Perils of a Modern Collector

Provides the history of starting the Greater Boston Philatelic Society.&nbsp

Letter from George Gantzer

Letter concerning a position at Utah Agricultural College

Characterization of runoff and infiltration from no-till soybeans with selected winter cover crops

The influence of "living mulch" winter cover crops on soil loss, runoff amount and quality and soybean growth was studied at the Midwest Claypan Experimental runoff plots located on Mexico silt loam (Udollic Ochraqualf). Experimental treatments consisted of no-till soybeans with: 1) canada bluegrass (Poa compressa L.), 2) chickweed (Stellaria media h), 3) downy brome (Bromus tectorum L.), and 4) no cover crop (CK). Runoff, sediment, dissolved nutrients, soil water content, and plant growth characteristics were measured. For chickweed (CW), canada bluegrass (CB) and downy brome (DB) treatments, runoff was reduced 66, 56, and 80 percent (P [less than] 0.01), and soil loss was decreased 61, 97, and 95 percent (P [less than] 0.01), respectively, vs. the CK treatment. Concentrations of dissolved NH4+-N and P04-3-P in runoff water from cover crop plots were 2 to 2.8 times higher than the CK (P [less than] 0.05). Runoff from the CK had a higher concentration of dissolved No3--N. Total amounts of dissolved N03--N losses were significantly decreased by 71, 73, and 76 percent (P [less than] 0.01) and NH4+-N losses reduced by 40, 36, and 46 percent (P [less than] 0.10) for treatments of CW, CB, and DB vs. the CK, respectively. P04-3-P losses also were decreased by 50, 21, and 39 percent for CW, CB, and DB vs. CK, but differences were not significant (P [greater than] 0.10). Lower plant populations and delayed plant development decreased soybean yield in cover crop treatments from 18 to 62 percent (P [less than] 0.01) vs. the CK.Project # G-1235-03 Agreement # 14-08-0001-G-1235-0

Security Bug Report Classification using Feature Selection, Clustering, and Deep Learning

As the numbers of software vulnerabilities and cybersecurity threats increase, it is becoming more difficult and time consuming to classify bug reports manually. This thesis is focused on exploring techniques that have potential to improve the performance of automated classification of software bug reports as security or non-security related. Using supervised learning, feature selection was used to engineer new feature vectors to be used in machine learning. Feature selection changes the vocabulary used by selecting words with the greatest impact on classification. Feature selection was able to increase the F-Score across the datasets by increasing the precision. We also explored unsupervised classification based on clustering. A distribution of software issues was created using variational autoencoders, where the majority of security related issues were closely related. However, a portion of non-security issues also ended up in the distribution. Furthermore, we explored recent advances in text mining classification based on deep learning. Specifically, we used recurrent networks for supervised and semi-supervised classification. LSTM networks outperformed the Naive Bayes classifier in projects with a high ratio of security related issues. Sequence autoencoders were trained on unlabeled data and tuned with labeled data. The results showed that using unlabeled software issues different from the testing datasets degraded the results. Sequence autoencoders may be used on large datasets, where labeled data is scarce

Timing of Nordic Hamstring Exercise in Youth Soccer Players to Reduce Injury

The Nordic hamstring exercise (NHE) has been demonstrated to be an effective strength exercise to help mitigate the risk of hamstring injury in soccer players. It is a component of the FIFA 11+ grassroots injury prevention program, which is a series of warm-up exercises designed to be administered in large groups and at minimal cost. Recent evidence in adults suggests that the acute fatigue associated with the NHE may increase the risk of injury during training, causing some to suggest moving the NHE until the end of training. PURPOSE: To determine whether this same level of fatigue persists in young soccer players, where training intensities and volumes are often much lower than in adults. METHODS: We designed a field-based crossover experimental study where youth soccer players completed two experimental sessions in a randomized manner. Participants included 18 youth players (mean ± SD: males, n=18; age 15.5 ± 0.7 years, height 1.77 ± 0.13 m, weight 66.4 ± 10.8 kg) participating in the Major League Soccer (MLS) Next player development pathway in Phoenix, USA. One session included the NHE as part of a standardized warm-up prior to a 75-minute standardized training session, and the alternative session incorporated the NHE at the end of the training session. Maximal hamstring force was measured at baseline, post-warm-up, and after completion of training. RESULTS: There was no interaction, condition, or main effect of NHE timing as indicated by maximal force output in the left (p \u3e 0.69) and right leg (p \u3e 0.65). CONCLUSION: Our findings add to the growing body of literature with regard to lower-limb fatigue profiles and adolescent soccer players, as well as suggest youth soccer coaches should not be concerned with the timing of these interventions, allowing them to focus instead on adherence and player buy-in

About the Authors

About the authors.&nbsp

Role of streambed biofilms in the removal of biodegradable contaminants from shallow streams

Biological activity in shallow streams is dominated by biofilms which are attached to the surface of the streambed. Although biofilm kinetic models are well developed and are successfully applied to biological treatment process, they cannot be applied directly to predict water quality in shallow streams, because the area and mass-transport aspects of streambed biofilms are complicated and not defined. Therefore, the main purpose of this study was to develop area and mass-transport functions for cobble-and gravel-lined streambeds. An artificial stream was used to grow biofilms and conduct kinetic experiments on the biofilm utilization of an easily degraded sugar. Media size (i.e., cobble or gravel) and flow velocity were varied over a wide range of values typical to shallow streams. Water velocity had short-term and long-term effects on the rate of contaminant removal. The short-term effects were related to increased mass-transport kinetics for higher flow velocities, while the long-term effects also included increased surface colonization by biofilm. The cobble streambed was more sensitive to short-term changes in water velocity than was the gravel bed, and it gave faster removal kinetics. Equations to predict the mass transfer coefficients were appropriate for more than one biofilm community, as long as the same medium size was used. The simulations from the water quality models containing the biofilm reaction term were markedly different from the simulations from traditional water-quality models that use only suspended organism kinetics.U.S. Department of the InteriorU.S. Geological SurveyOpe

Role of runoff and interflow in chemical transport for claypan soils

Students supported: 2 Student AssistantsNo-tillage systems have been found to increase water runoff for some soils. This is a major concern because this increased runoff has the potential for increasing the runoff of dissolved herbicides in the spring since these chemicals are not incorporated into the soil with no-tillage systems. This study was conducted to evaluate the effects of seven longterm crop and tillage systems on runoff and saturated hydraulic conductivity. The study was conducted near Kingdom City, Missouri on a Mexico silt loam (fine, montmorillonitic, mesic Udollic Ochraqualf). Runoff records from 1983 through 1993 were collected. The seven treatments consisted of no-tillage (NT), moldboard plow (MP), and chisel plow (CP) continuous corn (Zea mays L.) and continuous soybean (Glycine max L.) and fallow (F). Saturated hydraulic conductivity (Ksat), bulk density, organic matter, and water content were determined on soil cores removed from two interrow positions (trafficked and non-trafficked) and two soil depths (0 - 125 mm, 125 - 150 mm). Tillage had a small but significant effect on runoff, Ksat, bulk density, water content at sampling, and organic matter. The Fallow treatment produced the lowest values of Ksat (0.2 mm/h), bulk density (1.3 g cm^-3), and organic matter content (0.9 percent) for the surface 125 mm, as compared to the NT, MB and CP treatments. No differences in Ksat were found (p=0.587) among NT, MP and CP tillage treatments. Complex interaction effects of tillage vs. wheel traffic (p=0.039) and tillage vs. depth (p=0.003) suggested that tillage effects on Ksat vary with interrow position and soil depth. The NT (0.301 mm mm^-3) had significantly higher field volumetric water content than MP (0.285 mm mm^-3) and CP (0.282 mm mm^-3), when averaged across crops. Plots planted to corn had greater water content (0.297 mm mm^-3) compared to soybean plots (0.281 mm mm^-3). Runoff under F was the highest in each year from 1983 to 1993. The greatest amount of runoff occurred during Period 4 (harvest to planting). Runoff was lowest during Period 1 and 2. No-tillage had significantly higher runoff than MP and CP treatments during Period 4, spring (p=0.006); Period 4, fall (p=0.011 ); Fallow period (p=0.005); and Period 1 and 2 (p=0.021). Cumulative runoff with NT was significantly (p=0.001) higher compared to MP and CP, except from 1991 to 1993 in which differences were not significant (p=0.374). Corn produced lower runoff rates than soybean at the 0.05 level in Period 4, fall. Increased runoff in NT was attributed to higher water content and subsequently lower infiltration for this soil which had a nearly impermeable subsurface argillic horizon.Project # G-2029-02 Agreement # 14-08-0001-G-2029-0

Chlordane movement during rainfall

Indoor rainfall simulation experiments were conducted to quantify the mass of technical chlordane leaving an experimental soil box in runoff, splash and leachate. The initial mass of technical chlordane was uniformly distributed throughout the soil at concentrations equal to those recommended for termite control around basement and foundation walls. Two silt loam soils and one sandy soil were studied. The mass of chlordane in runoff adsorbed to organic matter was estimated to be 16 times the mass of chlordane in runoff adsorbed to clay. For a soil with a clay-to-organic-matter ratio as high as 66, the mass of chlordane in runoff appears to be predominantly a function of clay content. For a soil with a clay-to-organic-matter ratio as low as 2 to 5, the mass of chlordane in runoff appears to be predominantly a function of organic matter content. An increase in rainfall intensity from 51 to 102 mm/hr increased chlordane mass in runoff by 300 to 500 percent. This increase in rainfall intensity increased the chlordane-to-sediment mass ratio in the runoff by 7 to 18 percent. The chlordane mass in runoff was 5 to 9 times as great as the mass of bromide in runoff. The chlordane mass in splash was 25 percent of the chlordane mass in runoff. Only the sandy soil at the higher rainfall intensity produced leachate. The chlordane mass in this leachate during the rainfall period was 37 percent of the chlordane mass in runoff and 264 percent of the chlordane mass in splash. The total chlordane mass which left the soil box by runoff, splash and leachate was equivalent to 4 to 44 mg per square foot of treated surface. This amounted to 0.03 to 0.31 percent of the original chlordane mass applied to the experimental soil box. This could potentially occur from previous legal surface applications in agriculture and turf management, from more recent illegal surface applications in agriculture and turf management, from proper use (according to label directions) as a subsurface termiticide but where depth of untreated cover soil was insufficient, from improper use as a subsurface termiticide where treated soil remained uncovered at the surface or from disturbance by new construction of large areas treated in previous years. This type of horizontal movement of chlordane and other organochlorine pesticides has been documented. Bennett et al. (1974) measured 70 ppb of gamma chlordane in the top five inches of soil located 10 feet away from a foundation wall treated 21 years earlier. Lichtenstein (1958) found higher concentrations of the organochlorine insecticides aldrin, lindane and DDT on the downslope side than on the upslope side of treated test plots. Similarly, Peach et al. (1973) found surface movement of aldrin, lindane and heptachlor toward points of lower elevation in a sloping field. Haan (1971) conducted laboratory rainfall-runoff experiments following surface treatment with aldrin, dieldrin and DDT and found that sediment carried more than twice as much pesticide mass as the water. Wauchope (1978) reviewed the literature on pesticide losses in runoff water from agricultural fields. He found that organochlorine pesticides lose about 1 percent of the total mass applied to the field through runoff. This compared to other commercial pesticides which lose 0.5 percent or less unless severe rainfall conditions occur within 2 weeks after application. Another important consideration is the mass of pesticide located within a few millimeters of the soil surface. Investigators have found that it is this zone from which pesticides are released during rainfall. Sharpley (1985) studied 5 soils and found the depth of this zone to range from 2 to 4 mm for 4 percent slopes under 50 mm/hr rainfall intensity to 13 to 37 mm for 20 percent slopes under 160 mm/hr rainfall intensity.Project # G-1432-04 Agreement # 14-08-0001-G-1423-0

Macropore effects on pesticides transport to groundwater

The objective of this investigation was to evaluate the leaching and degradation characteristics of atrazine and bromide in a field of alluvial soils under irrigated, no-till management. The experimental site was 0.1 ha in size. The soils were Sarpy (mixed, mesic Typic Udipsamments) with the surface texture varying from silt loam to loamy sand. Atrazine was applied at 2.2 kg/ha after sorghum (Sorghum bicolor) was planted. Bromide was applied at 115 kg/ha five days later. Soil cores were extracted to a depth of 150 cm which were segmented into 7.5 cm increments and were analyzed for each of the chemicals separately. The dates for sampling were one week, one month, two months, three months, and four months after application of the chemicals. As a result 1134 and 3542 soil samples were extracted for atrazine and bromide analysis, respectively. Atrazine was detected within the 15 to 22.5 cm depth increment one week after application. These data suggest that some of the atrazine can move to depth of 20 cm after one week which is probably due to the presence of macropores (1-5 mm diameter holes) open to the soil surface which were present in this field under no-till management. Atrazine was detected at very low concentrations at two and four months after application. Although extreme variability in atrazine concentrations occurred, the variations were not explained totally by differences in soil texture. The data in this study indicate some potential, although small, for atrazine contamination of groundwater.Project # G-1432-03 Agreement # 14-08-0001-G-1423-0