502 research outputs found
The Bases for Attendance Control with Procedure for Secondary School Pupil Accounting
The large number of absentees among secondary school pupils emphasizes the necessity for renewed effort toward accuracy in checking attendance and eliminating unnecessary absence and tardiness
Measuring the Values for Time
Most economic models for time allocation ignore constraints on what people can actually do with their time. Economists recently have emphasized the importance of considering prior consumption commitments that constrain behavior. This research develops a new model for time valuation that uses time commitments to distinguish consumers' choice margins and the different values of time these imply. The model is estimated using a new survey that elicits revealed and stated preference data on household time allocation. The empirical results support the framework and find an increasing marginal opportunity cost of time as longer time blocks are used.
Field Test for Repellency of Cedarwood Oil and Cedrol to Little Fire Ants
Eastern redcedars (Juniperus virginiana L.) are an abundant renew- able resource and represent a potential source of valuable natural products that may serve as natural biocides. The aromatic wood can be extracted to obtain cedarwood oil (CWO) and critical carbon dioxide (CO2) extraction of eastern redcedars gives both high yields and high quality CWO. In this study, CO2-derived CWO and cedrol, the most abundant component of CWO, were field-tested for repellency against the little fire ant (LFA), Wasmannia auropunctata Roger, in a Hawaiian macadamia orchard. Field tests were conducted using chopsticks baited with peanut-butter placed in established LFA trails on macadamia tree trunks and branches. The chopsticks and any ants present were collected after ca. 24 hours and the number of ants determined by visual counting. Four treatments were compared: Hexane only control; mineral oil; CWO; and cedrol. Control chopsticks and chopsticks treated with mineral oil had very high numbers of ants and were statistically equivalent. The CWO-treated chopsticks had significantly fewer LFAs than all the other treatments. Chopsticks treated with cedrol had fewer ants than the control chopsticks but more than the chopsticks treated with CWO. This research suggests that CWO extracts from J. virginianna may provide a renewable source of a natural ant repellent and could help manage this invasive pest
Short Run Constraints and the Increasing Marginal Value of Time in Recreation
Leisure activities such as local recreation trips usually take place in discrete blocks of time that are surrounded by time devoted to other commitments. It can be costly to transfer time between blocks to allow for longer outings. These observations affect the value of time within those blocks and suggest that traditional methods for valuing time using labor markets miss important considerations. This paper presents a new model for time valuation that uses non-employment time commitments to infer the shadow value of time spent in recreation. A unique survey that elicited revealed and stated preference data on household time allocation is used to implement the model. The results support the conclusion that there is an increasing marginal value of time for recreation as the trip length increases.
Effects of radiation therapy on tissue and serum concentrations of tumour associated trypsin inhibitor and their prognostic significance in rectal cancer patients
<p>Abstract</p> <p>Background</p> <p>We have previously demonstrated that elevated concentrations of tumour-associated trypsin inhibitor (TATI) in both tumour tissue (t-TATI) and in serum (s-TATI) are associated with a poor prognosis in colorectal cancer patients. It was also found that s-TATI concentrations were lower in patients with rectal cancer compared to patients with colon cancer. In this study, we investigated the effects of neoadjuvant radiotherapy (RT) on concentrations of t-TATI and s-TATI in patients with rectal cancer.</p> <p>Methods</p> <p>TATI was analysed in serum, normal mucosa and tumour tissue collected at various time points in 53 rectal cancer patients enrolled in a case-control study where 12 patients received surgery alone, 20 patients 5 Ă 5 Gy (short-term) preoperative RT and 21 patients 25 Ă 2 Gy (long-term) preoperative RT. T-TATI was analysed by immunohistochemistry and s-TATI was determined by an immunofluorometric assay. Mann-Whitney U test and Wilcoxon Z (Z) test were used to assess t-TATI and s-TATI concentrations in relation to RT. Spearman's correlation (R) test was used to explore the associations between t-TATI, s-TATI and clinicopathological parameters. Overall survival (OS) according to high and low t-TATI and s-TATI concentrations was estimated by classification and regression tree analysis, Kaplan-Meier analysis and the log rank test.</p> <p>Results</p> <p>RT did not affect concentrations of t-TATI or s-TATI. In patients receiving short-term but not long-term RT, s-TATI concentrations were significantly higher 4 weeks post surgery than in serum drawn prior to surgery (Z = -3.366, P < 0.001). T-TATI expression correlated with male gender (R = 0.406, P = 0.008). High t-TATI expression in surgical specimens was associated with a significantly shorter OS (P = 0.045). S-TATI concentrations in serum drawn at all time points were associated with an impaired OS (P = 0.035 before RT, P = 0.001 prior to surgery, P = 0.043 post surgery). At all time points, s-TATI correlated with higher age (P < 0.001-0.021) and with increased s-creatinine concentrations assessed prior to surgery (P = 0.041).</p> <p>Conclusions</p> <p>The results presented here further validate the utility of t-TATI and s-TATI as prognostic biomarkers in patients with rectal cancer, independent of neoadjuvant RT.</p
Comparison of thermal stability in MAX211 and 312 phases
The susceptibility of four MAX phases (Ti2AlC, Cr2AlC, Ti3AlC2, and Ti3SiC2) to high-temperature thermal dissociation in vacuum has been investigated using in-situ neutron diffraction. In high vacuum, these phases decomposed above 1400°C through the sublimation of M and A elements, forming a surface coating of MC. The apparent activation energies for the decomposition of sintered Ti3SiC2, Ti3AlC2, and Ti2AlC were determined to be 179.3, -71.9, and 85.7 kJ molâ1, respectively. The spontaneous release of Ti2AlC and TiC from de-intercalation during decomposition of Ti3AlC2 resulted in a negative activation energy
Public Benefits of Undeveloped Lands on Urban Outskirts: Non-Market Valuation Studies and their Role in Land Use Plans
Over the past three decades, the economics profession has developed methods for estimating the public benefits of green spaces, providing an opportunity to incorporate such information into land-use planning. While federal regulations routinely require such estimates for major regulations, the extent to which they are used in local land use plans is not clear. This paper reviews the literature on public values for lands on urban outskirts, not just to survey their methods or empirical findings, but to evaluate the role they have played--or have the potential to play-- in actual land use plans. Based on interviews with authors and representatives of funding agencies and local land trusts, it appears that academic work has had a mixed reception in the policy world. Reasons for this include a lack of interest in making academic work accessible to policy makers, emphasizing revealed preference methods which are inconsistent with policy priorities related to nonuse values, and emphasis on benefit-cost analyses. Nevertheless, there are examples of success stories that illustrate how such information can play a vital role in the design of conservation policies. Working Paper 07-2
Origin of congenital coronary arterio-ventricular fistulae from anomalous epicardial and myocardial development.
Coronary Artery Fistulae (CAFs) are cardiac congenital anomalies consisting of an abnormal communication of a coronary artery with either a cardiac chamber or another cardiac vessel. In humans, these congenital anomalies can lead to complications such as myocardial hypertrophy, endocarditis, heart dilatation, and failure. Unfortunately, despite their clinical relevance, the aetiology of CAFs remains unknown. In this work, we have used two different species (mouse and avian embryos) to experimentally model CAFs morphogenesis. Both conditional Itga4 (alpha 4 integrin) epicardial deletion in mice and cryocauterisation of chick embryonic hearts disrupted epicardial development and ventricular wall growth, two essential events in coronary embryogenesis. Our results suggest that myocardial discontinuities in the embryonic ventricular wall promote the early contact of the endocardium with epicardial-derived coronary progenitors at the cardiac surface, leading to ventricular endocardial extrusion, precocious differentiation of coronary smooth muscle cells, and the formation of pouch-like aberrant coronary-like structures in direct connection with the ventricular lumen. The structure of these CAF-like anomalies was compared with histopathological data from a human CAF. Our results provide relevant information for the early diagnosis of these congenital anomalies and the molecular mechanisms that regulate their embryogenesis.The authors thank Dr. A. Rojas (CABIMER, Sevilla, Spain) and Prof. Thalia
Papayannopoulou (University of Washington, WA, USA) for sharing with us the G2-
Gata4-Cre and Itga4-floxed mouse lines, respectively. We also thank Vanessa
Benhamo (Institut Imagine) for her expert support with HREM. Finally, we thank all
members of âDeCAâ laboratory (University of MĂĄlaga, MĂĄlaga, Spain), and the âHeart
Morphogenesisâ laboratory (Institut Imagine and Institut Pasteur, Paris, France) for
their help and fruitful discussions on this paper. This work was supported by the
Spanish Ministry of Science, R+D+i National Programme [grants RTI2018-095410-RBI00 and PID2021-122626-OB-I00], Spanish Ministry of Science-ISCIII [grant number
RD16/0011/0030], and University of MĂĄlaga [grant number UMA18-FEDERJA-146] to
[JMPP]; ConsejerĂa de Salud y Familias, Junta de AndalucĂa [grant number PIER-0084-
2019] to [JAGD]; University of MĂĄlaga [grant number I Plan Propio-UMA-A.4] to [ARV];
Spanish Ministry of Science, Innovation, and Universities (MCIU) (CIBER CV) [grant
numbers PID2019-104776RB-I00 and CB16/11/00399] to [JLDLP].S
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