Mesquite Research Articles

Colorblind Segregation: Equal Protection as a Bar to Neighborhood Integration

For ten years in the 1960s and 70s, not one dollar was spent on maintenance or modernization of a sprawling public housing project of 3,500 units known as West Dallas. The Dallas Housing Authority had lost all federal revenue for refusing to comply with federal fair housing laws - public housing in the city was segregated by race, and nearly every occupant in West Dallas was black. By the end of that period, West Dallas residents were five times more likely to be murdered than elsewhere in the city.Intervening in this human tragedy and political controversy in 1989, a federal district judge ordered local officials to take affirmative steps to remedy their pattern of housing segregation. Among those steps, the court ordered construction of small-scale housing in white, low-poverty neighborhoods. In 1999, in Walker v. City of Mesquite, Texas (“Walker V”), a case challenging the constitutionality of the district court’s race-conscious remedial order, the Fifth Circuit upheld the Fourteenth Amendment reverse discrimination claim of white homeowners near a Dallas site proposed for a forty-unit public housing development. Walker V was not alone in bringing reverse discrimination claims into the realm of residential desegregation - a challenge to race-conscious court orders had also arisen in the Yonkers litigation battle in the Second Circuit. Notwithstanding the fact that a majority of the Supreme Court refused to follow the Fifth Circuit’s equal protection jurisprudence in Grutter v. Bollinger, and in spite of a 1976 Court decision upholding race-conscious remedies to housing segregation in Chicago, Walker V cast a long shadow in equal protection jurisprudence. The decision charted a new direction in colorblindness doctrine: restraint of courts’ remedial power to redress constitutional violations involving race. That doctrinal development interacts with current housing policies to prevent meaningful ways for public housing authorities to use race-neutral means to overcome their past role in enforcing racial segregation. Together, this confluence of doctrine and policy might be called colorblind segregation jurisprudence: a framework in which court ordered remedies for unconstitutional segregation and housing discrimination must be race-neutral, thereby preserving existing patterns of neighborhood advantage polarized by race. This Comment uses Walker V as a case study to explore the meaning and potential consequences of a colorblind segregation regime. Underlying this inquiry into colorblind segregation jurisprudence lurks a question at the heart of the Second Reconstruction: When a state actor is found liable for implementing an explicit program of unconstitutional racial segregation, how far must a court go towards dismantling the entrenched edifice of urban scale racial divisions? How far can they go?

Determination of the Thermal Diffusivity of Edible Films

One of the most important factors in the preparation of edible films regards the choice of ingredients. Edible films are commonly prepared with single or mixed high-molecular-weight compounds like proteins and gums. In the present work, protein and gum-based edible films were prepared and their thermal diffusivity determined by photoacoustics. The films were prepared with different concentrations of four basic ingredients: whey protein concentrate, mesquite gum, sodium alginate, and κ-carrageenan. In single-component films, the highest thermal diffusivity was found in mesquite gum (1.97×10−7m2ċs−1), followed by sodium alginate, whey protein concentrate, and κ-carrageenan samples. In composed films, the highest thermal diffusivity was obtained in a ternary film made of mesquite gum, whey protein concentrate, and sodium alginate in identical parts (5.20×10−7m2ċs−1).

Is that lone positive skin test to mesquite for real?

Rationale A positive skin test is supposed to represent specific IgE antibody to an allergen extract. We often see positive skin tests to mesquite pollen, sometimes as the only positive, despite the fact that mesquite trees are rare in San Diego. We sought to determine if these are true positives. Methods Skin test panels were reviewed. Subjects who had mesquite as the only positive, or at least the only positive pollen, and who were not on immunotherapy, were asked to consent to a confirmatory CAP-RAST test. As a control group, those with isolated positive skin tests to olive tree pollen (common in our area) were similarly investigated. Skin test and in vitro test results were compared. Results 963 consecutive skin test panels were reviewed. Overall, 304 (32%) were positive for mesquite and 264 (27%) were positive for olive. 20 (2.1%) had mesquite as the only positive skin test. 14 (1.5%) had mesquite as the only positive pollen, but had some other, non-pollen aeroallergen positive. The corresponding numbers for olive tree pollen were 3 (0.3%) and 1 (0.1%); p<0.001 for both compared to mesquite. 16 patients with mesquite as the only positive skin test or pollen had CAP-RAST to mesquite; all were negative. 2 patients with olive as the only positive skin test had CAP-RAST to olive; both were positive. Conclusions When mesquite tree pollen results in an isolated positive skin test, it likely represents a false positive result. In some patients this allergen extract apparently has the ability to cause direct mast cell degranulation.

The human allergens of mesquite (Prosopis juliflora)

BackgroundA computerized statistical analysis of allergy skin test results correlating patient reactivities initiated our interest in the cross-reactive allergens of mesquite tree pollen. In-vitro testing with mesquite-sensitized rabbits and a variety of deciduous tree pollens revealed so many cross-reactivities that it became apparent there could be more allergens in mesquite than previously described in the world literature. Our purpose was to examine the allergens of mesquite tree pollen (Prosopis juliflora) which elicit an IgE response in allergic humans so that future research could determine if these human allergens cross-react with various tree pollens in the same manner as did the mesquite antiserum from sensitized rabbits.MethodsProteins from commercial mesquite tree pollen were separated by polyacrylamide gel electrophoresis in the presence of sodium-dodecyl-sulphate. These mesquite proteins were subjected to Western blotting using pooled sera from ten mesquite-sensitive patients and goat anti-human IgE. The allergens were detected using an Amplified Opti-4-CN kit, scanned, and then interpreted by Gel-Pro software.ResultsThirteen human allergens of mesquite pollen were detected in this study.ConclusionThe number of allergens in this study of mesquite exceeded the number identified previously in the literature. With the increased exposure to mesquite through its use in "greening the desert", increased travel to desert areas and exposure to mesquite in cooking smoke, the possible clinical significance of these allergens and their suggested cross-reactivity with other tree pollens merit further study.

Effect of caking and stickiness on the retention of spray‐dried encapsulated orange peel oil

AbstractFlavour microcapsules containing amorphous carbohydrate as wall material can undergo changes such as crystallisation, clumping, sticking and caking during handling and storage. Such physical changes may lead to the release of entrapped flavours. The objective of this study was to investigate the effect of storage temperature and water activity on caking, stickiness and glass transition temperatures and to evaluate the relative degree of protection provided to orange peel oil entrapped in mesquite (Prosopis juliflora) gum by spray drying. The powders were stored at water activities (aw) ranging from 0.108 to 0.972 at 25 and 35 °C. The surface caking temperature (Tsc) and advance caking temperature (Tac) were determined by the modified ampoule and sealed glass tube methods respectively. The glass transition temperature was determined by differential scanning calorimetry. Changes in the amount of encapsulated oil were determined by Clevenger hydrodistillation. As expected, both Tsc and Tac decreased with increasing storage aw. Above aw 0.628 the powders caked and collapsed during storage at 35 °C. Below aw 0.628 the capsules were not damaged and high retention levels (above 90%) were obtained. Increasing aw in the range 0.743–0.972 caused progressive dissolution of the wall polymer, and the retention level dropped sharply. The volatiles are protected and retained by mesquite gum as long as the capsule structure remains intact. Copyright © 2003 Society of Chemical Industry

Interannual and seasonal variation in fluxes of water and carbon dioxide from a riparian woodland ecosystem

Fluxes of water, energy and carbon dioxide (CO 2) were measured using the eddy covariance technique over a mesquite ( Prosopis velutina) woodland along the San Pedro River in southeastern Arizona for the entire growing seasons of 2001 and 2002, between the last freeze event of spring and the first of fall. Although the general pattern of ecosystem response to climate forcing was similar in both years, latent heat and CO 2 fluxes showed significant variations between and within the growing seasons. The main differences between the two years were a consequence of an extended drought that lasted from October 2001 to July 2002. Most of the within season variability was attributable to the timing and magnitude of mid-summer precipitation associated with the North American Monsoon. Following new tree leaf production and prior to the monsoon onset, there was little precipitation; daytime air temperatures were high and relative humidity low. Evapotranspiration and water level data indicated that the mesquite trees always had ready access to groundwater, though they were likely supplementing this with vadose zone soil water when abundant. Nonetheless, decreases in afternoon transpiration and CO 2 uptake suggest stomatal regulation of leaf gas exchange, possibly in response to the high vapor pressure deficit. Because near-surface soil moisture was limited prior to the summer rains, ecosystem respiration was low and there was little evapotranspiration from understory plants and soil. With the arrival of the monsoon rains, understory vegetation activity and, consequently, total ecosystem evapotranspiration increased. Total ecosystem photosynthesis also increased, but the net uptake of carbon decreased, due to enhanced respiration from the abundant carbon sources, stimulated by the precipitation and warm temperatures. The nighttime measurements of CO 2 fluxes, although of questionable accuracy, imply the ecosystem was a net sink of CO 2 for most of the two growing seasons.

Mesquite gum: fractionation and characterization of the gum exuded from Prosopis laevigata obtained from plant tissue culture and from wild trees

The effect of abiotic and biotic stresses in the in vitro gum production from Prosopis laevigata has been studied. The presence of autoclaved microbial biomass (MB) in combination with an incubation temperature of 35 °C induced the greatest gum production. In vitro and in situ gum samples from mesquite were fractionated by hydrophobic affinity chromatography. The results indicated that both gums consist of five principal fractions. The protein content of the fractions varied greatly (0.04–50.05%). For both gums, the protein content in the fractions (F) increased in the following order F2a<F1<F2b<F3a<F3b. The monosaccharide compositions, protein contents and other analyses of whole gums also were performed. The molecular mass distribution was determined by gel permeation chromatography (GPC). Showing the existence of five components varying in molecular mass from 3.5×10 4 to 9.4×10 5.

Effective moisture diffusivity in biopolymer drops by regular regime theory

The effective moisture diffusivity coefficient ( D eff) of maltodextrin DE 10 (MD-10), gum arabic (GA), mesquite gum (MG) and ovalbumin (OA) drop solutions was calculated using regular regime theory. Isothermal drying of the biopolymer drops was done at 50, 60, 70 and 80 °C with a thermogravimetric analyzer, and changes in drop shape upon drying were followed with image analysis system. MD-10, GA and MG exhibited drop shrinkage upon drying described by second order polynomial, but OA did not. D eff was dependent on moisture content and temperature. Activation energy ( E a) of the biopolymers was calculated from the slope of average effective diffusivity ( D eff ) against temperature plots. E a values exhibited by biopolymers drops from highest to lowest were: MD-10 (29.043 kJ/mol), MG (23.939 kJ/mol), GA (19.213 kJ/mol) and OA (7.487 kJ/mol).

Estimation of the activation energy of carbohydrate polymers blends as selection criteria for their use as wall material for spray-dried microcapsules

A quantitative method for selecting the most suitable biopolymers blends for lipid materials microencapsulation is proposed. Aqueous solutions of carbohydrate polymers blends (gum arabic (GA), mesquite gum (MG) and maltodextrin DE 10 (MD)) were prepared in accordance to a Simplex Centroid experimental design, and a drop of each blend was dried isothermally at 50, 60 and 80 °C in a thermogravimetric analyzer. The effective diffusivity was dependent on moisture content, drop volume shrinkage, and temperature. Drop shrinkage was estimated from polynomial models reported for GA, MG and MD, assuming additive volumes of the blend constituents. Activation energies were calculated considering that the average effective diffusivity followed an Arrhenius-type relationship. The pure biopolymer exhibiting the highest activation energy was MD, followed by MG and GA, respectively. Blends containing 66%GA-17%MG-17%MD and 17%GA-66%MG-17%MD showed higher activation energies than MD, MG and GA suggesting that they better suited for protecting microencapsulated lipids against oxidation.

Moisture barrier properties and morphology of mesquite gum–candelilla wax based edible emulsion coatings

Composite edible coatings were formulated with candelilla wax alone, and candelilla wax blended with beeswax, white mineral oil and oleic acid (2:1 ratios) as the lipid phase, and mesquite gum as the structural material and their corrected water vapor permeability (WVPc) were determined. The coatings were applied to Persian limes and their effect upon physiological weight loss, color and chemical composition changes were evaluated. Addition of the blend of candelilla wax–mineral oil improved the WVPc ( P<0.05) of the candelilla wax–mesquite gum coating formulation, and provided the lowest physiological weight loss, best dark shade green colour retention and unaltered physicochemical parameters to Persian limes, in comparison to the rest of the coating formulations tested. There was a close relationship between the performance and the microstructure of coatings. Coatings showing more uniform and less defects (fissures, fractures, pinholes) in the surface morphology were those exhibiting the lowest WVP values.

Dynamics of carbon, nitrogen and phosphorus in soil amended with irradiated, pasteurized and limed biosolids.

Sewage biosolids contain high concentrations of pathogens, which limits their use as soil amendment. This study investigated how application of lime (Ca(OH)2), irradiation, or pasteurization reduced pathogens in biosolids and how its application affected soil characteristics. A soil sampled outside the canopy of Mesquite trees (Prosopis laevigata) and from a pasture at Lerma (Mexico) was amended with treated or untreated biosolids, characterized and incubated aerobically while dynamics of carbon (C), nitrogen (N) and phosphorus (P) were monitored. Heavy metals concentrations in the biosolids were low, so it was of excellent quality (USEPA). The amount of pathogens in the biosolids made it a class "B" (USEPA) which can be used in forests. Only irradiation sufficiently reduced faecal coliforms to make it a class "A" biosolids without restrictions in application. C mineralization increased significantly when biosolids were added, but not concentrations of available P (P < 0.05). Ammonium (NH4+) concentrations in soil amended with biosolids were higher compared to unamended soil, but not the concentrations of nitrate (NO3-) except when biosolids treated with Ca(OH)2 was added to the Lerma soil.

A View from the Outside

I remember sitting in a classroom in West Texas several years ago, listening to my English professor lecture on some British author. Actually, he was staring out the window and telling us about the remarkable attributes of mesquite trees — there was some connection between Lord Byron and southwestern vegetation. At that moment, like the heavenly light dazzling Saul on the road to Damascus, a voice inside me said, “That’s what I want to be, an English professor!” What a great job! You have nice colleagues, wear tweed sport coats with bow ties, give lectures on Byron and mesquite trees, and get paid for it! I could do this, I told myself (with only the vaguest sense of what “graduate school” was going to be like). Had the Fates been kind, they would have given me a copy of a book like Mentor in a Manual to read before mailing out those graduate school applications. Mentor in a Manual is something like a U.S. Army training manual as compared to the travel agency brochures one might find at a recruiting office (“See Hawaii!— Join the Marines!”). It is encyclopedic, loaded with useful hints and suggestions for survival, and it will disabuse anyone of romantic ideas about academe, just as reading about bayonets puts Hawaii in a different light. Not that I regret choosing a career in academe. The professorial calling does have its unique pleasures, but I might have considered my career alternatives as a librarian or navy midshipman more seriously had I known that being good is not always good enough in academe. As Schoenfeld and Magnan put it in their preface, “There is no entitlement to tenure based upon a record that is merely competent and satisfactory for a prescribed period of time” (xiii).

Effect of Water Activity on the Stability to Oxidation of Spray‐Dried Encapsulated Orange Peel Oil Using Mesquite Gum (Prosopis Juliflora) as Wall Material

ABSTRACT: Mesquite gum solutions (30% w/v) were used to emulsify orange peel oil in an oil‐gum solids ratio of 0.25. Emulsions were spray dried in laboratory scale equipment. The powders were stored in aw(s) from 0.108 to 0.743 at 35 °C. Quantitative analysis of limonene oxide indicated that the sample at 0.628 showed a very good stability against oxidation after thirty d, without caking and stickiness occurring. At this water activity the system was within rubbery state, and the moisture content corresponded to that of the minimum integral entropy.

Thermodynamic analysis of the sorption process of mesquite gum

Determination of the thermodynamic parameters, allows for a more thorough interpretation of sorption isotherms and provides a better insight into sorption mechanisms. In this work, the adsorption and desorption isotherms of mesquite gum were determined at 25, 35 and 45 degrees C. All isotherms were fitted using the GAB model and the thermodynamic properties were estimated by Othmer's method. The hysteresis decreased when temperature increased. However the effect of temperature was higher on the desorption isotherms, indicating the existence of metastable states. The adsorption process showed smaller enthalpy values during the hysteresis as compared to desorption process. The minimum integral entropy for the adsorption and desorption was located around 14 gH2O/100 g dry solids. This suggests that it is possible to determine the most suitable conditions for storage, using adsorption or desorption isotherms.

Cross-reactivity of mesquite tree pollen with deciduous tree pollens

Cross-reactivity of mesquite tree pollen with deciduous tree pollens

Mesquite and Grass Interference with Establishing Redberry Juniper Seedlings

Excessive cover of juniper (Juniperus pinchotii Sudw.) reduces forage production, interferes with livestock management, and diminishes the watershed and wildlife habitat values of rangelands. We studied whether juniper seedlings were differentially suppressed in the presence of different grass species, and to what extent established mesquite (Prosopis glandulosa Torr.) trees facilitated or competed with establishing juniper seedlings. Seedlings growing with any of the grasses (RGR = 0.23 to 0.43 cm cm(-1)) grew significantly less than those with no grass competition (RGR = 0.72 cm cm(-1))(P 0.05), indicating that mesquite root competition with juniper is probably inconsequential. Since junipers grow mainly in fall, winter and spring when mesquite trees are dormant and leafless, the lack of competition may largely be due to these 2 species using resources at different times of the year. Greater nutrient availability beneath mesquite canopies, reduction of summer temperatures, and temporal separation of resource use clearly benefit juniper seedlings growing in the presence of mesquite. Managing for a vigorous grass component with low densities and cover of mesquite is the best way to limit the rate of invasion by juniper. DOI:10.2458/azu_jrm_v54i6_teague

Development of Microcapsules Containing Water and Lipid Soluble Natural Colorants for Trout Pigmentation

Microcapsules containing water and lipid dispersible natural colorants were formed using as wall materials mesquite gum and gum arabic. The theoretical total pigment concentration of the microcapsules was 4.6 g/kg. Spectrophotometric measurements indicated that the microencapsulated pigments underwent zero order degradation kinetics, and that mesquite gum provided the pigments a better protection than gum arabic. Mesquite gum microcapsules complied with the requisite of exhibiting a pigment degradation of less than 10% during 6 months, while the gum arabic microcapsules did not. Likewise the chromatic parameters a, b and L experienced zero order kinetics decrease, which was more pronounced for the gum arabic microcapsules. The superior protection provided by mesquite gum is attributed to the thicker adsorbed polymer layers of the microcapsules due to its higher molecular mass as compared to that of gum arabic. Trouts fed diets containing the microcapsules for three weeks acquired muscle pigmentation similar to the color exhibited by the natural colorant blend in the microcapsule, establishing the feasibility of employing these microcapsules in fish pigmentation.

Nutritive Value and Aversion of Honey Mesquite Leaves to Sheep

Honey mesquite (Prosopis glandulosa Torr.) is an invasive native plant that is abundant in Mexico and the Southwestern United States. We initiated 2 studies to determine if: 1) mesquite could provide valuable forage for domestic herbivores; and 2) if mesquite causes conditioned flavor aversions in ruminants. An in vivo digestion trial was completed with 15 lambs assigned to diets of 0, 5, 10, 15, or 20% dried mesquite leaves mixed with alfalfa hay to measure effects of mesquite on intake and digestion. Proportions of mesquite leaves > 5% of the diet negatively affected dry matter (DM) intake, nitrogen (N) balance, energy balance and weight gain. Mesquite intake was highest at the 5% level averaging 1.81 g kg-1 body weight (BW), mesquite intake of the other mesquite-containing diets averaged 0.78 g kg-1 BW. Apparent digestibility was not affected by the level of mesquite in the diet. An in situ digestion trial did however, reveal that pure alfalfa was more digestible than mesquite leaves. A conditioned flavor aversion (CFA) trial tested the effect of post-ingestive feedback from mesquite on the intake of a novel food (rye). Lambs were offered rye and then ground mesquite was infused into their rumens by esophageal tube. Twenty one lambs were assigned to 3 dosing treatments: 0 (control), 3.0 (low), or 4.5 (high) g of mesquite per kg BW. Two days after dosing, lambs that received mesquite infusions ate less rye than controls indicating the formation of a CFA. The aversion to rye persisted for at least 2 days. The high dose of mesquite also decreased intake of the alfalfa basal ration for at least 3 days and resulted in persistent diarrhea in lambs. Chemical analysis of mesquite leaves revealed similar nutritive quality (crude protein, gross energy, and fiber) as mature alfalfa. However, to exploit the forage value of mesquite, the allelochemicals that cause flavor aversions and other negative digestive consequences need to be identified and overcome. DOI:10.2458/azu_jrm_v54i1_baptista

Effect of foaming agents on the stability, rheological properties, drying kinetics and flavour retention of tamarind foam-mats

Tamarind foam-mats were prepared using as foaming agents ovalbumin, mesquite gum and a low molecular weight surface active blend, by themselves or in combination, in accordance to a 2 3 factorial experimental design. The stability, rheological properties (flow and viscoelasticity) and drying kinetics of the different foam treatments were evaluated. Sensory evaluation of the dried powders was performed. Response surface analysis yielded polynomial models that explain the influence of the foaming agents treatments on the selected foams response variables: drainage mean time, yield stress, apparent plastic viscosity, critical drying time, instantaneous elastic modulus, and mean retardation time. In general terms, the use of binary combinations of the foaming agents at their high usage level yielded foams that exhibited longer drainage mean times; higher yield stress, apparent plastic viscosity, instantaneous elastic modulus and mean retardation times; and a shorter onset of the critical drying time, that yielded dried tamarind powders with better sensory flavour perception. A close interrelationship existed between the drainage mean time and the apparent plastic viscosity, and between the critical drying time and the mean retardation time of the foams.

Mesquite and grass interference with establishing redberry juniper seedlings

Excessive cover of juniper (Juniperus pinchotii Sudw.) reduces forage production, interferes with livestock management, and diminishes the watershed and wildlife habitat values of rangelands. We studied whether juniper seedlings were differentially suppressed in the presence of different grass species, and to what extent established mesquite (Prosopis glandulosa Torr.) trees facilitated or competed with establishing juniper seedlings. Seedlings growing with any of the grasses (RGR = 0.23 to 0.43 cm cm(-1)) grew significantly less than those with no grass competition (RGR = 0.72 cm cm(-1))(P &lt; 0.01). Juniper seedlings grew significantly less in the presence of buffalograss (Buchloe dactyloides (Nutt.) Engelm.) (RGR = 0.23 cm cm(-1) than with either sideoats grama (Bouteloua curtipendula (Michx.) Torr.) (RGR = 0.43 cm cm(-1)) or tobosagrass (Hilaria mutica [Buckl.] Benth.) (RGR = 0.43 cm cm(-1))(P &lt; 0.01). In contrast, juniper seedlings grew larger under intact canopies of mesquite (RGR = 0.99 cm cm(-1)) than in open grassland (RGR = 0.65 cm cm(-1))(P &lt; 0.05) due in part to the greater nutrient availability (P &lt; 0.05) under mesquite canopies. Juniper growing in sub-canopy positions with mesquite trees removed grew less (RGR = 0.84 cm cm(-1)) than those growing under mesquite canopies with root competition (RGR = 0.99 cm cm(-1))(P &lt; 0.05). Juniper growing under intact mesquite canopies but without mesquite root competition, grew no better or worse (RGR = 0.93 cm cm(-1)) than those with mesquite root competition (RGR = 0.99 cm cm(-1))(P &gt; 0.05), indicating that mesquite root competition with juniper is probably inconsequential. Since junipers grow mainly in fall, winter and spring when mesquite trees are dormant and leafless, the lack of competition may largely be due to these 2 species using resources at different times of the year. Greater nutrient availability beneath mesquite canopies, reduction of summer temperatures, and temporal separation of resource use clearly benefit juniper seedlings growing in the presence of mesquite. Managing for a vigorous grass component with low densities and cover of mesquite is the best way to limit the rate of invasion by juniper.