Science.gov

Sample records for persisting mixed cryoglobulinemia

  1. [Heart failure as clinical onset of essential mixed cryoglobulinemia].

    PubMed

    Bragagni, G; Baldini, A; Bianconcini, M

    1998-01-01

    The case of a 58-year old man affected by heart failure on ischemic basis, as clinical onset of essential mixed cryoglobulinemia (EMC) is reported. Laboratory assays, ECG at rest and exercise electrocardiogram, echocardiogram, myocardial scintigraphy, cardiac catheterization with coronarography, hepatic, bone and kidney biopsies confirmed the diagnosis. Cases of primitive heart involvement are rarely reported and are, usually, due to myocardial infarction. Nevertheless in the published series of cases, heart failure is often coupled with EMC and, not seldom, is the cause of death. In the present case heart failure was the dominant element of clinical symptomatology and wasn't consequent to renal involvement or hypertension, but was sustained by a myocardial contractile deficiency, on ischemic basis, with undamaged coronary circle at angiography. Therefore heart failure was ascribed to an involvement of coronary microcirculation in the course of systemic vasculitis. PMID:9824990

  2. Cutaneous lesions and finger clubbing uncovering hypocomplementemic urticarial vasculitis and hepatitis C with mixed cryoglobulinemia.

    PubMed

    Pinto-Almeida, Teresa; Caetano, Mónica; Alves, Rosário; Selores, Manuela

    2013-01-01

    Urticarial vasculitis is a rare clinicopathologic entity characterized by urticarial lesions that persist for more than 24 hours and histologic features of leukocytoclastic vasculitis. Patients can be divided into normocomplementemic or hypocomplementemic. The authors report the case of a healthy 49-year-old woman with a 1-year history of highly pruritic generalized cutaneous lesions and finger clubbing. Laboratory tests together with histopathologic examination allowed the diagnosis of hypocomplementemic urticarial vasculitis, chronic hepatitis C and type II mixed cryoglobulinemia. The patient started symptomatic treatment and was referred to a gastroenterologist for management of the hepatitis C, with progressive improvement of the skin condition. The development of hypocomplementemic urticarial vasculitis in the context of chronic hepatitis C is exceedingly rare and possible pathogenic mechanisms are discussed. PMID:24474109

  3. Catastrophic multiple organ ischemia due to an anti-Pr cold agglutinin developing in a patient with mixed cryoglobulinemia after treatment with rituximab.

    PubMed

    Ruch, Joshua; McMahon, Brandon; Ramsey, Glenn; Kwaan, Hau C

    2009-02-01

    Cold agglutinin disease occurring with cryoglobulinemia is a rare occurrence. Here, we report a patient with mixed cryoglobulinemia that was treated with rituximab and, after response, developed an anti-Pr cold agglutinin that manifested with hemolysis and microvascular occlusion causing mesenteric ischemia and cerebral infarction. Unlike previous reports of patients with cryoglobulinemia and cold agglutinin disease, our patient did not have a detectable cryoprecipitate when his cold agglutinin manifested. PMID:19097173

  4. A Rare Cause of Unilateral Central Retinal Vein Occlusion in a Young Patient: Type III Mixed Cryoglobulinemia

    PubMed Central

    Sekeroglu, Mehmet Ali; Anayol, Mustafa Alpaslan; Yilmazbas, Pelin

    2016-01-01

    Purpose. To report a young male with unilateral central retinal vein occlusion (CRVO) associated with cryoglobulinemia. Case Presentation. A 33-year-old male without any known systemic or ocular disorder was admitted to our clinic with a complaint of visual loss for three days in his left eye. Based on the clinical, laboratory, and ophthalmological assessments, we diagnosed this case as type III mixed cryoglobulinemia with unilateral CRVO with macular edema. For treatment, two intravitreal ranibizumab injections were administered monthly and oral prednisone (64 mg/day) was begun. Subsequently, cryoglobulins became undetectable, macular edema decreased, and the visual acuity improved to 20/32 over an 8-week period. At 24 weeks, the patient's visual acuity remained 20/32 and no recurrence was observed while the patient was still on prednisone (16 mg/day). Conclusion. Cryoglobulinemia should be considered in the differential diagnosis of the patients with CRVO. PMID:27418988

  5. Mixed cryoglobulinemia-associated Sjögren’s syndrome leading to spontaneous rupture of the kidney: a case report

    PubMed Central

    Haddiya, Intissar; Hamzaoui, Hakim; Alhamany, Zitouna; Berkchi, Fatime-zohra; Rhou, Hakima; Benamar, Loubna; Ouzeddoun, Naima; Bayahia, Rabea

    2016-01-01

    Background Spontaneous rupture of the kidney is uncommon and is mainly caused by renal tumors. Only a few cases are caused by vasculitis. We report here the first case of spontaneous rupture of kidney resulting from mixed cryoglobulinemia. Case presentation A 44-year-old man presented with sudden onset of fever, acute pulmonary edema, left flank abdominal pain unassociated with trauma, and rapidly progressive renal failure requiring dialysis. Computed tomography of the abdomen revealed a large perirenal hematoma of the left kidney. During conservative surgery, the patient underwent renal biopsy that showed renal vasculitis and membranoproliferative glomerulonephritis with intracapillary microthrombi. Tests were positive for mixed cryoglobulinemia caused by Sjögren’s syndrome. The patient was better after immunosuppressive therapy, with the disappearance of clinical symptoms and the recovery of baseline renal function. Conclusion We report on this case and discuss a possible link between spontaneous rupture of kidney and mixed cryoglobulinemia-associated Sjögren’s syndrome. PMID:27042145

  6. Incidence of thyroid disorders in mixed cryoglobulinemia: Results from a longitudinal follow-up.

    PubMed

    Fallahi, Poupak; Ferrari, Silvia Martina; Ruffilli, Ilaria; Elia, Giusy; Giuggioli, Dilia; Colaci, Michele; Ferri, Clodoveo; Antonelli, Alessandro

    2016-07-01

    No study has evaluated the incidence of new cases of thyroid autoimmunity (AT) and dysfunction (TD) in hepatitis C-associated mixed cryoglobulinemia (MC) patients. We aimed to evaluate the incidence of new cases of AT and TD in a wide group of MC patients vs. age- and gender-matched controls from the same geographic area. After exclusion of MC patients with TD at the initial evaluation, the appearance of new cases of TD was evaluated in 112 MC patients and 112 matched controls, with similar iodine intake (median follow-up 67months in MC vs. 78 in controls). A high incidence (P<0.05) of new cases of hypothyroidism, TD, anti-thyroperoxidase antibody (AbTPO) positivity, appearance of a hypoechoic thyroid pattern, and thyroid autoimmunity in MC patients vs. controls was shown. A logistic regression analysis showed that in MC, the appearance of hypothyroidism was related to female gender, a borderline high initial thyroid-stimulating hormone (TSH), AbTPO positivity, a hypoechoic, and small thyroid. In conclusion, we show a high incidence of new cases of AT and TD in MC patients. MC patients at high risk (female gender, a borderline high initial TSH, AbTPO positivity, a hypoechoic, and small thyroid) should have periodically thyroid function follow-up. PMID:26970485

  7. Vitamin D pathway gene polymorphisms as predictors of hepatitis C virus-related mixed cryoglobulinemia.

    PubMed

    Cusato, Jessica; Boglione, Lucio; De Nicolò, Amedeo; Cardellino, Chiara Simona; Carcieri, Chiara; Cariti, Giuseppe; Di Perri, Giovanni; D'Avolio, Antonio

    2016-06-01

    Mixed cryoglobulinemia (MC) is the most frequent extrahepatic hepatitis C virus (HCV) complication. Vitamin D is a modulator of several biological processes, including immune and skeletal systems and MC presence and systemic vasculitis were associated independently with low levels of vitamin D. Considering the impact of vitamin D, we aimed to evaluate the role of some single nucleotide polymorphisms (SNPs) of vitamin D pathway genes in the prediction of MC in HCV patients treated with pegylated interferon and ribavirin. We investigated SNPs in IL-28B, CYP27B1, CYP27A1, CYP24A1, VDBP, and VDR genes through real-time PCR. VDR gene SNPs were related to baseline viral load: VDR BsmI AA (P=0.018), TaqI CC (P=0.009), and ApaI AA (P=0.004) showed a lower baseline HCV count. Among vitamin D pathway gene polymorphisms, VDR FokI T>C was a factor associated with the presence of MC in the study population (P=0.011): related to C allele carriers (TT vs. TC/CC), we obtained a P-value of 0.003. In the logistic regression analysis to assess which demographic, clinical, or genetic factors could predict the presence of cryoglobulin, the TT/CC IL-28B rs8099917/rs12979860 haplotype [P<0.001; odds ratio (OR) 3.516 (1.951-6.336)], baseline viral load [P<0.001; OR 1.000 (0.999-1.001)], and VDR FokI TC/CC genotypes [0.044; OR 0.463 (0.218-0.981)] remained in the final regression model. These data could help physicians identify patients with a higher probability of developing MC extrahepatic complications. PMID:27139837

  8. Pulmonary Extranodal Marginal Zone Lymphoma with Macroglobulinemia and Mixed Cryoglobulinemia Developed in a Patient with Chronic Hepatitis C.

    PubMed

    Min, Chisun; Higuchi, Takakazu; Koyamada, Ryosuke; Yamaguchi, Norihiro; Okada, Sadamu

    2015-01-01

    We report a 65-year-old woman with a chronic hepatitis C virus infection who developed pulmonary extranodal marginal zone lymphoma (EMZL) of mucosa-associated lymphoid tissues complicated with macroglobulinemia and mixed cryoglobulinemia. She was treated with immunochemotherapy which resulted in the reduction of both the tumors and the serum immunoglobulin (Ig) M level. This case exemplifies an extensive stimulation upon immune system with derangement in the production of immunoglobulines associated with EMZL, and suggests that it is necessary to consider the possibility of B-cell lymphoma when IgM paraprotein is detected. PMID:26278303

  9. Leukocytoclastic vasculitis in a patient with type 1 cryoglobulinemia.

    PubMed

    Liu, Paul Y; Prete, Pamela E; Kukes, Gary

    2011-01-01

    Cutaneous manifestations of type 1 cryoglobulinemia are usually related to vascular occlusion by noninflammatory thrombosis; rarely is leukocytoclastic vasculitis seen in type 1 cryoglobulinemia. We report the case of a 64-year-old male who presented with isolated cutaneous leukocytoclastic vasculitis that was initially attributed to essential mixed cryoglobulinemia after thorough diagnostic evaluation. A lack of adequate clinical response to therapy prompted further investigation, including cryoprecipitate electrophoresis and immunofixation, which revealed an IgM kappa monoclonal gammopathy consistent with type 1 cryoglobulinemia. A renewed search for an underlying malignancy led to the discovery of early Waldenstrom's macroglobulinemia. Although leukocytoclastic vasculitis is more characteristic of mixed cryoglobulinemia, it can be a presenting manifestation of type 1 cryoglobulinemia. PMID:22937435

  10. Thromboangiitis obliterans with cryoglobulinemia.

    PubMed

    Owlia, Mohammad Bagher; Mehrpoor, Golbarg

    2014-11-01

    Thromboangiitis obliterans (TAO), or Buerger's disease, is a vascular occlusive disease associated with cigarette smoking. It typically affects medium sized vessels of extremities. Basic pathology of TAO is described to be endothelial activation with highly inflammatory intraluminal thrombosis preserving internal elastic membrane. Cryoglobulins are immunoglobulins that precipitate in the cold and dissolve on re-warming. Cryoglobulinemic vasculitis is a typical small vessel disease associated with cryoglobulinemia commonly bearing typical purpuric skin lesions. An association of TAO with cryoglobulinemia is not reported yet. We report a 34-year-old male heavy cigarette smoker seen for extremity pain and cyanosis of left little finger along with skin rashes characteristic of small vessel disease. Initial presentation of his symptoms at winter and unusual purpuric skin lesions led to search for cold-agglutinating globulins in his plasma. He had severe cryoglobulinemia while the other laboratory tests were normal. TAO associated with cryoglobulinemia merges as a possibility. PMID:25404449

  11. [Renal involvement during type 1 cryoglobulinemia].

    PubMed

    Zaidan, Mohamad; Plasse, Florent; Rabant, Marion; Javaugue, Vincent; Knebelmann, Bertrand; Alyanakian, Marie-Alexandra; Joly, Dominique; Nochy, Dominique; Bridoux, Frank

    2016-04-01

    Cryoglobulins are circulating immunoglobulins that precipitate with cold temperature and dissolve with rewarming. Type 1 cryoglobulinemia is composed of a single monoclonal immunoglobulin and is associated with renal involvement in up to 40% of cases. Type 1 cryoglobulinemia is related to an underlying B-cell haematological malignancy in 60% of patients. In the remaining cases, in the absence of criteria for malignancy, the diagnosis of monoclonal gammopathy of renal significance should be established. The clinical and biological setting and histological features of type 1 cryoglobulinemia are globally similar to those of mixed cryoglobulinemia. In case of haematological malignancy, the treatment is guided by the nature of the underlying disease, and aims at inducing haematological remission, which is necessary for the renal response. The management of monoclonal gammopathy of renal significance has been clarified by an international consensus group and is based on the nature of the underlying clone. In case of monoclonal cryoglobulinemia associated with a plasma-cell clone (IgG or IgA), the treatment is based on the combination of bortezomib, cyclophosphamide and dexamethasone. In case of IgM monoclonal cryoglobulinemia, the treatment is similar to that of Waldenström macroglobulinemia, and is based on rituximab. The clinical course of renal monoclonal cryoglobulinemia is intimately associated with the haematological response, and is usually favourable. PMID:26972092

  12. Hepatic and Mesenteric Vasculitis as Presenting Manifestation of Mixed Cryoglobulinemia Related to Chronic Hepatitis C Virus Infection in a Female Patient.

    PubMed

    Calle Toro, Juan S; Davalos, Diana M; Charry, Jose D; Arrunategi, Ana M; Tobon, Gabriel

    2016-06-01

    Approximately 80% of patients with hepatitis C virus infection develop chronic liver disease as cirrhosis, and 40% develop autoimmune complications as mixed cryoglobulinemia (MC). Gastrointestinal involvement in MC is rare, and even more so is hepatic involvement. We report a case of an 87-year-old woman with a 10-year history of blood transfusion-acquired hepatitis C virus infection, without treatment. She consulted the emergency department for diffuse abdominal pain, associated with vomiting. After 2 weeks of hospitalization in the intensive care unit, a diagnosis of MC was made; cirrhosis and secondary mesenteric and hepatic vasculitis were confirmed by a diagnostic laparoscopy. Unfortunately the condition of the patient worsened with sepsis and resulted in death in the fourth week from admission. This case highlights the importance of having in mind gastrointestinal tract vasculitis as a medical cause of abdominal pain in patients with chronic hepatitis C virus infection and using data laboratory tests, images, and histopathologic studies to aid with the diagnosis. PMID:27219310

  13. Membranoproliferative glomerulonephritis with essential cryoglobulinemia

    PubMed Central

    Satish, S.; Rajesh, R.; George, K.; Elango, E. M.; Unni, V. N.

    2008-01-01

    Cryoglobulinemia is an uncommon cause of renal disease and often occurs in patients with hepatitis C virus (HCV) infection. We report a case of membranoproliferative glomerulonephritis in a patient with cryoglobulinemia, which was not associated with HCV infection or any identifiable etiology. PMID:20142909

  14. Cryoglobulinemia

    MedlinePlus

    ... is also used. In this his procedure, blood plasma is taken out of blood circulation and abnormal cryoglobulin antibody proteins are removed. The plasma is replaced by fluid, protein, or donated plasma. ...

  15. Cryoglobulinemia

    MedlinePlus

    ... high if hepatitis C is present Rheumatoid factor -- positive in types II and III Skin biopsy -- may show inflammation in blood vessels, vasculitis Protein electrophoresis - blood -- may show an abnormal antibody protein Urinalysis -- may show blood in the urine if the ...

  16. Cryoglobulinemia

    MedlinePlus

    ... the VF E-News HERE A A A Youtube LinkedIn Twitter Facebook Takayasu’s Arteritis Webinar + Vasculitis Behcet’s ... Book Vasculitis Terms A – Z VF Medical Consultants YouTube Education Videos YouTube Education Videos produced by Alliance ...

  17. Safety and efficacy of rituximab treatment for vasculitis in hepatitis B virus-associated type II cryoglobulinemia: a case report

    PubMed Central

    2012-01-01

    Introduction Systemic B-cell depletion and clinical remission of the systemic effects of cryoglobulins have already been achieved using rituximab in hepatitis C virus-positive immunocompetent patients. Conversely, to the best of our knowledge there are no reports in the literature regarding the use of rituximab in hepatitis B virus-associated cryoglobulinemia. Case presentation We report here the case of a 60-year-old Caucasian man who presented with hepatitis B virus-associated type II cryoglobulinemia with severe multisystem disease, including membranoproliferative glomerulonephritis with acute renal failure. The vasculitis was refractory to conventional and antiviral therapy but rituximab use led to a fall in cryoglobulin levels and disease control. The B-cell depletion was safe and efficient to induce a complete remission of the disease. Conclusion Our case highlights the benefit and the efficacy of rituximab in association with antiviral therapy in small vessel vasculitis related to hepatitis B virus-associated mixed cryoglobulinemia. PMID:22284897

  18. Idiopathic Nonviral Cryoglobulinemia Treated Successfully With Rituximab.

    PubMed

    Kamel, Mahmoud; Thajudeen, Bijin; Bracamonte, Erika; Madhrira, Machaiah

    2016-01-01

    Cryoglobulinemia is a systemic inflammatory syndrome that generally involves small-to-medium vessel vasculitis due to cryoglobulin-containing immune complexes. The therapeutic management of idiopathic cryoglobulinemic vasculitis has yet to be defined because no study has evaluated the best strategies. However, treatment of severe vasculitis is traditionally based on a combination of corticosteroids and immunosuppressants or plasmapheresis, and more recently rituximab. We report a case of 77-year-old female patient diagnosed with idiopathic cryoglobulinemia, treated successfully with 6 months prednisone tapering and 2 doses of rituximab (1 g each dose). After receiving the above-mentioned treatment, her creatinine went back to normal with resolution of proteinuria and hematuria, normalization of serum complements, and significant improvement in her clinical picture. We conclude that rituximab could be an effective treatment for idiopathic cryoglobulnemia. PMID:24914502

  19. Successful Treatment of Pyoderma Gangrenosum with Cryoglobulinemia and Hepatitis C

    PubMed Central

    Pourmorteza, Mohsen; Tawadros, Fady; Bader, Gilbert; Al-Tarawneh, Mohammad; Cook, Emilie; Shams, Wael; Young, Mark

    2016-01-01

    Patient: Male, 68 Final Diagnosis: Pyoderma gangrenosum Symptoms: Worsening lower extremity wound Medication: — Clinical Procedure: — Specialty: Infectious Diseases Objective: Rare disease Background: Pyoderma gangrenosum is a rare, ulcerative cutaneous condition that was first described by Brocq in 1916. This diagnosis is quite challenging as the histopathological findings are nonspecific. Pyoderma gangrenosum is usually associated with inflammatory bowel disease, leukemia, and hepatitis C. We describe a rare clinical case of a patient with hepatitis C (HCV), mixed cryoglubinemia, and pyoderma gangrenosum, which was successfully treated with prednisone in combination with the new antiviral medication ledipasvir/sofosbuvir. Case Report: A 68-year-old male with a history of untreated HCV presented to the clinic with a left lower extremity ulcer that had progressively worsened over 4 days after the patient sustained a minor trauma to the left lower extremity. Examination revealed a 2×3 cm purulent ulcer with an erythematous rim on medial aspect of his left lower leg. HCV viral load and genotype analysis revealed genotype 1A with polymerase chain reaction (PCR) showing viral counts of 9,506,048 and cryoglobulinemia. With a worsening and enlarging erythematous ulcer and failure of IV antibiotic therapy, the patient underwent skin biopsy, which showed acanthotic epidermis with superficial and deep perivascular lymphoplasmacytic dermatitis admixed with mild neutrophilic infiltrate. The patient was subsequently started on ledipasvir/sofosbuvir and prednisone with a high suspicion of pyoderma gangrenosum. At one-month follow-up at the hepatology clinic, the patient demonstrated a near resolution of the lower extremity ulcer with undetectable viral load. Conclusions: Pyoderma gangrenosum is an inflammatory process of unknown etiology, and establishing the correct diagnosis can be a difficult task. For this reason it is prudent for clinicians to consider Pyoderma

  20. Successful Treatment of Pyoderma Gangrenosum with Cryoglobulinemia and Hepatitis C.

    PubMed

    Pourmorteza, Mohsen; Tawadros, Fady; Bader, Gilbert; Al-Tarawneh, Mohamed; Cook, Emilie; Shams, Wael; Young, Mark

    2016-01-01

    BACKGROUND Pyoderma gangrenosum is a rare, ulcerative cutaneous condition that was first described by Brocq in 1916. This diagnosis is quite challenging as the histopathological findings are nonspecific. Pyoderma gangrenosum is usually associated with inflammatory bowel disease, leukemia, and hepatitis C. We describe a rare clinical case of a patient with hepatitis C (HCV), mixed cryoglubinemia, and pyoderma gangrenosum, which was successfully treated with prednisone in combination with the new antiviral medication ledipasvir/sofosbuvir. CASE REPORT A 68-year-old male with a history of untreated HCV presented to the clinic with a left lower extremity ulcer that had progressively worsened over 4 days after the patient sustained a minor trauma to the left lower extremity. Examination revealed a 2×3 cm purulent ulcer with an erythematous rim on medial aspect of his left lower leg. HCV viral load and genotype analysis revealed genotype 1A with polymerase chain reaction (PCR) showing viral counts of 9,506,048 and cryoglobulinemia. With a worsening and enlarging erythematous ulcer and failure of IV antibiotic therapy, the patient underwent skin biopsy, which showed acanthotic epidermis with superficial and deep perivascular lymphoplasmacytic dermatitis admixed with mild neutrophilic infiltrate. The patient was subsequently started on ledipasvir/sofosbuvir and prednisone with a high suspicion of pyoderma gangrenosum. At one-month follow-up at the hepatology clinic, the patient demonstrated a near resolution of the lower extremity ulcer with undetectable viral load. CONCLUSIONS Pyoderma gangrenosum is an inflammatory process of unknown etiology, and establishing the correct diagnosis can be a difficult task. For this reason it is prudent for clinicians to consider Pyoderma gangrenosum in their differential diagnosis, especially in the setting of a nonhealing surgical wound or skin infection. PMID:27345376

  1. Secondary Science Teachers' Beliefs and Persistence: A Longitudinal Mixed-Methods Study

    ERIC Educational Resources Information Center

    Wong, Sissy S.; Luft, Julie A.

    2015-01-01

    While many studies focus on why teachers leave the classroom, there remains a need to study why teachers persist in teaching. One area to study is the beliefs of teachers, which may impact persistence in the field. This 5-year mixed-methods study explored whether 35 beginning secondary science teachers' beliefs were related to their persistence in…

  2. Persistence of rotationally grazed red clover in mixed stands.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Red Clover (Trifolium pratense) is an important forage legume in grazing pastures. Historically red clover was limited by its comparatively lower stand persistence in hay and grazed systems. Smith (2000) demonstrated increased persistence under hay management achieved through over 30 years of bree...

  3. Secondary Science Teachers' Beliefs and Persistence: A Longitudinal Mixed-Methods Study

    NASA Astrophysics Data System (ADS)

    Wong, Sissy S.; Luft, Julie A.

    2015-11-01

    While many studies focus on why teachers leave the classroom, there remains a need to study why teachers persist in teaching. One area to study is the beliefs of teachers, which may impact persistence in the field. This 5-year mixed-methods study explored whether 35 beginning secondary science teachers' beliefs were related to their persistence in teaching. Quantitative analysis of the teachers' responses to annual semi-structured interviews revealed that teachers with more student-centered beliefs were more likely to persist at the end of the third year of teaching. Additionally, the teaching beliefs of teachers were more teacher-centered, while the learning beliefs of teachers were more student-centered. A case study of one persisting teacher and one non-persisting teacher revealed that personal experiences and knowledge impacted beliefs about teaching and learning. Bruce, who had extensive inquiry-based school experiences, believed in teaching via student-centered methods. Oscar, who underwent mostly direct instruction during his school experiences, believed in teacher-centered instruction and focused on classroom management. This longitudinal study contributes to the field of science education by examining beginning secondary science teacher persistence over time. Implications from this study call for challenging teacher beliefs during the induction period, proper placement of new teachers into their first teaching positions, and understanding the impact of prior experiences on teachers' beliefs.

  4. Stories of staying and leaving: A mixed methods analysis of biology undergraduate choice, persistence, and departure

    NASA Astrophysics Data System (ADS)

    Lang, Sarah Adrienne

    Using a sequential, explanatory mixed methods design, this dissertation study compared students who persist in the biology major (persisters) with students who leave the biology major (switchers) in terms of how their pre-college experiences, college biology experiences, and biology performance figured into their choice of biology and their persistence in or departure from the biology major. This study combined (1) quantitative comparisons of biology persisters and switchers via a questionnaire developed for the study and survival analysis of a larger population of biology freshmen with (2) qualitative comparison of biology switchers and persisters via semi-structured life story interviews and homogenous focus groups. 319 students (207 persisters and 112 switchers) participated in the questionnaire and 36 students (20 persisters and 16 switchers) participated in life story and focus group interviews. All participants were undergraduates who entered The University of Texas at Austin as biology freshmen in the fall semesters of 2000 through 2004. Findings of this study suggest: (1) Regardless of eventual major, biology students enter college with generally the same suite of experiences, sources of personal encouragement, and reasons for choosing the biology major; (2) Despite the fact that they have also had poor experiences in the major, biology persisters do not actively decide to stay in the biology major; they simply do not leave; (3) Based upon survival analysis, biology students are most at-risk of leaving the biology major during the first two years of college and if they are African-American or Latino, women, or seeking a Bachelor of Arts degree (rather than a Bachelor of Science); (4) Biology switchers do not leave biology due to preference for other disciplines; they leave due to difficulties or dissatisfaction with aspects of the biology major, including their courses, faculty, and peers; (5) Biology performance has a differential effect on persistence in

  5. Successful use of cryocrit for monitoring response to therapeutic plasma exchange in type 1 cryoglobulinemia.

    PubMed

    Olson, Nicholas; Yerrabothala, Swaroopa; Dunbar, Nancy

    2016-08-01

    Waldenstrom macroglobulinemia (WM) is a clinical syndrome that is defined as lymphoplasmacytic lymphoma with bone marrow involvement and IgM monoclonal gammopathy of any level. In some instances WM can result in a type I cryoglobulinemia with very high cryocrits, which is unusual in type II and III cryoglobulinemia. We describe a case of an 80 year old male with WM, severe type I cryoglobulinemia, and an extremely elevated cryocrit (69%). Over the course of five weeks we performed nine therapeutic plasma exchanges (TPE), and after seven treatments his cryocrit had decreased to 6% with improvement in his symptoms. By monitoring his cryocrit throughout his TPE sessions, we were able to assess his response to treatment, determine the ideal length of treatment in addition to his symptomatic improvement. J. Clin. Apheresis 31:403-404, 2016. © 2015 Wiley Periodicals, Inc. PMID:26194475

  6. Cryoglobulinemia as an Initial Manifestation of Underlying Hematological Malignancy: A Rare Occurrence in India

    PubMed Central

    Kumar, Narender; Das, Reena; Chandra, Dinesh; Malhotra, Pankaj

    2014-01-01

    Cryoglobulinemias rarely been reported from India even though associated conditions such as hepatitis C infection, rheumatoid arthritis and plasma cell dyscrasias, etc., are common occurrences. In many regions of the country, temperatures in winter can be conducive to the precipitation of cryoglobulins, yet epidemiology of the disease suggests that it is a common condition in the west. We encountered a 68-year-old-male patient who presented with a history of headache off and on along with hepatosplenomegaly. The rare occurrence of cryoglobulinemia in our setting can delay the diagnosis, as happened in our case, since the index of suspicion of clinicians and laboratory personnel is low. We are reporting this case because of the rarity and protean clinical manifestations of cryoglobulinemia. PMID:25328341

  7. An Unusual Case of HCV Negative Cryoglobulinemia Presenting as Symmetrical Peripheral Gangrene

    PubMed Central

    Meher, Lalit Kumar; Behera, Samir Kumar; Nayak, Sachidananda; Tripathy, Sujit Kumar

    2016-01-01

    Cryoglobulins are monoclonal or polyclonal immunoglobulins that undergo reversible precipitation at low temperatures. Cryoglobulinemia is associated with HCV infection in more than 90% cases, the remaining 10% being called as Essential Cryoglobulinemia which is generally associated with a severe course and suboptimal response to conventional therapies. As the digital vessels are more prone to colder temperatures, hyperviscosity in those vessels can initiate local thrombosis and may manifest as ischemic ulceration and gangrene. We report here a very unusual case of HCV negative cryoglobulinemic vasculitis presenting as symmetrical peripheral gangrene of fingers and toes. PMID:27190872

  8. Coronary artery bypass grafting in a patient with active idiopathic cryoglobulinemia: revisiting the issue

    PubMed Central

    Fakih, Hafiz Abdul Moiz; Elueze, Emmanuel; Vij, Rajiv

    2016-01-01

    Background Cryoglobulinemia is a cold-reactive autoimmune disease. It is of distinctive importance in cardiac surgery because of the use of hypothermic cardiopulmonary bypass (CPB). Cryoglobulins, which activate at variable levels of hypothermia, can cause precipitation during surgery leading to possibly severe leukocytoclastic or necrotizing vasculitis, clinically manifested as ischemic events, such as cutaneous ulcerations, glomerulonephritis, arthritis, or peripheral neuropathies among the most reported associated comorbidities. Management of CPB and systemic protection in this rare but unique scenario requires individualized planning. We report the case of a patient with active cryoglobulinemia who was preoperatively managed with plasmapheresis. He underwent hypothermic coronary bypass with no precipitation and flare during and after surgery. Case presentation We describe the case of a 59-year-old Caucasian male with clinically significant idiopathic cryoglobulinemia and history of recurrent skin lesions and toe amputations secondary to cold exposure. He presented with 2-h duration of chest pain and new onset atrial fibrillation. After cardiac catheterization, a diagnosis of three-vessel coronary artery disease was established and coronary artery bypass grafting (CABG) was scheduled. Because of a high risk of flare-up during surgery, the patient was preemptively treated with two sessions of plasmapheresis before bypass. He then underwent hypothermic CABG. The pre- and perioperative course was unremarkable without any clinical evidence of precipitation. The patient was discharged on day 6 postoperatively without any complications. Conclusion Preoperative plasmapheresis before hypothermic coronary bypass can prevent fatal cryoglobulinemia-related complications in patients with active disease. PMID:26908383

  9. Persistent dopants and phase segregation in organolead mixed-halide perovskites

    DOE PAGESBeta

    Rosales, Bryan A.; Men, Long; Cady, Sarah D.; Hanrahan, Michael P.; Rossini, Aaron J.; Vela, Javier

    2016-07-25

    Organolead mixed-halide perovskites such as CH3NH3PbX3–aX'a (X, X' = I, Br, Cl) are interesting semiconductors because of their low cost, high photovoltaic power conversion efficiencies, enhanced moisture stability, and band gap tunability. Using a combination of optical absorption spectroscopy, powder X-ray diffraction (XRD), and, for the first time, 207Pb solid state nuclear magnetic resonance (ssNMR), we probe the extent of alloying and phase segregation in these materials. Because 207Pb ssNMR chemical shifts are highly sensitive to local coordination and electronic structure, and vary linearly with halogen electronegativity and band gap, this technique can provide the true chemical speciation and compositionmore » of organolead mixed-halide perovskites. We specifically investigate samples made by three different preparative methods: solution phase synthesis, thermal annealing, and solid phase synthesis. 207Pb ssNMR reveals that nonstoichiometric dopants and semicrystalline phases are prevalent in samples made by solution phase synthesis. We show that these nanodomains are persistent after thermal annealing up to 200 °C. Further, a novel solid phase synthesis that starts from the parent, single-halide perovskites can suppress phase segregation but not the formation of dopants. Our observations are consistent with the presence of miscibility gaps and spontaneous spinodal decomposition of the mixed-halide perovskites at room temperature. This underscores how strongly different synthetic procedures impact the nanostructuring and composition of organolead halide perovskites. In conclusion, better optoelectronic properties and improved device stability and performance may be achieved through careful manipulation of the different phases and nanodomains present in these materials.« less

  10. Students' Persistence in a Distributed Doctoral Program in Educational Leadership in Higher Education: A Mixed Methods Study

    ERIC Educational Resources Information Center

    Ivankova, Nataliya V.; Stick, Sheldon L.

    2007-01-01

    The purpose of this mixed methods sequential explanatory study was to identify factors contributing to students' persistence in the University of Nebraska-Lincoln Distributed Doctoral Program in Educational Leadership in Higher Education by obtaining quantitative results from surveying 278 current and former students and then following up with…

  11. The Federal Transformation Intervention Model in Persistently Lowest Achieving High Schools: A Mixed-Methods Study

    ERIC Educational Resources Information Center

    Le Patner, Michelle B.

    2012-01-01

    This study examined the American Recovery and Reinvestment Act federal mandate of the Transformation Intervention Model (TIM) outlined by the School Improvement Grant, which was designed to turn around persistently lowest achieving schools. The study was conducted in four high schools in a large Southern California urban district that selected the…

  12. Variable but persistent coexistence of Prochlorococcus ecotypes along temperature gradients in the ocean's surface mixed layer.

    PubMed

    Chandler, Jeremy W; Lin, Yajuan; Gainer, P Jackson; Post, Anton F; Johnson, Zackary I; Zinser, Erik R

    2016-04-01

    The vast majority of the phytoplankton communities in surface mixed layer of the oligotrophic ocean are numerically dominated by one of two ecotypes of Prochlorococcus, eMIT9312 or eMED4. In this study, we surveyed large latitudinal transects in the Atlantic and Pacific Ocean to determine if these ecotypes discretely partition the surface mixed layer niche, or if populations exist as a continuum along key environmental gradients, particularly temperature. Transitions of dominance occurred at approximately 19-21°C, with the eMED4 ecotype dominating the colder, and eMIT9312 ecotype dominating the warmer regions. Within these zones of regional dominance, however, the minority ecotype was not competed to extinction. Rather, a robust log-linear relationship between ecotype ratio and temperature characterized this stabilized coexistence: for every 2.5°C increase in temperature, the eMIT9312:eMED4 ratio increased by an order of magnitude. This relationship was observed in both quantitative polymerase chain reaction and in pyrosequencing assays. Water column stratification also contributed to the ecotype ratio along the basin-scale transects, but to a lesser extent. Finally, instances where the ratio of the eMED4 and eMIT9312 abundances did not correlate well with temperature were identified. Such occurrences are likely due to changes in water temperatures outpacing changes in community structure. PMID:26743532

  13. The occurrence and persistence of mixed biofilms in automobile air conditioning systems.

    PubMed

    Simmons, R B; Rose, L J; Crow, S A; Ahearn, D G

    1999-09-01

    Twelve automobile air conditioner systems from six manufacturers and three countries, selected mostly because of complaints of unpleasant odors in the passenger compartment, were examined for microbial growth by direct microscopy and enrichment culture. Mixed populations of fungi and bacteria (with occasional protozoa) were observed in biofilms in at least some of the components from all used units. The aluminum heat exchanger fins from ten evaporators demonstrated bacterial biofilms that yielded Methylobacterium mesophilicum. Penicillium viridicatum colonized components from four units. These bacteria and fungi were recoverable repeatedly from these units during 'dry' storage of up to 27 months. This report associates a bacterial-fungal community with disagreeable air quality in some automobiles. PMID:10441727

  14. Brominated, chlorinated and mixed brominated/chlorinated persistent organic pollutants in European eels (Anquilla anquilla) from Latvian lakes.

    PubMed

    Zacs, Dzintars; Rjabova, Jekaterina; Fernandes, Alwyn; Bartkevics, Vadims

    2016-03-01

    Fifty-eight European eel (Anquilla anquilla) specimens collected from five Latvian lakes were investigated for six groups of persistent organic pollutants (POPs), including polychlorinated, polybrominated and mixed bromo-chloro dibenzo-p-dioxins and dibenzofurans (PCDD/DFs, PBDD/DFs and PXDD/DFs), polychlorinated and mixed bromo-chloro biphenyls (PCBs and PXBs) and polybrominated diphenyl ethers (PBDEs). PCDD/DFs and PCBs were found to occur in the range 0.85-15.8 pg Total-WHO2005-TEQ g(-1) f.w., and concentrations in most of the samples were below the maximum levels specified in European Commission Regulation (EU) No. 1259/2011. The summed concentrations of 27 PBDEs (∑PBDE) and 16 non-dioxin-like PCBs (∑NDL-PCB) were in the ranges of 0.28-26.7 and 6.37-320 ng g(-1) f.w., respectively. PBDD/DFs, PXDD/DFs and PXBs show average upper-bound concentrations of 0.05, 0.06 and 0.01 pg TEQ f.w. and collectively contributed 3.4% to the sum TEQ of dioxin-like compounds. The highest contaminant concentrations were measured in samples from lakes near the Baltic Sea and the industrialised area near Riga (Liepajas and Kisezers lakes). A correlation of POP concentration with the length of collected specimens was observed. PMID:26730547

  15. Hepatitis C eradication and improvement of cryoglobulinemia-associated rash and membranoproliferative glomerulonephritis with interferon and ribavirin after kidney transplantation

    PubMed Central

    Zeman, Marilyn; Campbell, Patricia; Bain, Vincent G

    2006-01-01

    Postrenal transplant hepatitis C is increasing in frequency due to the high prevalence of hepatitis C among patients with renal failure. Despite this, there is still no standard hepatitis C treatment available for renal transplanted recipients. Combination antiviral hepatitis C therapy, the standard of care in the nontransplant population, is generally avoided because of documented renal graft rejection secondary to interferon treatment. A case of a male patient with postrenal transplant hepatitis C, which was associated with cryoglobulinemia and glomerulonephritis of the graft, is presented. He was treated with standard interferon with ribavirin. Sustained viral clearance was achieved despite ongoing evidence of cryoglobulinemia. Renal function, which had been deteriorating before treatment, improved as evidenced by the stabilization of serum creatinine and marked improvement of proteinuria. In conclusion, in selected patients, combination antiviral therapy may still be a viable option postrenal transplant. PMID:16779461

  16. Large-eddy simulation of three mixed-phase cloud events during ISDAC: Conditions for persistent heterogeneous ice formation

    NASA Astrophysics Data System (ADS)

    Savre, J.; Ekman, A. M. L.

    2015-08-01

    A Classical-Nucleation-Theory-based parameterization for heterogenous ice nucleation, including explicit dependencies of the nucleation rates on the number concentration, size, and composition of the ambient aerosol population, is implemented in a cloud-scale, large-eddy simulation model and evaluated against Arctic mixed-phase cloud events observed during Indirect and Semi-Direct Aerosol Campaign (ISDAC). An important feature of the parameterization is that the ice nucleation efficiency of each considered aerosol type is described using a contact angle distribution which evolves with time so that the model accounts for the inhibition of ice nucleation as the most efficient ice-forming particles are nucleated and scavenged. The model gives a reasonable representation of first-order (ice water paths) and second-order (ice crystal size distributions) ice microphysical properties. The production of new ice crystals in the upper part of the cloud, essential to guarantee sustained mixed-phase conditions, is found to be controlled mostly by the competition between radiative cooling (resulting in more aerosol particles becoming efficient ice nuclei as the temperature decreases), cloud-top entrainment (entraining fresh particles into the cloud), and nucleation scavenging of the ice+forming aerosol particles. The relative contribution of each process is mostly determined by the cloud-top temperature and the entrainment rates. Accounting for the evolution of the contact angle probability density function with time seems to be essential to capture the persistence of in-cloud ice production without having to, for example, increase the free tropospheric aerosol concentration. Although limited to only three cases and despite important limitations of the parameterization (e.g., the present version only considers dust and black carbon as potential ice nuclei), the results suggest that modeling the time evolution of the ice nuclei population ability to form ice is required to

  17. Complexities in Isolation and Purification of Multiple Viruses from Mixed Viral Infections: Viral Interference, Persistence and Exclusion

    PubMed Central

    Kumar, Naveen; Barua, Sanjay; Riyesh, Thachamvally; Chaubey, Kundan K.; Rawat, Krishan Dutt; Khandelwal, Nitin; Mishra, Anil K.; Sharma, Nitika; Chandel, Surender S.; Sharma, Shalini; Singh, Manoj K.; Sharma, Dinesh K.; Singh, Shoor V.; Tripathi, Bhupendra N.

    2016-01-01

    Successful purification of multiple viruses from mixed infections remains a challenge. In this study, we investigated peste des petits ruminants virus (PPRV) and foot-and-mouth disease virus (FMDV) mixed infection in goats. Rather than in a single cell type, cytopathic effect (CPE) of the virus was observed in cocultured Vero/BHK-21 cells at 6th blind passage (BP). PPRV, but not FMDV could be purified from the virus mixture by plaque assay. Viral RNA (mixture) transfection in BHK-21 cells produced FMDV but not PPRV virions, a strategy which we have successfully employed for the first time to eliminate the negative-stranded RNA virus from the virus mixture. FMDV phenotypes, such as replication competent but noncytolytic, cytolytic but defective in plaque formation and, cytolytic but defective in both plaque formation and standard FMDV genome were observed respectively, at passage level BP8, BP15 and BP19 and hence complicated virus isolation in the cell culture system. Mixed infection was not found to induce any significant antigenic and genetic diversity in both PPRV and FMDV. Further, we for the first time demonstrated the viral interference between PPRV and FMDV. Prior transfection of PPRV RNA, but not Newcastle disease virus (NDV) and rotavirus RNA resulted in reduced FMDV replication in BHK-21 cells suggesting that the PPRV RNA-induced interference was specifically directed against FMDV. On long-term coinfection of some acute pathogenic viruses (all possible combinations of PPRV, FMDV, NDV and buffalopox virus) in Vero cells, in most cases, one of the coinfecting viruses was excluded at passage level 5 suggesting that the long-term coinfection may modify viral persistence. To the best of our knowledge, this is the first documented evidence describing a natural mixed infection of FMDV and PPRV. The study not only provides simple and reliable methodologies for isolation and purification of two epidemiologically and economically important groups of viruses, but

  18. Complexities in Isolation and Purification of Multiple Viruses from Mixed Viral Infections: Viral Interference, Persistence and Exclusion.

    PubMed

    Kumar, Naveen; Barua, Sanjay; Riyesh, Thachamvally; Chaubey, Kundan K; Rawat, Krishan Dutt; Khandelwal, Nitin; Mishra, Anil K; Sharma, Nitika; Chandel, Surender S; Sharma, Shalini; Singh, Manoj K; Sharma, Dinesh K; Singh, Shoor V; Tripathi, Bhupendra N

    2016-01-01

    Successful purification of multiple viruses from mixed infections remains a challenge. In this study, we investigated peste des petits ruminants virus (PPRV) and foot-and-mouth disease virus (FMDV) mixed infection in goats. Rather than in a single cell type, cytopathic effect (CPE) of the virus was observed in cocultured Vero/BHK-21 cells at 6th blind passage (BP). PPRV, but not FMDV could be purified from the virus mixture by plaque assay. Viral RNA (mixture) transfection in BHK-21 cells produced FMDV but not PPRV virions, a strategy which we have successfully employed for the first time to eliminate the negative-stranded RNA virus from the virus mixture. FMDV phenotypes, such as replication competent but noncytolytic, cytolytic but defective in plaque formation and, cytolytic but defective in both plaque formation and standard FMDV genome were observed respectively, at passage level BP8, BP15 and BP19 and hence complicated virus isolation in the cell culture system. Mixed infection was not found to induce any significant antigenic and genetic diversity in both PPRV and FMDV. Further, we for the first time demonstrated the viral interference between PPRV and FMDV. Prior transfection of PPRV RNA, but not Newcastle disease virus (NDV) and rotavirus RNA resulted in reduced FMDV replication in BHK-21 cells suggesting that the PPRV RNA-induced interference was specifically directed against FMDV. On long-term coinfection of some acute pathogenic viruses (all possible combinations of PPRV, FMDV, NDV and buffalopox virus) in Vero cells, in most cases, one of the coinfecting viruses was excluded at passage level 5 suggesting that the long-term coinfection may modify viral persistence. To the best of our knowledge, this is the first documented evidence describing a natural mixed infection of FMDV and PPRV. The study not only provides simple and reliable methodologies for isolation and purification of two epidemiologically and economically important groups of viruses, but

  19. Persistence of insecticides in ready-mix formulations and their efficacy against Lipaphis erysimi (Kalt) in cauliflower.

    PubMed

    Gupta, Suman; Sharma, R K; Gajbhiye, V T; Gupta, R K

    2013-03-01

    Persistence of cypermethrin, deltamethrin, profenofos, and triazophos in cauliflower curd was studied, following application of two premix formulations viz: Roket 44EC (profenofos 40 % + cypermethrin 4 %) and Anaconda Plus 36EC (triazophos 35 % + deltamethrin 1 %) at recommended (1.0 L ha(-1)) and double doses (2.0 L ha(-1)). In the case of Roket 44EC, residues of cypermethrin dissipated with the half-life values of 1.5-2.1 days, whereas residues of profenofos dissipated with the half-life of 2.9-3.3 days on cauliflower curd. In the case of Anaconda, residues of triazophos and deltamethrin dissipated from curd with the half-life values of 2.6-3.0 and 2.2-2.6 days, respectively. Both the combination mix significantly reduced the aphid population up to 14 days after spray and increased the yield by 155-160 % over control. Anaconda (2.0 L ha(-1)) treated plots yielded the highest number of marketable curds. Based on risk assessment analysis, safe waiting period of 3 and 5 days has been suggested for Roket 44EC and Anaconda Plus 36EC, respectively, in cauliflower at recommended dose of application. PMID:22648021

  20. Delineation of autoantibody repertoire through differential proteogenomics in hepatitis C virus-induced cryoglobulinemia.

    PubMed

    Ogishi, Masato; Yotsuyanagi, Hiroshi; Moriya, Kyoji; Koike, Kazuhiko

    2016-01-01

    Antibodies cross-reactive to pathogens and autoantigens are considered pivotal in both infection control and accompanying autoimmunity. However, the pathogenic roles of autoantibodies largely remain elusive without a priori knowledge of disease-specific autoantigens. Here, through a novel quantitative proteogenomics approach, we demonstrated a successful identification of immunoglobulin variable heavy chain (VH) sequences highly enriched in pathological immune complex from clinical specimens obtained from a patient with hepatitis C virus-induced cryoglobulinemia (HCV-CG). Reconstructed single-domain antibodies were reactive to both HCV antigens and potentially liver-derived human proteins. Moreover, over the course of antiviral therapy, a substantial "de-evolution" of a distinct sub-repertoire was discovered, to which proteomically identified cryoprecipitation-prone autoantibodies belonged. This sub-repertoire was characterized by IGHJ6*03-derived, long, hydrophobic complementarity determining region (CDR-H3). This study provides a proof-of-concept of de novo mining of autoantibodies and corresponding autoantigen candidates in a disease-specific context in human, thus facilitating future reverse-translational research for the discovery of novel biomarkers and the development of antigen-specific immunotherapy against various autoantibody-related disorders. PMID:27403724

  1. Aberrant immunoglobulin and c-myc gene rearrangements in patients with nonmalignant monoclonal cryoglobulinemia

    SciTech Connect

    Perl, A.; Wang, N.; Williams, J.M.; Hunt, M.J.; Rosenfeld, S.I.; Condemi, J.J.; Packman, C.H.; Abraham, G.N.

    1987-11-15

    The status of the immunoglobulin (Ig) genes was investigated in patients with idiopathic nonmalignant monoclonal IgG cryoglobulinemia (NCG). In NCG, monoclonal antibodies are synthesized at an accelerated rate by nonmalignant B lymphocytes. In order to determine whether this high production rate is related to a clonal B cell expansion, the rearrangement of the Ig genes was investigated by Southern blot analysis of genomic, /sup 32/P-labelled, DNA extracted from the peripheral blood lymphocytes of four NCG patients. In three of four (VI, BR, and CH) clonal expansion of B cells was detected using probes specific for the genes. BamHI digestion of DNA from VI and BR produced three rearranged fragments which cohybridized with two of the probes. This finding suggested the presence of additional nonsecretory B cell clones and/or disruption of the gene segments spanned by and detected with the probes. In addition, the possibility of aberrant gene rearrangements was supported by noting the alteration of the c-myc gene locus in genomic DNA from peripheral blood leukocytes of VI and CH. Northern blot analysis of RNA isolated from peripheral blood B cells of VI and CH demonstrated aberrant transcripts of the c-myc gene, showing an active role of the altered c-myc locus. Detection of c-myc rearrangement in NCG patients clearly shows that this event may not be a final step in malignant B cell transformation.

  2. Delineation of autoantibody repertoire through differential proteogenomics in hepatitis C virus-induced cryoglobulinemia

    PubMed Central

    Ogishi, Masato; Yotsuyanagi, Hiroshi; Moriya, Kyoji; Koike, Kazuhiko

    2016-01-01

    Antibodies cross-reactive to pathogens and autoantigens are considered pivotal in both infection control and accompanying autoimmunity. However, the pathogenic roles of autoantibodies largely remain elusive without a priori knowledge of disease-specific autoantigens. Here, through a novel quantitative proteogenomics approach, we demonstrated a successful identification of immunoglobulin variable heavy chain (VH) sequences highly enriched in pathological immune complex from clinical specimens obtained from a patient with hepatitis C virus-induced cryoglobulinemia (HCV-CG). Reconstructed single-domain antibodies were reactive to both HCV antigens and potentially liver-derived human proteins. Moreover, over the course of antiviral therapy, a substantial “de-evolution” of a distinct sub-repertoire was discovered, to which proteomically identified cryoprecipitation-prone autoantibodies belonged. This sub-repertoire was characterized by IGHJ6*03-derived, long, hydrophobic complementarity determining region (CDR-H3). This study provides a proof-of-concept of de novo mining of autoantibodies and corresponding autoantigen candidates in a disease-specific context in human, thus facilitating future reverse-translational research for the discovery of novel biomarkers and the development of antigen-specific immunotherapy against various autoantibody-related disorders. PMID:27403724

  3. Policy and Persistence: An Exploratory Mixed Methods Case Study of "Last Mile" Students at Portland State University

    ERIC Educational Resources Information Center

    Wubbold, Joseph Mark

    2012-01-01

    In an extension of educational attainment research, this exploratory mixed- methods case study examines the influence of institutional policies on the behavior of five cohorts (n = 925) of traditional first time, full time (FTFT) freshmen--called "Last Mile" students--at one urban research university located in the Pacific Northwest.…

  4. Persistent photoconductivity and optically stimulated luminescence in Zn0.8Mg0.2Se mixed crystals

    NASA Astrophysics Data System (ADS)

    Firszt, F.; McZyska, H.; Gowski, S.; Zakrzewski, J.; Strzakowski, K.; Wróbel, M.

    2004-03-01

    Photoelectric properties of Zn0.8Mg0.2Se mixed crystals grown by high pressure Bridgman method were investigated. Spectral distributions and temperature characteristics of photoconductivity as well as thermal and optical stimulation and quenching of luminescence and photoconductivity were measured. Relaxation of stored carriers were discussed in terms of random local potential fluctuation (RLPF) due to statistical fluctuations of composition. Based on the observed photoinduced phenomena in ZnxMg1-xSe, the potential applications of II-VI solid solutions for construction of optoelectronic devices were discussed.

  5. Long-term mass transfer and mixing-controlled reactions of a DNAPL plume from persistent residuals

    NASA Astrophysics Data System (ADS)

    Liu, Yuan; Illangasekare, Tissa H.; Kitanidis, Peter K.

    2014-02-01

    Understanding and being able to predict the long-term behavior of DNAPL (i.e., PCE and TCE) residuals after active remediation has ceased have become increasingly important as attention at many sites turns from aggressive remediation to monitored natural attenuation and long-term stewardship. However, plume behavior due to mass loading and reactions during these later phases is less studied as they involve large spatial and temporal scales. We apply both theoretical analysis and pore-scale simulations to investigate mass transfer from DNAPL residuals and subsequent reactions within the generated plume, and, in particular, to show the differences between early- and late-time behaviors of the plume. In the zone of entry of the DNAPL entrapment zone where the concentration boundary layer in the flowing groundwater has not fully developed, the pore-scale simulations confirm the past findings based on laboratory studies that the mass transfer increases as a power-law function of the Peclét number, and is enhanced due to reactions in the plume. Away from the entry zone and further down gradient, the long-term reactions are limited by the available additive and mixing in the porous medium, thereby behave considerably differently from the entry zone. For the reaction between the contaminant and an additive with intrinsic second-order bimolecular kinetics, the late-time reaction demonstrates a first-order decay macroscopically with respect to the mass of the limiting additive, not with respect to that of the contaminant. The late-time decay rate only depends on the intrinsic reaction rate and the solubility of the entrapped DNAPL. At the intermediate time, the additive decays exponentially with the square of time (t2), instead of time (t). Moreover, the intermediate decay rate also depends on the initial conditions, the spatial distribution of DNAPL residuals, and the effective dispersion coefficient.

  6. Non HCV-related infectious cryoglobulinemia vasculitis: Results from the French nationwide CryoVas survey and systematic review of the literature.

    PubMed

    Terrier, Benjamin; Marie, Isabelle; Lacraz, Adeline; Belenotti, Pauline; Bonnet, Fabrice; Chiche, Laurent; Graffin, Bruno; Hot, Arnaud; Kahn, Jean-Emmanuel; Michel, Catherine; Quemeneur, Thomas; de Saint-Martin, Luc; Hermine, Olivier; Léger, Jean-Marc; Mariette, Xavier; Senet, Patricia; Plaisier, Emmanuelle; Cacoub, Patrice

    2015-12-01

    In patients with infectious cryoglobulinemia vasculitis (CryoVas) in the absence of hepatitis C virus infection, data on presentation, therapeutic management and outcome are lacking. We conducted a nationwide survey that included patients with HCV-negative CryoVas. We describe here the presentation, therapeutic management and outcome of 18 patients with non-HCV infectious CryoVas and 27 additional patients identified form a systematic review of the literature. We included 18 patients, mean age 57.9±13.5 years. Infectious causes were viral infections in 8 patients [hepatitis B virus (HBV) in 4, and cytomegalovirus, Epstein Barr virus, parvovirus B19 and human immunodeficiency virus in one case each], pyogenic bacterial infection in 6 patients, parasitic infection in 2 patients, and leprosy and candidiasis in one case each. Baseline manifestations were purpura (78%), glomerulonephritis (28%), arthralgia (28%), peripheral neuropathy (22%), skin necrosis (22%), cutaneous ulcers (17%), and myalgia (11%). Cryoglobulinemia was type II in 2/3 of cases. Most cases received specific anti-infectious therapy as first-line therapy, sometimes associated with corticosteroids, achieving sustained remission in the majority of cases. Refractory or relapsing patients, frequently related to HBV infection, showed a complete remission after rituximab in addition to antiviral therapy. In contrast, corticosteroids and/or immunosuppressive agents used in the absence of anti-infectious agents were frequently associated with refractory CryoVas. Viral and pyogenic bacterial infections represent the main causes of non-HCV infectious CryoVas. Antimicrobial therapy is commonly associated with sustained remission. Immunosuppressive agents should be considered only as a second-line option in patients with refractory vasculitis. PMID:26320984

  7. Portraits of Success: A Mixed-Method Study of the Enrollment, Persistence, and Success Experiences of Female Graduate Engineering Students at a Hispanic Serving Institution

    ERIC Educational Resources Information Center

    Aguirre-Covarrubias, Sandra

    2013-01-01

    The current study addresses the underrepresentation of female graduate engineering students. Specifically, its purpose was to gain insight on how enrollment, persistence, and success factors are experienced by female graduate engineering students at a Hispanic Serving Institution located on the U.S.-Mexico border. The topic of underrepresentation…

  8. Quantitatively different red cell/nucleated cell chimerism in patients with long-term, persistent hematopoietic mixed chimerism after bone marrow transplantation for thalassemia major or sickle cell disease

    PubMed Central

    Andreani, Marco; Testi, Manuela; Gaziev, Javid; Condello, Rossella; Bontadini, Andrea; Tazzari, Pier Luigi; Ricci, Francesca; De Felice, Lidia; Agostini, Francesca; Fraboni, Daniela; Ferrari, Giuliana; Battarra, Mariarosa; Troiano, Maria; Sodani, Pietro; Lucarelli, Guido

    2011-01-01

    Background Persistent mixed chimerism represents a state in which recipient and donor cells stably co-exist after hematopoietic stem cell transplantation. However, since in most of the studies reported in literature the engraftment state was observed in the nucleated cells, in this study we determined the donor origin of the mature erythrocytes of patients with persistent mixed chimerism after transplantation for hemoglobinopathies. Results were compared with the engraftment state observed in singly picked out burst-forming unit – erythroid colonies and in the nucleated cells collected from the peripheral blood and from the bone marrow. Design and Methods The donor origin of the erythrocytes was determined analyzing differences on the surface antigens of the erythrocyte suspension after incubation with anti-ABO and/or anti-C, -c, -D, -E and -e monoclonal antibodies by a flow cytometer. Analysis of short tandem repeats was used to determine the donor origin of nucleated cells and burst-forming unit – erythroid colonies singly picked out after 14 days of incubation. Results The proportions of donor-derived nucleated cells in four transplanted patients affected by hemoglobinopathies were 71%, 46%, 15% and 25% at day 1364, 1385, 1314 and 932, respectively. Similar results were obtained for the erythroid precursors, analyzing the donor/recipient origin of the burst-forming unit – erythroid colonies. In contrast, on the same days of observation, the proportions of donor-derived erythrocytes in the four patients with persistent mixed chimerism were 100%, 100%, 73% and 90%. Conclusions Our results showed that most of the erythrocytes present in four long-term transplanted patients affected by hemoglobinopathies and characterized by the presence of few donor engrafted nucleated cells were of donor origin. The indication that small proportions of donor engrafted cells might be sufficient for clinical control of the disease in patients affected by hemoglobinopathies is

  9. [Persistent diarrhea

    PubMed

    Andrade, J A; Moreira, C; Fagundes Neto, U

    2000-07-01

    INTRODUCTION: Persistent diarrhea has high impact on infantile morbidity and mortality rates in developing countries. Several studies have shown that 3 to 20% of acute diarrheal episodes in children under 5 years of age become persistent. DEFINITION: Persistent diarrhea is defined as an episode that lasts more than 14 days. ETIOLOGY: The most important agents isolated in persistent diarrhea are: Enteropathogenic E. coli (EPEC), Salmonella, Enteroaggregative E. coli (EAEC), Klebisiella and Cryptosporidium. CLINICAL ASPECTS: In general, the clinical characteristics of patients with persistent diarrhea do not change with the pathogenic agent. Persistent diarrhea seems to represent the final result of a several insults a infant suffers that predisposes to a more severe episode of diarrhea due to a combination of host factors and high rates of enviromental contamination. Therefore, efforts should be made to promptly treat all episodes of diarrhea with apropriate follow-up. THERAPY: The aim of the treatment is to restore hydroelectrolytic deficits and to replace losses until the diarrheal ceases. It is possible in the majority of the cases, using oral rehydration therapy and erly an appropriate type of diet. PREVENTION: It is imperative that management strategies also focus on preventive aspects. The most effective diarrheal prevention strategy in young infants worldwide is promotion of exclusive breast feeding. PMID:14676915

  10. Persistence in ozone scaling under the Hurst exponent as an indicator of the relative rates of chemistry and fluid mechanical mixing in the stratosphere

    SciTech Connect

    Tuck, A.F.; Hovde, S.J.; Proffitt, M.H.

    1999-12-09

    The observed self-affine fractal behavior of ozone, wind, and temperature in the stratosphere is used to produce an indication of the rate of occurrence of chemistry relative to that of fluid mixing which, unlike the usual method, is independent of an assumed mechanism sequence of elementary chemical steps followed by application of the law of mass action to obtain differential equations describing the temporal and spatial evolution of the reacting gases. Rather, the occurrence of chemistry is deduced from the scaling of the observed variability; it is applied empirically to deduce the presence of chemical processes that are faster than fluid mechanical mixing above an altitude of 19 km during a balloon flight, and in the Antarctic spring, Arctic summer, and Arctic winter during high altitude aircraft flights. The method should apply to any volume of reacting molecules to which the equations of fluid motion apply and for which measurements can be made over a range of scales.

  11. Semibiotic Persistence

    NASA Astrophysics Data System (ADS)

    Prothmann, C.; Zauner, K.-P.

    From observation, we find four different strategies to successfully enable structures to persist over extended periods of time. If functionally relevant features are very large compared to the changes that can be effectuated by entropy, the functional structure itself has a high enough probability to erode only slowly over time. If the functionally relevant features are protected from environmental influence by sacrificial layers that absorb the impinging of the environment, deterioration can be avoided or slowed. Loss of functionality can be delayed, even for complex systems, by keeping alternate options for all required components available. Biological systems also apply information processing to actively counter the impact of entropy by mechanisms such as self-repair. The latter strategy increases the overall persistence of living systems and enables them to maintain a highly complex functional organisation during their lifetime and over generations. In contrast to the other strategies, information processing has only low material overhead. While at present engineered technology is far from achieving the self-repair of evolved systems, the semibiotic combination of biological components with conventionally engineered systems may open a path to long-term persistence of functional devices in harsh environments. We review nature's strategies for persistence, and consider early steps taken in the laboratory to import such capabilities into engineered architectures.

  12. Patient outcomes and experiences of an acupuncture and self-care service for persistent low back pain in the NHS: a mixed methods approach

    PubMed Central

    2013-01-01

    Background Supported self-management, acupuncture and information can help reduce the symptoms of low back pain. These approaches are currently recommended by NICE guidance as treatment options for patients with persistent low back pain. However, there has been no previous evaluation of a service providing them together for this common problem. The purpose of this service evaluation was to report patient outcomes and experiences of the Beating Back Pain Service (BBPS), a pilot service based in a primary and community care setting, delivering acupuncture, self-management and information to patients with chronic low back pain. Methods Patients completed a questionnaire at three time points: pre-BBPS, immediately post-BBPS and three months post-BBPS. Outcome measures included the Bournemouth Questionnaire (measuring musculoskeletal, MSK, problems), EuroQoL-5D (measuring quality of life), Pain and Self-efficacy Questionnaire, and additional questions on medication use, physical activity, understanding of pain and positive well-being. Additionally, the STarT Back (measuring risk of developing chronic pain) was collected at BBPS information sessions. Non-parametric tests were used to evaluate pre- and post- variables. Questionnaires also collected qualitative data (open-text responses) regarding patient views and experiences of the BBPS, which were analysed using thematic analysis. Results 80 (out of 108) patients who attended the initial BBPS information session agreed to participate in the service evaluation (mean age 47 years, 65% female). 65 patients attended subsequent BBPS acupuncture and/or self-management sessions and were asked to complete post-treatment questionnaires; complete datasets were available for 61 patients. There were statistically significant improvements over time for pain (p <0.0001), quality of life (p = 0.006), understanding of pain (p <0.001), physical activity (p = 0.047) and relaxation (p = 0.012). Post-hoc analysis revealed that

  13. Response: persistent perplexities.

    PubMed

    Radin, M J

    2001-09-01

    This response to the preceding five articles highlights the stubborn persistence of the philosophical perplexities surrounding commodification in the realm of medicine and biotechnology. PMID:11700685

  14. Community College Students' Self-Reports of Persistence: Looking beyond Student Satisfaction Ratings of Persisters and Nonpersisters

    ERIC Educational Resources Information Center

    Cole, Marsha Dee

    2013-01-01

    Approximately 30% of students who persist to the end of their courses at two-year colleges do not do so with a passing grade, yet research on the educational experiences of these unsuccessful community college persisters remains limited. The purpose of this explanatory mixed-methods study was threefold. First, this study attempted to identify…

  15. Persistent depressive disorder

    MedlinePlus

    The exact cause of persistent depressive disorder (PDD) is unknown. It tends to run in families. PDD occurs more often in women. Most people with PDD will also have an episode of major depression at some point in their lives. ...

  16. Persistent heap Management library

    Energy Science and Technology Software Center (ESTSC)

    2012-01-17

    PERM is a C library for persistent heap management and is intended for use with a dynamic-memory allocator (e.g. malloc, free). The PERM memory allocator replaces the standard C dynamic memory allocation functions with compatible versions that provide persistent memory to application programs. Memory allocated with the PERM allocatory will persist between program invocations after a call to a checkpoint function. This function essentially saves the state of the heap and registered global variables tomore » a file which may reside in flash memory or other node local storage. A few other functions are also provided by the library to manage checkpoint files. Global variables in an application can be marked persistent and be included in a checkpoint by using a compiler attribute defined as PERM. The PERM checkpoint methof is not dependent on the programming model ans works with distributed memory or shared memory programs.« less

  17. Persistent heap Management library

    SciTech Connect

    2012-01-17

    PERM is a C library for persistent heap management and is intended for use with a dynamic-memory allocator (e.g. malloc, free). The PERM memory allocator replaces the standard C dynamic memory allocation functions with compatible versions that provide persistent memory to application programs. Memory allocated with the PERM allocatory will persist between program invocations after a call to a checkpoint function. This function essentially saves the state of the heap and registered global variables to a file which may reside in flash memory or other node local storage. A few other functions are also provided by the library to manage checkpoint files. Global variables in an application can be marked persistent and be included in a checkpoint by using a compiler attribute defined as PERM. The PERM checkpoint methof is not dependent on the programming model ans works with distributed memory or shared memory programs.

  18. Persistent depressive disorder

    MedlinePlus

    PDD; Chronic depression; Depression - chronic ... The exact cause of persistent depressive disorder (PDD) is unknown. It tends to run in families. PDD occurs more often in women. Most people with PDD will also ...

  19. The Sunk Cost Effect with Pigeons: Some Determinants of Decisions about Persistence

    ERIC Educational Resources Information Center

    Macaskill, Anne C.; Hackenberg, Timothy D.

    2012-01-01

    The sunk cost effect occurs when an individual persists following an initial investment, even when persisting is costly in the long run. The current study used a laboratory model of the sunk cost effect. Two response alternatives were available: Pigeons could persist by responding on a schedule key with mixed ratio requirements, or escape by…

  20. Persistence and financial markets

    NASA Astrophysics Data System (ADS)

    Jain, S.

    2007-09-01

    The persistence phenomenon is studied in a financial context by using a novel mapping of the time evolution of the values of shares in a portfolio onto Ising spins. The method is applied to historical data from the London Financial Times Stock Exchange 100 index (FTSE 100) over an arbitrarily chosen period. By following the time dependence of the spins, we find evidence for a power law decay of the proportion of shares that remain either above or below their ‘starting’ values. As a result, we estimate a persistence exponent for the underlying financial market to be ≈0.5. Preliminary results from computer simulations on persistence in the economic dynamics of a toy model appear to reproduce the behaviour observed in real markets.

  1. Why Do Delusions Persist?

    PubMed Central

    Corlett, Philip R.; Krystal, John H.; Taylor, Jane R.; Fletcher, Paul C.

    2009-01-01

    Delusions are bizarre and distressing beliefs that characterize certain mental illnesses. They arise without clear reasons and are remarkably persistent. Recent models of delusions, drawing on a neuroscientific understanding of learning, focus on how delusions might emerge from abnormal experience. We believe that these models can be extended to help us understand why delusions persist. We consider prediction error, the mismatch between expectancy and experience, to be central. Surprising events demand a change in our expectancies. This involves making what we have learned labile, updating and binding the memory anew: a process of memory reconsolidation. We argue that, under the influence of excessive prediction error, delusional beliefs are repeatedly reconsolidated, strengthening them so that they persist, apparently impervious to contradiction. PMID:19636384

  2. The Persistence of PCBs.

    ERIC Educational Resources Information Center

    Boyle, Robert H.; Highland, Joseph H.

    1979-01-01

    PCB's are one of the most persistent chemicals ever introduced into the environment by man. From very early in their history of manufacture PCB's were suspected of being hazardous to health, but public awareness of the hazard was slow in coming. (RE)

  3. A Very Persistent Mistake

    ERIC Educational Resources Information Center

    McClelland, J. A. G.

    2011-01-01

    Articulated bodies with an internal energy source require to be coupled to an external mass in order to accelerate themselves but the typical text book assertion that the net force is provided by the external mass is not correct. Arguments are presented demonstrating that the assertion is incorrect and reasons are suggested for the persistence of…

  4. Retention and Persistence Data.

    ERIC Educational Resources Information Center

    Sanford, Timothy R.

    Two studies are combined with an introductory section: one is "Persistence to Graduation for Freshmen Entering the University of North Carolina at Chapel Hill, 1967-75," by Timothy Sanford, and the second is "Freshman, Transfer, Professional, Masters, and Doctoral Student Retention at the University of North Carolina at Chapel Hill," by Paul D.…

  5. Persistent fetal circulation.

    PubMed

    Saucier, P H

    1980-01-01

    A review of persistent fetal circulation, which involves the presence of a right to left extrapulmonary shunt that is sustained into neonatal life, is presented. Clinical signs exhibited by the infant often resemble those of respiratory distress. Treatment is accomplished with hyperventilation and/or pharmacologically with tolazoline which, in addition to the usual attention to the overall condition of the infant, requires intensive monitoring by the nurse. PMID:6898712

  6. Persistent interface fluid syndrome.

    PubMed

    Hoffman, Richard S; Fine, I Howard; Packer, Mark

    2008-08-01

    We present an unusual case of persistent interface fluid that would not resolve despite normal intraocular pressure and corneal endothelial replacement with Descemet-stripping endothelial keratoplasty. Dissection, elevation, and repositioning of the laser in situ keratomileusis flap were required to resolve the interface fluid. Circumferential corneal graft-host margin scar formation acting as a mechanical strut may have been the cause of the intractable interface fluid. PMID:18655997

  7. Persistent fetal circulation

    PubMed Central

    D’cunha, Chrysal; Sankaran, Koravangattu

    2001-01-01

    Persistent fetal circulation (PFC), also known as persistent pulmonary hypertension of the newborn, is defined as postnatal persistence of right-to-left ductal or atrial shunting, or both in the presence of elevated right ventricular pressure. It is a relatively rare condition that is usually seen in newborns with respiratory distress syndrome, overwhelming sepsis, meconium and other aspiration syndromes, intrauterine hypoxia and ischemia, and/or neonatal hypoxia and ischemia. This condition causes severe hypoxemia, and, as a result, has significant morbidity and mortality. Improved antenatal and neonatal care; the use of surfactant; continuous monitoring of oxygenation, blood pressure and other vital functions; and early recognition and intervention have made this condition even more rare. In modern neonatal intensive care units, anticipation and early treatment of PFC and its complications in sick newborns are commonplace. Thus, severe forms of PFC are only seen on isolated occasions. Consequently, it is even more imperative to revisit PFC compared with the time when there were occasional cases of PFC seen in neonatal intensive care units, and to discuss evolving treatment and management issues that pertain to this syndrome. PMID:20084150

  8. Learning's "Weak" Link to Persistence

    ERIC Educational Resources Information Center

    Wolniak, Gregory C.; Mayhew, Matthew J.; Engberg, Mark E.

    2012-01-01

    This study advances the understanding of college persistence by examining five dimensions of student learning in relation to second-year persistence. Two of the five dimensions of learning were found to be significant predictors of persistence, and each was moderated by social integration. (Contains 5 tables and 1 figure.)

  9. Systems for persistent surveillance

    NASA Astrophysics Data System (ADS)

    Lewis, Keith

    2011-09-01

    The requirements for a persistent wide-area surveillance system are discussed in the context of evolving military operations. Significant emphasis has been placed on the development of new sensing technologies to meet the challenges posed by asymmetric threats. Within the UK, the Electro-Magnetic Remote Sensing Defence Technology Centre (EMRS DTC) has supported the research and development of new capabilities including radio-frequency (RF) and electro-optic (EO) systems, as well as work on sensor exploitation, with a goal of developing solutions for enhancing situational awareness. This activity has been supported by field trials to determine the efficacy of competing technologies in relation to realistic threat scenarios.

  10. Persistence of Salmonid Redds

    NASA Astrophysics Data System (ADS)

    Buffington, J. M.; Buxton, T.; Fremier, A. K.; Hassan, M. A.; Yager, E.

    2013-12-01

    The construction of redds by spawning salmonids modifies fluvial processes in ways that are beneficial to egg and embryo survival. Redd topography induces hyporheic flow that oxygenates embryos incubating within the streambed and creates form drag that reduces bed mobility and scour of salmonid eggs. Winnowing of fine material during redd construction also coarsens the streambed, increasing bed porosity and hyporheic flow and reducing bed mobility. In addition to the biological benefits, redds may influence channel morphology by altering channel hydraulics and bed load transport rates depending on the size and extent of redds relative to the size of the channel. A key question is how long do the physical and biological effects of redds last? Field observations indicate that in some basins redds are ephemeral, with redd topography rapidly erased by subsequent floods, while in other basins, redds can persist for years. We hypothesize that redd persistence is a function of basin hydrology, sediment supply, and characteristics of the spawning fish. Hydrology controls the frequency and magnitude of bed mobilizing flows following spawning, while bed load supply (volume and caliber) controls the degree of textural fining and consequent bed mobility after spawning, as well as the potential for burial of redd features. The effectiveness of flows in terms of their magnitude and duration depend on hydroclimate (i.e., snowmelt, rainfall, or transitional hydrographs), while bed load supply depends on basin geology, land use, and natural disturbance regimes (e.g., wildfire). Location within the stream network may also influence redd persistence. In particular, lakes effectively trap sediment and regulate downstream flow, which may promote long-lived redds in stream reaches below lakes. These geomorphic controls are modulated by biological factors: fish species (size of fish controls size of redds and magnitude of streambed coarsening); life history (timing of spawning and

  11. Special Education Teacher Persistence

    ERIC Educational Resources Information Center

    Thorp, Sally A.

    2013-01-01

    The focus of this study was special education teachers, who remained in the teaching field 5 or more years. Through the use of qualitative mixed-methods study, variables contributing to their longevity were explored. Research indicates that 50% of special education teachers leave the field within five years of employment (Alliance for Education,…

  12. Persistence of airline accidents.

    PubMed

    Barros, Carlos Pestana; Faria, Joao Ricardo; Gil-Alana, Luis Alberiko

    2010-10-01

    This paper expands on air travel accident research by examining the relationship between air travel accidents and airline traffic or volume in the period from 1927-2006. The theoretical model is based on a representative airline company that aims to maximise its profits, and it utilises a fractional integration approach in order to determine whether there is a persistent pattern over time with respect to air accidents and air traffic. Furthermore, the paper analyses how airline accidents are related to traffic using a fractional cointegration approach. It finds that airline accidents are persistent and that a (non-stationary) fractional cointegration relationship exists between total airline accidents and airline passengers, airline miles and airline revenues, with shocks that affect the long-run equilibrium disappearing in the very long term. Moreover, this relation is negative, which might be due to the fact that air travel is becoming safer and there is greater competition in the airline industry. Policy implications are derived for countering accident events, based on competition and regulation. PMID:20618386

  13. Persistent Genital Arousal Disorder

    PubMed Central

    Aswath, Manju; Pandit, Lakshmi V.; Kashyap, Karthik; Ramnath, Raguram

    2016-01-01

    Persistent genital arousal disorder (PGAD) is a phenomenon, in which afflicted women experience spontaneous genital arousal, unresolved by orgasms and triggered by sexual or nonsexual stimuli, eliciting stress. The current case is a 40-year-old female who experienced such orgasms for about a month. Physical examination, investigations, and psychological testing were noncontributory. Carbamazepine (600 mg) was discontinued due to a lack of response. She improved significantly with supportive therapy. Various neuropsychological conditions, pelvic pathology, medications, etc., have been associated with this disorder. Pharmacologic strategies have included the use of antidepressants, antipsychotics, mood stabilizers, and analgesics. Validation, psycho-education, identifying triggers, distraction techniques, and pelvic massage have been tried. Living with PGAD is very demanding. There is a lack of understanding of the problem, shame, and hesitation to seek help. The syndrome has been recently described, and understanding is still evolving. PMID:27570347

  14. Acute and persistent diarrhea.

    PubMed

    Grimwood, Keith; Forbes, David A

    2009-12-01

    Socially disadvantaged Indigenous infants and children living in western industrialized countries experience high rates of infectious diarrhea, no more so than Aboriginal children from remote and rural regions of Northern Australia. Diarrheal disease, poor nutrition, and intestinal enteropathy reflect household crowding, inadequate water and poor sanitation and hygiene. Acute episodes of watery diarrhea are often best managed by oral glucose-electrolyte solutions with continuation of breastfeeding and early reintroduction of feeding. Selective use of lactose-free milk formula, short-term zinc supplementation and antibiotics may be necessary for ill children with poor nutrition, persistent symptoms, or dysentery. Education, high standards of environmental hygiene, breastfeeding, and immunization with newly licensed rotavirus vaccines are all needed to reduce the unacceptably high burden of diarrheal disease encountered in young children from Indigenous communities. PMID:19962025

  15. Caliber-Persistent Artery

    PubMed Central

    Costa, Sabrina Araújo Pinho; Ruiz, Marcelo Martinson; Kaba, Shajadi Pardo; Florezi, Giovanna Piacenza; Lemos Júnior, Celso Augusto; Witzel, Andréa Lusvarghi

    2015-01-01

    Caliber-persistent artery (CPLA) of the lip is a common vascular anomaly in which a main arterial branch extends to the surface of the mucous tissue with no reduction in its diameter. It usually manifests as pulsatile papule, is easily misdiagnosed, and is observed more frequently among older people, suggesting that its development may involve a degenerative process associated with aging; CPLA is also characterized by the loss of tone of the adjacent supporting connective tissue. Although the diagnosis is clinical, high-resolution Doppler ultrasound is a useful noninvasive tool for evaluating the lesion. This report describes the case of a 58-year-old male patient who complained of a lesion of the lower lip with bleeding and recurrent ulceration. The patient was successfully treated in our hospital after a diagnosis of CPLA and is currently undergoing a clinical outpatient follow-up with no complaints. PMID:26448884

  16. Epigenetic regulation of persistent pain

    PubMed Central

    Bai, Guang; Ren, Ke; Dubner, Ronald

    2014-01-01

    Persistent or chronic pain is tightly associated with various environmental changes and linked to abnormal gene expression within cells processing nociceptive signaling. Epigenetic regulation governs gene expression in response to environmental cues. Recent animal model and clinical studies indicate that epigenetic regulation plays an important role in the development/maintenance of persistent pain and, possibly the transition of acute pain to chronic pain, thus shedding light in a direction for development of new therapeutics for persistent pain. PMID:24948399

  17. Isolated persistent hypermethioninemia.

    PubMed Central

    Mudd, S H; Levy, H L; Tangerman, A; Boujet, C; Buist, N; Davidson-Mundt, A; Hudgins, L; Oyanagi, K; Nagao, M; Wilson, W G

    1995-01-01

    New information has been obtained on 30 patients with isolated persistent hypermethioninemia, most of them previously unreported. Biopsies to confirm the presumptive diagnosis of partially deficient activity of ATP: L-methionine S-adenosyltransferase (MAT; E.C.2.5.1.6) in liver were not performed on most of these patients. However, none showed the clinical findings or the extreme elevations of serum folate previously described in other patients with isolated hypermethioninemia considered not to have hepatic MAT deficiency. Patients ascertained on biochemical grounds had no neurological abnormalities, and 27/30 had IQs or Bayley development-index scores within normal limits or were judged to have normal mental development. Methionine transamination metabolites accumulated abnormally only when plasma methionine concentrations exceeded 300-350 microM and did so more markedly after 0.9 years of age. Data were obtained on urinary organic acids as well as plasma creatinine concentrations. Patterns of inheritance of isolated hypermethioninemia were variable. Considerations as to the optimal management of this group of patients are discussed. PMID:7573050

  18. Mixed Dementia

    MedlinePlus

    ... bodies , What Is Alzheimer's? NIA-Funded Memory & Aging Project Reveals Mixed Dementia Common Data from the first ... disease. For example, in the Memory and Aging Project study involving long-term cognitive assessments followed by ...

  19. Multidimensional persistence in biomolecular data.

    PubMed

    Xia, Kelin; Wei, Guo-Wei

    2015-07-30

    Persistent homology has emerged as a popular technique for the topological simplification of big data, including biomolecular data. Multidimensional persistence bears considerable promise to bridge the gap between geometry and topology. However, its practical and robust construction has been a challenge. We introduce two families of multidimensional persistence, namely pseudomultidimensional persistence and multiscale multidimensional persistence. The former is generated via the repeated applications of persistent homology filtration to high-dimensional data, such as results from molecular dynamics or partial differential equations. The latter is constructed via isotropic and anisotropic scales that create new simiplicial complexes and associated topological spaces. The utility, robustness, and efficiency of the proposed topological methods are demonstrated via protein folding, protein flexibility analysis, the topological denoising of cryoelectron microscopy data, and the scale dependence of nanoparticles. Topological transition between partial folded and unfolded proteins has been observed in multidimensional persistence. The separation between noise topological signatures and molecular topological fingerprints is achieved by the Laplace-Beltrami flow. The multiscale multidimensional persistent homology reveals relative local features in Betti-0 invariants and the relatively global characteristics of Betti-1 and Betti-2 invariants. PMID:26032339

  20. Metabolic aspects of bacterial persisters

    PubMed Central

    Prax, Marcel; Bertram, Ralph

    2014-01-01

    Persister cells form a multi-drug tolerant subpopulation within an isogenic culture of bacteria that are genetically susceptible to antibiotics. Studies with different Gram negative and Gram positive bacteria have identified a large number of genes associated with the persister state. In contrast, the revelation of persister metabolism has only been addressed recently. We here summarize metabolic aspects of persisters, which includes an overview about the bifunctional role of selected carbohydrates as both triggers for the exit from the drug tolerant state and metabolites which persisters feed on. Also alarmones as indicators for starvation have been shown to influence persister levels via different signaling cascades involving the activation of toxin-antitoxin systems and other regulatory factors. Finally, recent data obtained by 13C-isotopolog profiling demonstrated an active amino acid anabolism in Staphylococcus aureus cultures challenged with high drug concentrations. Understanding the metabolism of persister cells poses challenges but also paves the way for the development of anti-persister compounds. PMID:25374846

  1. Multidimensional persistence in biomolecular data

    PubMed Central

    Xia, Kelin; Wei, Guo-Wei

    2015-01-01

    Persistent homology has emerged as a popular technique for the topological simplification of big data, including biomolecular data. Multidimensional persistence bears considerable promise to bridge the gap between geometry and topology. However, its practical and robust construction has been a challenge. We introduce two families of multidimensional persistence, namely pseudo-multidimensional persistence and multiscale multidimensional persistence. The former is generated via the repeated applications of persistent homology filtration to high dimensional data, such as results from molecular dynamics or partial differential equations. The latter is constructed via isotropic and anisotropic scales that create new simiplicial complexes and associated topological spaces. The utility, robustness and efficiency of the proposed topological methods are demonstrated via protein folding, protein flexibility analysis, the topological denoising of cryo-electron microscopy data, and the scale dependence of nano particles. Topological transition between partial folded and unfolded proteins has been observed in multidimensional persistence. The separation between noise topological signatures and molecular topological fingerprints is achieved by the Laplace-Beltrami flow. The multiscale multidimensional persistent homology reveals relative local features in Betti-0 invariants and the relatively global characteristics of Betti-1 and Betti-2 invariants. PMID:26032339

  2. Energy landscapes and persistent minima

    NASA Astrophysics Data System (ADS)

    Carr, Joanne M.; Mazauric, Dorian; Cazals, Frédéric; Wales, David J.

    2016-02-01

    We consider a coarse-graining of high-dimensional potential energy landscapes based upon persistences, which correspond to lowest barrier heights to lower-energy minima. Persistences can be calculated efficiently for local minima in kinetic transition networks that are based on stationary points of the prevailing energy landscape. The networks studied here represent peptides, proteins, nucleic acids, an atomic cluster, and a glassy system. Minima with high persistence values are likely to represent some form of alternative structural morphology, which, if appreciably populated at the prevailing temperature, could compete with the global minimum (defined as infinitely persistent). Threshold values on persistences (and in some cases equilibrium occupation probabilities) have therefore been used in this work to select subsets of minima, which were then analysed to see how well they can represent features of the full network. Simplified disconnectivity graphs showing only the selected minima can convey the funnelling (including any multiple-funnel) characteristics of the corresponding full graphs. The effect of the choice of persistence threshold on the reduced disconnectivity graphs was considered for a system with a hierarchical, glassy landscape. Sets of persistent minima were also found to be useful in comparing networks for the same system sampled under different conditions, using minimum oriented spanning forests.

  3. Persistence, resistance, resonance

    NASA Astrophysics Data System (ADS)

    Tsadka, Maayan

    form of musical consumption and experience. The three pieces draw lines connecting different aspects of persistence, resistance, and resonance.

  4. Persistent Neuropathic Pain Influences Persistence Behavior in Rats

    PubMed Central

    Kniffin, Tracey C.; Danaher, Robert J.; Westlund, Karin N.; Ma, Fei; Miller, Craig S.; Carlson, Charles R.

    2016-01-01

    Aims To determine whether self-regulation can be studied successfully in a rodent model and whether persistent facial pain influences self-regulatory behavior. Methods Thirty male Sprague-Dawley rats, divided into two groups, (1) chronic constriction injury of the infraorbital nerve (CCI-ION) and (2) naïve, were used in a two-part behavioral paradigm of self-regulation. This paradigm consisted of both a cued go/no-go task (part one) and a persistence trial (part two). All animals were acclimated and trained for a period of 4 weeks prior to the experimental manipulation and then tested for a total of 5 weeks following experimental manipulation. Results were analyzed with t tests, one-way analysis of variance, and two-way, repeated measures analysis of variance. Results CCI-ION surgery induced significant mechanical hypersensitivity of the ipsilateral whisker pad that began 3 weeks postsurgery and persisted through the duration of the experiment (P < .001). At weeks 4 and 5 post–experimental manipulation, naïve animals demonstrated a significant decrease in lever presses during the persistence task (P < .05) compared to baseline, whereas CCI-ION animals did not (P = .55). Conclusion These results suggest that persistent pain influences behavioral regulation and that animals experiencing persistent pain may have difficulty adapting to environmental demands. PMID:25905537

  5. Immunomodulation by Persistent Organic Pollutants

    EPA Science Inventory

    Persistent organic pollutants (POPs) are widely distnbuted in the environment, are resistant to degradation, and increase in concentration (biomagnify) in the food chain. Concentrations in apical predators may be tens to hundreds of times greater than concentrations in their pref...

  6. Object-oriented persistent homology

    NASA Astrophysics Data System (ADS)

    Wang, Bao; Wei, Guo-Wei

    2016-01-01

    Persistent homology provides a new approach for the topological simplification of big data via measuring the life time of intrinsic topological features in a filtration process and has found its success in scientific and engineering applications. However, such a success is essentially limited to qualitative data classification and analysis. Indeed, persistent homology has rarely been employed for quantitative modeling and prediction. Additionally, the present persistent homology is a passive tool, rather than a proactive technique, for classification and analysis. In this work, we outline a general protocol to construct object-oriented persistent homology methods. By means of differential geometry theory of surfaces, we construct an objective functional, namely, a surface free energy defined on the data of interest. The minimization of the objective functional leads to a Laplace-Beltrami operator which generates a multiscale representation of the initial data and offers an objective oriented filtration process. The resulting differential geometry based object-oriented persistent homology is able to preserve desirable geometric features in the evolutionary filtration and enhances the corresponding topological persistence. The cubical complex based homology algorithm is employed in the present work to be compatible with the Cartesian representation of the Laplace-Beltrami flow. The proposed Laplace-Beltrami flow based persistent homology method is extensively validated. The consistence between Laplace-Beltrami flow based filtration and Euclidean distance based filtration is confirmed on the Vietoris-Rips complex for a large amount of numerical tests. The convergence and reliability of the present Laplace-Beltrami flow based cubical complex filtration approach are analyzed over various spatial and temporal mesh sizes. The Laplace-Beltrami flow based persistent homology approach is utilized to study the intrinsic topology of proteins and fullerene molecules. Based on a

  7. [Mixed marriages].

    PubMed

    Harmsen, C N

    1998-08-01

    The author examines the extent and characteristics of mixed marriages in the Netherlands. "Nine out of ten married persons born in Turkey or Morocco have a partner who was born in the same country. The majority of married Surinamese also have a partner originating from the same country. Those who spend (a part of) their youth in Indonesia (the former Dutch East Indies), on the other hand, are mostly married to someone born in the Netherlands." (EXCERPT) PMID:12294179

  8. Transmission and persistence of Ceratonova shasta genotypes in Chinook salmon.

    PubMed

    Hurst, Charlene N; Wong, Peter; Hallett, Sascha L; Ray, R Adam; Bartholomew, Jerri L

    2014-12-01

    Ceratonova shasta is a myxozoan parasite of salmon and trout transmitted by waterborne actinospores. Based on DNA sequence data and host specificity, 4 distinct parasite genotypes are recognized. Genotypes I and II are common in the lower reaches of the Klamath River, Oregon-California, but only infection by genotype I causes mortality in Chinook salmon. We conducted sentinel fish exposures and determined genotype composition in river water during exposure, and in fish gills, intestine, and tank water post-exposure to determine whether: (1) transmission of parasites having different genotypes is host-specific and (2) all transmitted genotypes persist in the host through to release as waterborne stages. Initial parasite transmission to the fish host appears indiscriminant, since we detected both genotypes I and II in 83.6% of the fish gills sampled. However, only genotype I was detected in fish that succumbed to infection, while both genotypes persisted in fish that survived. Persistence was likely dependent on exposure dose, initial infection type (mixed or single) and infection outcome (mortality or survival). The transmission of both genotypes to a majority of Chinook salmon and the persistence of multiple genotypes raises questions about how infection with mixed genotypes could result in within-host interactions that affect disease severity. PMID:24945751

  9. Mixed results with mixed disulfides.

    PubMed

    Brigelius-Flohé, Regina

    2016-04-01

    A period of research with Helmut Sies in the 1980s is recalled. Our experiments aimed at an in-depth understanding of metabolic changes due to oxidative challenges under near-physiological conditions, i.e. perfused organs. A major focus were alterations of the glutathione and the NADPH/NADP(+) system by different kinds of oxidants, in particular formation of glutathione mixed disulfides with proteins. To analyze mixed disulfides, a test was adapted which is widely used until today. The observations in perfused rat livers let us believe that glutathione-6-phosphate dehydrogenase (G6PDH), i.a. might be activated by glutathionylation. Although we did not succeed to verify this hypothesis for the special case of G6PDH, the regulation of enzyme/protein activities by glutathionylation today is an accepted posttranslational mechanism in redox biology in general. Our early experimental approaches are discussed in the context of present knowledge. PMID:27095221

  10. Measles virus persistence in an immortalized murine macrophage cell line.

    PubMed

    Goldman, M B; Buckthal, D J; Picciotto, S; O'Bryan, T A; Goldman, J N

    1995-02-20

    Persistent infection with the Edmonston strain of measles virus (MV) has been established in IC-21 cells, an immortalized murine macrophage cell line. Persistence was established immediately without syncytia formation or cytopathic effects. MV was expressed in the majority of the cells as evidenced by immunofluorescence microscopy, flow cytometry, infectious centers assays, and limiting dilution analysis. Hemagglutinin (H) and phosphoprotein expressed in persistently infected IC-21 cells had retarded migration in SDS-PAGE gels when compared to these proteins expressed in Vero cells. H protein differences were also found between freshly infected IC-21 cells and persistently infected IC-21 cells passaged for over 2 years. Six sublines of IC-21 cells, infected at different times, have maintained these characteristics for 2 years of passage. During this time period the intensity of immunofluorescence and the number of infectious virus particles recoverable fluctuated in five of the six cell lines. In one cell line virus expression remained at a consistent high level. The ability to establish a persistent MV infection in murine macrophages allows studies using a cell important in disseminating the infection. It facilitates experiments on immunological aspects of viral immunity by enabling cell mixing experiments with histocompatible cell populations and by making available the wide array of cellular and humoral reagents in the mouse. PMID:7871720

  11. Cytokines and persistent viral infections.

    PubMed

    Beltra, Jean-Christophe; Decaluwe, Hélène

    2016-06-01

    Intracellular pathogens such as the human immunodeficiency virus, hepatitis C and B or Epstein-Barr virus often cause chronic viral infections in humans. Persistence of these viruses in the host is associated with a dramatic loss of T-cell immune response due to functional T-cell exhaustion. Developing efficient immunotherapeutic approaches to prevent viral persistence and/or to restore a highly functional T-cell mediated immunity remains a major challenge. During the last two decades, numerous studies aimed to identify relevant host-derived factors that could be modulated to achieve this goal. In this review, we focus on recent advances in our understanding of the role of cytokines in preventing or facilitating viral persistence. We concentrate on the impact of multiple relevant cytokines in T-cell dependent immune response to chronic viral infection and the potential for using cytokines as therapeutic agents in mice and humans. PMID:26907634

  12. Non-Persisting Student Follow-Up.

    ERIC Educational Resources Information Center

    Willett, Lynn H.

    A survey was conducted to determine the characteristics and opinions of the non-persisting students at Moraine Valley Community College. A random sample of 500 non-persisting students was selected, with equal numbers of full-time and part-time ex-students. Separate questionnaires were used for non-persisting full-time and non-persisting part-time…

  13. Blood Persistent Organic Pollutants Level

    EPA Science Inventory

    This indicator describes the presence of a subset of persistent organic pollutants (POPs) in the blood of the U.S. population from 1999 to 2002. Some POPs have been linked to adverse health effects such as cancer and nervous system disorders. Three broad classes of POPs are in...

  14. Computational Methods to Model Persistence.

    PubMed

    Vandervelde, Alexandra; Loris, Remy; Danckaert, Jan; Gelens, Lendert

    2016-01-01

    Bacterial persister cells are dormant cells, tolerant to multiple antibiotics, that are involved in several chronic infections. Toxin-antitoxin modules play a significant role in the generation of such persister cells. Toxin-antitoxin modules are small genetic elements, omnipresent in the genomes of bacteria, which code for an intracellular toxin and its neutralizing antitoxin. In the past decade, mathematical modeling has become an important tool to study the regulation of toxin-antitoxin modules and their relation to the emergence of persister cells. Here, we provide an overview of several numerical methods to simulate toxin-antitoxin modules. We cover both deterministic modeling using ordinary differential equations and stochastic modeling using stochastic differential equations and the Gillespie method. Several characteristics of toxin-antitoxin modules such as protein production and degradation, negative autoregulation through DNA binding, toxin-antitoxin complex formation and conditional cooperativity are gradually integrated in these models. Finally, by including growth rate modulation, we link toxin-antitoxin module expression to the generation of persister cells. PMID:26468111

  15. Persistence Length of Stable Microtubules

    NASA Astrophysics Data System (ADS)

    Hawkins, Taviare; Mirigian, Matthew; Yasar, M. Selcuk; Ross, Jennifer

    2011-03-01

    Microtubules are a vital component of the cytoskeleton. As the most rigid of the cytoskeleton filaments, they give shape and support to the cell. They are also essential for intracellular traffic by providing the roadways onto which organelles are transported, and they are required to reorganize during cellular division. To perform its function in the cell, the microtubule must be rigid yet dynamic. We are interested in how the mechanical properties of stable microtubules change over time. Some ``stable'' microtubules of the cell are recycled after days, such as in the axons of neurons or the cilia and flagella. We measured the persistence length of freely fluctuating taxol-stabilized microtubules over the span of a week and analyzed them via Fourier decomposition. As measured on a daily basis, the persistence length is independent of the contour length. Although measured over the span of the week, the accuracy of the measurement and the persistence length varies. We also studied how fluorescently-labeling the microtubule affects the persistence length and observed that a higher labeling ratio corresponded to greater flexibility. National Science Foundation Grant No: 0928540 to JLR.

  16. Visual Persistence and Adult Dyslexia.

    ERIC Educational Resources Information Center

    Winters, Roberta L.; And Others

    1989-01-01

    Visual persistence was investigated in adults with and without dyslexia in order to determine whether dyslexic adults demonstrate problems similar to those found in childhood dyslexia. Results showed that sensitivity of dyslexic adults was impaired when parts of a test stimulus were presented to adjacent retinal areas, suggesting that under…

  17. Evolutionary dynamics for persistent cooperation in structured populations

    NASA Astrophysics Data System (ADS)

    Li, Yan; Liu, Xinsheng; Claussen, Jens Christian; Guo, Wanlin

    2015-06-01

    The emergence and maintenance of cooperative behavior is a fascinating topic in evolutionary biology and social science. The public goods game (PGG) is a paradigm for exploring cooperative behavior. In PGG, the total resulting payoff is divided equally among all participants. This feature still leads to the dominance of defection without substantially magnifying the public good by a multiplying factor. Much effort has been made to explain the evolution of cooperative strategies, including a recent model in which only a portion of the total benefit is shared by all the players through introducing a new strategy named persistent cooperation. A persistent cooperator is a contributor who is willing to pay a second cost to retrieve the remaining portion of the payoff contributed by themselves. In a previous study, this model was analyzed in the framework of well-mixed populations. This paper focuses on discussing the persistent cooperation in lattice-structured populations. The evolutionary dynamics of the structured populations consisting of three types of competing players (pure cooperators, defectors, and persistent cooperators) are revealed by theoretical analysis and numerical simulations. In particular, the approximate expressions of fixation probabilities for strategies are derived on one-dimensional lattices. The phase diagrams of stationary states, and the evolution of frequencies and spatial patterns for strategies are illustrated on both one-dimensional and square lattices by simulations. Our results are consistent with the general observation that, at least in most situations, a structured population facilitates the evolution of cooperation. Specifically, here we find that the existence of persistent cooperators greatly suppresses the spreading of defectors under more relaxed conditions in structured populations compared to that obtained in well-mixed populations.

  18. Kaposi's Sarcoma Herpesvirus Genome Persistence.

    PubMed

    Juillard, Franceline; Tan, Min; Li, Shijun; Kaye, Kenneth M

    2016-01-01

    Kaposi's sarcoma-associated herpesvirus (KSHV) has an etiologic role in Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. These diseases are most common in immunocompromised individuals, especially those with AIDS. Similar to all herpesviruses, KSHV infection is lifelong. KSHV infection in tumor cells is primarily latent, with only a small subset of cells undergoing lytic infection. During latency, the KSHV genome persists as a multiple copy, extrachromosomal episome in the nucleus. In order to persist in proliferating tumor cells, the viral genome replicates once per cell cycle and then segregates to daughter cell nuclei. KSHV only expresses several genes during latent infection. Prominent among these genes, is the latency-associated nuclear antigen (LANA). LANA is responsible for KSHV genome persistence and also exerts transcriptional regulatory effects. LANA mediates KSHV DNA replication and in addition, is responsible for segregation of replicated genomes to daughter nuclei. LANA serves as a molecular tether, bridging the viral genome to mitotic chromosomes to ensure that KSHV DNA reaches progeny nuclei. N-terminal LANA attaches to mitotic chromosomes by binding histones H2A/H2B at the surface of the nucleosome. C-terminal LANA binds specific KSHV DNA sequence and also has a role in chromosome attachment. In addition to the essential roles of N- and C-terminal LANA in genome persistence, internal LANA sequence is also critical for efficient episome maintenance. LANA's role as an essential mediator of virus persistence makes it an attractive target for inhibition in order to prevent or treat KSHV infection and disease. PMID:27570517

  19. The patch microstructure in concrete: effect of mixing time

    SciTech Connect

    Diamond, Sidney . E-Mail: diamond@ecn.purdue.edu

    2005-05-01

    It has been previously shown by backscatter-mode scanning electron microscopy (SEM) that various laboratory- and field-mixed concretes exhibit dense areas or patches of hardened cement paste (hcp) alternating with highly porous areas or patches. The present work represents an effort to establish whether this distinctive microstructure was a result of inadequate mixing. A conventional laboratory concrete was prepared and subjected to prolonged mixing in an efficient pan mixer, with small samples being removed periodically, compacted, and cured for 28 days. Examination indicated that evidences of the patchy microstructure persisted despite prolonged mixing for up to 30 min, far beyond normal concrete mixing times.

  20. Persistence and the Nikkei Index

    NASA Astrophysics Data System (ADS)

    Jain, S.; Yamano, T.

    2007-12-01

    The persistence phenomenon is studied in the Japanese financial market by using a novel mapping of the time evolution of the values of shares in a portfolio onto Ising spins. The method is applied to historical end of day data from the Japanese stock market over an arbitrarily chosen period. By studying the time dependence of the spins, we find clear evidence for a power law decay of the proportion of shares that remain either above or below their "starting" values. The results are compared with those resulting from data from the London market, where there is evidence of a distinctive double power law. Preliminary results from the Japanese market indicate similar behavior. We estimate a long time persistence exponent for the underlying financial markets to be 0.5.

  1. Global persistence in directed percolation

    NASA Astrophysics Data System (ADS)

    Oerding, K.; van Wijland, F.

    1998-08-01

    We consider a directed percolation process at its critical point. The probability that the deviation of the global order parameter with respect to its average has not changed its sign between 0 and t decays with t as a power law. In space dimensions 0305-4470/31/34/004/img5 the global persistence exponent 0305-4470/31/34/004/img6 that characterizes this decay is 0305-4470/31/34/004/img7 while for d<4 its value is increased to first order in 0305-4470/31/34/004/img8. Combining a method developed by Majumdar and Sire with renormalization group techniques we compute the correction to 0305-4470/31/34/004/img6 to first order in 0305-4470/31/34/004/img10. The global persistence exponent is found to be a new and independent exponent. Finally we compare our results with existing simulations.

  2. Persistent Monitoring Platforms Final Report

    SciTech Connect

    Bennett, C L

    2007-02-22

    This project was inspired and motivated by the need to provide better platforms for persistent surveillance. In the years since the inception of this work, the need for persistence of surveillance platforms has become even more widely appreciated, both within the defense community and the intelligence community. One of the most demanding technical requirements for such a platform involves the power plant and energy storage system, and this project concentrated almost exclusively on the technology associated with this system for a solar powered, high altitude, unmanned aircraft. An important realization for the feasibility of such solar powered aircraft, made at the outset of this project, was that thermal energy may be stored with higher specific energy density than for any other known practical form of rechargeable energy storage. This approach has proved to be extraordinarily fruitful, and a large number of spin-off applications of this technology were developed in the course of this project.

  3. Persistent Patterns in Accretion Disks

    SciTech Connect

    Amin, Mustafa A.; Frolov, Andrei V.; /KIPAC, Menlo Park

    2006-04-03

    We present a set of new characteristic frequencies associated with accretion disks around compact objects. These frequencies arise from persistent rotating patterns in the disk that are finite in radial extent and driven purely by the gravity of the central body. Their existence depends on general relativistic corrections to orbital motion and, if observed, could be used to probe the strong gravity region around a black hole. We also discuss a possible connection to the puzzle of quasi-periodic oscillations.

  4. Divergence in sink contributions to population persistence

    EPA Science Inventory

    Population sinks present unique conservation challenges. The loss of animals in sinks can compromise persistence. Conversely, sinks can bolster population sizes, improving viability. To assess the contribution of sinks to regional persistence, we simulated the removal of sink hab...

  5. Dealing with Persistent Pain in Older Adults

    MedlinePlus

    ... Pain Management Related Documents PDF Dealing with Persistent Pain in Later Life Download Join our e-newsletter! Resources Dealing with Persistent Pain in Older Adults Tools and Tips Printer-friendly ...

  6. Bilateral persistent pupillary membranes associated with cataract

    PubMed Central

    Ahmad, Syed Shoeb; Binson, Caroline; Lung, Chong Ka; Ghani, Shuaibah Abdul

    2011-01-01

    Summary Exuberant persistent pupillary membranes (PPM) are rare in adult eyes. We report the case of a 53-year-old man diagnosed with bilateral, profuse, persistent pupillary membranes and unilateral cataract. PMID:23362401

  7. MOOCs and Persistence: Definitions and Predictors

    ERIC Educational Resources Information Center

    Evans, Brent J.; Baker, Rachel B.

    2016-01-01

    The chapter argues for redefining the term "persistence" as it relates to MOOCs and considers how different measures produce different results in the research; it closes with a review of research on persistence in MOOCs.

  8. High Persister Mutants in Mycobacterium tuberculosis

    PubMed Central

    Torrey, Heather L.; Keren, Iris; Via, Laura E.; Lee, Jong Seok; Lewis, Kim

    2016-01-01

    Mycobacterium tuberculosis forms drug-tolerant persister cells that are the probable cause of its recalcitrance to antibiotic therapy. While genetically identical to the rest of the population, persisters are dormant, which protects them from killing by bactericidal antibiotics. The mechanism of persister formation in M. tuberculosis is not well understood. In this study, we selected for high persister (hip) mutants and characterized them by whole genome sequencing and transcriptome analysis. In parallel, we identified and characterized clinical isolates that naturally produce high levels of persisters. We compared the hip mutants obtained in vitro with clinical isolates to identify candidate persister genes. Genes involved in lipid biosynthesis, carbon metabolism, toxin-antitoxin systems, and transcriptional regulators were among those identified. We also found that clinical hip isolates exhibited greater ex vivo survival than the low persister isolates. Our data suggest that M. tuberculosis persister formation involves multiple pathways, and hip mutants may contribute to the recalcitrance of the infection. PMID:27176494

  9. High Persister Mutants in Mycobacterium tuberculosis.

    PubMed

    Torrey, Heather L; Keren, Iris; Via, Laura E; Lee, Jong Seok; Lewis, Kim

    2016-01-01

    Mycobacterium tuberculosis forms drug-tolerant persister cells that are the probable cause of its recalcitrance to antibiotic therapy. While genetically identical to the rest of the population, persisters are dormant, which protects them from killing by bactericidal antibiotics. The mechanism of persister formation in M. tuberculosis is not well understood. In this study, we selected for high persister (hip) mutants and characterized them by whole genome sequencing and transcriptome analysis. In parallel, we identified and characterized clinical isolates that naturally produce high levels of persisters. We compared the hip mutants obtained in vitro with clinical isolates to identify candidate persister genes. Genes involved in lipid biosynthesis, carbon metabolism, toxin-antitoxin systems, and transcriptional regulators were among those identified. We also found that clinical hip isolates exhibited greater ex vivo survival than the low persister isolates. Our data suggest that M. tuberculosis persister formation involves multiple pathways, and hip mutants may contribute to the recalcitrance of the infection. PMID:27176494

  10. Dynamically Induced Displacements of a Persistent Cold-Air Pool

    NASA Astrophysics Data System (ADS)

    Lareau, Neil P.; Horel, John D.

    2015-02-01

    We examine the influence of a passing weather system on a persistent cold-air pool (CAP) during the Persistent Cold-Air Pool Study in the Salt Lake Valley, Utah, USA. The CAP experiences a sequence of along-valley displacements that temporarily and partially remove the cold air in response to increasing along-valley winds aloft. The displacements are due to the formation of a mountain wave over the upstream topography as well as adjustments to the regional horizontal pressure gradient and wind-stress divergence acting on the CAP. These processes appear to help establish a balance wherein the depth of the CAP increases to the north. When that balance is disrupted, the CAP tilt collapses, which sends a gravity current of cold air travelling upstream and thereby restores CAP conditions throughout the valley. Intra-valley mixing of momentum, heat, and pollution within the CAP by Kelvin-Helmholtz waves and seiching is also examined.

  11. Persistence and Attrition at San Juan College.

    ERIC Educational Resources Information Center

    Moore, Nelle

    A project was undertaken at San Juan College, in New Mexico, to examine findings from several studies of student persistence and retention to shed light on factors influencing persistence at the college. The project took into account several definitions of persistence, including re-enrollment in the subsequent semester (semester to semester),…

  12. Persistence-Retention. Snapshot™ Report, Spring 2014

    ERIC Educational Resources Information Center

    National Student Clearinghouse, 2014

    2014-01-01

    This snapshot report provides information on student persistence and retention rates for Spring 2014. Data is presented in tabular format on the following: (1) First-Year Persistence and Retention Rates by Starting Enrollment Intensity (all institutional sectors); (2) First-Year Persistence and Retention Rates by Age at College Entry (all…

  13. Persistence-Retention. Snapshot™ Report, Spring 2015

    ERIC Educational Resources Information Center

    National Student Clearinghouse, 2015

    2015-01-01

    This Snapshot Report offers information on student persistence and retention rates for 2009-2013. It offers data on the following: (1) First-Year Persistence and Retention Rates for Students Who Start College at Four-Year Private Nonprofit Institutions; (2) First-Year Persistence and Retention Rates for Students Who Start College at Four-Year…

  14. Intent to Persist at Religiously Affiliated Universities

    ERIC Educational Resources Information Center

    Sansom, J. Mel

    2012-01-01

    The purpose of the secondary data analysis was to examine the attributes of students who intend to persist at the same religiously affiliated institution. The review of literature indicated that persistence has been studied extensively, but there has been only limited investigation of persistence focused on religiously affiliated institutions. The…

  15. Does Motivation Affect Performance via Persistence?

    ERIC Educational Resources Information Center

    Vollmeyer, Regina; Rheinberg, Falko

    2000-01-01

    Studied the relationships among motivation, persistence, and performance in a sample of 51 German college students. Path analysis showed that initial motivation influenced persistence but that the relationship between persistence and performance was disrupted because learners with more knowledge stopped sooner. (SLD)

  16. The Extraction of Information From Visual Persistence

    ERIC Educational Resources Information Center

    Erwin, Donald E.

    1976-01-01

    This research sought to distinguish among three concepts of visual persistence by substituting the physical presence of the target stimulus while simultaneously inhibiting the formation of a persisting representation. Reportability of information about the stimuli was compared to a condition in which visual persistence was allowed to fully develop…

  17. A Grounded Theory of Adult Student Persistence

    ERIC Educational Resources Information Center

    Capps, Rosemary

    2010-01-01

    This grounded theory study investigates adult student persistence at a community college. Student persistence in college is a prerequisite for degree achievement, which correlates with higher earnings and overall better quality of life. Persistence rates remain low for adult students, who combine their college endeavors with responsibilities to…

  18. On Persistence in Multiobjective Oligopoly

    NASA Astrophysics Data System (ADS)

    Ahmed, E.; Hegazi, A. S.; El-Hafez, A. T. Abd

    Multiobjective oligopoly models are constructed. The objective of th e first two models are to maximize profits and to maximize sales. In the third model, the objectives are to maximize profits and to minimize risk. Giving more weight to risk minimization decreased the profits. In all the three models, we found that the weight of the profit maximization has to be higher than a given threshold. Sufficient conditions for persistence of some multiobjective oligopolies are derived. Again, they require that the weight of profit maximization to be higher than certain value.

  19. Housing Mix, School Mix: Barriers to Success

    ERIC Educational Resources Information Center

    Camina, M. M.; Iannone, P.

    2014-01-01

    Recent UK policy has emphasised both the development of socially mixed communities and the creation of balanced school intakes. In this paper, we use a case study of an area of mixed tenure in eastern England to explore policy in practice and the extent to which mechanisms of segregation impact on both the creation of socially mixed neighbourhoods…

  20. Behavior and persistence of spilled oil on shoreline

    SciTech Connect

    Michel, J. )

    1991-03-01

    Recent oil spills have re-demonstrated the range of shoreline impacts that are possible from medium to large spills in the United States, i.e., the Exxon Valdez spill which significantly contaminated over 1000 km of shoreline in Alaska and the Mega Borg, which resulted in widely scattered tar balls over a small area. Immediate and total removal of stranded oil should not always be the primary objective. Instead, shoreline cleanup strategies developed for oil spills need to consider the persistence and short- to long-term persistence of stranded oil. There are several general guidelines on the persistence of stranded oil. High-energy shorelines are rapidly and effectively cleaned by natural processes, although there are micro-environments where oil tends to persist (wave shadows, supratidal zone, rock crevices, etc.). On sand and mixed sand and gravel beaches, oil tends to be buried below clean layers of sediment, but erosional/depositional cycles will result in oil removal, usually within one year. In sheltered environments (wetlands, tidal flats) oil will persist for long periods; therefore, oil removal is frequently required, though it is usually poorly implemented. Cobble/boulder beaches, while usually very complex, present a special problem. They can be found in a range of energy settings, with years between periods of storm activity. These beaches can hold large volumes of oil; they can be a source of long-term ({gt} one year) leaching and sheening; subsurface oil is very difficult to remove by surface treatment methods; and they have poorly understood sedimentation patterns, so it is difficult to predict rates of sediment reworking. Studies of recent oil spills have shown a need for shoreline-specific technologies for these types of beaches.

  1. Mixing and Transport.

    PubMed

    Chang, Chein-Chi; Chapman, Tom; Siverts-Wong, Elena; Wei, Li; Mei, Ying

    2016-10-01

    This section covers research published during the calendar year 2015 on mixing and transport processes. The review covers mixing of anaerobic digesters, mixing of heat transfer, and environmental fate and transport. PMID:27620101

  2. Long-persistence blue phosphors

    NASA Technical Reports Server (NTRS)

    Yen, William M. (Inventor); Jia, Weiyi (Inventor); Lu, Lizhu (Inventor); Yuan, Huabiao (Inventor)

    2000-01-01

    This invention relates to phosphors including long-persistence blue phosphors. Phosphors of the invention are represented by the general formula: MO . mAl.sub.2 O.sub.3 :Eu.sup.2+,R.sup.3+ wherein m is a number ranging from about 1.6 to about 2.2, M is Sr or a combination of Sr with Ca and Ba or both, R.sup.3+ is a trivalent metal ion or trivalent Bi or a mixture of these trivalent ions, Eu.sup.2+ is present at a level up to about 5 mol % of M, and R.sup.3+ is present at a level up to about 5 mol % of M. Phosphors of this invention include powders, ceramics, single crystals and single crystal fibers. A method of manufacturing improved phosphors and a method of manufacturing single crystal phosphors are also provided.

  3. Persistent Pneumonia in an Infant

    PubMed Central

    Padilla, Kristen; Logan, Latania; Codispoti, Christopher; Jones, Carolyn

    2015-01-01

    A 4-month-old boy with past medical history of eczema presented with fever and cough; a chest radiograph showed lung consolidation, and he was initially treated with amoxicillin for presumed community-acquired pneumonia. After several days, his fever persisted. He was also profoundly anemic. Antibiotic coverage was broadened because of the concern for resistant organisms; he began to improve and was discharged from the hospital. However, at 5 months of age, his fever returned, and he continued to demonstrate lung consolidation on chest radiograph. Additionally, he had lost weight and continued to be anemic. Splenic cysts were noted on abdominal ultrasound. He was diagnosed with an unusual etiology for his pneumonia and improved with the appropriate therapy. An underlying immunodeficiency was suspected, but initial testing was nondiagnostic. At 12 months of age, he presented with another infection, and the final diagnosis was made. PMID:26122810

  4. Persistent homology and string vacua

    NASA Astrophysics Data System (ADS)

    Cirafici, Michele

    2016-03-01

    We use methods from topological data analysis to study the topological features of certain distributions of string vacua. Topological data analysis is a multi-scale approach used to analyze the topological features of a dataset by identifying which homological characteristics persist over a long range of scales. We apply these techniques in several contexts. We analyze {N}=2 vacua by focusing on certain distributions of Calabi-Yau varieties and Landau-Ginzburg models. We then turn to flux compactifications and discuss how we can use topological data analysis to extract physical information. Finally we apply these techniques to certain phenomenologically realistic heterotic models. We discuss the possibility of characterizing string vacua using the topological properties of their distributions.

  5. Persistent nicorandil induced oral ulceration

    PubMed Central

    Healy, C M; Smyth, Y; Flint, S R

    2004-01-01

    Four patients with nicorandil induced ulceration are described, and the literature on the subject is reviewed. Nicorandil induced ulcers are very painful and distressing for patients. Clinically they appear as large, deep, persistent ulcers that have punched out edges. They are poorly responsive to topical steroids and usually require alteration of nicorandil treatment. The ulceration tends to occur at high doses of nicorandil and all four cases reported here were on doses of 40 mg per day or greater. In these situations reduction of nicorandil dose may be sufficient to promote ulcer healing and prevent further recurrence. However, nicorandil induced ulcers have been reported at doses as low as 10 mg daily and complete cessation of nicorandil may be required. PMID:15201264

  6. Mixed connective tissue disease.

    PubMed

    Gunnarsson, Ragnar; Hetlevik, Siri Opsahl; Lilleby, Vibke; Molberg, Øyvind

    2016-02-01

    The concept of mixed connective tissue disease (MCTD) as a separate connective tissue disease (CTD) has persisted for more than four decades. High titers of antibodies targeting the U1 small nuclear ribonucleoprotein particle (U1 snRNP) in peripheral blood are a sine qua non for the diagnosis of MCTD, in addition to distinct clinical features including Raynaud's phenomenon (RP), "puffy hands," arthritis, myositis, pleuritis, pericarditis, interstitial lung disease (ILD), and pulmonary hypertension (PH). Recently, population-based epidemiology data from Norway estimated the point prevalence of adult-onset MCTD to be 3.8 per 100,000 and the mean annual incidence to be 2.1 per million per year, supporting the notion that MCTD is the least common CTD. Little is known about the etiology of MCTD, but recent genetic studies have confirmed that MCTD is a strongly HLA (​human leukocyte antigen)-linked disease, as the HLA profiles of MCTD differ distinctly from the corresponding profiles of ethnically matched healthy controls and other CTDs. In the first section of this review, we provide an update on the clinical, immunological, and genetic features of MCTD and discuss the relationship between MCTD and the other CTDs. Then we proceed to discuss the recent advances in therapy and our current understanding of prognosis and prognostic factors, especially those that are associated with the more serious pulmonary and cardiovascular complications of the disease. In the final section, we discuss some of the key, unresolved questions related to anti-RNP-associated diseases and indicate how these questions may be approached in future studies. PMID:27421219

  7. Persistent primitive trigeminal artery: a review.

    PubMed

    Azab, Waleed; Delashaw, Johnny; Mohammed, Mohammed

    2012-01-01

    The trigeminal artery is the largest of the fetal carotid-basilar anastomotic arteries, and it persists for the longest embryonic period. The artery usually involutes after the development of the posterior communicating artery. The exact causes of persistence of this primitive vessel into adulthood are not completely clear. Angiographic and anatomical descriptions of the various persistent trigeminal artery (PTA) configurations and their relation to the remainder of the cerebrovascular tree and the other surrounding structures have been reported. Persistent trigeminal artery can be associated with many other vascular anomalies and disorders including aneurysms, arteriovenous malformations and carotid-cavernous fistulae. A thorough understanding of the anatomical and angiographic features of this persistent embryonic arterial channel is of utmost importance when making therapeutic decisions and embarking on surgical or endovascular intervention for any pertinent pathological condition. We review the embryology, angiographic features, microsurgical anatomy and associated vascular anomalies and disorders of the persistent trigeminal artery. PMID:22843453

  8. A Historical Perspective on Bacterial Persistence.

    PubMed

    Verstraeten, Natalie; Knapen, Wouter; Fauvart, Maarten; Michiels, Jan

    2016-01-01

    Bactericidal antibiotics quickly kill the majority of a bacterial population. However, a small fraction of cells typically survive through entering the so-called persister state. Persister cells are increasingly being viewed as a major cause of the recurrence of chronic infectious disease and could be an important factor in the emergence of antibiotic resistance. The phenomenon of persistence was first described in the 1940s, but remained poorly understood for decades afterwards. Only recently, a series of breakthrough discoveries has started to shed light on persister physiology and the molecular and genetic underpinnings of persister formation. We here provide an overview of the key studies that have paved the way for the current boom in persistence research, with a special focus on the technological and methodological advances that have enabled this progress. PMID:26468095

  9. Dualities in Persistent (Co)Homology

    SciTech Connect

    de Silva, Vin; Morozov, Dmitriy; Vejdemo-Johansson, Mikael

    2011-09-16

    We consider sequences of absolute and relative homology and cohomology groups that arise naturally for a filtered cell complex. We establishalgebraic relationships between their persistence modules, and show that they contain equivalent information. We explain how one can use the existingalgorithm for persistent homology to process any of the four modules, and relate it to a recently introduced persistent cohomology algorithm. Wepresent experimental evidence for the practical efficiency of the latter algorithm.

  10. Science Identity's Influence on Community College Students' Engagement, Persistence, and Performance in Biology

    NASA Astrophysics Data System (ADS)

    Riccitelli, Melinda

    In the United States (U.S.), student engagement, persistence, and academic performance levels in college science, technology, engineering, and mathematics (STEM) programs have been unsatisfactory over the last decade. Low student engagement, persistence, and academic performance in STEM disciplines have been identified as major obstacles to U.S. economic goals and U.S. science education objectives. The central and salient science identity a college student claims can influence his engagement, persistence, and academic achievement in college science. While science identity studies have been conducted on four-year college populations there is a gap in the literature concerning community college students' science identity and science performance. The purpose of this quantitative correlational study was to examine the relationship between community college students claimed science identities and engagement, persistence, and academic performance. A census sample of 264 community college students enrolled in biology during the summer of 2015 was used to study this relationship. Science identity and engagement levels were calculated using the Science Identity Centrality Scale and the Biology Motivation Questionnaire II, respectively. Persistence and final grade data were collected from institutional and instructor records. Engagement significantly correlated to, r =.534, p = .01, and varied by science identity, p < .001. Percent final grade also varied by science identity (p < .005), but this relationship was weaker (r = .208, p = .01). Results for science identity and engagement and final grade were consistent with the identity literature. Persistence did not vary by science identity in this student sample (chi2 =2.815, p = .421). This result was inconsistent with the literature on science identity and persistence. Quantitative results from this study present a mixed picture of science identity status at the community college level. It is suggested, based on the findings

  11. High turnover drives prolonged persistence of influenza in managed pig herds

    PubMed Central

    Aguas, Ricardo; Riley, Steven; Loeffen, Willie L. A.; Wood, James L. N.; Grenfell, Bryan T.

    2016-01-01

    Pigs have long been hypothesized to play a central role in the emergence of novel human influenza A virus (IAV) strains, by serving as mixing vessels for mammalian and avian variants. However, the key issue of viral persistence in swine populations at different scales is ill understood. We address this gap using epidemiological models calibrated against seroprevalence data from Dutch finishing pigs to estimate the ‘critical herd size’ (CHS) for IAV persistence. We then examine the viral phylogenetic evidence for persistence by comparing human and swine IAV. Models suggest a CHS of approximately 3000 pigs above which influenza was likely to persist, i.e. orders of magnitude lower than persistence thresholds for IAV and other acute viruses in humans. At national and regional scales, we found much stronger empirical signatures of prolonged persistence of IAV in swine compared with human populations. These striking levels of persistence in small populations are driven by the high recruitment rate of susceptible piglets, and have significant implications for management of swine and for overall patterns of genetic diversity of IAV. PMID:27358277

  12. High turnover drives prolonged persistence of influenza in managed pig herds.

    PubMed

    Pitzer, Virginia E; Aguas, Ricardo; Riley, Steven; Loeffen, Willie L A; Wood, James L N; Grenfell, Bryan T

    2016-06-01

    Pigs have long been hypothesized to play a central role in the emergence of novel human influenza A virus (IAV) strains, by serving as mixing vessels for mammalian and avian variants. However, the key issue of viral persistence in swine populations at different scales is ill understood. We address this gap using epidemiological models calibrated against seroprevalence data from Dutch finishing pigs to estimate the 'critical herd size' (CHS) for IAV persistence. We then examine the viral phylogenetic evidence for persistence by comparing human and swine IAV. Models suggest a CHS of approximately 3000 pigs above which influenza was likely to persist, i.e. orders of magnitude lower than persistence thresholds for IAV and other acute viruses in humans. At national and regional scales, we found much stronger empirical signatures of prolonged persistence of IAV in swine compared with human populations. These striking levels of persistence in small populations are driven by the high recruitment rate of susceptible piglets, and have significant implications for management of swine and for overall patterns of genetic diversity of IAV. PMID:27358277

  13. Unrelated toxin-antitoxin systems cooperate to induce persistence.

    PubMed

    Fasani, Rick A; Savageau, Michael A

    2015-07-01

    non-growing cells, typical of persisters, that exist under normal conditions, rather than only as an induced response. The frequency of persisters in the population can be tuned for a particular environmental niche by mixing and matching unrelated systems via mutation, horizontal gene transfer and selection. PMID:26063817

  14. A PILOT STUDY OF CHILDREN'S TOTAL EXPOSURE TO PERSISTENT PESTICIDES AND OTHER PERSISTENT ORGANIC POLLUTANTS (CTEPP)

    EPA Science Inventory

    The Pilot Study of Children's Total Exposure to Persistent Pesticides and Other Persistent Organic Pollutants (CTEPP) investigated the aggregate exposures of 257 preschool children and their primary adult caregivers to pollutants commonly detected in their everyday environments. ...

  15. Personality Characteristics in Relation to College Persistence

    ERIC Educational Resources Information Center

    Johnson, Duane E.

    1970-01-01

    Scales of the Minnesota Counseling Inventory (MCI) were used to compare persisters with nonpersisters. All four comparisons involving the Conformity scale and two of four comparisons involving the Family Relationships scale demonstrated significant differences. Persisters scored lower than nonpersisters on all comparisons involving the Conformity…

  16. Long Persistent Light Emitting Diode Indicators

    ERIC Educational Resources Information Center

    Jia, Dongdong; Ma, Yiwei; Hunter, D. N.

    2007-01-01

    An undergraduate laboratory was designed for undergraduate students to make long persistent light emitting diode (LED) indicators using phosphors. Blue LEDs, which emit at 465 nm, were characterized and used as an excitation source. Long persistent phosphors, SrAl[subscript 2]O[subscript 4]:Eu[superscript 2+],Dy[superscript 3+] (green) and…

  17. Supplemental Instruction: Supporting Persistence in Barrier Courses

    ERIC Educational Resources Information Center

    Bronstein, Susan B.

    2008-01-01

    Courses that interfere with undergraduate students' persistence are barriers that appear all along the undergraduate continuum. Supplemental Instruction (SI) may contribute to students' achievement in a barrier course and, therefore, to their persistence in their academic program. The purpose of this single-case descriptive study was to explore…

  18. Genetic Mapping of Persistence in Tetraploid Alfalfa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Persistence is a critical trait for alfalfa, yet the genetics of this trait is poorly understood. Herein, we characterize an F1 alfalfa population derived from the cross between the two cultivated alfalfa subpecies for persistence in three production seasons at Ames and Nashua, Iowa locations and o...

  19. Persistence of Grazed Red Clover Varieties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Historically, red clover (Trifolium pratense) has been limited by its lack of stand persistence in hay and grazed systems compared to other small-seeded forage legumes. Breeding over the past 50 years has extended red clover persistence in a hay management system to four years. This study examined g...

  20. Counseling on Campus: Client Persistence and Progress

    ERIC Educational Resources Information Center

    Lucas, Margaretha S.

    2012-01-01

    Two related studies addressed college students' persistence and progress in psychotherapy. In Study 1, using emotional health variables assessed at intake, students who persisted in counseling and demonstrated clinical improvement were compared with those who either did not return for their first session or who did return but stopped before…

  1. Type I Interferon Receptor Deficiency in Dendritic Cells Facilitates Systemic Murine Norovirus Persistence Despite Enhanced Adaptive Immunity

    PubMed Central

    Nice, Timothy J.; Osborne, Lisa C.; Tomov, Vesselin T.; Artis, David; Wherry, E. John; Virgin, Herbert W.

    2016-01-01

    In order for a virus to persist, there must be a balance between viral replication and immune clearance. It is commonly believed that adaptive immunity drives clearance of viral infections and, thus, dysfunction or viral evasion of adaptive immunity is required for a virus to persist. Type I interferons (IFNs) play pleiotropic roles in the antiviral response, including through innate control of viral replication. Murine norovirus (MNoV) replicates in dendritic cells (DCs) and type I IFN signaling in DCs is important for early control of MNoV replication. We show here that the non-persistent MNoV strain CW3 persists systemically when CD11c positive DCs are unable to respond to type I IFN. Persistence in this setting is associated with increased early viral titers, maintenance of DC numbers, increased expression of DC activation markers and an increase in CD8 T cell and antibody responses. Furthermore, CD8 T cell function is maintained during the persistent phase of infection and adaptive immune cells from persistently infected mice are functional when transferred to Rag1-/- recipients. Finally, increased early replication and persistence are also observed in mixed bone marrow chimeras where only half of the CD11c positive DCs are unable to respond to type I IFN. These findings demonstrate that increased early viral replication due to a cell-intrinsic innate immune deficiency is sufficient for persistence and a functional adaptive immune response is not sufficient for viral clearance. PMID:27327515

  2. Reprogramming of Yersinia from Virulent to Persistent Mode Revealed by Complex In Vivo RNA-seq Analysis

    PubMed Central

    Avican, Kemal; Fahlgren, Anna; Huss, Mikael; Heroven, Ann Kathrin; Beckstette, Michael; Dersch, Petra; Fällman, Maria

    2015-01-01

    We recently found that Yersinia pseudotuberculosis can be used as a model of persistent bacterial infections. We performed in vivo RNA-seq of bacteria in small cecal tissue biopsies at early and persistent stages of infection to determine strategies associated with persistence. Comprehensive analysis of mixed RNA populations from infected tissues revealed that Y. pseudotuberculosis undergoes transcriptional reprogramming with drastic down-regulation of T3SS virulence genes during persistence when the pathogen resides within the cecum. At the persistent stage, the expression pattern in many respects resembles the pattern seen in vitro at 26oC, with for example, up-regulation of flagellar genes and invA. These findings are expected to have impact on future rationales to identify suitable bacterial targets for new antibiotics. Other genes that are up-regulated during persistence are genes involved in anaerobiosis, chemotaxis, and protection against oxidative and acidic stress, which indicates the influence of different environmental cues. We found that the Crp/CsrA/RovA regulatory cascades influence the pattern of bacterial gene expression during persistence. Furthermore, arcA, fnr, frdA, and wrbA play critical roles in persistence. Our findings suggest a model for the life cycle of this enteropathogen with reprogramming from a virulent to an adapted phenotype capable of persisting and spreading by fecal shedding. PMID:25590628

  3. Type I Interferon Receptor Deficiency in Dendritic Cells Facilitates Systemic Murine Norovirus Persistence Despite Enhanced Adaptive Immunity.

    PubMed

    Nice, Timothy J; Osborne, Lisa C; Tomov, Vesselin T; Artis, David; Wherry, E John; Virgin, Herbert W

    2016-06-01

    In order for a virus to persist, there must be a balance between viral replication and immune clearance. It is commonly believed that adaptive immunity drives clearance of viral infections and, thus, dysfunction or viral evasion of adaptive immunity is required for a virus to persist. Type I interferons (IFNs) play pleiotropic roles in the antiviral response, including through innate control of viral replication. Murine norovirus (MNoV) replicates in dendritic cells (DCs) and type I IFN signaling in DCs is important for early control of MNoV replication. We show here that the non-persistent MNoV strain CW3 persists systemically when CD11c positive DCs are unable to respond to type I IFN. Persistence in this setting is associated with increased early viral titers, maintenance of DC numbers, increased expression of DC activation markers and an increase in CD8 T cell and antibody responses. Furthermore, CD8 T cell function is maintained during the persistent phase of infection and adaptive immune cells from persistently infected mice are functional when transferred to Rag1-/- recipients. Finally, increased early replication and persistence are also observed in mixed bone marrow chimeras where only half of the CD11c positive DCs are unable to respond to type I IFN. These findings demonstrate that increased early viral replication due to a cell-intrinsic innate immune deficiency is sufficient for persistence and a functional adaptive immune response is not sufficient for viral clearance. PMID:27327515

  4. Mixing in explosions

    SciTech Connect

    Kuhl, A.L.

    1993-12-01

    Explosions always contain embedded turbulent mixing regions, for example: boundary layers, shear layers, wall jets, and unstable interfaces. Described here is one particular example of the latter, namely, the turbulent mixing occurring in the fireball of an HE-driven blast wave. The evolution of the turbulent mixing was studied via two-dimensional numerical simulations of the convective mixing processes on an adaptive mesh. Vorticity was generated on the fireball interface by baroclinic effects. The interface was unstable, and rapidly evolved into a turbulent mixing layer. Four phases of mixing were observed: (1) a strong blast wave phase; (2) and implosion phase; (3) a reshocking phase; and (4) an asymptotic mixing phase. The flowfield was azimuthally averaged to evaluate the mean and r.m.s. fluctuation profiles across the mixing layer. The vorticity decayed due to a cascade process. This caused the corresponding enstrophy parameter to increase linearly with time -- in agreement with homogeneous turbulence calculations of G.K. Batchelor.

  5. Mixing in astrophysics

    SciTech Connect

    Fryer, Christopher Lee

    2011-01-07

    Turbulent mixing plays a vital role in many fields in astronomy. Here I review a few of these sites, discuss the importance of this turbulent mixing and the techniques used by astrophysicists to solve these problems.

  6. Laboratory diagnosis of persistent human chlamydial infection

    PubMed Central

    Puolakkainen, Mirja

    2013-01-01

    Diagnostic assays for persistent chlamydial infection are much needed to conduct high-quality, large-scale studies investigating the persistent state in vivo, its disease associations and the response to therapy. Yet in most studies the distinction between acute and persistent infection is based on the interpretation of the data obtained by the assays developed to diagnose acute infections or on complex assays available for research only and/or difficult to establish for clinical use. Novel biomarkers for detection of persistent chlamydial infection are urgently needed. Chlamydial whole genome proteome arrays are now available and they can identify chlamydial antigens that are differentially expressed between acute infection and persistent infection. Utilizing these data will lead to the development of novel diagnostic assays. Carefully selected specimens from well-studied patient populations are clearly needed in the process of translating the proteomic data into assays useful for clinical practice. Before such antigens are identified and validated assays become available, we face a challenge of deciding whether the persistent infection truly induced appearance of the proposed marker or do we just base our diagnosis of persistent infection on the presence of the suggested markers. Consequently, we must bear this in mind when interpreting the available data. PMID:24381934

  7. Giant persistent photoconductivity in rough silicon nanomembranes.

    PubMed

    Feng, Ping; Mönch, Ingolf; Harazim, Stefan; Huang, Gaoshan; Mei, Yongfeng; Schmidt, Oliver G

    2009-10-01

    This paper reports the observation of giant persistent photoconductivity from rough Si nanomembranes. When exposed to light, the current in p-type Si nanomembranes is enhanced by roughly 3 orders of magnitude in comparison with that in the dark and can persist for days at a high conductive state after the light is switched off. An applied gate voltage can tune the persistent photocurrent and accelerate the response to light. By analyzing the band structure of the devices and the surfaces through various coatings, we attribute the observed effect to hole-localized regions in Si nanomembranes due to the rough surfaces, where light can activate the confined holes. PMID:19637888

  8. Foundations of chaotic mixing.

    PubMed

    Wiggins, Stephen; Ottino, Julio M

    2004-05-15

    The simplest mixing problem corresponds to the mixing of a fluid with itself; this case provides a foundation on which the subject rests. The objective here is to study mixing independently of the mechanisms used to create the motion and review elements of theory focusing mostly on mathematical foundations and minimal models. The flows under consideration will be of two types: two-dimensional (2D) 'blinking flows', or three-dimensional (3D) duct flows. Given that mixing in continuous 3D duct flows depends critically on cross-sectional mixing, and that many microfluidic applications involve continuous flows, we focus on the essential aspects of mixing in 2D flows, as they provide a foundation from which to base our understanding of more complex cases. The baker's transformation is taken as the centrepiece for describing the dynamical systems framework. In particular, a hierarchy of characterizations of mixing exist, Bernoulli --> mixing --> ergodic, ordered according to the quality of mixing (the strongest first). Most importantly for the design process, we show how the so-called linked twist maps function as a minimal picture of mixing, provide a mathematical structure for understanding the type of 2D flows that arise in many micromixers already built, and give conditions guaranteeing the best quality mixing. Extensions of these concepts lead to first-principle-based designs without resorting to lengthy computations. PMID:15306478

  9. Exploring the beliefs of persisting secondary science teachers in general induction programs: A longitudinal study

    NASA Astrophysics Data System (ADS)

    Wong, Sissy Sze-Mun

    Experienced, prepared, and fully certified teachers have been related with higher student achievement, but teacher retention has been a challenge for many decades, especially retention of secondary science teachers. In order to support teachers and student learning, it is critical to understand what impacts secondary science teachers' decisions to persist in the field. This mixed methods study explored whether teacher beliefs were related to persistence over a three-year period. Participants were beginning secondary science teachers that participated in general induction programs provided by their school or district. These participants were selected due to their representative nature of the average beginning secondary science teacher in the United States. Participants' responses to annual semi-structured interviews were the source of data. Findings from quantitative and qualitative analyses revealed that the persisting teachers' beliefs remained stable over the three-year period. Quantitative analyses also revealed that there were no prevalent beliefs among the persisting teachers, even when the variables of gender and socioeconomic status of their schools were considered. When persisting teachers' beliefs about teaching and beliefs about learning were quantitatively analyzed, no relationship was found. Case study of one persisting teacher and one non-persisting teacher revealed that personal experiences and knowledge impacted their beliefs about teaching and learning. The persisting teacher that participated in inquiry-based experiences held student-centered beliefs, while the non-persisting teacher that participated in verification-type experiences held teacher-centered beliefs. This study contributes to the field of science education by examining science teacher persistence instead of attrition. It focused specifically on secondary science teachers while exploring their beliefs longitudinally. Implications from this study calls for teacher beliefs to be

  10. Mixing and compaction temperatures for Superpave mixes

    NASA Astrophysics Data System (ADS)

    Yildirim, Yetkin

    According to Superpave mixture design, gyratory specimens are mixed and compacted at equiviscous binder temperatures corresponding to viscosities of 0.17 and 0.28 Pa.s. respectively. These were the values previously used in the Marshal mix design method to determine optimal mixing and compaction temperatures. In order to estimate the appropriate mixing and compaction temperatures for Superpave mixture design, a temperature-viscosity relationship for the binder needs to be developed (ASTM D 2493, Calculation of Mixing and Compaction Temperatures). The current approach is simple and provides reasonable temperatures for unmodified binders. However, some modified binders have exhibited unreasonably high temperatures for mixing and compaction using this technique. These high temperatures can result in construction problems, damage of asphalt, and production of fumes. Heating asphalt binder to very high temperatures during construction oxidizes the binder and separates the polymer from asphalt binder. It is known that polymer modified asphalt binders have many benefits to the roads, such as; increasing rutting resistance, enhancing low temperature cracking resistance, improving traction, better adhesion and cohesion, elevating tensile strength which are directly related to the service life of the pavement. Therefore, oxidation and separation of the polymer from the asphalt binder results in reduction of the service life. ASTM D 2493 was established for unmodified asphalt binders which are Newtonian fluids at high temperatures. For these materials, viscosity does not depend on shear rate. However, most of the modified asphalt binders exhibit a phenomenon known as pseudoplasticity, where viscosity does depend on shear rate. Thus, at the high shear rates occurring during mixing and compaction, it is not necessary to go to very high temperatures. This research was undertaken to determine the shear rate during compaction such that the effect of this parameter could be

  11. Helicobacter and Salmonella Persistent Infection Strategies

    PubMed Central

    Monack, Denise M.

    2013-01-01

    Some host-adapted bacterial pathogens are capable of causing persistent infections in humans. For example, Helicobacter pylori inhabits the human gastric mucosa and persistence can be lifelong. Salmonella enterica serovar Typhi causes systemic infections that involve colonization of the reticuloendothelial system and some individuals become lifelong carriers. In this review, I compare and contrast the different lifestyles of Helicobacter and Salmonella within the host and the strategies they have evolved to persist in mammalian hosts. Persistently infected carriers serve as the reservoirs for these pathogens, and the carrier state is an essential feature that is required for survival of the bacteria within a restricted host population. Therefore, investigating the chronic carrier state should provide insight into bacterial survival strategies, as well as new therapeutic approaches for treatments. PMID:24296347

  12. Persisters-as elusive as ever.

    PubMed

    Kaldalu, Niilo; Hauryliuk, Vasili; Tenson, Tanel

    2016-08-01

    Persisters-a drug-tolerant sub-population in an isogenic bacterial culture-have been featured throughout the last decade due to their important role in recurrent bacterial infections. Numerous investigations detail the mechanisms responsible for the formation of persisters and suggest exciting strategies for their eradication. In this review, we argue that the very term "persistence" is currently used to describe a large and heterogeneous set of physiological phenomena that are functions of bacterial species, strains, growth conditions, and antibiotics used in the experiments. We caution against the oversimplification of the mechanisms of persistence and urge for a more rigorous validation of the applicability of these mechanisms in each case. PMID:27262568

  13. Teen Birth Rates Drop, But Disparities Persist

    MedlinePlus

    ... Features Teen Birth Rates Drop, But Disparities Persist Language: English Español (Spanish) Recommend on Facebook Tweet Share Compartir The feature you selected is no longer available. In 10 seconds you will be automatically redirected to the CDC. ...

  14. The persistent stereotype: children's images of scientists

    NASA Astrophysics Data System (ADS)

    Emens McAdam, Janice

    1990-03-01

    Through their reading children learn to regard scientists as eccentrics. It is shown that this stereotype has persisted for over thirty years and affects many adult attitudes. Some methods of breaking the author-reader cycle are suggested.

  15. Stimuli, Reinforcers, and the Persistence of Behavior

    ERIC Educational Resources Information Center

    Nevin, John A.

    2009-01-01

    This article reviews evidence from basic and translational research with pigeons and humans suggesting that the persistence of operant behavior depends on the contingency between stimuli and reinforcers, and considers some implications for clinical interventions. (Contains 4 figures.)

  16. Persistence of the Lower Stratospheric Polar Vortices

    NASA Technical Reports Server (NTRS)

    Waugh, Darryn W.; Randel, William J.; Pawson, Steven; Newman, Paul A.; Nash, Eric R.

    1999-01-01

    The persistence of the Arctic and Antarctic lower stratospheric vortices is examined over the period 1958 to 1998. Three different vortex-following diagnostics (two using potential vorticity and one based solely on the zonal winds) are compared, and shown to give very similar results for the break up date. The variability in the timing of the breakup of each vortex is qualitatively the same: there are large interannual variations together with smaller decadal-scale variations and there is a significant increase in the persistence since the mid-1980s (all variations are larger for the Arctic vortex). Also, in both hemispheres there is a high correlation between the persistence and the strength and coldness of the spring vortex, with all quantities having the same interannual and decadal variability. However, there is no such correlation between the persistence and the characteristics of the mid-winter vortex. In the northern hemisphere there is also a high correlation between the vortex persistence and the upper tropospheric/lower stratospheric eddy heat flux averaged over the two months prior to the breakup. This indicates that the variability in the wave activity entering the stratosphere over late-winter to early-spring plays a key role in the variability of the vortex persistence (and spring polar temperatures) on both interannual and decadal time scales. However, the decadal variation in the Arctic vortex coldness and persistence for the 1990's falls outside the range of natural variability, while this is not the case for the eddy heat flux. This suggests that the recent increase in vortex persistence is not due solely to changes in the wave activity entering the stratosphere.

  17. Demystifying the persistent pneumothorax: role of imaging.

    PubMed

    Chaturvedi, Apeksha; Lee, Steven; Klionsky, Nina; Chaturvedi, Abhishek

    2016-06-01

    Evaluation for pneumothorax is an important indication for obtaining chest radiographs in patients who have had trauma, recent cardiothoracic surgery or are on ventilator support. By definition, a persistent pneumothorax constitutes ongoing bubbling of air from an in situ chest drain, 48 h after its insertion. Persistent pneumothorax remains a diagnostic dilemma and identification of potentially treatable aetiologies is important. These may be chest tube related (kinks or malposition), lung parenchymal disease, bronchopleural fistula, or rarely, oesophageal-pleural fistula. Although radiographs remain the mainstay for diagnosis and follow up of pneumothorax, computed tomography (CT) is increasingly being used for problem solving. Aetiology of persistent air leak determines the optimal treatment. For some, a simple repositioning of the chest tube/drain may suffice; others may require surgery. In this pictorial review, we will briefly describe the physiology of pneumothorax, discuss imaging features of identifiable causes for persistent pneumothorax and provide a brief overview of treatment options. Specific aetiology of a persistent air leak may often not be immediately discernible, and will need to be carefully sought. Accurate interpretation of imaging studies can expedite diagnosis and facilitate prompt treatment. Key points • Persistent pneumothorax is defined as a leak persisting for more than 2 days.• Radiographs can identify chest-tube-related causes of pneumothorax.• CT is the most useful test to identify other causes.• Penetrating thoracic injury can cause fistulous communication resulting in a persistent pneumothorax.• Discontinuity of visceral pleura identified by CT may indicate a bronchopleural fistula. PMID:27100907

  18. Persistent and Recurrent Clostridium difficile Colitis

    PubMed Central

    Cole, Shola A.; Stahl, Thomas J.

    2015-01-01

    Clostridium difficile infection (CDI) is the most frequent cause of nosocomial diarrhea. It has become a significant dilemma in the treatment of patients, and causes increasing morbidity that, in extreme cases, may result in death. Persistent and recurrent disease hamper attempts at eradication of this infection. Escalating levels of treatment and novel therapeutics are being utilized and developed to treat CDI. Further trials are warranted to definitively determine what protocols can be used to treat persistent and recurrent disease. PMID:26034401

  19. Persistent homology analysis of phase transitions

    NASA Astrophysics Data System (ADS)

    Donato, Irene; Gori, Matteo; Pettini, Marco; Petri, Giovanni; De Nigris, Sarah; Franzosi, Roberto; Vaccarino, Francesco

    2016-05-01

    Persistent homology analysis, a recently developed computational method in algebraic topology, is applied to the study of the phase transitions undergone by the so-called mean-field XY model and by the ϕ4 lattice model, respectively. For both models the relationship between phase transitions and the topological properties of certain submanifolds of configuration space are exactly known. It turns out that these a priori known facts are clearly retrieved by persistent homology analysis of dynamically sampled submanifolds of configuration space.

  20. Longitudinal persistence with secondary prevention therapies relative to patient risk after myocardial infarction

    PubMed Central

    Shore, Supriya; Jones, Philip G.; Maddox, Thomas M.; Bradley, Steven M.; Stolker, Joshua M.; Arnold, Suzanne V.; Parashar, Susmita; Peterson, Pamela; Bhatt, Deepak L.; Spertus, John; Ho, P. Michael

    2016-01-01

    Background Prior studies have demonstrated that high-risk AMI patients are less likely to receive guideline-directed medications during hospitalization. It is unknown if this paradox persists following discharge. We aimed to assess if persistence with guideline-directed medications post-discharge varies by patients’ risk following acute myocardial infarction (AMI). Methods Data were analyzed from two prospective, multicenter U.S. AMI registries. The primary outcome was persistence with all prescribed guideline-directed medications (aspirin, beta-blockers, statins, angiotensin-antagonists) at 1, 6, and 12-months post-discharge. The association between risk and medication persistence post-discharge was assessed using multivariable mixed-effect models. Results Among 6434 AMI patients discharged home, 2824 were considered low-risk, 2014 intermediate-risk and 1596 high-risk for death based upon their GRACE 6-month risk score. High-risk was associated with a lower likelihood of receiving all appropriate therapies at discharge compared with low-risk patients (RR 0.90; 95% CI 0.87–0.94). At 12-months, the rate of persistence with all prescribed therapies was 61.5%, 57.9% and 45.9% among low-, intermediate- and high-risk patients respectively. After multivariable adjustment, high-risk was associated with lower persistence with all prescribed medications (RR 0.87; 95% CI 0.82–0.92) over follow-up. Similar associations were seen for individual medications. Over the 5 years of the study, persistence with prescribed therapies post-discharge improved modestly among high-risk patients (RR 1.05; 95% CI 1.03–1.08 per year). Conclusion High-risk AMI patients have a lower likelihood of persistently taking prescribed medications post-discharge as compared with low-risk patients. Continued efforts are needed to improve the use of guideline-directed medications in high-risk patients. PMID:25801001

  1. Persistent multitiered magma plumbing beneath Katla volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Budd, David A.; Troll, Valentin R.; Dahren, Börje; Burchardt, Steffi

    2016-03-01

    Recent seismic unrest and a persistent Holocene eruption record at Katla volcano, Iceland indicate that a near-future eruption is possible. Previous petrological investigations suggest that Katla is supplied by a simple plumbing system that delivers magma directly from depth, while seismic and geodetic data also point toward the existence of upper-crustal magma storage. To characterize Katla's recent plumbing system, we established mineral-melt equilibrium crystallization pressures from four age-constrained Katla tephras spanning from 8 kyr BP to 1918. The results point to persistent shallow- (≤8 km depth) as well as deep-crustal (ca. 10 - 25 km depth) magma storage beneath Katla throughout the last 8 kyr. The presence of multiple magma storage regions implies that mafic magma from the deeper reservoir system may become gas-rich during ascent and storage in the shallow crust and erupt explosively. Alternatively, it might intersect evolved magma pockets in the shallow-level storage region, and so increase the potential for explosive mixed-magma ash eruptions.

  2. Persistence of Pigment Production by Yeast Isolates Grown on CHROMagar Candida Medium

    PubMed Central

    Hospenthal, Duane R.; Murray, Clinton K.; Beckius, Miriam L.; Green, Judith A.; Dooley, David P.

    2002-01-01

    We evaluated the persistence of pigmentation in yeast isolates grown on the chromogenic medium CHROMagar Candida over 7 days. Candida, Cryptococcus, and Trichosporon isolates were inoculated alone or mixed onto duplicate sets of plates and incubated at 30 and 35°C. Candida albicans and Candida krusei were readily identified throughout the reading period, but Candida glabrata was difficult to differentiate from other species until the 3- or 4-day time point. Candida tropicalis produced colonies similar to those of rare Cryptococcus and Trichosporon species, and mixed cultures were often difficult to identify as such. PMID:12454192

  3. PERSISTENT BREAST PAIN FOLLOWING BREAST CANCER SURGERY IS ASSOCIATED WITH PERSISTENT SENSORY CHANGES, PAIN INTERFERENCE, AND FUNCTIONAL IMPAIRMENTS

    PubMed Central

    Langford, Dale J.; Paul, Steven M.; West, Claudia; Levine, Jon D.; Hamolsky, Deborah; Elboim, Charles; Schmidt, Brian L.; Cooper, Bruce A.; Abrams, Gary; Aouizerat, Bradley E.; Miaskowski, Christine

    2014-01-01

    Inter-individual variability exists in persistent breast pain following breast cancer surgery. Recently, we used growth mixture modeling to identify three subgroups of women (n=398) with distinct persistent breast pain trajectories over six months following surgery (i.e., Mild, Moderate, Severe). Purposes of this study were to identify demographic and clinical characteristics that differed among the breast pain classes and, using linear mixed effects modeling, determine how changes over time, in sensitivity in the breast scar area, pain qualities, pain interference, and hand and arm function differed among these classes. Several demographic and clinical characteristics differentiated the breast pain classes. Of note, 60% to 80% of breast scar sites tested were much less sensitive than the unaffected breast. Significant group effects were observed for pain qualities and interference scores, such that, on average, women in the Severe Pain class reported higher scores than women in the Moderate Pain class. In addition, women in the Moderate Pain class reported higher scores than women in the Mild Pain class. Compared to the Mild Pain class, women in the Severe Pain class had significantly impaired grip strength and women in the Moderate and Severe Pain classes had impaired flexion and abduction. PMID:25439318

  4. Herbicide Persistence in Seawater Simulation Experiments

    PubMed Central

    Mercurio, Philip; Mueller, Jochen F.; Eaglesham, Geoff; Flores, Florita; Negri, Andrew P.

    2015-01-01

    Herbicides are detected year-round in marine waters, including those of the World Heritage listed Great Barrier Reef (GBR). The few previous studies that have investigated herbicide persistence in seawater generally reported half-lives in the order of months, and several studies were too short to detect significant degradation. Here we investigated the persistence of eight herbicides commonly detected in the GBR or its catchments in standard OECD simulation flask experiments, but with the aim to mimic natural conditions similar to those found on the GBR (i.e., relatively low herbicide concentrations, typical temperatures, light and microbial communities). Very little degradation was recorded over the standard 60 d period (Experiment 1) so a second experiment was extended to 365 d. Half-lives of PSII herbicides ametryn, atrazine, diuron, hexazinone and tebuthiuron were consistently greater than a year, indicating high persistence. The detection of atrazine and diuron metabolites and longer persistence in mercuric chloride-treated seawater confirmed that biodegradation contributed to the breakdown of herbicides. The shortest half-life recorded was 88 d for growth-regulating herbicide 2,4-D at 31°C in the dark, while the fatty acid-inhibitor metolachlor exhibited a minimum half-life of 281 d. The presence of moderate light and elevated temperatures affected the persistence of most of the herbicides; however, the scale and direction of the differences were not predictable and were likely due to changes in microbial community composition. The persistence estimates here represent some of the first appropriate data for application in risk assessments for herbicide exposure in tropical marine systems. The long persistence of herbicides identified in the present study helps explain detection of herbicides in nearshore waters of the GBR year round. Little degradation of these herbicides would be expected during the wet season with runoff and associated flood plumes

  5. Herbicide Persistence in Seawater Simulation Experiments.

    PubMed

    Mercurio, Philip; Mueller, Jochen F; Eaglesham, Geoff; Flores, Florita; Negri, Andrew P

    2015-01-01

    Herbicides are detected year-round in marine waters, including those of the World Heritage listed Great Barrier Reef (GBR). The few previous studies that have investigated herbicide persistence in seawater generally reported half-lives in the order of months, and several studies were too short to detect significant degradation. Here we investigated the persistence of eight herbicides commonly detected in the GBR or its catchments in standard OECD simulation flask experiments, but with the aim to mimic natural conditions similar to those found on the GBR (i.e., relatively low herbicide concentrations, typical temperatures, light and microbial communities). Very little degradation was recorded over the standard 60 d period (Experiment 1) so a second experiment was extended to 365 d. Half-lives of PSII herbicides ametryn, atrazine, diuron, hexazinone and tebuthiuron were consistently greater than a year, indicating high persistence. The detection of atrazine and diuron metabolites and longer persistence in mercuric chloride-treated seawater confirmed that biodegradation contributed to the breakdown of herbicides. The shortest half-life recorded was 88 d for growth-regulating herbicide 2,4-D at 31°C in the dark, while the fatty acid-inhibitor metolachlor exhibited a minimum half-life of 281 d. The presence of moderate light and elevated temperatures affected the persistence of most of the herbicides; however, the scale and direction of the differences were not predictable and were likely due to changes in microbial community composition. The persistence estimates here represent some of the first appropriate data for application in risk assessments for herbicide exposure in tropical marine systems. The long persistence of herbicides identified in the present study helps explain detection of herbicides in nearshore waters of the GBR year round. Little degradation of these herbicides would be expected during the wet season with runoff and associated flood plumes

  6. Characterization of Bacillus anthracis Persistence In Vivo

    PubMed Central

    Jenkins, Sarah A.; Xu, Yi

    2013-01-01

    Pulmonary exposure to Bacillus anthracis spores initiates inhalational anthrax, a life-threatening infection. It is known that dormant spores can be recovered from the lungs of infected animals months after the initial spore exposure. Consequently, a 60-day course antibiotic treatment is recommended for exposed individuals. However, there has been little information regarding details or mechanisms of spore persistence in vivo. In this study, we investigated spore persistence in a mouse model. The results indicated that weeks after intranasal inoculation with B. anthracis spores, substantial amounts of spores could be recovered from the mouse lung. Moreover, spores of B. anthracis were significantly better at persisting in the lung than spores of a non-pathogenic Bacillus subtilis strain. The majority of B. anthracis spores in the lung were tightly associated with the lung tissue, as they could not be readily removed by lavage. Immunofluorescence staining of lung sections showed that spores associated with the alveolar and airway epithelium. Confocal analysis indicated that some of the spores were inside epithelial cells. This was further confirmed by differential immunofluorescence staining of lung cells harvested from the infected lungs, suggesting that association with lung epithelial cells may provide an advantage to spore persistence in the lung. There was no or very mild inflammation in the infected lungs. Furthermore, spores were present in the lung tissue as single spores rather than in clusters. We also showed that the anthrax toxins did not play a role in persistence. Together, the results suggest that B. anthracis spores have special properties that promote their persistence in the lung, and that there may be multiple mechanisms contributing to spore persistence. PMID:23750280

  7. Mixed oxide solid solutions

    DOEpatents

    Magno, Scott; Wang, Ruiping; Derouane, Eric

    2003-01-01

    The present invention is a mixed oxide solid solution containing a tetravalent and a pentavalent cation that can be used as a support for a metal combustion catalyst. The invention is furthermore a combustion catalyst containing the mixed oxide solid solution and a method of making the mixed oxide solid solution. The tetravalent cation is zirconium(+4), hafnium(+4) or thorium(+4). In one embodiment, the pentavalent cation is tantalum(+5), niobium(+5) or bismuth(+5). Mixed oxide solid solutions of the present invention exhibit enhanced thermal stability, maintaining relatively high surface areas at high temperatures in the presence of water vapor.

  8. An Exploration of Academically Underprepared Students' Decisions to Persist at a Large Urban Community College in California

    ERIC Educational Resources Information Center

    Kingori, Margaret

    2011-01-01

    The purpose of this study was to examine the factors that influence underprepared students' persistence at a California community college. A mixed method, sequential explanatory design comprised of a quantitative phase followed by a qualitative phase was utilized. The quantitative part entailed statistical analysis of data available through the…

  9. "A pesar de todo" (Despite Everything): The Persistence of Latina Graduate Engineering Students at a Hispanic-Serving Institution

    ERIC Educational Resources Information Center

    Aguirre-Covarrubias, Sandra; Arellano, Eduardo; Espinoza, Penelope

    2015-01-01

    This chapter discusses a mixed-methods study of personal and programmatic factors that affected persistence of Latina graduate engineering students at a Hispanic-serving institution (HSI). The study's findings enabled us to share recommendations that may be useful to HSIs and other colleges and universities.

  10. Persistent agents in Axelrod's social dynamics model

    NASA Astrophysics Data System (ADS)

    Reia, Sandro M.; Neves, Ubiraci P. C.

    2016-01-01

    Axelrod's model of social dynamics has been studied under the effect of external media. Here we study the formation of cultural domains in the model by introducing persistent agents. These are agents whose cultural traits are not allowed to change but may be spread through local neighborhood. In the absence of persistent agents, the system is known to present a transition from a monocultural to a multicultural regime at some critical Q (number of traits). Our results reveal a dependence of critical Q on the occupation probability p of persistent agents and we obtain the phase diagram of the model in the (p,Q) -plane. The critical locus is explained by the competition of two opposite forces named here barrier and bonding effects. Such forces are verified to be caused by non-persistent agents which adhere (adherent agents) to the set of traits of persistent ones. The adherence (concentration of adherent agents) as a function of p is found to decay for constant Q. Furthermore, adherence as a function of Q is found to decay as a power law with constant p.

  11. Persistent Scatterer Interferometry Using SENTINEL-1 Data

    NASA Astrophysics Data System (ADS)

    Crosetto, M.; Monserrat, O.; Devanthéry, N.; Cuevas-González, M.; Barra, A.; Crippa, B.

    2016-06-01

    This paper is focused on deformation monitoring using a Persistent Scatterer Interferometry technique and the interferometric SAR data acquired by the Sentinel-1 satellite of the European Space Agency. The first part of the paper describes the procedure used to process and analyze Sentinel-1 interferometric SAR data. Two main approaches are described. The first one is a simplified Persistent Scatterer Interferometry approach that exploits two key properties of the Sentinel-1 data: the high coherence of the 12-day interferograms and the reduced orbital tube. The second approach is a full Persistent Scatterer Interferometry approach, where a more sophisticate data treatment is employed. The second part of the paper illustrates the results obtained with the two processing approaches. Two case studies are described. The first one concerns landslide detection and monitoring. In this case, the simplified Persistent Scatterer Interferometry approach was used. The second one regards the deformation monitoring of an urban area. In this case, a full Persistent Scatterer Interferometry approach was used.

  12. Dry season streamflow persistence in seasonal climates

    NASA Astrophysics Data System (ADS)

    Dralle, David N.; Karst, Nathaniel J.; Thompson, Sally E.

    2016-01-01

    Seasonally dry ecosystems exhibit periods of high water availability followed by extended intervals during which rainfall is negligible and streamflows decline. Eventually, such declining flows will fall below the minimum values required to support ecosystem functions or services. The time at which dry season flows drop below these minimum values (Q*), relative to the start of the dry season, is termed the "persistence time" (). The persistence time determines how long seasonal streams can support various human or ecological functions during the dry season. In this study, we extended recent work in the stochastic hydrology of seasonally dry climates to develop an analytical model for the probability distribution function (PDF) of the persistence time. The proposed model accurately captures the mean of the persistence time distribution, but underestimates its variance. We demonstrate that this underestimation arises in part due to correlation between the parameters used to describe the dry season recession, but that this correlation can be removed by rescaling the flow variables. The mean persistence time predictions form one example of the broader class of streamflow statistics known as crossing properties, which could feasibly be combined with simple ecological models to form a basis for rapid risk assessment under different climate or management scenarios.

  13. On persistence interfaces for scientific data stores

    SciTech Connect

    Malon, D.M.; May, E.N.

    1996-02-09

    A common dilemma among builders of large scientific data stores is whether to use a lightweight object persistence manager or a genuine object-oriented database. There are often good reasons to consider each of these strategies; a few are described in this paper. Too often, however, electing to use a lightweight approach has meant programming to an interface that is entirely different than that expected by commercial object-oriented databases. With the emergence of object database standards, it is possible to provide an interface to persistence managers that does not needlessly inhibit coexistence with (and, perhaps, eventual migration to) object-oriented databases. This paper describes an implementation of a substantial subset of the ODMG-93[1]C++ specification that allows clients to use many of today`s lightweight object persistence managers through an interface that conforms to the ODMG standard. We also describe a minimal interface that persistence software should support in order to provide persistence services for ODMG implementations.

  14. Persistent Pain and Sensory Abnormalities after Abdominoplasty

    PubMed Central

    Finnerup, Kenneth; Andresen, Sven R.; Nikolajsen, Lone; Finnerup, Nanna B.

    2015-01-01

    Background: Persistent postsurgical pain is a well-recognized problem after a number of common surgical procedures, such as amputation, thoracotomy, and inguinal hernia repair. Less is known about persistent pain after cosmetic surgical procedures. We, therefore, decided to study the incidence and characteristics of persistent pain after abdominoplasty, which is one of the most frequent cosmetic surgical procedures. Methods: In September 2014, a link to a web-based questionnaire was mailed to 217 patients who had undergone abdominoplasty between 2006 and 2014 at the Department of Plastic Surgery, Aalborg University Hospital, Denmark. The questionnaire included questions about pain and sensory abnormalities located to the abdominal skin, and physical and psychological function; patient satisfaction with surgery was rated on a 4-point scale. Results: One hundred seventy patients answered the questionnaire. Fourteen patients (8.2%) reported pain within the past 7 days related to the abdominoplasty. Abnormal abdominal skin sensation was common and reported by 138 patients (81%). Sensory hypersensitivity was associated with the presence of persistent pain. Satisfaction with the procedure was reported by 149 (88%) patients. The majority of patients reported improvement on all physical and psychological factors. Patients with pain were more often disappointed with the surgery and unwilling to recommend the surgery. Conclusions: Overall, patients were satisfied with the procedure, although abnormal abdominal skin sensation was common. However, there is a risk of developing persistent neuropathic pain after abdominoplasty, and patients should be informed about this before surgery. PMID:26893986

  15. Hepatitis C virus as a systemic disease: reaching beyond the liver.

    PubMed

    Gill, Kirat; Ghazinian, Hasmik; Manch, Richard; Gish, Robert

    2016-05-01

    Chronic hepatitis C (CHC) is associated with multiple extrahepatic manifestations that may impact infected patients. The mechanisms through which these develop include those which are immunological, in which the chronic persistence of virus leads to the circulation of immune complexes (mixed cryoglobulinemia) and other autoimmune phenomena, and those which are virological and related to the extrahepatic tropism of the virus to other tissues. It is estimated that 40-74 % of patients with CHC may develop at least one extrahepatic manifestation during the course of the disease. Extrahepatic syndromes may represent the first signal of hepatitis C infection in some patients. CHC is associated with a four-fold increased risk of insulin resistance and type 2 diabetes mellitus; with cardiovascular disease in 17-37 % of patients; and with increased risk for cerebrovascular deaths, with a biological gradient of cerebrovascular mortality correlating with an increasing serum viral load. CHC is also associated with lymphoproliferative disorders, particularly non-Hodgkin B-cell lymphoma. The kidney is involved in 35-60 % of patients with CHC-associated mixed cryoglobulinemia. The prevalent type of glomerulonephritis associated with mixed cryoglobulinemia is membranoproliferative glomerulonephritis. In 30 % of cases, renal involvement begins with a nephritis syndrome and acute renal failure, while in 55 % there is only mild hematuria, microalbuminuria, proteinuria and renal insufficiency. CHC is also associated with cognitive impairment, especially in memory and concentration. Thus, extrahepatic CHC manifestations involve multiple organ systems outside the liver linked to a variety of comorbidities which may lead to significantly increased mortality from non-liver-related events. PMID:26660706

  16. Mixing and scaling of accelerated interfaces

    NASA Astrophysics Data System (ADS)

    Garzon, A.; Rozanov, V.; Redondo, J. M.

    2009-04-01

    Rayleigh-Taylor (RT) instability occurs when a layer of dense fluid is placed on top of a less dense layer in a gravitational field or are accelerated. The instability forms a turbulent front between the two layers, but some patterns seem to have a persistent memory of the initial conditions as turbulence develops. The advance of this front is described in Linden & Redondo (1991), and may be shown to follow a quadratic law in time. The width of the growing region of instability is proportional to the Atwood number but the distribution of fractal interfaces between the miscible fluids allow to distinguish the dominant mixing regions located at the sides of the RT blobs, where accelerated shear is greatest. A Large Eddy Simulation numerical model is used to predict some of the features of the experiments, different models on the interaction of the bubble generated buoyancy flux and on the boundary conditions are compared with the experiments. The aspect ratios of the bubble induced convective cells and some mixing descriptors are also seen to depend on the boundary conditions applied to the enclosure. The influence of the initial conditions on the structure of the flow and its mixing ability are investigated by means of image analysis, PIV and scaling analysis to determine the regions of the front which contribute most to molecular mixing.

  17. The Childrens Total Exposure to Persistent Pesticides and Other Persistent Organic Pollutants (CTEPP) Study

    EPA Science Inventory

    The Children's Total Exposure to Persistent Pesticides and Other Persistent Pollutant (CTEPP) study was one of the largest aggregate exposure studies of young children in the United States. The CTEPP study examined the exposures of about 260 preschool children and their primary a...

  18. The Childrens Total Exposure to Persistent Pesticides and Other Persistent Organic Pollutants (CTEPP) Study -- Ohio

    EPA Science Inventory

    The Children's Total Exposure to Persistent Pesticides and Other Persistent Pollutant (CTEPP) study was one of the largest aggregate exposure studies of young children in the United States. The CTEPP study examined the exposures of about 260 preschool children and their primary a...

  19. THE CHILDRENS TOTAL EXPOSURE TO PERSISTENT PESTICIDES AND OTHER PERSISTENT ORGANIC POLLUTANTS (CTEPP) STUDY -- NORTH CAROLINA

    EPA Science Inventory

    The Children's Total Exposure to Persistent Pesticides and Other Persistent Pollutant (CTEPP) study was one of the largest aggregate exposure studies of young children in the United States. The CTEPP study examined the exposures of about 260 preschool children and their primary a...

  20. Persistence of community college engineering science students: The impact of selected cognitive and noncognitive characteristics

    NASA Astrophysics Data System (ADS)

    Chatman, Lawrence M., Jr.

    If the United States is to remain technologically competitive, persistence in engineering programs must improve. This study on student persistence employed a mixed-method design to identify the cognitive and noncognitive factors which contribute to students remaining in an engineering science curriculum or switching from an engineering curriculum at a community college in the northeast United States. Records from 372 students were evaluated to determine the characteristics of two groups: those students that persisted with the engineering curriculum and those that switched from engineering; also, the dropout phenomenon was evaluated. The quantitative portion of the study used a logistic regression analyses on 22 independent variables, while the qualitative portion of the study used group interviews to investigate the noncognitive factors that influenced persisting or switching. The qualitative portion of the study added depth and credibility to the results from the quantitative portion. The study revealed that (1) high grades in first year calculus, physics and chemistry courses, (2) fewer number of semesters enrolled, (3) attendance with full time status, and (4) not participating in an English as a Second Language (ESL) program were significant variables used to predict student persistence. The group interviews confirmed several of these contributing factors. Students that dropped out of college began with (1) the lowest levels of remediation, (2) the lowest grade point averages, and (3) the fewest credits earned.

  1. Persistence and predictability in a perfect model

    NASA Technical Reports Server (NTRS)

    Schubert, Siegfried D.; Suarez, Max J.; Schemm, Jae-Kyung

    1992-01-01

    A realistic two-level GCM is used to examine the relationship between predictability and persistence. Predictability is measured by the average divergence of ensembles of solutions starting from perturbed initial conditions, and persistence is defined in terms of the autocorrelation function based on a single long-term model integration. The average skill of the dynamical forecasts is compared with the skill of simple persistence-based statistical forecasts. For initial errors comparable in magnitude to present-day analysis errors, the statistical forecast loses all skill after about one week, reflecting the lifetime of the lowest frequency fluctuations in the model. Large ensemble mean dynamical forecasts would be expected to remain skillful for about 3 wk. The disparity between the skill of the statistical and dynamical forecasts is greater for the higher frequency modes, which have little memory beyond 1 d, yet remain predictable for about 2 wk. The results are analyzed in terms of two characteristic time scales.

  2. Contrasting persistence strategies in Salmonella and Mycobacterium

    PubMed Central

    McKinney, John D.

    2009-01-01

    Summary Long-term survival of persistent bacterial pathogens in mammalian hosts critically depends on their ability to avoid elimination by innate and adaptive immune responses. The persistent human pathogens that cause typhoid fever and tuberculosis exemplify alternative strategies for survival in the host: immune evasion and immune adaptation, respectively. Salmonella enterica serotype Typhi evades host innate immune responses and inflammation by expressing factors that interfere with its detection as a Gram-negative bacterium, enabling persistent colonization of an immunologically privileged niche, the gallbladder. In contrast, Mycobacterium tuberculosis has adapted to survive within phagocytic cells, which typically eliminate invading microbes, by deploying stress resistance mechanisms that counteract the harsh environment of the phagolysosome. PMID:20056478

  3. Persistent Structures in the Turbulent Boundary Layer

    NASA Technical Reports Server (NTRS)

    Palumbo, Dan; Chabalko, Chris

    2005-01-01

    Persistent structures in the turbulent boundary layer are located and analyzed. The data are taken from flight experiments on large commercial aircraft. An interval correlation technique is introduced which is able to locate the structures. The Morlet continuous wavelet is shown to not only locates persistent structures but has the added benefit that the pressure data are decomposed in time and frequency. To better understand how power is apportioned among these structures, a discrete Coiflet wavelet is used to decompose the pressure data into orthogonal frequency bands. Results indicate that some structures persist a great deal longer in the TBL than would be expected. These structure contain significant power and may be a primary source of vibration energy in the airframe.

  4. Persistent hydrogen bonding in polymorphic crystal structures.

    PubMed

    Galek, Peter T A; Fábián, László; Allen, Frank H

    2009-02-01

    The significance of hydrogen bonding and its variability in polymorphic crystal structures is explored using new automated structural analysis methods. The concept of a chemically equivalent hydrogen bond is defined, which may be identified in pairs of structures, revealing those types of bonds that may persist, or not, in moving from one polymorphic form to another. Their frequency and nature are investigated in 882 polymorphic structures from the Cambridge Structural Database. A new method to compare conformations of equivalent molecules is introduced and applied to derive distinct subsets of conformational and packing polymorphs. The roles of chemical functionality and hydrogen-bond geometry in persistent interactions are systematically explored. Detailed structural comparisons reveal a large majority of persistent hydrogen bonds that are energetically crucial to structural stability. PMID:19155561

  5. Vegetation persistence and carbon storage: Implications for environmental water management for Phragmites australis

    NASA Astrophysics Data System (ADS)

    Whitaker, Kai; Rogers, Kerrylee; Saintilan, Neil; Mazumder, Debashish; Wen, Li; Morrison, R. J.

    2015-07-01

    Environmental water allocations are used to improve the ecological health of wetlands. There is now increasing demand for allocations to improve ecosystem productivity and respiration, and enhance carbon sequestration. Despite global recognition of wetlands as carbon sinks, information regarding carbon dynamics is lacking. This is the first study estimating carbon sequestration for semiarid Phragmites australis reedbeds. The study combined aboveground biomass assessments with stable isotope analyses of soils and modeling of biomass using Normalized Digital Vegetation Index (NDVI) to investigate the capacity of environmental water allocations to improve carbon storage. The study considered relationships between soil organic carbon (SOC), carbon sources, and reedbed persistence in the Macquarie Marshes, a regulated semiarid floodplain of the Murray-Darling Basin, Australia. SOC storage levels to 1 m soil depth were higher in persistent reedbeds (167 Mg ha-1) than ephemeral reedbeds (116-138 Mg ha-1). In situ P. australis was the predominant source of surface SOC at persistent reedbeds; mixed sources of surface SOC were proposed for ephemeral reedbeds. 13C enrichment with increasing soil depth occurred in persistent and ephemeral reedbeds and may not relate to flow characteristics. Despite high SOC at persistent reedbeds, differences in the rate of accretion contributed to significantly higher rates of carbon sequestration at ephemeral reedbeds (approximately 554 and 465 g m-2 yr-1) compared to persistent reedbeds (5.17 g m-2 yr-1). However, under current water regimes, rapid accretion at ephemeral reedbeds cannot be maintained. Effective management of persistent P. australis reedbeds may enhance carbon sequestration in the Macquarie Marshes and floodplain wetlands more generally.

  6. High-mix insulins

    PubMed Central

    Kalra, Sanjay; Farooqi, Mohammad Hamed; El-Houni, Ali E.

    2015-01-01

    Premix insulins are commonly used insulin preparations, which are available in varying ratios of different molecules. These drugs contain one short- or rapid-acting, and one intermediate- or long-acting insulin. High-mix insulins are mixtures of insulins that contain 50% or more than 50% of short-acting insulin. This review describes the clinical pharmacology of high-mix insulins, including data from randomized controlled trials. It suggests various ways, in which high-mix insulin can be used, including once daily, twice daily, thrice daily, hetero-mix, and reverse regimes. The authors provide a rational framework to help diabetes care professionals, identify indications for pragmatic high-mix use. PMID:26425485

  7. Theory for Neutrino Mixing

    NASA Astrophysics Data System (ADS)

    He, Xiao-Gang

    2016-07-01

    Since the discovery of neutrino oscillations, for which Takaaki Kajita and Arthur B. McDonald were awarded the 2015 Nobel prize in physics, tremendous progresses have been made in measuring the mixing angles which determine the oscillation pattern. A lot of theoretical efforts have been made to understand how neutrinos mix with each other. Present data show that in the standard parameterization of the mixing matrix, θ23 is close to π/4 and the CP violating phase is close to ‑ π/2. In this talk I report results obtained in arXiv:1505.01932 (Phys. Lett. B750(2015)620) and arXive:1404.01560 (Chin. J. Phys.53(2015)100101) and discuss some implications for theoretical model buildings for such mixing pattern. Specific examples for neutrino mixing based on A4 family symmetry are given.

  8. Microfluidic Mixing: A Review

    PubMed Central

    Lee, Chia-Yen; Chang, Chin-Lung; Wang, Yao-Nan; Fu, Lung-Ming

    2011-01-01

    The aim of microfluidic mixing is to achieve a thorough and rapid mixing of multiple samples in microscale devices. In such devices, sample mixing is essentially achieved by enhancing the diffusion effect between the different species flows. Broadly speaking, microfluidic mixing schemes can be categorized as either “active”, where an external energy force is applied to perturb the sample species, or “passive”, where the contact area and contact time of the species samples are increased through specially-designed microchannel configurations. Many mixers have been proposed to facilitate this task over the past 10 years. Accordingly, this paper commences by providing a high level overview of the field of microfluidic mixing devices before describing some of the more significant proposals for active and passive mixers. PMID:21686184

  9. Amnestically Induced Persistence in Random Walks

    NASA Astrophysics Data System (ADS)

    Cressoni, J. C.; da Silva, Marco Antonio Alves; Viswanathan, G. M.

    2007-02-01

    We study how the Hurst exponent α depends on the fraction f of the total time t remembered by non-Markovian random walkers that recall only the distant past. We find that otherwise nonpersistent random walkers switch to persistent behavior when inflicted with significant memory loss. Such memory losses induce the probability density function of the walker’s position to undergo a transition from Gaussian to non-Gaussian. We interpret these findings of persistence in terms of a breakdown of self-regulation mechanisms and discuss their possible relevance to some of the burdensome behavioral and psychological symptoms of Alzheimer’s disease and other dementias.

  10. Persistent migraine aura in an adolescent girl.

    PubMed

    Bruen, Robin; Peng, Si Liang; Perreault, Sebastien; Major, Philippe; Ospina, Luis H

    2013-08-01

    A 14-year-old girl presented with a prolonged migraine visual aura of several weeks' duration. Symptoms gradually resolved over a 6-week period, with no recurrence of visual aura over a 20-month follow-up period. Although there is significant overlap between the features of stereotypical and persistent migraine auras, or "visual snow," the latter tend to be unformed and can occupy the entire visual field of both eyes. To our knowledge, this phenomenon has been reported only twice before in children. Recognition of its features will allow the pediatric ophthalmologist to differentiate persistent visual aura from visual hallucinations. PMID:23871134

  11. Chronic Bacterial Pathogens: Mechanisms of Persistence

    PubMed Central

    Byndloss, Mariana X.; Tsolis, Renee M

    2015-01-01

    Summary Many bacterial pathogens can cause acute infections that are cleared with onset of adaptive immunity, however a subset of these pathogens can establish persistent, and sometimes lifelong infections. While bacteria causing chronic infections are phylogenetically diverse, they share common features in their interactions with the host that enable a protracted period of colonization. This chapter will compare the persistence strategies of two chronic pathogens from the Proteobacteria, Brucella abortus, and Salmonella enterica serovar Typhi (S. Typhi) to consider how these two pathogens, which are very different at the genomic level, can utilize common strategies to evade immune clearance to cause chronic intracellular infections of the mononuclear phagocyte system. PMID:27227304

  12. Trigeminal neuralgia and persistent trigeminal artery.

    PubMed

    Conforti, Renata; Parlato, Raffaele Stefano; De Paulis, Danilo; Cirillo, Mario; Marrone, Valeria; Cirillo, Sossio; Moraci, Aldo; Parlato, Ciro

    2012-12-01

    We report a case of trigeminal neuralgia caused by persistent trigeminal artery (PTA) associated with asymptomatic left temporal cavernoma. Our patient presented unstable blood hypertension and the pain of typical trigeminal neuralgia over the second and third divisions of the nerve in the right side of the face. The attacks were often precipitated during physical exertion. MRI and Angio-MRI revealed the persistent carotid basilar anastomosis and occasionally left parietal cavernoma. After drug treatment of blood hypertension, spontaneous recovery of neuralgia was observed and we planned surgical treatment of left temporal cavernoma. PMID:22246457

  13. Nicotine replacement therapies: patient safety and persistence

    PubMed Central

    Ferguson, Stuart G; Shiffman, Saul; Gitchell, Joseph G

    2011-01-01

    Nicotine replacement therapy (NRT) has become a central part of the treatment of nicotine dependence. However, NRT’s potential efficacy is limited to some extent by patient adherence and persistence. Here we review the relationship between NRT compliance and adherence, and overall treatment outcome. We then examine the factors that likely impact on treatment compliance and persistence, with a special focus on users’ perceptions of treatment safety and efficacy as possible mediators. Potential clinical strategies for improving suboptimal medication use are also discussed. PMID:22915971

  14. Infection persistence time of Aedes breeding habitats

    NASA Astrophysics Data System (ADS)

    Bicout, D. J.; Chalvet-Monfray, K.; Sabatier, P.

    2002-03-01

    The Aedes mosquito species are capable of maintaining the circulation of viruses only by the strategy of transovarial transmission and diapause of eggs. It is found that when the transovarial transmission is inhibited, the survival time of the presence of viruses in a given mosquito habitat is limited from above by the eggs lifetime. In contrast, when the transovarial transmission is turned on, the infection persistence time may largely exceed both the eggs lifetime and flooding period depending upon the production rate of infected eggs. We present a simple model allowing the derivation of analytical expressions of the infection persistence time.

  15. The dynamics of Persistent Cold-Air Pool breakup

    NASA Astrophysics Data System (ADS)

    Lareau, Neil P.

    The wind-induced disruption and breakup of multiday cold-air pools are investigated using observational analyses and idealized numerical simulations. The observations are from the Persistent Cold-Air Pool (CAP) Study, which provides modern measurement of the meteorological processes affecting the duration of cold-air pools in the Salt Lake Valley of Utah. In general, the observations indicate that synoptic-scale processes control cold-air pool duration while local processes affect near-surface stratification and mixing. The most common form of CAP breakup is due to cold-air advection aloft. However, analyses reveal that some cold-air pools are destroyed or disrupted by strong winds penetrating into the valley. The resulting wind-CAP interactions are complex, involving sequential CAP displacements, internal oscillations, dynamic instabilities, and terrain-flow interactions. Large Eddy Simulations of multiday cold-air pools in idealized valley topography further demonstrate that cold-air pool removal is affected by the interplay of Kelvin-Helmholtz instability and warm air advection. This dynamic instability generates breaking waves in the stratified shear flow that mix cold-air into the warmer flow aloft. Variations in the initial cold pool stratification and valley terrain affect the timescale for cold-air pool removal. Despite these variations, a basic relationship between the magnitude of the flow aloft and the strength of the underlying cold-air pool can be expressed in terms of the "CAP Froude number." This dimensionless quantity is useful for diagnosing the onset and amplification of turbulent mixing, as well as the complete removal of cold-air pools.

  16. ADVANCED MIXING MODELS

    SciTech Connect

    Lee, S; Dimenna, R; Tamburello, D

    2011-02-14

    The process of recovering and processing High Level Waste (HLW) the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank with one to four mixers (pumps) located within the tank. The typical criteria to establish a mixed condition in a tank are based on the number of pumps in operation and the time duration of operation. To ensure that a mixed condition is achieved, operating times are typically set conservatively long. This approach results in high operational costs because of the long mixing times and high maintenance and repair costs for the same reason. A significant reduction in both of these costs might be realized by reducing the required mixing time based on calculating a reliable indicator of mixing with a suitably validated computer code. The focus of the present work is to establish mixing criteria applicable to miscible fluids, with an ultimate goal of addressing waste processing in HLW tanks at SRS and quantifying the mixing time required to suspend sludge particles with the submersible jet pump. A single-phase computational fluid dynamics (CFD) approach was taken for the analysis of jet flow patterns with an emphasis on the velocity decay and the turbulent flow evolution for the farfield region from the pump. Literature results for a turbulent jet flow are reviewed, since the decay of the axial jet velocity and the evolution of the jet flow patterns are important phenomena affecting sludge suspension and mixing operations. The work described in this report suggests a basis for further development of the theory leading to the identified mixing indicators, with benchmark analyses demonstrating their consistency with widely accepted correlations. Although the indicators are somewhat generic in nature, they are applied to Savannah River Site (SRS) waste tanks to provide a better, physically based estimate of the required mixing time. Waste storage tanks at SRS contain settled sludge which varies in

  17. Persistent ion beam induced conductivity in zinc oxide nanowires

    SciTech Connect

    Johannes, Andreas; Niepelt, Raphael; Gnauck, Martin; Ronning, Carsten

    2011-12-19

    We report persistently increased conduction in ZnO nanowires irradiated by ion beam with various ion energies and species. This effect is shown to be related to the already known persistent photo conduction in ZnO and dubbed persistent ion beam induced conduction. Both effects show similar excitation efficiency, decay rates, and chemical sensitivity. Persistent ion beam induced conduction will potentially allow countable (i.e., single dopant) implantation in ZnO nanostructures and other materials showing persistent photo conduction.

  18. Sub-Planck structure in a mixed state

    NASA Astrophysics Data System (ADS)

    Kumari, Asmita; Pan, Alok Kumar; Panigrahi, Prasanta K.

    2015-11-01

    The persistence of sub-Planck structure in phase space with loss of coherence is demonstrated in a mixed state, which comprises two terms in the density matrix. Its utility in carrying out Heisenberg-limited measurement and quantum parameter estimation have been shown. It is also shown that the mixed state performs equally well as the compass state for carrying out precision measurements. The advantage of using mixed state relies on the fact that such a state can be easier to prepare and may appear from pure states after partial loss of coherence. We explicate the effect of environment on these sub-Planck structures in the mixed state and estimates the time scale of complete decoherence.

  19. Persistent Fifth Aortic Arch with Coarctation

    PubMed Central

    Kim, Sue Hyun; Choi, Eun-Suk; Cho, Sungkyu; Kim, Woong-Han

    2016-01-01

    Persistent fifth aortic arch (PFAA) is a rare congenital anomaly of the aortic arch frequently associated with other cardiovascular anomalies, such as tetralogy of Fallot and aortic arch coarctation or interruption. We report the case of a neonate with PFAA with coarctation who successfully underwent surgical repair. PMID:26889445

  20. The role of persistence in chemical evaluations.

    PubMed

    Mackay, Donald; Hughes, Dianne M; Romano, M Luisa; Bonnell, Mark

    2014-10-01

    The initial stage in the assessment and priority setting of chemicals for their potential to cause harm to humans and the environment is usually a hazard assessment employing metrics for persistence, bioaccumulation, and inherent toxicity. This hazard assessment is followed, when necessary, by the more demanding task of risk assessment. Hazard assessment of data and processes influencing persistence are discussed, leading to a number of suggestions for more effective evaluation. These include 1) an initial focus on accurate data for intensive chemical partitioning and reaction half-life properties that are universally applicable as distinct from extensive properties that can be included later on a location-specific basis; 2) separate treatments of near-field and far-field exposures; 3) a focus on persistence and its effect on levels of exposure, especially for substances for which "time to exposure" is less than "time to degradation" and have been termed "pseudo-persistent." We show that "continuously present" is a better descriptor of this concern. Case studies illustrate and support these suggestions. Data on the intensive properties and on exposure pathways are best combined in evaluative multimedia mass balance models that can provide a clear depiction of the likely chemical fate, exposure routes, and levels. The information generated by the mass balance models can serve to justify and direct a full risk assessment that includes region-specific information on chemical quantities, estimates of exposure, and potential for adverse effects. PMID:24753402

  1. PERSISTENT, BIOACCUMULATIVE, AND TOXIC POLLUTANTS (PBTS)

    EPA Science Inventory

    Article describes the class of compounds known as persistent, bioaccumulative, and toxic pollutants (known as PBTs), including the mechanisms responsible for ability to build up the food chain and for causing adverse health effects and ecosystem damage. Exposure to numerous PBTs ...

  2. Paradoxical Understandings Regarding Adult Undergraduate Persistence

    ERIC Educational Resources Information Center

    Kasworm, Carol E.

    2014-01-01

    Historically, characteristics of student persistence and graduation completion were most often linked to strategies which honored the full-time residential younger undergraduate. Adult students have been viewed as high-risk and typically problematic students for continuous enrollment and degree completion. This article explores the key paradoxical…

  3. Anger Expression and Persistence in Young Children

    ERIC Educational Resources Information Center

    He, Jie; Xu, Qinmei; Degnan, Kathryn Amey

    2012-01-01

    This study investigated anger expression during toy removal (TR) in 92 young Chinese children, two to five years of age, and its relations to their persistence in responding to obstacles during two challenging tasks with highly desirable goals [TR and locked box (LB)] and one challenging task with a less desirable goal [impossible perfect circles…

  4. Persistence of Problematic Sexual Behaviors in Children

    ERIC Educational Resources Information Center

    Levesque, Mireille; Bigras, Marc; Pauze, Robert

    2012-01-01

    The purpose of this study was to identify personal and family predictors and correlates of persistence of problematic sexual behaviors (PSB) in children. Participants were the families of 49 children (ages 4-11 years) referred by Child Protective Services in 4 administrative districts of Quebec. Caregivers completed interviews and questionnaires…

  5. Persistence of Value-Driven Attentional Capture

    ERIC Educational Resources Information Center

    Anderson, Brian A.; Yantis, Steven

    2013-01-01

    Stimuli that have previously been associated with the delivery of reward involuntarily capture attention when presented as unrewarded and task-irrelevant distractors in a subsequent visual search task. It is unknown how long such effects of reward learning on attention persist. One possibility is that value-driven attentional biases are plastic…

  6. Study Circle Guide: Adult Student Persistence

    ERIC Educational Resources Information Center

    National Center for the Study of Adult Learning and Literacy (NCSALL), 2006

    2006-01-01

    This study circle was created by the National Center for the Study of Adult Learning and Literacy (NCSALL). The study circle is part of NCSALL's efforts to help connect research and practice in the field of adult basic education and adult literacy. The Adult Student Persistence Study Circle is one of a series of study circles that NCSALL has…

  7. Inchworm, Inchworm: Persistent Problems in Reading Education.

    ERIC Educational Resources Information Center

    McCullough, Constance M., Ed.

    The papers in this volume represent thoughts about the state of the art of teaching reading (with an emphasis on persistent problems) of many recognized authorities in the field of reading education. Eight of the articles were originally presented at a joint Reading Hall of Fame and International Reading Association (IRA) symposium at the IRA…

  8. TOXICITY PERSISTENCE IN PRICKLY PEAR CREEK, MONTANA

    EPA Science Inventory

    Instream toxicity tests using the larval fathead minnow Pimephales promelas and the cladoceran Ceriodaphnia reticulata were conducted on Prickly Pear Creek, Montana waters to study toxicity persistence in a stream. The toxicity source was Spring Creek, a tributary of Prickly Pear...

  9. The Enigmatic Persistence of Anorexia Nervosa

    PubMed Central

    Walsh, B. Timothy

    2014-01-01

    Objective In this review, based on recent advances in cognitive neuroscience, the author presents a formulation in which the marked persistence of anorexia nervosa can be usefully understood as a well-ingrained maladaptive habit. Method The author reviewed the relevant literature on the development and course of anorexia nervosa and interpreted critical features in light of developments in cognitive neuroscience. Results Anorexia nervosa is a well characterized disorder with remarkable persistence both across history and among affected individuals. Food restriction, the salient behavioral feature of the disorder, often begins innocently but gradually takes on a life of its own. Over time, it becomes highly entrenched and resistant to change through either psychological or pharmacological treatment. Cognitive neuroscience has described two related but distinct processes that underlie the acquisition of new patterns of behavior, namely, action-outcome and stimulus-response learning. It is likely that both processes are engaged in the development of anorexia nervosa and that stimulus-response learning (that is, habit formation) is critical to the persistence of the dieting behavior. Conclusions The formulation of the dieting behavior characteristic of anorexia nervosa as a well-entrenched habit provides a basis for understanding the striking persistence of this disorder. This model helps explain the resistance of anorexia nervosa to interventions that have established efficacy in related disorders and implies that addressing the dieting behavior is critical, especially early in the course of the illness, before it has become ingrained. PMID:23429750

  10. Persistence of Ebola Virus in Sterilized Wastewater

    PubMed Central

    2015-01-01

    In the wake of the ongoing 2014/2015 Ebola virus outbreak, significant questions regarding the appropriate handling of Ebola virus-contaminated liquid waste remain, including the persistence of Ebola virus in wastewater. To address these uncertainties, we evaluated the persistence of Ebola virus spiked in sterilized domestic sewage. The viral titer decreased approximately 99% within the first test day from an initial viral titer of 106 TCID50 mL–1; however, it could not be determined if this initial rapid decrease was due to aggregation or inactivation of the viral particles. The subsequent viral titer decrease was less rapid, and infectious Ebola virus particles persisted for all 8 days of the test. The inactivation constant (k) was determined to be −1.08 (2.1 days for a 90% viral titer decrease). Due to experimental conditions, we believe these results to be an upper bound for Ebola virus persistence in wastewater. Wastewater composition is inherently heterogeneous; subsequently, we caution that interpretation of these results should be made within a holistic assessment, including the effects of wastewater composition, dilution, and potential exposure routes within wastewater infrastructure. While it remains unknown if Ebola virus may be transmitted via wastewater, these data demonstrate a potential exposure route to infectious Ebola virus via wastewater and emphasize the value of a precautionary approach to wastewater handling in an epidemic response. PMID:26523283

  11. Persistence in eye movement during visual search

    NASA Astrophysics Data System (ADS)

    Amor, Tatiana A.; Reis, Saulo D. S.; Campos, Daniel; Herrmann, Hans J.; Andrade, José S.

    2016-02-01

    As any cognitive task, visual search involves a number of underlying processes that cannot be directly observed and measured. In this way, the movement of the eyes certainly represents the most explicit and closest connection we can get to the inner mechanisms governing this cognitive activity. Here we show that the process of eye movement during visual search, consisting of sequences of fixations intercalated by saccades, exhibits distinctive persistent behaviors. Initially, by focusing on saccadic directions and intersaccadic angles, we disclose that the probability distributions of these measures show a clear preference of participants towards a reading-like mechanism (geometrical persistence), whose features and potential advantages for searching/foraging are discussed. We then perform a Multifractal Detrended Fluctuation Analysis (MF-DFA) over the time series of jump magnitudes in the eye trajectory and find that it exhibits a typical multifractal behavior arising from the sequential combination of saccades and fixations. By inspecting the time series composed of only fixational movements, our results reveal instead a monofractal behavior with a Hurst exponent , which indicates the presence of long-range power-law positive correlations (statistical persistence). We expect that our methodological approach can be adopted as a way to understand persistence and strategy-planning during visual search.

  12. Persistence in eye movement during visual search

    PubMed Central

    Amor, Tatiana A.; Reis, Saulo D. S.; Campos, Daniel; Herrmann, Hans J.; Andrade, José S.

    2016-01-01

    As any cognitive task, visual search involves a number of underlying processes that cannot be directly observed and measured. In this way, the movement of the eyes certainly represents the most explicit and closest connection we can get to the inner mechanisms governing this cognitive activity. Here we show that the process of eye movement during visual search, consisting of sequences of fixations intercalated by saccades, exhibits distinctive persistent behaviors. Initially, by focusing on saccadic directions and intersaccadic angles, we disclose that the probability distributions of these measures show a clear preference of participants towards a reading-like mechanism (geometrical persistence), whose features and potential advantages for searching/foraging are discussed. We then perform a Multifractal Detrended Fluctuation Analysis (MF-DFA) over the time series of jump magnitudes in the eye trajectory and find that it exhibits a typical multifractal behavior arising from the sequential combination of saccades and fixations. By inspecting the time series composed of only fixational movements, our results reveal instead a monofractal behavior with a Hurst exponent , which indicates the presence of long-range power-law positive correlations (statistical persistence). We expect that our methodological approach can be adopted as a way to understand persistence and strategy-planning during visual search. PMID:26864680

  13. The Persistent Madness of Greek Hazing.

    ERIC Educational Resources Information Center

    Ruffins, Paul

    1998-01-01

    Origins and persistent reasons for college sorority and fraternity hazing, particularly in black organizations, are examined, including desire for domination, links to childhood abuse, and homoeroticism. The influences of tradition, peer pressure, the need to belong, and desire for solidarity are also considered. Reviews recent research on the…

  14. The Persistence of African American College Men

    ERIC Educational Resources Information Center

    Beale, Tyson J.

    2010-01-01

    This study explored the family dynamics of persistent African American college men. These students were typical Black males, not those pre-categorized as high-achieving or unprepared for college. The stories of participants revealed their strength, ambition, and intentions to successfully gain a baccalaureate degree. In general Black males are…

  15. Persistence of Salmonella typhimurium on Fabrics

    PubMed Central

    Wilkoff, Lee J.; Westbrook, Louise; Dixon, Glen J.

    1969-01-01

    The persistence of Salmonella typhimurium (V-31) on wool blanket, wool gabardine, cotton sheeting, cotton knit jersey, cotton terry cloth, and cotton wash-and-wear fabrics was studied. Three methods of exposure were employed to contaminate the fabrics: direct contact, aerosol, and a lyophilized mixture of bacteria and dust having a high content of textile fibers. After contamination, the fabrics were held in 35 or 78% relative humidity at 25 C. The persistence time of S. typhimurium on fabrics held in 35% relative humidity was substantially longer when the fabrics were contaminated by direct contact or by exposure to dust containing bacteria than when contaminated by exposure to aerosolized cultures. Viable bacterial populations persisted for 24 weeks at relatively high population densities on swatches of wool gabardine, cotton sheeting, cotton knit jersey, and cotton terry cloth exposed by direct contact and held in a humidity of 35%. In 78% humidity, bacterial populations persisted on the fabrics for relatively shorter periods of time regardless of the mode of contamination or fabric type. This organism retained its virulence for Swiss mice after being recovered from wool gabardine swatches held 8 weeks in humidities of 35 or 78% and from cotton terry cloth swatches held 6 weeks in the same humidities. Images PMID:4896883

  16. Persistence of Change: Fume Hood Campaign Lessons

    ERIC Educational Resources Information Center

    Feder, Elah; Robinson, Jennifer; Wakefield, Sarah

    2012-01-01

    Purpose: Sustainability initiatives typically operate for a limited time period, but it is often unclear whether they have lasting effects. The purpose of this paper is to examine a laboratory fume hood campaign, in order to identify factors that might contribute or detract from long-term change persistence. Design/methodology/approach: The…

  17. Persistence in eye movement during visual search.

    PubMed

    Amor, Tatiana A; Reis, Saulo D S; Campos, Daniel; Herrmann, Hans J; Andrade, José S

    2016-01-01

    As any cognitive task, visual search involves a number of underlying processes that cannot be directly observed and measured. In this way, the movement of the eyes certainly represents the most explicit and closest connection we can get to the inner mechanisms governing this cognitive activity. Here we show that the process of eye movement during visual search, consisting of sequences of fixations intercalated by saccades, exhibits distinctive persistent behaviors. Initially, by focusing on saccadic directions and intersaccadic angles, we disclose that the probability distributions of these measures show a clear preference of participants towards a reading-like mechanism (geometrical persistence), whose features and potential advantages for searching/foraging are discussed. We then perform a Multifractal Detrended Fluctuation Analysis (MF-DFA) over the time series of jump magnitudes in the eye trajectory and find that it exhibits a typical multifractal behavior arising from the sequential combination of saccades and fixations. By inspecting the time series composed of only fixational movements, our results reveal instead a monofractal behavior with a Hurst exponent , which indicates the presence of long-range power-law positive correlations (statistical persistence). We expect that our methodological approach can be adopted as a way to understand persistence and strategy-planning during visual search. PMID:26864680

  18. The Myth of Persistence of Vision Revisited.

    ERIC Educational Resources Information Center

    Anderson, Joseph; Anderson, Barbara

    1993-01-01

    Argues that "persistence of vision" myth (the succession of still images perceived as continuous motion) has a place in the history of film scholarship but can no longer be given currency in film theory. Suggests replacement of the concept of the passive viewer implied by the myth by an enlightened understanding of how viewers actually interface…

  19. Registered Nurse Persistence in Baccalaureate Education

    ERIC Educational Resources Information Center

    Krov, Kathleen Nadler

    2010-01-01

    There is a need to increase the number of baccalaureate prepared registered nurses to safely meet the complex healthcare needs of citizens of the United States. Since there is no research on the characteristics of registered nurse students persisting in baccalaureate education, this quantitative descriptive case study was designed to identify the…

  20. Characteristics of Learning Disabilities Persisting into Adolescence.

    ERIC Educational Resources Information Center

    Whyte, Lillian A.

    1984-01-01

    Describes characteristics of learning disabled teenagers. Describes results of a study of 331 secondary students who completed a self-report inventory showing that childhood learning disability characteristics persist into adolescence, most seriously in the areas of visual perception, fine motor skills, and the ability to write and make spatial…

  1. Prerequisites for Persistence in Distance Education

    ERIC Educational Resources Information Center

    Ekstrand, Britten

    2013-01-01

    In the last two decades, distance education has grown worldwide and is now established as a reliable educational method. Accompanying this development, questions about low rates of student persistence have come to interest governments, institutions, and university management. This article is based on an original local study at a university in…

  2. Persistent Marriage Regimes in Changing Times

    ERIC Educational Resources Information Center

    Fussell, Elizabeth; Palloni, Alberto

    2004-01-01

    Marriage among women in Latin America occurs early in life and is nearly universal in spite of the social and economic changes and instability in the region. We use demographic measures to illustrate the precociousness, persistence, and universality of marriage during the past 50 years. We argue that marriage is central to social life because…

  3. The persistence length of adsorbed dendronized polymers.

    PubMed

    Grebikova, Lucie; Kozhuharov, Svilen; Maroni, Plinio; Mikhaylov, Andrey; Dietler, Giovanni; Schlüter, A Dieter; Ullner, Magnus; Borkovec, Michal

    2016-07-21

    The persistence length of cationic dendronized polymers adsorbed onto oppositely charged substrates was studied by atomic force microscopy (AFM) and quantitative image analysis. One can find that a decrease in the ionic strength leads to an increase of the persistence length, but the nature of the substrate and of the generation of the side dendrons influence the persistence length substantially. The strongest effects as the ionic strength is being changed are observed for the fourth generation polymer adsorbed on mica, which is a hydrophilic and highly charged substrate. However, the observed dependence on the ionic strength is much weaker than the one predicted by the Odijk, Skolnik, and Fixman (OSF) theory for semi-flexible chains. Low-generation polymers show a variation with the ionic strength that resembles the one observed for simple and flexible polyelectrolytes in solution. For high-generation polymers, this dependence is weaker. Similar dependencies are found for silica and gold substrates. The observed behavior is probably caused by different extents of screening of the charged groups, which is modified by the polymer generation, and to a lesser extent, the nature of the substrate. For highly ordered pyrolytic graphite (HOPG), which is a hydrophobic and weakly charged substrate, the electrostatic contribution to the persistence length is much smaller. In the latter case, we suspect that specific interactions between the polymer and the substrate also play an important role. PMID:27353115

  4. The Academic Library Impact on Student Persistence

    ERIC Educational Resources Information Center

    Emmons, Mark; Wilkinson, Frances C.

    2011-01-01

    What impact does the academic library have on student persistence? This study explores the relationship between traditional library input and output measures of staff, collections, use, and services with fall-to-fall retention and six-year graduation rates at Association of Research Libraries member libraries. When controlling for race/ethnicity…

  5. The Contribution of Student Satisfaction to Persistence

    ERIC Educational Resources Information Center

    Schreiner, Laurie A.; Nelson, Denise D.

    2013-01-01

    This study of nearly 30,000 undergraduates at 61 four-year public and private institutions examines the influence of satisfaction on students' persistence in college. Data were collected using the Student Satisfaction Inventory (Schreiner & Juillerat, 1994) and were analyzed by class level. The hierarchical multiple regression analyses…

  6. RISK CHARACTERIZATION OF PERSISTENT NEUROTOXIC CONTAMINANTS

    EPA Science Inventory

    Neurotoxicity is an adverse change in structure or function of the central and/or peripheral nervous system following exposure to a chemical, physical, or biological agent. Thousands of chemicals have been estimated to have neurotoxic potential. Many persistent and bioaccumulat...

  7. High School Economic Composition and College Persistence

    ERIC Educational Resources Information Center

    Niu, Sunny X.; Tienda, Marta

    2013-01-01

    Using a longitudinal sample of Texas high school seniors of 2002 who enrolled in college within the calendar year of high school graduation, we examine variation in college persistence according to the economic composition of their high schools, which serves as a proxy for unmeasured high school attributes that are conductive to postsecondary…

  8. Remotely controllable mixing system

    NASA Technical Reports Server (NTRS)

    Belew, R. R. (Inventor)

    1986-01-01

    This invention relates to a remotely controllable mixing system in which a plurality of mixing assemblies are arranged in an annular configuration, and wherein each assembly employs a central chamber and two outer, upper and lower chambers. Valves are positioned between chambers, and these valves for a given mixing assembly are operated by upper and lower control rotors, which in turn are driven by upper and lower drive rotors. Additionally, a hoop is compressed around upper control rotors and a hoop is compressed around lower control rotors to thus insure constant frictional engagement between all control rotors and drive rotors. The drive rollers are driven by a motor.

  9. Persistence of undergraduate women in STEM fields

    NASA Astrophysics Data System (ADS)

    Pedone, Maggie Helene

    The underrepresentation of women in science, technology, engineering, and mathematics (STEM) is a complex problem that continues to persist at the postsecondary level, particularly in computer science and engineering fields. This dissertation explored the pre-college and college level factors that influenced undergraduate women's persistence in STEM. This study also examined and compared the characteristics of undergraduate women who entered STEM fields and non-STEM fields in 2003-2004. The nationally representative Beginning Postsecondary Students Longitudinal Study (BPS:04/09) data set was used for analysis. BPS:04/09 study respondents were surveyed three times (NPSAS:04, BPS:04/06, BPS:04/09) over a six-year period, which enabled me to explore factors related to long-term persistence. Astin's Input-Environment-Output (I-E-O) model was used as the framework to examine student inputs and college environmental factors that predict female student persistence (output) in STEM. Chi-square tests revealed significant differences between undergraduate women who entered STEM and non-STEM fields in 2003-2004. Differences in student demographics, prior academic achievement, high school course-taking patterns, and student involvement in college such as participation in study groups and school clubs were found. Notably, inferential statistics showed that a significantly higher proportion of female minority students entered STEM fields than non-STEM fields. These findings challenge the myth that underrepresented female minorities are less inclined to enter STEM fields. Logistic regression analyses revealed thirteen significant predictors of persistence for undergraduate women in STEM. Findings showed that undergraduate women who were younger, more academically prepared, and academically and socially involved in college (e.g., lived on campus, interacted with faculty, participated in study groups, fine arts activities, and school sports) were more likely to persist in STEM

  10. Guidelines for mixed waste minimization

    SciTech Connect

    Owens, C.

    1992-02-01

    Currently, there is no commercial mixed waste disposal available in the United States. Storage and treatment for commercial mixed waste is limited. Host States and compacts region officials are encouraging their mixed waste generators to minimize their mixed wastes because of management limitations. This document provides a guide to mixed waste minimization.

  11. Rotenone persistence model for montane streams

    USGS Publications Warehouse

    Brown, Peter J.; Zale, Alexander V.

    2012-01-01

    The efficient and effective use of rotenone is hindered by its unknown persistence in streams. Environmental conditions degrade rotenone, but current label instructions suggest fortifying the chemical along a stream based on linear distance or travel time rather than environmental conditions. Our objective was to develop models that use measurements of environmental conditions to predict rotenone persistence in streams. Detailed measurements of ultraviolet radiation, water temperature, dissolved oxygen, total dissolved solids (TDS), conductivity, pH, oxidation–reduction potential (ORP), substrate composition, amount of organic matter, channel slope, and travel time were made along stream segments located between rotenone treatment stations and cages containing bioassay fish in six streams. The amount of fine organic matter, biofilm, sand, gravel, cobble, rubble, small boulders, slope, pH, TDS, ORP, light reaching the stream, energy dissipated, discharge, and cumulative travel time were each significantly correlated with fish death. By using logistic regression, measurements of environmental conditions were paired with the responses of bioassay fish to develop a model that predicted the persistence of rotenone toxicity in streams. This model was validated with data from two additional stream treatment reaches. Rotenone persistence was predicted by a model that used travel time, rubble, and ORP. When this model predicts a probability of less than 0.95, those who apply rotenone can expect incomplete eradication and should plan on fortifying rotenone concentrations. The significance of travel time has been previously identified and is currently used to predict rotenone persistence. However, rubble substrate, which may be associated with the degradation of rotenone by adsorption and volatilization in turbulent environments, was not previously considered.

  12. Kaposi’s Sarcoma Herpesvirus Genome Persistence

    PubMed Central

    Juillard, Franceline; Tan, Min; Li, Shijun; Kaye, Kenneth M.

    2016-01-01

    Kaposi’s sarcoma-associated herpesvirus (KSHV) has an etiologic role in Kaposi’s sarcoma, primary effusion lymphoma, and multicentric Castleman’s disease. These diseases are most common in immunocompromised individuals, especially those with AIDS. Similar to all herpesviruses, KSHV infection is lifelong. KSHV infection in tumor cells is primarily latent, with only a small subset of cells undergoing lytic infection. During latency, the KSHV genome persists as a multiple copy, extrachromosomal episome in the nucleus. In order to persist in proliferating tumor cells, the viral genome replicates once per cell cycle and then segregates to daughter cell nuclei. KSHV only expresses several genes during latent infection. Prominent among these genes, is the latency-associated nuclear antigen (LANA). LANA is responsible for KSHV genome persistence and also exerts transcriptional regulatory effects. LANA mediates KSHV DNA replication and in addition, is responsible for segregation of replicated genomes to daughter nuclei. LANA serves as a molecular tether, bridging the viral genome to mitotic chromosomes to ensure that KSHV DNA reaches progeny nuclei. N-terminal LANA attaches to mitotic chromosomes by binding histones H2A/H2B at the surface of the nucleosome. C-terminal LANA binds specific KSHV DNA sequence and also has a role in chromosome attachment. In addition to the essential roles of N- and C-terminal LANA in genome persistence, internal LANA sequence is also critical for efficient episome maintenance. LANA’s role as an essential mediator of virus persistence makes it an attractive target for inhibition in order to prevent or treat KSHV infection and disease. PMID:27570517

  13. Persistence of brucellosis in pastoral systems.

    PubMed

    Racloz, V; Schelling, E; Chitnis, N; Roth, F; Zinsstag, J

    2013-04-01

    Regarded as a highly contagious, zoonotic disease with worldwide distribution, brucellosis is endemic in many countries and settings and is responsible for a considerable economic and health-related burden. Limited information is available on the persistence and prevalence of brucellosis in pastoral communities, due to the difficulty in gathering information and to their mobility. However, since these communities are economically and culturally dependent on livestock, it is important to further determine the cause of persistent disease and develop possible methods for its management. The two main objectives of this paper are to review the literature, identifying various epidemiological and social factors that affect the persistence of brucellosis in pastoral ecosystems, and determine prevalence estimates within these communities. The general trend of the summarised studies indicates low-level, relatively stable transmission of brucellosis in pastoral areas, when compared to transmission in intensive and semi-intensive peri-urban production systems. A formal mathematical analysis can be undertaken using matrix models or coupled differential equations. This allows an examination of the various conditions under which the number of diseased, infected or exposed animals remains stable. The authors examined an existing mathematical differential equation model for brucellosis in Mongolia for its equilibrium conditions and found it reasonably robust, though clearly more data are needed to estimate threshold densities for brucellosis transmission in other regions of the world. However, the results indicate the importance of livestock demographic determinants for brucellosis persistence. The paper concludes that brucellosis remains largely persistent in pastoral areas of the world, despite (varying) control efforts. Plans to control brucellosis in pastoral settings should include ecological considerations, such as sustaining ecosystem services in pastoral areas. This

  14. Persistence drives gene clustering in bacterial genomes

    PubMed Central

    Fang, Gang; Rocha, Eduardo PC; Danchin, Antoine

    2008-01-01

    Background Gene clustering plays an important role in the organization of the bacterial chromosome and several mechanisms have been proposed to explain its extent. However, the controversies raised about the validity of each of these mechanisms remind us that the cause of this gene organization remains an open question. Models proposed to explain clustering did not take into account the function of the gene products nor the likely presence or absence of a given gene in a genome. However, genomes harbor two very different categories of genes: those genes present in a majority of organisms – persistent genes – and those present in very few organisms – rare genes. Results We show that two classes of genes are significantly clustered in bacterial genomes: the highly persistent and the rare genes. The clustering of rare genes is readily explained by the selfish operon theory. Yet, genes persistently present in bacterial genomes are also clustered and we try to understand why. We propose a model accounting specifically for such clustering, and show that indispensability in a genome with frequent gene deletion and insertion leads to the transient clustering of these genes. The model describes how clusters are created via the gene flux that continuously introduces new genes while deleting others. We then test if known selective processes, such as co-transcription, physical interaction or functional neighborhood, account for the stabilization of these clusters. Conclusion We show that the strong selective pressure acting on the function of persistent genes, in a permanent state of flux of genes in bacterial genomes, maintaining their size fairly constant, that drives persistent genes clustering. A further selective stabilization process might contribute to maintaining the clustering. PMID:18179692

  15. Fish population persistence in hydrologically variable landscapes.

    PubMed

    Bond, Nick R; Balcombe, Stephen R; Crook, David A; Marshall, Jonathan C; Menke, Norbert; Lobegeiger, Jaye S

    2015-06-01

    Forecasting population persistence in environments subjected to periodic disturbances represents a general challenge for ecologists. In arid and semiarid regions, climate change and human water use pose significant threats to the future persistence of aquatic biota whose populations typically depend on permanent refuge waterholes for their viability. As such, habitats are increasingly being lost as a result of decreasing runoff and increasing water extraction. We constructed a spatially explicit population model for golden perch Macquaria ambigua (Richardson), a native freshwater fish in the Murray-Darling Basin in eastern Australia. We then used the model to examine the effects of increased aridity, increased drought frequency, and localized human water extraction on population viability. Consistent with current observations, the model predicted golden perch population persistence under the current climate and levels of water use. Modeled increases in local water extraction greatly increased the risk of population decline, while scenarios of increasing aridity and drought frequency were associated with only minor increases in this risk. We conclude that natural variability in abundances and high turnover rates (extinction/recolonization) of local populations dictate the importance of spatial connectivity and periodic cycles of population growth. Our study also demonstrates an effective way to examine population persistence in intermittent and ephemeral river systems by integrating spatial and temporal dynamics of waterhole persistence with demographic processes (survival, recruitment, and dispersal) within a stochastic modeling framework. The approach can be used to help understand the impacts of natural and anthropogenic drivers, including water resource development, on the viability of biota inhabiting highly dynamic environments. PMID:26465032

  16. Characterization of Mono- and Mixed-Culture Campylobacter jejuni Biofilms

    PubMed Central

    Ica, Tuba; Caner, Vildan; Istanbullu, Ozlem; Nguyen, Hung Duc; Ahmed, Bulbul; Call, Douglas R.

    2012-01-01

    Campylobacter jejuni, one of the most common causes of human gastroenteritis, is a thermophilic and microaerophilic bacterium. These characteristics make it a fastidious organism, which limits its ability to survive outside animal hosts. Nevertheless, C. jejuni can be transmitted to both humans and animals via environmental pathways, especially through contaminated water. Biofilms may play a crucial role in the survival of the bacterium under unfavorable environmental conditions. The goal of this study was to investigate survival strategies of C. jejuni in mono- and mixed-culture biofilms. We grew monoculture biofilms of C. jejuni and mixed-culture biofilms of C. jejuni with Pseudomonas aeruginosa. We found that mono- and mixed-culture biofilms had significantly different structures and activities. Monoculture C. jejuni biofilms did not consume a measurable quantity of oxygen. Using a confocal laser scanning microscope (CLSM), we found that cells from monoculture biofilms were alive according to live/dead staining but that these cells were not culturable. In contrast, in mixed-culture biofilms, C. jejuni remained in a culturable physiological state. Monoculture C. jejuni biofilms could persist under lower flow rates (0.75 ml/min) but were unable to persist at higher flow rates (1 to 2.5 ml/min). In sharp contrast, mixed-culture biofilms were more robust and were unaffected by higher flow rates (2.5 ml/min). Our results indicate that biofilms provide an environmental refuge that is conducive to the survival of C. jejuni. PMID:22179238

  17. Long persistent luminescence in the ultraviolet in Pb(2+)-doped Sr2MgGe2O7 persistent phosphor.

    PubMed

    Liang, Yanjie; Liu, Feng; Chen, Yafei; Sun, Kangning; Pan, Zhengwei

    2016-01-28

    We extend the persistent luminescence into the ultraviolet spectral region by developing a new ultraviolet persistent phosphor Sr2MgGe2O7:Pb(2+). The Sr2MgGe2O7:Pb(2+) phosphor exhibits strong persistent luminescence peaking at 370 nm and a long persistence time of >12 h after excitation. The phosphor also exhibits a photo-stimulated persistent luminescence capability. PMID:26691008

  18. Asymmetric antiproton debuncher: No bad mixing, more good mixing

    SciTech Connect

    Visnjic, V.

    1994-07-01

    An asymmetric lattice for the Fermilab Antiproton Debuncher is designed. The lattice has zero mixing between the pickups and the kickers (bad mixing) while the mixing in the rest of the machine (good mixing) can be varied (even during the operation of the machine) in order to optimize the stochastic cooling. As an example, a lattice with zero bad mixing and twice the good mixing is presented. The betatron cooling rate in this lattice is twice its present value.

  19. Mixed-Media Owls

    ERIC Educational Resources Information Center

    Schultz, Kathy

    2010-01-01

    The fun of creating collages is there are unlimited possibilities for the different kinds of materials one can use. In this article, the author describes how her eighth-grade students created an owl using mixed media.

  20. Persistence of mixed staphylococci assemblages following disinfection of hospital room surfaces.

    PubMed

    Sigler, V; Hensley, S

    2013-03-01

    The distribution of staphylococcal assemblages on surfaces in hospital rooms was assessed before and after daily disinfection with quaternary ammonia products. DNA was extracted from enrichment cultures of bacteria, which were swabbed from each of nine surface types, and subjected to analysis by staphylococci-specific, denaturing gradient gel electrophoresis. A genetic marker for Staphylococcus epidermidis/kloosii was detected on all surface types before and after cleaning, whereas markers for Staphylococcus aureus and Staphylococcus lugdunensis were detected on five surface types. Overall, genetic makers for several staphylococci known to colonize and infect humans remained ubiquitous in each room following daily disinfection practices. PMID:23374288

  1. Statistic versus stochastic characterization of persistent droughts

    NASA Astrophysics Data System (ADS)

    Gonzalez-Perez, J.; Valdes, J. B.

    2005-12-01

    Droughts are one of more devastating natural disasters. A drought event is always related with deficiency in precipitation over a time period. As longer are the drought periods, larger are the damages associated with, following a potential relationship. Additionally, the extension covered by an event also increases its impact, because it makes difficult to compensate the deficit from neighbourhood water resources. Therefore, the characterization of a drought by its persistent deficit, and the area over which it extends are main points to be carried on. The Standardized Precipitation Index (SPI) provides a statistical characterization of the deficits. Its computation, for different aggregation time scales, allows a persistence evaluation. Another more recent statistic that may be applied in drought characterization is the extreme persistent probability function (e.p.f.), which characterizes the persistence of extreme realizations in a random sequence. This work presents an analysis of the differences in performance of the SPI and the e.p.f. in the statistical characterization of a drought event. The inclusion of the persistency directly in the statistic gives to the e.p.f. an advantage over the SPI. Furthermore, the relationship between the e.p.f. and its mean frequency of recurrence is known. Thus, the e.p.f. may be applied to provide either statistic or stochastic characterization of a drought event. Both criteria were compared, showing that the stochastic characterization produces a better drought indicator. The stochastic characterization using the e.p.f. as a criterion yields the new Drought Frequency Index (DFI). The index is applicable to any random water related variable to identify drought events. Its main advantages over the SPI are the direct inclusion of persistence, and its larger robustness to the time scale. To incorporate the spatial extension in the characterization of a drought event, the new DFI may also be evaluated to characterize the drought

  2. Persistence of interest in science, technology, engineering and mathematics: An analysis of persisting and non-persisting students

    NASA Astrophysics Data System (ADS)

    White, Jeffry L.

    While there has been an increase in enrollment, interest in science, technology, engineering, and mathematics (STEM) has been declining on college campuses since 1967. Higher enrollment does not transfer to an increase in the number of minorities in the STEM fields. The majority-minority enrollment ratio is nearly 2:1 but the gap widens to 4:1 when it comes to graduation. In fact, underrepresented minorities (URM) earned only 12% of the STEM degrees awarded in 1998. When the higher attrition and lower graduation rates of URM are scrutinized, upwards of 60% changed majors or dropped out of STEM. Further investigation reveals the most frequently cited reasons for departure were loss of initial interest, developed a greater interest in another field, or were turned off by the STEM disciplines. A primarily exploratory study was conducted into the conditions necessary for academic interest in the STEM fields to persist. A model based on student engagement (Astin, 1977) and interest operations (Prenzel, 1988a) theories was used with a random sample of URM at universities participating in the Ohio Science and Engineering Alliance. Survey research was employed to investigate interest development and the effect of student retention programs and activities on such interest. The latter part of the study could not be fully examined when 95% reported not utilizing retention services. For the section on interest, an online survey using a 5-point Likert scale was validated using principal components analysis. A binominal logistic regression was used to predict membership in one of two possible groups: persisters and students at-risk for not persisting. The major conclusions are: (1) While 3 variables (feelings, learning and difficulty) were statistically significant only one, feelings was substantively significant. (2) Persistence increased 80.9% for each 1-unit increase in feelings and 9.9% for learning. (3) Persistence decreased 19.8% for each one-unit increase in difficulty

  3. Mixing of Supersonic Streams

    NASA Technical Reports Server (NTRS)

    Hawk, C. W.; Landrum, D. B.; Muller, S.; Turner, M.; Parkinson, D.

    1998-01-01

    The Strutjet approach to Rocket Based Combined Cycle (RBCC) propulsion depends upon fuel-rich flows from the rocket nozzles and turbine exhaust products mixing with the ingested air for successful operation in the ramjet and scramjet modes. It is desirable to delay this mixing process in the air-augmented mode of operation present during low speed flight. A model of the Strutjet device has been built and is undergoing test to investigate the mixing of the streams as a function of distance from the Strutjet exit plane during simulated low speed flight conditions. Cold flow testing of a 1/6 scale Strutjet model is underway and nearing completion. Planar Laser Induced Fluorescence (PLIF) diagnostic methods are being employed to observe the mixing of the turbine exhaust gas with the gases from both the primary rockets and the ingested air simulating low speed, air augmented operation of the RBCC. The ratio of the pressure in the turbine exhaust duct to that in the rocket nozzle wall at the point of their intersection is the independent variable in these experiments. Tests were accomplished at values of 1.0, 1.5 and 2.0 for this parameter. Qualitative results illustrate the development of the mixing zone from the exit plane of the model to a distance of about 10 rocket nozzle exit diameters downstream. These data show the mixing to be confined in the vertical plane for all cases, The lateral expansion is more pronounced at a pressure ratio of 1.0 and suggests that mixing with the ingested flow would be likely beginning at a distance of 7 nozzle exit diameters downstream of the nozzle exit plane.

  4. Mixing of Supersonic Streams

    NASA Technical Reports Server (NTRS)

    Hawk, C. W.; Landrum, D. B.; Muller, S.; Turner, M.; Parkinson, D.

    1998-01-01

    The Strutjet approach to Rocket Based Combined Cycle (RBCC) propulsion depends upon fuel-rich flows from the rocket nozzles and turbine exhaust products mixing with the ingested air for successful operation in the ramjet and scramjet modes. It is desirable to delay this mixing process in the air-augmented mode of operation present during low speed flight. A model of the Strutjet device has been built and is undergoing test to investigate the mixing of the streams as a function of distance from the Strutjet exit plane during simulated low speed flight conditions. Cold flow testing of a 1/6 scale Strutjet model is underway and nearing completion. Planar Laser Induced Fluorescence (PLIF) diagnostic methods are being employed to observe the mixing of the turbine exhaust gas with the gases from both the primary rockets and the ingested air simulating low speed, air augmented operation of the RBCC. The ratio of the pressure in the turbine exhaust duct to that in the rocket nozzle wall at the point of their intersection is the independent variable in these experiments. Tests were accomplished at values of 1.0, 1.5 and 2.0 for this parameter. Qualitative results illustrate the development of the mixing zone from the exit plane of the model to a distance of about 19 equivalent rocket nozzle exit diameters downstream. These data show the mixing to be confined in the vertical plane for all cases, The lateral expansion is more pronounced at a pressure ratio of 1.0 and suggests that mixing with the ingested flow would be likely beginning at a distance of 7 nozzle exit diameters downstream of the nozzle exit plane.

  5. ADVANCED MIXING MODELS

    SciTech Connect

    Lee, S; Richard Dimenna, R; David Tamburello, D

    2008-11-13

    The process of recovering the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank with one to four dual-nozzle jet mixers located within the tank. The typical criteria to establish a mixed condition in a tank are based on the number of pumps in operation and the time duration of operation. To ensure that a mixed condition is achieved, operating times are set conservatively long. This approach results in high operational costs because of the long mixing times and high maintenance and repair costs for the same reason. A significant reduction in both of these costs might be realized by reducing the required mixing time based on calculating a reliable indicator of mixing with a suitably validated computer code. The work described in this report establishes the basis for further development of the theory leading to the identified mixing indicators, the benchmark analyses demonstrating their consistency with widely accepted correlations, and the application of those indicators to SRS waste tanks to provide a better, physically based estimate of the required mixing time. Waste storage tanks at SRS contain settled sludge which varies in height from zero to 10 ft. The sludge has been characterized and modeled as micron-sized solids, typically 1 to 5 microns, at weight fractions as high as 20 to 30 wt%, specific gravities to 1.4, and viscosities up to 64 cp during motion. The sludge is suspended and mixed through the use of submersible slurry jet pumps. To suspend settled sludge, water is added to the tank as a slurry medium and stirred with the jet pump. Although there is considerable technical literature on mixing and solid suspension in agitated tanks, very little literature has been published on jet mixing in a large-scale tank. If shorter mixing times can be shown to support Defense Waste Processing Facility (DWPF) or other feed requirements, longer pump lifetimes can be achieved with associated operational cost and

  6. The persistence of American Indian health disparities.

    PubMed

    Jones, David S

    2006-12-01

    Disparities in health status between American Indians and other groups in the United States have persisted throughout the 500 years since Europeans arrived in the Americas. Colonists, traders, missionaries, soldiers, physicians, and government officials have struggled to explain these disparities, invoking a wide range of possible causes. American Indians joined these debates, often suggesting different explanations. Europeans and Americans also struggled to respond to the disparities, sometimes working to relieve them, sometimes taking advantage of the ill health of American Indians. Economic and political interests have always affected both explanations of health disparities and responses to them, influencing which explanations were emphasized and which interventions were pursued. Tensions also appear in ongoing debates about the contributions of genetic and socioeconomic forces to the pervasive health disparities. Understanding how these economic and political forces have operated historically can explain both the persistence of the health disparities and the controversies that surround them. PMID:17077399

  7. Persistent Hypoglycemia in Patient with Hodgkin's Disease

    PubMed Central

    Lim, Harold Cinco; Munshi, Lubna Bashir; Sharon, David

    2015-01-01

    Hypoglycemia is a rare complication of Hodgkin's disease. Several explanations have been postulated but the exact pathophysiology is not well understood. We are presenting a case of newly diagnosed Stage IV Hodgkin's disease that developed persistent and recurrent hypoglycemia despite giving glucagon, repeated 50% dextrose, and D5 and D10 continuous infusion. Hypoglycemia workup showed the C-peptide level to be low. Patient was suspected of having hypoglycemia related to lymphoma and was given a trial of prednisone which resolved the hypoglycemic episodes and made the patient euglycemic for the rest of his hospital stay. The presence of a substance that mimicked the effects of insulin was highly suspected. Several case reports strengthen the hypothesis of an insulin-like growth factor or antibodies secreted by the cancer cells causing hypoglycemia in Hodgkin's disease but none of them have been confirmed. Further investigation is warranted to more clearly define the pathophysiology of persistent hypoglycemia in patients with Hodgkin's disease. PMID:26839722

  8. SCORPION II persistent surveillance system update

    NASA Astrophysics Data System (ADS)

    Coster, Michael; Hunt, Cassandra

    2011-06-01

    This paper highlights the most recently added features and benefits available in the latest generation of Northrop Grumman SCORPION II persistent surveillance and target recognition systems. By leveraging smaller, lighter, and more power efficient SCORPION II sensor and universal gateway components, with foliage penetrating ad-hoc network communications, persistent field programmable systems that are easier to conceal can be optimized for both image capture and data exfiltration. In addition to the SCORPION II suite of sensor components, a growing list of over sixty different sensor and camera types from a variety of manufacturers have been integrated with the SCORPION Gateway family. In addition to updating several different COP systems, SCORPION and SCORPION II data can be directly processed using a common sensor status graphical user interface (GUI) that allows for viewing and analysis of images and sensor data from hundreds of SCORPION system gateways on single or multiple displays.

  9. Emotional persistence in online chatting communities

    NASA Astrophysics Data System (ADS)

    Garas, Antonios; Garcia, David; Skowron, Marcin; Schweitzer, Frank

    2012-05-01

    How do users behave in online chatrooms, where they instantaneously read and write posts? We analyzed about 2.5 million posts covering various topics in Internet relay channels, and found that user activity patterns follow known power-law and stretched exponential distributions, indicating that online chat activity is not different from other forms of communication. Analysing the emotional expressions (positive, negative, neutral) of users, we revealed a remarkable persistence both for individual users and channels. I.e. despite their anonymity, users tend to follow social norms in repeated interactions in online chats, which results in a specific emotional ``tone'' of the channels. We provide an agent-based model of emotional interaction, which recovers qualitatively both the activity patterns in chatrooms and the emotional persistence of users and channels. While our assumptions about agent's emotional expressions are rooted in psychology, the model allows to test different hypothesis regarding their emotional impact in online communication.

  10. UAV Cooperation Architectures for Persistent Sensing

    SciTech Connect

    Roberts, R S; Kent, C A; Jones, E D

    2003-03-20

    With the number of small, inexpensive Unmanned Air Vehicles (UAVs) increasing, it is feasible to build multi-UAV sensing networks. In particular, by using UAVs in conjunction with unattended ground sensors, a degree of persistent sensing can be achieved. With proper UAV cooperation algorithms, sensing is maintained even though exceptional events, e.g., the loss of a UAV, have occurred. In this paper a cooperation technique that allows multiple UAVs to perform coordinated, persistent sensing with unattended ground sensors over a wide area is described. The technique automatically adapts the UAV paths so that on the average, the amount of time that any sensor has to wait for a UAV revisit is minimized. We also describe the Simulation, Tactical Operations and Mission Planning (STOMP) software architecture. This architecture is designed to help simulate and operate distributed sensor networks where multiple UAVs are used to collect data.