Absorption of SO2 by Pecan (Carya illinoensis (Wang) K. Koch) and Alfalfa (Medicago sativa L.) and its Effect on Net Photosynthesis

Absorption rates of SO₂ by pecan (Carya illinoensis (Wang) K.Koch) leaflets exposed to 2.6, 5.2, and 7.8 mg SO₂ m^–3were measured over a 2 h period. SO₂ was rapidly absorbed bythe leaflets in all treatments during the initial 30–50min; the rate of uptake decreased to a rather constant levelthereafter. Total SO₂ absorbed during the 2 h period was 15.6,25.6, and 38.9 nmol cm^–2 for the low, medium, and highSO₂ concentrations, respectively. Reductions in net photosyntheticrates were proportional to ambient SO₂ concentrations and totalSO₂ absorbed. Partial photosynthetic recovery occurred in alltreatments during a 2 h post-treatment period and full recoveryoccurred during a 12 h dark period. Exposure to SO₂ resultedin slight increases in stomatal and boundary layer resistancesto CO₂ and substantial increases in residual resistances. Absorptionrates of SO₂ by alfalfa (Medicago saliva L.) exposed to 5.2mg SO₂m^–3 for 1 h were approximately double those of pecanexposed to the same ambient SO₂ concentration. Alfalfa net photosyntheticrates were reduced 74% after 1 h exposure to 5.2 mg SO₂ m^–3while a depression of 42% occurred in pecan.     

In defence of model‐based inference in phylogeography

Recent papers have promoted the view that model‐based methods in general, and those based on Approximate Bayesian Computation (ABC) in particular, are flawed in a number of ways, and are therefore inappropriate for the analysis of phylogeographic data. These papers further argue that Nested Clade Phylogeographic Analysis (NCPA) offers the best approach in statistical phylogeography. In order to remove the confusion and misconceptions introduced by these papers, we justify and explain the reasoning behind model‐based inference. We argue that ABC is a statistically valid approach, alongside other computational statistical techniques that have been successfully used to infer parameters and compare models in population genetics. We also examine the NCPA method and highlight numerous deficiencies, either when used with single or multiple loci. We further show that the ages of clades are carelessly used to infer ages of demographic events, that these ages are estimated under a simple model of panmixia and population stationarity but are then used under different and unspecified models to test hypotheses, a usage the invalidates these testing procedures. We conclude by encouraging researchers to study and use model‐based inference in population genetics.     

Results of irradiation in cancer of the lip,tongue and ear

CANCER OF THE LIP: The primary lesion can be controlled by irradiation in approximately 80 per cent of cases. For lesions with metastases there is only about a 25 per cent chance of five-year arrest (irradiation of the primary lesion followed by excision of involved nodes). CANCER OF THE TONGUE: Lesions in the anterior two-thirds are controllable by irradiation in about 50 per cent of cases if the nodes are not involved; the salvage is only about 15 per cent if the nodes are involved (nodes treated surgically). Lesions in the posterior third of the tongue are seldom controlled in the author's experience. CANCER OF THE EAR (AURICLE): Five-year arrest of basal-cell lesions should be attained by irradiation in about 80 per cent of cases; of squamous-cell lesions in about 60 per cent. If the lesion is extensive, radiation does not offer a superior cosmetic result to operation and entails danger of late chondronecrosis. Therefore extensive lesions are probably best treated surgically. In either event, it appears probable that results of irradiation can be improved by the use of more adequate fields and greater fractionation.     

Radiological aspects of collagen diseases

The collagen diseases, an ill-defined group of clinical entities, have as their basis a generalized alteration of the connective tissue, especially of its extracellular components. They include periarteritis nodosa, disseminated lupus erythematosus, dermatomyositis, scleroderma, rheumatic fever and rheumatoid arthritis. The radiological findings in a series of cases of these diseases were reviewed. In 28 cases of periarteritis, 20 cases showed some abnormal findings in the thorax. These included pleural effusions, pulmonary changes, pericardial effusions and cardiac enlargement. In 32 cases of disseminated lupus erythematosus, thoracic findings were noted in 21. They resembled the changes found in periarteritis. In some 25 cases of scleroderma, diverse radiological findings were noted. These included "cystic" changes in the lungs (one case) and pulmonary "hives." In the intestinal tract esophageal and small bowel alterations were found, both ectatic and stenotic. In the soft tissues of the "pressure areas" variable degrees of calcification were observed. Dermatomyositis is the rarest of the collagen disease group; only one autopsy-proven case is available for study. Chest x-rays taken a year before death showed slight cardiac enlargement. The lungs were clear. In acute rheumatic fever, x-ray examination may disclose pericardial or pleural effusion, and so-called rheumatic pneumonitis; the latter has no specific diagnostic features. Soft tissue swellings may develop around some of the joints. In rheumatoid arthritis, joint changes are numerous and fairly characteristic, and are followed in many cases by fibrous or bony ankylosis and deformities of considerable degree. Awareness of the commoner radiological changes in this entire group of diseases should result in earlier establishment of diagnosis, especially in the more obscure examples.     

IDENTIFYING PREDATORS AT NORTHERN BOBWHITE NESTS

Abstract: We identified nest predators of northern bobwhites (Colinus virginianus) on private lands in northern Florida and southern Georgia, USA, using continuous infrared micro-video cameras, 1999–2001, and compared these results to predictions based on diagnostic sign at nests. Mammals (59%), snakes (29%), and ants (12%) accounted for known bobwhite nest depredations. Mammalian predators, in order of importance, were the raccoon (Procyon lotor), nine-banded armadillo (Dasypus novemcinctus), Virginia opossum (Didelphis virginiana), bobcat (Lynx rufus), hispid cotton rat (Sigmodon hispidus), and coyote (Canis latrans). Using diagnostic sign, technicians correctly classified 30% of mammalian depredations to species and overestimated nest depredations by snakes. A classification tree model correctly classified 75% of the test sample (n = 33) into “mammal” or “snake” categories, but still overestimated depredations by snakes. We documented a broader predator community upon bobwhite eggs than previously known for northern Florida and southern Georgia and confirmed that snakes were significant nest predators in some years. We conclude that diagnostic sign at depredated nests was unreliable for identifying nest predators of northern bobwhites.     

Estimates of Survival from Radiotelemetry: a Response to Guthery and Lusk

Abstract: Radiotelemetry has become an important and frequently used tool in wildlife research. Inferences drawn from radiotelemetry data depend on the assumption that the radiotransmitters are not influencing parameter(s) of interest. An article by Guthery and Lusk (2004) in the Wildlife Society Bulletin questioned the validity of this assumption for estimating survival rates of northern bobwhites (Colinus virginianus) using radiotelemetry data. In this evaluation, we address technical and philosophical flaws in Guthery and Lusk's (2004) critique of northern bobwhite studies utilizing radiotelemetry. They concluded that biologists should be skeptical of radiotelemetry studies and they advised researchers to design studies to address potential biases caused by radiotransmitters using independent data. Although we agree that researchers are responsible for testing key assumptions of their techniques, we believe Guthery and Lusk's (2004) conclusions were not well supported and were based on tenuous assumptions. Guthery and Lusk (2004) calculated the level of productivity (given as a fall age ratio) required to balance a simple population model that contained published estimates of annual survival and assumed an annual finite population growth rate of 1.0. We review their population model and show that the relationship between an annual survival rate and fall age ratio is nonlinear. This nonlinearity can lead to biased estimates of a fall age ratio, especially at lower values of annual survival. We also question the validity of using fall age ratios as an estimator of productivity. Further, we suggest that this assessment of a radiotransmitter effect from a survival rate itself is not appropriate. This rate can be depressed (or elevated) for a variety of reasons not related to the influence of radiotransmitters. In addition, Guthery and Lusk (2004) assumed that daily survival rates (as calculated from both annual and seasonal published estimates) were constant throughout the year; thus, they scaled daily survival rates from seasonal to annual estimates. Further, their meta-analysis was hindered by temporal pseudoreplication and a lack of independence among the observations used in the analysis. We conclude the weight of the evidence presented by Guthery and Lusk (2004) is not as strong as they claim because it fails to meet the test of sufficient causation. While scientists should always be skeptical and critical of assumptions of all methods employed in wildlife research, more rigorous tests are necessary before we discredit a valuable technique without sufficient empirical evidence.     

Atmospheric Ozone Depletion: Reduction of Photosynthesis and Growth of a Sensitive Higher Plant Exposed to Enhanced u.v.-B Radiation

Net photosynthesis and leaf growth were determined for Rumexpatientia L. exposed to four levels of u.v.-B irradiation (280–315nm). When weighted for biological effectiveness u.v.-B_BE thelowest level of this radiation employed, was less than thatcalculated for normal cloudless days in April. This resultedin detectable depressions of photosynthesis and leaf growth.Reciprocity was demonstrated in the reduction of photosynthesisby u.v.-B_BE. However, unlike photosynthesis, reduction of leafexpansion by u.v.-B_BE did not show a reciprocal mode of action.Leaf expansion was reduced as a function of the level of u.v.-B_BEand only during the initial days of exposure. A model was developed to predict reductions of net photosynthesisand leaf expansion rates under increased u.v.-B_BE correspondingto any atmospheric ozone concentration reduction. After 35 dsimulation, the calculated reductions in photosynthetic ratesfor a leaf initiated on June 1 were 6, 21, and 42 percent foru.v.-B_BE corresponding to atmospheric ozone reductions of 5,15, and 40 percent, respectively. Predicted reductions in photosyntheticcapacity and leaf expansion rates for leaves active before Junewere less severe. This is due to the lower normal u.v.-B_BE atthis time of year because of greater angles from the zenithand higher atmospheric ozone concentrations. A test of the modelshowed a good correspondence between the predicted and measuredreduction in photosynthesis of leaves exposed to supplementalu.v.-B_BE irradiation under field conditions.