Inferences The MRI WGT method is simple, convenient, does not use X-ray and compares well with the widely used ROM method. Both OCTT measurements showed modest reproducibility and the MRI method showed modest inter-observer agreement. PMID:24165044

  20. Bead study: a novel method to measure gastrointestinal transit in mice.

    PubMed

    Reed, D E; Pigrau, M; Lu, J; Moayyedi, P; Collins, S M; Bercik, P

    2014-11-01

    Intestinal transit assessment in mice using existing methods requires long recording periods or euthanization of animals to localize a tracer. We have developed a novel in vivo method to assess gastrointestinal (GI) transit in mice based on a clinically used 'shapes study'. Mice (n = 70) were gavaged with 5 steel beads and barium 3 h before, with another dose of barium gavaged 10 min before imaging. Mice were fluoroscoped for 20-60 s, and then most of them were euthanized and the GI tract removed to confirm the localization of the beads fluoroscopically. The in vivo and postmortem recordings were analyzed and each bead was scored depending on its location; a total score was calculated by adding individual bead scores. Total scores obtained from the two methods were compared. A group of mice (n = 10) were examined on three occasions, before and after treatment with loperamide or prucalopride. The stomach and cecum were consistently outlined by barium, serving as reference landmarks. There was an excellent overall correlation between in vivo and postmortem transit scores (r = 0.93). Analysis of scores for individual gut segments revealed high agreement for stomach, cecum, and expelled beads, and moderate agreement for the small bowel and colon. Gastrointestinal transit scores were decreased by loperamide and increased by prucalopride compared with baseline. Metallic beads are reliably localized by videofluoroscopy in vivo within the GI tract. This novel imaging method enables repetitive measurements of GI transit in vivo and detects changes induced by motility-modifying agents. © 2014 John Wiley & Sons Ltd.

  1. Not ready for prime time: transitional events in the extremely preterm infant.

    PubMed

    Armentrout, Debra

    2014-01-01

    Successful transition from intrauterine to extrauterine life involves significant physiologic changes. The majority of these changes occur relatively quickly during those first moments following delivery; however, transition for the extremely preterm infant occurs over a longer period of time. Careful assessment and perceptive interventions on the part of neonatal care providers is essential as the extremely preterm infant adjusts to life outside the womb. This article will focus on respiratory, cardiovascular, gastrointestinal, and neurologic transitional events experienced by the extremely premature infant.

  2. How to assess regional and whole gut transit time with wireless motility capsule.

    PubMed

    Lee, Yeong Yeh; Erdogan, Askin; Rao, Satish S C

    2014-04-30

    Assessment of transit through the gastrointestinal tract provides useful information regarding gut physiology and patho-physiology. Although several methods are available, each has distinct advantages and limitations. Recently, an ingestible wire-less motility capsule (WMC), similar to capsule video endoscopy, has become available that offers a less-invasive, standardized, radiation-free and office-based test. The capsule has 3 sensors for measurement of pH, pressure and temperature, and collec-tively the information provided by these sensors is used to measure gastric emptying time, small bowel transit time, colonic transit time and whole gut transit time. Current approved indications for the test include the evaluation of gastric emptying in gastroparesis, colonic transit in constipation and evaluation of generalised dysmotility. Rare capsule retention and malfunc-tion are known limitations and some patients may experience difficulty with swallowing the capsule. The use of WMC has been validated for the assessment of gastrointestinal transit. The normal range for transit time includes the following: gastric empty-ing (2-5 hours), small bowel transit (2-6 hours), colonic transit (10-59 hours) and whole gut transit (10-73 hours). Besides avoiding the use of multiple endoscopic, radiologic and functional gastrointestinal tests, WMC can provide new diagnoses, leads to a change in management decision and help to direct further focused work-ups in patients with suspected disordered motility. In conclusion, WMC represents a significant advance in the assessment of segmental and whole gut transit and mo-tility, and could prove to be an indispensable diagnostic tool for gastrointestinal physicians worldwide.

  3. Ghrelin improves delayed gastrointestinal transit in alloxan-induced diabetic mice.

    PubMed

    Qiu, Wen-Cai; Wang, Zhi-Gang; Lv, Ran; Wang, Wei-Gang; Han, Xiao-Dong; Yan, Jun; Wang, Yu; Zheng, Qi; Ai, Kai-Xing

    2008-04-28

    To investigate the effects of ghrelin on delayed gastrointestinal transit in alloxan-induced diabetic mice. A diabetic mouse model was established by intraperitoneal injection with alloxan. Mice were randomized into two main groups: normal mice group and diabetic mice group treated with ghrelin at doses of 0, 20, 50, 100 and 200 mug/kg ip. Gastric emptying (GE), intestinal transit (IT), and colonic transit (CT) were studied in mice after they had a phenol red meal following injection of ghrelin. Based on the most effective ghrelin dosage, atropine was given at 1 mg/kg 15 min before the ghrelin injection for each measurement. The mice in each group were sacrificed 20 min later and their stomachs, intestines, and colons were harvested immediately. The amount of phenol red was measured. Percentages of GE, IT, and CT were calculated. Percentages of GE, IT, and CT were significantly decreased in diabetic mice as compared to control mice (22.9 +/- 1.4 vs 28.1 +/- 1.3, 33.5 +/- 1.2 vs 43.2 +/- 1.9, 29.5 +/- 1.9 vs 36.3 +/- 1.6, P < 0.05). In the diabetic mice, ghrelin improved both GE and IT, but not CT. The most effective dose of ghrelin was 100 mug/kg and atropine blocked the prokinetic effects of ghrelin on GE and IT. Ghrelin accelerates delayed GE and IT but has no effect on CT in diabetic mice. Ghrelin may exert its prokinetic effects via the cholinergic pathway in the enteric nervous system, and therefore has therapeutic potential for diabetic patients with delayed upper gastrointestinal transit.

  4. A randomised, placebo-controlled trial comparing the effects of tapentadol and oxycodone on gastrointestinal and colonic transit in healthy humans.

    PubMed

    Jeong, I D; Camilleri, M; Shin, A; Iturrino, J; Boldingh, A; Busciglio, I; Burton, D; Ryks, M; Rhoten, D; Zinsmeister, A R

    2012-05-01

    Tapentadol is a mu-opioid receptor agonist and norepinephrine reuptake inhibitor. In clinical trials, tapentadol provided somatic pain relief comparable to mu-opioids such as oxycodone, with significantly less gastrointestinal adverse effects. The acute effects of tapentadol on gastrointestinal and colonic transit are unclear. To compare acute effects of oral tapentadol and oxycodone on gastric, small bowel and colonic transit of solids in 38 healthy human subjects. In a randomised, parallel-group, double-blind, placebo-controlled study of the effects of identical-appearing tapentadol immediate release (IR), 75 mg t.d.s., or oxycodone IR, 5 mg t.d.s., for 48 h, we measured gastric (GE), small bowel (SBT measured as colonic filling at 6 h) and colonic transit by validated scintigraphy. Drug was commenced on the evening before the start of the transit test. The primary endpoints were overall colonic transit (geometric centre, GC) at 24 h and GE half-time (t1/2 ). ancova of transit data included gender or BMI as covariates. Adverse effects were summarised. At the doses tested, oxycodone and tapentadol significantly delayed GE t1/2 and SBT, but not overall colonic transit, compared to placebo. Transit profiles in all regions were not significantly different between oxycodone and tapentadol at the doses tested. Both oxycodone and tapentadol were associated with nausea and central effects attributable to central opiate effects. Tapentadol significantly delayed gastric emptying t1/2 and small bowel transit, similar to oxycodone. These data suggest that acute administration of tapentadol may not have significant advantages over standard mu-opioids, in terms of the potential to avoid upper gastrointestinal motor dysfunction. © 2012 Blackwell Publishing Ltd.

  5. Acute and chronic effects of desvenlafaxine on gastrointestinal transit and motility in dogs.

    PubMed

    Song, J; Yin, J; Chen, J D Z

    2013-10-01

    Antidepressants are commonly used for treating functional gastrointestinal (GI) diseases. However, little is known whether antidepressants improve or impair GI motility. This study aimed at exploring possible effects of a serotonin-norepinephrine reuptake inhibitor, desvenlafaxine succinate (DVS), on GI motility in dogs. Eight dogs chronically implanted with a duodenal cannula and a colon cannula were used in the study. Experiments were performed to assess the effects of a single dose of DVS (50 or 100 mg) and DVS given 50 mg once a day for 2 weeks on gastric emptying of solid, small intestinal transit, and colon transit and contractions. (1) DVS significantly delayed gastric emptying of solid at a single dose of 50 or 100 mg. The inhibitory effect on gastric emptying was completely blocked by guanethidine (an adrenergic blocking agent). (2) DVS at a single dose of 50 or 100 mg accelerated colon transit, but showed no effects on small bowel transit. (3) DVS at a single dose of 50 mg enhanced colon contractions and guanethidine blocked the effect. (4) Surprisingly, DVS given at 50 mg once daily for 2 weeks did not alter gastric emptying, small bowel transit or colon transit. Acute DVS delays gastric emptying of solid and enhances the contractions of the colon, which may be mediated via the sympathetic mechanism. Acute DVS promotes the transit of the colon but not the small intestine. However, chronic administration of DVS does not seem to alter GI motility. © 2013 John Wiley & Sons Ltd.

  6. NO TRANSIT TIMING VARIATIONS IN WASP-4

    SciTech Connect

    Petrucci, R.; Schwartz, M.; Buccino, A. P.; Mauas, P. J. D.; Jofré, E.; Cúneo, V.; Gómez, M.; Martínez, C.

    2013-12-20

    We present six new transits of the system WASP-4. Together with 28 light curves published in the literature, we perform a homogeneous study of its parameters and search for variations in the transits' central times. The final values agree with those previously reported, except for a slightly lower inclination. We find no significant long-term variations in i or R{sub P} /R {sub *}. The O-C mid-transit times do not show signs of transit timing variations greater than 54 s.

  7. Gastrointestinal transit measurements in mice with 99mTc-DTPA-labeled activated charcoal using NanoSPECT-CT

    PubMed Central

    2013-01-01

    Background Gastrointestinal (GI) disorders are commonly associated with chronic conditions such as diabetes, obesity, and hypertension. Direct consequences are obstipation or diarrhea as opposite aspects of the irritable bowel syndrome, and more indirectly, alteration of appetite, feeling of fullness, flatulence, bloatedness, and eventually leading to altered absorption of nutrients. Moreover, GI retention and passage times have been recognized as important factors in determining the release site and hence the bioavailability of orally administered drugs. To facilitate the understanding of physiological and pathological processes involved, it is necessary to monitor the gut motility in animal models. Here, we describe a method for studying the GI transit time using technetium-labeled activated charcoal diethylenetriaminepentaacetic acid (99mTc-Ch-DTPA) detected by single-photon emission computed tomography (SPECT). Methods Tc-DTPA was adsorbed onto activated charcoal and administered orally to trypan blue-tainted (n = 4) 129SvEv mice (50 to 80 MBq/animal, n = 11). The exact distribution and movement of radioactivity in the gastrointestinal tract was measured at intervals of 1, 3, 6, 12, and 22 h by SPECT-CT. In addition, in order to validate the imaging of GI transient time, loperamide (0.25 mg/animal, n = 3) was used to delay the GI transit. Results The transit time measured as the peak radioactivity occurring in the rectum was 6 to 7 h after gavaging of 99mTc-Ch-DTPA. After 1 h, the bolus had passed into the small intestine and entered the cecum and the colon. At 6 and 8 h, the cecum, the ascending, transverse, and descending colon, and the rectum showed significant labeling. Several pellets were stored in the rectum for defecation. After 22 h, little activity remained in the stomach and none was detected in the transverse colon or other GI locations. In contrast, 6 h after administration of loperamide, only the cecum and part of the transverse colon were labeled

  8. The impact of meals on a probiotic during transit through a model of the human upper gastrointestinal tract.

    PubMed

    Tompkins, T A; Mainville, I; Arcand, Y

    2011-12-01

    Commercial literature on various probiotic products suggests that they can be taken before meals, during meals or after meals or even without meals. This has led to serious confusion for the industry and the consumer. The objective of our study was to examine the impact of the time of administration with respect to mealtime and the impact of the buffering capacity of the food on the survival of probiotic microbes during gastrointestinal transit. We used an in vitro Digestive System (IViDiS) model of the upper gastrointestinal tract to examine the survival of a commercial multi-strain probiotic, ProtecFlor®. This product, in a capsule form, contains four different microbes: two lactobacilli (Lactobacillus helveticus R0052 and Lactobacillus rhamnosus R0011), Bifidobacterium longum R0175 and Saccharomyces cerevisiae boulardii. Enumeration during and after transit of the stomach and duodenal models showed that survival of all the bacteria in the product was best when given with a meal or 30 minutes before a meal (cooked oatmeal with milk). Probiotics given 30 minutes after the meal did not survive in high numbers. Survival in milk with 1% milk fat and oatmeal-milk gruel were significantly better than apple juice or spring water. S. boulardii was not affected by time of meal or the buffering capacity of the meal. The protein content of the meal was probably not as important for the survival of the bacteria as the fat content. We conclude that ideally, non-enteric coated bacterial probiotic products should be taken with or just prior to a meal containing some fats.

  9. Perioperative fasting time among cancer patients submitted to gastrointestinal surgeries.

    PubMed

    Pereira, Nayara de Castro; Turrini, Ruth Natalia Teresa; Poveda, Vanessa de Brito

    2017-05-25

    To identify the length of perioperative fasting among patients submitted to gastrointestinal cancer surgeries. Retrospective cohort study, developed by consulting the medical records of 128 patients submitted to gastrointestinal cancer surgeries. The mean of total length of fasting was 107.6 hours. The total length of fasting was significantly associated with the number of symptoms presented before (p=0.000) and after the surgery (p=0.007), the length of hospital stay (p=0.000), blood transfusion (p=0.013), nasogastric tube (p=0.001) and nasojejunal tube (p=0,003), postoperative admission at ICU (p=0.002), postoperative death (p=0.000) and length of preoperative fasting (p=0.000). The length of fasting is associated with complications that affect the quality of the patients' postoperative recovery and nurses' work. The nursing team should be alert to this aspect and being responsible for overseeing the patients' interest, should not permit the unnecessary extension of fasting. Identificar la duración del ayuno perioperatorio entre los pacientes sometidos a cirugías de cáncer gastrointestinal. Estudio de cohorte retrospectivo, por consulta de los registros médicos de 128 pacientes sometidos a cirugías de cáncer gastrointestinal. La media de la duración total del ayuno fue de 107,6 horas. La duración total del ayuno se asoció significativamente con el número de síntomas presentados antes (p=0,000) y después de la cirugía (p=0,007), la duración de la estancia hospitalaria (p=0,000), transfusión de sangre (p=0,013),tubo nasogástrico (P=0,003), ingreso postoperatorio en la UCI (p=0,002), muerte postoperatoria (p=0,000) y duración del ayuno preoperatorio (p=0,000). La duración del ayuno se asocia con complicaciones que afectan la calidad de la recuperación postoperatoria de los pacientes y el trabajo de enfermería. El equipo de enfermería debe estar alerta en relación a este aspecto y ser responsable de supervisar el interés de los pacientes, no

  10. A new high-content model system for studies of gastrointestinal transit: the zebrafish.

    PubMed

    Rich, A

    2009-03-01

    The zebrafish gastrointestinal (GI) tract displays an anatomy and cellular architecture that is similar to the human GI tract, with concentric layers of inner epithelia, connective tissue, circular muscle and outer longitudinal muscle layers. Propulsion of luminal content results from the integrated activity of smooth muscle cells, enteric neurons and the interstitial cells of Cajal (ICC). Zebrafish larvae are transparent and propagating contractions in the entire GI tract are easily visualized. A new moderate-throughput zebrafish-based GI transit assay is described in this issue of Neurogastroenterology and Motility. This assay utilizes intact zebrafish larvae which contain essential regulatory elements (ICC and enteric neurons). Forward genetic analysis, which identifies genes underlying specific phenotypes, is possible using the zebrafish system. The zebrafish model system compliments existing models for studies of GI motility and will contribute to the understanding of the regulation of GI motility, and to identification of novel drug targets.

  11. Quantification of FITC-labelled probiotic Lactobacillus salivarius DSPV 001P during gastrointestinal transit in broilers.

    PubMed

    Blajman, J E; Astesana, D M; Zimmermann, J A; Rossler, E; Scharpen, A Romero; Berisvil, A P; Zbrun, M V; Soto, L P; Rosmini, M R; Frizzo, L S

    2017-02-07

    The knowledge related to the fate of probiotics in the complex environment of the intestinal microbiota in broilers is just beginning to be elucidated; however, it is not yet well understood. A good method to investigate the mechanisms by which probiotics mediate their effects is to mark probiotic bacteria and trace them. The aim of this research was to develop a new method to estimate in vivo fluorescein isothiocyanate (FITC)-labelled Lactobacillus salivarius DSPV 001P counts during passage through the gastrointestinal tract (GIT) of broilers. Forty-five, 1 d old Cobb broilers were used in this trial. Programmed necropsies were performed 30 min, 6 h, and 12 h after the administration of the probiotic bacterium, and samples of liver, crop, duodenum, caecum, and bursa of fabricius were collected. To determine the spatial and temporal transit of L. salivarius DSPV 001P in broilers, the number of bacteria as well as its respective fluorescent signal produced by FITC were measured. In order to observe the relationship between the variables, a logistic regression analysis was applied. The amount of fluorescence could be used as an indicator of fluorescent probiotic bacteria in the crop and duodenum 30 min after probiotic bacterium supplementation. In addition, the fluorescent signal could be used to estimate bacterial counts in caecum 6 and 12 h after L. salivarius DSPV 001P administration. To the best of our knowledge, this research is the first in vivo trial to employ the bacterial FITC-labelling technique in order to enumerate probiotic bacteria during gastrointestinal transit in broilers.

  12. Gastric transit and small intestinal transit time and motility assessed by a magnet tracking system

    PubMed Central

    2011-01-01

    Background Tracking an ingested magnet by the Magnet Tracking System MTS-1 (Motilis, Lausanne, Switzerland) is an easy and minimally-invasive method to assess gastrointestinal transit. The aim was to test the validity of MTS-1 for assessment of gastric transit time and small intestinal transit time, and to illustrate transit patterns detected by the system. Methods A small magnet was ingested and tracked by an external matrix of 16 magnetic field sensors (4 × 4) giving a position defined by 5 coordinates (position: x, y, z, and angle: θ, ϕ). Eight healthy subjects were each investigated three times: (1) with a small magnet mounted on a capsule endoscope (PillCam); (2) with the magnet alone and the small intestine in the fasting state; and (3) with the magnet alone and the small intestine in the postprandial state. Results Experiment (1) showed good agreement and no systematic differences between MTS-1 and capsule endoscopy when assessing gastric transit (median difference 1 min; range: 0-6 min) and small intestinal transit time (median difference 0.5 min; range: 0-52 min). Comparing experiments (1) and (2) there were no systematic differences in gastric transit or small intestinal transit when using the magnet-PillCam unit and the much smaller magnetic pill. In experiments (2) and (3), short bursts of very fast movements lasting less than 5% of the time accounted for more than half the distance covered during the first two hours in the small intestine, irrespective of whether the small intestine was in the fasting or postprandial state. The mean contraction frequency in the small intestine was significantly lower in the fasting state than in the postprandial state (9.90 min-1 vs. 10.53 min-1) (p = 0.03). Conclusion MTS-1 is reliable for determination of gastric transit and small intestinal transit time. It is possible to distinguish between the mean contraction frequency of small intestine in the fasting state and in the postprandial state. PMID:22206545

  13. Effects of fiber on digestibility and transit time in dogs.

    PubMed

    Burrows, C F; Kronfeld, D S; Banta, C A; Merritt, A M

    1982-09-01

    This study examines effects of variations in fiber content on nutrient assimilation, fecal output, and gastrointestinal transit time in the dog. Four normal Beagles were fed four diets in a randomized block design. The basal diet was a canned, balanced, meat-based dog food (Alpo Trio) to which added 3, 6, and 9% by weight of alpha cellulose (Solka Flok). Food intake and fecal outputs were recorded for 5-day periods. Samples of diets and fecal collections were analyzed for dry matter, nitrogen, fat, carbohydrate and ash; digestibilities were calculated. Transit times were measured by a radiographic marker technique. Fecal weight and water increased linearly; digestibility of dry matter decreased from 90 to 70% and ash from 43 to 32% with added fiber. Responses of protein, carbohydrate and fat were less pronounced but were regular; regressions of their digestibilities on added fiber were significant. Regression estimate of true digestibility for alpha-cellulose was 6%. Intestinal transit time decreased from a mean of 37.4 to 28.7 hours with added fiber. Decreased intestinal time would contribute to depression of fry matter digestibility. Increased fecal water output probably also reflected retention by fiber.

  14. An Exoplanet Radius and Transit Timing Survey

    NASA Astrophysics Data System (ADS)

    Deming, Drake; Jennings, Jonald; Sada, Pedro

    2009-08-01

    Many exoplanet systems contain Jupiter-mass planets on close-in orbits. Theories of planetary system formation account for these hot Jupiters as being end states of inward migration. Variants of those theories also predict terrestrial planets to be captured in mean motion resonance with the hot Jupiters. A recent explosion of discoveries by transit surveys have given us a sample of 37 hot Jupiters transiting planets brighter than V=13. A transit timing survey of these systems could detect hot Earths in resonance, via the large (~ 180 second) perturbations they induce on the giant planet transits. Moreover, the discovery photometry for these systems usually provides only relatively coarse photometric precision, but larger-aperture follow-up can determine the giant planet radius to a precision limited only by knowledge of the stellar mass, and thereby reveal the diversity of giant exoplanet structure, such as the presence of heavy element cores. The relatively large sample now available means that a radius- and transit timing-survey is well matched to classical observing and telescope scheduling. We propose continued observations to perform transit photometry using FLAMINGOS on the 2.1-meter in the J-band, where stellar limb darkening is minimal and transit photometry has excellent sensitivity to planetary radii and shifts in transit time.

  15. An Exoplanet Radius and Transit Timing Survey

    NASA Astrophysics Data System (ADS)

    Deming, Drake; Jennings, Jonald; Sada, Pedro

    2010-02-01

    Many exoplanet systems contain Jupiter-mass planets on close-in orbits. Theories of planetary system formation account for these hot Jupiters as being end states of inward migration. Variants of those theories also predict terrestrial planets to be captured in mean motion resonance with the hot Jupiters. A continuing explosion of discoveries by transit surveys have given us a sample of 45 hot Jupiters transiting planets brighter than V=13. A transit timing survey of these systems could detect hot Earths in resonance, via the large (~ 180 second) perturbations they induce on the giant planet transits. Moreover, the discovery photometry for these systems usually provides only relatively coarse photometric precision, but larger-aperture follow-up can determine the giant planet radius to a precision limited only by knowledge of the stellar mass, and thereby reveal the diversity of giant exoplanet structure, such as the presence of heavy element cores. The relatively large sample now available means that a radius- and transit timing-survey is well matched to classical observing and telescope scheduling. We propose continued observations to perform transit photometry using FLAMINGOS on the 2.1-meter in the J-band, where stellar limb darkening is minimal and transit photometry has excellent sensitivity to planetary radii and shifts in transit time.

  16. Decreasing Transition Times in a Second Grade Classroom: Scientific Support for the Timely Transitions Game

    ERIC Educational Resources Information Center

    Yarrough, Jamie L.; Skinner, Christopher H.; Lee, Young Ju; Lemmons, Cathy

    2004-01-01

    Campbell and Skinner used an A-B design to evaluate the effects of the Timely Transitions Game (TTG) on room-to-room transitions in a sixth-grade classroom. The TTG incorporated explicit timing, publicly posted feedback, and an interdependent group contingency with randomly selected transitions and criteria. The purpose of the current study was to…

  17. Magnetic transit-time flowmeter

    DOEpatents

    Forster, George A.

    1976-07-06

    The flow rate of a conducting fluid in a stream is determined by disposing two permanent-magnet flowmeters in the stream, one downstream of the other. Flow of the conducting fluid causes the generation of both d-c and a-c electrical signals, the a-c comprising flow noise. Measurement of the time delay between similarities in the a-c signals by cross-correlation methods provides a measure of the rate of flow of the fluid.

  18. Aurora kinase A in gastrointestinal cancers: time to target.

    PubMed

    Katsha, Ahmed; Belkhiri, Abbes; Goff, Laura; El-Rifai, Wael

    2015-05-20

    Gastrointestinal (GI) cancers are a major cause of cancer-related deaths. During the last two decades, several studies have shown amplification and overexpression of Aurora kinase A (AURKA) in several GI malignancies. These studies demonstrated that AURKA not only plays a role in regulating cell cycle and mitosis, but also regulates a number of key oncogenic signaling pathways. Although AURKA inhibitors have moved to phase III clinical trials in lymphomas, there has been slower progress in GI cancers and solid tumors. Ongoing clinical trials testing AURKA inhibitors as a single agent or in combination with conventional chemotherapies are expected to provide important clinical information for targeting AURKA in GI cancers. It is, therefore, imperative to consider investigations of molecular determinants of response and resistance to this class of inhibitors. This will improve evaluation of the efficacy of these drugs and establish biomarker based strategies for enrollment into clinical trials, which hold the future direction for personalized cancer therapy. In this review, we will discuss the available data on AURKA in GI cancers. We will also summarize the major AURKA inhibitors that have been developed and tested in pre-clinical and clinical settings.

  19. [Advances on the effects of the compounds of a phytotherapic agent (COLIMIL) on upper gastrointestinal transit in mice].

    PubMed

    Savino, F; Capasso, R; Palumeri, E; Tarasco, V; Locatelli, E; Capasso, F

    2008-06-01

    Phytotherapic agents, such as herbal formulations containing Matricariae recutita flowers (chamomile) extract, Foeniculum vulgare fruit (fennel) extract and Melissa officinalis aerial parts (lemon balm) extract have beneficial effects on gastrointestinal tract in colicky infants. However, the mechanism is largely unexplored and, particularly, it is not clear if it affects intestinal motility. The aim of this experimental study was to evaluate the effect of different herbal formulations containing Matricariae recutita extract, Foeniculum vulgare extract and Melissa officinalis extract on upper gastrointestinal transit in mice in vivo. Gastrointestinal transit was measured in male ICR mice and in croton oil-treated mice after the oral administration of herbal formulations containing chamomile, fennel and lemon balm (ColiMil) and chamomile and lemon balm (ColiMil experimental). The herbal formulations tested (0.4-0.8 mL/mouse) dose-dependently and significantly inhibited gastrointestinal transit both in control and in croton oil-treated mice. Chamomile extract and lemon balm extract reduced significantly intestinal motility, but not fennel. At similar concentration ColiMil evoked a more consistent response than ColiMil experimental. Our findings directly demonstrate in vivo the effect of a combination of herbal formulations on intestinal motility. The observed inhibitory effect might be studied with clinical studies to test the efficacy of these compounds in the treatment of colicky infants.

  20. Effect of a selective chloride channel activator, lubiprostone, on gastrointestinal transit, gastric sensory, and motor functions in healthy volunteers.

    PubMed

    Camilleri, Michael; Bharucha, Adil E; Ueno, Ryuji; Burton, Duane; Thomforde, George M; Baxter, Kari; McKinzie, Sanna; Zinsmeister, Alan R

    2006-05-01

    Chloride channels modulate gastrointestinal neuromuscular functions in vitro. Lubiprostone, a selective type 2 chloride channel (ClC-2) activator, induces intestinal secretion and has been shown to relieve constipation in clinical trials; however, the effects of lubiprostone on gastric function and whole gut transit in humans are unclear. Our aim was to compare the effects of the selective ClC-2 activator lubiprostone on maximum tolerated volume (MTV) of a meal, postprandial symptoms, gastric volumes, and gastrointestinal and colonic transit in humans. We performed a randomized, parallel-group, double-blind, placebo-controlled study evaluating the effects of lubiprostone (24 microg bid) in 30 healthy volunteers. Validated methods were used: scintigraphic gastrointestinal and colonic transit, SPECT to measure gastric volumes, and the nutrient drink ("satiation") test to measure MTV and postprandial symptoms. Lubiprostone accelerated small bowel and colonic transit, increased fasting gastric volume, and retarded gastric emptying. MTV values were reduced compared with placebo; however, the MTV was within the normal range for healthy adults in 13 of 14 participants, and there was no significant change compared with baseline measurements. Lubiprostone had no significant effect on postprandial gastric volume or aggregate symptoms but did decrease fullness 30 min after the fully satiating meal. Thus the ClC-2 activator lubiprostone accelerates small intestinal and colonic transit, which confers potential in the treatment of constipation.

  1. Late-time cosmological phase transitions

    NASA Technical Reports Server (NTRS)

    Schramm, David N.

    1991-01-01

    It is shown that the potential galaxy formation and large scale structure problems of objects existing at high redshifts (Z approx. greater than 5), structures existing on scales of 100 M pc as well as velocity flows on such scales, and minimal microwave anisotropies ((Delta)T/T) (approx. less than 10(exp -5)) can be solved if the seeds needed to generate structure form in a vacuum phase transition after decoupling. It is argued that the basic physics of such a phase transition is no more exotic than that utilized in the more traditional GUT scale phase transitions, and that, just as in the GUT case, significant random Gaussian fluctuations and/or topological defects can form. Scale lengths of approx. 100 M pc for large scale structure as well as approx. 1 M pc for galaxy formation occur naturally. Possible support for new physics that might be associated with such a late-time transition comes from the preliminary results of the SAGE solar neutrino experiment, implying neutrino flavor mixing with values similar to those required for a late-time transition. It is also noted that a see-saw model for the neutrino masses might also imply a tau neutrino mass that is an ideal hot dark matter candidate. However, in general either hot or cold dark matter can be consistent with a late-time transition.

  2. Late-time cosmological phase transitions

    SciTech Connect

    Schramm, D.N. Fermi National Accelerator Lab., Batavia, IL )

    1990-11-01

    It is shown that the potential galaxy formation and large-scale structure problems of objects existing at high redshifts (Z {approx gt} 5), structures existing on scales of 100M pc as well as velocity flows on such scales, and minimal microwave anisotropies ({Delta}T/T) {approx lt} 10{sup {minus}5} can be solved if the seeds needed to generate structure form in a vacuum phase transition after decoupling. It is argued that the basic physics of such a phase transition is no more exotic than that utilized in the more traditional GUT scale phase transitions, and that, just as in the GUT case, significant random gaussian fluctuations and/or topological defects can form. Scale lengths of {approximately}100M pc for large-scale structure as well as {approximately}1 M pc for galaxy formation occur naturally. Possible support for new physics that might be associated with such a late-time transition comes from the preliminary results of the SAGE solar neutrino experiment, implying neutrino flavor mixing with values similar to those required for a late-time transition. It is also noted that a see-saw model for the neutrino masses might also imply a tau neutrino mass that is an ideal hot dark matter candidate. However, in general either hot or cold dark matter can be consistent with a late-time transition. 47 refs., 2 figs.

  3. Slope Transit Time (STT): A Pulse Transit Time Proxy requiring Only a Single Signal Fiducial Point.

    PubMed

    Addison, Paul S

    2016-11-01

    A novel pulse transit time proxy measurement, slope transit time (STT), is proposed in this letter. STT is based on geometrical considerations of the arriving photoplethysmographic cardiac waveform and its computation requires only the measurement of a single point on each cardiac beat arriving at the peripheral site. This novel transit time is explained conceptually and its implementation illustrated through its application to signals from respiratory effort, Müller maneuver, and obstructive sleep apnea trials.

  4. Regional gastrointestinal transit and pH studied in 215 healthy volunteers using the wireless motility capsule: influence of age, gender, study country and testing protocol.

    PubMed

    Wang, Y T; Mohammed, S D; Farmer, A D; Wang, D; Zarate, N; Hobson, A R; Hellström, P M; Semler, J R; Kuo, B; Rao, S S; Hasler, W L; Camilleri, M; Scott, S M

    2015-09-01

    The wireless motility capsule (WMC) offers the ability to investigate luminal gastrointestinal (GI) physiology in a minimally invasive manner. To investigate the effect of testing protocol, gender, age and study country on regional GI transit times and associated pH values using the WMC. Regional GI transit times and pH values were determined in 215 healthy volunteers from USA and Sweden studied using the WMC over a 6.5-year period. The effects of test protocol, gender, age and study country were examined. For GI transit times, testing protocol was associated with differences in gastric emptying time (GET; shorter with protocol 2 (motility capsule ingested immediately after meal) vs. protocol 1 (motility capsule immediately before): median difference: 52 min, P = 0.0063) and colonic transit time (CTT; longer with protocol 2: median 140 min, P = 0.0189), but had no overall effect on whole gut transit time. Females had longer GET (by median 17 min, P = 0.0307), and also longer CTT by (104 min, P = 0.0285) and whole gut transit time by (263 min, P = 0.0077). Increasing age was associated with shorter small bowel transit time (P = 0.002), and study country also influenced small bowel and CTTs. Whole gut and CTTs showed clustering of data at values separated by 24 h, suggesting that describing these measures as continuous variables is invalid. Testing protocol, gender and study country also significantly influenced pH values. Regional GI transit times and pH values, delineated using the wireless motility capsule (WMC), vary based on testing protocol, gender, age and country. Standardisation of testing is crucial for cross-referencing in clinical practice and future research. © 2015 John Wiley & Sons Ltd.

  5. Gastrointestinal transit in nonobese diabetic mouse: an animal model of human diabetes type 1.

    PubMed

    El-Salhy, M

    2001-01-01

    Gastrointestinal transit (GI) in the nonobese diabetic (NOD) mouse, an animal model of human diabetes type 1, was examined in animals with short- (duration 1-5 days) and long-term (duration 28-35 days) diabetes. Blood glucose level, serum insulin concentration, and gut neuroendocrine peptide content were also measured. GI was significantly rapid in NOD mice with long-term diabetes (LTD), but was not correlated with blood glucose level, serum insulin concentration, or pancreatic insulin content. GI was correlated with duodenal secretin content, but not with the content of other neuroendocrine peptides in the different segments investigated. Whereas antral vasoactive intestinal peptide (VIP) content in NOD mice with LTD was significantly higher, colonic VIP was lower in NOD mice with short-term diabetes (STD). In the duodenum, whereas the concentration of secretin in NOD mice with both STD and LTD was lower, the gastrin content was higher. Duodenal somatostatin content in NOD mice with LTD was lower. In colon, the content of galanin in NOD mice with LTD was higher than in controls. The decreased content of secretin may be among the factors that cause rapid GI in NOD mice with LTD. Changes in the antral content of VIP, duodenal somatostatin, and colonic galanin in NOD mice with LTD may cause low intestinal secretion and, together with rapid GI, give rise to diarrhoea, which is a common symptom in diabetes.

  6. Transition Path Time Distribution, Tunneling Times, Friction, and Uncertainty

    NASA Astrophysics Data System (ADS)

    Pollak, Eli

    2017-02-01

    A quantum mechanical transition path time probability distribution is formulated and its properties are studied using a parabolic barrier potential model. The average transit time is well defined and readily calculated. It is smaller than the analogous classical mechanical average transit time, vanishing at the crossover temperature. It provides a direct route for determining tunneling times. The average time may be also used to define a coarse grained momentum of the system for the passage from one side of the barrier to the other. The product of the uncertainty in this coarse grained momentum with the uncertainty in the location of the particle is shown under certain conditions to be smaller than the ℏ/2 formal uncertainty limit. The model is generalized to include friction in the form of a bilinear interaction with a harmonic bath. Using an Ohmic friction model one finds that increasing the friction, increases the transition time. Only moderate values of the reduced friction coefficient are needed for the quantum transition time and coarse grained uncertainty to approach the classical limit which is smaller than ℏ/2 when the friction is not too small. These results show how one obtains classical dynamics from a pure quantum system without invoking any further assumptions, approximations, or postulates.

  7. Transition Path Time Distribution, Tunneling Times, Friction, and Uncertainty.

    PubMed

    Pollak, Eli

    2017-02-17

    A quantum mechanical transition path time probability distribution is formulated and its properties are studied using a parabolic barrier potential model. The average transit time is well defined and readily calculated. It is smaller than the analogous classical mechanical average transit time, vanishing at the crossover temperature. It provides a direct route for determining tunneling times. The average time may be also used to define a coarse grained momentum of the system for the passage from one side of the barrier to the other. The product of the uncertainty in this coarse grained momentum with the uncertainty in the location of the particle is shown under certain conditions to be smaller than the ℏ/2 formal uncertainty limit. The model is generalized to include friction in the form of a bilinear interaction with a harmonic bath. Using an Ohmic friction model one finds that increasing the friction, increases the transition time. Only moderate values of the reduced friction coefficient are needed for the quantum transition time and coarse grained uncertainty to approach the classical limit which is smaller than ℏ/2 when the friction is not too small. These results show how one obtains classical dynamics from a pure quantum system without invoking any further assumptions, approximations, or postulates.

  8. Model of rapid gastrointestinal transit in dogs: effects of muscarinic antagonists and a nitric oxide synthase inhibitor.

    PubMed

    Chiba, T; Bharucha, A E; Thomforde, G M; Kost, L J; Phillips, S F

    2002-10-01

    Our aims were to establish a canine model of rapid gastrointestinal transit, and to test the effects of muscarinic receptor antagonists (atropine, pirenzepine, AF-DX116, and darifenacin), and an NOS inhibitor, L-nitro-N-arginine (L-NNA) in this model. For gastric emptying and small bowel transit, 99mTc-labelled DTPA were added to a meal of skimmed milk (236 mL) that contained 2.4 g of magnesium hydroxide. Regional colonic transit was measured by111In-labelled beads placed in a capsule that released isotope in the proximal colon. Scintiscans were taken at regular intervals and indices of transit were calculated. Drugs were administrated intravenously. Gastric emptying, small bowel and colonic transit were rapid. Atropine and darifenacin (a selective M3 antagonist) delayed gastric emptying and colonic transit, the selective M1 and M2 muscarinic antagonists did not. The muscarinic blockers did not slow small bowel transit. L-NNA delayed small bowel and colonic transit but did not slow gastric emptying. A model suitable for the preclinical study of antidiarrhoeals was established. M3 receptors are important in the control of gastric emptying and colonic transit, and NOS inhibition slowed small bowel and colonic transit.

  9. Taking the Time out of Transitions

    ERIC Educational Resources Information Center

    Guardino, Caroline; Fullerton, Elizabeth Kirby

    2014-01-01

    Until now, studies have not looked at the importance of managing and reducing academic transition times in inclusion classrooms. In the present study, researchers examine the impact of teacher-approved, environmental modifications in the context of an inclusion class. The methodology used was a single-subject, multiple baseline design across four…

  10. Microcatheter Embolization of Lower Gastrointestinal Hemorrhage: An Old Idea Whose Time Has Come

    SciTech Connect

    Funaki, Brian

    2004-11-15

    Early attempts of using embolization for lower gastrointestinal hemorrhage were fraught with complications, most notably ischemic colitis or bowel infarction. Embolotherapy was eventually abandoned in favor of catheter-directed vasoconstriction (i.e., vasopressin infusion). This latter therapy is time and labor intensive. With the advent of microcatheter technology, superselective embolization emerged and is rapidly becoming the endovascular therapy of choice for patients with severe lower gastrointestinal hemorrhage refractory to medical management. Numerous studies on the subject have consistently reported high clinical success with low ischemic complications. This article will review the current status of co-axial microcatheter embolization with an emphasis on the technical aspects of the procedure.

  11. Correlation of ibuprofen bioavailability with gastrointestinal transit by scintigraphic monitoring of /sup 171/Er-labeled sustained-release tablets

    SciTech Connect

    Parr, A.F.; Beihn, R.M.; Franz, R.M.; Szpunar, G.J.; Jay, M.

    1987-12-01

    External gamma scintigraphy was used to monitor the gastrointestinal (GI) transit of radiolabeled sustained-release tablets containing 800 mg ibuprofen in eight fasted healthy volunteers. Ibuprofen serum concentrations were determined from blood samples drawn sequentially over a 24-hr period. Serum concentrations and related parameters were correlated to the position of the dosage form in the GI tract from the scintiphotos. The sustained-release tablets were radiolabeled intact utilizing a neutron activation procedure, by incorporating 0.18% of /sup 170/Er2O3 (enriched to greater than 96% /sup 170/Er) into the bulk formulation. After manufacture of the final dosage forms, the tablets were irradiated in a neutron flux (4.4 x 10(13) n/cm2.sec) for 2 min, converting the stable /sup 170/Er to radioactive /sup 171/Er (t1/2 = 7.5 hr). Each tablet contained 50 microCi of /sup 171/Er at the time of administration. The scintigraphy studies suggested that the greatest proportion of ibuprofen was absorbed from this dosage form while the tablet was in the large bowel. The dosage forms eroded slowly in the small bowel and appeared to lose their integrity in the large bowel. In vitro studies showed only minimal effects of the neutron irradiation procedure on the dosage form performance.

  12. Potential role of fecal microbiota from patients with slow transit constipation in the regulation of gastrointestinal motility.

    PubMed

    Ge, Xiaolong; Zhao, Wei; Ding, Chao; Tian, Hongliang; Xu, Lizhi; Wang, Hongkan; Ni, Ling; Jiang, Jun; Gong, Jianfeng; Zhu, Weiming; Zhu, Minsheng; Li, Ning

    2017-03-27

    The gut microbiota is involved in various physiological functions, and disturbances in the host-microbiome have been proven to contribute to the dysfunction of gut; however, whether microbiota participates in the pathogenesis of constipation remains unclear. In this study, we extracted and analyzed microbiota in feces from constipated donors who had undergone effective therapy with fecal microbiota transplantation, transplanted microbiota into pseudo-germ-free mice, and measured gut motility. These mice presented with lower pellet frequency and water percentage, smaller pellet size, delayed gastrointestinal transit time, and weaker spontaneous contractions of colonic smooth muscle. To determine the mechanism underlying delayed gut motility, microbial metabolites were measured. Short chain fatty acids and secondary bile acids were decreased in mice receiving microbiota from constipated donors. Moreover, the compositional changes of gut microbiota in constipated patients were identified, including the operational taxonomic unit, and the species richness and α diversity were much greater than those in healthy volunteers. These findings suggest that alterations of the microbiome might affect gut motility via altered microbial-derived metabolites in the development of constipation, and the restoration of disturbed microbiota might improve the clinical phenotype. This study indicates that regulating the intestinal environment may be a novel therapy strategy for constipation.

  13. Effect of jejunal infusion of nutrients on gastrointestinal transit and hormonal response in man.

    PubMed

    Vidon, N; Pfeiffer, A; Chayvialle, J A; Merite, F; Maurel, M; Franchisseur, C; Huchet, B; Bernier, J J

    1989-12-01

    The effects of jejunal infusion of nutrients on gastric emptying and secretion, intestinal transit and hormone release were studied in human volunteers. Two caloric loads, 1.3 and 3.3 kcal/min, of a nutrient solution consisting of 18 percent protein, 27 percent lipids, and 55 percent carbohydrates were tested. These were first used in random order in 6 subjects to assess the effects on intestinal transit. For the study of gastric emptying, jejunal infusion was started 1 h after intragastric instillation of a 490 kcal, 400 ml, homogenized meal. Intestinal transit time and gastric emptying half-time increased with the rate of nutrient infusion into the jejunum. Postprandial gastric secretion was reduced. The two caloric loads induced significant rises of plasma cholecystokinin and gastric inhibitory polypeptide concentrations. Plasma motilin decreased in relation to the jejunal caloric load. The other peptides were essentially not affected by jejunal nutrient infusion in fasting subjects. We conclude that in man, gastric emptying rate, gastric secretion, and intestinal transit are regulated by the presence of nutrients in the jejunum.

  14. Detection of intestinal protozoa in paediatric patients with gastrointestinal symptoms by multiplex real-time PCR.

    PubMed

    Maas, L; Dorigo-Zetsma, J W; de Groot, C J; Bouter, S; Plötz, F B; van Ewijk, B E

    2014-06-01

    The performance of a multiplex real-time PCR for the detection of Blastocystis, Dientamoeba fragilis, Giardia lamblia, Cryptosporidium species and Entamoeba species in faecal samples was evaluated in an observational prospective study. Paediatric patients (0-18 years) presenting with gastrointestinal symptoms and suspected of having enteroparasitic disease were included. A questionnaire on gastrointestinal symptoms and the chosen treatment was completed at the start of the study and after 6 weeks. Of 163 paediatric patients (mean age, 7.8 years), 114 (70%) had a PCR-positive faecal sample. D. fragilis was detected most frequently, in 101 patients, followed by Blastocystis in 49. In faecal samples of 47 patients, more than one protozoan was detected, mainly the combination of D. fragilis and Blastocystis. Reported gastrointestinal symptoms were abdominal pain (78%), nausea (30%), and altered bowel habits (28%). Eighty-nine of the PCR-positive patients were treated with antibiotics. A significant reduction in abdominal pain was observed both in treated and in untreated patients. This study demonstrated that multiplex real-time PCR detects a high percentage of intestinal protozoa in paediatric patients with gastrointestinal symptoms. However, interpretation and determination of the clinical relevance of a positive PCR result in this population are still difficult. © 2013 The Authors Clinical Microbiology and Infection © 2013 European Society of Clinical Microbiology and Infectious Diseases.

  15. Effect of type of grain and feed processing on gastrointestinal retention times in horses.

    PubMed

    Rosenfeld, I; Austbø, D

    2009-12-01

    Gastrointestinal retention time may affect digestive processes in the horse. To evaluate the effect of processing of grains on mean retention time in different segments of the gastrointestinal tract, 4 Norwegian Cold-blooded trotters (cecally cannulated, approximately 500 kg of BW) were used. Barley, maize, and wheat were all ground, pelleted, extruded, and micronized to create a total of 12 processed grains. After an adaptation period of 5 d, each horse was given 0.2 kg of Yb-mordanted grain together with their morning meal, which consisted of 2 kg of hay and 1 kg of one of the grains. Fecal samples were collected 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 48, and 52 h after administration of the marker dose. The samples were analyzed for Yb, and values were used for a 2-compartment nonlinear passage model to calculate the retention times in different segments of the gastrointestinal tract for each type of grain and each processing method. Among grains, maize had a longer retention time in the time-dependent compartment (believed to be cecum) than barley and wheat (P < 0.05) and hence a decreased passage rate out of this compartment (P < 0.05). For the feed processing treatment, ground grains had a longer compartmental retention time than those grains processed with the high temperature (extruded and micronized; P < 0.05), but the total mean retention time was not affected by treatments. In conclusion, feed processing affected passage rates and compartmental retention times, but did not affect the overall retention time in the gastrointestinal tract of the horse.

  16. Linking age, survival, and transit time distributions

    NASA Astrophysics Data System (ADS)

    Calabrese, Salvatore; Porporato, Amilcare

    2015-10-01

    Although the concepts of age, survival, and transit time have been widely used in many fields, including population dynamics, chemical engineering, and hydrology, a comprehensive mathematical framework is still missing. Here we discuss several relationships among these quantities by starting from the evolution equation for the joint distribution of age and survival, from which the equations for age and survival time readily follow. It also becomes apparent how the statistical dependence between age and survival is directly related to either the age dependence of the loss function or the survival-time dependence of the input function. The solution of the joint distribution equation also allows us to obtain the relationships between the age at exit (or death) and the survival time at input (or birth), as well as to stress the symmetries of the various distributions under time reversal. The transit time is then obtained as a sum of the age and survival time, and its properties are discussed along with the general relationships between their mean values. The special case of steady state case is analyzed in detail. Some examples, inspired by hydrologic applications, are presented to illustrate the theory with the specific results. This article was corrected on 11 Nov 2015. See the end of the full text for details.

  17. Mangiferin, a natural xanthone, accelerates gastrointestinal transit in mice involving cholinergic mechanism

    PubMed Central

    Morais, Talita Cavalcante; Lopes, Synara Cavalcante; Carvalho, Karine Maria Martins Bezerra; Arruda, Bruno Rodrigues; de Souza, Francisco Thiago Correia; Trevisan, Maria Teresa Salles; Rao, Vietla Satyanarayana; Santos, Flávia Almeida

    2012-01-01

    AIM: To investigate the effects of mangiferin on gastrointestinal transit (GIT) in normal and constipated mice, together with the possible mechanism. METHODS: Intragastrically-administered charcoal meal was used to measure GIT in overnight starved Swiss mice. In the first experiments, mangiferin (3 mg/kg, 10 mg/kg, 30 mg/kg, and 100 mg/kg, po) or tegaserod (1 mg/kg, ip) were administered 30 min before the charcoal meal to study their effects on normal transit. In the second series, mangiferin (30 mg/kg) was tested on delayed GIT induced by several different pharmacological agonists (morphine, clonidine, capsaicin) or antagonists (ondansetron, verapamil, and atropine) whereas in the third series, mangiferin (30 mg/kg, 100 mg/kg and 300 mg/kg) or tegaserod (1 mg/kg) were tested on 6 h fecal pellets outputted by freely fed mice. The ratio of wet to dry weight was calculated and used as a marker of fecal water content. RESULTS: Mangiferin administered orally significantly (P < 0.05) accelerated GIT at 30 mg/kg and 100 mg/kg (89% and 93%, respectively), similarly to 5-hydroxytryptamine4 (5-HT4) agonist tegaserod (81%) when compared to vehicle-treated control (63%). Co-administered mangiferin (30 mg/kg) totally reversed the inhibitory effect of opioid agonist morphine, 5-HT3-receptor antagonist ondansetron and transient receptor potential vanilloid-1 receptor agonist capsaicin on GIT, but only to a partial extent with the GIT-delay induced by α2-adrenoceptor agonist clonidine, and calcium antagonist verapamil. However, co-administered atropine completely blocked the stimulant effect of mangiferin on GIT, suggesting the involvement of muscarinic acetylcholine receptor activation. Although mangiferin significantly enhanced the 6 h fecal output at higher doses (245.5 ± 10.43 mg vs 161.9 ± 10.82 mg and 227.1 ± 20.11 mg vs 161.9 ± 10.82 mg of vehicle-treated control, at 30 and 100 mg/kg, P < 0.05, respectively), the effect of tegaserod was more potent (297.4 ± 7.42 mg

  18. Effect of Food Status on the Gastrointestinal Transit of Amphotericin B-Containing Solid Lipid Nanoparticles in Rats.

    PubMed

    Amekyeh, Hilda; Billa, Nashiru; Yuen, Kah-Hay; Lim, Sheau Chin Sherlyn

    2016-10-01

    Amphotericin B (AmB) is poorly absorbed from the gastrointestinal tract. Recent studies have suggested enhanced drug absorption from solid lipid nanoparticles (SLN). Little is known of the fate of AmB absorption within the gastrointestinal tract, and no gastrointestinal transit study has yet been performed on AmB-containing nano-formulations. We aimed to investigate the effect of food on the gastrointestinal transit properties of an AmB-containing SLN in rats. Three SLNs containing AmB, paracetamol, or sulfasalazine were formulated using cocoa butter and beeswax as lipid matrices and simultaneously administered orally to Sprague-Dawley rats. Paracetamol and sulfapyridine were used as marker drugs for estimating gastric emptying and cecal arrival, respectively. The pharmacokinetic data generated for paracetamol and sulfapyridine were used in estimating the absorption of the AmB SLNs in the small and large intestines, respectively. A delayed rate of AmB absorption was observed in the fed state; however, the extent of absorption was not affected by food. Specifically, the percentages of AmB absorption during the fasted state in the stomach, small intestine, and colon were not significantly different from absorption within the respective regions in the fed state. In both states, however, absorption was highest in the colon and appeared to be a combination of absorption from the small intestine plus absorption proper within the colon. The study suggests that AmB SLN, irrespective of food status, is slowly but predominantly taken up by the lymph, making the small intestine the most favorable site for the delivery of the AmB SLNs.

  19. Evaluation of gastrointestinal transit characteristics of oral patch preparation using caffeine as a model drug in human volunteers.

    PubMed

    Eaimtrakarn, Sudarat; Prasad, Y V Rama; Puthli, Shivanand P; Yoshikawa, Yukako; Shibata, Nobuhito; Takada, Kanji

    2002-01-01

    Salivary caffeine excretion rate test has been proposed for the evaluation of gastrointestinal transit characteristics of an oral patch preparation after administration to human volunteers instead of measuring the plasma or serum concentration in the early stages of formulation development. Patches having a diameter of 3.0 mm and containing caffeine as a model drug were prepared. The patches consisted of 1) the backing layer made of a water-insoluble polymer, 2) the drug-carrying layer composed of caffeine and a gel-forming polymer, and 3) the enteric polymer membrane. These three layer patches were filled into enteric capsules. Caffeine solution in an enteric capsule was used as the control preparation. After oral administration of each preparation to human volunteers at a dose of 50 mg of caffeine in a cross-over study with a wash-out period of two weeks, saliva samples were collected over 1 min at every sampling time for 12 h and salivary caffeine concentration was determined by a HPLC assay method. Salivary caffeine excretion rate (ER) was used for pharmacokinetic analysis. Mean residence time (MRT) and first-appearance time of caffeine into the saliva (T(i)) were determined. To characterize the pharmacokinetics of caffeine, MRT-T(i) values of patch and solution preparations were compared. Patch preparations had a T(i) value of 2.33+/-0.33 h and showed significantly longer MRT-T(i), 3.87+/-0.21 h, as compared to the control preparation (MRT-T(i)=1.04+/-0.38 h) under fasting condition (p<0.05). Food intake prolonged the gastric emptying time (GET) of the preparations with T(i) values of 5.00+/-1.15 h for control preparation and 4.67+/-1.20 h for patch preparation. The MRT-T(i) values were 0.62+/-0.20 h (control) and 2.45+/-0.73 h (patch). The results of this study indicate that the parameter, MRT-T(i), was useful in characterizing the transit characteristics of oral patch preparations than MRT itself and the presence of food affects the performance of the patch

  20. Perturbation of upper gastrointestinal transit and antroduodenal motility by experimentally applied stress: the role of beta-adrenoreceptor mediated pathways.

    PubMed

    O'Brien, J D; Thompson, D G; Day, S J; Burnham, W R; Walker, E

    1989-11-01

    A series of three experiments were performed on healthy adult volunteers to investigate the possible role played by beta-adrenoreceptor mediated pathways in the disturbance of human upper intestinal motor function by hand immersion in cold water. In the first experiment, (an extended pilot study on one individual), orocaecal transit of a standard meal was measured on 36 occasions with and without cold water stimulation and with and without a series of alpha and beta blocking drugs. Cold water stimulation consistently delayed transit in this individual, an effect which was attenuated by prior beta-blockade. In a double blind trial of the effect of beta-blocker atenolol v placebo on transit in nine individuals, a consistent reduction in the cold water induced transit delay was observed (p less than 0.01) independent of any direct effect of beta-blockade. In the third experiment seven individuals underwent repeated studies of antroduodenal pressure activity comparing the effects of cold and warm water stimulation with and without beta blockade to determine whether the observed transit effect could be related to an action on gastrointestinal motility. Cold water stimulation reduced antroduodenal motility, but no consistent effects of previous beta blockade were noted. These studies indicate the presence of a beta-adrenoreceptor mediated pathway in the cold water induced delay of orocaecal transit but not in the inhibition of gastroduodenal motility. Further studies are indicated to determine the site and mode of action of this transit effect more precisely.

  1. Pharmacokinetic modeling and simulation of gastrointestinal transit effects on plasma concentrations of drugs from mixed immediate-release and enteric-coated pellet formulations.

    PubMed

    Watanalumlerd, Prapoch; Christensen, J Mark; Ayres, James W

    2007-01-01

    Effects of gastrointestinal transit on plasma concentrations of drugs from mixed immediate-release and enteric-coated pellet formulation were simulated with models developed by including gastric emptying time and lag time of emptying. Models were evaluated by comparing simulated plasma concentrations of amphetamine from Monte Carlo simulations to available published data of a commercial mixed pellet formulation (Adderall XR). Results show that the plasma profile from the mixed pellet formulation does not mimic that from two immediate-release doses administered at different times. Instead, the plasma profile from the mixed pellets of amphetamine is similar to a typical sustained-release formulation. The pharmacokinetic models presented herein describe plasma concentrations of amphetamine from mixed pellet formulation quite well. The models and assumptions are general and can be applied to other drugs in similar mixed pellet dosage forms.

  2. Transit Timing Study with Kepler and its synergy with LAMOST

    NASA Astrophysics Data System (ADS)

    Xie, Jiwei; Dong, Subo; Zhu, Zhaohuan; Luo, A.-Li; Zhou, Ji-Lin

    2015-12-01

    Kepler space telescope has found over 4000 transiting planet candidates. Transit timing is a powerful tool to study these transit planet candidates. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST: http://www.lamost.org) provides mass and radius measurements of the stars thus helps with modeling transit timing. Here, we will show two transit timing techniques, i.e., transit timing variation (TTV) and transit duration (TD), which enable confirming their planetary nature and obtaining insight into their orbital properties by combining Kepler and LAMOST.

  3. Transit Timing Variations In Binary Star Systems

    NASA Astrophysics Data System (ADS)

    Sansone, Eric; Haghighipour, N.

    2012-01-01

    We present the results of a study of the effect of a stellar companion on the transit timing variations (TTV) of a planetary system. The purpose of our study is to determine the ranges of the orbital elements of a secondary star for which the amplitude of a currently existing TTV is enhanced. We chose the system of Kepler 9 as this system represents the first planetary system detected by the transit timing variation method, and studied its TTVs by considering a hypothetical secondary star in this system. By varying the mass, semi-major axis, and eccentricity of the fictitious binary companion, we tested the stability of the known planets Kepler-9c and Kepler-9b and identified the region of the parameter-space for which the binary planetary system would be stable. We calculated TTVs for the two planets of the system for different values of the orbital elements of the secondary star and calculated its difference with the system's already existing TTVs. Results of our study indicate that the effect of the binary companion is significant only when the secondary star is in a highly eccentric orbit and/or the planets of the system are within the range of Super-Earth or terrestrial sizes. This work was funded by the National Science Foundation in the form of a Research Experience for Undergraduates program at the University of Hawaii at Manoa.

  4. Catchment Transit Times - Does Scale Matter?

    NASA Astrophysics Data System (ADS)

    Hrachowitz, M.; Soulsby, C.; Tetzlaff, D.; Speed, M.

    2009-12-01

    Mean transit times (MTT) can give useful insights into the internal processes of hydrological systems. However, our understanding of how they vary and scale remains unclear. The objective of this study was therefore to compare MTT at different scales and to thereby identify possible changes in dominant flow pathways and mixing processes over several orders of magnitude from small headwaters to large scale catchments. Furthermore, the study aimed at finding a new way to determine MTT, suitable for application in ungauged catchments. MTTs were estimated using an input weighed convolution integral approach with a Gamma distribution as transit time distribution and weekly δ18O data from 20, mostly nested, contrasting catchments in North-East Scotland ranging from 1 to 1800 km2. The estimated MTTs ranged between 270 and 1172 days and were used to test a previously developed multiple linear regression (MLR) model for MTT prediction based on metrics of soil cover, landscape organization and climate. We show that the controls on MTT identified by the MLR model hold with the independent data from these 20 sites and that the MLR can be used to predict MTT in ungauged montane catchments within a mean relative error of 25 % without the need for independent tracer information. Furthermore, it was found that the dominant controls on MTT not only remain unchanged in regions other than those used for the original calibration of the MLR but also over 3 more orders of magnitude of catchment size, suggesting no major change of dominant flow paths and mixing processes at larger scales. This is consistent with the fact that only the variance of MTT, rather than MTT, showed a scaling relationship above a potential threshold of ~ 50 km2. However, MTT itself appeared to converge with increasing catchment scale, apparently due to the integration of heterogeneous headwater responses in larger downstream catchments.

  5. The serotonin receptor mediates changes in autonomic neurotransmission and gastrointestinal transit induced by heat-killed Lactobacillus brevis SBC8803.

    PubMed

    Horii, Y; Nakakita, Y; Misonou, Y; Nakamura, T; Nagai, K

    2015-01-01

    Lactobacilli exhibit several health benefits in mammals, including humans. Our previous reports established that heat-killed Lactobacillus brevis SBC8803 (SBC8803) increased both efferent gastric vagal nerve activity and afferent intestinal vagal nerve activity in rats. We speculated that this strain could be useful for the treatment of gastrointestinal (GI) disorders. In this study, we examined the effects of SBC8803 on peristalsis and the activity of the efferent celiac vagal nerve innervating the intestine in rats. First, we examined the effects of intraduodenal (ID) administration of SBC8803 on efferent celiac vagal nerve activity (efferent CVNA) in urethane-anesthetised rats using electrophysiological studies. The effects of intravenous injection of the serotonin 5-HT3 receptor antagonist granisetron on changes in efferent CVNA due to ID administration of SBC8803 were also investigated. Finally, the effects of oral gavage of SBC8803 on GI transit were analysed using the charcoal propulsion method in conscious rats treated with or without granisetron. ID administration of SBC8803 increased efferent CVNA. Pretreatment with granisetron eliminated SBC8803-dependent changes in efferent CVNA. Furthermore, oral gavage of SBC8803 significantly accelerated GI transit, while pretreatment with granisetron inhibited GI transit. Our findings suggested that SBC8803 increased efferent CVNA and GI transit of charcoal meal via 5-HT3 receptors. Moreover, SBC8803 enhanced the activity of efferent vagal nerve innervating the intestine and promoted peristalsis via 5-HT3 receptors.

  6. Validation of a Single-Time-Point Measurement of Total Abdominal Counts to Simplify Small Bowel and Colon Transit Analyses.

    PubMed

    Maurer, Alan H; Parupalli, Rahul; Orthey, Perry; Parkman, Henry P

    2016-12-01

    The Society of Nuclear Medicine and Molecular Imaging and European Association of Nuclear Medicine procedure guide on gastrointestinal transit currently indicates that the mean of total abdominal counts of 7 time points (0-360 min) is used to define the total abdominal counts for bowel transit studies. The purpose of this study was to investigate the variability of total abdominal counts during the initial 6 h of bowel transit and to determine whether a simplified, single-time-point measurement can be used.

  7. Glycogen synthase kinase-3 beta regulates Snail and β-catenin expression during Fas-induced epithelial-mesenchymal transition in gastrointestinal cancer.

    PubMed

    Zheng, Haoxuan; Li, Wenjing; Wang, Yadong; Liu, Zhizhong; Cai, Yidong; Xie, Tingting; Shi, Meng; Wang, Zhiqing; Jiang, Bo

    2013-08-01

    Fas signalling has been shown to induce the epithelial-mesenchymal transition (EMT) to promote gastrointestinal (GI) cancer metastasis, but its mechanism of action is still unknown. The effects of Fas-ligand (FasL) treatment and inhibition of Fas signalling on GI cancer cells were tested using invasion assay, immunofluorescence, immunoblot, Reverse Transcription Polymerase Chain Reaction (RT-PCR), quantitative Real-time PCR (qRT-PCR), immunoprecipitation and luciferase reporter assay. Immunohistochemistry was used to analyse the EMT-associated molecules in GI cancer specimens. FasL treatment inhibited E-cadherin transcription by upregulation of Snail in GI cancer cells. The nuclear expression and transcriptional activity of Snail and β-catenin were increased by inhibitory phosphorylation of glycogen synthase kinase-3 beta (GSK-3β) at Ser9 by FasL-induced extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) signalling. Snail associated with β-catenin in the nucleus and, thus, increased β-catenin transcriptional activity. Evaluation of human GI cancer specimens showed that the expression of FasL, phospho-GSK-3β, Snail and β-catenin increase during GI cancer progression. An EMT phenotype was shown to correlate with an advanced cancer stage, and a non-EMT phenotype significantly correlated with a better prognosis. Collectively, these data indicate that GSK-3β regulates Snail and β-catenin expression during Fas-induced EMT in gastrointestinal cancer.

  8. Telemetric real-time sensor for the detection of acute upper gastrointestinal bleeding.

    PubMed

    Schostek, Sebastian; Zimmermann, Melanie; Keller, Jan; Fode, Mario; Melbert, Michael; Schurr, Marc O; Gottwald, Thomas; Prosst, Ruediger L

    2016-04-15

    Acute upper gastrointestinal bleedings from ulcers or esophago-gastric varices are life threatening medical conditions which require immediate endoscopic therapy. Despite successful endoscopic hemostasis, there is a significant risk of rebleeding often requiring close surveillance of these patients in the intensive care unit (ICU). Any time delay to recognize bleeding may lead to a high blood loss and increases the risk of death. A novel telemetric real-time bleeding sensor can help indicate blood in the stomach: the sensor is swallowed to detect active bleeding or is anchored endoscopically on the gastrointestinal wall close to the potential bleeding source. By telemetric communication with an extra-corporeal receiver, information about the bleeding status is displayed. In this study the novel sensor, which measures characteristic optical properties of blood, has been evaluated in an ex-vivo setting to assess its clinical applicability and usability. Human venous blood of different concentrations, various fluids, and liquid food were tested. The LED-based sensor was able to reliably distinguish between concentrated blood and other liquids, especially red-colored fluids. In addition, the spectrometric quality of the small sensor (size: 6.5mm in diameter, 25.5mm in length) was comparable to a much larger and technically more complex laboratory spectrophotometer. The experimental data confirm the capability of a miniaturized sensor to identify concentrated blood, which could help in the very near future the detection of upper gastrointestinal bleeding and to survey high-risk patients for rebleeding. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Gastrointestinal Transit Assessment: Role of Scintigraphy: Where Are We Now? Where Are We Going?

    PubMed

    Ziessman, Harvey A

    2016-12-01

    The diagnostic imaging evaluation of patients with suspected esophagogastrointestinal transit disorders is changing. Anatomical methods, e.g., barium studies, endoscopy, manometry, radiopaque markers, have long been the techniques available and used for diagnosis. The one exception has been gastric emptying, where radionuclide scintigraphy has been the standard for decades. Esophageal transit scintigraphy is an old and reliable methodology but probably underutilized. The diagnostic use of small and large intestinal transit scintigraphy is increasing, in part, because of the limitations of the other methods but, most importantly, because it is truly physiologic, i.e., the transit of radiolabeled food can be imaged and quantified from the mouth to rectum. Limitations to its wider use have been the lack of standardization, general availability, and reimbursement issues. Radionuclide methods are increasingly being used to evaluate esophagogastrointestinal transit in a single study, from top to bottom.

  10. Endoscopic ultrasonography: Transition towards the future of gastro-intestinal diseases

    PubMed Central

    De Lisi, Stefania; Giovannini, Marc

    2016-01-01

    Endoscopic ultrasonography (EUS) is a technique with an established role in the diagnosis and staging of gastro-intestinal tumors. In recent years, the spread of new devices dedicated to tissue sampling has improved the diagnostic accuracy of EUS fine-needle aspiration. The development of EUS-guided drainage of the bilio-pancreatic region and abdominal fluid collections has allowed EUS to evolve into an interventional tool that can replace more invasive procedures. Emerging techniques applying EUS in pancreatic cancer treatment and in celiac neurolysis have been described. Recently, confocal laser endomicroscopy has been applied to EUS as a promising technique for the in vivo histological diagnosis of gastro-intestinal, bilio-pancreatic and lymph node lesions. In this state-of-the-art review, we report the most recent data from the literature regarding EUS devices, interventional EUS, EUS-guided confocal laser endomicroscopy and EUS pancreatic cancer treatment, and we also provide an overview of their principles, clinical applications and limitations. PMID:26855537

  11. Time trends and outcome of gastrointestinal bleeding in the Veneto region: a retrospective population based study from 2001 to 2010.

    PubMed

    Cavallaro, Lucas G; Monica, Fabio; Germanà, Bastianello; Marin, Renato; Sturniolo, Giacomo C; Saia, Mario

    2014-04-01

    Gastrointestinal bleeding is the most frequent emergency for gastroenterologists. Despite advances in management, an improvement in mortality is still not evident. Determining time trends of gastrointestinal bleeding hospitalization and outcomes from 2001 to 2010 in the Veneto Region (Italy). Data of patients admitted with gastrointestinal bleeding from Veneto regional discharge records were retrospectively evaluated. Chi-squared and multivariate logistic regression model were used. Overall, 44,343 patients (mean age 64.2 ± 8.6 years) with gastrointestinal bleeding were analysed: 23,450 (52.9%) had upper, 13,800 (31.1%) lower, and 7093 (16%) undefined gastrointestinal bleeding. Admission rate decreased from 108.0 per 100,000 in 2001 to 80.7 in 2010, mainly owing to a decrease in upper gastrointestinal bleeding (64.4 to 35.9 per 100,000, p<0.05). Reductions in hospital fatality rate (from 5.3% to 3%, p<0.05), length of hospital stay (from 9.3 to 8.7 days, p<0.05), and need for surgery (from 5.6% to 5%, p<0.05) were observed. Surgery (OR: 2.97, 95% CI: 2.59-3.41) and undefined gastrointestinal bleeding (OR: 2.89, 95% CI: 2.62-3.19) were found to be risk factors for mortality. Patient admissions for gastrointestinal bleeding decreased significantly over the years, owing to a decrease in upper gastrointestinal bleeding. Improved outcomes could be related to regional dedicated clinical gastroenterological management. Copyright © 2013 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

  12. Inhibitory Effects of Two Varieties of Tunisian Pomegranate (Punica granatum L.) Extracts on Gastrointestinal Transit in Rat

    PubMed Central

    Souli, Abdelaziz; Sebai, Hichem; Rtibi, Kais; Chehimi, Latifa; Sakly, Mohsen; Amri, Mohamed; El-Benna, Jamel; Marzouki, Lamjed

    2015-01-01

    Abstract The present study was undertaken to determine whether total and methanol juice extracts of two Tunisian Pomegranate (Punica granatum L.) varieties (Garsi and Gabsi) protect against diarrhea as well as their effects on gastrointestinal transit (GIT) in healthy rats. In this respect, male Wistar rats were used and divided into control- and pomegranate-treated groups. The antidiarrheal activity was evaluated using the castor oil-induced diarrhea method and the GIT was assessed using charcoal meal. Our results showed that total and methanol P. granatum juice extracts produced a significant dose-dependent protection against castor oil-induced diarrhea. Pomegranate extracts and juice also decreased the GIT significantly and dose dependently. Importantly, the Garsi variety appeared to be more effective than the Gabsi variety on these two parameters. These findings suggest that pomegranate extracts have a potent antidiarrheal property in rats confirming their efficiency in the Tunisian traditional medicine. PMID:25775227

  13. Examining the gastrointestinal transit of lipid-based liquid crystalline systems using whole-animal imaging.

    PubMed

    Pham, Anna C; Nguyen, Tri-Hung; Nowell, Cameron J; Graham, Bim; Boyd, Ben J

    2015-12-01

    Lipid-based liquid crystalline (LC) systems have the potential to sustain the oral absorption of poorly water-soluble drugs in vivo, facilitating slow drug release from their complex internal structure. To further evaluate the dynamic relationship between gastric retention and sustained drug absorption for these systems, this study aimed to explore non-invasive X-ray micro-CT imaging as an approach to assess gastric retention. Pharmacokinetic studies were also conducted with cinnarizine-loaded LC formulations to correlate gastric retention of the formulation to drug absorption. The in vivo studies demonstrated the interplay between gastric retention and drug absorption based on the digestibility of the LC structures. An increase in non-digestible phytantriol (PHY) composition in the formulation relative to digestible glyceryl monooleate (GMO) increased the gastric retention, with 68 ± 4 % of formulation intensity remaining at 8 h for 85 % w/w PHY, and 26 ± 9 % for 60 % w/w PHY. Interestingly, it was found that PHY 30 % w/w in GMO provided the highest bioavailability for cinnarizine (CZ) amongst the other combinations, including GMO alone. The studies demonstrated that combining digestible and non-digestible lipids into LC systems allowed for an optimal balance between sustaining drug absorption whilst increasing plasma concentration (C max) over time, leading to enhanced oral bioavailability. The results demonstrate the potential for utilising non-invasive X-ray micro-CT imaging to dynamically assess the GI transit of orally administered liquid crystal-forming formulations.

  14. Contemporary meta-analysis of short-term probiotic consumption on gastrointestinal transit

    PubMed Central

    Miller, Larry E; Zimmermann, Angela K; Ouwehand, Arthur C

    2016-01-01

    AIM: To determine the efficacy of probiotic supplementation on intestinal transit time (ITT) in adults and to identify factors that influence these outcomes. METHODS: We conducted a systematic review of randomized controlled trials of probiotic supplementation that measured ITT in adults. Study quality was assessed using the Jadad scale. A random effects meta-analysis was performed with standardized mean difference (SMD) of ITT between probiotic and control groups as the primary outcome. Meta-regression and subgroup analyses examined the impact of moderator variables on SMD of ITT. RESULTS: A total of 15 clinical trials with 17 treatment effects representing 675 subjects were included in this analysis. Probiotic supplementation was moderately efficacious in decreasing ITT compared to control, with an SMD of 0.38 (95%CI: 0.23-0.53, P < 0.001). Subgroup analyses demonstrated statistically greater reductions in ITT with probiotics in subjects with vs without constipation (SMD: 0.57 vs 0.22, P < 0.01) and in studies with high vs low study quality (SMD: 0.45 vs 0.00, P = 0.01). Constipation (R2 = 38%, P < 0.01), higher study quality (R2 = 31%, P = 0.01), older age (R2 = 27%, P = 0.02), higher percentage of female subjects (R2 = 26%, P = 0.02), and fewer probiotic strains (R2 = 20%, P < 0.05) were predictive of decreased ITT with probiotics in meta-regression. Medium to large treatment effects were identified with B. lactis HN019 (SMD: 0.67, P < 0.001) and B. lactis DN-173 010 (SMD: 0.54, P < 0.01) while other probiotic strains yielded negligible reductions in ITT relative to control. CONCLUSION: Probiotic supplementation is moderately efficacious for reducing ITT in adults. Probiotics were most efficacious in constipated subjects, when evaluated in high-quality studies, and with certain probiotic strains. PMID:27275105

  15. Contemporary meta-analysis of short-term probiotic consumption on gastrointestinal transit.

    PubMed

    Miller, Larry E; Zimmermann, Angela K; Ouwehand, Arthur C

    2016-06-07

    To determine the efficacy of probiotic supplementation on intestinal transit time (ITT) in adults and to identify factors that influence these outcomes. We conducted a systematic review of randomized controlled trials of probiotic supplementation that measured ITT in adults. Study quality was assessed using the Jadad scale. A random effects meta-analysis was performed with standardized mean difference (SMD) of ITT between probiotic and control groups as the primary outcome. Meta-regression and subgroup analyses examined the impact of moderator variables on SMD of ITT. A total of 15 clinical trials with 17 treatment effects representing 675 subjects were included in this analysis. Probiotic supplementation was moderately efficacious in decreasing ITT compared to control, with an SMD of 0.38 (95%CI: 0.23-0.53, P < 0.001). Subgroup analyses demonstrated statistically greater reductions in ITT with probiotics in subjects with vs without constipation (SMD: 0.57 vs 0.22, P < 0.01) and in studies with high vs low study quality (SMD: 0.45 vs 0.00, P = 0.01). Constipation (R (2) = 38%, P < 0.01), higher study quality (R (2) = 31%, P = 0.01), older age (R (2) = 27%, P = 0.02), higher percentage of female subjects (R (2) = 26%, P = 0.02), and fewer probiotic strains (R (2) = 20%, P < 0.05) were predictive of decreased ITT with probiotics in meta-regression. Medium to large treatment effects were identified with B. lactis HN019 (SMD: 0.67, P < 0.001) and B. lactis DN-173 010 (SMD: 0.54, P < 0.01) while other probiotic strains yielded negligible reductions in ITT relative to control. Probiotic supplementation is moderately efficacious for reducing ITT in adults. Probiotics were most efficacious in constipated subjects, when evaluated in high-quality studies, and with certain probiotic strains.

  16. The Transition to Parenthood and the Social Reality of Time.

    ERIC Educational Resources Information Center

    LaRossa, Ralph

    1983-01-01

    Compares physical time and social time, illustrated with a case study of a husband and wife who are in the midst of their transition to second-time (and unexpected) parenthood. Demonstrates the heuristic value of a social-time framework for understanding the transition to parenthood in particular and family systems in general. (Author/JAC)

  17. TRANSIT TIMING OBSERVATIONS FROM KEPLER. VIII. CATALOG OF TRANSIT TIMING MEASUREMENTS OF THE FIRST TWELVE QUARTERS

    SciTech Connect

    Mazeh, Tsevi; Nachmani, Gil; Holczer, Tomer; Sokol, Gil; Fabrycky, Daniel C.; Ford, Eric B.; Ragozzine, Darin; Sanchis-Ojeda, Roberto; Rowe, Jason F.; Lissauer, Jack J.; Zucker, Shay; Agol, Eric; Carter, Joshua A.; Quintana, Elisa V.; Steffen, Jason H.; Welsh, William

    2013-10-01

    Following the works of Ford et al. and Steffen et al. we derived the transit timing of 1960 Kepler objects of interest (KOIs) using the pre-search data conditioning light curves of the first twelve quarters of the Kepler data. For 721 KOIs with large enough signal-to-noise ratios, we obtained also the duration and depth of each transit. The results are presented as a catalog for the community to use. We derived a few statistics of our results that could be used to indicate significant variations. Including systems found by previous works, we have found 130 KOIs that showed highly significant times of transit variations (TTVs) and 13 that had short-period TTV modulations with small amplitudes. We consider two effects that could cause apparent periodic TTV—the finite sampling of the observations and the interference with the stellar activity, stellar spots in particular. We briefly discuss some statistical aspects of our detected TTVs. We show that the TTV period is correlated with the orbital period of the planet and with the TTV amplitude.

  18. Transit Timing Observations from Kepler. VIII. Catalog of Transit Timing Measurements of the First Twelve Quarters

    NASA Astrophysics Data System (ADS)

    Mazeh, Tsevi; Nachmani, Gil; Holczer, Tomer; Fabrycky, Daniel C.; Ford, Eric B.; Sanchis-Ojeda, Roberto; Sokol, Gil; Rowe, Jason F.; Zucker, Shay; Agol, Eric; Carter, Joshua A.; Lissauer, Jack J.; Quintana, Elisa V.; Ragozzine, Darin; Steffen, Jason H.; Welsh, William

    2013-10-01

    Following the works of Ford et al. and Steffen et al. we derived the transit timing of 1960 Kepler objects of interest (KOIs) using the pre-search data conditioning light curves of the first twelve quarters of the Kepler data. For 721 KOIs with large enough signal-to-noise ratios, we obtained also the duration and depth of each transit. The results are presented as a catalog for the community to use. We derived a few statistics of our results that could be used to indicate significant variations. Including systems found by previous works, we have found 130 KOIs that showed highly significant times of transit variations (TTVs) and 13 that had short-period TTV modulations with small amplitudes. We consider two effects that could cause apparent periodic TTV—the finite sampling of the observations and the interference with the stellar activity, stellar spots in particular. We briefly discuss some statistical aspects of our detected TTVs. We show that the TTV period is correlated with the orbital period of the planet and with the TTV amplitude.

  19. Evolution of a detailed physiological model to simulate the gastrointestinal transit and absorption process in humans, part II: extension to describe performance of solid dosage forms.

    PubMed

    Thelen, Kirstin; Coboeken, Katrin; Willmann, Stefan; Dressman, Jennifer B; Lippert, Jörg

    2012-03-01

    The physiological absorption model presented in part I of this work is now extended to account for dosage-form-dependent gastrointestinal (GI) transit as well as disintegration and dissolution processes of various immediate-release and modified-release dosage forms. Empirical functions of the Weibull type were fitted to experimental in vitro dissolution profiles of solid dosage forms for eight test compounds (aciclovir, caffeine, cimetidine, diclofenac, furosemide, paracetamol, phenobarbital, and theophylline). The Weibull functions were then implemented into the model to predict mean plasma concentration-time profiles of the various dosage forms. On the basis of these dissolution functions, pharmacokinetics (PK) of six model drugs was predicted well. In the case of diclofenac, deviations between predicted and observed plasma concentrations were attributable to the large variability in gastric emptying time of the enteric-coated tablets. Likewise, oral PK of furosemide was found to be predominantly governed by the gastric emptying patterns. It is concluded that the revised model for GI transit and absorption was successfully integrated with dissolution functions of the Weibull type, enabling prediction of in vivo PK profiles from in vitro dissolution data. It facilitates a comparative analysis of the parameters contributing to oral drug absorption and is thus a powerful tool for formulation design. Copyright © 2011 Wiley Periodicals, Inc.

  20. It's Time to Transition to Production, Now What?

    NASA Technical Reports Server (NTRS)

    Jansma, P. A.; Montgomery, Marc; Werntz, David; Payne, Michael

    1999-01-01

    When it's time to transition to production, it's easy to be too focused on the application itself and to overlook some areas crucial to your success. Learn about the 10 transition tasks that will ensure a smooth transition, and will prepare your organization to operate and use your system effectively.

  1. Transit timing analysis in the HAT-P-32 system

    NASA Astrophysics Data System (ADS)

    Seeliger, M.; Dimitrov, D.; Kjurkchieva, D.; Mallonn, M.; Fernandez, M.; Kitze, M.; Casanova, V.; Maciejewski, G.; Ohlert, J. M.; Schmidt, J. G.; Pannicke, A.; Puchalski, D.; Göğüş, E.; Güver, T.; Bilir, S.; Ak, T.; Hohle, M. M.; Schmidt, T. O. B.; Errmann, R.; Jensen, E.; Cohen, D.; Marschall, L.; Saral, G.; Bernt, I.; Derman, E.; Gałan, C.; Neuhäuser, R.

    2014-06-01

    We present the results of 45 transit observations obtained for the transiting exoplanet HAT-P-32b. The transits have been observed using several telescopes mainly throughout the YETI (Young Exoplanet Transit Initiative) network. In 25 cases, complete transit light curves with a timing precision better than 1.4 min have been obtained. These light curves have been used to refine the system properties, namely inclination i, planet-to-star radius ratio Rp/Rs, and the ratio between the semimajor axis and the stellar radius a/Rs. First analyses by Hartman et al. suggests the existence of a second planet in the system, thus we tried to find an additional body using the transit timing variation (TTV) technique. Taking also the literature data points into account, we can explain all mid-transit times by refining the linear ephemeris by 21 ms. Thus, we can exclude TTV amplitudes of more than ˜1.5 min.

  2. Gastrointestinal tattoos.

    PubMed

    Snider, T E; Goodell, W M; Pulitzer, D R

    1994-06-01

    Tattooing of the gastrointestinal tract is used to facilitate the relocation of biopsy sites or other sites of interest at the time of subsequent biopsy or surgery. Submucosal injection of sterile india ink produces a zone of blue-black coloration that is grossly visible from both the mucosal and serosal surfaces. The pathology of gastrointestinal tattoos has only been briefly mentioned previously in the medical literature. We report two cases of gastrointestinal tattooing: one that was done to mark the margin of resection in a patient with gastric lymphoma, and the second that occurred unintentionally following the administration of activated charcoal for drug overdosage in a patient with undiagnosed active inflammatory bowel disease. Unintentional tattooing of the gastrointestinal tract has, therefore, not been reported.

  3. Gamma-scintigraphic study of the gastrointestinal transit and in vivo dissolution of a controlled release diclofenac sodium formulation in xanthan gum matrices.

    PubMed

    Billa, N; Yuen, K H; Khader, M A; Omar, A

    2000-05-15

    A xanthan gum matrix controlled release tablet formulation containing diclofenac sodium was evaluated in vitro and was found to release the drug at a uniform rate. The gastrointestinal transit behaviour of the formulation as determined by gamma scintigraphy, using healthy male volunteers under fasted and fed conditions, indicated that gastric emptying was delayed with food intake. In contrast, the small intestinal transit remained practically unchanged under both food statuses. Therefore, the delay in caecal arrival observed in the fed state can be attributed to the delay in gastric emptying. Rate of diclofenac sodium absorption was generally higher in the fed state compared to the fasted state, however the total amount absorbed under both food statuses remained practically the same. The rate of in vivo dissolution of the drug in the fed state was faster compared to that in the fasted state. Thus, at the time of caecal arrival, in vivo dissolution was complete in the fed state, unlike in the fasted state, where almost 60% of the drug was delivered to the colon.

  4. Mean first-passage time of quantum transition processes

    NASA Astrophysics Data System (ADS)

    Qiu, Rong-Tao; Dai, Wu-Sheng; Xie, Mi

    2012-10-01

    In this paper, we consider the problem of mean first-passage time (MFPT) in quantum mechanics; the MFPT is the average time of the transition from a given initial state, passing through some intermediate states, to a given final state for the first time. We apply the method developed in statistical mechanics for calculating the MFPT of random walks to calculate the MFPT of a transition process. As applications, we (1) calculate the MFPT for multiple-state systems, (2) discuss transition processes occurring in an environmental background, (3) consider a roundabout transition in a hydrogen atom, and (4) apply the approach to laser theory.

  5. Transit light curves with finite integration time: Fisher information analysis

    SciTech Connect

    Price, Ellen M.; Rogers, Leslie A.

    2014-10-10

    Kepler has revolutionized the study of transiting planets with its unprecedented photometric precision on more than 150,000 target stars. Most of the transiting planet candidates detected by Kepler have been observed as long-cadence targets with 30 minute integration times, and the upcoming Transiting Exoplanet Survey Satellite will record full frame images with a similar integration time. Integrations of 30 minutes affect the transit shape, particularly for small planets and in cases of low signal to noise. Using the Fisher information matrix technique, we derive analytic approximations for the variances and covariances on the transit parameters obtained from fitting light curve photometry collected with a finite integration time. We find that binning the light curve can significantly increase the uncertainties and covariances on the inferred parameters when comparing scenarios with constant total signal to noise (constant total integration time in the absence of read noise). Uncertainties on the transit ingress/egress time increase by a factor of 34 for Earth-size planets and 3.4 for Jupiter-size planets around Sun-like stars for integration times of 30 minutes compared to instantaneously sampled light curves. Similarly, uncertainties on the mid-transit time for Earth and Jupiter-size planets increase by factors of 3.9 and 1.4. Uncertainties on the transit depth are largely unaffected by finite integration times. While correlations among the transit depth, ingress duration, and transit duration all increase in magnitude with longer integration times, the mid-transit time remains uncorrelated with the other parameters. We provide code in Python and Mathematica for predicting the variances and covariances at www.its.caltech.edu/∼eprice.

  6. Transit Light Curves with Finite Integration Time: Fisher Information Analysis

    NASA Astrophysics Data System (ADS)

    Price, Ellen M.; Rogers, Leslie A.

    2014-10-01

    Kepler has revolutionized the study of transiting planets with its unprecedented photometric precision on more than 150,000 target stars. Most of the transiting planet candidates detected by Kepler have been observed as long-cadence targets with 30 minute integration times, and the upcoming Transiting Exoplanet Survey Satellite will record full frame images with a similar integration time. Integrations of 30 minutes affect the transit shape, particularly for small planets and in cases of low signal to noise. Using the Fisher information matrix technique, we derive analytic approximations for the variances and covariances on the transit parameters obtained from fitting light curve photometry collected with a finite integration time. We find that binning the light curve can significantly increase the uncertainties and covariances on the inferred parameters when comparing scenarios with constant total signal to noise (constant total integration time in the absence of read noise). Uncertainties on the transit ingress/egress time increase by a factor of 34 for Earth-size planets and 3.4 for Jupiter-size planets around Sun-like stars for integration times of 30 minutes compared to instantaneously sampled light curves. Similarly, uncertainties on the mid-transit time for Earth and Jupiter-size planets increase by factors of 3.9 and 1.4. Uncertainties on the transit depth are largely unaffected by finite integration times. While correlations among the transit depth, ingress duration, and transit duration all increase in magnitude with longer integration times, the mid-transit time remains uncorrelated with the other parameters. We provide code in Python and Mathematica for predicting the variances and covariances at www.its.caltech.edu/~eprice.

  7. Sluggish gallbladder emptying and gastrointestinal transit after intake of common alcoholic beverages.

    PubMed

    Kasicka-Jonderko, A; Jonderko, K; Gajek, E; Piekielniak, A; Zawislan, R

    2014-02-01

    To study the movement along the gut and the effect upon the gallbladder volume of alcoholic beverages taken in the interdigestive state. The study comprised three research blocks attended by 12 healthy subjects each. Within a given research block volunteers underwent three examination sessions held on separate days, being offered an alcoholic beverage, or an aqueous ethanol solution of an identical proof, or a corresponding volume of isotonic glucose solution; the order of administration of the drinks was randomized. The beverages tested were: beer (4.7% vol, 400 ml), red wine (13.7% vol, 200 ml), whisky (43.5% vol, 100 ml) within the "Beer", "Wine", and "Whisky" research block, respectively. Gastric myoelectrical activity was examined electrogastrographically, gastric emptying with ¹³C-sodium acetate breath test, orocaecal transit with lactulose H₂ breath test, gallbladder emptying with ultrasonography, breath ethanol with alcotest. The study showed that alcoholic beverages were emptied from the stomach significantly slower than isotonic glucose. Alcoholic beverages produced by fermentation only (beer, red wine) were emptied from the stomach more slowly than ethanol solutions of identical proof, while gastric evacuation of whisky (distillation product) and matching alcohol solution was similar. The slower gastric evacuation of alcoholic beverages and ethanol solutions could not be ascribed to a disorganization of the gastric myoelectrical activity. The orocaecal transit of beer and red wine did not differ from that of isotonic glucose, whereas the orocaecal transit of whisky and high proof ethanol was markedly prolonged. Red wine and whisky, and to a similar extent control ethanol solutions caused an inhibition and delay of gallbladder emptying. We concluded that alcoholic beverages taken on an empty stomach exert a suppressive effect upon the transport function of the digestive tract and gallbladder emptying. The extent of this action depends on the type of a

  8. Effect of yacon (Smallanthus sonchifolius) on colonic transit time in healthy volunteers.

    PubMed

    Geyer, M; Manrique, I; Degen, L; Beglinger, C

    2008-01-01

    Yacon is a root crop which contains high amounts of fructooligosaccharides (FOS). The aim of this study was to investigate the effects of yacon syrup on colon transit time in healthy volunteers. In a placebo-controlled, double-blind study yacon was administered to 16 healthy individuals (8 males, 8 females) in a dose of 20 g daily (equal to 6.4 g FOS) in a 2-week crossover design. Each period was interrupted by a 2-week wash-out phase. Transit time was assessed by a radio-opaque marker technique. Transit time (mean +/- SEM) through the gastrointestinal tract was significantly decreased from 59.7 +/- 4.3 to 38.4 +/- 4.2 h (p < 0.001). Yacon was well tolerated with an excellent side effect profile. Bloating is not an uncommon side effect observed with FOS, but bloating-related disturbances were not significantly more often reported with yacon compared to placebo. Stool frequency increased from 1.1 +/- 0.1 to 1.3 +/- 0.2 times per day and the consistency showed a tendency for softer stools as assessed by a numerical depicted stool protocol. Neither parameter did, however, reach statistical significance. Yacon markedly accelerates colonic transit in healthy individuals. Further studies are needed in constipated patients to confirm these preliminary data. Due to the low caloric content of yacon, the root could be a useful treatment in constipated diabetics or obese patients. 2008 S. Karger AG, Basel.

  9. Analysis of small intestinal transit and colon arrival times of non-disintegrating tablets administered in the fasted state.

    PubMed

    Pišlar, Mitja; Brelih, Hana; Mrhar, Aleš; Bogataj, Marija

    2015-07-30

    In this study individual data on tablet gastrointestinal transit times (i.e. gastric emptying, small intestinal transit, ileocecal junction residence, and colon arrival times) were obtained from literature in order to present and analyze their distributions and relationships. The influence of the time of food intake after tablet administration in fasted state on gastrointestinal transit times was additionally evaluated. There were 114 measurements from subjects who received the first meal at 4h after tablet administration. Approximately 32% of the tablets arrived into the colon before the meal intake at 4h. An evident increase in the frequency of colon arrival of tablets within 40min after the meal intake at 4h post-dose was observed, where approximately 39% of all tablets arrived into the colon. This is in accordance with findings described in literature where a meal ingested several hours post-dose accelerates tablet transit through the terminal ileum and shortens the transit through the small intestine. The median (min, max) of gastric emptying, small intestinal transit, and colon arrival times in the group where the first meal intake was at 4h post-dose is 35 (0,192), 215 (60,544), and 254 (117,604) minutes, respectively. The dependence of colon arrival times on gastric emptying times was described by the nonparametric regression curve, and compared with the presumed interval of colon arrival times, calculated by summation of observed gastric emptying times and frequently cited small intestinal transit time interval, i.e. 3-4h. For shorter gastric emptying times the trend of colon arrival times was within the presumed interval. At short gastric emptying times many observation points are also within the presumed interval since this interval coincides with short period after meal intake at 4h post-dose. Additionally, in numerous occasions relatively long ileocecal junction residence times were obtained, which may be important information from the point of view of

  10. Magnetic marker monitoring: high resolution real-time tracking of oral solid dosage forms in the gastrointestinal tract.

    PubMed

    Weitschies, Werner; Blume, Henning; Mönnikes, Hubert

    2010-01-01

    Knowledge about the performance of dosage forms in the gastrointestinal tract is essential for the development of new oral delivery systems, as well as for the choice of the optimal formulation technology. Magnetic Marker Monitoring (MMM) is an imaging technology for the investigation of the behaviour of solid oral dosage forms within the gastrointestinal tract, which is based on the labelling of solid dosage forms as a magnetic dipole and determination of the location, orientation and strength of the dipole after oral administration using measurement equipment and localization methods that are established in biomagnetism. MMM enables the investigation of the performance of solid dosage forms in the gastrointestinal tract with a temporal resolution in the range of a few milliseconds and a spatial resolution in 3D in the range of some millimetres. Thereby, MMM provides real-time tracking of dosage forms in the gastrointestinal tract. MMM is also suitable for the determination of dosage form disintegration and for quantitative measurement of in vivo drug release in case of appropriate extended release dosage forms like hydrogel-forming matrix tablets. The combination of MMM with pharmacokinetic measurements (pharmacomagnetography) enables the determination of in vitro-in vivo correlations (IVIC) and the delineation of absorption sites in the gastrointestinal tract. Copyright 2009 Elsevier B.V. All rights reserved.

  11. WASP-14 b: transit timing analysis of 19 light curves

    NASA Astrophysics Data System (ADS)

    Raetz, St.; Maciejewski, G.; Seeliger, M.; Marka, C.; Fernández, M.; Güver, T.; Göğüş, E.; Nowak, G.; Vaňko, M.; Berndt, A.; Eisenbeiss, T.; Mugrauer, M.; Trepl, L.; Gelszinnis, J.

    2015-08-01

    Although WASP-14 b is one of the most massive and densest exoplanets on a tight and eccentric orbit, it has never been a target of photometric follow-up monitoring or dedicated observing campaigns. We report on new photometric transit observations of WASP-14 b obtained within the framework of Transit Timing Variations @ Young Exoplanet Transit Initiative (TTV@YETI). We collected 19 light curves of 13 individual transit events using six telescopes located in five observatories distributed in Europe and Asia. From light-curve modelling, we determined the planetary, stellar, and geometrical properties of the system and found them in agreement with the values from the discovery paper. A test of the robustness of the transit times revealed that in case of a non-reproducible transit shape the uncertainties may be underestimated even with a wavelet-based error estimation methods. For the timing analysis, we included two publicly available transit times from 2007 and 2009. The long observation period of seven years (2007-2013) allowed us to refine the transit ephemeris. We derived an orbital period 1.2 s longer and 10 times more precise than the one given in the discovery paper. We found no significant periodic signal in the timing-residuals and, hence, no evidence for TTV in the system.

  12. Effects of dates pulp extract and palm sap (Phoenix dactylifera L.) on gastrointestinal transit activity in healthy rats.

    PubMed

    Souli, Abdellaziz; Sebai, Hichem; Rtibi, Kaïs; Chehimi, Latifa; Sakly, Mohsen; Amri, Mohamed; El-Benna, Jamel

    2014-07-01

    The current study was performed to measure the chemical composition and the effects of dates pulp extract and palm sap on gastrointestinal transit (GIT) activity in healthy adult rats. In this respect, male Wistar rats fasted for 24 hours were used and received per orally (p.o.) sodium chloride (NaCl) (0,9%) (control group) or various doses of dates pulp extract (150 and 300 mg/kg, body weight [b.w.]) and palm sap (0.4 and 4 mL/kg, b.w.). Two other groups of rats (batch tests) received, respectively, clonidine (an alpha-2 adrenergic agonist, 1 mg/kg, b.w.) and yohimbine (an alpha-2 adrenergic antagonist, 2mg/kg, b.w.). Chemical analysis showed that the dates pulp extract is more rich in sugars and minerals, especially potassium and sucrose, as compared with palm sap composition. On the other hand, in vivo study showed that the aqueous dates pulp extract significantly, and dose dependently, increased the GIT activity while the palm sap slightly increased it. Moreover, a converse effect has been observed using clonidine (decreased 68%) and yohimbine (increased 33%) on the GIT activity. These findings suggest that dates pulp extract and palm sap have a stimulating effect on GIT activity in rats and confirm their use in traditional Tunisian medicine for the treatment of constipation.

  13. The involvement of 5-HT3 and 5-HT4 receptors in two models of gastrointestinal transit in mice.

    PubMed

    Pascual, D; Alsasua, A; Goicoechea, C; Martín, M I

    2002-07-05

    Our aim was to study the involvement of 5-hydroxytryptamine (5-HT)(3) and 5-HT(4) receptors in two models of gastrointestinal transit (GIT) in mice: the 5-hydroxytryptophan (5-HTP)-induced diarrhea and intestinal inflammation produced by an irritant agent, croton oil (CO). 5-HTP (10 mg/kg) produced diarrhea that was significantly inhibited after pretreatment with ondansetron (5-HT(3) antagonist) or RS 39604 (5-HT(4) antagonist) (1-5 mg/kg). The GIT speed was increased after CO and 5-HTP administration. 5-HT(3-4) antagonists decreased GIT after 5-HTP-treatment but not after CO-treatment. Our results show that 5-HT(3) and 5-HT(4) receptors are involved in 5-HTP-induced diarrhea. This may be the reason why 5-HT(3-4) antagonists could be useful in the treatment of carcinoid syndrome diarrhea. 5-HT(3-4) antagonists were not effective in the modifications of GIT; nevertheless, they could be useful in the treatment of inflammatory bowel diseases because some symptoms as abdominal pain, discomfort or abnormal bowel function are modulated via 5-HT(3).

  14. Effects of Dates Pulp Extract and Palm Sap (Phoenix dactylifera L.) on Gastrointestinal Transit Activity in Healthy Rats

    PubMed Central

    Souli, Abdellaziz; Rtibi, Kaïs; Chehimi, Latifa; Sakly, Mohsen; Amri, Mohamed; El-Benna, Jamel

    2014-01-01

    Abstract The current study was performed to measure the chemical composition and the effects of dates pulp extract and palm sap on gastrointestinal transit (GIT) activity in healthy adult rats. In this respect, male Wistar rats fasted for 24 hours were used and received per orally (p.o.) sodium chloride (NaCl) (0,9%) (control group) or various doses of dates pulp extract (150 and 300 mg/kg, body weight [b.w.]) and palm sap (0.4 and 4 mL/kg, b.w.). Two other groups of rats (batch tests) received, respectively, clonidine (an alpha-2 adrenergic agonist, 1 mg/kg, b.w.) and yohimbine (an alpha-2 adrenergic antagonist, 2mg/kg, b.w.). Chemical analysis showed that the dates pulp extract is more rich in sugars and minerals, especially potassium and sucrose, as compared with palm sap composition. On the other hand, in vivo study showed that the aqueous dates pulp extract significantly, and dose dependently, increased the GIT activity while the palm sap slightly increased it. Moreover, a converse effect has been observed using clonidine (decreased 68%) and yohimbine (increased 33%) on the GIT activity. These findings suggest that dates pulp extract and palm sap have a stimulating effect on GIT activity in rats and confirm their use in traditional Tunisian medicine for the treatment of constipation. PMID:24611963

  15. Transition Icons for Time Series Visualization and Exploratory Analysis.

    PubMed

    Nickerson, Paul; Baharloo, Raheleh; Wanigatunga, Amal A; Manini, Todd D; Tighe, Patrick J; Rashidi, Parisa

    2017-05-16

    The modern healthcare landscape has seen the rapid emergence of techniques and devices which temporally monitor and record physiological signals. The prevalence of time series data within the healthcare field necessitates the development of methods which can analyze the data in order to draw meaningful conclusions. Time series behavior is notoriously difficult to intuitively understand due to its intrinsic high-dimensionality, which is compounded in the case of analyzing groups of time series collected from different patients. Our framework, which we call Transition Icons, renders common patterns in a visual format useful for understanding the shared behavior within groups of time series. Transition Icons are adept at detecting and displaying subtle differences and similarities e.g. between measurements taken from patients receiving different treatment strategies or stratified by demographics. We introduce various methods which collectively allow for exploratory analysis of groups of time series, while being free of distribution assumptions and including simple heuristics for parameter determination. Our technique extracts discrete transition patterns from Symbolic Aggregate approXimation (SAX) representations, and compiles transition frequencies into a Bag of Patterns (BoP) constructed for each group. These transition frequencies are normalized and aligned in icon form to intuitively display the underlying patterns. We demonstrate the Transition Icon technique for two time series data sets - postoperative pain scores, and hip-worn accelerometer activity counts. We believe Transition Icons can be an important tool for researchers approaching time series data, as they give rich and intuitive information about collective time series behaviors.

  16. Endoscopic management of acute gastrointestinal bleeding in children: Time for a radical rethink.

    PubMed

    Thomson, Mike; Belsha, Dalia

    2016-02-01

    Currently we are no nearer than 10 or 20years ago providing a safe, adequate, and effective round-the-clock endoscopic services for acute life-threatening gastrointestinal bleeding in children. Preventable deaths are occurring still, and it is a tragedy. This is owing to a number of factors which require urgent attention. Skill-mix and the ability of available endoscopists in the UK are woeful. Manpower is spread too thinly and not concentrated in centers of excellence, which is necessary given the relative rarity of the presentation. Adult gastroenterologists are increasingly reticent regarding their help in increasingly litigious times. Recent work on identification of those children likely to require urgent endoscopic intervention has mirrored scoring systems that have been present in adult circles for many years and may allow appropriate and timely intervention. Recent technical developments such as that of Hemospray® may lower the threshold of competency in dealing with this problem endoscopically, thus allowing lives to be saved. Educational courses, mannequin and animal model training are important but so will be appropriate credentialing of individuals for this skill-set. Assessment of competency will become the norm and guidelines on a national level in each country mandatory if we are to move this problem from the "too difficult" to the "achieved". It is an urgent problem and is one of the last emergencies in pediatrics that is conducted poorly. This cannot and should not be allowed to continue unchallenged.

  17. Effects of enteric-coated methylnaltrexone in preventing opioid-induced delay in oral-cecal transit time.

    PubMed

    Yuan, C S; Foss, J F; O'Connor, M; Karrison, T; Osinski, J; Roizen, M F; Moss, J

    2000-04-01

    Methylnaltrexone is the first peripheral opioid receptor antagonist. It has the potential to prevent or reverse the peripherally mediated gastrointestinal effects of opioids. In previous human volunteer trials, we demonstrated that oral uncoated methylnaltrexone prevented morphine-induced delay in gastrointestinal transit time. This trial consisted of two studies: a pilot study and a controlled study. The lactulose hydrogen breath test was used to measure the oral-cecal transit time. In the pilot study with three subjects, an oral dose of 6.4 mg/kg enteric-coated methylnaltrexone effectively reversed the effects of morphine, producing transit times shorter than baseline levels. Subsequently, in the controlled study with another nine subjects, the transit time increased after intravenous morphine administration in all nine subjects, and the lower dose (3.2 mg/kg) of enteric-coated methylnaltrexone completely prevented the morphine-induced change in oral-cecal transit time in all nine subjects. Morphine significantly increased oral-cecal transit time from baseline level of 96.7 +/- 54.1 minutes (mean +/- SD) to 155.0 +/- 53.6 minutes (P = .014). After enteric-coated methylnaltrexone and morphine, the transit time returned to the baseline level (93.3 +/- 56.0 minutes; P = .55 compared with placebo). Plasma concentrations after 6.4 mg/kg and 3.2 mg/kg enteric-coated methylnaltrexone were substantially lower compared with those after 6.4 mg/kg of the uncoated formulation. Our results suggest that there is a prevailing direct and local luminal effect of enteric-coated methylnaltrexone and that the enteric-coated formulation exerts its gut pharmacologic actions more efficiently than the uncoated formulation.

  18. Correcting transit time distributions in coarse MODFLOW-MODPATH models.

    PubMed

    Abrams, Daniel

    2013-01-01

    In low to medium resolution MODFLOW models, the area occupied by sink cells often far exceeds the surface area of the streams they represent. As a result, MODPATH will calculate inaccurate particle traces and transit times. A frequency distribution of transit times for a watershed will also be in error. Such a distribution is used to assess the long-term impact of nonpoint source pollution on surface waters and wells. Although the inaccuracies for individual particles can only be avoided by increased model grid resolution or other advanced modeling techniques, the frequency distribution can be improved by scaling the particle transit times by an adjustment factor during post-processing.

  19. Gastrointestinal transit and prolonged ambulatory colonic motility in health and faecal incontinence

    PubMed Central

    Herbst, F; Kamm, M; Morris, G; Britton, K; Woloszko, J; Nicholls, R

    1997-01-01

    Background—Colonic motor function has not been studied in the ambulatory setting over a prolonged period in the unprepared state. Furthermore, the disturbance of this function in patients with faecal incontinence is unknown. 
Aim—To study colonic function over two to three days in the ambulatory, unprepared state in health and in patients with idiopathic faecal incontinence. 
Methods—Six healthy women and six women with faecal incontinence and a structurally intact anal sphincter ingested a dual radioisotope meal, and had a six sensor, solid state manometric probe colonoscopically inserted into the left colon. Scanning was performed until radioisotope left the gut and pressure was recorded for a median of 44hours. 
Results—Three of six patients showed abnormal gastric emptying. Patients showed no disturbance of colonic radioisotope transit. Controls had a median of 12, whereas patients had a median of 16, high amplitude propagated waves per 24 hours. In three patients urge incontinence was associated with high amplitude (up to 500 cm water) propagated waves which often reached the rectum. These high pressure waves were identical to those occuring in healthy subjects, the only difference being the lack of adequate sphincter response. Passive incontinence was not associated with colonic motor activity. Defaecation in all subjects was associated with identical propagated waves, and distal movement of 13% (median) of right colonic content and excretion of 32% from the left colon and rectum. The urge to defaecate was associated with either propagated waves (45%) or non-propagated contractions (55%). Rectal motor complexes were recorded in both groups of subjects, but similar rhythmic activity was also recorded in the sigmoid and descending colon. 
Conclusions—Normal colonic function consists of frequent high pressure propagated waves. Rhythmic activity occurs both proximal to and in the rectum. Defaecation is characterised by high pressure propagated

  20. Transition path time distribution and the transition path free energy barrier.

    PubMed

    Pollak, Eli

    2016-10-19

    The recent experimental measurement of the transition path time distributions of proteins presents several challenges to theory. Firstly, why do the fits of the experimental data to a theoretical expression lead to barrier heights which are much lower than the free energies of activation of the observed transitions? Secondly, there is the theoretical question of determining the transition path time distribution, without invoking the Smoluchowski limit. In this paper, we derive an exact expression for a transition path time distribution which is valid for arbitrary memory friction using the normal mode transformation which underlies Kramers' rate theory. We then recall that for low barriers, there is a noticeable difference between the transition path time distribution obtained with absorbing boundary conditions and free boundary conditions. For the former, the transition times are shorter, since recrossings of the boundaries are disallowed. As a result, if one uses the distribution based on absorbing boundary conditions to fit the experimental data, one will find that the transition path barrier will be larger than the values found based on a theory with free boundary conditions. We then introduce the paradigm of a transition path barrier height, and show that one should always expect it to be much smaller than the activation energy.

  1. Measurement of transit disorders in different gastrointestinal segments of patients with diabetes mellitus in relation to duration and severity of the disease by use of the metal-detector test.

    PubMed

    Folwaczny, C; Hundegger, K; Volger, C; Sorodoc, J; Kühn, M; Tatsch, K; Landgraf, R; Karbach, U

    1995-09-01

    The existence of gastrointestinal transit disorders in other intestinal segments beside the stomach in Type-1 diabetes mellitus (DM) and occurrence in Type-2 DM and in uremia has yet been confirmed only in few studies. Eleven healthy volunteers, 34 patients with Type-1, 32 patients with Type-2 DM in different stages of their disease and 34 non-diabetic patients with endstage-renal disease were investigated by use of the metal detector test. Patients were divided in three subgroups, depending on the duration of their disease: < 1 year: "Short", 1 - 10 years: "Middle", > 10 years: "Long". For comparison with the metal detector test scintigraphic studies of esophageal and gastric transit were performed in 17 patients and small intestinal transit was studied by use of the H2-lactulose breath test in 20 patients with long-standing DM Type-1. In Type-1 DM there is an increase of gastric (135 +/- 18, p < 0.01; 218 +/- 26, p < 0.0001 vs. 73 +/- 7 min.) and large intestinal transit times (79 +/- 18, P < 0.02; 76 +/- 11, p < 0.04 vs. 40 +/- 5 h) in patients with middle or long standing DM. In Type-2 DM similar transit disturbances occur (gastric emptying, long group: 120 +/- 15 min., p < 0.02; colonic transit, long group: 80 +/- 13 h, p < 0.01). In uremia transit disturbances were only found in patients with chronic ambulatory peritoneal dialysis (colonic transit: 71 +/- 9 h, p < 0.05). In 65% gastric scintigraphy and in 55% of cases the H2-lactulose breath test showed a prolongation of gastric emptying or a prolonged mouth-to-cecum transit. Transit disorders can occur in every stage of DM with preferential involvement of the stomach and the colon. These findings are of clinical relevance, since transit disturbances can result in instable metabolic condition.

  2. TRANSIT TIMING OBSERVATIONS FROM KEPLER. V. TRANSIT TIMING VARIATION CANDIDATES IN THE FIRST SIXTEEN MONTHS FROM POLYNOMIAL MODELS

    SciTech Connect

    Ford, Eric B.; Ragozzine, Darin; Holman, Matthew J.; Rowe, Jason F.; Barclay, Thomas; Borucki, William J.; Bryson, Stephen T.; Caldwell, Douglas A.; Kinemuchi, Karen; Koch, David G.; Lissauer, Jack J.; Still, Martin; Tenenbaum, Peter; Steffen, Jason H.; Batalha, Natalie M.; Fabrycky, Daniel C.; and others

    2012-09-10

    Transit timing variations provide a powerful tool for confirming and characterizing transiting planets, as well as detecting non-transiting planets. We report the results of an updated transit timing variation (TTV) analysis for 1481 planet candidates based on transit times measured during the first sixteen months of Kepler observations. We present 39 strong TTV candidates based on long-term trends (2.8% of suitable data sets). We present another 136 weaker TTV candidates (9.8% of suitable data sets) based on the excess scatter of TTV measurements about a linear ephemeris. We anticipate that several of these planet candidates could be confirmed and perhaps characterized with more detailed TTV analyses using publicly available Kepler observations. For many others, Kepler has observed a long-term TTV trend, but an extended Kepler mission will be required to characterize the system via TTVs. We find that the occurrence rate of planet candidates that show TTVs is significantly increased ({approx}68%) for planet candidates transiting stars with multiple transiting planet candidates when compared to planet candidates transiting stars with a single transiting planet candidate.

  3. Time to symptom improvement using elimination diets in non-IgE-mediated gastrointestinal food allergies.

    PubMed

    Lozinsky, Adriana Chebar; Meyer, Rosan; De Koker, Claire; Dziubak, Robert; Godwin, Heather; Reeve, Kate; Dominguez Ortega, Gloria; Shah, Neil

    2015-08-01

    The prevalence of food allergy has increased in recent decades, and there is paucity of data on time to symptom improvement using elimination diets in non-Immunoglobulin E (IgE)-mediated food allergies. We therefore aimed to assess the time required to improvement of symptoms using a symptom questionnaire for children with non-IgE-mediated food allergies on an elimination diet. A prospective observational study was performed on patients with non-IgE-mediated gastrointestinal food allergies on an elimination diet, who completed a questionnaire that includes nine evidence-based food allergic symptoms before and after the exclusion diet. The questionnaire measured symptoms individually from 0 (no symptom) to 5 (most severe) and collectively from 0 to 45. Children were only enrolled in the study if collectively symptoms improved with the dietary elimination within 4 or 8 weeks. Data from 131 patients were analysed including 90 boys with a median age of 21 months [IQR: 7 to 66]. Based on the symptom questionnaire, 129 patients (98.4%) improved after 4-week elimination diet and only two patients improved after 8 weeks. A statistically significant difference before and after commencing the elimination diet was seen in all nine recorded symptoms (all p < 0.001), and in the median of overall score (p < 0.001). This is the first study attempting to establish time to improve after commencing the diet elimination. Almost all children in this study improved within 4 weeks of following the elimination diet, under dietary supervision. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. AMON: Transition to real-time operations

    NASA Astrophysics Data System (ADS)

    Cowen, D. F.; Keivani, A.; Tešić, G.

    2016-04-01

    The Astrophysical Multimessenger Observatory Network (AMON) will link the world's leading high-energy neutrino, cosmic-ray, gamma-ray and gravitational wave observatories by performing real-time coincidence searches for multimessenger sources from observatories' subthreshold data streams. The resulting coincidences will be distributed to interested parties in the form of electronic alerts for real-time follow-up observation. We will present the science case, design elements, current and projected partner observatories, status of the AMON project, and an initial AMON-enabled analysis. The prototype of the AMON server has been online since August 2014 and processing archival data. Currently, we are deploying new high-uptime servers and will be ready to start issuing alerts as early as winter 2015/16.

  5. Pulse wave transit time for monitoring respiration rate.

    PubMed

    Johansson, A; Ahlstrom, C; Lanne, T; Ask, P

    2006-06-01

    In this study, we investigate the beat-to-beat respiratory fluctuations in pulse wave transit time (PTT) and its subcomponents, the cardiac pre-ejection period (PEP) and the vessel transit time (VTT) in ten healthy subjects. The three transit times were found to fluctuate in pace with respiration. When applying a simple breath detecting algorithm, 88% of the breaths seen in a respiration air-flow reference could be detected correctly in PTT. Corresponding numbers for PEP and VTT were 76 and 81%, respectively. The performance during hypo- and hypertension was investigated by invoking blood pressure changes. In these situations, the error rates in breath detection were significantly higher. PTT can be derived from signals already present in most standard monitoring set-ups. The transit time technology thus has prospects to become an interesting alternative for respiration rate monitoring.

  6. Effects of altered epididymal sperm transit time on sperm quality.

    PubMed

    Fernandez, Carla Dal Bianco; Porto, Elaine Manoela; Arena, Arielle Cristina; Kempinas, Wilma De Grava

    2008-08-01

    The epididymal sperm transit time seems to have an important role in the process of sperm maturation, and it seems that alterations to the transit can harm the process. The aim of the present work was to evaluate the influence of altered sperm transit time through the epididymis on sperm parameters and fertility of rats, as well as the role of testosterone in the alterations. Sprague-Dawley adult male rats were randomly assigned to four different groups and were treated for 12 days: (i) 10 microg/rat/day DES, to accelerate the transit; (ii) 6.25 mg/kg/day guanethidine sulphate, to delay the transit; (iii) same treatment as group 1, plus androgen supplementation; (iv) control animals received the vehicles. Guanethidine treatment delayed the sperm transit time through the epididymal cauda, provoking increased sperm reserves in this region. Animals exposed to DES showed an acceleration of sperm transit time in the epididymis, and consequently decreased sperm density in both epididymal regions, the caput-corpus and cauda, and diminished sperm motility. In both cases sperm production was not altered. Testosterone supplementation was able to restore the transit time to values close to normality, as they were higher than in the control rats. The same occurred in relation to sperm motility. Rats exposed to DES presented lower fertility after in utero artificial insemination using sperm collected from the proximal cauda epididymis. Therefore, it was concluded that the acceleration of rat sperm transit time appeared to harm normal sperm maturation, thus decreasing sperm quality and fertility capacity, in an androgen-dependent way.

  7. Possible involvement of 5-HT and 5-HT2 receptors in acceleration of gastrointestinal transit by escin Ib in mice.

    PubMed

    Matsuda, H; Li, Y; Yoshikawa, M

    2000-01-01

    We have reported previously that escin Ib accelerated gastrointestinal transit (GIT) in mice, and that its effect may be mediated by the release of endogenous prostaglandins (PGs) and nitric oxide (NO). In this study, the possible involvement of 5-HT and 5-HT receptors in the GIT acceleration of escin Ib was investigated in mice. The acceleration of GIT by escin Ib (25 or 50 mg/kg, p.o.) was attenuated by pretreatment with ritanserin (0.5-5 mg/kg, s.c., a 5-HT(2A/2C/2B) receptor antagonist), but not with MDL 72222 (1 and 5 mg/kg, s.c.) and metoclopramide (10 mg/kg, s.c.) (5-HT3 receptor antagonists) or tropisetron (1 and 10 mg/kg, s.c., a 5-HT(3/4) receptor antagonist). Furthermore, pretreatment with ketanserin (0.05-5 mg/kg, s.c.), haloperidol (1-5 mg/kg, s.c.) and spiperone (0.5-5 mg/kg, s.c.) (5-HT2A receptor antagonists), as well as a bolus of dl-p-chlorophenylalanine methyl ester (PCPA, 1000 mg/kg, p.o., 1, 6 or 24 h before administration of the sample) (an inhibitor of 5-HT synthesizing enzyme tryptophan hydroxylase) and reserpine (5 mg/kg, p.o.) (a 5-HT depletor), but not 6-hydroxydopamine (80 mg/kg, i.p., a dopamine depletor) or repeated PCPA (300 mg/kg x2, p.o., 72 and 48 h before administration of the sample), also attenuated the effects of escin Ib. It is postulated that escin Ib accelerates GIT, at least in part, by stimulating the synthesis of 5-HT to act through 5-HT2, possibly 5-HT2A receptors, which in turn causes the release of NO and PGs.

  8. Effects of escins Ia, Ib, IIa, and IIb from horse chestnuts on gastrointestinal transit and ileus in mice.

    PubMed

    Matsuda, H; Li, Y; Yoshikawa, M

    1999-08-01

    The effects of saponin fraction and its principal constituents escins Ia (1), Ib (2), IIa (3), and IIb (4) from horse chestnuts on gastrointestinal transit (GIT) and ileus were investigated in mice. Ileus was induced by acetic acid peritoneal irritation or by laparotomy with manipulation. One hour after the oral administration, the saponin fraction (12.5-100 mg/kg) and 14 (12.5-50 mg/ kg, except for 3 at 12.5 mg/kg) dose-dependently accelerated GIT. The optimal effects of the saponin fraction (25 mg/kg) occurred 5-240 min (applied intervals between the fraction and the charcoal meal) after the oral administration. The fraction (12.5-100 mg/ kg) and 1-4 (12.5-50 mg/kg, except for 1 and 2 at 12.5 mg/kg) dose-dependently prevented the inhibition of GIT induced by the acetic acid peritoneal irritation. They (12.5-100mg/kg) also dose-dependently prevented the inhibition of GIT induced by the laparotomy with manipulation. Desacylescins I (5) and II (6) (50 mg/kg) showed no such effects. These results demonstrated that the saponin fraction and 1-4 accelerated GIT and prevented the experimental ileus, and indicate that the 21, 22-acyl groups are essential for the accelerative effects of 1-4. The accelerations of GIT by 1-4 were completely abolished by the pretreatment with streptozotocin (100 mg/kg, iv), but not by the pretreatment with capsaicin (75 mg/kg in total, sc) or atropine (10 mg/kg, sc). These results imply that the sympathetic nervous system may be, but neither capsaicin-sensitive sensory nerves nor the cholinergic mechanism, involved in the accelerations of GIT by escins 1-4.

  9. Developments in Planet Detection using Transit Timing Variations

    SciTech Connect

    Steffen, Jason H.; Agol, Eric; /Washington U., Seattle, Astron. Dept.

    2006-12-01

    In a transiting planetary system, the presence of a second planet will cause the time interval between transits to vary. These transit timing variations (TTV) are particularly large near mean-motion resonances and can be used to infer the orbital elements of planets with masses that are too small to detect by any other means. The author presents the results of a study of simulated data where they show the potential that this planet detection technique has to detect and characterize secondary planets in transiting systems. These results have important ramifications for planetary transit searches since each transiting system presents an opportunity for additional discoveries through a TTV analysis. They present such an analysis for 13 transits of the HD 209458 system that were observed with the Hubble Space Telescope. This analysis indicates that a putative companion in a low-order, mean-motion resonance can be no larger than the mass of the Earth and constitutes, to date, the most sensitive probe for extrasolar planets that orbit main sequence stars. The presence or absence of small planets in low-order, mean-motion resonances has implications for theories of the formation and evolution of planetary systems. Since TTV is most sensitive in these regimes, it should prove a valuable tool not only for the detection of additional planets in transiting systems, but also as a way to determine the dominant mechanisms of planet formation and the evolution of planetary systems.

  10. Confocal laser endomicroscopy and immunoendoscopy for real-time assessment of vascularization in gastrointestinal malignancies.

    PubMed

    Gheonea, Dan Ionuţ; Cârţână, Tatiana; Ciurea, Tudorel; Popescu, Carmen; Bădărău, Anca; Săftoiu, Adrian

    2011-01-07

    Gastrointestinal cancers represent a major cause of morbidity and mortality, with incomplete response to chemotherapy in the advanced stages and poor prognosis. Angiogenesis plays a crucial part in tumor growth and metastasis, with most gastrointestinal cancers depending strictly on the development of a new and devoted capillary network. Confocal laser endomicroscopy is a new technology which allows in vivo microscopic analysis of the gastrointestinal mucosa and its microvascularization during ongoing endoscopy by using topically or systemically administered contrast agents. Targeting markers of angiogenesis in association with confocal laser endomicroscopic examination (immunoendoscopy), as a future challenge, will add functional analysis to the morphological aspect of the neoplastic process. This review describes previous experience in endomicroscopic examination of the upper and lower digestive tract with emphasis on vascularization, resulting in a broad spectrum of potential clinical applications, and also preclinical research that could be translated to human studies.

  11. NASA's SDO Captures Mercury Transit Time-lapses SDO Captures Mercury Transit Time-lapse

    NASA Image and Video Library

    2017-09-28

    Less than once per decade, Mercury passes between the Earth and the sun in a rare astronomical event known as a planetary transit. The 2016 Mercury transit occurred on May 9th, between roughly 7:12 a.m. and 2:42 p.m. EDT. The images in this video are from NASA’s Solar Dynamics Observatory Music: Encompass by Mark Petrie For more info on the Mercury transit go to: www.nasa.gov/transit This video is public domain and may be downloaded at: svs.gsfc.nasa.gov/12235 NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  12. Daylight Saving Time Transitions and Road Traffic Accidents

    PubMed Central

    Lahti, Tuuli; Nysten, Esa; Haukka, Jari; Sulander, Pekka; Partonen, Timo

    2010-01-01

    Circadian rhythm disruptions may have harmful impacts on health. Circadian rhythm disruptions caused by jet lag compromise the quality and amount of sleep and may lead to a variety of symptoms such as fatigue, headache, and loss of attention and alertness. Even a minor change in time schedule may cause considerable stress for the body. Transitions into and out of daylight saving time alter the social and environmental timing twice a year. According to earlier studies, this change in time-schedule leads to sleep disruption and fragmentation of the circadian rhythm. Since sleep deprivation decreases motivation, attention, and alertness, transitions into and out of daylight saving time may increase the amount of accidents during the following days after the transition. We studied the amount of road traffic accidents one week before and one week after transitions into and out of daylight saving time during years from 1981 to 2006. Our results demonstrated that transitions into and out of daylight saving time did not increase the number of traffic road accidents. PMID:20652036

  13. Daylight saving time transitions and road traffic accidents.

    PubMed

    Lahti, Tuuli; Nysten, Esa; Haukka, Jari; Sulander, Pekka; Partonen, Timo

    2010-01-01

    Circadian rhythm disruptions may have harmful impacts on health. Circadian rhythm disruptions caused by jet lag compromise the quality and amount of sleep and may lead to a variety of symptoms such as fatigue, headache, and loss of attention and alertness. Even a minor change in time schedule may cause considerable stress for the body. Transitions into and out of daylight saving time alter the social and environmental timing twice a year. According to earlier studies, this change in time-schedule leads to sleep disruption and fragmentation of the circadian rhythm. Since sleep deprivation decreases motivation, attention, and alertness, transitions into and out of daylight saving time may increase the amount of accidents during the following days after the transition. We studied the amount of road traffic accidents one week before and one week after transitions into and out of daylight saving time during years from 1981 to 2006. Our results demonstrated that transitions into and out of daylight saving time did not increase the number of traffic road accidents.

  14. Domain wall formation in late-time phase transitions

    NASA Technical Reports Server (NTRS)

    Kolb, Edward W.; Wang, Yun

    1992-01-01

    We examine domain wall formulation in late time phase transitions. We find that in the invisible axion domain wall phenomenon, thermal effects alone are insufficient to drive different parts of the disconnected vacuum manifold. This suggests that domain walls do not form unless either there is some supplemental (but perhaps not unreasonable) dynamics to localize the scalar field responsible for the phase transition to the low temperature maximum (to an extraordinary precision) before the onset of the phase transition, or there is some non-thermal mechanism to produce large fluctuations in the scalar field. The fact that domain wall production is not a robust prediction of late time transitions may suggest future directions in model building.

  15. Origin of time before inflation from a topological phase transition

    NASA Astrophysics Data System (ADS)

    Bellini, Mauricio

    2017-09-01

    We study the origin of the universe (or pre-inflation) by suggesting that the primordial space-time in the universe suffered a global topological phase transition, from a 4D Euclidean manifold to an asymptotic 4D hyperbolic one. We introduce a complex time, τ, such that its real part becomes dominant after started the topological phase transition. Before the big bang, τ is a space-like coordinate, so that can be considered as a reversal variable. After the phase transition is converted in a causal variable. The formalism solves in a natural manner the quantum to classical transition of the geometrical relativistic quantum fluctuations: σ, which has a geometric origin.

  16. Oral transit time: a critical review of the literature

    PubMed Central

    SOARES, Thais Jacóe; MORAES, Danielle Pedroni; de MEDEIROS, Gisele Chagas; SASSI, Fernanda Chiarion; ZILBERSTEIN, Bruno; de ANDRADE, Claudia Regina Furquim

    2015-01-01

    Introduction Oral transit time is one of the parameters observed during the clinical assessment of the swallowing function. The importance of this parameter is due to its impact on the total duration of a meal, whose consequence can be an unfavorable nutritional prognostic. Objective To document scientific papers that measure oral transit time in healthy subjects. Method The review followed the steps proposed by the Cochrane Handbook. The search was done via the PubMed database through the use of descriptors related to the oral phase of swallowing, as well as to types of food consistency. Results The articles on the theme had different definitions for oral transit time, as well as heterogeneity of tested volumes, age and gender of the participants. The times found varied from 0.35 s to 1.54 s for liquids, from 0.39 s to 1.05 s for pasty foods and from 1 s to 12.8 s for solid foods. Also, regardless of volume or consistency, oral transit time in elderly people is significantly longer than in adults. Conclusion There's no consensus in the literature about oral transit time in healthy subjects. However, this parameter should be valued during the assessment of the swallowing function due to its negative impact on the dynamics of swallowing, which can cause high energy expenditure during feeding. PMID:26176255

  17. Nonadiabatic transitions in finite-time adiabatic rapid passage

    NASA Astrophysics Data System (ADS)

    Lu, T.; Miao, X.; Metcalf, H.

    2007-06-01

    To apply the adiabatic rapid passage process repetitively [T. Lu, X. Miao, and H. Metcalf, Phys. Rev. A 71, 061405(R) (2005)], the nonadiabatic transition probability of a two-level atom subject to chirped light pulses over a finite period of time needs to be calculated. Using a unitary first-order perturbation method in the rotating adiabatic frame, an approximate formula has been derived for such transition probabilities in the entire parameter space of the pulses.

  18. TTVFaster: First order eccentricity transit timing variations (TTVs)

    NASA Astrophysics Data System (ADS)

    Agol, Eric; Deck, Katherine

    2016-04-01

    TTVFaster implements analytic formulae for transit time variations (TTVs) that are accurate to first order in the planet-star mass ratios and in the orbital eccentricities; the implementations are available in several languages, including IDL, Julia, Python and C. These formulae compare well with more computationally expensive N-body integrations in the low-eccentricity, low mass-ratio regime when applied to simulated and to actual multi-transiting Kepler planet systems.

  19. Changes in ischemic stroke occurrence following daylight saving time transitions.

    PubMed

    Sipilä, Jussi O T; Ruuskanen, Jori O; Rautava, Päivi; Kytö, Ville

    Circadian rhythm disruption has been associated with increased risk of ischemic stroke (IS). Daylight saving time (DST) transitions disrupt circadian rhythms and shifts the pattern of diurnal variation in stroke onset, but effects on the incidence of IS are unknown. Effects of 2004-2013 DST transitions on IS hospitalizations and in-hospital mortality were studied nationwide in Finland. Hospitalizations during the week following DST transition (study group, n = 3033) were compared to expected hospitalizations (control group, n = 11,801), calculated as the mean occurrence during two weeks prior to and two weeks after the index week. Hospitalizations for IS increased during the first two days (Relative Risk 1.08; CI 1.01-1.15, P = 0.020) after transition, but difference was diluted when observing the whole week (RR 1.03; 0.99-1.06; P = 0.069). Weekday-specific increase was observed on the second day (Monday; RR 1.09; CI 1.00-1.90; P = 0.023) and fifth day (Thursday; RR 1.11; CI 1.01-1.21; P = 0.016) after transition. Women were more susceptible than men to temporal changes during the week after DST transitions. Advanced age (>65 years) (RR 1.20; CI 1.04-1.38; P = 0.020) was associated with increased risk during the first two days, and malignancy (RR 1.25; CI 1.00-1.56; P = 0.047) during the week after DST transition. DST transitions appear to be associated with an increase in IS hospitalizations during the first two days after transitions but not during the entire following week. Susceptibility to effects of DST transitions on occurrence of ischemic stroke may be modulated by gender, age and malignant comorbidities. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. A modified radiographic method for estimating segmental colonic transit time in subjects with rapid gut transit.

    PubMed

    Pai, C G; Kurian, G

    1999-07-01

    In this study on Indian subjects, the single X-ray method was assessed for its reliability in measuring the transit of particulate matter through the colon, and if inaccurate a suitable and simple alternative was to be devised. Radio-opaque markers were serially followed in 20 normal male volunteers. This was done by three 12 hourly radiographs and by stool collection to determine the transit time through the colon and its segments. It was compared with similar parameters calculated from the same data using one radiograph and three combinations of two radiographs each. The mean +/- SD colonic transit time determined by using three X-rays was 18.0 +/- 6.6 h which agreed well with the mean mouth-to-anus transit time of 24.2 +/- 6.8 h (mean +/- SDdiff = -6.2 +/- 2.9). When two of the three X-rays were used in various combinations, the best results were obtained with the method including radiographs at 12 and 36 h. Parameters calculated from a single radiograph done 36 h after the ingestion of makers showed lesser agreement with the results of the three radiograph method. Therefore in subjects with rapid gut transit, the simplified method for estimating the colonic and segmental transit times using a single X-ray is inaccurate. Using two radiographs enhances the accuracy.

  1. STELLAR PROPER MOTION AND THE TIMING OF PLANETARY TRANSITS

    SciTech Connect

    Rafikov, Roman R.

    2009-08-01

    Duration and period of transits in extrasolar planetary systems can exhibit long-term variations for a variety of reasons. Here we investigate how systemic proper motion, which steadily re-orients planetary orbit with respect to our line of sight, affects the timing of transits. We find that in a typical system with a period of several days, proper motion at the level of 100 mas yr{sup -1} makes transit duration vary at a rate {approx}10-100 ms yr{sup -1}. In some isolated systems this variation is at the measurable level (can be as high as 0.6 s yr{sup -1} for GJ436) and may exceed all other transit-timing contributions (due to the general relativity, stellar quadrupole, etc.). In addition, proper motion causes evolution of the observed period between transits P {sub obs} via the Shklovskii effect at a rate {approx}>10 {mu}s yr{sup -1} for the nearby transiting systems (0.26 ms yr{sup -1} in GJ436), which in some cases exceeds all other contributions to P-dot{sub obs}. Earth's motion around the Sun gives rise to additional periodic timing signal (even for systems with zero intrinsic proper motion) allowing a full determination of the spatial orientation of the planetary orbit. Unlike most other timing effects, the proper motion signatures persist even in systems with zero eccentricity and get stronger as the planetary period increases. They should be the dominant cause of transit-timing variations in isolated wide-separation (periods of months) systems that will be sought by Kepler.

  2. The effect of food on gastrointestinal (GI) transit of sustained-release ibuprofen tablets as evaluated by gamma scintigraphy

    SciTech Connect

    Borin, M.T.; Khare, S.; Beihn, R.M.; Jay, M. )

    1990-03-01

    The GI transit of radiolabeled sustained-release ibuprofen 800-mg tablets in eight healthy, fed volunteers was monitored using external gamma scintigraphy. Ibuprofen serum concentrations were determined from blood samples drawn over 36 hr following dosing. Sustained-release ibuprofen tablets containing 0.18% of 170Er2O3 (greater than 96% 170Er) in the bulk formulation were manufactured under pilot-scale conditions and were radiolabeled utilizing a neutron activation procedure which converted stable 170Er to radioactive 171Er (t1/2 = 7.5 hr). At the time of dosing, each tablet contained 50 mu Ci of 171Er. Dosage form position were reported at various time intervals. In five subjects the sustained-release tablet remained in the stomach and eroded slowly over 7-12 hr, resulting in gradual increases in small bowel radioactivity. In the remaining three subjects, the intact tablet was ejected from the stomach and a gastric residence time of approximately 4 hr was measured. This is in marked contrast to a previous study conducted in fasted volunteers in which gastric retention time ranged from 10 to 60 min. Differences in GI transit between fed and fasted volunteers had little effect on ibuprofen bioavailability. AUC and Tmax were unaltered and Cmax was increased by 24%, which is in agreement with results from a previous, crossover-design food effect study.

  3. Transit time and charge storage measurements in heavily doped emitters

    NASA Technical Reports Server (NTRS)

    Neugroschel, A.; Park, J. S.; Hwang, B. Y.

    1986-01-01

    A first direct measurement of the minority-carrier transit time in a transparent heavily doped emitter layer is reported. The value was obtained by a high-frequency conductance method recently developed and used for low-doped Si. The transit time coupled with the steady-state current enables the determination of the quasi-static charge stored in the emitter and the quasi-static emitter capacitance. Using a transport model, from the measured transit time, the value for the minority-carrier diffusion coefficient and mobility is estimated. The measurements were done using a heavily doped emitter of the Si p(+)-n-p bipolar transistor. The new result indicates that the position-averaged minority-carrier diffusion coefficients may be much smaller than the corresponding majority-carrier values for emitters having a concentration ranging from about 3 x 10 to the 19th per cu cm to 10 to the 20th per cu cm.

  4. Transit time and charge storage measurements in heavily doped emitters

    NASA Technical Reports Server (NTRS)

    Neugroschel, A.; Park, J. S.; Hwang, B. Y.

    1986-01-01

    A first direct measurement of the minority-carrier transit time in a transparent heavily doped emitter layer is reported. The value was obtained by a high-frequency conductance method recently developed and used for low-doped Si. The transit time coupled with the steady-state current enables the determination of the quasi-static charge stored in the emitter and the quasi-static emitter capacitance. Using a transport model, from the measured transit time, the value for the minority-carrier diffusion coefficient and mobility is estimated. The measurements were done using a heavily doped emitter of the Si p(+)-n-p bipolar transistor. The new result indicates that the position-averaged minority-carrier diffusion coefficients may be much smaller than the corresponding majority-carrier values for emitters having a concentration ranging from about 3 x 10 to the 19th per cu cm to 10 to the 20th per cu cm.

  5. Survival and Germination of Bacillus cereus Spores without Outgrowth or Enterotoxin Production during In Vitro Simulation of Gastrointestinal Transit

    PubMed Central

    Ceuppens, Siele; Uyttendaele, Mieke; Drieskens, Katrien; Heyndrickx, Marc; Rajkovic, Andreja; Boon, Nico

    2012-01-01

    To study the gastrointestinal survival and enterotoxin production of the food-borne pathogen Bacillus cereus, an in vitro simulation experiment was developed to mimic gastrointestinal passage in 5 phases: (i) the mouth, (ii) the stomach, with gradual pH decrease and fractional emptying, (iii) the duodenum, with high concentrations of bile and digestive enzymes, (iv) dialysis to ensure bile reabsorption, and (v) the ileum, with competing human intestinal bacteria. Four different B. cereus strains were cultivated and sporulated in mashed potato medium to obtain an inoculum of 7.0 log spores/ml. The spores showed survival and germination during the in vitro simulation of gastrointestinal passage, but vegetative outgrowth of the spores was suppressed by the intestinal bacteria during the final ileum phase. No bacterial proliferation or enterotoxin production was observed, despite the high inoculum levels. Little strain variability was observed: except for the psychrotrophic food isolate, the spores of all strains survived well throughout the gastrointestinal passage. The in vitro simulation experiments investigated the survival and enterotoxin production of B. cereus in the gastrointestinal lumen. The results obtained support the hypothesis that localized interaction of B. cereus with the host's epithelium is required for diarrheal food poisoning. PMID:22923409

  6. Comparative analysis of the gene expression profile of probiotic Lactobacillus casei Zhang with and without fermented milk as a vehicle during transit in a simulated gastrointestinal tract.

    PubMed

    Wang, Jicheng; Zhong, Zhi; Zhang, Wenyi; Bao, Qiuhua; Wei, Aibin; Meng, He; Zhang, Heping

    2012-06-01

    Studies have found that the survival of probiotics could be strongly enhanced with dairy products as delivery vehicles, but the molecular mechanism by which this might occur has seldom been mentioned. In this study, microarray technology was used to detect the gene expression profile of Lactobacillus casei Zhang with and without fermented milk used as a delivery vehicle during transit in simulated gastrointestinal juice. Numerous genes of L. casei Zhang in strain suspension were upregulated compared to those from L. casei Zhang in fermented milk. These data might indicate that L. casei Zhang is stimulated directly without the protection of fermented milk, and the high-level gene expression observed here may be a stress response at the transcriptional level. A large proportion of genes involved in translation and cell division were downregulated in the bacteria that were in strain suspension during transit in simulated intestinal juice. This may impede protein biosynthesis and cell division and partially explain the lower viability of L. casei Zhang during transit in the gastrointestinal tract without the delivery vehicle. Copyright © 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  7. Noise-induced transition in human reaction times

    NASA Astrophysics Data System (ADS)

    Medina, José M.; Díaz, José A.

    2016-09-01

    The human reaction/response time can be defined as the time elapsed from the onset of stimulus presentation until a response occurs in many sensory and cognitive processes. A reaction time model based on Piéron’s law is investigated. The model shows a noise-induced transition in the moments of reaction time distributions due to the presence of strong additive noise. The model also demonstrates that reaction times do not follow fluctuation scaling between the mean and the variance but follow a generalized version between the skewness and the kurtosis. The results indicate that noise-induced transitions in the moments govern fluctuations in sensory-motor transformations and open an insight into the macroscopic effects of noise in human perception and action. The conditions that lead to extreme reaction times are discussed based on the transfer of information in neurons.

  8. Challenges of Detecting Unseen Planetary Companions with Transit Timing Variations

    NASA Astrophysics Data System (ADS)

    Veras, Dimitri; Ford, E. B.; Payne, M. J.

    2010-05-01

    Both ground and space-based transit observatories are poised to significantly increase the number of known transiting planets and the number of precisely measured transit times. The variation in a planet's transit times may be used to infer the presence of additional planets. Deducing the masses and orbital parameters of such planets from transit time variations (TTVs) alone is a rich and increasingly relevant dynamical problem. In this work, we evaluate the extent of the degeneracies in this process, systematically explore the dependence of TTV signals on several parameters, and provide phase space plots that could aid observers in planning future observations. Our explorations are focused on a likely-to-be prevalent situation: a known transiting hot Jupiter and a suspected external terrestrial-like perturber following a nearly coplanar orbit. Through 10 million N-body simulations, we demonstrate how TTV signal amplitudes may vary by orders of magnitude due to slight variations in any one orbital parameter (0.001 AU in semimajor axis, 0.005 in eccentricity, or a few degrees in mean longitude), and quantify the number of consecutive transit observations necessary in order to obtain a reasonable opportunity to characterize the unseen planet (> 50 observations). Planets in or near period commensurabilities of the form p:q, where p < 20 and q < 4, produce distinct TTV signatures, regardless of whether the planets are actually locked in a mean motion resonance. We distinguish these systems from the secular systems in our explorations. Additionally, we find that computing the autocorrelation function of a TTV signal can significantly help break the degeneracy in particular parameter regimes, and postulate on how this method might aid TTV analyses in future studies focused on particular exosystems.

  9. Heart failure: evaluation of cardiopulmonary transit times with time-resolved MR angiography.

    PubMed

    Shors, Stephanie M; Cotts, William G; Pavlovic-Surjancev, Biljana; François, Christopher J; Gheorghiade, Mihai; Finn, J Paul

    2003-12-01

    To measure cardiopulmonary transit times in patients with heart failure by using low-dose, time-resolved magnetic resonance (MR) angiography and to determine if transit curves reflect conventional MR indexes of cardiac function. Twenty-six patients with heart failure and left ventricular (LV) systolic dysfunction (17 men and nine women; age range, 22-78 years) and thirteen control subjects (eight men and five women; age range, 23-59 years) were examined with MR imaging. The examination consisted of rapid cine MR imaging throughout the heart, followed by contrast material-enhanced time-resolved three-dimensional MR angiography of the cardiac chambers and pulmonary vasculature. Time-intensity curves for the pulmonary artery and ascending aorta were derived from the MR angiography images. Cardiopulmonary transit times and dispersions (full widths at half maximum [FWHM]) were determined from the curves. Transit times and FWHM values for the patients with heart failure were compared with control values by using two-tailed t tests, and transit time was correlated with standard LV functional parameters calculated from the cine MR images. Cardiopulmonary transit times and FWHM values were significantly prolonged in the patients with heart failure compared with those in the control patients (P <.001). Transit time correlated directly with LV end-diastolic and end-systolic volumes and inversely with LV ejection fraction (R > 0.60). However, transit time did not correlate strongly with age, body surface area, heart rate, LV mass, stroke volume, cardiac output, or sphericity index. Time-resolved MR angiography allows determination of cardiopulmonary transit times that are significantly prolonged in heart failure and correlate directly with LV volumes and inversely with LV ejection fraction.

  10. Symptomatic cytomegalovirus gastrointestinal infection with positive quantitative real-time PCR findings in apparently immunocompetent patients: a case series.

    PubMed

    Bernard, S; Germi, R; Lupo, J; Laverrière, M-H; Masse, V; Morand, P; Gavazzi, G

    2015-12-01

    Cytomegalovirus (CMV) gastrointestinal disease rarely occurs in immunocompetent patients, and is mainly diagnosed on the basis of histopathological findings. Real-time PCR for CMV DNA quantification is considered to be a useful diagnostic tool, but its place in the diagnostic strategy is not clearly defined. The goal of the study was to describe the clinical and paraclinical features of apparently immunocompetent patients with CMV gastrointestinal disease diagnosed according to quantitative PCR results. In this retrospective study conducted in a 1500-bed tertiary-care centre, we reviewed the case records of apparently immunocompetent patients with positive findings of CMV DNA in gastrointestinal biopsies with compatible symptoms and endoscopic findings. A total of 13 patients were included between January 2007 and December 2010. The median age was 81 years, and 54% of patients had underlying immune-modulating conditions. Diarrhoea, haematochezia and dysphagia were the main reported symptoms, and ulcers were the main endoscopic findings. The mean value of CMV DNA load in gastrointestinal biopsies was 3845 copies/μg total DNA (range, 15-15 500 copies/μg total DNA). The highest values were found in two patients who were diagnosed with adenocarcinoma in the subsequent course of CMV infection. Clinical features were similar to those in previous series in which diagnosis was based on histopathological analysis. Elderly people are more commonly affected, and a link with immune senescence is possible. Quantification of CMV DNA seems to be a useful tool for diagnosis when combined with clinical and endoscopic findings, but further studies are necessary to interpret quantitative values. Copyright © 2015 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  11. Effects of Posture and Meal Volume on Gastric Emptying, Intestinal Transit, Oral Glucose Tolerance, Blood Pressure and Gastrointestinal Symptoms After Roux-en-Y Gastric Bypass.

    PubMed

    Nguyen, Nam Q; Debreceni, Tamara L; Burgstad, Carly M; Wishart, Judith M; Bellon, Max; Rayner, Chris K; Wittert, Gary A; Horowitz, Michael

    2015-08-01

    The purpose of this study is to determine the effects of posture and drink volume on gastric/pouch emptying (G/PE), intestinal transit, hormones, absorption, glycaemia, blood pressure and gastrointestinal (GI) symptoms after gastric bypass (Roux-en-Y gastric bypass (RYGB)). Ten RYGB subjects were studied on four occasions in randomized order (sitting vs. supine posture; 50 vs. 150 ml of labelled water mixed with 3 g 3-O-methyl-D-glucose (3-OMG) and 50 g glucose). G/PE, caecal arrival time (CAT), blood glucose, plasma insulin, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), peptide YY (PYY), 3-OMG, blood pressure, heart rate and GI symptoms were assessed over 240 min. Controls were ten volunteers with no medical condition or previous abdominal surgery, who were studied with the 150-ml drink in the sitting position. Compared to controls, PE (P < 0.001) and CAT (P < 0.001) were substantially more rapid in RYGB subjects. In RYGB, PE was more rapid in the sitting position (2.5 ± 0.7 vs. 16.6 ± 5.3 min, P = 0.02) and tends to be faster after 150 ml than the 50-ml drinks (9.5 ± 2.9 vs. 14.0 ± 3.5 min, P = 0.16). The sitting position and larger volume drinks were associated with greater releases of insulin, GLP-1 and PYY, as well as more hypotension (P < 0.01), tachycardia (P < 0.01) and postprandial symptoms (P < 0.001). Pouch emptying, blood pressure and GI symptoms after RYGB are dependent on both posture and meal volume.

  12. Behavior of the Meat-Borne Bacterium Lactobacillus sakei during Its Transit through the Gastrointestinal Tracts of Axenic and Conventional Mice ▿ †

    PubMed Central

    Chiaramonte, Fabrizio; Blugeon, Sébastien; Chaillou, Stéphane; Langella, Philippe; Zagorec, Monique

    2009-01-01

    A Lactobacillus sakei strain named FLEC01 was isolated from human feces and characterized genotypically. Comparison of the genetic features of this strain with those of both the meat-borne L. sakei strain 23K and another human isolate, LTH5590, showed that they belong to different but closely related clusters. The three L. sakei strains did not persist and only transited through the gastrointestinal tracts (GITs) of conventional C3H/HeN mice. In contrast, they all colonized the GITs of axenic mice and rapidly reached a population of 109 CFU/g of feces, which remained stable until day 51. Five days after mice were fed, a first subpopulation, characterized by small colonies, appeared and reached 50% of the total L. sakei population in mice. Fifteen to 21 days after feeding, a second subpopulation, characterized by rough colonies, appeared. It coexisted with the two other populations until day 51, and its cell shapes were also affected, suggesting a dysfunction of the cell division or cell wall. No clear difference between the behaviors of the meat-borne strain and the two human isolates in both conventional and axenic mice was observed, suggesting that L. sakei is a food-borne bacterium rather than a commensal one and that its presence in human feces originates from diet. Previous observations of Escherichia coli strains suggest that the mouse GIT environment could induce mutations to increase their survival and colonization capacities. Here, we observed similar mutations concerning a food-grade gram-positive bacterium for the first time. PMID:19447958

  13. TRANSIT TIMING VARIATIONS FOR ECCENTRIC AND INCLINED EXOPLANETS

    SciTech Connect

    Nesvorny, David

    2009-08-20

    The Transit Timing Variation (TTV) method relies on monitoring changes in timing of transits of known exoplanets. Nontransiting planets in the system can be inferred from TTVs by their gravitational interactions with the transiting planet. The TTV method is sensitive to low-mass planets that cannot be detected by other means. Inferring the orbital elements and mass of the nontransiting planets from TTVs, however, is more challenging than for other planet detection schemes. It is a difficult inverse problem. Here, we extended the new inversion method proposed by Nesvorny and Morbidelli to eccentric transiting planets and inclined orbits. We found that the TTV signal can be significantly amplified for hierarchical planetary systems with substantial orbital inclinations and/or for an eccentric transiting planet with anti-aligned orbit of the planetary companion. Thus, a fortuitous orbital setup of an exoplanetary system may significantly enhance our chances of TTV detection. We also showed that the detailed shape of the TTV signal is sensitive to the orbital inclination of the nontransiting planetary companion. The TTV detection method may thus provide important constraints on the orbital inclination of exoplanets and be used to test theories of planetary formation and evolution.

  14. Transit Timing Variations for Eccentric and Inclined Exoplanets

    NASA Astrophysics Data System (ADS)

    Nesvorný, David

    2009-08-01

    The Transit Timing Variation (TTV) method relies on monitoring changes in timing of transits of known exoplanets. Nontransiting planets in the system can be inferred from TTVs by their gravitational interactions with the transiting planet. The TTV method is sensitive to low-mass planets that cannot be detected by other means. Inferring the orbital elements and mass of the nontransiting planets from TTVs, however, is more challenging than for other planet detection schemes. It is a difficult inverse problem. Here, we extended the new inversion method proposed by Nesvorný & Morbidelli to eccentric transiting planets and inclined orbits. We found that the TTV signal can be significantly amplified for hierarchical planetary systems with substantial orbital inclinations and/or for an eccentric transiting planet with anti-aligned orbit of the planetary companion. Thus, a fortuitous orbital setup of an exoplanetary system may significantly enhance our chances of TTV detection. We also showed that the detailed shape of the TTV signal is sensitive to the orbital inclination of the nontransiting planetary companion. The TTV detection method may thus provide important constraints on the orbital inclination of exoplanets and be used to test theories of planetary formation and evolution.

  15. Geomorphological control on groundwater flow, transit times and water quality

    NASA Astrophysics Data System (ADS)

    de Dreuzy, Jean-Raynald; Marçais, Jean; Kolbe, Tamara; Courtois, Quentin; Longuevergne, Laurent; Steer, Philippe; Davy, Philippe; Thomas, Zahra; Le Carlier, Christian; Guillocheau, François; Pinay, Gilles

    2017-04-01

    In weathered zones, subsurface flows remain shallow and strongly depend on the geomorphological evolution of the landscape. Weathered profiles have limited depths. Subsurface circulations follow the structure of the hydrological catchment. Surface and subsurface flows are strongly coupled by rapid responses of saturations to recharge. Some of the circulations are indeed fast with surface/subsurface signatures and transit times of the order of some weeks to some months. Most of the water is however much older as revealed by anthropogenic tracers. For example, in the western crystalline basement of France, characteristic transit times are more of the order of decades. Detailed groundwater flow and transport modelling in well-documented sites show that behaviour of weathered zones is intermediary between hydrology and hydrogeology. While organization of flows is strongly constrained by topography like for hydrology, transit times are however much longer like in hydrogeology. Based on several catchments, we propose quantitative indicators to relate geomorphology with subsurface flow organization. We integrate geological constrains and saturation capacities to derive transit-time dynamics. We discuss the consequences on water quality linked to kinetically-controlled degradation of non-point source contaminants.

  16. Educating Part-Time Adult Learners in Transition. ERIC Digest.

    ERIC Educational Resources Information Center

    Conrad, Judi

    Adult learners, who comprise over half of all students in higher education, are typically part-time students in transition and present special challenges to colleges and universities. These students are primarily seeking to improve their situation through education, and their commitment to self-improvement dictates a different set of aspirations…

  17. Transit timing velocimetry /TTV/ for two-phase reacting flows

    SciTech Connect

    Holve, D.J.

    1982-10-01

    A simple single-beam transit timing velocimetry (TTV) method has been developed for determining particle size and mean speed measurements. The method uses a single-beam light scattering system with the addition of two commercial nuclear instrumentation modules to obtain timing information from the trailing edge of the scattering pulses. Results of test studies show that the modal value of transit time remained constant over a wide range of particle sizes, even for particles approaching 50% of the total beam width. Applications of the TTV method to combustion systems include studies of liquid-fuel laminar flames, where integrated reaction times, and thus local droplet velocities, are needed in addition to particle size information.

  18. Time of day and eating behaviors are associated with the composition and function of the human gastrointestinal microbiota.

    PubMed

    Kaczmarek, Jennifer L; Musaad, Salma Ma; Holscher, Hannah D

    2017-09-27

    Background: Preclinical research has shown that the gastrointestinal microbiota exhibits circadian rhythms and that the timing of food consumption can affect the composition and function of gut microbes. However, there is a dearth of knowledge on these relations in humans.Objective: We aimed to determine whether human gastrointestinal microbes and bacterial metabolites were associated with time of day or behavioral factors, including eating frequency, percentage of energy consumed early in the day, and overnight-fast duration.Design: We analyzed 77 fecal samples collected from 28 healthy men and women. Fecal DNA was extracted and sequenced to determine the relative abundances of bacterial operational taxonomic units (OTUs). Gas chromatography-mass spectroscopy was used to assess short-chain fatty acid concentrations. Eating frequency, percentage of energy consumed before 1400, and overnight-fast duration were determined from dietary records. Data were analyzed by linear mixed models or generalized linear mixed models, which controlled for fiber intake, sex, age, body mass index, and repeated sampling within each participant. Each OTU and metabolite were tested as the outcome in a separate model.Results: Acetate, propionate, and butyrate concentrations decreased throughout the day (P = 0.006, 0.04, and 0.002, respectively). Thirty-five percent of bacterial OTUs were associated with time. In addition, relations were observed between gut microbes and eating behaviors, including eating frequency, early energy consumption, and overnight-fast duration.Conclusions: These results indicate that the human gastrointestinal microbiota composition and function vary throughout the day, which may be related to the circadian biology of the human body, the microbial community itself, or human eating behaviors. Behavioral factors, including timing of eating and overnight-fast duration, were also predictive of bacterial abundances. Longitudinal intervention studies are needed to

  19. Transit timing at Toruń Center for Astronomy

    NASA Astrophysics Data System (ADS)

    Bykowski, W.; Maciejewski, G.

    2011-01-01

    The transit monitoring is one of well-known methods for discovering and observing new extrasolar planets. Among various advantages, this way of searching other worlds does not require complex and expensive equipment -- it can be performed with a relatively small telescope and high-quality CCD camera. At the Center for Astronomy of Nicolaus Copernicus University in Toruń, Poland, we collect observational data using the 60-cm Cassegrain telescope hoping that it would be possible to discover new objects in already known planetary systems using the transit timing variation method. Our observations are a part of a bigger cooperation between observatories from many countries.

  20. Radial electron-beam-breakup transit-time oscillator

    SciTech Connect

    Mostrom, M.A.; Kwan, T.J.T.

    1995-01-01

    A new radially-driven electron-beam-breakup transit-time oscillator has been investigated analytically and through computer simulation as a compact low-impedance high-power microwave generator. In a 1MV, 50kA device 35cm in radius and 15cm long, with no external magnetic field, 5GW of extracted power and a growth rate of 0.26/ns have been observed. Theoretical maximum efficiencies are several times higher.

  1. Visual Analysis and Comparison of Kepler Transit Timing Variations with Mutli-Transiting System Applications

    NASA Astrophysics Data System (ADS)

    Kane, Mackenzie; Ragozzine, Darin; Flowers, Xzavier

    2016-10-01

    By noticing the dimming and brightening of the star as an exoplanet transit occurs, NASA's Kepler Space Telescope records the times when the exoplanet passes in front of its star. If other planets are gravitationally influencing the transiting planet, the planet might transit late or early; these deviations from a perfectly periodic set of transits are called transit timing variations (TTVs). Therefore, Kepler TTVs have been very useful in determining exoplanet masses which can be hard to measure in other ways.We visually analyzed the TTV data of all ~6000 Kepler objects of interest (KOIs) to determine whether interesting TTV signals would be missed by purely statistical analyses. Using data from Rowe et al. 2014 and Holczer et al. 2016, we examined TTV plots, periodograms, and folded quadratic+sinusoid fits. To find the most likely KOIs containing visible TTVs and to organize the over 6000 KOIs analyzed, a rating system was developed based on numerous visual factors. By sorting KOIs as such, we were able to compare our findings of the strongest candidates with the same KOIs statistically analyzed by Holczer et al. 2016. It was found that the majority of our findings matched those of Holczer et al. 2016, with only small discrepancies that were understandable based on our different methodologies. Still, our visual inspection of the full list of KOIs contributed multiple planets that were not identified statistically.We combined all of these results with planet properties from the NASA Exoplanet Archive, confirmed and cumulative, to investigate the demographics of planetary systems with and without TTVs. We investigated multi-transiting systems with TTVs not attributable to any of the known planets in the system to better understand exoplanetary system architectures in cases where not all of the planets are transiting.

  2. Colonic transit time in constipated children: does pediatric slow-transit constipation exist?

    PubMed

    Benninga, M A; Büller, H A; Tytgat, G N; Akkermans, L M; Bossuyt, P M; Taminiau, J A

    1996-10-01

    In adults, slow-transit constipation is a well-established form of constipation with abdominal pain and an empty rectum on examination. Marker studies in these patients, mainly women, show a markedly slowed transit time in all colonic segments. No studies in constipated children are available that assess the existence of slow-transit constipation. In a prospective study, a total of 94 referred constipated pediatric patients, 63 boys and 31 girls (median age, 8.0 years), underwent colonic-transit-time measurements using radioopaque markers to evaluate the pattern of transit. In addition, orocecal-transit-time measurements using the hydrogen breath (lactulose) test, anorectal manometry, and behavior studies using the Child Behavior Checklist were performed in all children. Based on the upper limit (mean + 2 SD) of total colonic transit time (CTT) in constipated children, we arbitrarily separated patients into two groups. Children with CTTs > 100 h were said to have pediatric slow-transit constipation (PSTC), while patients with CTTs < 100 h were said to have normal- or delayed-transit constipation (NDTC). In 94 constipated children, PSTC was found in 24 children; in 70 children, total CTT was < 100 h (NDTC). Total and segmental CTTs were significantly prolonged in PSTC (median, 189 h; range, 104.4-384) versus NDTC (median, 46.8 h; range, 3.6-99.4) hours. No significant differences were found in orocecal transit time. Significant clinical differences in children with PSTC versus those with NDTC existed regarding nighttime soiling (71 vs. 11%); daytime soiling episodes (14 vs. 7 each week, median), and nighttime soiling episodes (5 vs. 0 each week, median); absent urge to defecate (33 vs. 14%); and palpable abdominal (71 vs. 39%) and/or rectal (71 vs. 13%) masses. All manometric parameters were comparable in the two groups, except for a significantly lower maximal squeeze pressure with PSTC. Using the Child Behavior Checklist, both groups differed significantly from

  3. Time delay between cardiac and brain activity during sleep transitions

    NASA Astrophysics Data System (ADS)

    Long, Xi; Arends, Johan B.; Aarts, Ronald M.; Haakma, Reinder; Fonseca, Pedro; Rolink, Jérôme

    2015-04-01

    Human sleep consists of wake, rapid-eye-movement (REM) sleep, and non-REM (NREM) sleep that includes light and deep sleep stages. This work investigated the time delay between changes of cardiac and brain activity for sleep transitions. Here, the brain activity was quantified by electroencephalographic (EEG) mean frequency and the cardiac parameters included heart rate, standard deviation of heartbeat intervals, and their low- and high-frequency spectral powers. Using a cross-correlation analysis, we found that the cardiac variations during wake-sleep and NREM sleep transitions preceded the EEG changes by 1-3 min but this was not the case for REM sleep transitions. These important findings can be further used to predict the onset and ending of some sleep stages in an early manner.

  4. Psychiatric and Familial Predictors of Transition Times Between Smoking Stages

    PubMed Central

    Sartor, Carolyn E.; Xian, Hong; Scherrer, Jeffrey F.; Lynskey, Michael T.; Duncan, Alexis E.; Haber, J. Randolph; Grant, Julia D.; Bucholz, Kathleen K.; Jacob, Theodore

    2008-01-01

    The modifying effects of psychiatric and familial risk factors on age at smoking initiation, rate of progression from first cigarette to regular smoking, and transition time from regular smoking to nicotine dependence (ND) were examined in 1,269 offspring of male twins from the Vietnam Era Twin Registry. Mean age of the sample was 20.1 years. Cox proportional hazard regression analyses adjusting for paternal alcohol dependence and ND status and maternal ND were conducted. Both early age at first cigarette and rapid transition from initiation to regular smoking were associated with externalizing disorders, alcohol consumption, and cannabis use. Rapid escalation from regular smoking to ND was also predicted by externalizing disorders, but in contrast to earlier transitions, revealed a strong association with internalizing disorders and no significant relationship with use of other substances. Findings characterize a rarely examined aspect of the course of ND development and highlight critical distinctions in risk profiles across stages of tobacco involvement. PMID:17900819

  5. Red cell pulmonary transit times through the healthy human lung.

    PubMed

    Zavorsky, G S; Walley, K R; Russell, J A

    2003-03-01

    It has previously been postulated that rapid red cell capillary transit through the human lung plays a role in the mechanism of diffusion limitation in some endurance athletes. Methodological limitations currently prevent researchers from directly measuring pulmonary capillary transit times in humans during exercise; however, first pass radionuclide cardiography allows direct measurement of red blood cell (RBC) transit times through the whole lung at various exercise intensities. We examined the relationship between mean whole lung red cell pulmonary transit times (cardiopulmonary transit times or CPTT) and different levels of flow in 88 healthy humans (76 males, 12 females) from several studies (mean age 31 years). The pooled data suggest that the relationship between CPTT and cardiac index (CI), beginning at rest and progressing through to maximum exercise demonstrates that CPTT reaches its minimum value when CI is about 8.1 l m2 x min(-1) (2.5-3 times the CI value at rest), and does not significantly change with further increases in CI. Cardiopulmonary blood volume (CPBV) index also does not change significantly until CI reaches 2.5 to 3 times the CI value at rest and then increases roughly linearly after that point. Consequently, the systematic increase in CPBV index with increasing pulmonary blood flow between 8.1 and 20 l m2 x min(-1) displays an adaptive response of the cardiopulmonary system by augmenting CPBV (and perhaps pulmonary capillary blood volume through distension and recruitment) to offset the reduction in CPTT, as no significant difference in mean CPTT is observed between these levels of flow (P > 0.05). Therefore, these data demonstrate that CPBV does not reach maximum capacity during strenuous or maximum exercise. This does not support the principle of quarter-power allometric scaling for flow when explaining modifications during exercise. Therefore, we speculate that the observed relationships between CPTT, CBPV index and flow may prevent

  6. Transit-timing variations in the system Kepler-410Ab

    NASA Astrophysics Data System (ADS)

    Gajdoš, Pavol; Parimucha, Štefan; Hambálek, Ľubomír; Vaňko, Martin

    2017-08-01

    We present a new analysis of the transit timing variations displayed by the extrasolar planet Kepler-410Ab. We obtained and improved the orbital and physical parameters for the planet and analysed 70 transit times obtained by the Kepler satellite. In our analysis of the O-C diagram (observed minus calculated), we assumed that the observed changes in the transit times are probably caused by the gravitational influence of another body in the system. To determine the mass of the perturbing body, we considered the light-time effect and an analytical approximation of the perturbation model. The solutions resulting from both methods give comparable results, with an orbital period P3 ∼ 970 d and a slightly eccentric orbit of the third body. We also showed that this orbit is nearly coplanar with the orbit of the Neptune-like planet Kepler-410Ab (orbital period 17.8 d). We propose two possible models for the perturbing body orbiting a common barycentre with Kepler-410A: (i) a single star with mass at least 0.906 M⊙, (ii) a binary star with the total mass of its components at least 2.15 M⊙. In both cases, the star Kepler-410B is on a long orbit (period more than 2200 yr). Small amplitude variations (∼5-8 min) detected in O-C residuals can be explained by the stellar activity of the host star (spots and pulsations), which affects the shape of the light curve during the transit. The presence of a single or binary companion of the mentioned masses heavily affects the total observed flux from the system. After removing the flux contamination from the Kepler-410A light curve, we found that the radius of the transiting planet Kepler-410Ab should be in the range from about 3.7 to 4.2 R⊕.

  7. Visual Analysis and Comparison of Kepler Transit Timing Variations

    NASA Astrophysics Data System (ADS)

    Kane, Mackenzie; Ragozzine, Darin; Holczer, Tomer; Mazeh, Tsevi; Rowe, Jason

    2016-01-01

    NASA's Kepler Space Telescope is designed to find extrasolar planets by watching a section of the sky and observing if an object transits in front its parent star. By noticing the dimming and brightening of the star as a prospective transit occurs, Kepler records the times when the planet moves in front of its star. If other planets are gravitationally influencing the transiting planet, the planet might transit late or early; these deviations from a perfectly periodic set of transits are called "transit timing variations (TTVs). Therefore, Kepler TTVs are useful in determining exoplanet masses which are hard to measure in other ways.We decided to visually analyze the TTV data of all ~6000 Kepler objects of interest (KOIs) to determine whether interesting TTV signals would be missed by purely statistical analyses. Using data from Rowe et al. 2014 and Holczer et al. 2015, submitted, we created combined TTV plots, periodigrams, and folded quadratic+sinusoid fits. The raw TTV data and ancillary plots were visually inspected for each of the ~6000 KOIs. To find the most likely KOIs containing visible TTVs and to organize the over 6000 KOIs analyzed, a rating system was developed based on numerous visual factors. These rating factors include the amount of outliers, if there is a clear sinusoidal period within the folded plots, and if there is a clear peak in the periodigram. By sorting KOIs as such, we were able to compare our findings of the strongest candidates with the same KOIs statistically analyzed by Holczer et al. 2015 (submitted, see also Mazeh et al. 2013).It was found that the majority of our findings matched those of Holczer et al. 2015, with only small discrepancies that were understandable based on our different methodologies. Our visual inspection of the full list of KOIs contributed multiple systems that were not included in the initial list of KOIs with significant TTVs identified statistically.

  8. GASTROINTESTINAL EOSINOPHILIA

    PubMed Central

    Zuo, Li; Rothenberg, Marc E.

    2007-01-01

    SYNOPSIS Gastrointestinal eosinophilia, as a broad term for abnormal eosinophil accumulation in the GI tract, involves many different disease identities. These diseases include primary eosinophil associated gastrointestinal diseases, gastrointestinal eosinophilia in HES and all gastrointestinal eosinophilic states associated with known causes. Each of these diseases has its unique features but there is no absolute boundary between them. All three groups of GI eosinophila are described in this chapter although the focus is on primary gastrointestinal eosinophilia, i.e. EGID. PMID:17868858

  9. Time recovery measurements using operational GOES and transit satellites

    NASA Technical Reports Server (NTRS)

    Beehler, R. E.; Davis, D. D.; Cateora, J. V.; Clements, A. J.; Barnes, J. A.; Mendez-Quinones, E.

    1979-01-01

    Results of regular monitoring of both the GOES and TRANSIT timing signals over a number of months at the National Bureau of Standards (NBS), Boulder, Colorado are presented. The TRANSIT results include an analysis of how received timing accuracy and stability are affected by: (1) averaging over varying numbers of satellite passes; (2) averaging over different combinations of the five available satellites; (3) using several independent receivers of the same type; and (4) application of published corrections to the received data. Based on monitoring experience to date at NBS, some pros and cons of using each of the available operational systems are discussed. Updated information on recent improvements incorporated into the GOES time code generation and monitoring system at Wallops Island, Virginia is also included.

  10. Electron transit time measurements of 5-in photomultiplier tubes

    NASA Astrophysics Data System (ADS)

    Richards, T.; Peatross, J.; Ware, M.; Rees, L.

    2016-08-01

    We investigated the uniformity of electron transit times for two 5-in photomultiplier tubes: the Hamamatsu R1250 and the Adit B133D01S. We focused a highly attenuated short-pulse laser on the tubes while they were mounted on a programmable stage. The stage translated the tubes relative to the incident beam so that measurements could be made with light focused at points along a grid covering the entire photocathodes. A portion of the incident light was split from the incident beam and measured and recorded by a fast photodiode. Electron transit times were measured by computing the time delay between the recorded photodiode signal and photomultiplier signal using software constant-fraction discrimination. The Hamamatsu tube exhibited a uniform timing response that varied by no more than 1.7 ns. The Adit tube was much less uniform, with transit times that varied by as much as 57 ns. The Adit response also exhibited a spatially varying double-peak structure in its response. The technique described in this paper could be usefully employed by photomultiplier tube manufacturers to characterize the performance of their products.

  11. In vitro and in vivo survival and transit tolerance of potentially probiotic strains carried by artichokes in the gastrointestinal tract.

    PubMed

    Valerio, Francesca; De Bellis, Palmira; Lonigro, Stella Lisa; Morelli, Lorenzo; Visconti, Angelo; Lavermicocca, Paola

    2006-04-01

    The ability of potentially probiotic strains of Lactobacillus plantarum and Lactobacillus paracasei to survive on artichokes for at least 90 days was shown. The anchorage of bacterial strains to artichokes improved their survival in simulated gastrointestinal digestion. L. paracasei IMPC2.1 was further used in an artichoke human feeding study involving four volunteers, and it was shown that the organism could be recovered from stools.

  12. Time for the Middle to Upper Paleolithic transition in Europe.

    PubMed

    Roebroeks, Wil

    2008-11-01

    The Middle to Upper Paleolithic transition is a key period of change in the prehistory of the Old World and one of the most studied issues in paleoanthropology, as the nature of the transition(s) is still, after at least a century of archaeological research, largely unknown. Many of the issues at stake in the transition relate to the problem of building a reliable chronology for this period, which is at the limits of the radiocarbon method. The papers in this volume show that much progress has been made in our chronological knowledge of significant aspects of the transition, such as the age of the most recent Neandertal fossils and the earliest modern human remains in Europe, and the inferred overlap between the Châtelperronian and the Aurignacian. At the same time, the volume also shows where the chronological database for the period 40 to 30 ka 14C BP is flawed and that significant contextual and methodological problems have been underestimated in a number of studies of the biological and cultural changes during this crucial period. Chronology is employed by paleoanthropologists to relate the record of the Middle to Upper Paleolithic transition to major biological and cultural developments. This paper takes a broader paleoanthropological perspective and attempts to evaluate and, to some degree, synthesize the main results of these proceedings, while also presenting a brief discussion of the Middle and Upper Paleolithic archaeological and fossil records, and possible explanations for the differences between the two, focusing on the role of differences in the ecology of Neandertals and early European modern humans.

  13. Studying time-like baryonic transitions with HADES

    NASA Astrophysics Data System (ADS)

    Ramstein, B.

    2016-05-01

    Recent results of the HADES collaboration are presented with emphasis on the e+e- production in elementary reactions. Via the Dalitz decay of baryonic resonances (R →Ne+e-), access is given to the time-like electromagnetic structure of baryonic transitions. This process could be measured for the first time for Δ(1232) in pp reactions at 1.25 GeV. At higher energies, the sensitivity of e+e- emission to transition form factors of the Vector Dominance type has been demonstrated. Very recently, experiments with the GSI pion beam started, allowing for more direct studies of baryonic resonances Dalitz decays. In addition, the measurement of hadronic channels provides a new data base for baryon spectroscopy issues, in particular in the 2πN channel.

  14. The time of a photoinduced spin-Peierls phase transition

    SciTech Connect

    Semenov, A. L.

    2015-02-15

    The time τ of the spin-Peierls phase transition is analyzed theoretically as a function of the duration τ{sub p} of the exciting light pulse and the average number x{sub 0} of absorbed photons per magnetic ion after the transmission of the pulse. It is shown that the phase transition occurs at x{sub 0} > x{sub c}. The critical value x{sub c} is determined as a function of the duration τ{sub p} of the light pulse. A photoinduced variation in the optical reflection coefficient R is calculated as a function of time t. The results of calculation are compared with experimental data on ultrafast photoinduced melting of the low-temperature spin-Peierls phase into potassium tetracyanoquinodimethan (K-TCNQ)

  15. New contributions to transit-time damping in multidimensional systems

    NASA Technical Reports Server (NTRS)

    Robinson, P. A.

    1989-01-01

    The existence of two previously unrecognized contributions to transit-time damping in systems of more than one dimension is demonstrated and discussed. It is shown that these contributions cannot be treated by one-dimensional analyses unless it is assumed that the gradient of the field perpendicular to itself always vanishes. Such an assumption is unjustified in general and the new contributions can dominate damping by fast particles in more general situations. Analytic expressions obtained using a Born approximation are found to be in excellent agreement with numerical test-particle calculations of transit-time damping for a variety of field configurations. These configurations include those of a resonance layer and of a spherical wave packet, which approximates a collapsing wave packet in a strongly turbulent plasma. It is found that the fractional power absorption can be strongly enhanced in non-slablike field configurations.

  16. Coupling of transit time instabilities in electrostatic confinement fusion devices

    SciTech Connect

    Gruenwald, J. Fröhlich, M.

    2015-07-15

    A model of the behavior of transit time instabilities in an electrostatic confinement fusion reactor is presented in this letter. It is demonstrated that different modes are excited within the spherical cathode of a Farnsworth fusor. Each of these modes is dependent on the fusion products as well as the acceleration voltage applied between the two electrodes and they couple to a resulting oscillation showing non-linear beat phenomena. This type of instability is similar to the transit time instability of electrons between two resonant surfaces but the presence of ions and the occurring fusion reactions alter the physics of this instability considerably. The physics of this plasma instability is examined in detail for typical physical parameter ranges of electrostatic confinement fusion devices.

  17. Tunnel transit-time (TUNNETT) devices for terahertz sources

    NASA Technical Reports Server (NTRS)

    Haddad, G. I.; East, J. R.; Kidner, C.

    1991-01-01

    The potential and capabilities of tunnel transit-time (TUNNETT) devices for power generation in the 100-1000 GHz range are presented. The basic properties of these devices and the important material parameters which determine their properties are discussed and criteria for designing such devices are presented. It is shown from a first-order model that significant amounts of power can be obtained from these devices in the terahertz frequency range.

  18. Watching excitons move: the time-dependent transition density matrix

    NASA Astrophysics Data System (ADS)

    Ullrich, Carsten

    2012-02-01

    Time-dependent density-functional theory allows one to calculate excitation energies and the associated transition densities in principle exactly. The transition density matrix (TDM) provides additional information on electron-hole localization and coherence of specific excitations of the many-body system. We have extended the TDM concept into the real-time domain in order to visualize the excited-state dynamics in conjugated molecules. The time-dependent TDM is defined as an implicit density functional, and can be approximately obtained from the time-dependent Kohn-Sham orbitals. The quality of this approximation is assessed in simple model systems. A computational scheme for real molecular systems is presented: the time-dependent Kohn-Sham equations are solved with the OCTOPUS code and the time-dependent Kohn-Sham TDM is calculated using a spatial partitioning scheme. The method is applied to show in real time how locally created electron-hole pairs spread out over neighboring conjugated molecular chains. The coupling mechanism, electron-hole coherence, and the possibility of charge separation are discussed.

  19. Ergodic transitions in continuous-time random walks

    NASA Astrophysics Data System (ADS)

    Saa, Alberto; Venegeroles, Roberto

    2010-09-01

    We consider continuous-time random walk models described by arbitrary sojourn time probability density functions. We find a general expression for the distribution of time-averaged observables for such systems, generalizing some recent results presented in the literature. For the case where sojourn times are identically distributed independent random variables, our results shed some light on the recently proposed transitions between ergodic and weakly nonergodic regimes. On the other hand, for the case of nonidentical trapping time densities over the lattice points, the distribution of time-averaged observables reveals that such systems are typically nonergodic, in agreement with some recent experimental evidences on the statistics of blinking quantum dots. Some explicit examples are considered in detail. Our results are independent of the lattice topology and dimensionality.

  20. Estimation of liquid volume fraction using ultrasound transit time spectroscopy

    NASA Astrophysics Data System (ADS)

    Al-Qahtani, Saeed M.; Langton, Christian M.

    2016-12-01

    It has recently been proposed that the propagation of an ultrasound wave through complex structures, consisting of two-materials of differing ultrasound velocity, may be considered as an array of parallel ‘sonic rays’, the transit time of each determined by their relative proportion; being a minimum (t min) in entire higher velocity material, and a maximum (t max) in entire lower velocity material. An ultrasound transit time spectrum (UTTS) describes the proportion of sonic rays at an individual transit time. It has previously been demonstrated that the solid volume fraction of a solid:liquid composite, specifically acrylic step-wedges immersed in water, may be reliably estimated from the UTTS. The aim of this research was to investigate the hypothesis that the volume fraction of a two-component liquid mixture, of unequal ultrasound velocity, may also be estimated by UTTS. A through-transmission technique incorporating two 1 MHz ultrasound transducers within a horizontally-aligned cylindrical tube-housing was utilised, the proportion of silicone oil to water being varied from 0% to 100%. The liquid volume fraction was estimated from the UTTS at each composition, the coefficient of determination (R 2%) being 98.9  ±  0.7%. The analysis incorporated a novel signal amplitude normalisation technique to compensate for absorption within the silicone oil. It is therefore envisaged that the parallel sonic ray concept and the derived UTTS may be further applied to the quantification of liquid mixture composition assessment.

  1. Kepler Planet Masses and Eccentricities from Transit Timing Variations

    NASA Astrophysics Data System (ADS)

    Hadden, Sam; Lithwick, Yoram

    2017-01-01

    The Kepler mission’s census of transiting exoplanets has shown that planets between one and four times the radius of Earth with short orbital periods are extremely common. Given their small sizes, the properties of these planets can be difficult or impossible to constrain via radial velocity observations. Mutual gravitational interactions in multi-planet systems induce variations in the arrival times of planets’ transits. These variations can used to probe planets’ masses and eccentricities, which in turn constrain their compositions and formation histories. I will discuss the results of our analysis of the transit timing variations (TTVs) of 145 Kepler planets from 55 multi-planet systems. Bulk densities inferred from TTVs imply that many of these planets are covered in gaseous envelopes ranging from a few percent to ~20% of their total mass. Eccentricities in these systems are small but in a many instances definitively non-zero. These results support theoretical predictions for super-Earth/sub-Neptune planets accreting their envelopes from a depleting proto-planetary disk.

  2. Transit Timing Variations of Resonant Three-planet Systems

    NASA Astrophysics Data System (ADS)

    Libert, Anne-Sophie; Renner, S.

    2012-10-01

    The transit timing variations (TTV) method is a powerful technique to infer the existence of additional non-transiting planets. This is especially the case for resonant systems where the variations can be strongly enhanced. Here we focus on resonant 3-planet systems and assume that the inner body transits the star. We show that the TTV curve exhibits three periodicities related to the resonant evolution of the system. We perform a dynamical study for different mass values of the three planets, with a special attention to the detection of terrestrial planets. A very interesting result is that the existence of two terrestrial companions can be deduced from the TTV curve only. We also highlight the degeneracy in the characterization of non-transiting planets: a system of two giant planets in mean-motion resonance can hide a third terrestrial planet in a multi-resonant configuration. The work of A-S L is supported by an F.R.S.-FNRS Postdoctoral Research Fellowship.

  3. Gastric emptying and intestinal transit times of radiopaque markers in cats fed a high-fiber diet with and without low-dose intravenous diazepam.

    PubMed

    Chandler, M L; Guilford, W G; Lawoko, C R; Whittem, T

    1999-01-01

    Reference ranges for gastric emptying time (GET), small intestinal transit time (SITT), and colonic transit time of 1.5-mm and 5-mm radiopaque markers in healthy cats fed a high-fiber meal were determined, and the influence of low-dose diazepam intravenous injection on the gastrointestinal transit of the markers was examined. The mean GETs and SITTs, and the mean residence times (MRTs) and geometric centers (GCs) of markers in the colon were determined. The effect of intravenous diazepam injection and marker size on these parameters was examined. Diazepam injection had no significant influence on gastrointestinal transit. The GETs of the 1.5-mm markers were significantly more rapid than those of the 5.0-mm markers. There were no significant differences between the SITTs or GCs of the 1.5-mm and 5.0-mm markers. Reference values were developed for GET, SITT, and colonic transit of radiopaque markers for cats fed a high-fiber meal. Diazepam injection had no effect on these parameters.

  4. Food transit time, nutrient digestibility and nitrogen retention in farmed and feral American mink (Neovison vison)--a comparative analysis.

    PubMed

    Gugołek, A; Zalewski, D; Strychalski, J; Konstantynowicz, M

    2013-12-01

    The aim of this study was to determine whether farming leads to changes in gastrointestinal function and nitrogen metabolism in farmed mink (FA), as compared with their wild-living counterparts. Three digestibility and balance trials were carried out. Experiment I was performed in May, and experiments II and III were conducted in September 2011. Farmed mink with the standard coat colour were purchased from a production farm in south-eastern Poland. Feral mink were harvested using cages in the hunting grounds of the Polish Hunting Association, Branch in Olsztyn. The experimental materials comprised of the following: trial I - adult males (eight animals per group), trial II - young females (six animals per group), trial III-young animals (five males and five females per group). Food transit time was measured during digestibility trials, on 10 consecutive days. The coefficients of nutrient and energy digestibility and daily nitrogen balance values were compared between groups in each experiment. It was found that farming contributed to changes in gastrointestinal function and nitrogen metabolism in mink. Farmed animals were characterized by a longer bowel transit time, a tendency towards higher nutrient digestibility and higher nitrogen retention, which resulted from selection for higher productivity.

  5. Masses of Kepler-46b, c from Transit Timing Variations

    NASA Astrophysics Data System (ADS)

    Saad-Olivera, Ximena; Nesvorný, David; Kipping, David M.; Roig, Fernando

    2017-04-01

    We use 16 quarters of the Kepler mission data to analyze the transit timing variations (TTVs) of the extrasolar planet Kepler-46b (KOI-872). Our dynamical fits confirm that the TTVs of this planet (period P={33.648}-0.005+0.004 days) are produced by a non-transiting planet Kepler-46c (P={57.325}-0.098+0.116 days). The Bayesian inference tool MultiNest is used to infer the dynamical parameters of Kepler-46b and Kepler-46c. We find that the two planets have nearly coplanar and circular orbits, with eccentricities ≃ 0.03 somewhat higher than previously estimated. The masses of the two planets are found to be {M}b={0.885}-0.343+0.374 and {M}c={0.362}-0.016+0.016 Jupiter masses, with M b being determined here from TTVs for the first time. Due to the precession of its orbital plane, Kepler-46c should start transiting its host star a few decades from now.

  6. Evaluation of reference genes for real-time PCR studies of Brazilian Somalis sheep infected by gastrointestinal nematodes

    PubMed Central

    2010-01-01

    Precise normalization with reference genes is necessary, in order to obtain reliable relative expression data in response to gastrointestinal nematode infection. By using sheep from temperate regions as models, three reference genes, viz., ribosomal protein LO (RPLO), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and succinate dehydrogenase complex subunit A (SDHA), were investigated in the abomasum, abomasal lymph nodes and small intestine of Brazilian Somalis sheep, either resistant or susceptible to gastrointestinal nematodes infections. Real time PCR was carried out by using SYBR Green I dye, and gene stability was tested by geNorm. RPLO was an ideal reference gene, since its expression was constant across treatments, presented lower variation, and was ranked as the most stable in abomasum and lymph node tissues. On the other hand, SDHA was the most stable in the small intestine followed by RPLO and GAPDH. These findings demonstrate the importance of correctly choosing reference genes prior to relative quantification. In addition, we determined that reference genes used in sheep from temperate regions, when properly tested, can be applied in animals from tropical regions such as the Brazilian Somalis sheep. PMID:21637421

  7. Predictable patterns in planetary transit timing variations and transit duration variations due to exomoons

    NASA Astrophysics Data System (ADS)

    Heller, René; Hippke, Michael; Placek, Ben; Angerhausen, Daniel; Agol, Eric

    2016-06-01

    We present new ways to identify single and multiple moons around extrasolar planets using planetary transit timing variations (TTVs) and transit duration variations (TDVs). For planets with one moon, measurements from successive transits exhibit a hitherto undescribed pattern in the TTV-TDV diagram, originating from the stroboscopic sampling of the planet's orbit around the planet-moon barycenter. This pattern is fully determined and analytically predictable after three consecutive transits. The more measurements become available, the more the TTV-TDV diagram approaches an ellipse. For planets with multiple moons in orbital mean motion resonance (MMR), like the Galilean moon system, the pattern is much more complex and addressed numerically in this report. Exomoons in MMR can also form closed, predictable TTV-TDV figures, as long as the drift of the moons' pericenters is sufficiently slow. We find that MMR exomoons produce loops in the TTV-TDV diagram and that the number of these loops is equal to the order of the MMR, or the largest integer in the MMR ratio. We use a Bayesian model and Monte Carlo simulations to test the discoverability of exomoons using TTV-TDV diagrams with current and near-future technology. In a blind test, two of us (BP, DA) successfully retrieved a large moon from simulated TTV-TDV by co-authors MH and RH, which resembled data from a known Kepler planet candidate. Single exomoons with a 10% moon-to-planet mass ratio, like to Pluto-Charon binary, can be detectable in the archival data of the Kepler primary mission. Multi-exomoon systems, however, require either larger telescopes or brighter target stars. Complementary detection methods invoking a moon's own photometric transit or its orbital sampling effect can be used for validation or falsification. A combination of TESS, CHEOPS, and PLATO data would offer a compelling opportunity for an exomoon discovery around a bright star.

  8. Predictable Patterns in Planetary Transit Timing Variations and Transit Duration Variations Due to Exomoons

    NASA Technical Reports Server (NTRS)

    Heller, Rene; Hippke, Michael; Placek, Ben; Angerhausen, Daniel; Agol, Eric

    2016-01-01

    We present new ways to identify single and multiple moons around extrasolar planets using planetary transit timing variations (TTVs) and transit duration variations (TDVs). For planets with one moon, measurements from successive transits exhibit a hitherto undescribed pattern in the TTV-TDV diagram, originating from the stroboscopic sampling of the planet's orbit around the planet-moon barycenter. This pattern is fully determined and analytically predictable after three consecutive transits. The more measurements become available, the more the TTV-TDV diagram approaches an ellipse. For planets with multiple moons in orbital mean motion resonance (MMR), like the Galilean moon system, the pattern is much more complex and addressed numerically in this report. Exomoons in MMR can also form closed, predictable TTV-TDV figures, as long as the drift of the moons' pericenters is suciently slow.We find that MMR exomoons produce loops in the TTV-TDV diagram and that the number of these loops is equal to the order of the MMR, or the largest integer in the MMR ratio.We use a Bayesian model and Monte Carlo simulations to test the discoverability of exomoons using TTV-TDV diagrams with current and near-future technology. In a blind test, two of us (BP, DA) successfully retrieved a large moon from simulated TTV-TDV by co-authors MH and RH, which resembled data from a known Kepler planet candidate. Single exomoons with a 10 percent moon-to-planet mass ratio, like to Pluto-Charon binary, can be detectable in the archival data of the Kepler primary mission. Multi-exomoon systems, however, require either larger telescopes or brighter target stars. Complementary detection methods invoking a moon's own photometric transit or its orbital sampling effect can be used for validation or falsification. A combination of TESS, CHEOPS, and PLATO data would offer a compelling opportunity for an exomoon discovery around a bright star.

  9. Detection and Characterization of Non-Transiting Planets from Transit Timing Variations

    NASA Astrophysics Data System (ADS)

    Nesvorny, David; Kipping, David; Terrell, Dirk

    2014-11-01

    The Transit Timing Variations (TTVs) can be used as a diagnostic of gravitational interactions between planets in a multi-planet system. Here we conduct a photo-dynamical analysis of several Kepler Objects of Interest (KOIs) that exhibit significant TTVs. We show that KOI-142, KOI-227 and KOI-319 are (at least) two planet systems. KOI-142.01's TTVs uniquely detect a non-transiting companion with a mass 0.63 that of Jupiter. KOI-142.01's mass inferred from the TTVs is consistent with the measured transit depth, suggesting a Neptune-class planet. The orbital period ratio 2.03 indicates that the two planets are just wide of the 2:1 resonance. For KOI-319 and KOI-884, the observed TTVs of the inner transiting planet are used to detect an outer non-transiting planet. The outer planet in KOI-884 is 2.6 Jupiter masses and has the orbital period just narrow of the 3:1 resonance with the inner planet (orbital period ratio 2.93). The distribution of parameters inferred from KOI-319.01's TTVs is bimodal with either a 1.6 Neptune-mass planet wide of the 5:3 resonance (period 80.1 d) or a Saturn-mass planet wide of the 7:3 resonance (period 109.2 d). The radial velocity measurements can be used in this case to determine which of these parameter modes is correct. We discuss how the orbital architecture of KOI-142, KOI-227 and KOI-319 systems constrains their formation.

  10. Radiopaque markers to evaluate gastric emptying and small intestinal transit time in healthy cats.

    PubMed

    Chandler, M L; Guilford, G; Lawoko, C R

    1997-01-01

    Determinations of gastric emptying time (GET) and small intestinal transit time (SITT) are useful in detecting gastrointestinal motility disorders and partial obstructions of the pylorus or small intestine. Barium-impregnated, polyethylene radiopaque spheres with diameters of 1.5 mm and 5.0 mm have been developed for quantitative assessment of gastrointestinal transit. The purpose of this study was to evaluate GET and SITT using these radiopaque spheres in 10 healthy cats. The cats were randomly assigned to 1 of 3 treatment groups: fasted, fed, and fed plus sedation (acetylpromazine maleate 0.10 mg/kg subcutaneously). A repeated measures study design was used. The mean GETs of 50%, 75%, and 90% of the 1.5-mm and the 5-mm spheres in the unfed cats were 0.36, 0.58, and 0.74 hours, and 0.41, 0.68, and 1.02 hours, respectively. These values were significantly (P < or = .05) more rapid than the GETs of 50%, 75%, and 90% of the 1.5-mm and 5-mm spheres of either the sedated fed cats (4.39, 5.68, 6.65 and 5.15, 5.99, 6.91 hours) or the unsedated fed cats (6.43, 8.12, 9.06 and 7.49, 8.49, 9.22 hours). The mean GETs of 50% and 75% of the 1.5-mm and 5-mm and of 90% of the 1.5-mm spheres were significantly (P < or = .05) more rapid in sedated than in unsedated fed cats. The GET of 50% of the 1.5-mm spheres was significantly more rapid (P < or = .05) than that of the 5-mm spheres in the fed cats. The mean SITTs, which ranged from 2.25 to 3.05 hours, were not significantly different (P > .05) among the treatment groups or between the 1.5-mm and 5-mm spheres. The GET of spheres given to fasted cats is significantly more rapid than that of fed cats. Subcutaneous injection of acetylpromazine speeds GET in fed cats. The SITT of small and large spheres was not influenced by feeding or by acetylpromazine injection.

  11. The scintigraphic determination of small intestinal transit time in patients with irritable bowel syndrome

    SciTech Connect

    Marano, A.R.; Caride, V.J.; Shah, R.V.; Prokop, E.K.; Troncale, F.J.; McCallum, R.W.

    1984-01-01

    Diffuse disturbance in gastrointestinal motility may be present in patients with irritable bowel syndrome (IBS). To further investigate small intestinal motility in IBS patients small intestinal transit time (SITT) was determined and related to the symptom status. 11 female patients with IBS (mean age 29 years) were divided into those whose predominate symptom was diarrhea (N=6), and those with only constipation (N=5). All subjects ingested an isosmotic solution of lactulose (10 gm in 150cc of water) labeled with 99m-Tc-DTPA (Sn). The patient was studied supine under a 25 inch gamma camera with data collected at 1 frame per minute for 180 minutes or until activity appeared in the ascending colon. Regions of interest were selected over the cecum and ascending colon. The time of first appearance of radioactivity in the region of the cecum was taken as the small intestinal transit time. SITT in the 5 normal females was 98.7 +- 13 min (mean +- SEM). SITT in the IBS patients with diarrhea, 67.3 +- 7 min was significantly faster (p< 0.08). SITT in the constipated IBS patients, 126 +- 12 min, was slower than normals and significantly different from diarrhea patients (p< 0.001). These studies show that IBS patients with diarrhea have significantly faster SITT than normals while constipated IBS patients have significantly slower SITT than the diarrhea subgroup. Further, this study emphasizes the need to study the various symptomatic subgroups of IBs patients independently and indicates a possible role for abnormal SITT in the pathogenesis of IBS.

  12. Measuring Interior Properties of Very Hot Jupiters Through Transit Timing

    NASA Astrophysics Data System (ADS)

    Ragozzine, Darin; Wolf, A. S.

    2008-05-01

    The radius of an extra-solar planet is measured photometrically when the planet transits its parent star. Many of these planets have anomalously large radii, while others are extremely compact. Despite many theoretical efforts, these radius anomalies are still unexplained, though they clearly depend on the diversity of planetary interiors. We show that the currently unknown interior properties of extra-solar planets can be directly measured by observing the orbital precession induced by the quadrupole moment of the planet as evidenced by subtle but observable changes in the transit light curves (Ragozzine & Wolf, 2008, ApJ, pending submission). Other authors have suggested using transit timing to observe the effects of general relativity, stellar oblateness, or additional planets in the system. We show that precession due to the quadrupole moment of the planet dominates over other perturbations by 1-2 orders of magnitude in the case of single very hot Jupiters (a ≃ 0.02 AU). We assess the realistic measurement accuracy of extra-solar gravitational moments (e.g. J2) and find that it is a sensitive function of eccentricity, but clearly measurable for reasonable eccentricities (e < 0.01). We will discuss the capabilities of this new technique to directly characterize the diversity of extra-solar planet interiors in light of future observations, particularly those provided by the Kepler space-based photometry mission.

  13. Controllability of timed continuous Petri nets with uncontrollable transitions

    NASA Astrophysics Data System (ADS)

    Vázquez, C. Renato; Ramírez-Treviño, Antonio; Silva, Manuel

    2014-03-01

    This paper is concerned with controllability of Timed Continuous Petri nets, under infinite server semantics, with uncontrollable transitions, which are a class of hybrid systems (piecewise-linear). This class of hybrid systems is suitable for representing biological systems, high traffic information networks, heavily loaded supply chains, etc. By adopting a Control Theory approach, the contribution of this paper is the characterisation of controllability over sets of equilibrium markings (potential equilibrium points), first inside a single marking region (or linear mode) and later extended to several regions.

  14. Numerical and Analytical Modeling of Transit Timing Variations

    NASA Astrophysics Data System (ADS)

    Hadden, Sam; Lithwick, Yoram

    2016-09-01

    We develop and apply methods to extract planet masses and eccentricities from observed transit timing variations (TTVs). First, we derive simple analytic expressions for the TTV that include the effects of both first- and second-order resonances. Second, we use N-body Markov chain Monte Carlo simulations, as well as the analytic formulae, to measure the masses and eccentricities of 10 planets discovered by Kepler that have not previously been analyzed. Most of the 10 planets have low densities. Using the analytic expressions to partially circumvent degeneracies, we measure small eccentricities of a few percent or less.

  15. Times of transition: elder abuse and neglect in Israel.

    PubMed

    Lowenstein, Ariela; Doron, Israel

    2008-01-01

    The present paper addresses the advancement of research, policies, legislation, and practice experiences designed to deal with the phenomenon of elder abuse and neglect in Israel in times of transition. The paper presents a short overview of the demographic scene, reflecting population characteristics and needs that impact care giving as well as elder abuse and neglect. The developments of scientific knowledge and its accumulation, especially the empirical data from the first national survey on elder abuse and neglect are discussed. Further, legislative developments relating to four generational laws and the advancement of policies and innovative practice experiences are described and analyzed. Finally, future challenges in the field are identified.

  16. Radial electron-beam-breakup transit-time oscillator

    DOEpatents

    Kwan, Thomas J. T.; Mostrom, Michael A.

    1998-01-01

    A radial electron-beam-breakup transit-time oscillator (RBTO) provides a compact high power microwave generator. The RBTO includes a coaxial vacuum transmission line having an outer conductor and an inner conductor. The inner conductor defines an annular cavity with dimensions effective to support an electromagnetic field in a TEM.sub.00m mode. A radial field emission cathode is formed on the outer conductor for providing an electron beam directed toward the annular cavity electrode. Microwave energy is then extracted from the annular cavity electrode.

  17. A new approach to determine time variant catchment transit times and their time distribution based on field data

    NASA Astrophysics Data System (ADS)

    Klaus, Julian; Pan Chun, Kwok; McGuire, Kevin J.; McDonnell, Jeffrey J.

    2014-05-01

    Mean transit times (MTT) and their transit time distributions (TTD) are a physical measure integrating all catchment processes, flow path variability, and the combined effects of water storage and water fluxes. The traditional approach for quantifying MTT and TTD of stream water is based on the convolution integral that relates the input and the output of a conservative tracer time series with a transfer function that determines the shape of the TTD. The main limitation with this standard approach is that convolution overlooks the temporal dynamics of water flow paths and their changing distributions through time. Despite recent progress, we still lack an approach for determining TT and TTD based on field data; one that accounts for the new theoretical developments and understanding, but also embraces the time series of isotope data that an experimentalist might have from an experimental watershed. Here we introduce a new, simple approach for calculating time-varying TT and TTD based on measured tracer input and output data and the hydrological fluxes from a catchment. Our approach is designed to account for time variance in the transit time and the transit time distribution and the irregular shape of the transit time distribution. The objectives for this presentation are to (1) demonstrate the conceptual background and the validation of the approach in a proof of concept with artificial data (2) and apply it to an actual dataset from the well-characterized WS10 in the HJA Experimental Forest, Oregon, USA. Applied to a virtual data set the model reproduces known isotope values and transit times with a Nash-Sutcliffe efficiency (NSE) of over 0.9, while it reproduces the observed 18Oxygen signatures in WS10 with a NSE of 0.86. Transit time in WS 10 varies between approximately 250 and 550 days. The transit time distributions are highly irregular in shape; these distributions do not follow a predetermined distribution such as the gamma or exponential distributions

  18. Relationship between systemic drug absorption and gastrointestinal transit after the simultaneous oral administration of carbamazepine as a controlled-release system and as a suspension of 15N-labelled drug to healthy volunteers.

    PubMed

    Wilding, I R; Davis, S S; Hardy, J G; Robertson, C S; John, V A; Powell, M L; Leal, M; Lloyd, P; Walker, S M

    1991-11-01

    1. Plasma drug concentrations after a single oral administration of a suspension of carbamazepine (CBZ) and a 20/200 CBZ Oros osmotic pump system were measured in eight healthy male volunteers. The oral suspension contained 100 mg CBZ labelled with the stable isotope nitrogen-15, whilst the Oros contained 200 mg unlabelled CBZ. Plasma concentrations of [15N]-CBZ and CBZ were measured simultaneously by gas chromatography-mass spectrometry. 2. The position of the CBZ Oros (labelled with indium-111) in the gastrointestinal tract was followed by gamma scintigraphy. Plasma drug concentrations after the two treatments were used to relate pharmacokinetic with transit data. 3. The Oros was taken after breakfast and gastric emptying occurred between 1.1- greater than h post-dosing (median, 5.3 h). Small intestinal transit times ranged from 1.5- greater than 3.6 h, with a median of 2.2 h. There were wide individual variations in colonic transit, and the total transit time ranged from 10-60 h (median, 22 h). 4. Relative systemic bioavailability of CBZ from the Oros was reduced compared with that from the suspension (mean dose normalised AUC ratio = 0.69 +/- 0.17; mean dose-normalised AUC ratio = 0.85 +/- 0.13, allowing for actual release from the Oros system). 5. The in vivo absorption of drug into the systemic circulation from the Oros was estimated using the Wagner-Nelson method. This showed that absorption of CBZ was rapid when the Oros was present in the stomach and small intestine, the rate being determined by the release of drug from the system.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Delivering on the promise of transit timing variations

    NASA Astrophysics Data System (ADS)

    Agol, Eric; Deck, Katherine

    2015-01-01

    Transiting timing variations (TTVs) have held the promise of enabling the measurement of planet masses and radii in multi-transiting planet systems found with the Kepler spacecraft. However, when a single TTV frequency is detected, a degeneracy commonly exists between the eccentricities and masses of the planets (Lithwick, Xie & Wu 2012), making the masses and eccentricities indeterminate. In some cases this degeneracy has been broken with n-body integrations, but this enshrouds the answer in complex numerics. It may also be broken statistically, but this still does not provide measurements for individual planets.We show how this degeneracy may be broken with a measurement of TTV at the synodic frequency, which has an amplitude that depends strongly on the planet-star mass ratios and on the planets' semi-major axis ratio, yet weakly on their eccentricities. This "chopping" signal is generally modest in amplitude, but when it is detected it can provide the primary constraint upon planet masses, such as in Kepler 11d&e and KOI-872c. We show by example how harmonic analysis of TTVs combined with analytic formulae can break the eccentricity-mass degeneracy without the need for dynamical integrations, thus delivering on the promise of TTVs, while at the same time clarifying the origin of the planetary mass constraints resulting from TTV analysis.

  20. Analytical approximation of transit time scattering due to magnetosonic waves

    NASA Astrophysics Data System (ADS)

    Bortnik, J.; Thorne, R. M.; Ni, B.; Li, J.

    2015-03-01

    Recent test particle simulations have shown that energetic electrons traveling through fast magnetosonic (MS) wave packets can experience an effect which is specifically associated with the tight equatorial confinement of these waves, known as transit time scattering. However, such test particle simulations can be computationally cumbersome and offer limited insight into the dominant physical processes controlling the wave-particle interactions, that is, in determining the effects of the various wave parameters and equatorial confinement on the particle scattering. In this paper, we show that such nonresonant effects can be effectively captured with a straightforward analytical treatment that is made possible with a set of reasonable, simplifying assumptions. It is shown that the effect of the wave confinement, which is not captured by the standard quasi-linear theory approach, acts in such a way as to broaden the range of particle energies and pitch angles that can effectively resonate with the wave. The resulting diffusion coefficients can be readily incorporated into global diffusion models in order to test the effects of transit time scattering on the dynamical evolution of radiation belt fluxes.

  1. Excitation signal's influence on ultrasonic transit time flow meter's performance

    NASA Astrophysics Data System (ADS)

    Svilainis, L.; Kabisius, P.; Aleksandrovas, A.; Chaziachmetovas, A.

    2012-12-01

    Ultrasonic flow meter performance was analyzed. Ultrasound transit time was used for flow rate estimation. Time of flight was measured using cross correlation processing. Simultaneous channels excitation was used. Ultrasonic signals were excited using low voltage (4V pp) signal generator, received signals were amplified 30 dB and simultaneously acquired by 100 Ms/s 10 bit analog-to-digit converters. Subsample delay estimation was used. Flow rate was varied from 10 l/h to 200 l/h. Measurement channel diameter 8 mm was used. It is complicated to obtain the unbiased reference signal for correlation processing. Various combinations of signals travelling in measurement channel were used for cross-correlation processing. Performance of correlation function and time of flight estimator variance were studied. Variable gain amplifier usually is used for signal dynamic range matching to A/D converter input. Gain influence on time of flight was a subject to study. It has been concluded that gain control introduces systematic errors in time of flight estimator. Influence of the temperature of electronics (pulser, receiver, A/D converter, reference clock etc.) and ultrasonic transducers on the delay estimator was studied. It was concluded that the major temperature-related systematic error comes from the pulser. Performance of the meter was studied when narrowband and spread spectrum signals were used for ultrasound excitation across temperature and flow rate range. It has been concluded that spread spectrum signal allows for better zero flow stability over temperature and lower time of flight variation.

  2. Cardiovascular and gastrointestinal radiographic contrast studies in the horseshoe crab (Limulus polyphemus).

    PubMed

    Spotswood, Tim; Smith, Stephen A

    2007-01-01

    Survey and contrast radiographic studies of the cardiovascular and gastrointestinal systems of the American horseshoe crab (Limulus polyphemus) were undertaken using conventional and flouroscopic techniques. Normal gastrointestinal and cardiovascular structures were difficult to resolve on survey radiographs, but were well visualized with gastrointestinal follow through studies and angiography, respectively. All three contrast agents (iohexol, Gastrografin, and barium sulfate) used for the gastrointestinal studies varied minimally in their radiographic quality and transit times, and all appeared to be safe for use in the horseshoe crab.

  3. The length and time scales of water's glass transitions.

    PubMed

    Limmer, David T

    2014-06-07

    Using a general model for the equilibrium dynamics of supercooled liquids, I compute from molecular properties the emergent length and time scales that govern the nonequilibrium relaxation behavior of amorphous ice prepared by rapid cooling. Upon cooling, the liquid water falls out of equilibrium whereby the temperature dependence of its relaxation time is predicted to change from super-Arrhenius to Arrhenius. A consequence of this crossover is that the location of the apparent glass transition temperature depends logarithmically on cooling rate. Accompanying vitrification is the emergence of a dynamical length-scale, the size of which depends on the cooling rate and varies between angstroms and tens of nanometers. While this protocol dependence clarifies a number of previous experimental observations for amorphous ice, the arguments are general and can be extended to other glass forming liquids.

  4. Space and time renormalization in phase transition dynamics

    DOE PAGES

    Francuz, Anna; Dziarmaga, Jacek; Gardas, Bartłomiej; ...

    2016-02-18

    Here, when a system is driven across a quantum critical point at a constant rate, its evolution must become nonadiabatic as the relaxation time τ diverges at the critical point. According to the Kibble-Zurek mechanism (KZM), the emerging post-transition excited state is characterized by a finite correlation length ξˆ set at the time tˆ=τˆ when the critical slowing down makes it impossible for the system to relax to the equilibrium defined by changing parameters. This observation naturally suggests a dynamical scaling similar to renormalization familiar from the equilibrium critical phenomena. We provide evidence for such KZM-inspired spatiotemporal scaling by investigatingmore » an exact solution of the transverse field quantum Ising chain in the thermodynamic limit.« less

  5. Space and time renormalization in phase transition dynamics

    SciTech Connect

    Francuz, Anna; Dziarmaga, Jacek; Gardas, Bartłomiej; Zurek, Wojciech H.

    2016-02-18

    Here, when a system is driven across a quantum critical point at a constant rate, its evolution must become nonadiabatic as the relaxation time τ diverges at the critical point. According to the Kibble-Zurek mechanism (KZM), the emerging post-transition excited state is characterized by a finite correlation length ξˆ set at the time tˆ=τˆ when the critical slowing down makes it impossible for the system to relax to the equilibrium defined by changing parameters. This observation naturally suggests a dynamical scaling similar to renormalization familiar from the equilibrium critical phenomena. We provide evidence for such KZM-inspired spatiotemporal scaling by investigating an exact solution of the transverse field quantum Ising chain in the thermodynamic limit.

  6. Cerenkov and transition radiation in space-time periodic media.

    NASA Technical Reports Server (NTRS)

    Elachi, C.

    1972-01-01

    The solution to the problem of determining the radiation emitted by a uniformly moving charged particle in a sinusoidally space-time periodic medium is obtained. The space-time periodicity can be considered as due to a strong pump wave and is expressed as a traveling-wave-type change in the dielectric constant or the plasma density. The solution covers also the limiting case of sinusoidally stratified media. The expression and spectrum of the radiated electromagnetic field are determined for different media: dielectric, isotropic and uniaxial plasma. Depending on the nature of the medium and the velocity of the particle, the radiated field is of the Cerenkov and/or transition type. The Brillouin diagram is used extensively in understanding and determining the nature, extent, and spectrum of the different modes of radiation, and a focusing effect is also studied.

  7. Daylight saving time transitions and acute myocardial infarction.

    PubMed

    Čulić, Viktor

    2013-06-01

    Most recently, the possible impact of transitions to and from daylight saving time (DST) on the increased incidence of acute myocardial infarction (AMI) has been suggested. The goal of this report was to analyze independent influence of DST transitions on the incidence of AMI with simultaneous control for the confounding presence of situational triggers such as physical exertion, emotional stress, heavy meals, and sexual intercourse, as well as for other clinical factors. Detailed information was obtained from 2412 patients and included baseline characteristics, working status, exact time of AMI, possible external triggers, cardiovascular risk factors, and prehospital medication. AMI incidence on days after the DST was compared with incidence during control periods and patient characteristics, cardiovascular medication, and circumstances of AMI were evaluated to identify potential risk modifiers. Relative risks of AMI and differences in patient characteristics were expressed through incidence ratios and odds ratios, respectively, with 95% confidence intervals (CIs). Multivariate analysis was performed by using a stepwise multiple regression to assess the independent predictive significance of the characteristics of patients for the AMI occurring in the posttransitional period. The incidence ratio for AMI for the first four workdays after the spring DST transition was 1.29 (95% CI: 1.09-1.49) and the excess was particularly prominent on Monday. In autumn, the incidence ratio for AMI for this 4-d period was 1.44 (95% CI: 1.19-1.69), with peaks on Tuesday and Thursday. The independent predictors for AMI during this period in spring were male sex (p = 0.03) and nonengagement in physical activity (p = 0.02) and there was a trend for the lower risk of incident among those taking calcium antagonists (p = 0.07). In autumn, the predictors were female sex (p = 0.04), current employment (p = 0.006), not taking β-blocker (p = 0.03), and nonengagement in physical activity (p

  8. Drinking water residence time in distribution networks and emergency department visits for gastrointestinal illness in Metro Atlanta, Georgia.

    PubMed

    Tinker, Sarah C; Moe, Christine L; Klein, Mitchel; Flanders, W Dana; Uber, Jim; Amirtharajah, Appiah; Singer, Philip; Tolbert, Paige E

    2009-06-01

    We examined whether the average water residence time, the time it takes water to travel from the treatment plant to the user, for a zip code was related to the proportion of emergency department (ED) visits for gastrointestinal (GI) illness among residents of that zip code. Individual-level ED data were collected from all hospitals located in the five-county metro Atlanta area from 1993 to 2004. Two of the largest water utilities in the area, together serving 1.7 million people, were considered. People served by these utilities had almost 3 million total ED visits, 164,937 of them for GI illness. The relationship between water residence time and risk for GI illness was assessed using logistic regression, controlling for potential confounding factors, including patient age and markers of socioeconomic status (SES). We observed a modestly increased risk for GI illness for residents of zip codes with the longest water residence times compared with intermediate residence times (odds ratio (OR) for Utility 1 = 1.07, 95% confidence interval (CI) = 1.03, 1.10; OR for Utility 2 = 1.05, 95% CI = 1.02, 1.08). The results suggest that drinking water contamination in the distribution system may contribute to the burden of endemic GI illness.

  9. Drinking Water Residence Time in Distribution Networks and Emergency Department Visits for Gastrointestinal Illness in Metro Atlanta, Georgia

    PubMed Central

    Moe, Christine L.; Klein, Mitchel; Flanders, W. Dana; Uber, Jim; Amirtharajah, Appiah; Singer, Philip; Tolbert, Paige E.

    2013-01-01

    We examined whether the average water residence time, the time it takes water to travel from the treatment plant to the user, for a zip code was related to the proportion of emergency department (ED) visits for gastrointestinal (GI) illness among residents of that zip code. Individual-level ED data were collected from all hospitals located in the five-county metro Atlanta area from 1993 to 2004. Two of the largest water utilities in the area, together serving 1.7 million people, were considered. People served by these utilities had almost three million total ED visits, 164,937 of them for GI illness. The relationship between water residence time and risk for GI illness was assessed using logistic regression, controlling for potential confounding factors, including patient age and markers of socioeconomic status (SES). We observed a modestly increased risk for GI illness for residents of zip codes with the longest water residence times compared to intermediate residence times (odds ratio (OR) for Utility 1 = 1.07, 95% confidence interval (CI) = 1.03, 1.10; OR for Utility 2 = 1.05, 95% CI = 1.02, 1.08). The results suggest that drinking water contamination in the distribution system may contribute to the burden of endemic GI illness. PMID:19240359

  10. RSRM Chamber Pressure Oscillations: Transit Time Models and Unsteady CFD

    NASA Technical Reports Server (NTRS)

    Nesman, Tom; Stewart, Eric

    1996-01-01

    Space Shuttle solid rocket motor low frequency internal pressure oscillations have been observed since early testing. The same type of oscillations also are present in the redesigned solid rocket motor (RSRM). The oscillations, which occur during RSRM burn, are predominantly at the first three motor cavity longitudinal acoustic mode frequencies. Broadband flow and combustion noise provide the energy to excite these modes at low levels throughout motor burn, however, at certain times during burn the fluctuating pressure amplitude increases significantly. The increased fluctuations at these times suggests an additional excitation mechanism. The RSRM has inhibitors on the propellant forward facing surface of each motor segment. The inhibitors are in a slot at the segment field joints to prevent burning at that surface. The aft facing segment surface at a field joint slot burns and forms a cavity of time varying size. Initially the inhibitor is recessed in the field joint cavity. As propellant burns away the inhibitor begins to protrude into the bore flow. Two mechanisms (transit time models) that are considered potential pressure oscillation excitations are cavity-edge tones, and inhibitor hole-tones. Estimates of frequency variation with time of longitudinal acoustic modes, cavity edge-tones, and hole-tones compare favorably with frequencies measured during motor hot firing. It is believed that the highest oscillation amplitudes occur when vortex shedding frequencies coincide with motor longitudinal acoustic modes. A time accurate computational fluid dynamic (CFD) analysis was made to replicate the observations from motor firings and to observe the transit time mechanisms in detail. FDNS is the flow solver used to detail the time varying aspects of the flow. The fluid is approximated as a single-phase ideal gas. The CFD model was an axisymmetric representation of the RSRM at 80 seconds into burn.Deformation of the inhibitors by the internal flow was determined

  11. TRANSIT TIMING VARIATIONS FOR INCLINED AND RETROGRADE EXOPLANETARY SYSTEMS

    SciTech Connect

    Payne, Matthew J.; Ford, Eric B.; Veras, Dimitri

    2010-03-20

    We perform numerical calculations of the expected transit timing variations (TTVs) induced on a hot-Jupiter by an Earth-mass perturber. Motivated by the recent discoveries of retrograde transiting planets, we concentrate on an investigation of the effect of varying relative planetary inclinations, up to and including completely retrograde systems. We find that planets in low-order (e.g., 2:1) mean-motion resonances (MMRs) retain approximately constant TTV amplitudes for 0 deg. < i < 170 deg., only reducing in amplitude for i>170 deg. Systems in higher order MMRs (e.g., 5:1) increase in TTV amplitude as inclinations increase toward 45 deg., becoming approximately constant for 45 deg. < i < 135 deg., and then declining for i>135 deg. Planets away from resonance slowly decrease in TTV amplitude as inclinations increase from 0 deg. to 180 deg., whereas planets adjacent to resonances can exhibit a huge range of variability in TTV amplitude as a function of both eccentricity and inclination. For highly retrograde systems (135 deg. < i {<=} 180 deg.), TTV signals will be undetectable across almost the entirety of parameter space, with the exceptions occurring when the perturber has high eccentricity or is very close to an MMR. This high inclination decrease in TTV amplitude (on and away from resonance) is important for the analysis of the known retrograde and multi-planet transiting systems, as inclination effects need to be considered if TTVs are to be used to exclude the presence of any putative planetary companions: absence of evidence is not evidence of absence.

  12. Discrimination of Gastrointestinal Nematode Eggs from Crude Fecal Egg Preparations by Inhibitor-Resistant Conventional and Real-Time PCR

    PubMed Central

    Demeler, Janina; Ramünke, Sabrina; Wolken, Sonja; Ianiello, Davide; Rinaldi, Laura; Gahutu, Jean Bosco; Cringoli, Giuseppe; von Samson-Himmelstjerna, Georg; Krücken, Jürgen

    2013-01-01

    Diagnosis of gastrointestinal nematodes relies predominantly on coproscopic methods such as flotation, Kato-Katz, McMaster or FLOTAC. Although FLOTAC allows accurate quantification, many nematode eggs can only be differentiated to genus or family level. Several molecular diagnostic tools discriminating closely related species suffer from high costs for DNA isolation from feces and limited sensitivity since most kits use only small amounts of feces (<1 g). A direct PCR from crude egg preparations was designed for full compatibility with FLOTAC to accurately quantify eggs per gram feces (epg) and determine species composition. Eggs were recovered from the flotation solution and concentrated by sieving. Lysis was achieved by repeated boiling and freezing cycles – only Trichuris eggs required additional mechanic disruption. Egg lysates were directly used as template for PCR with Phusion DNA polymerase which is particularly resistant to PCR inhibitors. Qualitative results were obtained with feces of goats, cattle, horses, swine, cats, dogs and mice. The finally established protocol was also compatible with quantitative real-time PCR in the presence of EvaGreen and no PCR inhibition was detectable when extracts were diluted at least fourfold. Sensitivity was comparable to DNA isolation protocols and spiked samples with five epg were reliably detected. For Toxocara cati a detection limit below one epg was demonstrated. It was possible to distinguish T. cati and Toxocara canis using high resolution melt (HRM) analysis, a rapid tool for species identification. In human samples, restriction fragment length polymorphism (RFLP) and HRM analysis were used to discriminate Necator americanus and Ancylostoma duodenale. The method is able to significantly improve molecular diagnosis of gastrointestinal nematodes by increasing speed and sensitivity while decreasing overall costs. For identification of species or resistance alleles, analysis of PCR products with many different post

  13. Evaluation of blood pressure changes using vascular transit time.

    PubMed

    Foo, Jong Yong Abdiel; Lim, Chu Sing; Wang, Ping

    2006-08-01

    Imbalance of the human haemodynamic system can provide a prognosis of syncope, dizziness or hypertension. This can be assessed by monitoring its responses to postural change. Examining variations in blood pressure (BP) is deemed an effective means to identify symptoms of this associated condition. However, conventional methods do not promote prolonged monitoring due to the discomfort caused to patients. Established correlations between BP and pulse wave transmission have shown its usefulness in clinical applications. In this study, photoplethysmography and phonocardiography were used to estimate BP changes via observed variations in delay transmission or vascular transit time (VTT) at the upper limb. Thirty-one healthy adults (21 male) were recruited to perform three test activities, namely the arm held at heart level, fully raised up and held down. Association of the three BP indices and heart rate variations with transit time changes was then computed. The results showed that observed VTT changes were related to systolic BP (R(2) = 0.820; p < 0.05), diastolic BP (R(2) = 0.517; p < 0.05), mean arterial pressure (R(2) = 0.673; p < 0.05) and heart rate (R(2) = 0.000; p > 0.05). As systolic BP had the strongest correlation, a regression equation was formulated to associate the two parameters. The non-invasive measuring nature of VTT can be more accommodating to patients, especially during continual monitoring. Moreover, it has the added advantage that the pre-ejection period is not included in its time-related derivations.

  14. Transit times of baseflow in New Zealand rivers

    NASA Astrophysics Data System (ADS)

    Morgenstern, Uwe; Stewart, Mike; Daughney, Chris; Townsend, Dougal

    2015-04-01

    Water quantity and quality responses of catchments to climate and land-use changes are difficult to understand and predict due to complexities of subsurface water flow paths and potentially large groundwater stores. It is difficult to relate the hydrologic responses of catchments to measurable catchment properties. Tritium is ideally suited to provide a measurable parameter of hydrologic response. Tritium, a component of meteoric water, decays with a half-life of 12.32 years after the water enters the groundwater system, and can therefore provide information on transit time of water through the groundwater system over the time range 0 to 200 years mean residence time (MRT). Transit time of the water discharge is one of the most crucial parameters for understanding the response of catchments. In recent years it has become possible to use tritium in a straightforward way for dating of stream and river water due to the decay of the bomb-tritium from atmospheric thermo-nuclear weapons testing, and to improved measurement accuracy for the extremely low natural tritium concentrations. Tritium dating of river water during baseflow conditions from over 120 sites throughout New Zealand show consistent patterns and a good correlation between geology and residence times of the water discharges. Basement rock catchments (greywacke, schist) have very young water of MRT less than 1year, sand-, mud-, limestone catchments have moderately old water of MRT 3-15 years, and porous ignimbrite catchments have very old water of MRT greater than 100 years. For example, the tritium data indicate MRT of 6 - 7 years in the Whanganui River, 3 - 3.5 years in the Rangitikei River, and 9 - 11 years in the large discharges from the Tertiary sediments in the Manawatu catchment. The discharges from the greywacke Ruahine and Tararua Ranges contain very young water with MRT of 0 - 2 years. Associated groundwater stores for the Rangitikei, Manawatu, and Whanganui Rivers are 1, 2, and 5 x 109 m3 of

  15. ASSOCIATION OF BILE ACID RECEPTOR TGR5 VARIATION AND TRANSIT IN HEALTH AND LOWER FUNCTIONAL GASTROINTESTINAL DISORDERS

    PubMed Central

    Camilleri, Michael; Vazquez-Roque, Maria I.; Carlson, Paula; Burton, Duane; Wong, Banny S.; Zinsmeister, Alan R.

    2011-01-01

    Background The membrane bound bile acid (BA) receptor, TGR5, is located on myenteric, cholinergic and nitrergic neurons in colon and proximal small intestine. Our aim was to assess the association of genetic variation in TGR5 and small bowel (SBT) and colonic transit. Methods In 230 healthy controls and 414 patients with lower functional GI disorders (FGID: irritable bowel syndrome [IBS]-alternators [Alt] 84, IBS-constipation [IBS-C] 157, IBS-diarrhea [IBS-D] 173), we tested the association between TGR5 SNP rs11554825 (minor allele frequency 41%) with symptom phenotype (total cohort) and intermediate phenotype (SBT or colonic transit by radioscintigraphy) which was available in 213 people in this cohort. The association with symptom phenotype was assessed using logistic regression, while the association with colonic filling at 6h [CF6], and colonic transit (geometric center [GC] at 24h) was assessed using ANCOVA, in each instance assuming a dominant genetic model. Key Results There was no significant association with symptom phenotype. We observed a potential association of SNP rs11554825 with overall transit: CF6 (p=0.061) and GC24 (p=0.083). The association of the SNP with CF6 in the IBS-D subgroup (p=0.017) indicated the TC/CC subgroup had an average 50% faster SBT compared to the TT subgroup. In IBS-D patients, GC24 was not significantly associated with rs11554825 (TC/CC vs TT). Conclusions and Inferences Variation in TGR5 may contribute to altered SBT and colonic transit in lower FGID. Further studies are required to characterize the potential role of BA receptor TGR5 in the mechanism and treatment of bowel dysfunction in lower FGID. PMID:21883702

  16. Analytic formulae for transit timing variations of planets

    NASA Astrophysics Data System (ADS)

    Deck, Katherine Michele; Agol, Eric

    2015-12-01

    Gravitational interactions between planets in transiting exoplanetary systems lead to variations in the times of transit (TTVs) that are diagnostic of the planetary masses and the dynamical state of the system. I will present analytic formulae for TTVs which can be applied to planetary systems with nearly circular orbits which are not caught in a mean motion resonance. The formulae relate physical parameters, like masses and orbital elements, to direct TTV observables, including shape, amplitude, and timescales. Importantly, the formulae highlight which components of TTVs break degeneracies to allow for unique measurements of planet masses and eccentricities. Additionally, modeling of TTV data using our analytic formulae can be nearly 4 orders of magnitude faster compared with n-body integration. For a number of Kepler systems with TTVs, I will show that our formulae lead to accurate mass and orbital element measurements without full dynamical analyses involving direct integration of the equations of motion. The analytic formulae may ultimately allow for a homogenous analysis of the TTVs (or lack thereof) of many multi-planet systems.

  17. Time trends in upper gastrointestinal diseases and Helicobacter pylori infection in a multiracial Asian population--a 20-year experience over three time periods.

    PubMed

    Leow, A H-R; Lim, Y-Y; Liew, W-C; Goh, K-L

    2016-04-01

    Marked epidemiological changes in upper gastrointestinal diseases and Helicobacter pylori infection have taken place in the Asian Pacific region. In particular, differences with respect to race in the multiracial Asian population in Malaysia have been important and interesting. A time trend study of upper gastrointestinal disease and H. pylori infection in three time periods: 1989-1990, 1999-2000 and 2009-2010 spanning a period of 20 years was carried out. Consecutive first time gastroscopies carried out on patients attending the University of Malaya Medical Center were studied. Diagnoses and H. pylori infection status were carefully recorded. A steady decline in prevalence of duodenal ulcer (DU) and gastric ulcer (GU) from 21.1% to 9.5% to 5.0% and from 11.9% to 9.4% to 9.9% while an increase in erosive oesophagitis (EO) from 2.0% to 8.4% to 9.5% (chi-square for trend; P < 0.001) for the periods 1989-1990, 1999-200 and 2009-2010 were observed. The overall prevalence of H. pylori had also decreased from 51.7% to 30.3% to 11.1% for the same periods of time. The proportion of H. pylori positive ulcers had also decreased: DU (90.1%-69.8%-28.9%) and GU (86.6-56.8%-18.9%) (P < 0.001). This was observed in Malays, Chinese and Indians but the difference over time was most marked in Malays. There was a steady decline in the proportion of patients with gastric and oesophageal cancers. Peptic ulcers have declined significantly over a 20-year period together with a decline in H. pylori infection. In contrast, a steady increase in erosive oesophagitis was observed. Gastric and oesophageal squamous cell cancers have declined to low levels. © 2016 John Wiley & Sons Ltd.

  18. The helpfulness and timing of transition program education.

    PubMed

    Rush, Kathy L; Adamack, Monica; Janke, Robert; Gordon, Jason; Ghement, Isabella R

    2013-01-01

    The purpose of this study was to examine relationships between transition program education and new graduate nurse transition. Although new graduates preferred hands-on learning, the helpfulness of workshops was associated with better transition. New graduates, many of whom were from the Millennial Generation, liked a variety of educational modalities. Access to support was better for nurse graduates who received education delivered throughout the first year of transition.

  19. Time-Distance Seismology and the Solar Transition Region

    NASA Astrophysics Data System (ADS)

    Hansen, Shelley C.; Cally, Paul S.

    2014-12-01

    Time-Distance `travel time' perturbations (as inferred from wave phase) are calculated relative to the quiet-Sun as a function of wave orientation and field inclination in a uniform inclined magnetic field. Modelling indicates that the chromosphere-corona Transition Region (TR) profoundly alters travel times at inclinations from the vertical θ for which the ramp-reduced acoustic cutoff frequency ω c cos θ is similar to the wave frequency ω. At smaller inclinations phase shifts are much smaller as the waves are largely reflected before reaching the TR. At larger inclinations, the shifts resume their quiet-Sun values, although with some resonant oscillatory behaviour. Changing the height of the TR in the model atmosphere has some effect, but the thickness and temperature jump do not change the results substantially. There is a strong correspondence between travel-time shifts and the Alfvén flux that emerges at the top of the modelled region as a result of fast/Alfvén mode conversion. We confirm that the TR transmission coefficient for Alfvén waves generated by mode conversion in the chromosphere is far larger (typically 30 % or more) than for Alfvén waves injected from the photosphere.

  20. Quantum to classical transition induced by gravitational time dilation

    NASA Astrophysics Data System (ADS)

    Sokolov, Boris; Vilja, Iiro; Maniscalco, Sabrina

    2017-07-01

    We study the loss of quantumness caused by time dilation [I. Pikovski, M. Zych, F. Costa, and Č. Brukner, Nat. Phys. 11, 668 (2015), 10.1038/nphys3366] for a Schrödinger cat state. We give a holistic view of the quantum to classical transition by comparing the dynamics of several nonclassicality indicators, such as the Wigner function interference fringe, the negativity of the Wigner function, the nonclassical depth, the Vogel criterion, and the Klyshko criterion. Our results show that only two of these indicators depend critically on the size of the cat, namely, on how macroscopic the superposition is. Finally we compare the gravitation-induced decoherence times to the typical decoherence times due to classical noise originating from the unavoidable statistical fluctuations in the characteristic parameters of the system [J. Trapani, M. Bina, S. Maniscalco, and M. G. A. Paris, Phys. Rev. A 91, 022113 (2015), 10.1103/PhysRevA.91.022113]. We show that the experimental observation of decoherence due to time dilation imposes severe limitations on the allowed levels of classical noise in the experiments.

  1. The Timing of School Transitions and Early Adolescent Problem Behavior

    ERIC Educational Resources Information Center

    Lippold, Melissa A.; Powers, Christopher J.; Syvertsen, Amy K.; Feinberg, Mark E.; Greenberg, Mark T.

    2013-01-01

    This longitudinal study investigates whether rural adolescents who transition to a new school in sixth grade have higher levels of risky behavior than adolescents who transition in seventh grade. Our findings indicate that later school transitions had little effect on problem behavior between sixth and ninth grades. Cross-sectional analyses found…

  2. The Timing of School Transitions and Early Adolescent Problem Behavior

    ERIC Educational Resources Information Center

    Lippold, Melissa A.; Powers, Christopher J.; Syvertsen, Amy K.; Feinberg, Mark E.; Greenberg, Mark T.

    2013-01-01

    This longitudinal study investigates whether rural adolescents who transition to a new school in sixth grade have higher levels of risky behavior than adolescents who transition in seventh grade. Our findings indicate that later school transitions had little effect on problem behavior between sixth and ninth grades. Cross-sectional analyses found…

  3. Detecting nonstationarity and state transitions in a time series

    NASA Astrophysics Data System (ADS)

    Gao, J. B.

    2001-06-01

    One cause of complexity in a time series may be due to nonstationarity and transience. In this paper, we analyze the nonstationarity and transience in a number of dynamical systems. We find that the nonstationarity in the metastable chaotic Lorenz system is due to nonrecurrence. The latter determines a lack of fractal structure in the signal. In 1/fα noise, we find that the associated correlation dimension are local graph dimensions calculated from sojourn points. We also design a transient Lorenz system with a slowly oscillating controlling parameter, and a transient Rossler system with a slowly linearly increasing parameter, with parameter ranges covering a sequence of chaotic dynamics with increased phase incoherence. State transitions, from periodic to chaotic, and vice versa, are identified, together with different facets of nonstationarity in each phase.

  4. Toward a Smartphone Application for Estimation of Pulse Transit Time.

    PubMed

    Liu, He; Ivanov, Kamen; Wang, Yadong; Wang, Lei

    2015-10-27

    Pulse transit time (PTT) is an important physiological parameter that directly correlates with the elasticity and compliance of vascular walls and variations in blood pressure. This paper presents a PTT estimation method based on photoplethysmographic imaging (PPGi). The method utilizes two opposing cameras for simultaneous acquisition of PPGi waveform signals from the index fingertip and the forehead temple. An algorithm for the detection of maxima and minima in PPGi signals was developed, which includes technology for interpolation of the real positions of these points. We compared our PTT measurements with those obtained from the current methodological standards. Statistical results indicate that the PTT measured by our proposed method exhibits a good correlation with the established method. The proposed method is especially suitable for implementation in dual-camera-smartphones, which could facilitate PTT measurement among populations affected by cardiac complications.

  5. Toward a Smartphone Application for Estimation of Pulse Transit Time

    PubMed Central

    Liu, He; Ivanov, Kamen; Wang, Yadong; Wang, Lei

    2015-01-01

    Pulse transit time (PTT) is an important physiological parameter that directly correlates with the elasticity and compliance of vascular walls and variations in blood pressure. This paper presents a PTT estimation method based on photoplethysmographic imaging (PPGi). The method utilizes two opposing cameras for simultaneous acquisition of PPGi waveform signals from the index fingertip and the forehead temple. An algorithm for the detection of maxima and minima in PPGi signals was developed, which includes technology for interpolation of the real positions of these points. We compared our PTT measurements with those obtained from the current methodological standards. Statistical results indicate that the PTT measured by our proposed method exhibits a good correlation with the established method. The proposed method is especially suitable for implementation in dual-camera-smartphones, which could facilitate PTT measurement among populations affected by cardiac complications. PMID:26516861

  6. Factors influencing stream baseflow transit times in tropical montane watersheds

    NASA Astrophysics Data System (ADS)

    Muñoz-Villers, Lyssette E.; Geissert, Daniel R.; Holwerda, Friso; McDonnell, Jeffrey J.

    2016-04-01

    Stream water mean transit time (MTT) is a fundamental hydrologic parameter that integrates the distribution of sources, flow paths, and storages present in catchments. However, in the tropics little MTT work has been carried out, despite its usefulness for providing important information on watershed functioning at different spatial scales in (largely) ungauged basins. In particular, very few studies have quantified stream MTTs or have related these to catchment characteristics in tropical montane regions. Here we examined topographic, land use/cover and soil hydraulic controls on baseflow transit times for nested catchments (0.1-34 km2) within a humid mountainous region, underlain by volcanic soil (Andisols) in central Veracruz (eastern Mexico). We used a 2-year record of bi-weekly isotopic composition of precipitation and stream baseflow data to estimate MTT. Land use/cover and topographic parameters (catchment area and form, drainage density, slope gradient and length) were derived from geographic information system (GIS) analysis. Soil water retention characteristics, and depth and permeability of the soil-bedrock interface were obtained from intensive field measurements and laboratory analysis. Results showed that baseflow MTTs ranged between 1.2 and 2.7 years across the 12 study catchments. Overall, MTTs across scales were mainly controlled by catchment slope and the permeability observed at the soil-bedrock interface. In association with topography, catchment form and the depth to the soil-bedrock interface were also identified as important features influencing baseflow MTTs. The greatest differences in MTTs were found both within groups of small (0.1-1.5 km2) and large (14-34 km2) catchments. Interestingly, the longest stream MTTs were found in the headwater cloud forest catchments.

  7. Acute Appendicitis as Complication of Colon Transit Time Study; A Case Report

    PubMed Central

    Ghahramani, Leila; Roshanravan, Reza; Khodaei, Shahin; Rahimi Kazerooni, Salar; Moslemi, Sam

    2015-01-01

    Colon transit time study with radio opaque markers is a simple method for assessment of colon motility disorder in patients with chronic idiopathic constipation. We report a case of acute appendicitis that was induced by impaction of radio opaque markers after colon transit time study. We think that this case report is first significant complication of colon transit time study until now PMID:26396723

  8. Effect of electrical forepaw stimulation on capillary transit-time heterogeneity (CTH).

    PubMed

    Gutiérrez-Jiménez, Eugenio; Cai, Changsi; Mikkelsen, Irene Klærke; Rasmussen, Peter Mondrup; Angleys, Hugo; Merrild, Mads; Mouridsen, Kim; Jespersen, Sune Nørhøj; Lee, Jonghwan; Iversen, Nina Kerting; Sakadzic, Sava; Østergaard, Leif

    2016-12-01

    Functional hyperemia reduces oxygen extraction efficacy unless counteracted by a reduction of capillary transit-time heterogeneity of blood. We adapted a bolus tracking approach to capillary transit-time heterogeneity estimation for two-photon microscopy and then quantified changes in plasma mean transit time and capillary transit-time heterogeneity during forepaw stimulation in anesthetized mice (C57BL/6NTac). In addition, we analyzed transit time coefficient of variance = capillary transit-time heterogeneity/mean transit time, which we expect to remain constant in passive, compliant microvascular networks. Electrical forepaw stimulation reduced, both mean transit time (11.3% ± 1.3%) and capillary transit-time heterogeneity (24.1% ± 3.3%), consistent with earlier literature and model predictions. We observed a coefficient of variance reduction (14.3% ± 3.5%) during functional activation, especially for the arteriolar-to-venular passage. Such coefficient of variance reduction during functional activation suggests homogenization of capillary flows beyond that expected as a passive response to increased blood flow by other stimuli. This finding is consistent with an active neurocapillary coupling mechanism, for example via pericyte dilation. Mean transit time and capillary transit-time heterogeneity reductions were consistent with the relative change inferred from capillary hemodynamics (cell velocity and flux). Our findings support the important role of capillary transit-time heterogeneity in flow-metabolism coupling during functional activation.

  9. Remotely detected differential pulse transit time as a stress indicator

    NASA Astrophysics Data System (ADS)

    Kaur, Balvinder; Tarbox, Elizabeth; Cissel, Marty; Moses, Sophia; Luthra, Megha; Vaidya, Misha; Tran, Nhien; Ikonomidou, Vasiliki N.

    2015-05-01

    The human cardiovascular system, controlled by the autonomic nervous system (ANS), is one of the first sites where one can see the "fight-or-flight" response due to the presence of external stressors. In this paper, we investigate the possibility of detecting mental stress using a novel measure that can be measured in a contactless manner: Pulse transit time (dPTT), which refers to the time that is required for the blood wave (BW) to cover the distance from the heart to a defined remote location in the body. Loosely related to blood pressure, PTT is a measure of blood velocity, and is also implicated in the "fight-or-flight" response. We define the differential PTT (dPTT) as the difference in PTT between two remote areas of the body, such as the forehead and the palm. Expanding our previous work on remote BW detection from visible spectrum videos, we built a system that remotely measures dPTT. Human subject data were collected under an IRB approved protocol from 15 subjects both under normal and stress states and are used to initially establish the potential use of remote dPPT detection as a stress indicator.

  10. Review article: olestra and its gastrointestinal safety.

    PubMed

    Thomson, A B; Hunt, R H; Zorich, N L

    1998-12-01

    Olestra is a fat substitute made from sucrose and vegetable oil. Olestra is neither digested nor absorbed, and therefore adds no calories or fat to the diet. Because the gut is the only organ that is exposed to olestra, the potential for olestra to affect gastrointestinal structure and function, and the absorption of nutrients from the gut, has been investigated. Histological evaluations performed after long-term feeding studies have shown no indications that olestra causes injury to the gastrointestinal mucosa. Olestra is not metabolized by the colonic microflora, and has no meaningful effects on the metabolic function of these organisms. Studies of gastrointestinal transit have shown that the consumption of olestra with food does not affect gastric emptying, or small or large bowel transit times. Olestra does not affect the absorption of macronutrients, water-soluble vitamins or minerals. It causes a dose-responsive decrease in the availability of the fat-soluble vitamins A, D, E and K; however, this potentially adverse effect is offset by the addition of vitamins to olestra-containing foods. Olestra has no consistent effect on the amount of total bile acids excreted in the faeces, and therefore probably has no significant effect on bile acid absorption. The occurrence of gastrointestinal symptoms, including diarrhoea, loose stools, gas and abdominal cramping, after consumption of olestra under ordinary snacking conditions is comparable to that following consumption of triglyceride-containing snacks.

  11. MOST Space-based Photometry of the Transiting Exoplanet System HD 209458: Transit Timing to Search for Additional Planets

    NASA Astrophysics Data System (ADS)

    Miller-Ricci, Eliza; Rowe, Jason F.; Sasselov, Dimitar; Matthews, Jaymie M.; Guenther, David B.; Kuschnig, Rainer; Moffat, Anthony F. J.; Rucinski, Slavek M.; Walker, Gordon A. H.; Weiss, Werner W.

    2008-07-01

    We report on the measurement of transit times for the HD 209458 planetary system from photometry obtained with the MOST (Microvariability and Oscillations of Stars) space telescope. Deviations from a constant orbital period can indicate the presence of additional planets in the system that are yet undetected, potentially with masses approaching an Earth mass. The MOST data sets of HD 209458 from 2004 and 2005 represent unprecedented time coverage with nearly continuous observations spanning 14 and 43 days and monitoring three transits and 12 consecutive transits, respectively. The transit times that we obtain show no variations on three scales: (1) no long-term change in P since before 2004 at 25 ms level, (2) no trend in transit timings during the 2005 run, and (3) no individual transit timing deviations above 80 s level. Together with previously published transit times from Agol & Steffen, this allows us to place limits on the presence of additional close-in planets in the system, in some cases down to below an Earth mass. This result, along with previous radial velocity work, now eliminates the possibility that a perturbing planet could be responsible for the additional heat source needed to explain HD 209458b's anomalous low density.

  12. Transition Between the Timed up and Go Turn to Sit Subtasks: Is Timing Everything?

    PubMed

    Weiss, Aner; Mirelman, Anat; Giladi, Nir; Barnes, Lisa L; Bennett, David A; Buchman, Aron S; Hausdorff, Jeffrey M

    2016-09-01

    The Timed Up and Go (TUG), one of the most widely used tests of mobility, has been validated and associated with adverse outcomes in the community, acute care, and nursing home setting. It is composed of several distinct subtasks; however, the temporal relationship when transitioning between subtasks has not been well-studied. We tested the hypothesis that longer transition durations between the final turn to the sitting subtasks are associated with worse motor and cognitive performance in older adults. A total of 1055 participants (80.33 ± 7.57 years, 76.96% female) performed the TUG while wearing a 3-dimensional inertial sensor on their lower back. We employed a series of linear regressions to examine the association of the duration between the turn and sitting subtasks with clinical characteristics including motor and cognitive functions. Participants employed 2 different strategies when they transitioned from turning to sitting. (1) Distinct transition strategy: 816 participants (77.34%) first completed the turn before starting to sit. The average duration between these distinct subtasks (D-interval) was 715 ± 980 ms. (2) Overlapping transition strategy: 239 participants (22.65%) started to sit before completing the turn. The average overlap duration between these tasks (O-interval) was 237 ± 269 ms. Participants who employed the distinct transition strategy were slightly younger than those who employed the overlapping transition strategy (P ≤ .013). Higher D-intervals and O-intervals were associated with worse TUG performance (P ≤ .02), with poorer motor and cognitive function, [ie, worse parkinsonian gait (P ≤ .001), lower level of perceptual speed (P ≤ .03), and with worse mobility disability (P ≤ .001)]. A longer D-interval was associated with worse gait speed and bradykinesia (P ≤ .001), whereas a longer O-interval was associated with increased rigidity (P = .004). Older adults apparently employ 2 different strategies

  13. A Transit Timing Posterior Distribution Catalog for all Kepler Planet Candidates

    NASA Astrophysics Data System (ADS)

    Montet, Benjamin; Becker, Juliette; Johnson, John

    2015-01-01

    Thanks to the unprecedented precision of Kepler, the first unambiguous observations of transit timing variations (TTVs) are now in hand. TTVs have afforded us the ability to precisely characterize both transiting and non-transiting exoplanets by observing dynamical interactions in multi-transiting systems. Catalogs attempting to publish transit times of large numbers of Kepler systems exist. However, these catalogs are incomplete: for each event only a point estimate and assumed Gaussian uncertainity of the transit time is included. Moreover, published catalogs only include long-cadence data, do not cover the full Kepler observing baseline, and assume the Kepler noise is perfectly uncorrelated. Here, we present a complete TTV catalog, in which we produce full posterior distributions on the time of each transit for every Kepler planet candidate without any assumptions of Gaussianity in the transit times.

  14. Effects of adlay, buckwheat, and barley on transit time and the antioxidative system in obesity induced rats

    PubMed Central

    Kim, Jung Yun; Son, Bo Kyung

    2012-01-01

    In the present study, we examined whether four grains including adlay (AD), buckwheat (BW), glutinous barley (GB), and white rice (WR) affect the duration of food residence in the gastrointestinal tract and hepatic enzyme activities in rats fed different combinations of the grains. The rats were raised for 4 weeks on a high fat diet based on the American Institute of Nutrition-93 (AIN-93G) diets containing 1% cholesterol and 20% dietary lipids. Forty male rats were divided into four groups and raised for 4 weeks with a diet containing one of the grains. Corresponding to the dietary fiber contents of the experimental grains, gut transit time was shortest in the rats fed GB and increased in the order of BW, AD, and WR. In addition, the accumulated shortest transit time occurred in the GB group. Gut transit time affected weight gain and major organ weight, as it was closely related to the absorption of nutrients. The level of thiobarbituric acid reactive substance (TBARS) in liver was higher in rats fed WR, AD, BW, and GB, indicating that the other grains decreased oxidative stress in vivo more than WR. Glutathione, glutathione peroxidase, and glutathione S-transferase levels in the AD, BW, and GB groups were significantly higher than those in the WR group. In conclusion, reduced colonic transit time has been implicated in reducing the incidence of colon cancer, as evidenced by populations consuming diets rich in fiber. Whole grains such as AD, BW, and GB may contribute to a significant supply of antioxidants to prevent oxidative stress if they are consumed in large amounts. PMID:22808344

  15. Effects of adlay, buckwheat, and barley on transit time and the antioxidative system in obesity induced rats.

    PubMed

    Kim, Jung Yun; Son, Bo Kyung; Lee, Sang Sun

    2012-06-01

    In the present study, we examined whether four grains including adlay (AD), buckwheat (BW), glutinous barley (GB), and white rice (WR) affect the duration of food residence in the gastrointestinal tract and hepatic enzyme activities in rats fed different combinations of the grains. The rats were raised for 4 weeks on a high fat diet based on the American Institute of Nutrition-93 (AIN-93G) diets containing 1% cholesterol and 20% dietary lipids. Forty male rats were divided into four groups and raised for 4 weeks with a diet containing one of the grains. Corresponding to the dietary fiber contents of the experimental grains, gut transit time was shortest in the rats fed GB and increased in the order of BW, AD, and WR. In addition, the accumulated shortest transit time occurred in the GB group. Gut transit time affected weight gain and major organ weight, as it was closely related to the absorption of nutrients. The level of thiobarbituric acid reactive substance (TBARS) in liver was higher in rats fed WR, AD, BW, and GB, indicating that the other grains decreased oxidative stress in vivo more than WR. Glutathione, glutathione peroxidase, and glutathione S-transferase levels in the AD, BW, and GB groups were significantly higher than those in the WR group. In conclusion, reduced colonic transit time has been implicated in reducing the incidence of colon cancer, as evidenced by populations consuming diets rich in fiber. Whole grains such as AD, BW, and GB may contribute to a significant supply of antioxidants to prevent oxidative stress if they are consumed in large amounts.

  16. Refined Assessment of Associations between Drinking Water Residence Time and Emergency Department Visits for Gastrointestinal Illness in Metro Atlanta, Georgia

    PubMed Central

    Levy, Karen; Klein, Mitchell; Sarnat, Stefanie Ebelt; Panwhar, Samina; Huttinger, Alexandra; Tolbert, Paige; Moe, Christine

    2017-01-01

    Recent outbreak investigations suggest that a substantial proportion of waterborne disease outbreaks are attributable to water distribution system issues. In this analysis, we examine the relationship between modeled water residence time (WRT), a proxy for probability of microorganism intrusion into the distribution system, and emergency department visits for gastrointestinal (GI) illness for two water utilities in Metro Atlanta, USA during 1993–2004. We also examine the association between proximity to the nearest distribution system node, based on patients' residential address, and GI illness using logistic regression models. Comparing long (≥90th percentile) to intermediate WRTs (11th to 89th percentile), we observed a modestly increased risk for GI illness for Utility 1 (OR=1.07, 95% CI: 1.02–1.13), which had substantially higher average WRT than Utility 2, for which we found no increased risk (OR=0.98, 95% CI: 0.94–1.02). Examining finer, 12-hour increments of WRT, we found that exposures >48 hrs were associated with increased risk of GI illness, and exposures of >96 hrs had the strongest associations, although none of these associations were statistically significant. Our results suggest that utilities might consider reducing WRTs to <2–3 days or add booster disinfection in areas with longer WRT, to minimize risk of GI illness from water consumption. PMID:27441862

  17. Refined assessment of associations between drinking water residence time and emergency department visits for gastrointestinal illness in Metro Atlanta, Georgia.

    PubMed

    Levy, Karen; Klein, Mitchel; Sarnat, Stefanie Ebelt; Panwhar, Samina; Huttinger, Alexandra; Tolbert, Paige; Moe, Christine

    2016-08-01

    Recent outbreak investigations suggest that a substantial proportion of waterborne disease outbreaks are attributable to water distribution system issues. In this analysis, we examine the relationship between modeled water residence time (WRT), a proxy for probability of microorganism intrusion into the distribution system, and emergency department visits for gastrointestinal (GI) illness for two water utilities in Metro Atlanta, USA during 1993-2004. We also examine the association between proximity to the nearest distribution system node, based on patients' residential address, and GI illness using logistic regression models. Comparing long (≥90th percentile) with intermediate WRTs (11th to 89th percentile), we observed a modestly increased risk for GI illness for Utility 1 (OR = 1.07, 95% CI: 1.02-1.13), which had substantially higher average WRT than Utility 2, for which we found no increased risk (OR = 0.98, 95% CI: 0.94-1.02). Examining finer, 12-hour increments of WRT, we found that exposures >48 h were associated with increased risk of GI illness, and exposures of >96 h had the strongest associations, although none of these associations was statistically significant. Our results suggest that utilities might consider reducing WRTs to <2-3 days or adding booster disinfection in areas with longer WRT, to minimize risk of GI illness from water consumption.

  18. Adaptation status and related factors at 2 time points after surgery in patients with gastrointestinal tract cancer.

    PubMed

    Mizuno, Michiyo; Asano, Yoshihiro; Sumi, Tomomi; Inoue, Yumiko

    2011-01-01

    The diagnosis of cancer and subsequent surgery represent a life-threatening and stressful experience with several factors relating to the patient's process of adaptation. The purpose of this longitudinal study was to examine adaptation status and related factors in patients who have been diagnosed with and undergone surgery for gastrointestinal tract cancer. The survey was administered twice (2 weeks after discharge from the hospital and 6 months after surgery). Twenty-five patients responded to both questionnaires about quality of life (QOL), which was regarded as an index of adaptation status, and illness-related demands, the "why me?" question, sense of coherence (SOC), perceived social support, and disease data. On the second survey, scores about illness-related demands, the "why me?" question, SOC, and QOL, other than the QOL social relationships domain, improved, but scores about perceived social support decreased. A correlation between the "why me?" question and the SOC and the difference in the overall QOL by cancer site were found only on the second survey. Low demands of illness and high SOC predicted high QOL on both surveys. Except for social relationships, adaptation status 6 months after surgery improved compared with after discharge. The relationships between some variables took on a significant meaning at 6 months after surgery. Comparisons between 2 time points suggested that most cancer patients had dispositional resilience. Meanwhile, the findings related to social relationships and the relationships between some variables suggested the necessity for professional interventions targeting these factors.

  19. Timing or Dosing of Intravenous Proton Pump Inhibitors in Acute Upper Gastrointestinal Bleeding Has Low Impact on Costs.

    PubMed

    Lu, Yidan; Adam, Viviane; Teich, Vanessa; Barkun, Alan

    2016-10-01

    High-dose intravenous proton pump inhibitors (PPIs) post endoscopy are recommended in non-variceal upper gastrointestinal bleeding (UGIB), as they improve outcomes of patients with high-risk lesions. Determine the budget impact of using different PPI regimens in treating non-variceal UGIB, including pre- and post-endoscopic use, continuous infusion (high dose), and intermittent bolus (twice daily) dosing. A budget impact analysis using a decision model informed with data from the literature adopting a US third party payer's perspective with a 30-day time horizon was used to determine the total cost per patient (US$2014) presenting with acute UGIB. The base-case employing high-dose pre- and post-endoscopic IV PPI was compared with using only post-endoscopic PPI. For each, continuous or intermittent dosing regimens were assessed with associated incremental costs. Deterministic and probabilistic sensitivity analyses were performed. The overall cost per patient is $11,399 when high-dose IV PPIs are initiated before endoscopy. The incremental costs are all inferior in alternate-case scenarios: $106 less if only post-endoscopic high-dose IVs are used; with intermittent IV bolus dosing, the savings are $223 if used both pre and post endoscopy and $191 if only administered post endoscopy. Subgroup analysis suggests cost savings in patients with clean-base ulcers who are discharged early after endoscopy. Results are robust to sensitivity analysis. The incremental costs of using different IV PPI regimens are modest compared with total per patient costs.

  20. Semi-automatic detection of Gd-DTPA-saline filled capsules for colonic transit time assessment in MRI

    NASA Astrophysics Data System (ADS)

    Harrer, Christian; Kirchhoff, Sonja; Keil, Andreas; Kirchhoff, Chlodwig; Mussack, Thomas; Lienemann, Andreas; Reiser, Maximilian; Navab, Nassir

    2008-03-01

    Functional gastrointestinal disorders result in a significant number of consultations in primary care facilities. Chronic constipation and diarrhea are regarded as two of the most common diseases affecting between 2% and 27% of the population in western countries 1-3. Defecatory disorders are most commonly due to dysfunction of the pelvic floor or the anal sphincter. Although an exact differentiation of these pathologies is essential for adequate therapy, diagnosis is still only based on a clinical evaluation1. Regarding quantification of constipation only the ingestion of radio-opaque markers or radioactive isotopes and the consecutive assessment of colonic transit time using X-ray or scintigraphy, respectively, has been feasible in clinical settings 4-8. However, these approaches have several drawbacks such as involving rather inconvenient, time consuming examinations and exposing the patient to ionizing radiation. Therefore, conventional assessment of colonic transit time has not been widely used. Most recently a new technique for the assessment of colonic transit time using MRI and MR-contrast media filled capsules has been introduced 9. However, due to numerous examination dates per patient and corresponding datasets with many images, the evaluation of the image data is relatively time-consuming. The aim of our study was to develop a computer tool to facilitate the detection of the capsules in MRI datasets and thus to shorten the evaluation time. We present a semi-automatic tool which provides an intensity, size 10, and shape-based 11,12 detection of ingested Gd-DTPA-saline filled capsules. After an automatic pre-classification, radiologists may easily correct the results using the application-specific user interface, therefore decreasing the evaluation time significantly.

  1. Deconfinement phase transition in an expanding quark system in the relaxation time approximation

    NASA Astrophysics Data System (ADS)

    Yang, Zhenwei; Zhuang, Pengfei

    2004-03-01

    We investigated the effects of nonequilibrium and collision terms on the deconfinement phase transition of an expanding quark system in Friedberg-Lee model in relaxation time approximation. By calculating the effective quark potential, the critical temperature of the phase transition is dominated by the mean field, while the collisions among quarks and mesons change the time structure of the phase transition significantly.

  2. Methyl-orvinol-Dual activity opioid receptor ligand inhibits gastrointestinal transit and alleviates abdominal pain in the mouse models mimicking diarrhea-predominant irritable bowel syndrome.

    PubMed

    Zielińska, Marta; Jarmuż, Agata; Wasilewski, Andrzej; Cami-Kobeci, Gerta; Husbands, Stephen; Fichna, Jakub

    2017-04-01

    Diarrhea-predominant irritable bowel syndrome (IBS-D) is a functional disorder of the gastrointestinal (GI) tract. The major IBS-D symptoms include diarrhea, abdominal pain and discomfort. High density of opioid receptors (ORs) in the GI tract and their participation in the maintenance of GI homeostasis make ORs ligands an attractive option for developing new anti-IBS-D treatments. The aim of this study was to characterize the effect of methyl-orvinol on the GI motility and secretion and in mouse models mimicking symptoms of IBS-D. In vitro, the effects of methyl-orvinol on electrical field stimulated smooth muscle contractility and epithelial ion transport were characterized in the mouse colon. In vivo, the following tests were used to determine methyl-orvinol effect on mouse GI motility: colonic bead expulsion, whole GI transit and fecal pellet output. An antinociceptive action of methyl-orvinol was assessed in the mouse model of visceral pain induced by mustard oil. Methyl-orvinol (10(-10) to 10(-6)M) inhibited colonic smooth muscle contractions in a concentration-dependent manner. This effect was reversed by naloxone (non-selective opioid antagonist) and β-funaltrexamine (selective MOP antagonist). Experiments with a selective KOP receptor agonist, U50488 revealed that methyl-orvinol is a KOP receptor antagonist in the GI tract. Methyl-orvinol enhanced epithelial ion transport. In vivo, methyl-orvinol inhibited colonic bead expulsion and prolonged GI transit. Methyl-orvinol improved hypermotility and reduced abdominal pain in the mouse models mimicking IBS-D symptoms. Methyl-orvinol could become a promising drug candidate in chronic therapy of functional GI diseases such as IBS-D. Copyright © 2016 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  3. Conductivity and transit time estimates of a soil liner

    USGS Publications Warehouse

    Krapac, I.G.; Cartwright, K.; Panno, S.V.; Hensel, B.R.; Rehfeldt, K.H.; Herzog, B.L.

    1990-01-01

    A field-scale soil linear was built to assess the feasibilty of constructing a liner to meet the saturated hydraulic conductivity requirement of the U.S. EPA (i.e., less than 1 ?? 10-7 cm/s), and to determine the breakthrough and transit times of water and tracers through the liner. The liner, 8 ?? 15 ?? 0.9 m, was constructed in 15-cm compacted lifts using a 20,037-kg pad-foot compactor and standard engineering practices. Estimated saturated hydraulic conductivities were 2.4 ?? 10-9 cm/s, based on data from large-ring infiltrometers; 4.0 ?? 10-8 cm/s from small-ring infiltrometers; and 5.0 ?? 10-8 cm/s from a water-balance analysis. These estimates were derived from 1 year of monitoring water infiltration into the linear. Breakthrough of tracers at the base of the liner was estimated to be between 2 and 13 years, depending on the method of calculation and the assumptions used in the calculation.

  4. Pulse transit time and heart rate variability in sleep staging.

    PubMed

    Shahrbabaki, Sobhan Salari; Ahmed, Beena; Penzel, Thomas; Cvetkovic, Dean

    2016-08-01

    This paper presents a new and robust algorithm for detection of sleep stages by using the lead I of the Electrocardiography (ECG) and a fingertip Photoplethysmography (PPG) sensor, validated using multiple overnight PSG recordings consisting of 20 human subjects (9 insomniac and 11 healthy). Heart Rate Variability (HRV) and Pulse Transit Time (PTT) biomarkers which were extracted from ECG and PPG biosignals then employed to extract features. Distance Weighted k-Nearest Neighbours (DWk-NN) was used as classifier to differentiate sleep epochs. The validation of the algorithm was evaluated by Leave-One-Out-Cross-Validation method. The average accuracy of 73.4% with standard deviation of 6.4 was achieved while the algorithm could distinguish stages 2, 3 of non-rapid eye movement sleep by average sensitivity of almost 80%. The lowest mean sensitivity of 53% was for stage 1. These results demonstrate that an algorithm based on PTT and HRV spectral analysis is able to classify and distinguish sleep stages with high accuracy and sensitivity. In addition the proposed algorithm is capable to be improved and implemented as a wearable, comfortable and cheap instrument for sleep screening.

  5. Constipation and colonic transit times in children with morbid obesity.

    PubMed

    vd Baan-Slootweg, Olga H; Liem, Olivia; Bekkali, Noor; van Aalderen, Wim M C; Rijcken, Tammo H Pels; Di Lorenzo, Carlo; Benninga, Marc A

    2011-04-01

    The aim of the study was to determine the frequency of functional constipation according to the Rome III criteria in children with morbid obesity and to evaluate by measuring colonic transit times (CTTs) whether decreased colonic motility is present in these children. Ninety-one children with morbid obesity ages 8 to 18 years, entering a prospective, randomized controlled study evaluating the effect of an outpatient versus inpatient treatment program of obesity, participated. All of the children filled out a standardized questionnaire regarding their bowel habits, and CTTs were measured using radioopaque markers. Food diaries were also recorded to evaluate their diet. A total of 19 children (21%) had functional constipation according to the Rome III criteria, whereas 1 child had functional nonretentive fecal incontinence. Total CTT exceeded 62 hours in only 10.5% of the children with constipation, and among them, 2 had a total CTT of >100 hours. In the nonconstipated group 8.3% had a delayed CTT. Furthermore, no difference was found between the diet of children with or without constipation, specifically not with respect to fiber and fat intake. Our study confirms a high frequency of functional constipation in children with obesity, using the Rome III criteria. However, abnormal colonic motility, as measured by CTT, was delayed in only a minority of patients. No relation was found between constipation in these children and fiber or fat intake.

  6. Transit time kinetics in ordered and disordered vascular trees.

    PubMed

    Karshafian, Raffi; Burns, Peter N; Henkelman, Mark R

    2003-10-07

    Imaging modalities exploit tracer-dilution methods to measure bulk haemodynamic parameters such as blood flow and volume at the level of the microcirculation. Here, we ask the question of whether the kinetics of a tracer can reveal morphological information about the vessels through which the tracers flow. The goal is to relate the acquired time-intensity characteristic to details of the vascular structure that lies below the imaging resolution. Two fractal vascular models are developed that represent organized 'kidney-like' and disorganized 'tumour-like' structures. The models are generated using simple rules of branching and fractal geometry in two dimensions. Blood flow and tracer kinetics are simulated using fundamental laws of haemodynamics. The flow conditions are matched in the two models. The fractal box dimensions of the kidney (D(B) = 1.67 +/- 0.01) and the tumour (D(B) = 1.80 +/- 0.01) vasculatures fall in the range given in the literature (D(B) = 1.61 +/- 0.06 and D(B) = 1.84 +/- 0.04, respectively). The tracer kinetic curves of the kidney and the tumour vasculatures have the same initial slope and final asymptote, corresponding to the same flow rate and vascular volume, but have different forms. The difference in the two curves is related to the distribution function of transit times of the vascular models, and is a consequence of the randomness introduced in vessel diameter and length. In principle, the form of the tracer kinetic curve from a contrast imaging study may offer information relating not only to vascular volume and flow rate, but also to the organization of a microvascular network.

  7. Modeling hyporheic exchange and in-stream transport with time-varying transit time distributions

    NASA Astrophysics Data System (ADS)

    Ball, A.; Harman, C. J.; Ward, A. S.

    2014-12-01

    Transit time distributions (TTD) are used to understand in-stream transport and exchange with the hyporheic zone by quantifying the probability of water (and of dissolved material) taking time T to traverse the stream reach control volume. However, many studies using this method assume a TTD that is time-invariant, despite the time-variability of the streamflow. Others assume that storage is 'randomly sampled' or 'well-mixed' with a fixed volume or fixed exchange rate. Here we present a formulation for a time-variable TTD that relaxes both the time-invariant and 'randomly sampled' assumptions and only requires a few parameters. The framework is applied to transient storage, representing some combination of in-stream and hyporheic storage, along a stream reach. This approach does not assume that hyporheic and dead-zone storage is fixed or temporally-invariant, and allows for these stores to be sampled in more physically representative ways determined by the system itself. Instead of using probability distributions of age, probability distributions of storage (ranked by age) called Ω functions are used to describe how the off-stream storage is sampled in the outflow. Here the Ω function approach is used to describe hyporheic exchange during diurnal fluctuations in streamflow in a gaining reach of the H.J. Andrews Experimental Forest. The breakthrough curves of salt slugs injected four hours apart over a 28-hour period show a systematic variation in transit time distribution. This new approach allows us to relate these salt slug TTDs to a corresponding time-variation in the Ω function, which can then be related to changes in in-stream storage and hyporheic zone mobilization under varying flow conditions. Thus, we can gain insights into how channel storage and hyporheic exchange are changing through time without having to specify difficult to measure or unmeasurable quantities of our system, such as total storage.

  8. Effects of Timing, Sex, and Age on Site-Specific Gastrointestinal Permeability Testing in Children and Adults

    PubMed Central

    McOmber, Mark E.; Ou, Ching-Nan; Shulman, Robert J.

    2010-01-01

    Summary Objectives Measurement of gastrointestinal (GI) permeability is used commonly in research and often clinically. Despite its utility, little is known about sugar excretion timeframes or the potential effects of age and gender in GI permeability testing. We sought to determine the timeframes of sugar excretion and the potential effects of age and gender on urinary recovery of the sugars. Methods Healthy adults (n=17) and children (n=15) fasted four hours after the evening meal and then ingested a solution of sucrose, lactulose, mannitol, and sucralose. Urine was collected at 30, 60, and 90 minutes after ingestion and then each time the subjects voided over the next 24 hr. Each urine void was collected separately. Results Median age for the adults was 47.5 yr. (range 21-57 yr.) and for children 10 yr. (5-17). There were no differences between children and adults in mean percent dose of sugar recovered. The time of peak urinary recovery of the sugars was generally similar between children and adults. Sucrose urinary recovery declined with age (P = 0.008; r2 = 0.19) unrelated to gender. Lactulose and sucralose urinary recovery declined with age in females (P = 0.05, r2 = 0.24 and P = 0.011, r2 = 0.41, respectively) but not in males. Conclusions Overall, sugar urinary recovery is comparable in children and adults. Specific sugar urinary recovery may change as a function of age and/or gender. These results need to be taken into account when planning and interpreting GI permeability studies. PMID:20081547

  9. Outcomes following acute nonvariceal upper gastrointestinal bleeding in relation to time to endoscopy: results from a nationwide study.

    PubMed

    Jairath, V; Kahan, B C; Logan, R F A; Hearnshaw, S A; Doré, C J; Travis, S P L; Murphy, M F; Palmer, K R

    2012-08-01

    Despite the established efficacy of therapeutic endoscopy, the optimum timeframe for performing endoscopy in patients with nonvariceal upper gastrointestinal bleeding (NVUGIB) remains unclear. The aim of the current audit study was to examine the relationship between time to endoscopy and clinical outcomes in patients presenting with NVUGIB. This study was a prospective national audit performed in 212 UK hospitals. Regression models examined the relationship between time to endoscopy and mortality, rebleeding, need for surgery, and length of hospital stay. In 4478 patients, earlier endoscopy ( < 12 hours) was not associated with a lower mortality or need for surgery compared with later ( > 24 hours) endoscopy (odds ratio [OR] for mortality 0.98, 95 % confidence interval [CI] 0.88 - 1.09 for endoscopy > 24 hours vs. < 12 hours; P = 0.70). In patients receiving therapeutic endoscopy, there was a nonsignificant trend towards an increase in rebleeding associated with later endoscopy (OR 1.13, 95 %CI 0.97 - 1.32 for endoscopy > 24 hours vs. < 12 hours), with the converse seen in patients not requiring therapeutic endoscopy (OR 0.83, 95 %CI 0.73 - 0.95 for endoscopy > 24 hours vs. < 12 hours; interaction P = 0.003). Later endoscopy ( > 24 hours) was associated with an increase in risk-adjusted length of hospital stay (1.7 days longer, 95 %CI 1.39 - 1.99 vs. < 12 hours; P < 0.001). Earlier endoscopy was not associated with a reduction in mortality or need for surgery. However, it was associated with an increased efficiency of care and potentially improved control of hemorrhage in higher risk patients, supporting the routine use of early endoscopy unless specific contraindications exist. These results may help inform the debate about emergency endoscopy service provision. © Georg Thieme Verlag KG Stuttgart · New York.

  10. Gastrointestinal bleeding.

    PubMed

    Marek, T A

    2011-11-01

    Gastrointestinal bleeding remains one of the most important emergencies in gastroenterology. Despite this, only about 100 abstracts concerning gastrointestinal bleeding (excluding bleeding complicating endoscopic procedures) were presented at this year's Digestive Disease Week (DDW; 7-10 May 2011; Chicago, Illinois, USA), accounting for less than 2% of all presented lectures and posters. It seems that the number of such abstracts has been decreasing over recent years. This may be due in part to the high level of medical care already achieved, especially in the areas of pharmacotherapy and endoscopic treatment of gastrointestinal bleeding. In this review of gastrointestinal bleeding, priority has been given to large epidemiological studies reflecting "real life," and abstracts dealing more or less directly with endoscopic management. © Georg Thieme Verlag KG Stuttgart · New York.

  11. Gastrointestinal manifestations.

    PubMed

    Tanowitz, H B; Simon, D; Weiss, L M; Noyer, C; Coyle, C; Wittner, M

    1996-11-01

    Gastrointestinal disease is a common problem in the setting of HIV-1 infection. As patients live longer and other opportunistic pathogens are suppressed, these problems are becoming even more important in the quality of life.

  12. Time-variant Catchment Transit Time Distribution and StorAge Selection Functions in Neighbouring Catchments

    NASA Astrophysics Data System (ADS)

    Klaus, J.; Rodriguez, N. B.; McGuire, K. J.

    2016-12-01

    The understanding of the catchment functions of storage, mixing, and release is a major research challenge as their behavior is fundamental for understanding water quality and flow quantity and timing. Generally, the complexity of the flow paths and associated mixing processes is still a major hindrance to a thorough understanding of catchment functions. Catchment transit time distributions can be used as an integrative descriptor of catchment functions. Here we aim to understand these fundamental catchment functions in four neighboring catchments of the HJA Experimental Forest in Oregon, USA. The areas of the four catchments (WS2, WS3, WS9, WS10) range from 0.085 to 1.011 km2. The catchments are fully forested with Douglas fir, western hemlock, and western redcedar dominating the lower elevations, and noble fir, Pacific silver fir, Douglas fir dominating higher elevations. Geology is dominated by volcaniclastics, covering 68% to 99% of the catchments. We employed a two storage conceptual model in each catchment for stream flow and transport modeling. We used solutions of the Master Equation to determine transit time distributions. We assumed randomly sampled/fully mixed conditions in each storage to model 18Oxygen in stream flow over a two year period. For example, modeling results for WS10 yielded a Nash-Sutcliffe efficiency (NSE) of 0.84 for stream flow of and a NSE of 0.7 for the (volume weighted) 18O in stream flow. Furthermore, we derived the master transit time distribution (mttd) for the catchments. Eventually we investigated the landscape controls (topography, geology, morphology) on mttd and the dynamics of storage selection functions of each catchment.

  13. Colonic transit time after spinal cord injury: any clinical significance?

    PubMed

    Leduc, Bernard E; Spacek, Elena; Lepage, Yves

    2002-01-01

    Both bowel dysfunction and increases in colonic transit time (CTT) are frequently observed in individuals with spinal cord injury; however, it is unknown whether there is an association between chronic intestinal problems and changes in CTTs. The current study investigates a possible relationship between the main intestinal symptoms of SCI patients and CTT values. The following clinical variables and symptoms were investigated and collected in 30 individuals with SCI: total time for bowel care, abdominal pain, abdominal gas, success of rectal emptying, fecal incontinence, and decrease in quality of life. Total and segmental CTTs (right colon, left colon, and rectosigmoid colon) were assessed using radiopaque markers. The effects of the sociodemographic variables and the clinical symptoms on the different CTTs (total and segmental) were analyzed. The assessed clinical conditions were observed in the following percentages of subjects: abdominal gas symptoms (70%), fecal incontinence (56%), abdominal pain (63%), total time for bowel care > 1 hour (11%), difficult rectal emptying (66%), and decrease in quality of life (36%). We also observed an increase in total CTT in 47% of subjects; increases in segmental CTT were found in the right colon in 23%, in the left colon (60%), and in the rectosigmoid segment (23%). Statistical analyses failed to show a significant difference in mean CTT values between the group of symptomatic patients (1 or more symptoms) and the group of asymptomatic patients. No significant difference could be detected in the incidence of each intestinal symptom between the group of participants with normal CTT values and those with abnormal CTT values. For each of the clinical data assessed separately, a significantly longer CTT (left colon) was associated with the lack of abdominal pain (P < .03) and the presence of fecal incontinence (P < .01); successful rectal emptying was associated with significantly shorter total (P < .02) and segmental CTTs for

  14. Pre-cultivation with Selected Prebiotics Enhances the Survival and the Stress Response of Lactobacillus rhamnosus Strains in Simulated Gastrointestinal Transit.

    PubMed

    Succi, Mariantonietta; Tremonte, Patrizio; Pannella, Gianfranco; Tipaldi, Luca; Cozzolino, Autilia; Romaniello, Rossana; Sorrentino, Elena; Coppola, Raffaele

    2017-01-01

    In our study, we dwelled upon combinations of lactobacilli/prebiotics, considering four different strains belonging to the Lactobacillus rhamnosus species, including Lactobacillus rhamnosus GG (LGG), and different prebiotics often found in commercial synbiotic products, such as inulin, lactulose and polyols mannitol and sorbitol. In the first step of the research, the survival, the growth kinetic parameters and the protein expression of Lb. rhamnosus strains cultivated in presence of the different prebiotics as a unique carbon source were evaluated. In the second step, the influence of pre-cultivation in medium added of metabolizable prebiotics on the strains survival to simulated gastrointestinal (GI) transit, assayed without prebiotics addition, was estimated. Our results showed that the presence in the medium of certain low fermented prebiotics, specific for each strain, represents a stress factor that significantly affects the growth of Lb. rhamnosus strains, inducing the up-regulation of several proteins. In detail, all added prebiotics used as unique carbon source caused a growth retard compared with glucose, as testified by increased values of the lag phase and decreased values of the μmax. Mannitol evidenced intermediate μmax values between those registered with glucose and those detected with the other assayed prebiotics. Moreover, the cultivation with prebiotics induced the over expression of 7 protein bands. Interestingly, we found a correlation between the up-regulation of two specific stress proteins, called P4 (ATP-binding subunit Clpx) and P7 (GrpE), and the death kinetic parameters (resistance and cells viability) registered during the simulated GI transit of strains pre-cultivated with specific, low fermented prebiotics. Specifically, the highest resistance and gastric-vitality scores were highlighted for the strain AT195 when pre-cultivated in presence of sorbitol. Conversely, the lowest values were found in the case of DSM20021 pre

  15. Pre-cultivation with Selected Prebiotics Enhances the Survival and the Stress Response of Lactobacillus rhamnosus Strains in Simulated Gastrointestinal Transit

    PubMed Central

    Succi, Mariantonietta; Tremonte, Patrizio; Pannella, Gianfranco; Tipaldi, Luca; Cozzolino, Autilia; Romaniello, Rossana; Sorrentino, Elena; Coppola, Raffaele

    2017-01-01

    In our study, we dwelled upon combinations of lactobacilli/prebiotics, considering four different strains belonging to the Lactobacillus rhamnosus species, including Lactobacillus rhamnosus GG (LGG), and different prebiotics often found in commercial synbiotic products, such as inulin, lactulose and polyols mannitol and sorbitol. In the first step of the research, the survival, the growth kinetic parameters and the protein expression of Lb. rhamnosus strains cultivated in presence of the different prebiotics as a unique carbon source were evaluated. In the second step, the influence of pre-cultivation in medium added of metabolizable prebiotics on the strains survival to simulated gastrointestinal (GI) transit, assayed without prebiotics addition, was estimated. Our results showed that the presence in the medium of certain low fermented prebiotics, specific for each strain, represents a stress factor that significantly affects the growth of Lb. rhamnosus strains, inducing the up-regulation of several proteins. In detail, all added prebiotics used as unique carbon source caused a growth retard compared with glucose, as testified by increased values of the lag phase and decreased values of the μmax. Mannitol evidenced intermediate μmax values between those registered with glucose and those detected with the other assayed prebiotics. Moreover, the cultivation with prebiotics induced the over expression of 7 protein bands. Interestingly, we found a correlation between the up-regulation of two specific stress proteins, called P4 (ATP-binding subunit Clpx) and P7 (GrpE), and the death kinetic parameters (resistance and cells viability) registered during the simulated GI transit of strains pre-cultivated with specific, low fermented prebiotics. Specifically, the highest resistance and gastric-vitality scores were highlighted for the strain AT195 when pre-cultivated in presence of sorbitol. Conversely, the lowest values were found in the case of DSM20021 pre

  16. Rapid orocecal transit time in obese children measured by hydrogen breath test.

    PubMed

    Rerksuppaphol, Sanguansak; Rerksuppaphol, Lakkana

    2012-12-01

    Gastrointestinal motility may correlate with an unusual nutritional status, such as obesity. The orocecal transit time (OCTT) is one parameter of GI motility. The primary objective of the present study was to compare OCTT in obese and non-obese children; secondary objectives were to assess the correlation between OCTT and body mass index (BMI) or appetite score. A cross-sectional study was conducted in 44 children. Twenty-one obese and 18 non-obese children were included in the final analysis. Demographic data and anthropometric parameters were collected. The breath hydrogen test (BHT) using lactulose was performed to determine OCTT. Appetite score using visual analog scale was measured at the beginning and end of the present study. The difference between these scores was attributed as an increase of appetite. Student t-test and Chi-square test were employed to compare the differences between groups. Pearson's correlation was used to measure the correlation between parameters. Mean OCTT in obese children was significantly faster than in non-obese children (70.0 versus 81.1 min, respectively; p-value = 0.005). The increases of appetite score during study were not significantly different between obese and non-obese children (4.3 vs. 2.9; p-value = 0.19). OCTT was significantly associated with BMI in the inverse manner (r = -0.51; p-value = 0.001), but was not significantly correlated with the appetite score (r = -0.24; p-value = 0.15). OCTT in obese children was faster than in non-obese children. OCTT was moderately inversely correlated with the BMI, and had a trend to negative correlation with the appetite score, though without reaching a significant value.

  17. [Gastrointestinal bleeding].

    PubMed

    Lanas, Ángel

    2015-09-01

    In the Digestive Disease Week in 2015 there have been some new contributions in the field of gastrointestinal bleeding that deserve to be highlighted. Treatment of celecoxib with a proton pump inhibitor is safer than treatment with nonselective NSAID and a proton pump inhibitor in high risk gastrointestinal and cardiovascular patients who mostly also take acetylsalicylic acid. Several studies confirm the need to restart the antiplatelet or anticoagulant therapy at an early stage after a gastrointestinal hemorrhage. The need for urgent endoscopy before 6-12 h after the onset of upper gastrointestinal bleeding episode may be beneficial in patients with hemodynamic instability and high risk for comorbidity. It is confirmed that in Western but not in Japanese populations, gastrointestinal bleeding episodes admitted to hospital during weekend days are associated with a worse prognosis associated with delays in the clinical management of the events. The strategy of a restrictive policy on blood transfusions during an upper GI bleeding event has been challenged. Several studies have shown the benefit of identifying the bleeding vessel in non varicose underlying gastric lesions by Doppler ultrasound which allows direct endoscopic therapy in the patient with upper GI bleeding. Finally, it has been reported that lower gastrointestinal bleeding diverticula band ligation or hemoclipping are both safe and have the same long-term outcomes. Copyright © 2015 Elsevier España, S.L.U. All rights reserved.

  18. Transition between the Timed Up and Go turn to sit subtasks: Is timing everything?

    PubMed Central

    Weiss, Aner; Mirelman, Anat; Giladi, Nir; Barnes, Lisa L.; Bennett, David A.; Buchman, Aron S.; Hausdorff, Jeffrey M.

    2016-01-01

    Objective The Timed Up and Go (TUG), one of the most widely used tests of mobility, has been validated and associated with adverse outcomes in the community, acute care and nursing home setting. It is composed of several distinct subtasks, however, the temporal relationship when transitioning between subtasks has not been well-studied. We tested the hypothesis that longer transition durations between the final turn to the sitting subtasks are associated with worse motor and cognitive performance in older adults. Methods 1,055 participants (80.33±7.57 yrs, 76.96% female) performed the TUG while wearing a 3-D inertial sensor on their lower back. We employed a series of linear regressions to examine the association of the duration between the turn and sitting subtasks with clinical characteristics including motor and cognitive functions. Results Subjects employed two different strategies when they transitioned from turning to sitting: (1) Distinct Transition strategy (DTS): 816 participants (77.34%) first completed the turn before starting to sit. The average duration between these distinct subtasks (D-interval) was 715±980msec. (2) Overlapping Transition strategy (OTS): 239 participants (22.65%) started to sit before completing the turn. The average overlap duration between these tasks (O-interval) was 237±269msec. Participants who employed the DTS were slightly younger than those who employed the OTS (p≤0.013). Higher D-intervals and O-intervals were associated with worse TUG performance (p≤0.02), with poorer motor and cognitive function, i.e. worse parkinsonian gait (p≤0.001), lower level of perceptual speed (p≤0.03), and with worse mobility disability (p≤0.001). A longer D-interval was associated with worse gait speed and bradykinesia (p≤0.001), while a longer O-interval was associated with increased rigidity (p=0.004). Conclusion Older adults apparently employ two different strategies when transitioning from turning to sitting. The instrumented TUG

  19. Defaecography and colonic transit time for the evaluation of female patients with obstructed defaecation.

    PubMed

    Cosentino, Maria; Beati, Claudio; Fornari, Simona; Capalbo, Emanuela; Peli, Michela; Lovisatti, Maria; Cariati, Maurizio; Cornalba, Gianpaolo

    2014-11-01

    Colonic transit time and defaecography are well known, commonly used studies for evaluating patients with chronic constipation. The aim of this study was to compare colonic transit time with radiopaque markers and defaecography in female patients with obstructed defaecation. In a prospective observational study, between January 2010 and December 2012, a total of 30 female patients, mean age 60 years, with symptoms of obstructed defaecation were subjected to colonic transit time and defaecography, and divided into two groups: normal or abnormal colon transit time. The results were statistically compared using the Chi-square test. The comparison of data between colonic transit time and defaecography showed the following groups: group 1 (6/30 = 20 %) with normal colonic transit time but abnormal defaecography, and group 2 (24/30 = 80 %) with abnormal colonic transit time; the latter was further divided into two subgroups: group 2a (4/24 = 17 %), patients with inertia coli; group 2b (20/24 = 83 %), patients with impaired defaecation demonstrated at defaecography. There was a significant statistical difference between the radiological findings in these groups. This study confirmed the value of both defaecography and colonic transit time in assessing clinically obstructed women. Obstructed defaecation might not always be associated with abnormal colonic transit time. Likewise, not all constipated patients had signs of obstructed defaecation. The differential diagnosis between colonic slow transit constipation and constipation due to pelvic floor disorders is essential for an adequate strategy of care.

  20. Acute gastro-intestinal illness and its association with hydroclimatic factors in British Columbia, Canada: A time-series analysis

    NASA Astrophysics Data System (ADS)

    Galway, L. P.; Allen, D. M.

    2013-12-01

    Rising global temperatures and expected shifts in regional hydroclimatology in a changing climate are likely to influence the risk of infectious waterborne illness. This study examines the role of hydroclimatology as an underlying driver of the epidemiology of waterborne gastro-intestinal illness and contributes to our currently limited understanding of the possible ecosystem-mediated impacts of climate change on health. Using time-series regression analysis, we examine the associations between three hydroclimatic factors (monthly temperature, precipitation, and streamflow) and the monthly occurrence of AGI illness in two communities in the province of British Columbia, Canada. The two communities were selected as study sites to represent the dominant hydroclimatic regimes that characterize the province of BC: the rainfall-dominated hydroclimatic regime and snowmelt-dominated hydroclimatic regime Our results show that the number of monthly cases of AGI increased with increasing temperature, precipitation, and streamflow in the same month in the context of a rainfall-dominated regime and with increasing streamflow in the previous month in the context of a snowfall-dominated regime. These results suggest that hydroclimatic factors play a role in driving the occurrence and variability of AGI illness in this setting. Further, this study has highlighted that the nature and magnitude of the effects of hydroclimatic factors on waterborne illness vary across different hydroclimatic settings. We conclude that the watershed may be an appropriate context within which we can and should enhance our understanding of water-related climate change impacts on health. Examining the role of hydroclimatology as an underlying driver of the epidemiology of infectious disease is key to understanding of the possible ecosystem-mediated impacts of climate change on health and developing appropriate adaptation responses.

  1. TRANSIT MONITORING IN THE SOUTH (TraMoS) PROJECT: DISCARDING TRANSIT TIMING VARIATIONS IN WASP-5b

    SciTech Connect

    Hoyer, S.; Rojo, P.; Lopez-Morales, M. E-mail: pato@das.uchile.cl

    2012-03-20

    We report nine new transit epochs of the extrasolar planet WASP-5b, observed in the Bessell I band with the Southern Astrophysical Research Telescope at the Cerro Pachon Observatory and with the SMARTS 1 m Telescope at the Cerro Tololo Inter-American Observatory, between 2008 August and 2009 October. The new transits have been combined with all previously published transit data for this planet to provide a new Transit Timing Variation (TTV) analysis of its orbit. We find no evidence of TTV rms variations larger than 1 minute over a 3 year time span. This result discards the presence of planets more massive than about 5 M{sub Circled-Plus }, 1 M{sub Circled-Plus }, and 2 M{sub Circled-Plus} around the 1:2, 5:3, and 2:1 orbital resonances, respectively. These new detection limits exceed by {approx}5-30 times the limits imposed by current radial velocity observations in the mean motion resonances of this system. Our search for the variation of other parameters, such as orbital inclination and transit depth, also yields negative results over the total time span of the transit observations. This result supports formation theories that predict a paucity of planetary companions to hot Jupiters.

  2. Discovering the space-time dimensions of schedule padding and delay from GTFS and real-time transit data

    NASA Astrophysics Data System (ADS)

    Wessel, Nate; Widener, Michael J.

    2017-01-01

    Schedule padding is the extra time added to transit schedules to reduce the risk of delay. Where there is more random delay, there should be more schedule padding. While schedule padding is a product of transit planners, a method for detecting when and where it exists could provide valuable feedback as transit agencies continually develop their networks. By analyzing transit schedules and real-time vehicle location data at the level of stop-to-stop segments, we can locate padding in space and time and identify the places that may be most effected by stochastic delay. Such information could be used to target delay-reduction interventions such as fare prepayment or transit-only rights of way. The Toronto Transit Commission is used as a case study, and initial results suggest that highly delayed segments appear mostly in the expected, but some surprising, places.

  3. Colonic transit time is related to bacterial metabolism and mucosal turnover in the gut.

    PubMed

    Roager, Henrik M; Hansen, Lea B S; Bahl, Martin I; Frandsen, Henrik L; Carvalho, Vera; Gøbel, Rikke J; Dalgaard, Marlene D; Plichta, Damian R; Sparholt, Morten H; Vestergaard, Henrik; Hansen, Torben; Sicheritz-Pontén, Thomas; Nielsen, H Bjørn; Pedersen, Oluf; Lauritzen, Lotte; Kristensen, Mette; Gupta, Ramneek; Licht, Tine R

    2016-06-27

    Little is known about how colonic transit time relates to human colonic metabolism and its importance for host health, although a firm stool consistency, a proxy for a long colonic transit time, has recently been positively associated with gut microbial richness. Here, we show that colonic transit time in humans, assessed using radio-opaque markers, is associated with overall gut microbial composition, diversity and metabolism. We find that a long colonic transit time associates with high microbial richness and is accompanied by a shift in colonic metabolism from carbohydrate fermentation to protein catabolism as reflected by higher urinary levels of potentially deleterious protein-derived metabolites. Additionally, shorter colonic transit time correlates with metabolites possibly reflecting increased renewal of the colonic mucosa. Together, this suggests that a high gut microbial richness does not per se imply a healthy gut microbial ecosystem and points at colonic transit time as a highly important factor to consider in microbiome and metabolomics studies.

  4. Transitive Lie groups on S^1\\times S^{2m}

    NASA Astrophysics Data System (ADS)

    Gorbatsevich, Vladimir V.

    2007-10-01

    The structure of Lie groups acting transitively on the direct product of a circle and an even-dimensional sphere is described. For products of two spheres of dimension >1 a similar problem has already been solved by other authors. The minimal transitive Lie groups on S^1 and S^{2m} are also indicated. As an application of these results, the structure of the automorphism group of one class of geometric structures, generalized quadrangles (a special case of Tits buildings) is considered. A conjecture put forward by Kramer is proved: the automorphism group of a connected generalized quadrangle of type (1,2m) always contains a transitive subgroup that is the direct product of a compact simple Lie group and a one-dimensional Lie group. Bibliography: 16 titles.

  5. Feasibility and Timing of Cytoreduction Surgery in Advanced (Metastatic or Recurrent) Gastrointestinal Stromal Tumors During the Era of Imatinib

    PubMed Central

    Chang, Shih-Chun; Liao, Chien-Hung; Wang, Shang-Yu; Tsai, Chun-Yi; Chiang, Kun-Chun; Cheng, Chi-Tung; Yeh, Ta-Sen; Chen, Yen-Yang; MA, Ming-Chun; Liu, Chien-Ting; Yeh, Chun-Nan

    2015-01-01

    Abstract The prognosis of advanced gastrointestinal stromal tumors (GISTs) was dramatically improved in the era of imatinib. Cytoreduction surgery was advocated as an additional treatment for advanced GISTs, especially when patients having poor response to imatinib or developing resistance to it. However, the efficacy and benefit of cytoreduction were still controversial. Likewise, the sequence between cytoreduction surgery and imatinib still need evaluation. In this study, we tried to assess the feasibility and efficiency of cytoreduction in advanced GISTs. Furthermore, we analyzed the impact of timing of the cytoreduction surgery on the prognosis of advanced GISTs. We conducted a prospective collecting retrospective review of patients with advanced GISTs (metastatic, unresectable, and recurrent GISTs) treated in Chang Gung memorial hospital (CGMH) since 2001 to 2013. We analyzed the impact of cytoreduction surgery to response to imatinib, progression-free survival (PFS), and overall survival (OS) in patients with advanced GISTs. Moreover, by the timing of cytoreduction to imatinib, we divided the surgical patients who had surgery before imatinib use into early group and those who had surgery after imatinib into late. We compared the clinical response to imatinib, PFS and OS between early and late cytoreduction surgical groups. Totally, 182 patients were enrolled into this study. Seventy-six patients underwent cytoreduction surgery. The demographic characteristics and tumor presentation were similar between surgical and non-surgical groups. The surgical group showed better complete response rate (P < 0.001) and partial response rate (P = 0.008) than non-surgical group. The 1-year, 3-year, and 5-year PFS were significantly superior in surgical group (P = 0.003). The 1-year, 3-year, and 5-year OS were superior in surgical group, but without statistical significance (P = 0.088). Dividing by cytoreduction surgical timing, the demographic

  6. Transit Timing Observations from Kepler: III. Confirmation of 4 Multiple Planet Systems by a Fourier-Domain Study of Anti-correlated Transit Timing Variations

    SciTech Connect

    Steffen, Jason H.; Fabrycky, Daniel C.; Ford, Eric B.; Carter, Joshua A.; Fressin, Francois; Holman, Matthew J.; Lissauer, Jack J.; Rowe, Jason F.; Ragozzine, Darin; Welsh, William F.; Borucki, William J.; /NASA, Ames /UC, Santa Barbara

    2012-01-01

    We present a method to confirm the planetary nature of objects in systems with multiple transiting exoplanet candidates. This method involves a Fourier-domain analysis of the deviations in the transit times from a constant period that result from dynamical interactions within the system. The combination of observed anticorrelations in the transit times and mass constraints from dynamical stability allow us to claim the discovery of four planetary systems, Kepler-25, Kepler-26, Kepler-27 and Kepler-28, containing eight planets and one additional planet candidate.

  7. Decreasing Transition Times in Elementary School Classrooms: Using Computer-Assisted Instruction to Automate Intervention Components

    ERIC Educational Resources Information Center

    Hine, Jeffrey F.; Ardoin, Scott P.; Foster, Tori E.

    2015-01-01

    Research suggests that students spend a substantial amount of time transitioning between classroom activities, which may reduce time spent academically engaged. This study used an ABAB design to evaluate the effects of a computer-assisted intervention that automated intervention components previously shown to decrease transition times. We examined…

  8. How old is streamwater? Open questions in catchment transit time conceptualization, modeling and analysis

    Treesearch

    J.J. McDonnell; K. McGuire; P. Aggarwal; K.J. Beven; D. Biondi; G. Destouni; S. Dunn; A. James; J. Kirchner; P. Kraft; S. Lyon; P. Maloszewski; B. Newman; L. Pfister; A. Rinaldo; A. Rodhe; T. Sayama; J. Seibert; K. Solomon; C. Soulsby; M. Stewart; D. Tetzlaff; C. Tobin; P. Troch; M. Weiler; A. Western; A. Wörman; S. Wrede

    2010-01-01

    The time water spends travelling subsurface through a catchment to the stream network (i.e. the catchment water transit time) fundamentally describes the storage, flow pathway heterogeneity and sources of water in a catchment. The distribution of transit times reflects how catchments retain and release water and solutes that in turn set biogeochemical conditions and...

  9. Transit time homogenization in ischemic stroke - A novel biomarker of penumbral microvascular failure?

    PubMed

    Engedal, Thorbjørn S; Hjort, Niels; Hougaard, Kristina D; Simonsen, Claus Z; Andersen, Grethe; Mikkelsen, Irene Klærke; Boldsen, Jens K; Eskildsen, Simon F; Hansen, Mikkel B; Angleys, Hugo; Jespersen, Sune N; Pedraza, Salvador; Cho, Tae H; Serena, Joaquín; Siemonsen, Susanne; Thomalla, Götz; Nighoghossian, Norbert; Fiehler, Jens; Mouridsen, Kim; Østergaard, Leif

    2017-01-01

    Cerebral ischemia causes widespread capillary no-flow in animal studies. The extent of microvascular impairment in human stroke, however, is unclear. We examined how acute intra-voxel transit time characteristics and subsequent recanalization affect tissue outcome on follow-up MRI in a historic cohort of 126 acute ischemic stroke patients. Based on perfusion-weighted MRI data, we characterized voxel-wise transit times in terms of their mean transit time (MTT), standard deviation (capillary transit time heterogeneity - CTH), and the CTH:MTT ratio (relative transit time heterogeneity), which is expected to remain constant during changes in perfusion pressure in a microvasculature consisting of passive, compliant vessels. To aid data interpretation, we also developed a computational model that relates graded microvascular failure to changes in these parameters. In perfusion-diffusion mismatch tissue, prolonged mean transit time (>5 seconds) and very low cerebral blood flow (≤6 mL/100 mL/min) was associated with high risk of infarction, largely independent of recanalization status. In the remaining mismatch region, low relative transit time heterogeneity predicted subsequent infarction if recanalization was not achieved. Our model suggested that transit time homogenization represents capillary no-flow. Consistent with this notion, low relative transit time heterogeneity values were associated with lower cerebral blood volume. We speculate that low RTH may represent a novel biomarker of penumbral microvascular failure.

  10. Transition to daylight saving time reduces sleep duration plus sleep efficiency of the deprived sleep.

    PubMed

    Lahti, Tuuli A; Leppämäki, Sami; Lönnqvist, Jouko; Partonen, Timo

    2006-10-09

    Daylight saving time (DST) is widely adopted. We explored the effects of transition to daylight saving time on sleep. With the use of wrist-worn accelerometers, we monitored the rest-activity cycles on a sample of 10 healthy adults for 10 days around the transition to summer time. Identical measurement protocols were carried out twice on the same individuals during the transitions in the years of 2003 and 2004, yielding data on 200 person-days for analysis. Both sleep duration and sleep efficiency were reduced after the transition both years. After the transition sleep time was shortened by 60.14min (P<0.01) and sleep efficiency was reduced by 10% (P<0.01) on average. Transition to daylight saving time appears to compromise the process of sleep by decreasing both sleep duration and sleep efficiency.

  11. Transitions.

    ERIC Educational Resources Information Center

    Agnew, Jeanne L.; Choike, James R.

    1987-01-01

    Mathematical observations are made about some continuous curves, called transitions, encountered in well-known experiences. The transition parabola, the transition spiral, and the sidestep maneuver are presented. (MNS)

  12. Transitions into and out of daylight saving time compromise sleep and the rest-activity cycles

    PubMed Central

    Lahti, Tuuli A; Leppämäki, Sami; Lönnqvist, Jouko; Partonen, Timo

    2008-01-01

    Background The aim of this study was to analyze the effects of transition out of and into daylight saving time on the rest-activity cycles and sleep. Rest-activity cycles of nine healthy participants aged 20 to 40 years were measured around transitions out of and into daylight saving time on fall 2005 and spring 2006 respectively. Rest-activity cycles were measured using wrist-worn accelerometers. The participants filled in the Morningness-Eveningness and Seasonal Pattern Assessment Questionnaires before starting the study and kept a sleep diary during the study. Results Fall transition was more disturbing for the more morning type and spring transition for the more evening type of persons. Individuals having a higher global seasonality score suffered more from the transitions. Conclusion Transitions out of and into daylight saving time enhanced night-time restlessness and thereby compromised the quality of sleep. PMID:18269740

  13. Transitions into and out of daylight saving time compromise sleep and the rest-activity cycles.

    PubMed

    Lahti, Tuuli A; Leppämäki, Sami; Lönnqvist, Jouko; Partonen, Timo

    2008-02-12

    The aim of this study was to analyze the effects of transition out of and into daylight saving time on the rest-activity cycles and sleep. Rest-activity cycles of nine healthy participants aged 20 to 40 years were measured around transitions out of and into daylight saving time on fall 2005 and spring 2006 respectively. Rest-activity cycles were measured using wrist-worn accelerometers. The participants filled in the Morningness-Eveningness and Seasonal Pattern Assessment Questionnaires before starting the study and kept a sleep diary during the study. Fall transition was more disturbing for the more morning type and spring transition for the more evening type of persons. Individuals having a higher global seasonality score suffered more from the transitions. Transitions out of and into daylight saving time enhanced night-time restlessness and thereby compromised the quality of sleep.

  14. No Timing Variations Observed in Third Transit of Snow-line Exoplanet Kepler-421b

    NASA Astrophysics Data System (ADS)

    Dalba, Paul A.; Muirhead, Philip S.

    2016-07-01

    We observed Kepler-421 during the anticipated third transit of the snow-line exoplanet Kepler-421b in order to constrain the existence and extent of transit timing variations (TTVs). Previously, the Kepler spacecraft only observed two transits of Kepler-421b, leaving the planet’s transit ephemeris unconstrained. Our visible light, time-series observations from the 4.3 m Discovery Channel Telescope were designed to capture pre-transit baseline and the partial transit of Kepler-421b, barring significant TTVs. We use the light curves to assess the probabilities of various transit models using both the posterior odds ratio and the Bayesian Information Criterion, and find that a transit model with no TTVs is favored to 3.6σ confidence. These observations suggest that Kepler-421b is either alone in its system or is only experiencing minor dynamic interactions with an unseen companion. With the Kepler-421b ephemeris constrained, we calculate future transit times and discuss the opportunity to characterize the atmosphere of this cold, long-period exoplanet via transmission spectroscopy. Our investigation emphasizes the difficulties associated with observing long-period exoplanet transits and the consequences that arise from failing to refine transit ephemerides.

  15. How many segments are necessary to characterize delayed colonic transit time?

    PubMed

    Bouchoucha, Michel; Devroede, Ghislain; Bon, Cyriaque; Raynaud, Jean-Jacques; Bejou, Bakhtiar; Benamouzig, Robert

    2015-10-01

    Measuring colonic transit time with radiopaque markers is simple, inexpensive, and very useful in constipated patients. Yet, the algorithm used to identify colonic segments is subjective, rather than founded on prior experimentation. The aim of the present study is to describe a rational way to determine the colonic partition in the measurement of colonic transit time. Colonic transit time was measured in seven segments: ascending colon, hepatic flexure, right and left transverse colon, splenic flexure, descending colon, and rectosigmoid in 852 patients with functional bowel and anorectal disorders. An unsupervised algorithm for modeling Gaussian mixtures served to estimate the number of subgroups from this oversegmented colonic transit time. After that, we performed a k-means clustering that separated the observations into homogenous groups of patients according to their oversegmented colonic transit time. The Gaussian mixture followed by the k-means clustering defined 4 populations of patients: "normal and fast transit" (n = 548) and three groups of patients with delayed colonic transit time "right delay" (n = 82) in which transit is delayed in the right part of the colon, "left delay" (n = 87) with transit delayed in the left part of colon and "outlet constipation" (n = 135) for patients with transit delayed in the terminal intestine. Only 3.7 % of patients were "erroneously" classified in the 4 groups recognized by clustering. This unsupervised analysis of segmental colonic transit time shows that the classical division of the colon and the rectum into three segments is sufficient to characterize delayed segmental colonic transit time.

  16. Hillslope permeability architecture controls on subsurface transit time distribution and flow paths

    NASA Astrophysics Data System (ADS)

    Ameli, A. A.; Amvrosiadi, N.; Grabs, T.; Laudon, H.; Creed, I. F.; McDonnell, J. J.; Bishop, K.

    2016-12-01

    Defining the catchment transit time distribution remains a challenge. Here, we used a new semi-analytical physically-based integrated subsurface flow and advective-dispersive particle movement model to assess the subsurface controls on subsurface water flow paths and transit time distributions. First, we tested the efficacy of the new model for simulation of the observed groundwater dynamics at the well-studied S-transect hillslope (Västrabäcken sub-catchment, Sweden). This system, like many others, is characterized by exponential decline in saturated hydraulic conductivity and porosity with soil depth. The model performed well relative to a tracer-based estimate of transit time distribution as well as observed groundwater depth-discharge relationship within 30 m of the stream. Second, we used the model to assess the effect of changes in the subsurface permeability architecture on flow pathlines and transit time distribution in a set of virtual experiments. Vertical patterns of saturated hydraulic conductivity and porosity with soil depth significantly influenced hillslope transit time distribution. Increasing infiltration rates significantly decreased mean groundwater age, but not the distribution of transit times relative to mean groundwater age. The location of hillslope hydrologic boundaries, including the groundwater divide and no-flow boundary underlying the hillslope, changed the transit time distribution less markedly. These results can guide future decisions on the degree of complexity that is warranted in a physically-based rainfall-runoff model to efficiently and explicitly estimate time invariant subsurface pathlines and transit time distribution.

  17. Hydrogen breath test assessment of orocecal transit time: comparison with barium meal study.

    PubMed

    Hirakawa, M; Iida, M; Kohrogi, N; Fujishima, M

    1988-12-01

    Orocecal transit time was measured simultaneously by the hydrogen breath test and a barium meal study in 12 hospitalized patients, the objective being to determine whether the former test accurately represents the orocecal transit time, and to establish an adequate criterion for the transit time, based on the former test. Two definitions of orocecal transit time by the hydrogen breath test were evaluated: the time from lactulose ingestion to a sustained increase of over 5 ppm above fasting levels in the end-expiratory hydrogen concentration (definition A) and the interval to that of over 10 ppm (definition B). The orocecal transit time measured by the radiologic method was 63 +/- 9 min (mean +/- SEM), whereas that using definition A of the hydrogen breath test was 74 +/- 9 min, and that using definition B was 87 +/- 10 min. Transit times determined by both definitions closely correlated with that obtained by the radiologic method (A, r = 0.86, p less than 0.01; B, r = 0.81, p less than 0.01). Therefore, elevation of end-expiratory hydrogen concentrations seemed to coincide with cecal appearance of the head of the lactulose load. When the mean transit times were compared with findings in case of the radiologic method, definition A rather than B appeared to be more appropriate to determine orocecal transit time.

  18. Transitions.

    ERIC Educational Resources Information Center

    Nathanson, Jeanne H., Ed.

    1993-01-01

    This theme issue on transitions for individuals with disabilities contains nine papers discussing transition programs and issues. "Transition Issues for the 1990s," by Michael J. Ward and William D. Halloran, discusses self-determination, school responsibility for transition, continued educational engagement of at-risk students, and service…

  19. The physical origins of transit time measurements for rapid, single cell mechanotyping.

    PubMed

    Nyberg, Kendra D; Scott, Michael B; Bruce, Samuel L; Gopinath, Ajay B; Bikos, Dimitri; Mason, Thomas G; Kim, Jin Woong; Choi, Hong Sung; Rowat, Amy C

    2016-08-16

    The mechanical phenotype or 'mechanotype' of cells is emerging as a potential biomarker for cell types ranging from pluripotent stem cells to cancer cells. Using a microfluidic device, cell mechanotype can be rapidly analyzed by measuring the time required for cells to deform as they flow through constricted channels. While cells typically exhibit deformation timescales, or transit times, on the order of milliseconds to tens of seconds, transit times can span several orders of magnitude and vary from day to day within a population of single cells; this makes it challenging to characterize different cell samples based on transit time data. Here we investigate how variability in transit time measurements depends on both experimental factors and heterogeneity in physical properties across a population of single cells. We find that simultaneous transit events that occur across neighboring constrictions can alter transit time, but only significantly when more than 65% of channels in the parallel array are occluded. Variability in transit time measurements is also affected by the age of the device following plasma treatment, which could be attributed to changes in channel surface properties. We additionally investigate the role of variability in cell physical properties. Transit time depends on cell size; by binning transit time data for cells of similar diameters, we reduce measurement variability by 20%. To gain further insight into the effects of cell-to-cell differences in physical properties, we fabricate a panel of gel particles and oil droplets with tunable mechanical properties. We demonstrate that particles with homogeneous composition exhibit a marked reduction in transit time variability, suggesting that the width of transit time distributions reflects the degree of heterogeneity in subcellular structure and mechanical properties within a cell population. Our results also provide fundamental insight into the physical underpinnings of transit measurements

  20. Regularity and stability of transition fronts in nonlocal equations with time heterogeneous ignition nonlinearity

    NASA Astrophysics Data System (ADS)

    Shen, Wenxian; Shen, Zhongwei

    2017-03-01

    The present paper is devoted to the investigation of various properties of transition fronts in one-dimensional nonlocal equations in heterogeneous media of ignition type, whose existence has been established by the authors of the present paper in a previous work. It is first shown that transition fronts are continuously differentiable in space with uniformly bounded and uniformly Lipschitz continuous space partial derivative. This is the first time that space regularity of transition fronts in nonlocal equations is ever studied. It is then shown that transition fronts are uniformly steep. Finally, asymptotic stability, in the sense of exponentially attracting front-like initial data, of transition fronts is studied.

  1. Orbital parameter estimation of extrasolar multi-planet systems by Transit Time Variation

    NASA Astrophysics Data System (ADS)

    Korth, J.; Grziwa, S.; Pätzold, M.

    2014-04-01

    Transit Time Variation (TTV) is the earlier or later occurrence of a planetary transit relative to the time of a reference transit. TTV may be dominantly caused by the gravitational perturbation of the orbit of the transiting planet by another still unknown planet(s) inside or outside of the orbit of the known transiting planet. Gravitational interactions perturb the velocity of the transiting planet in its orbit which manifests in the periodical perturbation of the revolution period. Measurements of the transit times and the identification of differences from a mean transit period may then indicate the presence of another unknown planet and is therefore proof for the existence of further planets. The estimation of the mass of the transiting planet and the orbital parameters of the undetected planet(s) are constrained by the amplitude of the periodical variation of the transit times. Simulations of known multi-planet systems which show TTV shall be presented. The resulting TTV amplitude is analyzed with regard to the main dependencies: mass of the perturbing planet and the orbit eccentricities.

  2. Relationship between longitudinal stress wave transit time and moisture content of lumber during kiln-drying

    Treesearch

    William T. Simpson; Xiping. Wang

    2001-01-01

    The relationship between longitudinal stress wave transit time and wood moisture content (MC) was examined as a potential means of estimating MC control points in dry kiln schedules for lumber. A linear relationship was found between the relative transit time and the average MC of sugar maple and ponderosa pine boards dried according to typical kiln schedules.

  3. Integral definition of transition time in the Landau-Zener model

    SciTech Connect

    Yan Yue; Wu Biao

    2010-02-15

    We give a general definition for the transition time in the Landau-Zener model. This definition allows us to compute numerically the Landau-Zener transition time at any sweeping rate without ambiguity in both diabatic and adiabatic bases. With this new definition, analytical results are obtained in both the adiabatic limit and the sudden limit.

  4. Gastrointestinal cancer

    SciTech Connect

    Levin, B.

    1988-01-01

    This book contains 33 selections. Some of the titles are: The natural history of colorectal cancer; opportunities for intervention; Radiotherapy for early rectal cancer; Intraoperative irradiation for gastrointestinal cancers; Hepatocellular carcinoma; clinical presentation, etiology, and prevention; and Current issues in the treatment of patients with gastric cancer.

  5. Magnetic resonance imaging biomarkers of gastrointestinal motor function and fluid distribution

    PubMed Central

    Khalaf, Asseel; Hoad, Caroline L; Spiller, Robin C; Gowland, Penny A; Moran, Gordon W; Marciani, Luca

    2015-01-01

    Magnetic resonance imaging (MRI) is a well established technique that has revolutionized diagnostic radiology. Until recently, the impact that MRI has had in the assessment of gastrointestinal motor function and bowel fluid distribution in health and in disease has been more limited, despite the novel insights that MRI can provide along the entire gastrointestinal tract. MRI biomarkers include intestinal motility indices, small bowel water content and whole gut transit time. The present review discusses new developments and applications of MRI in the upper gastrointestinal tract, the small bowel and the colon reported in the literature in the last 5 years. PMID:26600972

  6. Generalizing memories over time: sleep and reinforcement facilitate transitive inference.

    PubMed

    Werchan, Denise M; Gómez, Rebecca L

    2013-02-01

    The use of reinforcement and rewards is known to enhance memory retention. However, the impact of reinforcement on higher-order forms of memory processing, such as integration and generalization, has not been directly manipulated in previous studies. Furthermore, there is evidence that sleep enhances the integration and generalization of memory, but these studies have only used reinforcement learning paradigms and have not examined whether reinforcement impacts or is critical for memory integration and generalization during sleep. Thus, the aims of the current study were to examine: (1) whether reinforcement during learning impacts the integration and generalization of memory; and (2) whether sleep and reinforcement interact to enhance memory integration and generalization. We investigated these questions using a transitive inference (TI) task, which is thought to require the integration and generalization of disparate relational memories in order to make novel inferences. To examine whether reinforcement influences or is required for the formation of inferences, we compared performance using a reinforcement or an observation based TI task. We examined the impact of sleep by comparing performance after a 12-h delay containing either wake or sleep. Our results showed that: (1) explicit reinforcement during learning is required to make transitive inferences and that sleep further enhances this effect; (2) sleep does not make up for the inability to make inferences when reinforcement does not occur during learning. These data expand upon previous findings and suggest intriguing possibilities for the mechanisms involved in sleep-dependent memory transformation.

  7. Mapping the Timing, Pace, and Scale of the Fertility Transition in Brazil.

    PubMed

    Potter, Joseph E; Schmertmann, Carl P; Assunção, Renato M; Cavenaghi, Suzana M

    2010-01-01

    Between 1960 and 2000, fertility fell sharply in Brazil, but this transition was unevenly distributed in space and time. Using Bayesian spatial statistical methods and microdata from five censuses, we develop and apply a procedure for fitting logistic curves to the fertility transitions in more than 500 small regions of Brazil over this 40-year period. Doing so enables us to map the main features of the Brazilian fertility transition in considerable detail. We detect early declines in some regions of the country and document large differences between early and late transitions in regard to both the initial level of fertility and the speed of the transition. We also use our results to test hypotheses regarding changes in the level of development at the onset of the fertility transition and identify a temporary stall in the Brazilian transition that occurred in the late 1990s. A web site with project details is at http://schmert.net/BayesLogistic.

  8. Does the transition into daylight saving time really cause partial sleep deprivation?

    PubMed

    Toth Quintilham, Manoel Carlos; Adamowicz, Taísa; Pereira, Erico Felden; Pedrazzoli, Mario; Louzada, Fernando Mazzilli

    2014-01-01

    To identify possible changes in the sleep patterns according to chronotype in undergraduate students during the daylight saving time (DST) transition. A total of 378 students answered the Morningness-Eveningness Questionnaire (MEQ) to determine their chronotype and kept a diary about sleep-wake schedules 1 week before and after the DST transition. Oral mucosal cell samples were collected for genetic analysis. After the DST transition, intermediate types (I-types) delayed bedtime and increased their time in bed and all groups delayed their wake-up time. All groups presented a shorter phase angle between sunset and the bedtime after the DST transition. On the other hand, only E-types showed a tendency to reduce the phase angle between sunrise and wake-up time, while I-types and M-types kept the same phase angles between sunrise and wake-up time after the DST transition. The polymorphisms in the human genes CLOCK and PER3 were not associated with individual differences in sleep patterns, nor were they associated with an adjustment to the DST transition. Under the new set of social times determined by DST, the adjustment was only partial. I-types delayed bedtime and all groups delayed their wake-up times after the beginning of DST. Consequently, the time in bed after the DST transition was not reduced; Morning (M-types) and Evening-types (E-types) kept the same time in bed and I-types showed an increase on it.

  9. Investigation of Timing to Switch Control Mode in Powered Knee Prostheses during Task Transitions

    PubMed Central

    Zhang, Fan; Liu, Ming; Huang, He

    2015-01-01

    Current powered prosthetic legs require switching control modes according to the task the user is performing (e.g. level-ground walking, stair climbing, walking on slopes, etc.). To allow prosthesis users safely and seamlessly transition between tasks, it is critical to determine when to switch the prosthesis control mode during task transitions. Our previous study defined critical timings for different types of task transitions in ambulation; however, it is unknown whether it is the unique timing that allows safe and seamless transitions. The goals of this study were to (1) systematically investigate the effects of mode switch timing on the prosthesis user’s performance in task transitions, and (2) identify appropriate timing to switch the prosthesis control mode so that the users can seamlessly transition between different locomotion tasks. Five able-bodied (AB) and two transfemoral (TF) amputee subjects were tested as they wore a powered knee prosthesis. The prosthesis control mode was switched manually at various times while the subjects performed different types of task transitions. The subjects’ task transition performances were evaluated by their walking balance and success in performing seamless task transitions. The results demonstrated that there existed a time window within which switching the prosthesis control mode neither interrupted the subjects’ task transitions nor disturbed their walking balance. Therefore, the results suggested the control mode switching of a lower limb prosthesis can be triggered within an appropriate time window instead of a specific timing or an individual phase. In addition, a generalized criterion to determine the appropriate mode switch timing was proposed. The outcomes of this study could provide important guidance for future designs of neurally controlled powered knee prostheses that are safe and reliable to use. PMID:26197084

  10. Investigation of Timing to Switch Control Mode in Powered Knee Prostheses during Task Transitions.

    PubMed

    Zhang, Fan; Liu, Ming; Huang, He

    2015-01-01

    Current powered prosthetic legs require switching control modes according to the task the user is performing (e.g. level-ground walking, stair climbing, walking on slopes, etc.). To allow prosthesis users safely and seamlessly transition between tasks, it is critical to determine when to switch the prosthesis control mode during task transitions. Our previous study defined critical timings for different types of task transitions in ambulation; however, it is unknown whether it is the unique timing that allows safe and seamless transitions. The goals of this study were to (1) systematically investigate the effects of mode switch timing on the prosthesis user's performance in task transitions, and (2) identify appropriate timing to switch the prosthesis control mode so that the users can seamlessly transition between different locomotion tasks. Five able-bodied (AB) and two transfemoral (TF) amputee subjects were tested as they wore a powered knee prosthesis. The prosthesis control mode was switched manually at various times while the subjects performed different types of task transitions. The subjects' task transition performances were evaluated by their walking balance and success in performing seamless task transitions. The results demonstrated that there existed a time window within which switching the prosthesis control mode neither interrupted the subjects' task transitions nor disturbed their walking balance. Therefore, the results suggested the control mode switching of a lower limb prosthesis can be triggered within an appropriate time window instead of a specific timing or an individual phase. In addition, a generalized criterion to determine the appropriate mode switch timing was proposed. The outcomes of this study could provide important guidance for future designs of neurally controlled powered knee prostheses that are safe and reliable to use.

  11. Time Resolved Phase Transitions via Dynamic Transmission Electron Microscopy

    SciTech Connect

    Reed, B W; Armstrong, M R; Blobaum, K J; Browning, N D; Burnham, A K; Campbell, G H; Gee, R; Kim, J S; King, W E; Maiti, A; Piggott, W T; Torralva, B R

    2007-02-22

    The Dynamic Transmission Electron Microscope (DTEM) project is developing an in situ electron microscope with nanometer- and nanosecond-scale resolution for the study of rapid laser-driven processes in materials. We report on the results obtained in a year-long LDRD-supported effort to develop DTEM techniques and results for phase transitions in molecular crystals, reactive multilayer foils, and melting and resolidification of bismuth. We report the first in situ TEM observation of the HMX {beta}-{delta} phase transformation in sub-{micro}m crystals, computational results suggesting the importance of voids and free surfaces in the HMX transformation kinetics, and the first electron diffraction patterns of intermediate states in fast multilayer foil reactions. This project developed techniques which are applicable to many materials systems and will continue to be employed within the larger DTEM effort.

  12. Frequency of Close Companions among Kepler Planets—a Transit Time Variation Study

    NASA Astrophysics Data System (ADS)

    Xie, Ji-Wei; Wu, Yanqin; Lithwick, Yoram

    2014-07-01

    A transiting planet exhibits sinusoidal transit time variations (TTVs) if perturbed by a companion near a mean-motion resonance. We search for sinusoidal TTVs in more than 2600 Kepler candidates, using the publicly available Kepler light curves (Q0-Q12). We find that the TTV fractions rise strikingly with the transit multiplicity. Systems where four or more planets transit enjoy a TTV fraction that is roughly five times higher than those where a single planet transits, and about twice as high as those for doubles and triples. In contrast, models in which all transiting planets arise from similar dynamical configurations predict comparable TTV fractions among these different systems. One simple explanation for our results is that there are at least two different classes of Kepler systems, one closely packed and one more sparsely populated.

  13. Frequency of close companions among Kepler planets—a transit time variation study

    SciTech Connect

    Xie, Ji-Wei; Wu, Yanqin; Lithwick, Yoram E-mail: wu@astro.utoronto.ca

    2014-07-10

    A transiting planet exhibits sinusoidal transit time variations (TTVs) if perturbed by a companion near a mean-motion resonance. We search for sinusoidal TTVs in more than 2600 Kepler candidates, using the publicly available Kepler light curves (Q0-Q12). We find that the TTV fractions rise strikingly with the transit multiplicity. Systems where four or more planets transit enjoy a TTV fraction that is roughly five times higher than those where a single planet transits, and about twice as high as those for doubles and triples. In contrast, models in which all transiting planets arise from similar dynamical configurations predict comparable TTV fractions among these different systems. One simple explanation for our results is that there are at least two different classes of Kepler systems, one closely packed and one more sparsely populated.

  14. The use of transit timing to detect terrestrial-mass extrasolar planets.

    PubMed

    Holman, Matthew J; Murray, Norman W

    2005-02-25

    Future surveys for transiting extrasolar planets are expected to detect hundreds of jovian-mass planets and tens of terrestrial-mass planets. For many of these newly discovered planets, the intervals between successive transits will be measured with an accuracy of 0.1 to 100 minutes. We show that these timing measurements will allow for the detection of additional planets in the system (not necessarily transiting) by their gravitational interaction with the transiting planet. The transit-time variations depend on the mass of the additional planet, and in some cases terrestrial-mass planets will produce a measurable effect. In systems where two planets are seen to transit, the density of both planets can be determined without radial-velocity observations.

  15. TEE, an estimator for the precision of eclipse and transit minimum times

    NASA Astrophysics Data System (ADS)

    Deeg, H. J.; Tingley, B.

    2017-03-01

    Context. Transit or eclipse timing variations have proven to be a valuable tool in exoplanet research. However, no simple way to estimate the potential precision of such timing measures has been presented yet, nor are guidelines available regarding the relation between timing errors and sampling rate. Aims: A timing error estimator (TEE) equation is presented that requires only basic transit parameters as input. With the TEE, estimating timing precision for actual data and for future instruments, such as the TESS and PLATO space missions, is straightforward. Methods: A derivation of the timing error based on a trapezoidal transit shape is given. We also verify the TEE on realistically modelled transits using Monte Carlo simulations and determine its validity range, exploring in particular the interplay between ingress/egress times and sampling rates. Results: The simulations show that the TEE gives timing errors very close to the correct value, as long as the temporal sampling is faster than transit ingress/egress durations and transits with very low S/N are avoided. Conclusions: The TEE is a useful tool for estimating eclipse or transit timing errors in actual and future data sets. In combination with a previously published equation to estimate period-errors, predictions for the ephemeris precision of long-coverage observations are possible as well. The tests for the TEE's validity range also led to implications for instrumental design. Temporal sampling has to be faster than transit ingress or egress durations, or a loss in timing precision will occur. An application to the TESS mission shows that transits close to its detection limit will have timing uncertainties that exceed 1 h within a few months of their acquisition. Prompt follow-up observations will be needed to avoid "losing" their ephemerides.

  16. Modeling unsteady lumped transport with time-varying transit time distributions

    NASA Astrophysics Data System (ADS)

    Harman, Ciaran

    2014-05-01

    Transit time distributions (TTD) offer a powerful tool for characterizing 'lumped' hydrologic transport (i.e. with few parameters, and without resolving the internal dynamics), but their general application for transport modeling has been hampered by the challenge of dealing with time-variable TTD. A way forward has emerged with the development of the 'age function' approach, but it has not been clear how to parameterize the age function, or how to interpret it physically and compare it to perceptual models. It also requires specification of the total storage, which is not possible in many cases of interest. This paper presents a more general formulation for TTD modeling that addresses these limitations. Transport is parameterized in terms of a probability density function Ω that represents the relative contribution of age-ranked water in storage to the flux out. Other frameworks are shown to be a special case of this one if the total storage is known. A new equation is obtained describing the time-evolution of the TTD that does not require specification of the total storage. In fact, the storage can be indefinitely large, allowing pdfs with semi-infinite support to parameterize Ω. Classical equations for random-sampling ('completely mixed') and piston-flow type transport fall out as special cases of Ω at steady-state. Other choices for Ω yield TTD capable of replicating observed transport phenomena like heavy tails and fractal 1/f-noise. Application of the model to long term and high frequency passive tracer datasets demonstrates its promise as a framework for new models of transport in time-variable landscape hydrologic systems with a unique ability to capture these important features.

  17. Travel time based approach for the assessment of vulnerability of karst groundwater: the Transit Time Method

    NASA Astrophysics Data System (ADS)

    Brosig, Karolin; Geyer, Tobias; Subah, Ali; Sauter, Martin

    2008-05-01

    Karst aquifers represent important water resources in many parts of the world. Unfortunately, karst aquifers are characterised by high contamination risks. This paper presents a travel time based method for the estimation of karst groundwater vulnerability. It considers (1) physics-based lateral flow within the uppermost weathered zone (epikarst) in a limestone-dominated region and (2) high velocities of vertical infiltration at discrete infiltration points (e.g. sinkholes) or lines (e.g. dry valleys, faults). Consequently, the Transit Time Method honours the actual flow path within the unsaturated zone of a karst aquifer system. A test site in Northern Jordan was chosen for the demonstration of the assessment technique, i.e. the catchment area of the Qunayyah Spring north of the capital Amman. The results demonstrate that zones of highest vulnerability lie within valleys and nearby main fault zones. It also reveals that regions, categorised as protected areas by other methods due to thick unsaturated zones, contribute to a major degree to the total risk.

  18. Malabsorption, Orocecal Transit Time and Small Intestinal Bacterial Overgrowth in Type 2 Diabetic Patients: A Connection.

    PubMed

    Rana, S V; Malik, Aastha; Bhadada, Sanjay K; Sachdeva, Naresh; Morya, Rajesh Kumar; Sharma, Gaurav

    2017-03-01

    Type 2 diabetes mellitus consists of dysfunctions characterized by hyperglycemia and resulting from combination of resistance to insulin action and inadequate insulin secretion. Most of diabetic patients report significant gastrointestinal symptoms. Entire GI tract can be affected by diabetes from oral cavity to large bowel and anorectal region. Proteins, carbohydrates, fats, and most fluids are absorbed in small intestine. Malabsorption may occurs when proper absorption of nutrients does not take place due to bacterial overgrowth or altered gut motility. The present study was planned to measure various malabsorption parameters in type 2 diabetic patients. 175 patients and 175 age and sex matched healthy controls attending Endocrinology Clinic in PGI, Chandigarh were enrolled. Lactose intolerance was measured by using non-invasive lactose hydrogen breath test. Urinary d-xylose and fecal fat were estimated using standard methods. Orocecal transit time and small intestinal bacterial overgrowth were measured using non-invasive lactulose and glucose breath test respectively. Out of 175 diabetic patients enrolled, 87 were males while among 175 healthy subjects 88 were males. SIBO was observed in 14.8 % type 2 diabetic patients and in 2.8 % of controls. There was statistically significant increase (p < 0.002) in OCTT in type 2 diabetic patients compared with controls. OCTT was observed to be more delayed (p < 0.003) in patients who were found to have SIBO than in patients without SIBO. Lactose intolerance was observed in 60 % diabetic patients and 39.4 % in controls. Urinary d-xylose levels were also lower in case of diabetic patients but no significant difference was found in 72 h fecal fat excretion among diabetic patients and controls. Urinary d-xylose and lactose intolerance in SIBO positive type 2 diabetic patients was more severe as compared to SIBO negative diabetic patients. From this study we can conclude that delayed OCTT may have led to SIBO which may

  19. Transitions.

    ERIC Educational Resources Information Center

    Field, David; And Others

    1992-01-01

    Includes four articles: "Career Aspirations" (Field); "Making the Transition to a New Curriculum" (Baker, Householder); "How about a 'Work to School' Transition?" (Glasberg); and "Technological Improvisation: Bringing CNC to Woodworking" (Charles, McDuffie). (SK)

  20. Solid volume fraction estimation of bone:marrow replica models using ultrasound transit time spectroscopy.

    PubMed

    Wille, Marie-Luise; Langton, Christian M

    2016-02-01

    The acceptance of broadband ultrasound attenuation (BUA) for the assessment of osteoporosis suffers from a limited understanding of both ultrasound wave propagation through cancellous bone and its exact dependence upon the material and structural properties. It has recently been proposed that ultrasound wave propagation in cancellous bone may be described by a concept of parallel sonic rays; the transit time of each ray defined by the proportion of bone and marrow propagated. A Transit Time Spectrum (TTS) describes the proportion of sonic rays having a particular transit time, effectively describing the lateral inhomogeneity of transit times over the surface aperture of the receive ultrasound transducer. The aim of this study was to test the hypothesis that the solid volume fraction (SVF) of simplified bone:marrow replica models may be reliably estimated from the corresponding ultrasound transit time spectrum. Transit time spectra were derived via digital deconvolution of the experimentally measured input and output ultrasonic signals, and compared to predicted TTS based on the parallel sonic ray concept, demonstrating agreement in both position and amplitude of spectral peaks. Solid volume fraction was calculated from the TTS; agreement between true (geometric calculation) with predicted (computer simulation) and experimentally-derived values were R(2)=99.9% and R(2)=97.3% respectively. It is therefore envisaged that ultrasound transit time spectroscopy (UTTS) offers the potential to reliably estimate bone mineral density and hence the established T-score parameter for clinical osteoporosis assessment.

  1. The role of hillslopes in stream flow response: connectivity, flow path, and transit time

    NASA Astrophysics Data System (ADS)

    McGuire, K. J.; McDonnell, J. J.

    2006-12-01

    Subsurface flow from hillslopes is widely recognized as an important contributor to stream flow generation; however, processes that control how and when hillslopes connect to streams remain unclear. Much of the difficulty in deciphering hillslope response in the stream is due to riparian zone modulation of these inputs. We investigated stream and hillslope runoff dynamics in a 10 ha catchment in the western Cascades of Oregon where the riparian zone has been removed by debris flows, providing an unambiguous hillslope hydrologic signal to the stream channel. Water transit time was used as a framework to develop a conceptual stream flow generation model for the small basin. We based our conceptualization on observations of hydrometric, stable isotope, and applied tracer responses and computed transit times for multiple runoff components using a simple linear systems model. Event water mean transit times (8 to 34 h) and rapid breakthrough from applied hillslope tracer additions, demonstrated that contributing areas extend far upslope during events. Despite rapid hillslope transport processes during events, vadose zone water and runoff mean transit times during non-storm conditions were greater than the timescale of storm events. Vadose zone water mean transit times ranged between 10 and 25 days. Hillslope seepage and catchment baseflow mean transit times were between 1 and 2 years. We describe a conceptual model that captures variable physical flow pathways and transit times through changing antecedent wetness conditions that illustrate the different stages of hillslope and stream connectivity.

  2. [Gastrointestinal bezoars].

    PubMed

    Espinoza González, Ricardo

    2016-08-01

    Gastrointestinal bezoars are a concretion of indigested material that can be found in the gastrointestinal tract of humans and some animals. This material forms an intraluminal mass, more commonly located in the stomach. During a large period of history animal bezoars were considered antidotes to poisons and diseases. We report a historical overview since bezoars stones were thought to have medicinal properties. This magic conception was introduced in South America by Spanish conquerors. In Chile, bezoars are commonly found in a camelid named guanaco (Lama guanicoe). People at Central Chile and the Patagonia believed that bezoar stones had magical properties and they were traded at very high prices. In Santiago, during the eighteenth century the Jesuit apothecary sold preparations of bezoar stones. The human bezoars may be formed by non-digestible material like cellulose (phytobezoar), hair (trichobezoar), conglomerations of medications or his vehicles (pharmacobezoar or medication bezoar), milk and mucus component (lactobezoar) or other varieties of substances. This condition may be asymptomatic or can produce abdominal pain, ulceration, gastrointestinal bleeding, gastric outlet obstruction, perforation and mechanical intestinal obstruction. We report their classification, diagnostic modalities and treatment.

  3. The acceleration of energetic particles in the interplanetary medium by transit-time damping

    NASA Technical Reports Server (NTRS)

    Fisk, L. A.

    1976-01-01

    Transit time damping is examined as a possible means for accelerating low energy particles in co-rotating streams and interstellar ions. Data show that: the protons in co-rotating streams may be accelerated by transient-time damping the small-scale variations in the field magnitude that are observed at a low level in the inner solar system. The interstellar ions may be accelerated by transit time damping large-scale field variations in the outer solar system.

  4. Time-Varying Transition Probability Matrix Estimation and Its Application to Brand Share Analysis.

    PubMed

    Chiba, Tomoaki; Hino, Hideitsu; Akaho, Shotaro; Murata, Noboru

    2017-01-01

    In a product market or stock market, different products or stocks compete for the same consumers or purchasers. We propose a method to estimate the time-varying transition matrix of the product share using a multivariate time series of the product share. The method is based on the assumption that each of the observed time series of shares is a stationary distribution of the underlying Markov processes characterized by transition probability matrices. We estimate transition probability matrices for every observation under natural assumptions. We demonstrate, on a real-world dataset of the share of automobiles, that the proposed method can find intrinsic transition of shares. The resulting transition matrices reveal interesting phenomena, for example, the change in flows between TOYOTA group and GM group for the fiscal year where TOYOTA group's sales beat GM's sales, which is a reasonable scenario.

  5. Time-Varying Transition Probability Matrix Estimation and Its Application to Brand Share Analysis

    PubMed Central

    Chiba, Tomoaki; Akaho, Shotaro; Murata, Noboru

    2017-01-01

    In a product market or stock market, different products or stocks compete for the same consumers or purchasers. We propose a method to estimate the time-varying transition matrix of the product share using a multivariate time series of the product share. The method is based on the assumption that each of the observed time series of shares is a stationary distribution of the underlying Markov processes characterized by transition probability matrices. We estimate transition probability matrices for every observation under natural assumptions. We demonstrate, on a real-world dataset of the share of automobiles, that the proposed method can find intrinsic transition of shares. The resulting transition matrices reveal interesting phenomena, for example, the change in flows between TOYOTA group and GM group for the fiscal year where TOYOTA group’s sales beat GM’s sales, which is a reasonable scenario. PMID:28076383

  6. Deriving the time-variant transit time distributions of an Austrian karst system by a semi-distributed karst model

    NASA Astrophysics Data System (ADS)

    Hartmann, Andreas; Kobler, Johannes; Kralik, Martin; Dirnboeck, Thomas; Humer, Franko; Weiler, Markus

    2014-05-01

    Karst systems contribute around 50% to Austria's drinking water supply. Distributions of transit times of water and hence other water quality parameters can be highly valuable when assessing the risk of contamination of a karst aquifer. In this study we assess the transit time distributions of a dolomite karst system in Austria. Using a new type of semi-distributed model that considers the spatial heterogeneity of the karst system by distribution functions we simulated a range of spatially variable pathways through the karst system. To assure a reliable calibration of the model we used observations of discharge at 2 different locations and 3 time series of solute concentrations (DOC, NO3 and SO4). We benchmarked the model with a split sample test using all 5 types of observations. Having enough indication for a realistic representation of the system and its flow and storage behaviour, the range of simulated pathways through the karst system was used to derive transit time distributions for different initial conditions. We use experimentally derived information about transit times (water ages, O 18 observations, tracer experiments) to evaluate the simulated residence time distributions. Finally, the process-based structure of the model allows to attribute the different transit time distributions to physical processes and pathways in the karst system and to assess the system's vulnerability on contamination.

  7. Supporting Students in Military Families during Times of Transition: A Call for Awareness and Action

    ERIC Educational Resources Information Center

    Cole, Rebekah F.

    2016-01-01

    Throughout their time in school, students in military families face many challenging periods of transition, which include deployments, relocations, and the family's separation from the military. During these transitions, students in military families may be especially susceptible to social, emotional, and academic challenges both in their home…

  8. Psychosocial Adversities and Timing of Adolescent Transitions: A Comparison of the Former East and West Germanies.

    ERIC Educational Resources Information Center

    Silbereisen, Rainer K.; And Others

    This study was conducted to examine the timing of adolescent transitions. Its first aim was to investigate the hypothesis that cumulated family adversities during childhood would predict earlier transitions in domains such as behavioral autonomy and friendship formation during adolescence. Subjects (N=1,631) were adolescents between the ages of 13…

  9. Supporting Students in Military Families during Times of Transition: A Call for Awareness and Action

    ERIC Educational Resources Information Center

    Cole, Rebekah F.

    2017-01-01

    Throughout their time in school, students in military families face many challenging periods of transition, which include deployments, relocations, and the family's separation from the military. During these transitions, students in military families may be especially susceptible to social, emotional, and academic challenges both in their home…

  10. Tests of correlation between immediate postoperative gastroduodenal transit times and weight loss after laparoscopic sleeve gastrectomy.

    PubMed

    Parikh, Manish; Eisner, Joseph; Hindman, Nicole; Balthazar, Emil; Saunders, John K

    2012-12-01

    Previous studies have shown accelerated gastric emptying after sleeve gastrectomy. This study aimed to determine whether a correlation exists between immediate postoperative gastroduodenal transit time and weight loss after laparoscopic sleeve gastrectomy (LSG). Specifically, correlation tests were conducted to determine whether more rapid transit after LSG correlated with increased weight loss. Data were collected from an institutional review board-approved electronic registry. All LSGs were performed over a 40-Fr bougie, starting 5 to 7 cm proximal to the pylorus. Gastroduodenal transit time (antrum to duodenum) was calculated from a postoperative day 1 esophagram. Pearson's correlation coefficient was used for statistical analysis. The analysis included 62 consecutive LSG patients. The mean gastroduodenal transit time was 12.3 ± 19.8 s. Almost all the patients (99%) had a transit time less than 60 s. The mean percentage of excess weight loss (%EWL) was 23.8 ± 9.8% at 3 months, 37.9 ± 11.8% at 6 months, and 52.2 ± 10.8% at 12 months. No correlation was found between gastroduodenal transit time and %EWL at 3, 6, or 12 months. No correlation was found between gastroduodenal transit time and weight loss after LSG.

  11. An efficient tracer experimental design for measuring time-variable transit time distributions in periodic hydrodynamic systems

    NASA Astrophysics Data System (ADS)

    Harman, Ciaran; Kim, Minseok

    2014-05-01

    The time-varying transport dynamics of complex hydrodynamic systems with long transit times are difficult to observe even in experimental systems due to the need for multiple tracer injections. Where only one or two distinct tracers are available, overprinting in the output concentrations limits the injection frequency. We will present an experimental method (the PERiodic Tracer Hierarchy - PERTH) that allows overprinted breakthrough curves to be decomposed into contributions from multiple injections of the same tracer, so long as the transporting flow is periodic. This method allows the time varying transit time distributions to be observed efficiently while making no a priori assumptions about the transport processes operating in the system. Simulations of transport through a soil column subject to a periodic sequence of irrigation events demonstrate that the distinct transit time distributions associated with each irrigation event can be retrieved almost exactly.

  12. Critical capacity, travel time delays and travel time distribution of rapid mass transit systems

    NASA Astrophysics Data System (ADS)

    Legara, Erika Fille; Monterola, Christopher; Lee, Kee Khoon; Hung, Gih Guang

    2014-07-01

    We set up a mechanistic agent-based model of a rapid mass transit system. Using empirical data from Singapore's unidentifiable smart fare card, we validate our model by reconstructing actual travel demand and duration of travel statistics. We subsequently use this model to investigate two phenomena that are known to significantly affect the dynamics within the RTS: (1) overloading in trains and (2) overcrowding in the RTS platform. We demonstrate that by varying the loading capacity of trains, a tipping point emerges at which an exponential increase in the duration of travel time delays is observed. We also probe the impact on the rail system dynamics of three types of passenger growth distribution across stations: (i) Dirac delta, (ii) uniform and (iii) geometric, which is reminiscent of the effect of land use on transport. Under the assumption of a fixed loading capacity, we demonstrate the dependence of a given origin-destination (OD) pair on the flow volume of commuters in station platforms.

  13. The use of content and timing to predict turn transitions.

    PubMed

    Garrod, Simon; Pickering, Martin J

    2015-01-01

    For addressees to respond in a timely fashion, they cannot simply process the speaker's utterance as it occurs and wait till it finishes. Instead, they predict both when the speaker will conclude and what linguistic forms will be used. While doing this, they must also prepare their own response. To explain this, we draw on the account proposed by Pickering and Garrod (2013a), in which addressees covertly imitate the speaker's utterance and use this to determine the intention that underlies their upcoming utterance. They use this intention to predict when and how the utterance will end, and also to drive their own production mechanisms for preparing their response. Following Arnal and Giraud (2012), we distinguish between mechanisms that predict timing and content. In particular, we propose that the timing mechanism relies on entrainment of low-frequency oscillations between speech envelope and brain. This constrains the context that feeds into the determination of the speaker's intention and hence the timing and form of the upcoming utterance. This approach typically leads to well-timed contributions, but also provides a mechanism for resolving conflicts, for example when there is unintended speaker overlap.

  14. The use of content and timing to predict turn transitions

    PubMed Central

    Garrod, Simon; Pickering, Martin J.

    2015-01-01

    For addressees to respond in a timely fashion, they cannot simply process the speaker's utterance as it occurs and wait till it finishes. Instead, they predict both when the speaker will conclude and what linguistic forms will be used. While doing this, they must also prepare their own response. To explain this, we draw on the account proposed by Pickering and Garrod (2013a), in which addressees covertly imitate the speaker's utterance and use this to determine the intention that underlies their upcoming utterance. They use this intention to predict when and how the utterance will end, and also to drive their own production mechanisms for preparing their response. Following Arnal and Giraud (2012), we distinguish between mechanisms that predict timing and content. In particular, we propose that the timing mechanism relies on entrainment of low-frequency oscillations between speech envelope and brain. This constrains the context that feeds into the determination of the speaker's intention and hence the timing and form of the upcoming utterance. This approach typically leads to well-timed contributions, but also provides a mechanism for resolving conflicts, for example when there is unintended speaker overlap. PMID:26124728

  15. First-time viewers' comprehension of films: bridging shot transitions.

    PubMed

    Ildirar, Sermin; Schwan, Stephan

    2015-02-01

    Which perceptual and cognitive prerequisites must be met in order to be able to comprehend a film is still unresolved and a controversial issue. In order to gain some insights into this issue, our field experiment investigates how first-time adult viewers extract and integrate meaningful information across film cuts. Three major types of commonalities between adjacent shots were differentiated, which may help first-time viewers with bridging the shots: pictorial, causal, and conceptual. Twenty first-time, 20 low-experienced and 20 high-experienced viewers from Turkey were shown a set of short film clips containing these three kinds of commonalities. Film clips conformed also to the principles of continuity editing. Analyses of viewers' spontaneous interpretations show that first-time viewers indeed are able to notice basic pictorial (object identity), causal (chains of activity), as well as conceptual (links between gaze direction and object attention) commonalities between shots due to their close relationship with everyday perception and cognition. However, first-time viewers' comprehension of the commonalities is to a large degree fragile, indicating the lack of a basic notion of what constitutes a film.

  16. Using a physically-based transit time distribution function to estimate the hydraulic parameters and hydraulic transit times of an unconfined aquifer from tritium measurements

    NASA Astrophysics Data System (ADS)

    Farlin, Julien; Maloszewski, Piotr; Schneider, Wilfried; Gallé, Tom

    2014-05-01

    Groundwater transit time is of interest in environmental studies pertaining to the transport of pollutants from its source to the aquifer outlet (spring or pumping well) or to an observation well. Different models have been proposed to describe the distribution of transit times within groundwatersheds, the most common being the dispersion model, the exponential-piston-flow model (EPM) both proposed by Maloszewski and Zuber (Maloszewski and Zuber, 1982) and the (two or three parameter) gamma model (Amin and Campana, 1996; Kirchner et al., 1999). Choosing which function applies best is a recurrent and controversial problem in hydrogeology. The object of this study is to revisit the applicability of the EPM for unconfined aquifers, and to introduce an alternative model based explicitly on groundwater hydraulics. The alternative model is based on the transit time of water from any point at the groundwater table to the aquifer outlet, and is used to calculate inversely the hydraulic parameters of a fractured unconfined sandstone aquifer from tritium measurements made in a series of contact springs. This model is compared to the EPM, which is usually adopted to describe the transit time distribution of confined and unconfined aquifers alike. Both models are tested against observations, and it is shown that the EPM fails the test for some of the springs, and generally seems to overestimate the older water component. Amin, I. E., and M. E. Campana (1996), A general lumped parameter model for the interpretation of tracer data and transit time calculation in hydrologic systems, Journal of Hydrology, 179, 1-21, doi: 10.1016/0022-1694(95)02880-3. Kirchner, J. W., X. H. Feng, and C. Neal (1999), Fractal stream chemistry and its implications for contaminant transport in catchments, Nature physics, 403, 524-527, doi: 10.1038/35000537. Maloszewski, P., and A. Zuber (1982), Determining the turnover time of groundwater systems with the aid of environmental tracers, Journal of

  17. TTVFast: An Efficient and Accurate Code for Transit Timing Inversion Problems

    NASA Astrophysics Data System (ADS)

    Deck, Katherine M.; Agol, Eric; Holman, Matthew J.; Nesvorný, David

    2014-06-01

    Transit timing variations (TTVs) have proven to be a powerful technique for confirming Kepler planet candidates, for detecting non-transiting planets, and for constraining the masses and orbital elements of multi-planet systems. These TTV applications often require the numerical integration of orbits for computation of transit times (as well as impact parameters and durations); frequently tens of millions to billions of simulations are required when running statistical analyses of the planetary system properties. We have created a fast code for transit timing computation, TTVFast, which uses a symplectic integrator with a Keplerian interpolator for the calculation of transit times. The speed comes at the expense of accuracy in the calculated times, but the accuracy lost is largely unnecessary, as transit times do not need to be calculated to accuracies significantly smaller than the measurement uncertainties on the times. The time step can be tuned to give sufficient precision for any particular system. We find a speed-up of at least an order of magnitude relative to dynamical integrations with high precision using a Bulirsch-Stoer integrator.

  18. TTVFast: An efficient and accurate code for transit timing inversion problems

    SciTech Connect

    Deck, Katherine M.; Agol, Eric; Holman, Matthew J.; Nesvorný, David

    2014-06-01

    Transit timing variations (TTVs) have proven to be a powerful technique for confirming Kepler planet candidates, for detecting non-transiting planets, and for constraining the masses and orbital elements of multi-planet systems. These TTV applications often require the numerical integration of orbits for computation of transit times (as well as impact parameters and durations); frequently tens of millions to billions of simulations are required when running statistical analyses of the planetary system properties. We have created a fast code for transit timing computation, TTVFast, which uses a symplectic integrator with a Keplerian interpolator for the calculation of transit times. The speed comes at the expense of accuracy in the calculated times, but the accuracy lost is largely unnecessary, as transit times do not need to be calculated to accuracies significantly smaller than the measurement uncertainties on the times. The time step can be tuned to give sufficient precision for any particular system. We find a speed-up of at least an order of magnitude relative to dynamical integrations with high precision using a Bulirsch-Stoer integrator.

  19. Methods for Detecting Early Warnings of Critical Transitions in Time Series Illustrated Using Simulated Ecological Data

    PubMed Central

    Dakos, Vasilis; Carpenter, Stephen R.; Brock, William A.; Ellison, Aaron M.; Guttal, Vishwesha; Ives, Anthony R.; Kéfi, Sonia; Livina, Valerie; Seekell, David A.; van Nes, Egbert H.; Scheffer, Marten

    2012-01-01

    Many dynamical systems, including lakes, organisms, ocean circulation patterns, or financial markets, are now thought to have tipping points where critical transitions to a contrasting state can happen. Because critical transitions can occur unexpectedly and are difficult to manage, there is a need for methods that can be used to identify when a critical transition is approaching. Recent theory shows that we can identify the proximity of a system to a critical transition using a variety of so-called ‘early warning signals’, and successful empirical examples suggest a potential for practical applicability. However, while the range of proposed methods for predicting critical transitions is rapidly expanding, opinions on their practical use differ widely, and there is no comparative study that tests the limitations of the different methods to identify approaching critical transitions using time-series data. Here, we summarize a range of currently available early warning methods and apply them to two simulated time series that are typical of systems undergoing a critical transition. In addition to a methodological guide, our work offers a practical toolbox that may be used in a wide range of fields to help detect early warning signals of critical transitions in time series data. PMID:22815897

  20. FAST INVERSION METHOD FOR DETERMINATION OF PLANETARY PARAMETERS FROM TRANSIT TIMING VARIATIONS

    SciTech Connect

    Nesvorny, David; Beauge, Cristian

    2010-01-20

    The transit timing variation (TTV) method relies on monitoring changes in timing of transits of known exoplanets. Non-transiting planets in the system can be inferred from TTVs by their gravitational interaction with the transiting planet. The TTV method is sensitive to low-mass planets that cannot be detected by other means. Here we describe a fast algorithm that can be used to determine the mass and orbit of the non-transiting planets from the TTV data. We apply our code, ttvim.f, to a wide variety of planetary systems to test the uniqueness of the TTV inversion problem and its dependence on the precision of TTV observations. We find that planetary parameters, including the mass and mutual orbital inclination of planets, can be determined from the TTV data sets that should become available in near future. Unlike the radial velocity technique, the TTV method can therefore be used to characterize the inclination distribution of multi-planet systems.

  1. Daytime sleepiness during transition into daylight saving time in adolescents: Are owls higher at risk?

    PubMed

    Schneider, Anne-Marie; Randler, Christoph

    2009-10-01

    Individuals differ in their biological rhythms and preferences for time of day. Here, we looked at the transition into daylight saving time (DST) in adolescents. As adolescents tend to be evening types, one may expect that they suffer from a transition into DST. To assess these changes, we measured daytime sleepiness and morningness-eveningness preference (CSM score) in adolescents. Daytime sleepiness correlated with age and CSM score. Older pupils and evening types showed a higher sleepiness. Daytime sleepiness was higher after the transition until the third week after. Older pupils and pupils scoring higher on eveningness reported higher daytime sleepiness after the transition, suggesting that these pupils suffer most from the change. Using cut-off scores for larks and owls, we found that owls showed higher sleepiness than larks. As one consequence, class and school performance tests should not take place in the first week(s) after the transition into DST.

  2. Control analysis of transit time for free and enzyme-bound metabolites: physiological and evolutionary significance of metabolic response times.

    PubMed Central

    Cascante, M; Meléndez-Hevia, E; Kholodenko, B; Sicilia, J; Kacser, H

    1995-01-01

    Control analysis of transit time, defined as tau = delta/J, has previously been considered with the constraint of low enzyme concentrations compared with free pools of metabolites [Meléndez-Hevia, Torres, Sicilia and Kacser (1990) Biochem. J. 265, 195-202]. One of the conclusions was that the sum of the control coefficients of the transition time with respect to enzyme concentration was -1. Here we demonstrate that, if the enzyme-bound pools are taken into consideration (which would be important at high enzyme concentrations and high affinities), the sum lies between 0 and -1. The transition time between two steady states, which are frequent physiological events, is mainly governed by time constants involved in changing the enzyme concentrations. Some physiological and evolutionary aspects are discussed. PMID:8948448

  3. Studies in Transition and Time Varying Turbulent Flows

    NASA Technical Reports Server (NTRS)

    Grosch, Chester E.

    2004-01-01

    The research focused on two areas: (a) the dynamics of forced turbulent flows and (b) time filtered Large Eddy Simulations (TLES). The dynamics of turbulent flows arising from external forcing of the turbulence are poorly understood. In particular, here are many unanswered questions relating the basic dynamical balances and the existence or nonexistence of statistical equilibrium of forced turbulent flows. The research used direct numerical simulations to explore these questions. The properties of the temporally filtered Navier-Stokes equations were also studied.

  4. Scintigraphic determination of small intestinal transit time: Comparison with the hydrogen breath technique

    SciTech Connect

    Caride, V.J.; Prokop, E.K.; Troncale, F.J.; Buddoura, W.; Winchenbach, K.; McCallum, R.W.

    1984-04-01

    The hydrogen breath test was used as a standard against which a scintigraphic method for determination of small intestinal transit time was evaluated and compared. A total of 19 male volunteers ranging in age from 23 to 28 yr participated in the study. The subjects ingested an isosmotic lactulose solution containing /sup 99m/technetium-diethylenetriaminepentaacetic acid (Sn) and then remained supine under a large field of view gamma-camera that interfaced with a computer system. Data were visually analyzed and then quantified to determine gastric emptying and small intestinal transit time. The small intestinal transit time ranged from 31 to 139 min with the scintigraphic method and 30 to 190 min with the hydrogen breath test (r . 0.77). The mean small intestinal transit time for 20 individual determinations with the scintigraphic method, 73.0 +/- 6.5 min (mean +/- SEM), was similar to the results from the hydrogen breath test technique, 75.1 +/- 8.3 min. Thirteen volunteers underwent two studies with the scintigraphic method separated by intervals ranging from 2 days to 8 wk. Individual variations in small intestinal transit time were significantly correlated with individual variations in gastric emptying (p less than 0.05). We conclude that the scintigraphic method allows accurate determination of gastrocecal time and is a noninvasive technique which may be a useful clinical test for small intestinal transit time as well as for providing information on the pathophysiology and pharmacology of intestinal motility.

  5. Using Dielectric Relaxation Spectroscopy to Characterize the Glass Transition Time of Polydextrose.

    PubMed

    Buehler, Martin G; Kindle, Michael L; Carter, Brady P

    2015-06-01

    Dielectric relaxation spectroscopy was used to characterize the glass transition time, tg , of polydextrose, where the glass transition temperature, Tg , and water activity, aw (relative humidity), were held constant during polydextrose relaxation. The tg was determined from a shift in the peak frequency of the imaginary capacitance spectrum with time. It was found that when the peak frequency reaches 30 mHz, polydextrose undergoes glass transition. Glass transition time, tg , is the time for polydextrose to undergo glass transition at a specific Tg and aw . Results lead to a modified state diagram, where Tg is depressed with increasing aw . This curve forms a boundary: (a) below the boundary, polydextrose does not undergo glass transition and (b) above the boundary, polydextrose rapidly undergoes glass transition. As the boundary curve is specified by a tg value, it can assist in the selection of storage conditions. An important point on the boundary curve is at aw = 0, where Tg0 = 115 °C. The methodology can also be used to calculate the stress-relaxation viscosity of polydextrose as a function of Tg and aw , which is important when characterizing the flow properties of polydextrose initially in powder form.

  6. Transit Timing Observations from Kepler: VII. Potentially interesting candidate systems from Fourier-based statistical tests

    SciTech Connect

    Steffen, Jason H.; Ford, Eric B.; Rowe, Jason F.; Fabrycky, Daniel C.; Holman, Matthew J.; Welsh, William F.; Borucki, William J.; Batalha, Natalie M.; Bryson, Steve; Caldwell, Douglas A.; Ciardi, David R.; /Caltech /NASA, Ames /SETI Inst., Mtn. View

    2012-01-01

    We analyze the deviations of transit times from a linear ephemeris for the Kepler Objects of Interest (KOI) through Quarter six (Q6) of science data. We conduct two statistical tests for all KOIs and a related statistical test for all pairs of KOIs in multi-transiting systems. These tests identify several systems which show potentially interesting transit timing variations (TTVs). Strong TTV systems have been valuable for the confirmation of planets and their mass measurements. Many of the systems identified in this study should prove fruitful for detailed TTV studies.

  7. VizieR Online Data Catalog: 4 Kepler systems transit timing observations (Steffen+, 2012)

    NASA Astrophysics Data System (ADS)

    Steffen, J. H.; Fabrycky, D. C.; Ford, E. B.; Carter, J. A.; Desert, J.-M.; Fressin, F.; Holman, M. J.; Lissauer, J. J.; Moorhead, A. V.; Rowe, J. F.; Ragozzine, D.; Welsh, W. F.; Batalha, N. M.; Borucki, W. J.; Buchhave, L. A.; Bryson, S.; Caldwell, D. A.; Charbonneau, D.; Ciardi, D. R.; Cochran, W. D.; Endl, M.; Everett, M. E.; Gautier, T. N., III; Gilliland, R. L.; Girouard, F. R.; Jenkins, J. M.; Horch, E.; Howell, S. B.; Isaacson, H.; Klaus, T. C.; Koch, D. G.; Latham, D. W.; Li, J.; Lucas, P.; MacQueen, P. J.; Marcy, G. W.; McCauliff, S.; Middour, C. K.; Morris, R. L.; Mullally, F. R.; Quinn, S. N.; Quintana, E. V.; Shporer, A.; Still, M.; Tenenbaum, P.; Thompson, S. E.; Twicken, J. D.; van Cleve, J.

    2013-03-01

    We present a method to confirm the planetary nature of objects in systems with multiple transiting exoplanet candidates. This method involves a Fourier-domain analysis of the deviations in the transit times from a constant period that result from dynamical interactions within the system. The combination of observed anticorrelations in the transit times and mass constraints from dynamical stability allow us to claim the discovery of four planetary systems, Kepler-25, Kepler-26, Kepler-27 and Kepler-28, containing eight planets and one additional planet candidate. (4 data files).

  8. TRANSIT TIMING OBSERVATIONS FROM KEPLER. VI. POTENTIALLY INTERESTING CANDIDATE SYSTEMS FROM FOURIER-BASED STATISTICAL TESTS

    SciTech Connect

    Steffen, Jason H.; Ford, Eric B.; Rowe, Jason F.; Borucki, William J.; Bryson, Steve; Caldwell, Douglas A.; Jenkins, Jon M.; Koch, David G.; Sanderfer, Dwight T.; Seader, Shawn; Twicken, Joseph D.; Fabrycky, Daniel C.; Welsh, William F.; Batalha, Natalie M.; Ciardi, David R.; Prsa, Andrej

    2012-09-10

    We analyze the deviations of transit times from a linear ephemeris for the Kepler Objects of Interest (KOI) through quarter six of science data. We conduct two statistical tests for all KOIs and a related statistical test for all pairs of KOIs in multi-transiting systems. These tests identify several systems which show potentially interesting transit timing variations (TTVs). Strong TTV systems have been valuable for the confirmation of planets and their mass measurements. Many of the systems identified in this study should prove fruitful for detailed TTV studies.

  9. [Value of the palliative prognostic index, controlling nutritional status, and prognostic nutritional index for objective evaluation during transition from chemotherapy to palliative care in cases of advanced or recurrent gastrointestinal cancer].

    PubMed

    Fukushima, Tsuyoshi; Annen, Kazuya; Kawamukai, Yuji; Onuma, Noritomo; Kawashima, Mayu

    2014-07-01

    We investigated whether objective evaluation by using the palliative prognostic index(PPI), controlling nutritional status(COUNT), and prognostic nutritional index(PNI)can provide prognostic information during the transition from chemotherapy to palliative care in patients with advanced or recurrent gastrointestinal cancer. The subjects were 28 patients with gastrointestinal cancer who died of their disease between January 2009 and June 2012. We compared the PPI, COUNT, and PNI scores between patients who died within 90 days of completing chemotherapy(Group A, n=14)and patients who survived for 90 or more days(Group B, n=14). The PPI score for Group A(4.0)was significantly higher than that for Group B(0.8)(p<0.001). The COUNT score was also significantly higher for Group A(6.3)than for Group B (3.9)(p=0.033). A significant difference in survival was evident when the cutoff value for PNI was set at 40 in the critical region(68/118, p=0.04). Our study suggests that the PPI, COUNT, and PNI may be useful for objective evaluation during the transition from chemotherapy to palliative care.

  10. Scintigraphic Small Intestinal Transit Time and Defaecography in Patients with J-Pouch

    PubMed Central

    Kjaer, Mie Dilling; Simonsen, Jane Angel; Hvidsten, Svend; Kjeldsen, Jens; Gerke, Oke; Qvist, Niels

    2015-01-01

    Objective methods for examination of pouch function are warranted for a better understanding of the functional result and treatment of dysfunction. The objective of this study was to evaluate the results of scintigraphic intestinal transit time and defaecography compared to the results of pouch function, mucosal condition and a questionnaire on quality of life (QoL). This cross-sectional study included 21 patients. Scintigraphic transit time and defaecography was determined with the use of Tc-99m. Pouch function was assessed by number of bowel movements, pouch volume, and continence. Pouch mucosal condition was evaluated by endoscopy and histology. Median transit time was 189 min (105–365). Median ejection fraction at defaecography (EF) was 49% (3–77) and 62% (17–98) after first and second defecation. Median pouch volume was 223 mL (100–360). A median daily stool frequency of nine (4–25) was reported and three (14%) patients suffered from daytime incontinence. No patients had symptomatic or endoscopic pouchitis; however, the histology showed unspecific inflammation in 19 (90%) patients. There was no correlation between transit time, evacuation fraction (EF) and pouch function in univariate analysis. However, we found a high body mass index (BMI) and a low bowel movement frequency to be associated with a longer transit time by multivariate analysis. Scintigraphic determination of transit time and defaecography are feasible methods in patients with ileal pouch anal anastomosis, but the clinical relevance is yet doubtful. PMID:26854162

  11. Effects of alpha-glucosidase inhibitors on mouth to caecum transit time in humans.

    PubMed

    Ladas, S D; Frydas, A; Papadopoulos, A; Raptis, S A

    1992-09-01

    The alpha-glucosidase inhibitors acarbose and miglitol have been successfully used to control postprandial hyperglycaemia in diabetics. They probably work by slowing carbohydrate digestion and absorption, but their effect on mouth to caecum transit time has not been studied. The effect acarbose (100 mg), miglitol (100 mg), and placebo on mouth to caecum transit time (380 kcal breakfast with 20 g of lactulose) was investigated in 18 normal volunteers using breath hydrogen analysis. Both miglitol and acarbose significantly increased breath hydrogen excretion (F2,34 = 6.31, p = 0.005) and shortened the mouth to caecum transit time (F2,34 = 3.49, p = 0.04) after breakfast compared with placebo. There was a significant negative correlation between breath hydrogen excretion and mouth to caecum transit time suggesting that with shorter transit times significantly more carbohydrates were spilled into the colon. These results indicate that alpha-glucosidase inhibitors accelerate mouth to caecum transit time by inducing carbohydrate malabsorption.

  12. Scintigraphic Small Intestinal Transit Time and Defaecography in Patients with J-Pouch.

    PubMed

    Kjaer, Mie Dilling; Simonsen, Jane Angel; Hvidsten, Svend; Kjeldsen, Jens; Gerke, Oke; Qvist, Niels

    2015-10-10

    Objective methods for examination of pouch function are warranted for a better understanding of the functional result and treatment of dysfunction. The objective of this study was to evaluate the results of scintigraphic intestinal transit time and defaecography compared to the results of pouch function, mucosal condition and a questionnaire on quality of life (QoL). This cross-sectional study included 21 patients. Scintigraphic transit time and defaecography was determined with the use of Tc-99m. Pouch function was assessed by number of bowel movements, pouch volume, and continence. Pouch mucosal condition was evaluated by endoscopy and histology. Median transit time was 189 min (105-365). Median ejection fraction at defaecography (EF) was 49% (3-77) and 62% (17-98) after first and second defecation. Median pouch volume was 223 mL (100-360). A median daily stool frequency of nine (4-25) was reported and three (14%) patients suffered from daytime incontinence. No patients had symptomatic or endoscopic pouchitis; however, the histology showed unspecific inflammation in 19 (90%) patients. There was no correlation between transit time, evacuation fraction (EF) and pouch function in univariate analysis. However, we found a high body mass index (BMI) and a low bowel movement frequency to be associated with a longer transit time by multivariate analysis. Scintigraphic determination of transit time and defaecography are feasible methods in patients with ileal pouch anal anastomosis, but the clinical relevance is yet doubtful.

  13. Transition path times reveal memory effects and anomalous diffusion in the dynamics of protein folding

    NASA Astrophysics Data System (ADS)

    Satija, Rohit; Das, Atanu; Makarov, Dmitrii E.

    2017-10-01

    Recent single-molecule experiments probed transition paths of biomolecular folding and, in particular, measured the time biomolecules spend while crossing their free energy barriers. A surprising finding from these studies is that the transition barriers crossed by transition paths, as inferred from experimentally observed transition path times, are often lower than the independently determined free energy barriers. Here we explore memory effects leading to anomalous diffusion as a possible origin of this discrepancy. Our analysis of several molecular dynamics trajectories shows that the dynamics of common reaction coordinates used to describe protein folding is subdiffusive, at least at sufficiently short times. We capture this effect using a one-dimensional fractional Brownian motion (FBM) model, in which the system undergoes a subdiffusive process in the presence of a potential of mean force, and show that this model yields much broader distributions of transition path times with stretched exponential long-time tails. Without any adjustable parameters, these distributions agree well with the transition path times computed directly from protein trajectories. We further discuss how the FBM model can be tested experimentally.

  14. Gastrointestinal clinical pharmacology of peppermint oil.

    PubMed

    Grigoleit, H G; Grigoleit, P

    2005-08-01

    In nine studies, 269 healthy subjects or patients underwent exposure to peppermint oil (PO) either by topical intraluminal (stomach or colon) or oral administration by single doses or 2 weeks treatment (n = 19). Methods used to detect effects were oro-cecal transit time by hydrogen expiration, total gastrointestinal transit time by carmine red method, gastric emptying time by radiolabelled test meal or sonography, direct observation of colonic motility or indirect recording through pressure changes or relieve of colonic spasms during barium enema examination. The dose range covered in single dose studies is 0.1-0.24ml of PO/subject. With one exception, which show an unexplained potentiation of neostigmine stimulated colon activity, all other studies result in effects, indicating a substantial spasmolytic effect of PO of the smooth muscles of the gastrointestinal tract. Pharmacokinetic studies reveal that fractionated urinary recovery of menthol is dependent on the kind of formulation used for the application of PO. Optimal pH triggered enteric coated formulations start releasing PO in the small intestine extending release over 10-12 h thus providing PO to the target organ in irritable bowel syndrome, i.e. the colon. The hypothesis is supported by anecdotal observations in patients with achlorhydria or ileostoma, respectively.

  15. Transition.

    ERIC Educational Resources Information Center

    Thompson, Sandy, Ed.; And Others

    1990-01-01

    This "feature issue" focuses on transition from school to adult life for persons with disabilities. Included are "success stories," brief program descriptions, and a list of resources. Individual articles include the following titles and authors: "Transition: An Energizing Concept" (Paul Bates); "Transition…

  16. TRANSIT TIMING OBSERVATIONS FROM KEPLER. I. STATISTICAL ANALYSIS OF THE FIRST FOUR MONTHS

    SciTech Connect

    Ford, Eric B.; Rowe, Jason F.; Caldwell, Douglas A.; Jenkins, Jon M.; Li Jie; Fabrycky, Daniel C.; Lissauer, Jack J.; Borucki, William J.; Bryson, Steve; Koch, David G.; Steffen, Jason H.; Batalha, Natalie M.; Dunham, Edward W.; Gautier, Thomas N.; Marcy, Geoffrey W.; McCauliff, Sean

    2011-11-01

    The architectures of multiple planet systems can provide valuable constraints on models of planet formation, including orbital migration, and excitation of orbital eccentricities and inclinations. NASA's Kepler mission has identified 1235 transiting planet candidates. The method of transit timing variations (TTVs) has already confirmed seven planets in two planetary systems. We perform a transit timing analysis of the Kepler planet candidates. We find that at least {approx}11% of planet candidates currently suitable for TTV analysis show evidence suggestive of TTVs, representing at least {approx}65 TTV candidates. In all cases, the time span of observations must increase for TTVs to provide strong constraints on planet masses and/or orbits, as expected based on N-body integrations of multiple transiting planet candidate systems (assuming circular and coplanar orbits). We find the fraction of planet candidates showing TTVs in this data set does not vary significantly with the number of transiting planet candidates per star, suggesting significant mutual inclinations and that many stars with a single transiting planet should host additional non-transiting planets. We anticipate that Kepler could confirm (or reject) at least {approx}12 systems with multiple transiting planet candidates via TTVs. Thus, TTVs will provide a powerful tool for confirming transiting planets and characterizing the orbital dynamics of low-mass planets. If Kepler observations were extended to at least seven years, then TTVs would provide much more precise constraints on the dynamics of systems with multiple transiting planets and would become sensitive to planets with orbital periods extending into the habitable zone of solar-type stars.

  17. Transiting Exoplanet Monitoring Project (TEMP). II. Refined System Parameters and Transit Timing Analysis of HAT-P-33b

    NASA Astrophysics Data System (ADS)

    Wang, Yong-Hao; Wang, Songhu; Liu, Hui-Gen; Hinse, Tobias C.; Laughlin, Gregory; Wu, Dong-Hong; Zhang, Xiaojia; Zhou, Xu; Wu, Zhenyu; Zhou, Ji-Lin; Wittenmyer, R. A.; Eastman, Jason; Zhang, Hui; Hori, Yasunori; Narita, Norio; Chen, Yuanyuan; Ma, Jun; Peng, Xiyan; Zhang, Tian-Meng; Zou, Hu; Nie, Jun-Dan; Zhou, Zhi-Min

    2017-08-01

    We present 10 R-band photometric observations of eight different transits of the hot Jupiter HAT-P-33b, which has been targeted by our Transiting Exoplanet Monitoring Project. The data were obtained by two telescopes at the Xinglong Station of National Astronomical Observatories of China (NAOC) from 2013 December through 2016 January, and exhibit photometric scatter of 1.6{--}3.0 {mmag}. After jointly analyzing the previously published photometric data, radial-velocity (RV) measurements, and our new light curves, we revisit the system parameters and orbital ephemeris for the HAT-P-33b system. Our results are consistent with the published values except for the planet to star radius ratio ({R}{{P}}/{R}* ), the ingress/egress duration (τ) and the total duration (T 14), which together indicate a slightly shallower and shorter transit shape. Our results are based on more complete light curves, whereas the previously published work had only one complete transit light curve. No significant anomalies in Transit Timing Variations (TTVs) are found, and we place upper mass limits on potential perturbers, largely supplanting the loose constraints provided by the extant RV data. The TTV limits are stronger near mean-motion resonances, especially for the low-order commensurabilities. We can exclude the existence of a perturber with mass larger than 0.6, 0.3, 0.5, 0.5, and 0.3 {M}\\oplus near the 1:3, 1:2, 2:3, 3:2, and 2:1 resonances, respectively.

  18. Performance of Real-Time Polymerase Chain Reaction Assays for the Detection of 20 Gastrointestinal Parasites in Clinical Samples from Senegal.

    PubMed

    Sow, Doudou; Parola, Philippe; Sylla, Khadime; Ndiaye, Magatte; Delaunay, Pascal; Halfon, Philippe; Camiade, Sabine; Dieng, Thérèse; Tine, Roger C K; Faye, Babacar; Ndiaye, Jean Louis; Dieng, Yémou; Gaye, Oumar; Raoult, Didier; Bittar, Fadi

    2017-07-01

    Gastrointestinal parasite infections represent one of the biggest public health problems in the world. Therefore, appropriate innovative tools are needed for assessing interventions to control these infections. This study aims to compare the performance of real-time polymerase chain reaction (PCR) assays to microscopic examination for detection of intestinal parasites. A direct microscopic examination and stool concentration was performed on 98 stool samples from patients attending Senegalese hospitals. Negative microscopic control samples were also collected in Nice and Marseille (France). Species-specific primers/probes were used to detect 20 common gastrointestinal protozoans and helminths. Positive frequency and the sensitivity of each real-time PCR assay were compared with conventional microscopic examination. Real-time PCR was positive in 72 of 98 samples (73.5%), whereas microscopic examination was positive in 37 (37.7%) samples (P < 0.001). The real-time PCR assays were more sensitive than microscopy, with 57.4% (31/54) versus 18.5% (10/54), respectively, in the detection of parasites in asymptomatic patients (P < 0.05). In terms of polyparasitism, there were more coinfections detected by real-time PCR assays compared with microscopic methods (25.5% versus 3.06%). In comparison to parasite prevalence on individual samples, the results showed a perfect agreement (100%) between the two techniques for seven species, whereas discrepancies were observed for the others (agreement percentage varying from 64.2% to 98.9%). Real-time PCR appeared to be superior to microscopic examination for the detection of parasites in stool samples. This assay will be useful in diagnostic laboratories and in the field for evaluating the efficacy of mass drug administration programs.

  19. The effect of conjunctions on the transit timing variations of exoplanets

    SciTech Connect

    Nesvorný, David; Vokrouhlický, David E-mail: vokrouhl@cesnet.cz

    2014-07-20

    We develop an analytic model for transit timing variations produced by orbital conjunctions between gravitationally interacting planets. If the planetary orbits have tight orbital spacing, which is a common case among the Kepler planets, the effect of a single conjunction can be best described as: (1) a step-like change of the transit timing ephemeris with subsequent transits of the inner planet being delayed and those of the outer planet being sped up, and (2) a discrete change in sampling of the underlying oscillations from eccentricity-related interaction terms. In the limit of small orbital eccentricities, our analytic model gives explicit equations for these effects as a function of the mass and orbital separation of planets. We point out that a detection of the conjunction effect in real data is of crucial importance for the physical characterization of planetary systems from transit timing variations.

  20. Landau level transitions in doped graphene in a time dependent magnetic field

    NASA Astrophysics Data System (ADS)

    Ardenghi, J. S.; Bechthold, P.; Jasen, P.; Gonzalez, E.; Nagel, O.

    2013-10-01

    The aim of this work is to describe the Landau level transitions of Bloch electrons in doped graphene with an arbitrary time dependent magnetic field in the long wavelength approximation. In particular, transitions from the m Landau level to the m±1 and m±2 Landau levels are studied using the time dependent perturbation theory. Time intervals are computed in which transition probabilities tend to zero at a low order in the coupling constant. In particular, Landau level transitions are studied in the case of Bloch electrons traveling in the direction of the applied magnetic force and the results are compared with classical and revival periods of electrical current in graphene. Finally, current probabilities are computed for the n=0 and n=1 Landau levels showing expected oscillating behavior with modified cyclotron frequency.

  1. A time-dependent order parameter for ultrafast photoinduced phase transitions.

    PubMed

    Beaud, P; Caviezel, A; Mariager, S O; Rettig, L; Ingold, G; Dornes, C; Huang, S-W; Johnson, J A; Radovic, M; Huber, T; Kubacka, T; Ferrer, A; Lemke, H T; Chollet, M; Zhu, D; Glownia, J M; Sikorski, M; Robert, A; Wadati, H; Nakamura, M; Kawasaki, M; Tokura, Y; Johnson, S L; Staub, U

    2014-10-01

    Strongly correlated electron systems often exhibit very strong interactions between structural and electronic degrees of freedom that lead to complex and interesting phase diagrams. For technological applications of these materials it is important to learn how to drive transitions from one phase to another. A key question here is the ultimate speed of such phase transitions, and to understand how a phase transition evolves in the time domain. Here we apply time-resolved X-ray diffraction to directly measure the changes in long-range order during ultrafast melting of the charge and orbitally ordered phase in a perovskite manganite. We find that although the actual change in crystal symmetry associated with this transition occurs over different timescales characteristic of the many electronic and vibrational coordinates of the system, the dynamics of the phase transformation can be well described using a single time-dependent 'order parameter' that depends exclusively on the electronic excitation.

  2. Chronic Obstructive Pulmonary Disease Subtypes. Transitions over Time

    PubMed Central

    Esteban, Cristóbal; Arostegui, Inmaculada; Aburto, Myriam; Moraza, Javier; Quintana, José M.; García-Loizaga, Amaia; Basualdo, Luis V.; Aramburu, Amaia; Aizpiri, Susana; Uranga, Ane; Capelastegui, Alberto

    2016-01-01

    Background Although subtypes of chronic obstructive pulmonary disease are recognized, it is unknown what happens to these subtypes over time. Our objectives were to assess the stability of cluster-based subtypes in patients with stable disease and explore changes in clusters over 1 year. Methods Multiple correspondence and cluster analysis were used to evaluate data collected from 543 stable patients included consecutively from 5 respiratory outpatient clinics. Results Four subtypes were identified. Three of them, A, B, and C, had marked respiratory profiles with a continuum in severity of several variables, while the fourth, subtype D, had a more systemic profile with intermediate respiratory disease severity. Subtype A was associated with less dyspnea, better health-related quality of life and lower Charlson comorbidity scores, and subtype C with the most severe dyspnea, and poorer pulmonary function and quality of life, while subtype B was between subtypes A and C. Subtype D had higher rates of hospitalization the previous year, and comorbidities. After 1 year, all clusters remained stable. Generally, patients continued in the same subtype but 28% migrated to another cluster. Together with movement across clusters, patients showed changes in certain characteristics (especially exercise capacity, some variables of pulmonary function and physical activity) and changes in outcomes (quality of life, hospitalization and mortality) depending on the new cluster they belonged to. Conclusions Chronic obstructive pulmonary disease clusters remained stable over 1 year. Most patients stayed in their initial subtype cluster, but some moved to another subtype and accordingly had different outcomes. PMID:27611911

  3. Timing of the maturation transition in haddock Melanogrammus aeglefinus.

    PubMed

    Tobin, D; Wright, P J; O'Sullivan, M

    2010-10-01

    The timing of maturation in haddock Melanogrammus aeglefinus was examined using changes in gonad development, follicle stimulating hormone β (FSH-β) transcript expression profile, growth and condition of 1 year old females held under a common environment between the summer and winter solstices. The circumnuclear ring, cortical alveolus and vitellogenic oocyte stages were first observed in August, October and November, respectively. FSH-β transcript levels did not change significantly until September but increased markedly thereafter in maturing fish. A combined analysis of the mean oocyte diameter of the leading cohort, histological staging and FSH-β transcript profile provided evidence of a commitment to maturation by October or November. Contrary to that previously proposed for gadoid species, histological analysis of field-caught immature M. aeglefinus during the spawning season indicated that cortical alveolar, rather than circumnuclear ring, stage oocytes provided definitive evidence of maturation. A decrease in relative liver size following the summer solstice suggested a possible link between energy status and maturation.

  4. THE IMPACT OF CIRCUMPLANTARY JETS ON TRANSIT SPECTRA AND TIMING OFFSETS FOR HOT JUPITERS

    SciTech Connect

    Dobbs-Dixon, Ian; Agol, Eric; Burrows, Adam

    2012-06-01

    We present theoretical wavelength-dependent transit light curves for the giant planet HD 209458b based on a number of state-of-the-art three-dimensional radiative hydrodynamical models. By varying the kinematic viscosity in the model, we calculate observable signatures associated with the emergence of a super-rotating circumplanetary jet that strengthens with decreased viscosity. We obtain excellent agreement between our mid-transit transit spectra and existing data from Hubble and Spitzer, finding the best fit for intermediate values of viscosity. We further exploit dynamically driven differences between eastern and western hemispheres to extract the spectral signal imparted by a circumplanetary jet. We predict that (1) the transit depth should decrease as the jet becomes stronger; (2) the measured transit times should show timing offsets of up to 6 s at wavelengths with higher opacity, which increases with jet strength; (3) wavelength-dependent differences between ingress and egress spectra increase with jet strength; and (4) the color-dependent transit shape should exhibit stronger asymmetry for planets with stronger jets. These techniques and trends should be valid for other hot Jupiters as well. Observations of transit timing offsets may be accessible with current instrumentation, though the other predictions may require the capabilities of the James Webb Space Telescope and other future missions. Hydrodynamical models utilized solve the three-dimensional Navier-Stokes equations together with decoupled thermal and radiative energy equations and wavelength-dependent stellar heating.

  5. Transit Timing Variations as a Tool for the Bayesian Characterization of Exoplanets

    NASA Astrophysics Data System (ADS)

    Ford, Eric B.; Jontof-Hutter, Daniel; Dawson, Rebekah; Fabrycky, Daniel; Mills, Sean; Ragozzine, Darin; Rogers, Leslie Anne; Shabram, Megan

    2015-08-01

    NASA's Kepler mission has revolutionized time-domain photometry with its photometric precision, high duty cycle, and long observing baseline. In addition to discovering thousands of planet candidates that pass in front of their host star, Kepler's has enabled the precise measurement of transit timing variations (TTV), deviations of transit times from a Keplerian ephemeris due to gravitational interactions among planets (or more massive bodies in the same planetary system). For dozens of planets, TTVs enable the precise characterization of planet masses and orbits, including many planets for which characterization via Doppler observations is impractical.For example, TTVs have: 1) characterized of masses of planets in systems with 2-6 transiting exoplanets, 2) measured densities for low-mass, low-density mass planets that orbit stars with periods of ~50-200 days, and provided precise measurements of orbital eccentricities even in the challenging regime of e<0.1. In addition to characterizing properties of individual planets, analysing the transit times for populations of transiting planets (including those for which no deviations from Keplerian orbits are detected) enable the characterization of the exoplanet distribution function.In both cases, attention to details of the statistical model and computational methods are essential for drawing robust conclusions. I will present selected TTV success stories, describing how these studies dealt with various statistical and computational challenges. Finally, I will describe opportunities for further improvements in the statistical analyses of transit timing variations and the potential science return.

  6. Daylight saving time transitions and hospital treatments due to accidents or manic episodes

    PubMed Central

    Lahti, Tuuli A; Haukka, Jari; Lönnqvist, Jouko; Partonen, Timo

    2008-01-01

    Background Daylight saving time affects millions of people annually but its impacts are still widely unknown. Sleep deprivation and the change of circadian rhythm can trigger mental illness and cause higher accident rates. Transitions into and out of daylight saving time changes the circadian rhythm and may cause sleep deprivation. Thus it seems plausible that the prevalence of accidents and/or manic episodes may be higher after transition into and out of daylight saving time. The aim of this study was to explore the effects of transitions into and out of daylight saving time on the incidence of accidents and manic episodes in the Finnish population during the years of 1987 to 2003. Methods The nationwide data were derived from the Finnish Hospital Discharge Register. From the register we obtained the information about the hospital-treated accidents and manic episodes during two weeks before and two weeks after the transitions in 1987–2003. Results The results were negative, as the transitions into or out of daylight saving time had no significant effect on the incidence of accidents or manic episodes. Conclusion One-hour transitions do not increase the incidence of manic episodes or accidents which require hospital treatment. PMID:18302734

  7. Daylight saving time transitions and hospital treatments due to accidents or manic episodes.

    PubMed

    Lahti, Tuuli A; Haukka, Jari; Lönnqvist, Jouko; Partonen, Timo

    2008-02-26

    Daylight saving time affects millions of people annually but its impacts are still widely unknown. Sleep deprivation and the change of circadian rhythm can trigger mental illness and cause higher accident rates. Transitions into and out of daylight saving time changes the circadian rhythm and may cause sleep deprivation. Thus it seems plausible that the prevalence of accidents and/or manic episodes may be higher after transition into and out of daylight saving time. The aim of this study was to explore the effects of transitions into and out of daylight saving time on the incidence of accidents and manic episodes in the Finnish population during the years of 1987 to 2003. The nationwide data were derived from the Finnish Hospital Discharge Register. From the register we obtained the information about the hospital-treated accidents and manic episodes during two weeks before and two weeks after the transitions in 1987-2003. The results were negative, as the transitions into or out of daylight saving time had no significant effect on the incidence of accidents or manic episodes. One-hour transitions do not increase the incidence of manic episodes or accidents which require hospital treatment.

  8. Exploring business process modelling paradigms and design-time to run-time transitions

    NASA Astrophysics Data System (ADS)

    Caron, Filip; Vanthienen, Jan

    2016-09-01

    The business process management literature describes a multitude of approaches (e.g. imperative, declarative or event-driven) that each result in a different mix of process flexibility, compliance, effectiveness and efficiency. Although the use of a single approach over the process lifecycle is often assumed, transitions between approaches at different phases in the process lifecycle may also be considered. This article explores several business process strategies by analysing the approaches at different phases in the process lifecycle as well as the various transitions.

  9. Current practice in managing patients on anticoagulants and/or antiplatelet agents around the time of gastrointestinal endoscopy -- a nation-wide survey in Germany.

    PubMed

    Mosler, P; Mergener, K; Denzer, U; Kiesslich, R; Galle, P R; Kanzler, S

    2004-11-01

    Anticoagulants and antiplatelet agents are widely used in the prophylaxis and management of thromboembolic and cardiovascular diseases. Gastrointestinal bleeding is a well-known complication of these agents. Modification of anticoagulant and antiplatelet therapy is often required in patients undergoing surgical procedures and specific recommendations for the perioperative period have been issued. Fewer data exist with regard to the use of these agents around the time of endoscopic procedures. A survey of the American Society for Gastrointestinal Endoscopy (ASGE), performed several years ago, showed a wide variation between endoscopists in the management of anticoagulants and antiplatelet agents in the periendoscopic period. Subsequently, guidelines have been proposed by the ASGE as well as the German Society for Gastroenterology (DGVS). The aim of this study was to investigate the current practices among German endoscopists regarding the use of these medications in patients undergoing endoscopic procedures and to assess their adherence to published guidelines. Our data demonstrate that, in spite of the dissemination of guidelines, there is still a wide variation in the periendoscopic management of patients who are at increased risk for bleeding due to anticoagulants, especially in patients taking antiplatelet agents.

  10. Transit times and age distributions for reservoir models represented as nonlinear non-autonomuous systems

    NASA Astrophysics Data System (ADS)

    Müller, Markus; Meztler, Holger; Glatt, Anna; Sierra, Carlos

    2016-04-01

    We present theoretical methods to compute dynamic residence and transit time distributions for non-autonomous systems of pools governed by coupled nonlinear differential equations. Although transit time and age distributions have been used to describe reservoir models for a long time, a closer look to their assumptions reveals two major restrictions of generality in previous studies. First, the systems are assumed to be in equilibrium; and second, the equations under consideration are assumed to be linear. While both these assumptions greatly ease the computation and interpretation of transit time and age distributions they are not applicable to a wide range of problems. Moreover, the transfer of previous results learned from linear systems in steady state to the more complex nonlinear non-autonomous systems that do not even need to have equilibria, can be dangerously misleading. Fortunately the topic of time dependent age and transit time distributions has received some attention recently in hydrology, we aim to compute these distributions for systems of multiple reservoirs. We will discuss how storage selection functions can augment the information represented in an ODE system describing a system of reservoirs. We will present analytical and numerical algorithms and a Monte Carlo simulator to compute solutions for system transit time and age distributions for system-wide storage selection functions including the most simple, but important case of well mixed pools.

  11. Clozapine-treated Patients Have Marked Gastrointestinal Hypomotility, the Probable Basis of Life-threatening Gastrointestinal Complications: A Cross Sectional Study.

    PubMed

    Every-Palmer, Susanna; Nowitz, Mike; Stanley, James; Grant, Eve; Huthwaite, Mark; Dunn, Helen; Ellis, Pete M

    2016-03-01

    Gastrointestinal side effects are particularly common with clozapine and occur with other antipsychotics, ranging from mild constipation to fatal bowel obstruction and/or ischemia. While this adverse-effect spectrum has been attributed to 'gastrointestinal hypomotility', gastrointestinal transit times in antipsychotic-treated patients have not previously been measured, making this mechanism speculative. Using standardized radiopaque marker ('Metcalf') methods we established colonic transit times of antipsychotic-treated psychiatric inpatients and compared them with population normative values. We analyzed results by antipsychotic type, antipsychotic dose equivalent, anticholinergic load, duration of treatment, gender, ethnicity, and age. For patients not prescribed clozapine, median colonic transit time was 23 h. For patients prescribed clozapine, median transit time was 104.5 h, over four times longer than those on other antipsychotics or normative values (p < 0.0001). Eighty percent of clozapine-treated patients had colonic hypomotility, compared with none of those prescribed other antipsychotics (olanzapine, risperidone, paliperidone aripiprazole, zuclopenthixol or haloperidol). In the clozapine group, right colon, left colon and rectosigmoid transit times were all markedly abnormal suggesting pan-colonic pathology. Hypomotility occurred irrespective of gender, age, ethnicity, or length of clozapine treatment. Transit times were positively correlated with clozapine plasma level (rho = 0.451, p = 0.045), but not with duration of treatment, total antipsychotic load or demographic factors. Clozapine, unlike the other antipsychotics examined, causes marked gastrointestinal hypomotility, as previously hypothesized. Pre-emptive laxative treatment is recommended when starting clozapine.

  12. [Applying uncertainty theory in caring for the family of a von Willebrand disease patient experiencing first time upper gastrointestinal bleeding].

    PubMed

    Chung, Ai-Lun; Shun, Shiow-Ching; Lin, Chih-Yu

    2009-10-01

    The purpose of this report was to describe the nursing experience in helping a primary caregiver cope with uncertainty as his mother experienced upper gastrointestinal (UGI) bleeding underlying von Willebrand disease and Scleromyxedema in an Emergency Department between 10 and 18 July 2008. Mishel's Uncertainty Theory was applied to assess the caregiver's uncertainty and patient disease progression. Data were collected through clinical observation, chart review, and interviews. The caregiver's nursing problems were identified as (1) uncertainty caused by symptoms of the rare disease and the probability of recurrent bleeding in the future; (2) uncertainty caused by lack of knowledge about the disease; (3) uncertainty caused by lack of confidence in home caring issues after UGI bleeding. During the nursing period, we provided clinical information related to the disease and offered psychological support to the caregiver based on our Mishel's Uncertainty Scale assessment. Successful strategies utilized by our intervention helped the caregiver reduce level of uncertainty, increase confidence to care for his mother, and improve the quality of further home care.

  13. Finite-time quantum-to-classical transition for a Schroedinger-cat state

    SciTech Connect

    Paavola, Janika; Hall, Michael J. W.; Paris, Matteo G. A.; Maniscalco, Sabrina

    2011-07-15

    The transition from quantum to classical, in the case of a quantum harmonic oscillator, is typically identified with the transition from a quantum superposition of macroscopically distinguishable states, such as the Schroedinger-cat state, into the corresponding statistical mixture. This transition is commonly characterized by the asymptotic loss of the interference term in the Wigner representation of the cat state. In this paper we show that the quantum-to-classical transition has different dynamical features depending on the measure for nonclassicality used. Measures based on an operatorial definition have well-defined physical meaning and allow a deeper understanding of the quantum-to-classical transition. Our analysis shows that, for most nonclassicality measures, the Schroedinger-cat state becomes classical after a finite time. Moreover, our results challenge the prevailing idea that more macroscopic states are more susceptible to decoherence in the sense that the transition from quantum to classical occurs faster. Since nonclassicality is a prerequisite for entanglement generation our results also bridge the gap between decoherence, which is lost only asymptotically, and entanglement, which may show a ''sudden death''. In fact, whereas the loss of coherences still remains asymptotic, we emphasize that the transition from quantum to classical can indeed occur at a finite time.

  14. Finite-time quantum-to-classical transition for a Schrödinger-cat state

    NASA Astrophysics Data System (ADS)

    Paavola, Janika; Hall, Michael J. W.; Paris, Matteo G. A.; Maniscalco, Sabrina

    2011-07-01

    The transition from quantum to classical, in the case of a quantum harmonic oscillator, is typically identified with the transition from a quantum superposition of macroscopically distinguishable states, such as the Schrödinger-cat state, into the corresponding statistical mixture. This transition is commonly characterized by the asymptotic loss of the interference term in the Wigner representation of the cat state. In this paper we show that the quantum-to-classical transition has different dynamical features depending on the measure for nonclassicality used. Measures based on an operatorial definition have well-defined physical meaning and allow a deeper understanding of the quantum-to-classical transition. Our analysis shows that, for most nonclassicality measures, the Schrödinger-cat state becomes classical after a finite time. Moreover, our results challenge the prevailing idea that more macroscopic states are more susceptible to decoherence in the sense that the transition from quantum to classical occurs faster. Since nonclassicality is a prerequisite for entanglement generation our results also bridge the gap between decoherence, which is lost only asymptotically, and entanglement, which may show a “sudden death.” In fact, whereas the loss of coherences still remains asymptotic, we emphasize that the transition from quantum to classical can indeed occur at a finite time.

  15. Gastrointestinal gas.

    PubMed Central

    Fardy, J; Sullivan, S

    1988-01-01

    Complaints related to gastrointestinal gas are commonly encountered in clinical practice. Various therapies have been proposed, yet none has appeared to be extremely effective. A review of the literature revealed little hard evidence to support the use of simethicone, pancreatic enzymes, anticholinergic agents or antibiotics. Evidence supporting the use of prokinetic agents has been the strongest, and there may be a pathophysiologic basis for the use of these agents if the complaints are related to abnormal intestinal motility. The use of activated charcoal for adsorbing intestinal gas has been effective in healthy subjects but has not been properly investigated in patients with gas complaints. Dietary modification may be beneficial in certain cases. Additional controlled trials are necessary to clarify the issues in the treatment of this common problem. PMID:3058280

  16. The detection and characterization of a nontransiting planet by transit timing variations.

    PubMed

    Nesvorný, David; Kipping, David M; Buchhave, Lars A; Bakos, Gáspár Á; Hartman, Joel; Schmitt, Allan R

    2012-06-01

    The Kepler mission is monitoring the brightness of ~150,000 stars, searching for evidence of planetary transits. As part of the Hunt for Exomoons with Kepler (HEK) project, we report a planetary system with two confirmed planets and one candidate planet discovered with the publicly available data for KOI-872. Planet b transits the host star with a period P(b) = 33.6 days and exhibits large transit timing variations indicative of a perturber. Dynamical modeling uniquely detects an outer nontransiting planet c near the 5:3 resonance (P(c) = 57.0 days) with a mass 0.37 times that of Jupiter. Transits of a third planetary candidate are also found: a 1.7-Earth radius super-Earth with a 6.8-day period. Our analysis indicates a system with nearly coplanar and circular orbits, reminiscent of the orderly arrangement within the solar system.

  17. Time-delayed transition of normal-to-abnormal glow in pin-to-water discharge

    SciTech Connect

    Yoon, S.-Y.; Byeon, Y.-S.; Yoo, S.; Hong, E. J.; Kim, S. B.; Yoo, S. J.; Ryu, S.

    2016-08-15

    Time-delayed transition of normal-to-abnormal glow was investigated in discharge between spoke-like pins and ultrapure water by applying AC-driven power at a frequency of 14.3 kHz at atmospheric pressure. The normal-to-abnormal transition can be recognized from the slope changes of current density, gas temperature, electrode temperature, and OH density. The slope changes took place in tens of minutes rather than just after discharge, in other words, the transition was delayed. The time-delay of the transition was caused by the interaction between the plasma and water. The plasma affected water properties, and then the water affected plasma properties.

  18. Time-delayed transition of normal-to-abnormal glow in pin-to-water discharge

    NASA Astrophysics Data System (ADS)

    Yoon, S.-Y.; Byeon, Y.-S.; Yoo, S.; Hong, E. J.; Kim, S. B.; Yoo, S. J.; Ryu, S.

    2016-08-01

    Time-delayed transition of normal-to-abnormal glow was investigated in discharge between spoke-like pins and ultrapure water by applying AC-driven power at a frequency of 14.3 kHz at atmospheric pressure. The normal-to-abnormal transition can be recognized from the slope changes of current density, gas temperature, electrode temperature, and OH density. The slope changes took place in tens of minutes rather than just after discharge, in other words, the transition was delayed. The time-delay of the transition was caused by the interaction between the plasma and water. The plasma affected water properties, and then the water affected plasma properties.

  19. Electric dipole transitions for four-times ionized cerium (Ce V)

    SciTech Connect

    Usta, Betül Karaçoban Akgün, Elif Alparslan, Büşra

    2016-03-25

    We have calculated the transition parameters, such as wavelengths, oscillator strengths, and transition probabilities (or rates), for the electric dipole (E1) transitions in four-times ionized cerium (Ce V, Z = 58) by using the multiconfiguration Hartree-Fock method within the framework of Breit-Pauli (MCHF+BP) relativistic corrections and the relativistic Hartree-Fock (HFR) method. The obtained results have been compared with other works available in literature. A discussion of these calculations for Ce V in this study has also been in view of the MCHF+BP and HFR methods.

  20. Abrupt shift of the pattern of diurnal variation in stroke onset with daylight saving time transitions.

    PubMed

    Foerch, Christian; Korf, Horst-Werner; Steinmetz, Helmuth; Sitzer, Matthias

    2008-07-15

    Stroke onset shows a pattern of diurnal variation, with a peak in morning hours. Rhythmic changes in blood pressure, hormones, and other parameters have been suggested as underlying mechanisms, but exogenous factors such as increasing physical activity after awakening may also be of relevance. To characterize the impact of external clock changes on the rhythmic variation in stroke onset, this parameter was recorded in patients during transition periods into and out of Daylight Saving Time (DST). The present study was based on a prospective stroke registry in Germany that contains time points of stroke onset from 44 251 patients admitted between 2000 and 2005. To achieve a uniform timeline, time points of stroke onset were set back from Central European Summer Time (CEST) to Central European Time (CET) for patients admitted during DST periods. Compared with the last week before the clock change, transition to or from DST resulted in an immediate shift of stroke onset time points within the first week after the clock change in reference to the uniform timeline (transition from CET to CEST -60 minutes for the time points in both the 25th and 50th percentiles of the diurnal pattern, P<0.001; transition from CEST to CET +60 minutes for the time points in both the 25th and 50th percentiles, P<0.001; patients pooled on a weekly basis). A significant shift was already present the first and second day after the transitions (ie, Monday and Tuesday). Transition to or from DST is coupled with an immediate shift in the time pattern of stroke onset. This strengthens the idea that exogenous factors associated with awakening are important determinants of the pattern of diurnal variation of stroke onset, because entrainment of the human circadian clock within hours is unlikely.

  1. Transit times and mean ages for nonautonomous and autonomous compartmental systems

    SciTech Connect

    Rasmussen, Martin; Hastings, Alan; Smith, Matthew J.; Agusto, Folashade B.; Chen-Charpentier, Benito M.; Hoffman, Forrest M.; Jiang, Jiang; Todd-Brown, Katherine E. O.; Wang, Ying; Wang, Ying -Ping; Luo, Yiqi

    2016-04-01

    In this study, we develop a theory for transit times and mean ages for nonautonomous compartmental systems. Using the McKendrick–von Förster equation, we show that the mean ages of mass in a compartmental system satisfy a linear nonautonomous ordinary differential equation that is exponentially stable. We then define a nonautonomous version of transit time as the mean age of mass leaving the compartmental system at a particular time and show that our nonautonomous theory generalises the autonomous case. We apply these results to study a nine-dimensional nonautonomous compartmental system modeling the terrestrial carbon cycle, which is a modification of the Carnegie–Ames–Stanford approach model, and we demonstrate that the nonautonomous versions of transit time and mean age differ significantly from the autonomous quantities when calculated for that model.

  2. Transit times and mean ages for nonautonomous and autonomous compartmental systems

    DOE PAGES

    Rasmussen, Martin; Hastings, Alan; Smith, Matthew J.; ...

    2016-04-01

    In this study, we develop a theory for transit times and mean ages for nonautonomous compartmental systems. Using the McKendrick–von Förster equation, we show that the mean ages of mass in a compartmental system satisfy a linear nonautonomous ordinary differential equation that is exponentially stable. We then define a nonautonomous version of transit time as the mean age of mass leaving the compartmental system at a particular time and show that our nonautonomous theory generalises the autonomous case. We apply these results to study a nine-dimensional nonautonomous compartmental system modeling the terrestrial carbon cycle, which is a modification of themore » Carnegie–Ames–Stanford approach model, and we demonstrate that the nonautonomous versions of transit time and mean age differ significantly from the autonomous quantities when calculated for that model.« less

  3. Prompting technologies: A comparison of time-based and context-aware transition-based prompting

    PubMed Central

    Robertson, Kayela; Rosasco, Cody; Feuz, Kyle; Schmitter-Edgecombe, Maureen; Cook, Diane

    2016-01-01

    BACKGROUND While advancements in technology have encouraged the development of novel prompting systems to support cognitive interventions, little research has evaluated the best time to deliver prompts, which may impact the effectiveness of these interventions. OBJECTIVE This study examined whether transition-based context prompting (prompting an individual during task transitions) is more effective than traditional fixed time-based prompting. METHODS Participants were 42 healthy adults who completed 12 different everyday activities, each lasting 1–7 minutes, in an experimental smart home testbed and received prompts to record the completed activities from an electronic memory notebook. Half of the participants were delivered prompts during activity transitions, while the other half received prompts every 5 minutes. Participants also completed Likert-scale ratings regarding their perceptions of the prompting system. RESULTS Results revealed that participants in the transition-based context prompting condition responded to the first prompt more frequently and rated the system as more convenient, natural, and appropriate compared to participants in the time-based condition. CONCLUSIONS Our findings suggest that prompting during activity transitions produces higher adherence to the first prompt and more positive perceptions of the prompting system. This is an important finding given the benefits of prompting technology and the possibility of improving cognitive interventions by using context-aware transition prompting. PMID:26409520

  4. Prompting technologies: A comparison of time-based and context-aware transition-based prompting.

    PubMed

    Robertson, Kayela; Rosasco, Cody; Feuz, Kyle; Schmitter-Edgecombe, Maureen; Cook, Diane

    2015-01-01

    While advancements in technology have encouraged the development of novel prompting systems to support cognitive interventions, little research has evaluated the best time to deliver prompts, which may impact the effectiveness of these interventions. This study examined whether transition-based context prompting (prompting an individual during task transitions) is more effective than traditional fixed time-based prompting. Participants were 42 healthy adults who completed 12 different everyday activities, each lasting 1-7 minutes, in an experimental smart home testbed and received prompts to record the completed activities from an electronic memory notebook. Half of the participants were delivered prompts during activity transitions, while the other half received prompts every 5 minutes. Participants also completed Likert-scale ratings regarding their perceptions of the prompting system. Results revealed that participants in the transition-based context prompting condition responded to the first prompt more frequently and rated the system as more convenient, natural, and appropriate compared to participants in the time-based condition. Our findings suggest that prompting during activity transitions produces higher adherence to the first prompt and more positive perceptions of the prompting system. This is an important finding given the benefits of prompting technology and the possibility of improving cognitive interventions by using context-aware transition prompting.

  5. New geometric transition as origin of particle production in time-dependent backgrounds

    NASA Astrophysics Data System (ADS)

    Kim, Sang Pyo

    2013-10-01

    By extending the quantum evolution of a scalar field in time-dependent backgrounds to the complex-time plane and transporting the in-vacuum along a closed path, we argue that the geometric transition from the simple pole at infinity determines the multi-pair production depending on the winding number. We apply the geometric transition to Schwinger mechanism in the time-dependent vector potential for a constant electric field and to Gibbons-Hawking particle production in the planar coordinates of a de Sitter space.

  6. Management of gastrointestinal hemorrhage.

    PubMed Central

    Hilsden, R. J.; Shaffer, E. A.

    1995-01-01

    Acute gastrointestinal hemorrhage is a common problem that requires prompt recognition and management to prevent serious morbidity and mortality. Management goals are stabilization of the patient with vigorous fluid resuscitation followed by investigation and definitive treatment of the bleeding source. Endoscopy is often the initial diagnostic test and allows therapeutic measures to be performed at the same time. Images Figure 1 Figure 2 PMID:8563510

  7. Gastrointestinal Dysfunction in Patients with Duchenne Muscular Dystrophy

    PubMed Central

    Latshang, Tsogyal D.; Bluemel, Sena; Frauenfelder, Thomas; Bloch, Konrad E.

    2016-01-01

    Background In adult patients with Duchenne muscular dystrophy (DMD) life-threatening constipation has been reported. Since gastrointestinal function in DMD has not been rigorously studied we investigated objective and subjective manifestations of gastrointestinal disturbances in DMD patients. Methods In 33 patients with DMD, age 12–41 years, eating behavior and gastrointestinal symptoms were evaluated by questionnaires. Gastric emptying half time (T1/2) and oro-cecal transit time (OCTT) were evaluated by analyzing 13CO2 exhalation curves after ingestion of 13C labeled test meals. Colonic transit time (CTT) was measured by abdominal radiography following ingestion of radiopaque markers. Results The median (quartiles) T1/2 was 187 (168, 220) minutes, the OCTT was 6.3 (5.0, 7.9) hours, both substantially longer than normal data (Goetze 2005, T1/2: 107±10; Geypens 1999, OCTT 4.3±0.1 hours). The median CTT was 60 (48, 82) hours despite extensive use of laxative measures (Meier 1995, upper limit of normal: 60 hours). T1/2 and OCTT did not correlate with symptoms evaluated by the Gastroparesis Cardinal Symptom Index (GCSI) (Spearman r = -0.3, p = 0.1; and r = -0.15, p = 0.4, respectively). CTT was not correlated with symptoms of constipation assessed by ROME III criteria (r = 0.12, p = 0.5). Conclusions DMD patients have a markedly disturbed gastrointestinal motor function. Since objective measures of impaired gastrointestinal transport are not correlated with symptoms of gastroparesis or constipation our findings suggest that measures assuring adequate intestinal transport should be taken independent of the patient’s perception in order to prevent potentially life threatening constipation, particularly in older DMD patients. PMID:27736891

  8. Bilateral transit time assessment of upper and lower limbs as a surrogate ankle brachial index marker.

    PubMed

    Foo, Jong Yong Abdiel

    2008-01-01

    Ankle brachial index is useful in monitoring the pathogenesis of peripheral arterial occlusive diseases. Sphygmomanometer is the standard instrument widely used but frequent prolonged monitoring can be less comfortable for patients. Pulse transit time is known to be inversely correlated with blood pressure and a ratio-based pulse transit time measurement has been proposed as a surrogate ankle brachial index marker. In this study, 17 normotensive adults (9 men; aged 25.4 +/- 3.9 years) were recruited. Two postural change test activities were performed to induce changes in the stiffness of the arterial wall of the moved periphery. Results showed that only readings from the limbs that adopted a new posture registered significant blood pressure and pulse transit time changes (P < .05). Furthermore, there was significant correlation between the ankle brachial index and pulse transit time ratio measure for both test activities (R(2) > or = 0.704). The findings herein suggest that pulse transit time ratio is a surrogate and accommodating ankle brachial index marker.

  9. The Influence of Unpaid Work on the Transition Out of Full-Time Paid Work

    PubMed Central

    Carr, Dawn C.

    2013-01-01

    Purpose: Continued employment after retirement and engagement in unpaid work are both important ways of diminishing the negative economic effects of the retirement of baby boomer cohorts on society. Little research, however, examines the relationship between paid and unpaid work at the transition from full-time work. Using a resource perspective framework this study examines how engagement in unpaid work prior to and at the transition from full-time work influences whether individuals partially or fully retire. Design and Methods: This study used a sample of 2,236 Americans between the ages 50 and 68, who were interviewed between 1998 and 2008. Logistic regression was used to estimate transitioning into partial retirement (relative to full retirement) after leaving full-time work. Results: We found that the odds of transitioning into part-time work were increased by continuous volunteering (78%) and reduced by starting parental (84%), grandchild (41%), and spousal (90%) caregiving and unaffected by all other patterns of engagement in unpaid work. Implications: Our findings suggest that volunteering is complementary with a transition to part-time work, and starting a new caregiving role at this transitioncreates a barrier to continued employment. In order to provide workers the opportunity to engage in the work force longer at the brink of retirement, it may be necessary to increase the support mechanisms for those who experience new caregiving responsibilities. PMID:22859436

  10. Evaluation of transit-time and electromagnetic flow measurement in a chronically instrumented nonhuman primate model.

    PubMed

    Koenig, S C; Reister, C A; Schaub, J; Swope, R D; Ewert, D; Fanton, J W

    1996-01-01

    The Physiology Research Branch at Brooks AFB conducts both human and nonhuman primate experiments to determine the effects of microgravity and hypergravity on the cardiovascular system and to identify the particular mechanisms that invoke these responses. Primary investigative efforts in our nonhuman primate model require the determination of total peripheral resistance, systemic arterial compliance, and pressure-volume loop characteristics. These calculations require beat-to-beat measurement of aortic flow. This study evaluated accuracy, linearity, biocompatability, and anatomical features of commercially available electromagnetic (EMF) and transit-time flow measurement techniques. Five rhesus monkeys were instrumented with either EMF (3 subjects) or transit-time (2 subjects) flow sensors encircling the proximal ascending aorta. Cardiac outputs computed from these transducers taken over ranges of 0.5 to 2.0 L/min were compared to values obtained using thermodilution. In vivo experiments demonstrated that the EMF probe produced an average error of 15% (r = .896) and 8.6% average linearity per reading, and the transit-time flow probe produced an average error of 6% (r = .955) and 5.3% average linearity per reading. Postoperative performance and biocompatability of the probes were maintained throughout the study. The transit-time sensors provided the advantages of greater accuracy, smaller size, and lighter weight than the EMF probes. In conclusion, the characteristic features and performance of the transit-time sensors were superior to those of the EMF sensors in this study.

  11. Evaluation of transit-time and electromagnetic flow measurement in a chronically instrumented nonhuman primate model

    NASA Technical Reports Server (NTRS)

    Koenig, S. C.; Reister, C. A.; Schaub, J.; Swope, R. D.; Ewert, D.; Fanton, J. W.; Convertino, V. A. (Principal Investigator)

    1996-01-01

    The Physiology Research Branch at Brooks AFB conducts both human and nonhuman primate experiments to determine the effects of microgravity and hypergravity on the cardiovascular system and to identify the particular mechanisms that invoke these responses. Primary investigative efforts in our nonhuman primate model require the determination of total peripheral resistance, systemic arterial compliance, and pressure-volume loop characteristics. These calculations require beat-to-beat measurement of aortic flow. This study evaluated accuracy, linearity, biocompatability, and anatomical features of commercially available electromagnetic (EMF) and transit-time flow measurement techniques. Five rhesus monkeys were instrumented with either EMF (3 subjects) or transit-time (2 subjects) flow sensors encircling the proximal ascending aorta. Cardiac outputs computed from these transducers taken over ranges of 0.5 to 2.0 L/min were compared to values obtained using thermodilution. In vivo experiments demonstrated that the EMF probe produced an average error of 15% (r = .896) and 8.6% average linearity per reading, and the transit-time flow probe produced an average error of 6% (r = .955) and 5.3% average linearity per reading. Postoperative performance and biocompatability of the probes were maintained throughout the study. The transit-time sensors provided the advantages of greater accuracy, smaller size, and lighter weight than the EMF probes. In conclusion, the characteristic features and performance of the transit-time sensors were superior to those of the EMF sensors in this study.

  12. Evaluation of transit-time and electromagnetic flow measurement in a chronically instrumented nonhuman primate model

    NASA Technical Reports Server (NTRS)

    Koenig, S. C.; Reister, C. A.; Schaub, J.; Swope, R. D.; Ewert, D.; Fanton, J. W.; Convertino, V. A. (Principal Investigator)

    1996-01-01

    The Physiology Research Branch at Brooks AFB conducts both human and nonhuman primate experiments to determine the effects of microgravity and hypergravity on the cardiovascular system and to identify the particular mechanisms that invoke these responses. Primary investigative efforts in our nonhuman primate model require the determination of total peripheral resistance, systemic arterial compliance, and pressure-volume loop characteristics. These calculations require beat-to-beat measurement of aortic flow. This study evaluated accuracy, linearity, biocompatability, and anatomical features of commercially available electromagnetic (EMF) and transit-time flow measurement techniques. Five rhesus monkeys were instrumented with either EMF (3 subjects) or transit-time (2 subjects) flow sensors encircling the proximal ascending aorta. Cardiac outputs computed from these transducers taken over ranges of 0.5 to 2.0 L/min were compared to values obtained using thermodilution. In vivo experiments demonstrated that the EMF probe produced an average error of 15% (r = .896) and 8.6% average linearity per reading, and the transit-time flow probe produced an average error of 6% (r = .955) and 5.3% average linearity per reading. Postoperative performance and biocompatability of the probes were maintained throughout the study. The transit-time sensors provided the advantages of greater accuracy, smaller size, and lighter weight than the EMF probes. In conclusion, the characteristic features and performance of the transit-time sensors were superior to those of the EMF sensors in this study.

  13. The Ebb and Flow of Filipino First-Time Fatherhood Transition Space: A Grounded Theory Study.

    PubMed

    Villamor, Neil Jupiter E; de Guzman, Allan B; Matienzo, Evangeline T

    2016-11-01

    Fatherhood, as a developmental process, is both a human experience and a text that needs to be read. For developing nations like the Philippines, little is known about the process undergone by first-time fathers on their transition to fatherhood, and how nurses can play a significant role in assisting them. This grounded theory study purported to conceptualize the multifaceted process of transition from the lens of Filipino first-time fathers' lived experiences. A total of 20 first-time fathers from Metro Manila, Philippines, were purposively selected to take part in an individual, semistructured, and in-depth interview. The Glaserian (classical) method of analysis was specifically used, and field texts were inductively analyzed using a repertory grid. Member checking and correspondence were done to validate the findings of the study. Six surfacing stages emerged relative to the process of transition. Interestingly, The B.R.I.D.G.E. Theory of First-Time Fatherhood Transition Space describes how these fathers progress from the beholding, reorganizing, inhibiting, delivering, grasping, and embracing phases toward successful transition. This emerged theoretical model can be used in framing health care programs where the needs of fathers during this period are met and addressed. Finally, it can also be used in guiding nurses in their provision of a more empathetic care for first-time fathers.

  14. The influence of unpaid work on the transition out of full-time paid work.

    PubMed

    Carr, Dawn C; Kail, Ben Lennox

    2013-02-01

    Continued employment after retirement and engagement in unpaid work are both important ways of diminishing the negative economic effects of the retirement of baby boomer cohorts on society. Little research, however, examines the relationship between paid and unpaid work at the transition from full-time work. Using a resource perspective framework this study examines how engagement in unpaid work prior to and at the transition from full-time work influences whether individuals partially or fully retire. This study used a sample of 2,236 Americans between the ages 50 and 68, who were interviewed between 1998 and 2008. Logistic regression was used to estimate transitioning into partial retirement (relative to full retirement) after leaving full-time work. We found that the odds of transitioning into part-time work were increased by continuous volunteering (78%) and reduced by starting parental (84%), grandchild (41%), and spousal (90%) caregiving and unaffected by all other patterns of engagement in unpaid work. Our findings suggest that volunteering is complementary with a transition to part-time work, and starting a new caregiving role at this transitioncreates a barrier to continued employment. In order to provide workers the opportunity to engage in the work force longer at the brink of retirement, it may be necessary to increase the support mechanisms for those who experience new caregiving responsibilities.

  15. Timing of Parenthood in Relation to Other Life Transitions and Adult Social Functioning

    ERIC Educational Resources Information Center

    Kokko, Katja; Pulkkinen, Lea; Mesiainen, Paivi

    2009-01-01

    The timing of having one's first child, in relation to the timing of other transitions into adulthood and to social functioning, was investigated based on the Finnish Jyvaskyla Longitudinal Study of Personality and Social Development, conducted from age 8 (173 females and 196 males) to 42. Results showed that in women, relatively early (less than…

  16. The role of time scale separation in a nonequilibrium roughening transition

    NASA Astrophysics Data System (ADS)

    Llas, M.; Díaz-Guilera, A.; López, J. M.; Gleiser, P. M.

    2007-01-01

    In this work we analyze the role of time scale separation between the external driving and the avalanche relaxation dynamics in a one-dimensional model of propagation of innovations among economic agents. When the time scales are separated the model presents a nonequilibrium roughening transition. We show that when avalanche overlapping is permitted, only a rough phase is observed.

  17. Determining the architecture of the Kepler-297 system using transit timing variations

    NASA Astrophysics Data System (ADS)

    Diamond-Lowe, Hannah; Stevenson, Kevin B.; Fabrycky, Daniel; Ballard, Sarah; Agol, Eric; Bean, Jacob; Holman, Matthew J.; Ragozzine, Darin

    2015-01-01

    It is essential to explore the architectures of exoplanetary systems as we attempt to understand planet formation histories and determine the rate of occurrence of habitable-zone rocky planets. We focus on the Kepler-297 system which hosts three transiting planets, Kepler-297b, Kepler-297c, and KOI-1426.03. We re-analyze extant Kepler data of the system, as well as new Spitzer data of Kepler-297c, to constrain the transit time variations (TTVs) of the three transiting planets in the system. We feed these results into a dynamical analysis in which the TTVs of the transiting planets constrain their orbital parameters, as well as those of potential non-transiting planets. The gravitational interactions between the Kepler-297 planets allow us to derive their mass ratios. We find that the orbital parameters of the three transiting planets are well-fit by a model that includes a non-transiting fourth planet outside of the three transitors. We are also able to constrain the orbital parameters of the outer-most transitor, thereby confirming it as the planet Kepler-297d.

  18. Pulse-echo ultrasound transit time spectroscopy: A comparison of experimental measurement and simulation prediction.

    PubMed

    Wille, Marie-Luise; Almualimi, Majdi A; Langton, Christian M

    2016-01-01

    Considering ultrasound propagation through complex composite media as an array of parallel sonic rays, a comparison of computer-simulated prediction with experimental data has previously been reported for transmission mode (where one transducer serves as transmitter, the other as receiver) in a series of 10 acrylic step-wedge samples, immersed in water, exhibiting varying degrees of transit time inhomogeneity. In this study, the same samples were used but in pulse-echo mode, where the same ultrasound transducer served as both transmitter and receiver, detecting both 'primary' (internal sample interface) and 'secondary' (external sample interface) echoes. A transit time spectrum was derived, describing the proportion of sonic rays with a particular transit time. A computer simulation was performed to predict the transit time and amplitude of various echoes created, and compared with experimental data. Applying an amplitude-tolerance analysis, 91.7% ± 3.7% of the simulated data were within ±1 standard deviation of the experimentally measured amplitude-time data. Correlation of predicted and experimental transit time spectra provided coefficients of determination (R(2)%) ranging from 100.0% to 96.8% for the various samples tested. The results acquired from this study provide good evidence for the concept of parallel sonic rays. Furthermore, deconvolution of experimental input and output signals has been shown to provide an effective method to identify echoes otherwise lost due to phase cancellation. Potential applications of pulse-echo ultrasound transit time spectroscopy include improvement of ultrasound image fidelity by improving spatial resolution and reducing phase interference artefacts.

  19. Transition state geometry of driven chemical reactions on time-dependent double-well potentials.

    PubMed

    Junginger, Andrej; Craven, Galen T; Bartsch, Thomas; Revuelta, F; Borondo, F; Benito, R M; Hernandez, Rigoberto

    2016-11-09

    Reaction rates across time-dependent barriers are difficult to define and difficult to obtain using standard transition state theory approaches because of the complexity of the geometry of the dividing surface separating reactants and products. Using perturbation theory (PT) or Lagrangian descriptors (LDs), we can obtain the transition state trajectory and the associated recrossing-free dividing surface. With the latter, we are able to determine the exact reactant population decay and the corresponding rates to benchmark the PT and LD approaches. Specifically, accurate rates are obtained from a local description regarding only direct barrier crossings and to those obtained from a stability analysis of the transition state trajectory. We find that these benchmarks agree with the PT and LD approaches for obtaining recrossing-free dividing surfaces. This result holds not only for the local dynamics in the vicinity of the barrier top, but also for the global dynamics of particles that are quenched at the reactant or product wells after their sojourn over the barrier region. The double-well structure of the potential allows for long-time dynamics related to collisions with the outside walls that lead to long-time returns in the low-friction regime. This additional global dynamics introduces slow-decay pathways that do not result from the local transition across the recrossing-free dividing surface associated with the transition state trajectory, but can be addressed if that structure is augmented by the population transfer of the long-time returns.

  20. Time scheduling of transit systems with transfer considerations using genetic algorithms.

    PubMed

    Deb, K; Chakroborty, P

    1998-01-01

    Scheduling of a bus transit system must be formulated as an optimization problem, if the level of service to passengers is to be maximized within the available resources. In this paper, we present a formulation of a transit system scheduling problem with the objective of minimizing the overall waiting time of transferring and nontransferring passengers while satisfying a number of resource- and service-related constraints. It is observed that the number of variables and constraints for even a simple transit system (a single bus station with three routes) is too large to tackle using classical mixed-integer optimization techniques. The paper shows that genetic algorithms (GAs) are ideal for these problems, mainly because they (i) naturally handle binary variables, thereby taking care of transfer decision variables, which constitute the majority of the decision variables in the transit scheduling problem; and (ii) allow procedure-based declarations, thereby allowing complex algorithmic approaches (involving if then-else conditions) to be handled easily. The paper also shows how easily the same GA procedure with minimal modifications can handle a number of other more pragmatic extensions to the simple transit scheduling problem: buses with limited capacity, buses that do not arrive exactly as per scheduled times, and a multiple-station transit system having common routes among bus stations. Simulation results show the success of GAs in all these problems and suggest the application of GAs in more complex scheduling problems.

  1. Transit time of a freely falling quantum particle in a background gravitational field

    NASA Astrophysics Data System (ADS)

    Davies, P. C. W.

    2004-12-01

    Using a model quantum clock, I evaluate an expression for the time of a non-relativistic quantum particle to transit a piecewise geodesic path in a background gravitational field with small spacetime curvature (gravity gradient), in the case in which the apparatus is in free fall. This calculation complements and extends an earlier one (Davies 2004) in which the apparatus is fixed to the surface of the Earth. The result confirms that, for particle velocities not too low, the quantum and classical transit times coincide, in conformity with the principle of equivalence. I also calculate the quantum corrections to the transit time when the de Broglie wavelengths are long enough to probe the spacetime curvature. The results are compared with the calculation of Chiao and Speliotopoulos (2003), who propose an experiment to measure the foregoing effects.

  2. Decreasing transition times in elementary school classrooms: Using computer-assisted instruction to automate intervention components.

    PubMed

    Hine, Jeffrey F; Ardoin, Scott P; Foster, Tori E

    2015-09-01

    Research suggests that students spend a substantial amount of time transitioning between classroom activities, which may reduce time spent academically engaged. This study used an ABAB design to evaluate the effects of a computer-assisted intervention that automated intervention components previously shown to decrease transition times. We examined the effects of the intervention on the latency to on-task behavior of 4 students in 2 classrooms. Data also were collected on students' on-task behavior during activities and teachers' use of prompts and praise statements. Implementation of the intervention substantially decreased students' latencies to on-task behavior and increased on-task behavior overall. Further, the 2 teachers used fewer prompts to cue students to transition and stay on task and provided more praise during intervention phases. We discuss how automating classroom interventions may affect student and teacher behavior as well as how it may increase procedural fidelity.

  3. Finite-time thermodynamics and the gas-liquid phase transition

    NASA Astrophysics Data System (ADS)

    Santoro, M.; Schön, J. C.; Jansen, M.

    2007-12-01

    In this paper, we study the application of the concept of finite-time thermodynamics to first-order phase transitions. As an example, we investigate the transition from the gaseous to the liquid state by modeling the liquification of the gas in a finite time. In particular, we introduce, state, and solve an optimal control problem in which we aim at achieving the gas-liquid first-order phase transition through supersaturation within a fixed time in an optimal fashion, in the sense that the work required to supersaturate the gas, called excess work, is minimized by controlling the appropriate thermodynamic parameters. The resulting set of coupled nonlinear differential equations is then solved for three systems, nitrogen N2 , oxygen O2 , and water vapor H2O .

  4. The Transit-Time Distribution from the Northern Hemisphere Midlatitude Surface

    NASA Technical Reports Server (NTRS)

    Orbe, Clara; Waugh, Darryn W.; Newman, Paul A.; Strahan, Susan; Steenrod, Stephen

    2015-01-01

    The distribution of transit times from the Northern Hemisphere (NH) midlatitude surface is a fundamental property of tropospheric transport. Here we present an analysis of the transit time distribution (TTD) since air last contacted the northern midlatitude surface layer, as simulated by the NASA Global Modeling Initiative Chemistry Transport Model. We find that throughout the troposphere the TTD is characterized by long flat tails that reflect the recirculation of old air from the Southern Hemisphere and results in mean ages that are significantly larger than the modal age. Key aspects of the TTD -- its mode, mean and spectral width -- are interpreted in terms of tropospheric dynamics, including seasonal shifts in the location and strength of tropical convection and variations in quasi-isentropic transport out of the northern midlatitude surface layer. Our results indicate that current diagnostics of tropospheric transport are insufficient for comparing model transport and that the full distribution of transit times is a more appropriate constraint.

  5. Finite-time H∞ control for stochastic time-delayed Markovian switching systems with partly known transition rates and nonlinearity

    NASA Astrophysics Data System (ADS)

    Qi, Wenhai; Gao, Xianwen

    2016-01-01

    This paper focuses on the problem of finite-time H∞ control for stochastic time-delayed Markovian switching systems with partly known transition rates and nonlinearity. By employing an appropriate Lyapunov function and some appropriate free-weighting matrices, a state feedback controller is designed to ensure H∞ finite-time boundedness of the resulting closed-loop system that contains time-varying delay, admissible external disturbance, It ?-type stochastic disturbance and nonlinearity. All the proposed conditions are established in the form of linear matrix inequalities. Finally, an example is given to demonstrate the validity of the main results.

  6. Nonlinear light behaviors near phase transition in non-parity-time-symmetric complex waveguides.

    PubMed

    Nixon, Sean; Yang, Jianke

    2016-06-15

    Many classes of non-parity-time (PT)-symmetric waveguides with arbitrary gain and loss distributions still possess all-real linear spectrum or exhibit phase transition. In this Letter, nonlinear light behaviors in these complex waveguides are probed analytically near a phase transition. Using multi-scale perturbation methods, a nonlinear ordinary differential equation (ODE) is derived for the light's amplitude evolution. This ODE predicts that a single class of these non-PT-symmetric waveguides supports soliton families and amplitude-oscillating solutions both above and below linear phase transition, in close analogy with PT-symmetric systems. For the other classes of waveguides, the light's intensity always amplifies under the effect of nonlinearity, even if the waveguide is below the linear phase transition. These analytical predictions are confirmed by direct computations of the full system.

  7. Reconciling transition path time and rate measurements in reactions with large entropic barriers

    NASA Astrophysics Data System (ADS)

    Makarov, Dmitrii E.

    2017-02-01

    Recent experiments and simulation studies showed that protein/DNA folding barriers inferred from folding rates or from potentials of mean force are often much higher than the barriers estimated from the distributions of transition path times. Here a toy model is used to explain a possible origin of this effect: It is shown that when the transition in question involves an entropic barrier, the one-dimensional Langevin model commonly used to interpret experimental data, while adequately predicting the transition rate, fails to describe the properties of the subset of the trajectories that form the transition path ensemble; the latter may still be describable in terms of a one-dimensional model, but with a different potential, just as observed experimentally.

  8. Transit timing variation analysis in southern stars: the case of WASP-28

    NASA Astrophysics Data System (ADS)

    Petrucci, R.; Jofré, E.; Melita, M.; Gómez, M.; Mauas, P.

    2015-01-01

    We present four new transit observations of the exoplanet WASP-28b observed between 2011 August and 2013 October. Employing another 11 transits available in the literature we compute new ephemeris and redetermine the physical parameters of the star and the exoplanet. Considering 3 yr of observations, we find no periodic transit timing variations (TTVs) or long-term variations of the inclination of the orbit, i, or the depth of the transit, k, that could be attributable to the presence of another planetary-mass body in the system. We also study the relations between i and k with different factors that characterize the light curves. The fits suggest a possible weak correlation between k with the red noise factor, β, and the photometric noise rate, PNR, and a weak anticorrelation between i and PNR, although more points are needed to confirm these trends. Finally, the kinematic study suggests that WASP-28 is a thin-disc star.

  9. Reconciling transition path time and rate measurements in reactions with large entropic barriers.

    PubMed

    Makarov, Dmitrii E

    2017-02-21

    Recent experiments and simulation studies showed that protein/DNA folding barriers inferred from folding rates or from potentials of mean force are often much higher than the barriers estimated from the distributions of transition path times. Here a toy model is used to explain a possible origin of this effect: It is shown that when the transition in question involves an entropic barrier, the one-dimensional Langevin model commonly used to interpret experimental data, while adequately predicting the transition rate, fails to describe the properties of the subset of the trajectories that form the transition path ensemble; the latter may still be describable in terms of a one-dimensional model, but with a different potential, just as observed experimentally.

  10. Determination of erythrocyte transit times through micropores. II. Influence of experimental and physicochemical factors.

    PubMed

    Koutsouris, D; Guillet, R; Wenby, R B; Meiselman, H J

    1989-01-01

    A new red blood cell filtration system, termed the Cell Transit Time Analyzer (CTTA), has been developed in order to measure the individual transit times of a large number of cells through cylindrical micropores in special "oligopore" filters; the system operates on the electrical conductometric principle and employs special computer software to provide several measures of the resulting transit time histogram. Using this system with filters having pore diameters of 4.5 or 5.0 microns and length to diameter ratios of 3.0 to 4.7, we have evaluated the effects of several experimental factors on the flow behavior of normal and modified human RBC. Our results indicate: 1) linear RBC pressure-flow behavior over a driving pressure range of 2 to 10.5 cm H2O with zero velocity intercepts at delta P = 0, thus suggesting the Poiseuille-like nature of the flow; 2) resistance to flow or "apparent viscosities" for normal RBC which are between 3.1 to 3.9 cPoise and are independent of driving pressure and pore geometry; 3) increased flow resistance (i.e., increased transit times) for old versus young RBC and for RBC made less deformable by DNP-induced crenation or by heat treatment at 48 degrees C; 4) increased mean transit time and poorer reproducibility when using EDTA rather than heparin as the anticoagulant agent. Further, using mixtures of heat-treated and normal RBC and various percentile values of the transit time histogram, we have been able to demonstrate the presence of sub-populations of rigid cells and thus the value of measurements which allow statistical analyses of RBC populations.

  11. Physical activity during video capsule endoscopy correlates with shorter bowel transit time.

    PubMed

    Stanich, Peter P; Peck, Joshua; Murphy, Christopher; Porter, Kyle M; Meyer, Marty M

    2017-09-01

     Video capsule endoscopy (VCE) is limited by reliance on bowel motility for propulsion, and lack of physical activity has been proposed as a cause of incomplete studies. Our aim was to prospectively investigate the association between physical activity and VCE bowel transit.  Ambulatory outpatients receiving VCE were eligible for the study. A pedometer was attached at the time of VCE ingestion and step count was recorded at the end of the procedure. VCE completion was assessed by logistic regression models, which included step count (500 steps as one unit). Total transit time was analyzed by Cox proportional hazards models. The hazard ratios (HR) with 95 % confidence interval (CI) indicated the "hazard" of completion, such that HRs > 1 indicated a reduced transit time.  A total of 100 patients were included. VCE was completed in 93 patients (93 %). The median step count was 2782 steps. Step count was not significantly associated with VCE completion (odds ratio 1.45, 95 %CI 0.84, 2.49). Pedometer step count was significantly associated with shorter total, gastric, and small-bowel transit times (HR 1.09, 95 %CI 1.03, 1.16; HR 1.05, 95 %CI 1.00, 1.11; HR 1.07, 95 %CI 1.01, 1.14, respectively). Higher body mass index (BMI) was significantly associated with VCE completion (HR 1.87, 95 %CI 1.18, 2.97) and shorter bowel transit times (HR 1.05, 95 %CI 1.02, 1.08).  Increased physical activity during outpatient VCE was associated with shorter bowel transit times but not with study completion. In addition, BMI was a previously unreported clinical characteristic associated with VCE completion and should be included as a variable of interest in future studies.

  12. Mean transit times in contrasting headwater catchments from southeast Australia determined using Tritium

    NASA Astrophysics Data System (ADS)

    Cartwright, Ian; Morgenstern, Uwe; Irvine, Dylan

    2016-04-01

    Headwater streams contribute a significant proportion of the total discharge of many river systems. However, despite their importance, the time taken for rainfall to pass through the catchment into the streams (the transit time) in headwater catchments is largely unknown as are the catchment characteristics (such as drainage density, topography, landuse, or geology) that determine variations in transit times. Because the peak in Tritium activities in rainfall produced by atmospheric nuclear tests in the1950's and 1960's (the "bomb-pulse") was several orders of magnitude lower in the southern hemisphere than in the northern hemisphere, Tritium activities of remnant bomb pulse water in the southern hemisphere have decayed below those of modern rainfall. This allows mean transit times to be estimated from single Tritium measurements. Here we use Tritium to estimate transit times of water contributing to perennial streams in the adjacent upper catchments of the Yarra and Latrobe Rivers (southeast Australia). Samples were collected at varying flow from six headwater tributary sites in the Latrobe catchment, which is largely forested and four tributaries in the Yarra catchment which has been extensively cleared for dryland agriculture. The lowest Tritium activities were recorded during summer baseflow conditions and are between 1.25 and 1.75 TU, these are significantly below the Tritium activity of local rainfall (~2.8 TU). Mean transit times calculated using an exponential-piston flow lumped parameter model are 21 to 47 years. Tritium activities during the recession periods following winter high flows are higher (1.54 to 2.1 TU), which may reflect either the dilution of a baseflow component with recent surface runoff or mobilisation of different stores of water with different residence times (e.g., from the soils or the regolith) from within the catchment. The variation of major ion concentrations with discharge suggests it is more likely that that different stores of

  13. Application of transit timing variation method (TTV) to exoplanet system TrES-3

    NASA Astrophysics Data System (ADS)

    Kuznyetsova, Yu.; Shliakhetskaya, Y.; Matsiaka, O.; Krushevska, V.; Romanyuk, Ya.

    2015-10-01

    On the basis of the original photometric data, the light curves of several transits in the exoplanet system TrES-3 were simulated by Monte Carlo method. Using these curves, the estimates of precise values of mid-transit time were calculated to assess the possibility of finding new planets by timing method in already known exoplanet systems using ground-based observations at small telescopes. More accurate values of the some orbital and physical parameters of TrES-3 system were also obtained including following the planet-star radius ratio (RP/R*), the angle of the planet orbital plane inclination (i).

  14. Nonlinear ion dynamics in Hall thruster plasma source by ion transit-time instability

    NASA Astrophysics Data System (ADS)

    Lim, Youbong; Choe, Wonho; Mazouffre, Stéphane; Park, Jae Sun; Kim, Holak; Seon, Jongho; Garrigues, L.

    2017-03-01

    High-energy tail formation in an ion energy distribution function (IEDF) is explained in a Hall thruster plasma with the stationary crossed electric and magnetic fields whose discharge current is oscillated at the ion transit-time scale with a frequency of 360 kHz. Among ions in different charge states, singly charged Xe ions (Xe+) have an IEDF that is significantly broadened and shifted toward the high-energy side, which contributes to tail formation in the entire IEDF. Analytical and numerical investigations confirm that the IEDF tail is due to nonlinear ion dynamics in the ion transit-time oscillation.

  15. Study of the transit time of pressure propagation in an acoustic delay line

    NASA Astrophysics Data System (ADS)

    Song, Yunn-Fang; Chen, Ching-Iue; Chang, Chu-Nan; You, Jean-Luh; Hwang, Fu-Kwun; Hsu, Chih-Ying

    1986-12-01

    A fast sensor was used as a vacuum gauge to measure the transit time of a gas pressure through an acoustic delay line (ADL). The results were compared with the predictions of two theoretical models. We found that in the rupture pressure range of 101 to 104 Pa, the predictions of Jean and Rauss' model, based on the assumption that the flow of gas be a gas fluid, set lower boundaries for the observed transit times; while the predictions of our model, based on the molecular motion, set the upper ones.

  16. Pulse transit time as a surrogate measure of changes in systolic arterial pressure in children during sleep.

    PubMed

    Vlahandonis, Anna; Biggs, Sarah N; Nixon, Gillian M; Davey, Margot J; Walter, Lisa M; Horne, Rosemary S C

    2014-08-01

    Pulse transit time has been proposed as a surrogate measure of systolic arterial pressure, as it is dependent upon arterial stiffness. Past research has shown that pulse transit time has a significant inverse relationship to systolic arterial pressure in adults; however, studies in children are limited. This study aimed to explore the relationship between systolic arterial pressure and pulse transit time in children during sleep. Twenty-five children (13.1 ± 1.6 years, 48% male) underwent overnight polysomnography (PSG) with a simultaneous recording of continuous systolic arterial pressure and photoplethysmography. Pulse transit time was calculated as the time delay between the R-wave peak of the electrocardiogram (ECG) to the 50% point of the upstroke of the corresponding photoplethysmography waveform; 500 beats of simultaneous systolic arterial pressure and pulse transit time were analysed in each sleep stage for each child. Pulse transit time was normalized to each subject's mean wake pulse transit time. The ability of pulse transit time to predict systolic arterial pressure change was determined by linear mixed-effects modelling. Significant negative correlations between pulse transit time and systolic arterial pressure were found for individual children for each sleep stage [mean correlations for cohort: non-rapid eye movement (NREM) sleep 1 and 2 r = -0.57, slow wave sleep (SWS) r = -0.76, REM r = -0.65, P < 0.01 for all]. Linear mixed-model analysis demonstrated that changes in pulse transit time were a significant predictor of changes in systolic arterial pressure for each sleep stage (P < 0.001). The model of pulse transit time-predicted systolic arterial pressure closely tracked actual systolic arterial pressure changes over time. This study demonstrated that pulse transit time was accurate in tracking systolic arterial pressure changes over time. Thus, the use of pulse transit time as a surrogate measure of changes in systolic arterial pressure in

  17. Hydroclimatic influences on non-stationary transit time distributions in a boreal headwater catchment

    NASA Astrophysics Data System (ADS)

    Peralta-Tapia, A.; Soulsby, C.; Tetzlaff, D.; Sponseller, R.; Bishop, K.; Laudon, H.

    2016-12-01

    Understanding how water moves through catchments - from the time it enters as precipitation to when it exits via streamflow - is of fundamental importance to understanding hydrological and biogeochemical processes. A basic descriptor of this routing is the Transit Time Distribution (TTD) which is derived from the input-output behavior of conservative tracers, the mean of which represents the average time elapsed between water molecules entering and exiting a flow system. In recent decades, many transit time studies have been conducted, but few of these have focused on snow-dominated catchments. We assembled a 10-year time series of isotopic data (δ18O and δ2H) for precipitation and stream water to estimate the characteristics of the transit time distribution in a boreal catchment in northern Sweden. We applied lumped parameter models using a gamma distribution to calculate the Mean Transit Time (MTT) of water over the entire period of record and to evaluate how inter-annual differences in transit times relate to hydroclimatic variability. The best fit MTT for the complete 10-year period was 650 days (Nash-Sutcliff Efficiency = 0.65), while the best fit inter-annual MTT ranged from 300 days up to 1200 days. Whilst there was a weak negative correlation between mean annual total precipitation and the annual MTT, this relationship was stronger (r2 = 0.53, p = 0.02) for the annual rain water input. This strong connection between the MTT and annual rainfall, rather than snowmelt, has strong implications for understanding future hydrological and biogeochemical processes in boreal regions, given that predicted warmer winters would translate into a greater proportion of precipitation falling as rain and thus shorter MTT in catchments. Such a change could have direct implications for the export of solutes and pollutants.

  18. QUANTIFYING THE CHALLENGES OF DETECTING UNSEEN PLANETARY COMPANIONS WITH TRANSIT TIMING VARIATIONS

    SciTech Connect

    Veras, Dimitri; Ford, Eric B.; Payne, Matthew J.

    2011-02-01

    Both ground- and space-based transit observatories are poised to significantly increase the number of known transiting planets and the number of precisely measured transit times. The variation in a planet's transit times may be used to infer the presence of additional planets. Deducing the masses and orbital parameters of such planets from transit time variations (TTVs) alone is a rich and increasingly relevant dynamical problem. In this work, we evaluate the extent of the degeneracies in this process, systematically explore the dependence of TTV signals on several parameters, and provide phase space plots that could aid observers in planning future observations. Our explorations are focused on a likely-to-be prevalent situation: a known transiting short-period Neptune- or Jupiter-sized planet and a suspected external low-mass perturber on a nearly coplanar orbit. Through {approx}10{sup 7} N-body simulations, we demonstrate how TTV signal amplitudes may vary by orders of magnitude due to slight variations in any one orbital parameter (10{sup -3} AU in a semimajor axis, 0.005 in eccentricity, or a few degrees in orbital angles), and quantify the number of consecutive transit observations necessary in order to obtain a reasonable opportunity of characterizing the unseen planet ({approx}>50 observations). Planets in or near period commensurabilities of the form p:q, where p {<=} 20 and q {<=} 3, produce distinct TTV signatures, regardless of whether the planets are actually locked in a mean motion resonance. We distinguish these systems from the secular systems in our explorations. Additionally, we find that computing the autocorrelation function of a TTV signal can provide a useful diagnostic for identifying possible orbits for additional planets and suggest that this method could aid integration of TTV signals in future studies of particular exosystems.

  19. Quantifying the Challenges of Detecting Unseen Planetary Companions with Transit Timing Variations

    NASA Astrophysics Data System (ADS)

    Veras, Dimitri; Ford, Eric B.; Payne, Matthew J.

    2011-02-01

    Both ground- and space-based transit observatories are poised to significantly increase the number of known transiting planets and the number of precisely measured transit times. The variation in a planet's transit times may be used to infer the presence of additional planets. Deducing the masses and orbital parameters of such planets from transit time variations (TTVs) alone is a rich and increasingly relevant dynamical problem. In this work, we evaluate the extent of the degeneracies in this process, systematically explore the dependence of TTV signals on several parameters, and provide phase space plots that could aid observers in planning future observations. Our explorations are focused on a likely-to-be prevalent situation: a known transiting short-period Neptune- or Jupiter-sized planet and a suspected external low-mass perturber on a nearly coplanar orbit. Through ~107 N-body simulations, we demonstrate how TTV signal amplitudes may vary by orders of magnitude due to slight variations in any one orbital parameter (10-3 AU in a semimajor axis, 0.005 in eccentricity, or a few degrees in orbital angles), and quantify the number of consecutive transit observations necessary in order to obtain a reasonable opportunity of characterizing the unseen planet (gsim50 observations). Planets in or near period commensurabilities of the form p:q, where p <= 20 and q <= 3, produce distinct TTV signatures, regardless of whether the planets are actually locked in a mean motion resonance. We distinguish these systems from the secular systems in our explorations. Additionally, we find that computing the autocorrelation function of a TTV signal can provide a useful diagnostic for identifying possible orbits for additional planets and suggest that this method could aid integration of TTV signals in future studies of particular exosystems.

  20. Unconventional Topological Phase Transition in Two-Dimensional Systems with Space-Time Inversion Symmetry.

    PubMed

    Ahn, Junyeong; Yang, Bohm-Jung

    2017-04-14

    We study a topological phase transition between a normal insulator and a quantum spin Hall insulator in two-dimensional (2D) systems with time-reversal and twofold rotation symmetries. Contrary to the case of ordinary time-reversal invariant systems, where a direct transition between two insulators is generally predicted, we find that the topological phase transition in systems with an additional twofold rotation symmetry is mediated by an emergent stable 2D Weyl semimetal phase between two insulators. Here the central role is played by the so-called space-time inversion symmetry, the combination of time-reversal and twofold rotation symmetries, which guarantees the quantization of the Berry phase around a 2D Weyl point even in the presence of strong spin-orbit coupling. Pair creation and pair annihilation of Weyl points accompanying partner exchange between different pairs induces a jump of a 2D Z_{2} topological invariant leading to a topological phase transition. According to our theory, the topological phase transition in HgTe/CdTe quantum well structure is mediated by a stable 2D Weyl semimetal phase because the quantum well, lacking inversion symmetry intrinsically, has twofold rotation about the growth direction. Namely, the HgTe/CdTe quantum well can show 2D Weyl semimetallic behavior within a small but finite interval in the thickness of HgTe layers between a normal insulator and a quantum spin Hall insulator. We also propose that few-layer black phosphorus under perpendicular electric field is another candidate system to observe the unconventional topological phase transition mechanism accompanied by the emerging 2D Weyl semimetal phase protected by space-time inversion symmetry.

  1. Unconventional Topological Phase Transition in Two-Dimensional Systems with Space-Time Inversion Symmetry

    NASA Astrophysics Data System (ADS)

    Ahn, Junyeong; Yang, Bohm-Jung

    2017-04-01

    We study a topological phase transition between a normal insulator and a quantum spin Hall insulator in two-dimensional (2D) systems with time-reversal and twofold rotation symmetries. Contrary to the case of ordinary time-reversal invariant systems, where a direct transition between two insulators is generally predicted, we find that the topological phase transition in systems with an additional twofold rotation symmetry is mediated by an emergent stable 2D Weyl semimetal phase between two insulators. Here the central role is played by the so-called space-time inversion symmetry, the combination of time-reversal and twofold rotation symmetries, which guarantees the quantization of the Berry phase around a 2D Weyl point even in the presence of strong spin-orbit coupling. Pair creation and pair annihilation of Weyl points accompanying partner exchange between different pairs induces a jump of a 2D Z2 topological invariant leading to a topological phase transition. According to our theory, the topological phase transition in HgTe /CdTe quantum well structure is mediated by a stable 2D Weyl semimetal phase because the quantum well, lacking inversion symmetry intrinsically, has twofold rotation about the growth direction. Namely, the HgTe /CdTe quantum well can show 2D Weyl semimetallic behavior within a small but finite interval in the thickness of HgTe layers between a normal insulator and a quantum spin Hall insulator. We also propose that few-layer black phosphorus under perpendicular electric field is another candidate system to observe the unconventional topological phase transition mechanism accompanied by the emerging 2D Weyl semimetal phase protected by space-time inversion symmetry.

  2. Gender Transitions in Later Life: The Significance of Time in Queer Aging

    PubMed Central

    Fabbre, Vanessa D.

    2014-01-01

    Concepts of time are ubiquitous in studies of aging. This article integrates an existential perspective on time with a notion of queer time based on the experiences of older transgender persons who contemplate or pursue a gender transition in later life. Interviews were conducted with male-to-female identified persons aged 50 years or older (N=22), along with participant observation at three national transgender conferences (N=170 hours). Interpretive analyses suggest that an awareness of “time left to live” and a feeling of “time served” play a significant role in later life development and help expand gerontological perspectives on time and queer aging. PMID:24798691

  3. Memory-induced diffusive-superdiffusive transition: Ensemble and time-averaged observables

    NASA Astrophysics Data System (ADS)

    Budini, Adrián A.

    2017-05-01

    The ensemble properties and time-averaged observables of a memory-induced diffusive-superdiffusive transition are studied. The model consists in a random walker whose transitions in a given direction depend on a weighted linear combination of the number of both right and left previous transitions. The diffusion process is nonstationary, and its probability develops the phenomenon of aging. Depending on the characteristic memory parameters, the ensemble behavior may be normal, superdiffusive, or ballistic. In contrast, the time-averaged mean squared displacement is equal to that of a normal undriven random walk, which renders the process nonergodic. In addition, and similarly to Lévy walks [Godec and Metzler, Phys. Rev. Lett. 110, 020603 (2013), 10.1103/PhysRevLett.110.020603], for trajectories of finite duration the time-averaged displacement apparently become random with properties that depend on the measurement time and also on the memory properties. These features are related to the nonstationary power-law decay of the transition probabilities to their stationary values. Time-averaged response to a bias is also calculated. In contrast with Lévy walks [Froemberg and Barkai, Phys. Rev. E 87, 030104(R) (2013), 10.1103/PhysRevE.87.030104], the response always vanishes asymptotically.

  4. The Real Time Disintegration of an Asteroid Transiting a White Dwarf

    NASA Astrophysics Data System (ADS)

    Xu, Siyi; Rappaport, Saul; DeVore, John; Ivanov, Valentin; Debes, John; Provencal, Judith; Vanderburg, Andrew; Croll, Bryce; Dufour, Patrick; Zuckerman, Ben

    2016-08-01

    There is strong evidence that an actively disintegrating asteroid is orbiting the white dwarf WD 1145+017. This scenario is supported by several observations, including: (i) transits from multiple objects within the white dwarf's tidal radius; (ii) infrared excess from a circumstellar dust disk; (iii) ubiquitous high-velocity absorption lines from circumstellar gas; (iv) a heavily polluted atmosphere from the accretion of the circumstellar material. We were awarded Spitzer DDT time to perform photometric observation simultaneously with a few other telescopes on March 29, 2016. Our preliminary analysis has returned the first detection of a color-dependent transit. Here, we propose to monitor this system over the next two years to understand the change of the transiting material as well as the possible change of the dust disk. This system provides a unique window to study the real time disintegration of an asteroid around a white dwarf.

  5. Transit times from rainfall to baseflow in headwater catchments estimated using tritium: the Ovens River, Australia

    NASA Astrophysics Data System (ADS)

    Cartwright, I.; Morgenstern, U.

    2015-06-01

    Headwater streams contribute a significant proportion of the total flow to many river systems, especially during summer low-flow periods. However, despite their importance, the time taken for water to travel through headwater catchments and into the streams (the transit time) is poorly constrained. Here, 3H activities of stream water are used to define transit times of water contributing to streams from the upper reaches of the Ovens River in southeast Australia at varying flow conditions. 3H activities of the stream water varied from 1.63 to 2.45 TU, which are below the average 3H activity of modern local rainfall (~3 TU). The highest 3H activities were recorded following higher winter flows and the lowest 3H activities were recorded at summer low-flow conditions. Variations of major ion concentrations and 3H activities with streamflow imply that different stores of water from within the catchment (e.g. from the soil or regolith) are mobilised during rainfall events rather than there being simple dilution of an older groundwater component by event water. Mean transit times calculated using an exponential-piston flow model range between 5 and 31 years and are higher at summer low-flow conditions. Mean transit times calculated using other flow models (e.g. exponential flow or dispersion) are similar. There are broad correlations between 3H activities and the percentage of rainfall exported from each catchment and between 3H activities and Na and Cl concentrations that allow first-order estimates of mean transit times in adjacent catchments or at different times in these catchments to be made. Water from the upper Ovens River has similar mean transit times to the headwater streams implying there is no significant input of old water from the alluvial gravels. The observation that the water contributing to the headwater streams in the Ovens catchment has a mean transit time of years to decades implies that these streams are buffered against rainfall variations on

  6. Transit times from rainfall to baseflow in headwater catchments estimated using tritium: the Ovens River, Australia

    NASA Astrophysics Data System (ADS)

    Cartwright, I.; Morgenstern, U.

    2015-09-01

    Headwater streams contribute a significant proportion of the total flow to many river systems, especially during summer low-flow periods. However, despite their importance, the time taken for water to travel through headwater catchments and into the streams (the transit time) is poorly understood. Here, 3H activities of stream water are used to define transit times of water contributing to streams from the upper reaches of the Ovens River in south-east Australia at varying flow conditions. 3H activities of the stream water varied from 1.63 to 2.45 TU, which are below the average 3H activity of modern local rainfall (2.85 to 2.99 TU). The highest 3H activities were recorded following higher winter flows and the lowest 3H activities were recorded at summer low-flow conditions. Variations of major ion concentrations and 3H activities with streamflow imply that different stores of water from within the catchment (e.g. from the soil or regolith) are mobilised during rainfall events rather than there being simple dilution of an older groundwater component by event water. Mean transit times calculated using an exponential-piston flow model range from 4 to 30 years and are higher at summer low-flow conditions. Mean transit times calculated using other flow models (e.g. exponential flow or dispersion) are similar. There are broad correlations between 3H activities and the percentage of rainfall exported from each catchment and between 3H activities and Na and Cl concentrations that allow first-order estimates of mean transit times in adjacent catchments or at different times in these catchments to be made. Water from the upper Ovens River has similar mean transit times to the headwater streams implying there is no significant input of old water from the alluvial gravels. The observation that the water contributing to the headwater streams in the Ovens catchment has a mean transit time of years to decades implies that these streams are buffered against rainfall variations on

  7. A Time Integration Algorithm Based on the State Transition Matrix for Structures with Time Varying and Nonlinear Properties

    NASA Technical Reports Server (NTRS)

    Bartels, Robert E.

    2003-01-01

    A variable order method of integrating the structural dynamics equations that is based on the state transition matrix has been developed. The method has been evaluated for linear time variant and nonlinear systems of equations. When the time variation of the system can be modeled exactly by a polynomial it produces nearly exact solutions for a wide range of time step sizes. Solutions of a model nonlinear dynamic response exhibiting chaotic behavior have been computed. Accuracy of the method has been demonstrated by comparison with solutions obtained by established methods.

  8. Transition time of nonlinear Landau-Zener model in adiabatic limit

    NASA Astrophysics Data System (ADS)

    Liu, Xuan-Zuo; Tian, Dong-Ping; Chong, Bo

    2016-06-01

    The impact of nonlinear interaction on the loop structure of lower energy level and on the time evolution curve of canonical momentum which corresponds to the lower eigenstate are analyzed respectively. We find that the curve changes from single-valued to multi-valued as nonlinear interaction grows. The fascinating part is that the time range delimited by turning points in the loop of energy level and the period between two inflexion points on the multi-valued part of the evolution curve of canonical momentum are the same. Therefore, we propose a characteristic time in the transition process of nonlinear Landau-Zener model in adiabatic limit. Last, the physical meaning of the transition time as a measure of how much time the system experiences a structural change which directly results in the breakdown of adiabaticity is discussed.

  9. Direct measurement of sequence-dependent transition path times and conformational diffusion in DNA duplex formation.

    PubMed

    Neupane, Krishna; Wang, Feng; Woodside, Michael T

    2017-02-07

    The conformational diffusion coefficient, D, sets the timescale for microscopic structural changes during folding transitions in biomolecules like nucleic acids and proteins. D encodes significant information about the folding dynamics such as the roughness of the energy landscape governing the folding and the level of internal friction in the molecule, but it is challenging to measure. The most sensitive measure of D is the time required to cross the energy barrier that dominates folding kinetics, known as the transition path time. To investigate the sequence dependence of D in DNA duplex formation, we measured individual transition paths from equilibrium folding trajectories of single DNA hairpins held under tension in high-resolution optical tweezers. Studying hairpins with the same helix length but with G:C base-pair content varying from 0 to 100%, we determined both the average time to cross the transition paths, τtp, and the distribution of individual transit times, PTP(t). We then estimated D from both τtp and PTP(t) from theories assuming one-dimensional diffusive motion over a harmonic barrier. τtp decreased roughly linearly with the G:C content of the hairpin helix, being 50% longer for hairpins with only A:T base pairs than for those with only G:C base pairs. Conversely, D increased linearly with helix G:C content, roughly doubling as the G:C content increased from 0 to 100%. These results reveal that G:C base pairs form faster than A:T base pairs because of faster conformational diffusion, possibly reflecting lower torsional barriers, and demonstrate the power of transition path measurements for elucidating the microscopic determinants of folding.

  10. The essential oil of Eucalyptus tereticornis and its constituents, α- and β-pinene, show accelerative properties on rat gastrointestinal transit.

    PubMed

    Jucá, Davi Matthews; da Silva, Moisés Tolentino Bento; Junior, Raimundo Campos; de Lima, Francisco José Batista; Okoba, Willy; Lahlou, Saad; de Oliveira, Ricardo Brandt; dos Santos, Armênio Aguiar; Magalhães, Pedro Jorge Caldas

    2011-01-01

    The essential oil of Eucalyptus tereticornis (EOET) has pharmacological activities but their effects on the gastrointestinal tract are yet unknown. It possesses α- and β-pinene as minor constituents, isomers largely used as food or drink additives. In this work, we studied their actions on gut motility. After feeding with a liquid test meal, conscious rats received perorally EOET, α-, or β-pinene, and the fractional dye retention was determined. EOET and its constituents decreased the gastric retention. In anesthetized rats, pinenes increased gastric tonus, while enhancing the meal progression in the small intestine of conscious rats. Both α- and β-pinene contracted gastric strips IN VITRO but relaxed the duodenum. Conversely, EOET relaxed both the gastric and duodenal strips. In conclusion, EOET accelerates the gastric emptying of liquid, and part of its action is attributed to the contrasting effects induced by α- and β-pinene on the gut.

  11. Measuring the Masses and Radii of Sub-Neptunes with Transit Timing Variations

    NASA Astrophysics Data System (ADS)

    Jontof-Hutter, Daniel; Lissauer, J. J.; Rowe, J. F.; Fabrycky, D.

    2013-10-01

    The bounty of sub-Neptunes discovered by Kepler enables us to study a regime in planetary size and mass that is absent from the Solar System. This regime includes a transition from rocky planets to those with substantial amounts of volatiles-- in either ice mantles or deep atmospheres. Characterizing these worlds by their bulk densities can probe this transition, and this requires mass and radius determinations. Outside our solar system, there is a small sample of planets with known masses and radii, mostly hot jupiters whose radii are known from transit depths, and whose masses are determined from radial velocity spectroscopy (RV). In the absence of mass determinations via RV observations, transit timing variations (TTVs) offer a chance to probe perturbations between planets that pass close to one another or are near resonance, and hence dynamical fits to observed transit times can measure planetary masses and orbital parameters. Such modelling can probe planetary masses at longer orbital periods than RV targets, although not without some challenges. For example, in modeling pairwise planetary perturbations, a degeneracy between eccentricity and mass exists that limits the accuracy of mass determinations. Nevertheless, in several compact multiplanet systems, fitting complex TTV signals can break the degeneracy, permitting useful mass determinations. The precision in measuring the radius of a transiting planet rests on the uncertainty in the stellar radius, which is typically ~10% for targets with spectral follow-up. With dynamical fits, however, solutions for the orbital parameters including the eccentricity vectors can, alongside the transit lightcurves, tightly constrain the stellar density and radius. Revisiting the six-planet system of Kepler-11, our dynamical fits to TTVs, alongside spectroscopic data on the host star, reduced the stellar and hence planetary radius uncertainties to just 2%, permitting useful planetary density determinations. In the case of

  12. Long-term transit timing monitoring and homogenous study of WASP-32

    NASA Astrophysics Data System (ADS)

    Sun, Lei-Lei; Gu, Sheng-Hong; Wang, Xiao-Bin; Collier Cameron, Andrew; Cao, Dong-Tao; Wang, Yi-Bo; Xiang, Yue; Hui, Ho-Keung; Kwok, Chi-Tai; Yeung, Bill; Leung, Kam-Cheung

    2015-01-01

    We report new photometric observations of the transiting exoplanetary system WASP-32 made by using CCD cameras at Yunnan Observatories and Ho Koon Nature Education cum Astronomical Centre, China from 2010 to 2012. Following our usual procedure, the observed data are corrected for systematic errors according to the coarse decorrelation and SYSREM algorithms so as to enhance the signal of the transit events. Combined with radial velocity data presented in the literature, our newly observed data and earlier photometric data in the literature are simultaneously analyzed to derive the physical parameters describing the system by employing the Markov chain Monte Carlo technique. The derived parameters are consistent with the result published in the original paper about WASP-32b, but the uncertainties of the new parameters are smaller than those in the original paper. Moreover, our modeling result supports a circular orbit for WASP-32b. Through the analysis of all available mid-transit times, we have refined the orbital period of WASP-32b; no evident transit timing variation is found in these transit events.

  13. Time-delay effects on the aging transition in a population of coupled oscillators.

    PubMed

    Thakur, Bhumika; Sharma, Devendra; Sen, Abhijit

    2014-10-01

    We investigate the influence of time-delayed coupling on the nature of the aging transition in a system of coupled oscillators that have a mix of active and inactive oscillators, where the aging transition is defined as the gradual loss of collective synchrony as the proportion of inactive oscillators is increased. We start from a simple model of two time-delay coupled Stuart-Landau oscillators that have identical frequencies but are located at different distances from the Hopf bifurcation point. A systematic numerical and analytic study delineates the dependence of the critical coupling strength (at which the system experiences total loss of synchrony) on time delay and the average distance of the system from the Hopf bifurcation point. We find that time delay can act to facilitate the aging transition by lowering the threshold coupling strength for amplitude death in the system. We then extend our study to larger systems of globally coupled active and inactive oscillators including an infinite system in the thermodynamic limit. Our model system and results can provide a useful paradigm for understanding the functional robustness of diverse physical and biological systems that are prone to aging transitions.

  14. The Importance of Timing of Transitions for Risk of Regular Smoking and Nicotine Dependence

    PubMed Central

    Dierker, Lisa; He, Jianping; Kalaydjian, Amanda; Swendsen, Joel; Degenhardt, Louisa; Glantz, Meyer; Conway, Kevin; Anthony, James; Chiu, Wai Tat; Sampson, Nancy A.; Kessler, Ronald; Merikangas, Kathleen

    2009-01-01

    Purpose To investigate the association between the timing and speed of transition among major smoking milestones (onset, weekly and daily smoking) and onset and recovery from nicotine dependence. Method Analyses are based on data from The National Comorbidity Survey-Replication (NCS-R), a nationally representative face-to-face household survey conducted between February 2001 and April 2003. Results Of those who had ever smoked (n=5,692), 71.3% had reached weekly smoking levels and 67.5% had reached daily smoking. Four in ten who had ever smoked met criteria for nicotine dependence. A shorter time since the onset of weekly and daily smoking was associated with a transition to both daily smoking and nicotine dependence, respectively. The risk for each smoking transition was highest within the year following the onset of the preceding milestone. Recovery was associated with a longer period of time between smoking initiation and the development of dependence and a later age of smoking onset. Conclusions These findings shed light on the clinical course of smoking and nicotine dependence. Given the importance of timing of smoking transitions, prevalence may be further reduced through intervention targeted at adolescents and young adults in the months most proximal to smoking initiation. PMID:18704617

  15. Dating Violence, Bullying, and Sexual Harassment: Longitudinal Profiles and Transitions over Time

    ERIC Educational Resources Information Center

    Miller, Shari; Williams, Jason; Cutbush, Stacey; Gibbs, Deborah; Clinton-Sherrod, Monique; Jones, Sarah

    2013-01-01

    Although there is growing recognition of the problem of dating violence, little is known about how it unfolds among young adolescents who are just beginning to date. This study examined classes (subgroups) and transitions between classes over three time points based on dating violence, bullying, and sexual harassment perpetration and victimization…

  16. VizieR Online Data Catalog: Transit timing variatio