Formation of Low Threshold Voltage Microlasers

Vertical cavity surface emitting lasers (VCSELs) with threshold voltages of 1.7V have been fabricated. The resistance-area product in these new vertical cavity lasers is comparable to that of edge-emitting lasers, and threshold currents as low as 3 mA have been measured. Molecular beam epitaxy was used to grow n-type mirrors, a quantum well active region, and a heavily Be-doped p-contact. After contact definition and alloying, passive high-reflectivity mirrors were deposited by reactive sputter deposition of SiO2/Si3N4 to complete the laser cavity

Dislalias orgánicas

Video educativo sobre las dislalias orgánicas en niños, diseñado para instruir sobre sus características principales y crear conciencia sobre la importancia de su detección temprana.Universidad del Nort

Room-Temperature Continuous-Wave Vertical-Cavity Single-Quantum-Well Microlaser Diodes

Room-temperature continuous and pulsed lasing of vertical-cavity, single-quantum-well, surface-emitting microlasers is achieved at ~983nm. The active Ga[sub][0-8]In[sub][0-2]As single quantum well is 100 [angstroms] thick. These microlasers have the smallest gain medium volumes among lasers ever built. The entire laser structure is grown by molecular beam epitaxy and the microlasers are formed by chemically assisted ion-beam etching. The microlasers are 3-50-μm across. The minimum threshold currents are 1.1 mA (pulsed) and 1.5 mA (CW)

Probability Density Function for Predicting Productivity in Masonry Construction Based on the Compatibility of a Crew

During the different phases of a masonry project, contractors collect detailed information about the labor productivity of its workers and the factors that influence productivity. Information includes quantitative data such as hours, activities, and tasks, and qualitative data such as ratings and personality factors. Personality factors have been found to be a key aspect that influences the compatibility of a crew and the productivity in masonry construction. This paper proposes a mathematical framework to determine how the compatibility between the workers in a crew can be used to predict productivity. A standard method for quantifying personality is used to determine the compatibility of a crew and empirically define a probability density to predict productivity. The probability density determines, for a given compatibility, the average productivity for a crew. The most interesting part of this probability density is that it accounts for variations in the productivity, resulting from the interaction and the relationships between the workers in a crew. The proposed probability distribution can be used to make more realistic predictions, by calculating confidence intervals, of the productivity of masonry crews and to better estimate times of construction, avoid crew conflicts, and find practical ways to increase production

Integrating Facility Management Information into Building Information Modelling using COBie: Current Status and Future Directions

Building Information Modelling (BIM) has been implemented by architecture, engineering and construction (AEC) firms since it effectively manages and integrates information throughout the building life cycle bringing long term benefits compared to existing practices. BIM models serve as communication between design and construction phases. These models are used to determine geometry details, resolve constructability problems, track the types of materials, represent functional characteristics, and produce workflows among others. However, the benefits of BIM have not been fully extended to the operations and maintenance phase. Once the building is finished, the owner still needs the handover of paper documents to complete the information required to support the facility management phase. Therefore, to help owners extend information support throughout the building life cycle, this study proposes a process model to collect information required for facility management and incorporate it into BIM. A Construction Operations Building Information Exchange (COBie) approach is used to capture essential information to support facility management as it is created in design and construction. By capturing all the information, owners may be able to directly import data into maintenance management systems to support facility operations. Future directions are also discussed

Low-Threshold Electrically Pumps Vertical-Cavity Surface-Emitting Microlasers

Vertical-cavity electrically driven lasers with three GaInAs quantum wells and diameters of several μm exhibit room-temperature pulsed current thresholds as low as 1.3mA with 958 nm output wavelength

End-to-end GRU model for construction crew management

Crew management is critical towards improving construction task productivity. Traditional methods for crew management on-site are heavily dependent on the experience of site managers. This paper proposes an end-to-end Gated Recurrent Units (GRU) based framework which provides site managers a more reliable and robust method for managing crews and improving productivity. The proposed framework predicts task productivity of all possible crew combinations, within a given size, from the pool of available workers using an advanced GRU model. The model has been trained with an existing database of masonry work and was found to outperform other machine learning models. The results of the framework suggest which crew combinations have the highest predicted productivity and can be used by superintendents and project managers to improve construction task productivity and better plan future projects

Five Strategies for Teaching Vocabulary As a Process

Building vocabulary is an important component of any reading program; it is a crucial comprehension skill. In fact, Davis (1968), in an analysis of comprehension skills, found word knowledge to be the key factor in comprehension. However, vocabulary has often been relegated to a secondary position in the scheme of language development, and no real systematic program for vocabulary building in reading or language arts course really exists (0\u27 Rourke, 1974). Additionally, the approaches to vocabulary study have long emphasized product over process (Brooks, 1986). Students have been presented with long lists of often unrelated terms that they could study and memorize for a test only to purposefully forget them following the quiz. Yet, readers need to expand their vocabulary range, and speakers require an ever increasing number of specific terms to communicate fully and effectively at various levels. How then does the teacher incorporate vocabulary study into the classroom? A few process oriented strategies seem to be the answer for meaningful vocabulary development and retention. In this paper, five strategies for vocabulary as a process are provided

Compatibility of Personality and Productivity: An Analysis of the Relationship with Construction Crews

The labor productivity of a crew depends on how efficiently workers are used in the construction process. Skills, capabilities, resources, and even personality affect the efficiency of the workers and may have an impact on the productivity of their crew. This paper illustrates how the personality profiles of the workers in a crew can be used to determine the relationship between compatibility of personality and productivity. Masons working in eight live construction projects completed the big five of personality to indicate their personality traits. Based on the personality traits, the compatibility of the crews was calculated. Productivity at the task-level was measured to determine the performance of the crews. Various statistical analyses are performed to establish the relationship between compatibility and crew productivity and the true value of the coefficient (and its likeliness). The results indicate that there is a high positive correlation between compatibility of personality and productivity at the task-level (rs = 0.758). Results also indicate that in the worst case scenario, there is a moderate correlation between compatibility and productivity (rs > 0.3; probability: 0.728). The implications of the relationship for managing crews in construction projects is discussed