Boundary conditions in the Dirac approach to graphene devices

We study a family of local boundary conditions for the Dirac problem corresponding to the continuum limit of graphene, both for nanoribbons and nanodots. We show that, among the members of such family, MIT bag boundary conditions are the ones which are in closest agreement with available experiments. For nanotubes of arbitrary chirality satisfying these last boundary conditions, we evaluate the Casimir energy via zeta function regularization, in such a way that the limit of nanoribbons is clearly determined.Comment: 10 pages, no figure. Section on Casimir energy adde

Maize breeding in East and Southern Africa, 1900–2000

"During the first half of the 20th century, African farmers transformed maize from a minor imported foodcrop into the continent's principal staple food. In the second half of the century, newly independent governments launched support programs that greatly expanded smallholder production, leading to substantial production surges of 10 to 20 years in duration. Today, after widespread adoption by both commercial farmers and smallholders, farmers now plant 58 percent of all maize area in East and Southern Africa to new high-yielding varieties, which on average outyield traditional varieties by 40–50 percent even without fertilizer....Though these maize-breeding efforts were an undeniable technical success, broader efforts to support national production growth proved fiscally unsustainable, and once heavy subsidies were withdrawn, production fell (see table). This qualified success story reveals important lessons about both the strengths and pitfalls of past agricultural development efforts in Africa." From Text.

Smoking: taxing health and Social Security

Cigarette smoking is costly in terms of not only its effects on smokers' health but also the direct and indirect financial costs it imposes on smokers and their families. For instance, premature death caused by smoking may redistribute Social Security income in unexpected ways that affect behavior and reduce the economic well-being of smokers and their dependents. ; This article examines the effects of smoking-attributable mortality on the net marginal Social Security tax rate (NMSSTR)—the difference between the statutory payroll tax rate and the present value of future benefits to which a covered worker is entitled. ; The analysis shows that smokers, as a result of shorter life expectancies, incur a higher NMSSTR than nonsmokers. This higher tax rate could have implications for both labor supply behavior and the Social Security System's funding. ; The authors note that smoking status should be considered in assessing Social Security legislative proposals designed to reduce system inequities or promote social adequacy—in particular, amendments designed to reduce poverty among young widows and widowers. Failure to take smoking status into account may unintentionally promote behavior that is detrimental to health.Social security

Smoking: taxing health and Social Security

While the health risks associated with smoking are well known, the impact on income distributions is not. This paper extends the literature by examining the distributional effects of a behavioral choice, in this case smoking, on net marginal Social Security tax rates (NMSSTR). The results show that smokers, as a result of shorter life expectancies, incur a higher NMSSTR than nonsmokers. In addition, as low-earnings workers have a higher smoking prevalence than high-earnings workers, smoking works to widen the income distribution. This higher tax rate could have implications for both labor supply behavior and Social Security system funding.

Does disability explain state-level differences in the quality of Medicare beneficiary hospital inpatient care?

Almost 20 percent of the total U.S. population and 42 percent of the population over the age of sixty-six are disabled. Research has shown that the presence of a disability can crowd out treatment for medical conditions not necessarily related to the disability and that states that are disproportionately African-American have a lower quality of hospital care. This paper uses quality of care data from the Centers for Medicare and Medicaid Services (CMS) to determine whether disability also explains state-level differences in quality of hospital care. The quality of Medicare beneficiary hospital care was measured using process measures for several medical conditions, including acute myocardial infarction, heart failure, stroke, and pneumonia, that are the leading causes of mortality. We use nonlinear least squares to assess the association between Medicare beneficiary quality of care and state- and medical system–level characteristics. The result for the key variable of interest—disability—reveals that a 1 percent increase in a state's disability rate leads to a 1 percentage point reduction in the score of the state's quality of hospital care. Without explicitly incorporating strategies to eliminate disparities in care incurred by people with disabilities, CMS may not adequately promote the goal of delivering the highest quality of care to all Medicare beneficiaries.

The quality of preventive and diagnostic medical care: why do southern states underperform?

As the cost of health care increases rapidly, the health care industry has turned its attention to methods of cost containment. However, concern exists that the drive to contain costs could lead to compromises in the quality of medical care. One practice that may slow the growth rate of health care expenditures and improve morbidity and mortality rates is the widespread use of preventive and diagnostic services. ; Using data compiled by the Centers for Medicare and Medicaid Services, this article evaluates the quality of care received by Medicare beneficiaries in each state. The authors examine states’ use of preventive services (influenza and pneumococcal immunizations) and diagnostic services (mammograms and diabetes screening tests) among Medicare beneficiaries. ; The analysis points out regional differences in preventive and diagnostic care across the United States. The West has higher levels of preventive care while the Northeast has higher scores for diagnostic care. But the South had the lowest average score for quality of care in both categories. The authors attribute differences among states’ levels of preventive and diagnostic care to their socioeconomic and demographic characteristics, noting in particular that the percentage of a state’s Medicare population that is black is inversely related to the quality of medical care. ; A better understanding of the causes behind racial disparities in the quality of medical care, the authors conclude, will promote the delivery of the highest quality of care to all Medicare beneficiaries and slow the growth rate of health care costs.

PENGARUH PROFITABILITAS, FASILITAS PERPAJAKAN, DAN KOMISARIS INDEPENDEN TERHADAP TARIF PAJAK EFEKTIF DALAM PERUSAHAAN MANUFAKTUR YANG TERDAFTAR DI BEI PERIODE 2012-2015

Penelitian ini bertujuan untuk mengetahui pengaruh indikator dari laporan tahunan pada tarif pajak efektif. Profitabilitas, fasilitas perpajakan, dan komisaris independen digunakan sebagai variabel bebas yang diduga memberikan pengaruh terhadap variabel terikat tarif pajak efektif. Periode dalam penelitian ini selama 4 tahun, yakni 2012-2015. Penelitian ini menggunakan data sekunder berupa laporan tahunan dari Bursa Efek Indonesia (BEI). Teknik yang digunakan dalam penelitian ini adalah purposive sampling dan diperoleh 50 sampel perusahaan dari total 147 populasi. Hasil penelitian ini adalah profitabilitas dan fasilitas perpajakan berpengaruh signifikan terhadap tarif pajak efektif. Sedangkan komisaris independen tidak berpengaruh terhadap tarif pajak efektif pada perusahaan Manufaktur yang terdaftar di BEI 2012-2015 This research studied the impact of annual report indicator to effective tax rate. Profitability, tax facilities, and independent commissioner were used as an independent variabel which were assumed have an impact to effective tax rate (dependent variabel). Period used are four years, from 2012 to 2015, using secondary data such as annual report published by Bursa Efek Indonesia (BEI). The technique used for sampling is purposive sampling, hence 50 company with a total population of 147. The result was profitability and tax facilities had a significant impact to effective tax rate. Independent commissioner had no significant influence to effective tax rate in Manufacturing companies in BEI 2012-2015

Maize Revolutions in Sub-Saharan Africa

There have been numerous episodes of widespread adoption of improved seed and long-term achievements in the development of the maize seed industry in Sub-Saharan Africa. This summary takes a circumspect view of technical change in maize production. Adoption of improved seed has continued to rise gradually, now representing an estimated 44 percent of maize area in Eastern and Southern Africa (outside South Africa), and 60 percent of maize area in West and Central Africa. Use of fertilizer and restorative crop management practices remains relatively low and inefficient. An array of extension models has been tested and a combination of approaches will be needed to reach maize producers in heterogeneous agricultural environments. Yield growth overall has been 1 percent over the past half-century, although this figure masks the high variability in maize yields, as well as improvements in resistance to disease and abiotic pressures that would have caused yield decline in the absence of maize breeding progress. The authors argue that conducive policies are equally, if not more, important for maize productivity in the region than the development of new technology and techniques. Currently popular, voucher-based subsidies can “crowd out” the private sector and could be fiscally unsustainable.Sub-Saharan Africa, maize, seed, Agricultural and Food Policy, Production Economics,

Stability of Extemporaneously Prepared Sodium Benzoate Oral Suspension

The stability of extemporaneously prepared sodium benzoate oral suspension in cherry syrup and Ora-Sweet was studied. Oral solutions of 250-mg/mL sodium benzoate were prepared in either cherry syrup or Ora-Sweet. To a beaker, 50 grams of Sodium Benzoate Powder USP was dissolved and filtered, the solution was divided equally into two parts, and each aliquot was added into two separate calibrated 100-mL amber vials. In the first vial, cherry syrup was added to make a final volume of 100 mL. In the second vial, Ora-Sweet was added to give a final volume of 100 mL. This process was repeated to prepare three solutions of each kind and all were stored at room temperature. A 250-µL sample was withdrawn immediately after preparation and again at 7, 14, 28, 60, and 90 days for each sample. At each time point, further dilution was made to an expected concentration of 0.25 mg/mL with sample diluent, and the samples were assayed in triplicate by stability-indicating high-performance liquid chromatography. Stability was defined as the retention of at least 90% of the initial concentration. At least 92% of the initial concentration of sodium benzoate in cherry syrup and at least 96% of the sodium benzoate in Ora-Sweet remained throughout the 90-day study period. There were no detectable changes in color and no visible microbial growth in any sample. Extemporaneously compounded suspensions of sodium benzoate in cherry syrup or Ora-Sweet were stable for at least 90 days when stored in a 4-oz amber plastic bottle at room temperature in reduced lighting

Efektivitas Billboard dan Signboard sebagai Media Promosi Suroboyo Carnival Park

Suroboyo Carnival Park merupakan theme park pertama yang ada di Surabaya. Sebagai tempat hiburan yang tergolong baru di Surabaya, Suroboyo Carnival Park gencar melakukan promosi di berbagai media, mulai dari billboard, signboard, media massa, menyebarkan voucher potongan harga, social media, mengadakan pameran hingga menyelenggarakan event. Penelitian ini dilakukan untuk mengetahui efektivitas media promosi dengan biaya terbesar yang digunakan oleh Suroboyo Carnival Park, yaitu billboard dan signboard. Dalam penelitian ini, peneliti akan mengukur efektivitas billboard dan signboard dengan menggunakan metode CRI (Customer Response Index) pada tahap awareness hingga comprehend saja. Sehingga dapat diketahui faktor-faktor komunikasi dalam billboard dan signboard manakah yang membuat responden aware dan memahami Suroboyo Carnival Park. Namun ternyata, hasil nilai dari kelima tahapan dalam CRI yaitu awareness, comprehend, interest, intention, hingga action pada billboard dan signboard telah melebihi 50%, hingga dapat disimpulkan bahwa billboard dan signboard merupakan media promosi yang efektif digunakan hingga membuat responden pada akhirnya memutuskan untuk datang (action) ke Suroboyo Carnival Park. Pada media promosi billboard, tahapan intentions merupakan tahapan dengan prosentase tertinggi, yaitu 89%. Pada media promosi signboard, prosentase terbesar terdapat pada tahap intentions pula, yaitu 95%. Jenis penelitian ini menggunakan penelitian deskriptif dengan pendekatan kuantitatif. Metode penelitian yang digunakan menggunakan survei, dan jumlah sampel yang diambil adalah 100 responden. Target penelitian ini adalah masyarakat Surabaya dengan usia 15-29 tahun dan pernah melewati Jalan Ahmad Yani Surabaya