544 research outputs found

    The ecological distribution of monitor lizards (Reptilia, Varanidaej in Nigeria

    Get PDF
    The ecological distribulion of three varanid lizards (Varanus exanthematicus, K niloticus niloticus, and V. niloticus ornatusj in Nigeria is studied in the present paper, from both literature records and long-term field ecological research. V. exanthematicus is present only in central and northern Nigeria, where it seerns to be widespread and locally cornrnon in the Guinea savanna vegetation zone, but rnay be found in several spots in the Sudan savanna and even in the Sahel savanna. V. n. ornatus is confined to the extreme south of the country, ¡.e. in the coastal mangrove and deltaic swamp rainforest habita%, and also in the moist lowland rainforest. The distribution of V. n. niloticus remains controversial. It is widespread in the Sudan savanna and in the Guinea savanna, but appears only rarely in the derived savanna and rnoist lowland forest vegetation zones. Despite a few old literature records, it seerns to be absent frorn the rainforest blocks of southern Nigeria. Annual precipitation regimes seem to condition greatly the general distribution patterns of the Nigerian varanids, which are quite generalist in terms of habitat preferences within each rnajor climatic-vegetation zone. Key words: Varanidae, Distribution, Ecology, Nigeria.The ecological distribulion of three varanid lizards (Varanus exanthematicus, K niloticus niloticus, and V. niloticus ornatusj in Nigeria is studied in the present paper, from both literature records and long-term field ecological research. V. exanthematicus is present only in central and northern Nigeria, where it seerns to be widespread and locally cornrnon in the Guinea savanna vegetation zone, but rnay be found in several spots in the Sudan savanna and even in the Sahel savanna. V. n. ornatus is confined to the extreme south of the country, ¡.e. in the coastal mangrove and deltaic swamp rainforest habita%, and also in the moist lowland rainforest. The distribution of V. n. niloticus remains controversial. It is widespread in the Sudan savanna and in the Guinea savanna, but appears only rarely in the derived savanna and rnoist lowland forest vegetation zones. Despite a few old literature records, it seerns to be absent frorn the rainforest blocks of southern Nigeria. Annual precipitation regimes seem to condition greatly the general distribution patterns of the Nigerian varanids, which are quite generalist in terms of habitat preferences within each rnajor climatic-vegetation zone. Key words: Varanidae, Distribution, Ecology, Nigeria.The ecological distribulion of three varanid lizards (Varanus exanthematicus, K niloticus niloticus, and V. niloticus ornatusj in Nigeria is studied in the present paper, from both literature records and long-term field ecological research. V. exanthematicus is present only in central and northern Nigeria, where it seerns to be widespread and locally cornrnon in the Guinea savanna vegetation zone, but rnay be found in several spots in the Sudan savanna and even in the Sahel savanna. V. n. ornatus is confined to the extreme south of the country, ¡.e. in the coastal mangrove and deltaic swamp rainforest habita%, and also in the moist lowland rainforest. The distribution of V. n. niloticus remains controversial. It is widespread in the Sudan savanna and in the Guinea savanna, but appears only rarely in the derived savanna and rnoist lowland forest vegetation zones. Despite a few old literature records, it seerns to be absent frorn the rainforest blocks of southern Nigeria. Annual precipitation regimes seem to condition greatly the general distribution patterns of the Nigerian varanids, which are quite generalist in terms of habitat preferences within each rnajor climatic-vegetation zone. Key words: Varanidae, Distribution, Ecology, Nigeria

    Long-Term Optical Observations Of Two Lmxbs: Uw Crb (=Ms 1603+260) And V1408 Aql (=4U 1957+115)

    Get PDF
    We present new optical photometry of two low-mass X-ray binary stars, UW CrB (MS 1603+260) and V1408 Aql (4U 1957+115). UW CrB is an eclipsing binary and we refine its eclipse ephemeris and measure an upper limit to the rate of change of its orbital period, vertical bar P vertical bar < 4.2 x 10(-11) (unitless). The light curve of UW CrB shows optical counterparts of type I X-ray bursts. We tabulate the times, orbital phases, and fluences of 33 bursts and show that the optical flux in the bursts comes primarily from the accretion disk, not from the secondary star. The new observations are consistent with a model in which the accretion disk in UW CrB is asymmetric and precesses in the prograde direction with a period of similar to 5.5 days. The light curve of V1408 Aql has a low-amplitude modulation at its 9.33 hr orbital period. The modulation remained a nearly pure sine curve in the new data as it was in 1984 and 2008, but its mean amplitude was lower, 18% against 23% in the earlier data. A model in which the orbital modulation is caused by the varying aspect of the heated face of the secondary star continues to give an excellent fit to the light curve. We derive a much improved orbital ephemeris for the system.NSF 0958783Astronom

    The Assessment Plan in Action: Business Communication, A Core Course

    Get PDF
    Accrediting agencies and state legislatures frequently require universities to provide methods of assessing student performance. Continuous improvement for accreditation drives the assessment movement. This paper describes a six-semester study conducted at a regional university accredited by the Southern Association of Colleges and Schools (SACS) and the Association to Advance Collegiate Schools of Business (AACSB). The study conducted from Fall 2006 to Spring 2009 encompassed six objectives related to communication mandated by the Texas Higher Education Coordinating Board. The study involved 2,562 students in 87 sections of the business communication course. Embedded questions and assignment review were the methods of assessment used. The findings showed clear improvement in some areas and additional improvement needed in others

    Optical and Infrared Light Curves of the Eclipsing X-ray Binary V395 Car = 2S 0921-630

    Get PDF
    We present results of optical and infrared photometric monitoring of the eclipsing low-mass X-ray binary V395 Car (2S 0921-630). Our observations reveal a clear, repeating orbital modulation with an amplitude of about one magnitude in B, and V and a little less in J. Combining our data with archival observations spanning about 20 years, we derive an updated ephemeris with orbital period 9.0026+/-0.0001d. We attribute the modulation to a combination of the changing aspect of the irradiated face of the companion star and eclipses of the accretion disk around the neutron star. Both appear to be necessary as a secondary eclipse of the companion star is clearly seen. We model the B, V, and J lightcurves using a simple model of an accretion disk and companion star and find a good fit is possible for binary inclinations of 82.2+/-1.0 degrees. We estimate the irradiating luminosity to be about 8x10^35 erg/s, in good agreement with X-ray constraints.Comment: 6 pages, accepted for publication in MNRA

    Assessment Measures and Rubrics in a Business Communication Course

    Get PDF
    Assessment to assure continuous improvement has increasingly become a requirement imposed by accrediting agencies and state legislatures on secondary and post-secondary schools. This paper describes a seven-semester study conducted at a regional university accredited by the Southern Association of Colleges and Schools (SACS) and the Association to Advance Collegiate Schools of Business (AACSB). Using existing course assignments in the Business Communication course, the study, conducted from fall 2006 through fall 2009, measured student performance related to six state-mandated communication objectives. The faculty used the results to close the loop for continuous improvement, the driving force of the assessment movement

    The Oral Presentation: Enhancing the Experience in an Online Business Communication Course

    Get PDF
    This study addressed student and faculty experiences in using a commercially available website to facilitate the delivery and evaluation of student presentations in the online business communication course. Of the students enrolled in online business communication, 75 students participated in the study by sharing their perceptions of the effectiveness of the oral presentation process. Additionally, their faculty members assessed the process from the instructor’s perspective. The findings and conclusion revealed that the process provided useful student feedback and was more effective than pedagogical methods tried before

    The Structure Of The Accretion Disk In The ADC Source 4U 1822-371

    Get PDF
    The low-mass X-ray binary (LMXB) 4U 1822-371 has an accretion disk corona (ADC) that scatters X-ray photons from the inner disk and neutron star out of the line of sight. It has a high orbital inclination and the secondary star eclipses the disk and ADC. We have obtained new time-resolved UV spectrograms and V- and I-band photometry of 4U 1822-371. The large quadratic term in our new optical eclipse ephemeris confirms that the system has an extremely high rate of mass transfer and mass accretion. The C IV lambda lambda = 1548 - 1550 angstrom emission line has a half width of similar to 4400 km/s, indicating a strong, high velocity wind is being driven off the accretion disk. Near the disk the wind is optically thick in UV, V, and J and the eclipse analysis shows that in V and J the optically thick wind extends nearly to the outer edge of the disk. The ADC must also extend vertically to a height equal to approximately half the disk radius.Astronom

    Business Meal Etiquette: A Survey Of Student Awareness And Preferences

    Get PDF
    The business meal is a popular activity in the workplace and is often included as part of the interview process. Sometimes it is used as a screening mechanism to determine if a candidate possesses certain social (soft) skills suited for a company. Thus, it is fitting that college students understand business meal etiquette as they embark on their careers. This article reports the findings of a survey of students’ awareness of business meal etiquette and their preferences for possible training and development
    • …
    corecore