Undocumented worker employment and firm survivability

Do firms employing undocumented workers have a competitive advantage? Using administrative data from the state of Georgia, this paper investigates the incidence of undocumented worker employment across firms and how it affects firm survival. Firms are found to engage in herding behavior, being more likely to employ undocumented workers if competitors do. Rivals' undocumented employment harms firms' ability to survive while firms' own undocumented employment strongly enhances their survival prospects. This finding suggests that firms enjoy cost savings from employing lower-paid undocumented at workers wages less than their marginal revenue product. The herding behavior and competitive effects are found to be much weaker in geographically broad product markets, where firms have the option to shift labor-intensive production out of state or abroad.Competition

Undocumented Worker Employment and Firm Survival

Do firms employing undocumented workers have a competitive advantage? Using administrative data from the state of Georgia, this paper investigates the incidence of undocumented worker employment across firms and how it affects firm survival. Firms are found to engage in herding behavior, being more likely to employ undocumented workers if competitors do. Rivals' undocumented employment harms firms' ability to survive, while firms' own undocumented employment strongly enhances their survival prospects. This suggests that firms enjoy cost savings from employing lower-paid undocumented workers at wages less than their marginal revenue product. The herding behavior and competitive effects are found to be much weaker in geographically broad product markets, where firms have the option to shift labor-intensive production out of state or abroad.undocumented workers, firm dynamics, monopsony, immigration policy

Development and validation of a smart system for medullation and diameter assessment of alpaca, llama and mohair fibres

Medullated fibres, due to their higher resistance to bending and pressure, constitute a problem for the textile industry. Thus, having practical instruments to identify them is essential. Therefore, the aim of this research was to develop and validate a novel, swift, automatic system (referred to as S-Fiber Med) for medullation and diameter assessment of animal fibres based on artificial intelligence. The medullation of 88 samples of alpaca, llama and mohair fibres (41, 43 and 4, respectively) was evaluated. Additionally, 269 samples of alpacas were considered for average fibre diameter (AFD) and the results were compared with the Portable Fiber Tester (PFT) and Optical Fibre Diameter Analyser (OFDA) methods (72 and 197 samples, respectively). The preparation of each sample to be analysed followed the procedure described in IWTO-8-2011. Version 5 of “You Only Look Once” and DenseNet models were used to recognise the type of medullation and diameter of the fibres, respectively. Within each image (n = 661 for alpaca), all fibres were labelled (as Non-Medullated, Fragmented Medulla, Uncontinuous Medulla, Continuous Medulla and Strongly Medullated) using the LabelImg tool. Data augmentation technique was applied to obtain 3 966 images. Such data set was divided into 3 576 and 390 images for training and test data, respectively. For mohair samples (n = 321), a similar process was carried out. The data to train the model used to infer the diameter contained 16 446 fibres labelled with his respective AFD. A complementary hardware composed of three subsystems (mechanical, electronic, and optical) was developed for evaluation purposes. T-test, Pearson and Concordance correlation, Bland-Altman plot and linear regression analyses were used to validate and compare the S-Fiber Med with other methods. Results indicate that there was no significant difference between medullation percentage obtained with the projection microscope and the S-Fiber Med. The Pearson and Concordance correlation analysis shows a strong, high and significant relationship (P-value 0.172), and they have a strong, high and significant relationship between them, given the high Pearson correlation value (r ≥ 0.96 with P-value < 0.001), high Concordance coefficient and bias correction factor. Similar results were found when PFT and OFDA100 were compared with S-Fiber Med. As a conclusion, this new system provides precise, accurate measurements of medullation and AFD in an expeditious fashion (40 seconds/sample).Open Access funding was provided by Public University of Navarre

Direct Strength Method for the Design of Purlins

The Direct Strength Method (DSM) has recently been developed by Schafer and Pekoz for the design of cold-formed steel structural members. What is now required is the calibration of the method against existing design methodologies for common structural systems such as roof and wall systems. The paper firstly explains the application of the DSM for the design of simply supported and continuous purlins. Some generalizations, such as how to handle combined bending and shear at the ends of laps, have had to be made to implement the method for continuous purlin systems. The method is then applied to study a range of section sizes in C- and Z-sections and a range of spans for simply supported, continuous and continuous lapped purlins. The results are compared with purlin design capacities to the Australian/New Zealand Standard AS/NZS 4600. This standard is similar to the AISI Specification except that it includes design rules for distortional buckling. Some modifications have had to be made to the strength equations in the DSM to achieve an accurate and reliable comparison. These modifications are included in the paper

A neglected disease of humans: a new focus of visceral leishmaniasis in Bakool, Somalia.

Visceral leishmaniasis (VL) was observed in children in Bakool region, Somalia, an area where VL has not been reported before. We describe the extent of the problem in this war- and famine-stricken area. A retrospective analysis was done of all cases admitted to a VL treatment centre between July 2000 and August 2001. Patients with longstanding fever, splenomegaly and a positive direct agglutination test (DAT; titre > 1:3200) were treated as suspected VL cases. A rapid epidemiological and entomological assessment was performed in the area. Species identification was attempted from blood samples by polymerase chain reaction-restriction fragment length polymorphism analysis of cysteine proteinase B genes. In 1 year, 230 serologically-positive cases were diagnosed as VL, and response to therapy was good in 91.6% of the 225 treated with sodium stibogluconate. Parasitological confirmation was attempted and obtained in 2 cases. Parasites were found to be most similar to Sudanese and Ethiopian reference strains of the Leishmania donovani complex. In a serological survey of 161 healthy displaced persons, 15% were positive by the leishmanin skin test and 3 (2%) were positive by the DAT. The sandfly captures showed Phlebotomus martini and P. vansomerenae. VL seems to be a longstanding and serious health problem in Bakool region. Food insecurity might have contributed to the emergence and detection of VL in this area

Empirical model for forecast the Peruvian sea surface temperature

En el presente trabajo se estudia un modelo empírico basado en el volumen de agua cálida en el Pacífi co ecuatorial que se aplica para hacer previsiones de temperatura superfi cial del mar frente a Perú, lo cual sirve como una herramienta de alerta temprana de los efectos de El Niño. La relación del volumen de agua cálida con la profundidad de la isoterma de 20 °C es mayor en el Pacífi co central en la latitud cero. Los cambios de este volumen afectan después varios meses la temperatura superfi cial del mar frente a Perú, particularmente cuando este volumen presenta anomalías positivas. El modelo logra estimar el momento en que se inicia el aumento de temperature superfi cial del mar asociado a los efectos de El Niño en la Región Niño 1 costera, el momento de ocurrencia del pico de los eventos, y las tendencias a mediano plazo. Palabras claves: Modelo empírico, volumen de agua cálida, Pacífi co Ecuatorial, temperature superfi cial, El Niño. In the present work an empirical model based on the warm water volume in the Equatorial Pacific Ocean is studied as a tool to forecast variations of sea surface temperature off the coast of Perú, which will be useful as a tool for giving early warnings of El Niño effects. The relation between the warm water volume and the depth of the 20°C isotherm is greater in the Central Pacific along latitude 0°. Several months later the changes of this volume affect the sea surface temperature off Perú particularly when its anomalies are positive. The model estimates the time when sea surface temperature begins to rise associated with El Niño effects in the coastal Niño 1 Region, the time when the event peaks, and the medium term trends. Keywords: Empirical model, warm water volume, Equatorial Pacifi c Ocean, surface temperature, El Niñ

Agricultural eco-efficiency and water footprint- A case study of fifteen crops in the Chupaca province of Peru

The water footprint is an indicator of the impact of water use from its formation to its final destination. Agricultural eco-efficiency measures the efficient use of resources or materials available for crop production. Water's economic productivity analyses a product's efficient value as per its water supply and commercial value. The present research aimed to determine and relate the water footprint, economic productivity of water and agricultural eco-efficiency of 15 crops in the province of Chupaca - Peru. Georeferencing material was used for the delimitation of agricultural species, CROPWAT 8.0, CLIMWAT8.0, ArcGis 10.5 software, mathematical equations for the water footprint, agricultural eco-efficiency (Data Envelopment Analysis (DEA)) and economic productivity of water. The Total water footprint (TWF) of the fifteen crops was 1718237.01 m3/ton, likewise the BlueWF &gt; GreenWF &gt; GreyWF. In their economic outputs, gross value of production (GVP) &gt; agricultural production (Ag-p) &gt; economic rent agricultural (ERA) was verified. In environmental costs, water consumption that meets the needs of crops (Wc-Ag) &gt; consumption of phytosanitary products (C-fly) &gt; fertilizer consumption (C-fe) was determined. The average Agricultural eco-efficiency (Ag-Eec) and Economic water productivity (Ewp) were 89.8% and 0.046 PEN/m3 respectively. Statistical analysis between Ewp and Ag-Eec was rho = 0.18, t-test = 0.66 &lt; 2.16 (α = 0.05; bilateral), and the correlation indicated that both activities are independent. The environmental costs and economic outputs of agricultural eco-efficiency did not influence the economic value of water.

Concrete cracking control in underwater marine structures using basalt fiber

The construction of coastal ports requires the use of materials that meet the demands of the marine environment, to prevent underwater concrete structures from cracking and spalling easily; basalt fiber is used to delay the expansion of concrete and prevent the formation of cracks. This research studies the behavior of concrete for prefabricated piles with Portland Cement Type I and basalt fibers added in 0.1%, 0.3% and 0.6%; the results indicate that the fiber is suitable for concrete, the slump decreases, the compressive strength increases for specimens cured in tap water and sea water, the relationship between resistances does not vary, and the depth of carbonation decreases

Analyzing solid waste landfills using satellite imagery and designing new landfill reception areas

Solid waste disposal is important for environmental management for good quality of life in urban cities. Among them is the final disposal of waste in landfills. Landfills can receive tons of waste, but they must be far away from natural resources and urban areas. The research aimed to analyze the physical and biological conditions and design a geolocation map of new sanitary landfills in three urban cities in Peru (Chilca, El Tambo and Huancayo). Landsat 8 OLI/TIRS satellite imagery was used to analyze the physical (LST and Methane) and biological (NDVI and SAVI) conditions of the landfills. The geolocation of the landfills was analyzed through the relationship, intersection and discrimination between their surface criteria (soil type, current use, geology and physiography) and climatic factors (temperature, humidity and precipitation). The physical and biological conditions of the landfills were: CH4: Chilca 8.33g &gt; Huancayo 4.76g &gt; El-Tambo 3.17g; SAVI: Chilca 0.61 &gt; El Tambo 0.54 &gt; Huancayo 0.51; LST: Huancayo 26.15°C &gt; Chilca 24.03°C &gt; El Tambo 22.75°C; NDVI: Chilca 0.85 &gt; Huancayo 0.81 &gt; El Tambo 0.8. In the three cities, "natural grasslands" were considered suitable land for the new solid waste landfill site. The multiple relationship, intersection, and discrimination of surface criteria and climatic factors were categorized into five types of sustainable geolocation (very appropriate &gt; appropriate &gt; moderately adequate &gt; less appropriate &gt; inappropriate) for new solid waste landfills. It was very important to discount the influence areas (rivers and lagoons) to avoid damaging the natural resources.