¿Cómo se comportan las tasas de desempleo en siete ciudades colombianas?

A pesar de su importancia y al igual que otras variables, la tasa de desempleo usualmente ha sido analizada desde una perspectiva nacional, desconociendo caracter�sticas de cada ciudad o regi�n. No obstante las claras diferencias regionales en el entorno colombiano, muy pocos trabajos han abordado el problema partiendo de esas diferencias. En este trabajo se utilizan las tasas de desempleo de siete ciudades para analizar similitudes y diferencias. A partir de la construcci�n de un �ndice de dispersi�n de las series se aprecia un movimiento proc�clico de las diferencias, es decir, aumentos en las diferencias al disminuir el desempleo. Del mismo modo, al aumentar el desempleo las diferencias tienden a disminuir. Adicionalmente, mediante el an�lisis de cointegraci�n de Johansen se logra identificar relaciones de largo plazo entre las series consideradas, al igual que mecanismos de ajuste de las diferencias en el corto plazo. A partir de este an�lisis se encuentra evidencia de una explicaci�n de equilibrio de largo plazo, al igual que efectos de desequilibrios en el corto plazo.desempleo, cointegración, índice de dispersión, economía regional

¿Se comportan igual las tasas de desempleo de las siete principales ciudades colombianas?

Partiendo de las tasas de desempleo de las siete principales ciudades colombianas se calcula un índice de dispersión, además se utiliza la prueba de cointegración de Johansen para examinar las diferencias y relaciones de largo plazo de estas series. A partir del cálculo de los índices de dispersión se encontró un movimiento procíclico del movimiento de las tasas y su dispersión. Cuando las ciudades están en la etapa favorable del ciclo, con bajas tasas de desempleo, las desigualdades aumentan. Por otro lado, cuando las tasas de desempleo están en niveles relativamente bajos, las desigualdades, medidas por los índices de dispersión, disminuyen. Por último, se evalúo la cointegración de las series. Se realizaron seis modelos, una evaluando la cointegración de cinco ciudades con el comportamiento promedio y un último modelo examinando la cointegración del grupo de cinco ciudades. En general, se encontró que cada una de las cinco series estaban cointegradas con el comportamiento del grupo. Además, se encontró la presencia de tres vectores de cointegración al considerar el conjunto de las cinco ciudades.Desempleo,

Characterization of the Small RNA Transcriptome of the Marine Coccolithophorid, Emiliania huxleyi

Small RNAs (smRNAs) control a variety of cellular processes by silencing target genes at the transcriptional or post-transcription level. While extensively studied in plants, relatively little is known about smRNAs and their targets in marine phytoplankton, such as Emiliania huxleyi (E. huxleyi). Deep sequencing was performed of smRNAs extracted at different time points as E. huxleyi cells transition from logarithmic to stationary phase growth in batch culture. Computational analyses predicted 18 E. huxleyi specific miRNAs. The 18 miRNA candidates and their precursors vary in length (18-24 nt and 71-252 nt, respectively), genome copy number (3-1,459), and the number of genes targeted (2-107). Stem-loop real time reverse transcriptase (RT) PCR was used to validate miRNA expression which varied by nearly three orders of magnitude when growth slows and cells enter stationary phase. Stem-loop RT PCR was also used to examine the expression profiles of miRNA in calcifying and non-calcifying cultures, and a small subset was found to be differentially expressed when nutrients become limiting and calcification is enhanced. In addition to miRNAs, endogenous small RNAs such as ra-siRNAs, ta-siRNAs, nat-siRNAs, and piwiRNAs were predicted along with the machinery for the biogenesis and processing of si-RNAs. This study is the first genome-wide investigation smRNAs pathways in E. huxleyi. Results provide new insights into the importance of smRNAs in regulating aspects of physiological growth and adaptation in marine phytoplankton and further challenge the notion that smRNAs evolved with multicellularity, expanding our perspective of these ancient regulatory pathways

Genotoxicity of nitroso compounds and sodium dichromate in a model combining organ cultures of human nasal epithelia and the comet assay

Genotoxic effects of xenobiotics are a possible step in tumor initiation in the mucosa of the upper aerodigestive tract. Using the comet assay, detecting genotoxicity in human tissue has been restricted to single incubations in vitro, but in vivo most xenobiotics harm their target in a repetitive or chronic manner. Therefore, we propose a model, which provides repetitive incubations in human upper aerodigestive tract mucosa cultures. Samples of human inferior nasal turbinate mucosa (n = 25) were cultured according to a modified version of a technique originally described by Steinsvag. On day 1 fresh samples and on days 7, 9 and 11 organ cultures were incubated with N-nitrosodiethylamine (NDEA), sodium dichromate (Na2Cr2O7) and N'-methyl-N-nitro-N-nitrosoguanidine(MNNG). Mucosa samples and organ cultures, respectively, underwent a modified comet assay on days 1, 7 and 11. Genotoxicity could be shown for NDEA, Na2Cr2O7 and MNNG on days 1, 7 and 11. Duration of tissue culture and repetitive incubations did not significantly influence the results for NDEA. Nevertheless, Na2Cr2O7 and MNNG caused higher genotoxic effects on cultures subjected to the comet assay on day 11. This model may help to assess genotoxic hazards posed by environ mental pollutants that have a cumulative character in repetitive or chronic exposure in vivo. Copyright (C) 2001 S. Karger AG, Basel

SITUACIÓN ACTUAL Y PERSPECTIVAS DE LA GANADERÍA LECHERA EN LA CUENCA DE LIMA

El sector lechero, progresivamente, está integrando la economía global; caracterizada por las exportaciones-importaciones privadas de productos, menos intervención de los gobiernos y las inversiones foráneas en la industria láctea. Este cambiante ambiente crea amenazas y también oportunidades. Para mejor entendimiento del impacto de la liberalización global del comercio sobre la competitividad de la lechería peruana en estos mercados, no podemos ignorar las consecuencias del GATT y los Acuerdos de la Ronda del Uruguay que están cambiando toda la situación.El sector lechero, progresivamente, está integrando la economía global; caracterizada por las exportaciones-importaciones privadas de productos, menos intervención de los gobiernos y las inversiones foráneas en la industria láctea. Este cambiante ambiente crea amenazas y también oportunidades. Para mejor entendimiento del impacto de la liberalización global del comercio sobre la competitividad de la lechería peruana en estos mercados, no podemos ignorar las consecuencias del GATT y los Acuerdos de la Ronda del Uruguay que están cambiando toda la situación

LATHROBIUM (LATHROBIUM) NEGREI JARRIGE, 1952, NUEVA ESPECIE PARA LA FAUNA DE LA PENÍNSULA IBÉRICA (COLEOPTERA, STAPHYLINIDAE, PAEDERINAE)

The species Lathrobium (Lathrobium) negrei is recorded for the first time in the Iberian peninsula, Mar de Ontigola, Aranjuez, province of Madrid. Diagnostic characteristics, its aedeagus and the groove from near margin of sternite pygidial are furnished. New data on the geographical distribution are provided. It is an element “betico-rifeño” considered as riparium of salty soils.Lathrobium (Lathrobium) negrei Jarrige, 1952 es recogida por primera vez en la Península Ibérica en el “Mar de Ontigola”, Aranjuez, provincia de Madrid. Se detallan y se representan las caracteristicas morfológicas del edeago y de la escotadura del esternito pigidial del macho. Se amplia el conocimiento sobre la distribución geográfica de la especie, considerándola como elemento betico-rifeño. Se señalan sus preferencias ecológicas, como ripícola de aguas salobres

Are My Dry Cows Heat-Stressed? A Novel Approach to Assess Heat Stress of Dry Cows in Commercial Dairy Herds

Heat stress during the dry period causes major economic losses to the dairy industry. However, limited research exists regarding responses of dry cows exposed to various temperature and relative humidity gradients. In addition, no validated methods are currently available to assess heat stress in dry cows. The goals of this study were to describe core body temperature (CBT) responses of dry cows according to a variety of temperature-humidity index (THI) values, and develop and validate a practical method to assess heat stress in dry cows in commercial dairy herds. This study was comprised of 2 parts. In the first part of the study, vaginal temperature of dry cows (n = 346) with 250 to 260 days of gestation from 5 herds was assessed for 4 to 7 consecutive days in 5-minute intervals. Within dairy and parity group, cows were classified as having high (HT) or low CBT (LT). By design, CBT was greater for HT compared with LT cows (102.3 ± 0.01 vs. 101.8 ± 0.01°F). Cows classified as having HT had shorter gestation length compared with their LT counterparts (272.5 ± 0.2 vs. 275.1 ± 0.2 days). The second part of the study consisted of evaluating and validating a practical assessment method of heat stress and investigating CBT threshold values. Vaginal temperature of 1,540 dry cows with 236 to 250 days of gestation from 3 commercial dairy herds was assessed a single time using a digital thermometer. Average CBT of HT cows at each THI (data from the first part of the study) was used as a threshold value to classify cows as heat-susceptible or heat-tolerant. Cows with higher or lower CBT than the threshold defined for a given THI were classified as heat-susceptible or tolerant, respectively. Cows classified as heat-susceptible had shorter gestation length (272.5 ± 0.2 vs. 275.0 ± 0.2 days) and were more likely to have twins (11.0 vs. 3.8%) than heat-tolerant cows. In conclusion, assessment of heat stress in dry cows based on defined CBT thresholds is a useful method to identify cows expected to have shorter gestation length and more likely to have twins

Effects of Two Commercial Supplemental Fat Products on Body Condition Score and Cow- and Herd-Level Milk Yield and Composition in a Commercial Dairy Herd in Kansas

Feeding fat supplements to lactating dairy cows is an effective strategy to increase energy density of rations and increase milk yield. However, it is not clear whether supplementing a specific fat supplement for the entire lactating herd provides better results than others in commercial dairy herds. The objective of this study was to compare the effects of fat supplementation with two commercial products on changes in body condition score (BCS) and cow- and herd-level milk production and composition in a large commercial dairy herd. The study was conducted in a herd milking approximately 1,500 Holstein cows. One of two treatments was assigned to the herd in a singlesubject crossover design with 4 periods. Treatments were inclusion of 0.24 lb/cow per day of a supplement rich in saturated fats (Propel; Propel Energy Plus) or 0.22 lb/cow per day of a supplement containing calcium salts of long-chain fatty acids (Control). Treatments were applied to all lactating cows during four consecutive weeks. Milk yield recorded during the last week of each period was used for statistical analyses. In addition, milk samples were collected in the last week of each period to determine test-day milk protein, fat, somatic cell count, and urea nitrogen concentrations. At the beginning and at the end of each experimental period, BCS was assessed from a subset of cows to evaluate BCS change. Herd-level milk fat, protein, and somatic cell count were recorded daily by the milk cooperative. Bulk tank milk fat and protein contents on the fourth week of fat supplementation were similar between Control and Propel treatments. Average milk yield during the fourth week of fat supplementation (yield recorded daily in the last week of the experimental period) was greater for Control than Propel supplementation (83.4 vs. 82.1 ± 1.7 lb/day). In the analyses that used test-day data, milk yield did not differ between Control and Propel treatments. Supplementation with Propel resulted in greater milk fat (4.50 vs. 4.29 ± 0.12%) and reduced milk protein content (3.12 vs. 3.14 ± 0.03%) compared with Control. In addition, milk urea nitrogen was reduced for Control vs. Propel cows (12.5 vs. 13.1 ± 0.04 mg/dL). Supplementation with Propel increased energy-corrected milk (93.9 vs. 91.7 ± 3.1 lb/ day) and fat-corrected milk (96.3 vs. 93.5 ± 3.3 lb/day) yields compared with Control supplementation. Proportion of cows that lost BCS during the fat supplementation periods did not differ between treatments; however, BCS change tended to be more pronounced during supplementation with Propel than Control treatment (-0.03 vs. 0.02 ± 0.04). In conclusion, fat supplementation using the Propel treatment resulted in greater milk fat content, energy-corrected milk, and fat-corrected milk compared with fat supplementation with Control. Our findings suggest that the type of market to which milk is sold should be considered in the choice of fat supplements