Proxying economic activity with daytime satellite imagery: Filling data gaps across time and space.

This paper develops a novel procedure for proxying economic activity with daytime satellite imagery across time periods and spatial units, for which reliable data on economic activity are otherwise not available. In developing this unique proxy, we apply machine-learning techniques to a historical time series of daytime satellite imagery dating back to 1984. Compared to satellite data on night light intensity, another common economic proxy, our proxy more precisely predicts economic activity at smaller regional levels and over longer time horizons. We demonstrate our measure's usefulness for the example of Germany, where East German data on economic activity are unavailable for detailed regional levels and historical time series. Our procedure is generalizable to any region in the world, and it has great potential for analyzing historical economic developments, evaluating local policy reforms, and controlling for economic activity at highly disaggregated regional levels in econometric applications.

Increased expression of hypoxia-inducible factor-1 alpha and its impact on transcriptional changes and prognosis in malignant tumours of the ocular adnexa.

PURPOSE: To investigate the expression profile of the hypoxia-inducible transcription factor-1α (HIF-1α) and its downstream targets in malignancies of the ocular adnexa and to determine its relevance as a prognostic factor for clinical outcome. METHODS: We included 49 subjects with malignant tumours (25 squamous cell carcinomas (SCC), 15 non-Hodgkin lymphomas, 9 melanomas) and 30 patients with benign tumours of the ocular adnexa (13 papillomas, 7 reactive lymphoid hyperplasias (RLHs) and 10 nevi) as controls. We quantified HIF-1α protein expression by immunohistochemistry and assessed the association between HIF-1α and clinical outcome via Kaplan-Meier analysis. Furthermore, we assessed the expression of HIF-1α downstream factors by transcriptional sequencing using the MACE (massive analysis of cDNA ends) technology. RESULTS: SCCs revealed a strong HIF-1α expression in 61% of tumour cells in comparison with only 22% in papillomas (p < 0.0001). In contrast, malignant melanomas and lymphomas revealed a similar HIF-1α expression compared with nevi and RLHs. Transcriptional sequencing and Gene Ontology Cluster analysis demonstrated 37 hypoxia-associated factors, including HIF-1α, VEGF, SFRP1 and LOXL2 that are significantly increased in SCC and may contribute to tumour proliferation, angiogenesis, and metastasis. Association analysis between HIF-1α immunoreactivity and clinical outcome revealed a trend towards an unfavourable prognosis in malignant tumours with increased HIF-1α expression. CONCLUSIONS: HIF-1α protein is increased in malignant tumours of the ocular adnexa, which is associated with an increase in multiple HIF-1α-downstream factors and a trend towards an unfavourable clinical outcome.