Barriers to Urban Food Production: Perspectives of Urban Food Producers

Locally grown food systems in urban areas is globally important for numerous reasons such as food security, nutrition, financial well-being, and solutions to the many complex issues observed in areas with increasing populations. An understanding of the barriers to urban food production is needed because, if not addressed properly, they may lead to severe threats in urban communities such as food insecurity and poverty. The purpose of this qualitative study was to identify the barriers associated with urban food production. Semi-structured interviews were conducted in Columbus, Ohio, U.S.A. to collect data. Rules and regulations from city ordinances were perceived as the greatest barrier to urban food production. Negative perception towards farming, lack of marketing options, and resource scarcity were also identified as strong barriers to urban food production. Revisiting city ordinances, creating more market options for urban food producers, and directing programs, networks, organizations, and responsible people towards urban farming are recommended to eliminate barriers to urban food production. International agricultural and extension educators may consult the barriers identified in this study and use the findings as a starting point from which to support urban food production

To what distances do we know the confining potential?

We argue that asymptotically linear static potential is built in into the common procedure of extracting it from lattice Wilson loop measurements. To illustrate the point, we extract the potential by the standard lattice method in a model vacuum made of instantons. A beautiful infinitely rising linear potential is obtained in the case where the true potential is actually flattening. We argue that the flux tube formation might be also an artifact of the lattice procedure and not necessarily a measured physical effect. We conclude that at present the rising potential is known for sure up to no more than about 0.7 fm. It may explain why no screening has been clearly observed so far for adjoint sources and for fundamental sources but with dynamical fermions. Finally, we speculate on how confinement could be achieved even if the static potential in the pure glue theory is not infinitely rising.Comment: 16 pages, 5 figures. Additional arguments presented, a new figure and references adde

Carbonates, surfates, phosphates, nitrates, and organic materials: Their association in a Martian meteorite

The debate concerning the evolution of CO2 on Mars continues. It would appear that in order to explain the valley networks and other relict fluvial landforms it is necessary to accept that liquid water was once present at the surface of Mars. This in turn requires, at some point in the planet's history, a higher surface temperature than exists today, proposition explained traditionally by an early dense CO2, atmosphere. However, there are a number of problems with this notion: for instance, CO2 alone is not an efficient greenhouse gas because of its tendency to form clouds. Moreover, if there was an early dense CO2 atmosphere, it is necessary to explain where the elemental constituents now reside. There are two possibilities for the latter, namely loss to outer space of atmospheric CO2 or the formation of vast carbonate deposits. While some models of atmospheric loss predict that up to 0.4 bar of CO2 could be removed from the Martian surface, this is still not enough to account for the original atmospheric inventory, usually considered to have been in the range of 1-5 bar. Thus, most models of the evolution of the Martian surface require removal of CO2 from the atmosphere and into carbonate deposits. However, as yet, the evidence for the existence of carbonates on Mars is fairly scant. This is an issue that would have been resolved by results obtained from Mars Observer

The distribution of carbon in C1 to C6 carbonaceous chondrites

The carbon content and δ^C of carbon in ten carbonaceous chondrites, spanning petrologic grades 1 to 6,have been determined. There is a gradual change in the nature of the major carbonaceous components from C1 to C6 chondrites : C1 and C2 samples contain carbon as organics, whereas in higher petrologic types, carbon is predominantly amorphous or graphitic. This transition is consistent with carbon in C3 and C4 samples being formed either by dehydrogenation of organic materials during metamorphism on the parent body, or nebular heating followed by accretion at higher temperatures than prevailed during formation of C1-2 meteorites. In addition to a major carbonaceous component, ^C-rich interstellar grains are found in C1 and C2 samples and, to a much lesser extent, CV3 meteorites. CO3 and C4-6 meteorites do not appear to contain ^C-rich materials, a distribution controlled by primary accretion processes and not a result of secondary effects on parent-bodies. However, among the C1 to C3 meteorites aqueous activity might have acted to re-distribute ^C-rich grains by either concentrating them into C1 meteorites, or alternatively by transporting them into the source region of CV3 samples

High-Contrast NIR Polarization Imaging of MWC480

One of the key predictions of modeling from the IR excess of Herbig Ae stars is that for protoplanetary disks, where significant grain growth and settling has occurred, the dust disk has flattened to the point that it can be partially or largely shadowed by the innermost material at or near the dust sublimation radius. When the self-shadowing has already started, the outer disk is expected to be detected in scattered light only in the exceptional cases that the scale height of the dust disk at the sublimation radius is smaller than usual. High-contrast imaging combined with the IR spectral energy distribution allow us to measure the degree of flattening of the disk, as well as to determine the properties of the outer disk. We present polarimetric differential imaging in $H$ band obtained with Subaru/HiCIAO of one such system, MWC 480. The HiCIAO data were obtained at a historic minimum of the NIR excess. The disk is detected in scattered light from 0\farcs2-1\farcs0 (27.4-137AU). Together with the marginal detection of the disk from 1998 February 24 by HST/NICMOS, our data constrain the opening half angle for the disk to lie between 1.3$\leq\theta\leq 2.2^\circ$. When compared with similar measures in CO for the gas disk from the literature, the dust disk subtends only $\sim$30% of the gas disk scale height (H/R$\sim$0.03). Such a dust disk is a factor of 5-7 flatter than transitional disks, which have structural signatures that giant planets have formed.Comment: 21 pages, 6 figures, 1 table, ApJ accepted 2012-05-0

ALMA observations of the molecular gas in the debris disk of the 30 Myr old star HD 21997

The 30 Myr old A3-type star HD 21997 is one of the two known debris dust disks having a measurable amount of cold molecular gas. With the goal of understanding the physical state, origin, and evolution of the gas in young debris disks, we obtained CO line observations with the Atacama Large Millimeter/submillimeter Array (ALMA). Here we report on the detection of 12CO and 13CO in the J=2-1 and J=3-2 transitions and C18O in the J=2-1 line. The gas exhibits a Keplerian velocity curve, one of the few direct measurements of Keplerian rotation in young debris disks. The measured CO brightness distribution could be reproduced by a simple star+disk system, whose parameters are r_in < 26 AU, r_out = 138 +/- 20 AU, M_*=1.8 +0.5 -0.2 M_Sun, and i = 32.6 +/- 3.1 degrees. The total CO mass, as calculated from the optically thin C18O line, is about (4-8) x 10^-2 M_Earth, while the CO line ratios suggest a radiation temperature on the order of 6-9 K. Comparing our results with those obtained for the dust component of the HD 21997 disk from the ALMA continuum observations by Mo\'or et al., we conclude that comparable amounts of CO gas and dust are present in the disk. Interestingly, the gas and dust in the HD 21997 system are not co-located, indicating a dust-free inner gas disk within 55 AU of the star. We explore two possible scenarios for the origin of the gas. A secondary origin, which involves gas production from colliding or active planetesimals, would require unreasonably high gas production rates and would not explain why the gas and dust are not co-located. We propose that HD 21997 is a hybrid system where secondary debris dust and primordial gas coexist. HD 21997, whose age exceeds both the model predictions for disk clearing and the ages of the oldest T Tauri-like or transitional gas disks in the literature, may be a key object linking the primordial and the debris phases of disk evolution.Comment: 8 pages, 4 figures, accepted for publication in Ap

Nitrates in SNCs: Implications for the nitrogen cycle on Mars

Nitrogen is the second most abundant constituent of the Martian atmosphere, after CO2, present at a level of ca. 2.7 percent. Several authors have hypothesized that earlier in the planet's history, nitrogen was more abundant, but has been removed by processes such as exospheric loss from the atmosphere. However, an alternative sink for atmospheric nitrogen is the regolith; model calculations have predicted that, via the formation of NOx, HNO2 and HNO3 in the lower layers of the Martian atmosphere, the regolith might trap nitrite and nitrate anions, leading to the build-up of involatile nitrates. Integrated over 4.5 x 10(exp 9) yr, such a mechanism would contribute the equivalent of a layer of nitrates up to 0.3 cm thick distributed across the Martian surface. Features in thermal emission spectra of the surface of Mars have been interpreted tentatively as emanating from various anions (carbonates, bicarbonates, sulphates, etc.), and the presence of nitrates has also been addressed as a possibility. The identification of carbonates in SCN meteorites has allowed inferences to be drawn concerning the composition and evolution of the Martian atmosphere in terms of its carbon isotope systematics; if nitrites, nitrates, or other nitrogen-bearing salts could be isolated from SNC's, similar conclusions might be possible for an analogous nitrogen cycle. Nitrates are unstable, being readily soluble in water, and decomposed at temperatures between 50 C and 600 C, depending on composition. Any nitrates present in SNC's might be removed during ejection from the planet's surface, passage to Earth, or during the sample's terrestrial history, by weathering etc. The same might have been said for carbonates, but pockets of shock-produced glass (lithology C) from within the EET A79001 shergottite and bulk samples of other SNC contain this mineral, which did apparently survive. Nitrates occurring within the glassy melt pockets of lithology C in EET A79001 might likewise be protected. Lithology C glass was therefore selected for nitrate analysis, first by non-destructive infra red spectroscopy, and then by stepped combustion

Systematic Approach to Using Isentropic Stress Reverberation Techniques in Approximating Equation of State

Isentropic stress reverberations are used to obtain multiple Hugoniot states from a single plate impact experiment using a layered plate geometry, where a low impedance inner layer is embedded within a high impedance bulk structure. The mathematical framework used in this technique uses the classical Rankine-Hugoniot equations in the method of impedance matching, where the bulk material is required to have a known Hugoniot. Factors including the wave velocities in the materials, input pulse duration, inner layer thickness, and diameter of the test samples affect the number of states that can be generated from a single experiment. Experiments using 6061 aluminum and polycarbonate, respectively, as the bulk material and inner layer, accurately generated six Hugoniot states for the polycarbonate. Experiments using A572 grade 50 structural steel as the bulk material accurately generated ten Hugoniot states for the polycarbonate. For each experiment, the method can be used to generate a Hugoniot equation defining the material response of the inner layer within the domain encompassed by the specific test. The method is also confined to the low to moderate stress regions, within which Hugoniot and isentropic representations of the material are almost identical

Digital Library Jurnal dan Artikel dengan Modul Automatic Citation Format Berbasis Web

Universitas Klabat mempunyai visi untuk menjadi Universitas Riset. Untuk mewujudkannya maka setiap tahun dosen-dosen diwajibkan untuk membuat penelitian, begitupun dengan mahasiswa di Universitas Klabat. Sebuah research University yang baik ditunjang dengan fasilitas sarana perpustakaan yang baik juga. Dosen dan mahasiswa sebagai peneliti dapat memanfaatkan sarana perpustakaan dengan optimal. Masalah yang ada dalam perpustakaan di Universitas Klabat adalah akses terhadap hasil penelitian, artikel dan jurnal untuk mendapatkan informasi. Selain itu, untuk publikasi penelitian saat ini masih dalam bentuk hardcopy sehingga untuk mengakses penelitian yang ada, mahasiswa harus pergi ke kantor fakultas. Oleh karena hal tersebut, penulis merancang Digital Library Jurnal dan Artikel dengan Modul Automatic Citation Format berbasis Web yang dapat membantu penyimpanan hasil penelitian dengan dilengkapi fungsi automation citation. Software ini berbasis web agar mudah diakses oleh berbagai platform mobile. Penelitian ini menggunakan metode rekayasa perangkat lunak dengan proses model prototyping. Hasil penelitian dapat membantu researchers untuk mengakses serta mengutip jurnal atau artikel dalam membuat penelitian khususnya mahasiswa dan dosen di Universitas Klabat

Discovery of molecular gas around HD 131835 in an APEX molecular line survey of bright debris disks

Debris disks are considered to be gas-poor, but recent observations revealed molecular or atomic gas in several 10-40 Myr old systems. We used the APEX and IRAM 30m radiotelescopes to search for CO gas in 20 bright debris disks. In one case, around the 16 Myr old A-type star HD 131835, we discovered a new gas-bearing debris disk, where the CO 3-2 transition was successfully detected. No other individual system exhibited a measurable CO signal. Our Herschel Space Observatory far-infrared images of HD 131835 marginally resolved the disk both at 70 and 100$\mu$m, with a characteristic radius of ~170 au. While in stellar properties HD 131835 resembles $\beta$ Pic, its dust disk properties are similar to those of the most massive young debris disks. With the detection of gas in HD 131835 the number of known debris disks with CO content has increased to four, all of them encircling young ($\leq$40 Myr) A-type stars. Based on statistics within 125 pc, we suggest that the presence of detectable amount of gas in the most massive debris disks around young A-type stars is a common phenomenon. Our current data cannot conclude on the origin of gas in HD 131835. If the gas is secondary, arising from the disruption of planetesimals, then HD 131835 is a comparably young and in terms of its disk more massive analogue of the $\beta$ Pic system. However, it is also possible that this system similarly to HD 21997 possesses a hybrid disk, where the gas material is predominantly primordial, while the dust grains are mostly derived from planetesimals.Comment: Accepted for publication in ApJ, 18 pages, 9 figures, 5 table