MRI-only based radiotherapy treatment planning for the rat brain on a Small Animal Radiation Research Platform (SARRP)

Computed tomography (CT) is the standard imaging modality in radiation therapy treatment planning (RTP). However, magnetic resonance (MR) imaging provides superior soft tissue contrast, increasing the precision of target volume selection. We present MR-only based RTP for a rat brain on a small animal radiation research platform (SARRP) using probabilistic voxel classification with multiple MR sequences. Six rat heads were imaged, each with one CT and five MR sequences. The MR sequences were: T1-weighted, T2-weighted, zero-echo time (ZTE), and two ultra-short echo time sequences with 20 mu s (UTE1) and 2 ms (UTE2) echo times. CT data were manually segmented into air, soft tissue, and bone to obtain the RTP reference. Bias field corrected MR images were automatically segmented into the same tissue classes using a fuzzy c-means segmentation algorithm with multiple images as input. Similarities between segmented CT and automatic segmented MR (ASMR) images were evaluated using Dice coefficient. Three ASMR images with high similarity index were used for further RTP. Three beam arrangements were investigated. Dose distributions were compared by analysing dose volume histograms. The highest Dice coefficients were obtained for the ZTE-UTE2 combination and for the T1-UTE1-T2 combination when ZTE was unavailable. Both combinations, along with UTE1-UTE2, often used to generate ASMR images, were used for further RTP. Using 1 beam, MR based RTP underestimated the dose to be delivered to the target (range: 1.4%-7.6%). When more complex beam configurations were used, the calculated dose using the ZTE-UTE2 combination was the most accurate, with 0.7% deviation from CT, compared to 0.8% for T1-UTE1-T2 and 1.7% for UTE1-UTE2. The presented MR-only based workflow for RTP on a SARRP enables both accurate organ delineation and dose calculations using multiple MR sequences. This method can be useful in longitudinal studies where CT's cumulative radiation dose might contribute to the total dose

Proximity to Industrial Releases of Toxins and Childhood Respiratory, Developmental, and Neurological Diseases: Environmental Ascription in East Baton Rouge Parish

Recent research by Legot et al. (2010a, 2010b) has identified East Baton Rouge Parish (EBR) as a locus of particularly high volumes of emissions of developmental neurotoxins, i.e., those toxins that put children’s health and, especially, learning abilities at greatest risk. Many developmental neurotoxins are also classified as respiratory toxins, which are also linked to the sorts of childhood diseases (e.g., asthma) that impact school performance. This case study specifies the degree to which proximity to the main sources of these toxins in EBR is associated with high rates of neurodevelopmental diseases and childhood asthma. We also examine the relationship between proximity to toxins and race and class.<span>  </span>We find very strong patterns: disease rates are significantly higher in zip codes close to pollution “hot spots” than in more distant zip codes, as are percent minority and percent poverty.<span>  </span>This is evidence of “environmental ascription”, the existence of multiple, overlapping ascriptions based on race, class, and “place”.<span>  </span>Vulnerable populations are disproportionately exposed to the sorts of toxins that limit their life chances.<p></p>environmental ascription; developmental neurotoxins; respiratory toxins; childhood diseases; vulnerable populations

The Proximity of High Volume Developmental Neurotoxin Polluters to Schools: Vulnerable Populations at Risk

A substantial amount of environmental justice research has taken the form of “proximity studies” that analyze the race and class composition of populations living in close proximity to general sources of pollution. Such studies often find disproportionate minority, poverty, and low-income populations proximate to the pollution source. This proximity study has a different starting point. We begin by locating nearly 700 of the nation’s highest volume polluters of specific toxins that put children’s health and learning abilities at risk: developmental neurotoxins. We then examine (a) the numbers of schools and children located within two miles of each polluter, and (b) the race and class compositions of the populations within two miles. The result is a study of the proximity of vulnerable populations to pollution that highlights the vulnerability of children, not just that of minorities and the poor. We find thousands of schools and hundreds of thousands of children at risk. We also find that a substantial proportion of the high volume polluters studied are surrounded by disproportionate minority, poverty, and low-income populations.proximity studies; environmental inequality; developmental toxins; neurotoxins; high-volume polluters; vulnerable populations: race and class, schools and children

PERAN PERILAKU KEWIRAUSAHAAN TERHADAP KINERJA PERUSAHAAN UMKM

Meneliti tentang perilaku kewirausahaan maka akan mempelajari tentang sikap, perilaku, tingkah laku, karakteristik seorang wirausahawan dalam hal ini pemilik atau pengelola usaha dalam mengelola usahanya. Perilaku dari seorang wirausahawan tentu tidak dapat dianggap remeh dan dianggap sebelah mata karena dari perilaku kewirausahaan tersebutlah kinerja dari suatu usaha akan terbentuk. Cerminan seorang yang memiliki perilaku kewirausahaan dalam hal ini yang digunakan untuk mengelola usaha dengan skala UMKM harus memiliki sikap proaktif, berorientasi pada prestasi, dan komitmen pada pihak lain agar usaha mampu bersaing dengan kompetitor sejenisnya. Jenis penelitian ini merupakan penelitian telaah pustaka atau literature review yang berisikan penelitian terdahulu terkait dengan peran perilaku kewirausahaan terhadap kinerja perusahaan. &nbsp;Kata Kunci: Perilaku Kewirausahaan, Kinerja Perusahaan