We investigated students’ use of Newton’s second law in mechanics and electromagnetism contexts by interviewing students in a two-semester calculusbased physics course. We observed that students’ responses are consistent with three mental models, Newtonian, Aristotelian, and a hybrid model formed with elements of the first two models. These models appeared in mechanics contexts and were transfe...

We present observations of molecular high-energy radiation probes and report the first detections of CO + toward W3 IRS5, a source containing ultracom-pact HII regions. UV radiation and X-rays from the central objects may enhance molecules due to photodissociation and ionization processes. To study the effects on the immediate YSO environment, we are developing time-and depth-dependant chemical...

be a distinct systematic difference between the separations depending on the pressure used in the source. It is conceivable that this is real. On the other hand it may be due to wide variation in intensities of the, unresolved components. If we assume that the fourth and fifth components have zero intensities on the low pressure plates and theoretical intensities on the high pressure plates, th...

background and aims. the antioxidant and anti-inflammatory properties of propolis were studied. since saliva contains antioxidants and radiotherapy of the head and neck mainly affects the saliva, salivary antioxidant defensive mechanism is compromised with oxidative stress produced by radiation therapy. therefore, the aim of the present study was to investigate the effect of propolis on salivar...

Solar radiation models for predicting the average daily and hourly global radiation, beam radiation and diffuse radiation are reviewed in this paper. Seven models using the Ångström– Prescott equation to predict the average daily global radiation with hours of sunshine are considered. The average daily global radiation for Hong Kong (22.3 N latitude, 114.3 E longitude) is predicted. Estimations...

A major objective of the Atmospheric Radiation Measurement (ARM) Program is to test and improve parameterizations for cloud and radiative processes. A common strategy adopted for this purpose within the ARM science team is to utilize single-column models (SCMs) driven by appropriate boundary conditions derived from observations, so as to isolate the parameterizations themselves. In practice, ac...

Fading is the time-dependent variation in transmitted signal strength through a complex medium due to interference or temporally evolving multipath scattering. In this paper we use random matrix theory (RMT) to establish a first-principles model for fading, including both universal and nonuniversal effects. This model provides a more general understanding of the most common statistical models (...

Determination of river runoff is essential in design and construction of most hydraulic structures including dams. In rivers with no measurement stations, the hydraulic models can be used for data estimation.  SWAT is one of the most widely-used numerical models. In this model, input influential meteorological data as precipitation, temperature, wind speed, solar radiation and relative humidity...

The present study compared simple thermal indices and the indices derived from energy budget models in the northwest of Iran. For this purpose, the air temperature, solar radiation, relative humidity, cloud, cover and wind speed of 13 meteorological stations in the northwest of Iran during the  the period of 1986 to 2007 were selected for comparison. The results which were extracted using Biokl...