The Relationship between Photosynthesis and Irradiance for Gulf of California Phytoplankton

During June 17-28, 1982, we carried on experiments to generate photosynthesis-irradiance curves for phytoplankton from five locations of the central and northern Gulf of California. Using natural sunlight, on board 14C incubations were done with samples collected from five different depths within the euphotic zone. In general there were great vertical changes of variables controlling primary productivity, even in cases where weak vertical TOC gradients indicated high instability and mixing of the euphotic zone. The assimilation number (PBm) had a two fold variation within the mixed layer. In general PBm decreased monotonically with depth due to phytoplankton conditioning to lower irradiances. Surface PBm values had a range of 8 to 15mg C. mg Chl a- 1. h-1. When a thermocline was present, PBm for the bottom of the euphotic zone was about 4 to 10% of that for surface waters. But, without a thermocline, P~ for the bottom of the euphotic zone was ~ 60% of that for surface waters, due to turbulence moving phytoplankton up and down the water column. Diatoms were abundant in three stations near Angel de la Guarda and Tiburon islands. For the station at the central gulf and the one at the very northern gulf, very few nano and microplankton were found with the inverted scope technique, but high chlorophyll concentrations and primary productivity indicated a high abundance of picoplankton. This difference in plankton size composition was not reflected in PBm values. Nutrient concentrations were high and did not limit PBm values. Our PBm values are higher than those reported for the gulf's winter phytoplankton; and they are about two times higher than those for winter phytoplankton of the oceanic region between San Diego and Acapulco. Our Gulf of California integrated primary productivity values had a range of 1.3 to 4.4gC. m-2. d-1

Impacto del turismo sobre el bienestar de los mexicanos y de los hogares que en México y sus regiones se dedican al turismo

En el debate sobre la relación entre turismo y bienestar existe consenso en que este es un poderoso instrumento para generar crecimiento eco- nómico. Trabajos en materia turística se han dedicado a cuanti car la riqueza generada por el turismo y a analizarlo como parte de una política pro-poor; sin embargo, no existen investigaciones que midan su impacto sobre el bienestar. El objetivo de esta investigación es evaluar los efectos del turismo sobre el bienestar de los mexicanos y sus regiones, así como conocer la situación de bienestar que prevalece en los hogares que en México se dedican al turismo, medido por su capacidad de consumo, la línea de bienestar urbana del Coneval y el método de Serrano.

Dichloridobis(methanol-κO)[cis-(±)-2,4,5-tris­(pyridin-2-yl)-2-imidazoline-κ3 N 2,N 3,N 4]ytterbium(III) chloride

In the crystal structure of the title complex, [YbCl2(C18H15N5)(CH3OH)2]Cl, the pseudo-penta­gonal–bipyramidal coordination geometry of the YbIII cation is composed of three N atoms from one cis-(±)-2,4,5-tris­(pyridin-2-yl)imidazoline (HL) ligand, two O atoms from two methanol mol­ecules and two Cl− anions. Chains are formed along [010] through N—H⋯Cl, O—H⋯Cl and O—H⋯N hydrogen bonds

Determinants of Mental Health and Self-Rated Health: A Model of Socioeconomic Status, Neighborhood Safety, and Physical Activity

Objectives. We investigated the underlying mechanisms of the influence of socioeconomic status (SES) on mental health and self-rated health (SRH), and evaluated how these relationships might vary by race/ethnicity, age, and gender

Phytoplankton size-fractionated chlorophyll-a off Baja California during winter, spring, and summer 2008

Spatial and temporal size-fractionated phytoplankton chlorophyll-a (Chl-a) variability as pico-nanoplankton (PN, 0.4- 8.0 µm) and nano-microplankton (NM, >8.0 µm) off Baja California is shown. Chl-a samples from the upper 200 m were obtained from nearshore, offshore, and intermediate locations during winter, spring, and summer 2008. PN-Chl-a contribution to phytoplankton biomass was ~4 times higher than NM fraction. Chl-a PN/NM ratio increased toward offshore, while total Chl-a (PN + NM) decreased. Seasonally, offshore phytoplankton cells abundance had a comparable contribution for both size-fractions, without an apparent change by the integrated water-column total Chl-a (60 mg m?2). Vertical Chl-a profiles were similar for winter and summer seasons. The highest Chl-a concentration and phytoplankton-cells abundance arose in spring, predominantly for NM at nearshore locations, reaching from 2.7-fold (nearshore: middle) to 4.2-fold (middle: offshore) ratios. Phytoplankton Chl-a increased from winter to spring (5.4 times), with maximum contribution of NM (6.6 times) at nearshore zones. Water-column integrated phytoplankton abundance was 5-fold higher in spring than winter, and 2-fold over summer. Using optical microscopy, dinoflagellate cells were the most abundant and variable phytoplankton recognizable group at intermediate zone. Smaller phytoplankton cells sustained approximately continuous biomass off Baja California. The spatial and temporal phytoplankton biomass variability was mainly influenced by an increase of larger cells as result of spring coastal upwelling events

Frequency and risk factors of intestinal parasites in pet dogs from Mexicali, Mexico

Parasitic intestinal infections in dogs represent a problem for human health, because a wide variety of these parasites have zoonotic potential. Therefore, proximity to pets puts us at risk. The objective of this study was to determine the frequency and risk factors (age, sex, size, breed, presence of ectoparasites and gastrointestinal disorders) of intestinal parasites in the feces of dogs attending a Veterinary Hospital in the City of Mexicali, Baja California, Mexico. A total of 148 fecal samples were collected from canine patients and analyzed for parasite identification and parasite load. A 12.2% (18/148) of the samples were positive to parasitic intestinal infections. The frequency of specific infections was an 8.1% of Cryptosporidium sp., followed by a 2.7% of Cystoisospora sp., and 1.4% of Toxascaris leonina. A statistical significance was identified between the presence of intestinal parasites and mongrel breed. The predominance of protozoa shows the importance of diagnosis prior to treatment with anthelminthic drugs, since preventive antiparasitic protocols are commonly used, although these particular parasites are out of the spectrum of those drugs. Cryptosporidium spp. have zoonotic potential, particularly in immunocompromised patients, and there are few or no treatment options

Carbono orgánico nuevo frente a la Península de Baja California: series de tiempo y climatología

Time series of new phytoplankton production (Pnew) off Baja California from 1970 to 2008 computed using statistical models of temperature-nitrate relationship in ten groups of coastal and oceanic stations (Lines 90, 107, 120, 137 and 157) of the CalCOFI-IMECOCAL network, are presented. Pnew was calculated from the -ratio and total primary production (Ptotal). Spatially, the most productive areas of the region were Lines 90, 120 and 157. Pnew of lines 107 and 137 had relatively low values. These two lines marked the border between the northern and southern areas of the studied region. Seasonally, Pnew was high in the spring-summer transition, decreased in summer and autumn, and increased in winter. Pnew was related to coastal upwelling index, and we conclude that for an index of less than 200 m3/s/100 m, Pnew increases and its maximum occurs in phase with the coastal upwelling index. For an upwelling index greater than200 m3/s/100 m Pnew decreases and both series are out of phase.Se presenta la serie de tiempo de la producción fitoplanctónica nueva (Pnueva) frente a la Península de Baja California de 1970 a 2008, calculada por modelos estadísticos de la relación temperatura-nitrato en diez grupos de estaciones costeras y oceánicas de las Líneas 90, 107, 120, 137 y 157 de la red CalCOFI-IMECOCAL. La Pnueva se calculó a partir de la razón- y la producción primaria total (Ptotal). Espacialmente las zonas más productivas fueron las oceánicas de las Líneas 90, 120 y 157. La Pnueva en las Líneas 107 y 137 presentó valores bajos y se comportó como un parte-aguas entre las regiones norte y sur. Estacionalmente la Pnueva fue alta en la transición primavera-verano; disminuyó en el verano y el otoño, con aumento en invierno. La Pnueva se relacionó con el índice de surgencias costeras y se concluye que para un índice de surgencias costeras menor a 200 m3/s/100 m, la Pnueva aumenta y el máximo se produce en el mismo período que las surgencias costeras. Para un índice superior a 200 m3/s/100 m la Pnueva disminuye y ambas series se desfasan temporalmente